JP2004198414A - Fractography method for crystalline polymer material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely judge a breaking mode when having an extremely similar fracture pattern, even when different in the breaking mode. <P>SOLUTION: In this fractography method for a molding of a crystalline polymer material having a spherulite texture, for example, a polyacetal, an aromatic polyester, a polyarylene sulfide, a polyolefin, a polyamide and a mixture thereof, a fracture and a form of a spherulite in a just under side of the fracture from a fracture side are observed by a scanning electron microscope, and a form of the spherulite in the vicinity of the spherulite in a fracture cross-section is observed in addition thereto, when necessary. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention provides a method for analyzing a fracture surface (referred to as a fracture surface) of a crystalline polymer material having a spherulite structure by observing a fracture surface subjected to soft etching by a scanning electron microscope (abbreviated as SEM). The present invention relates to a fracture surface analysis method for investigating a spherulite morphology immediately below a fracture surface by also using a polarizing microscope and / or SEM observation of a plane cross section. According to the present invention, it is possible to determine a failure mode that could not be determined by a conventional method.

Fracture analysis is a widely used method for estimating the failure mechanism or the cause of failure from the features of the fracture pattern mainly in the field of metal. Similar to metal materials, various fracture surfaces are exhibited by fracture mechanisms in the same manner as metal materials. Therefore, similar fracture surface analysis methods have recently been adopted in the field of polymer materials. (See, for example, Non-Patent Documents 1 and 2.) In addition, other resin manufacturers or analytical institutions have issued technical data on fracture surface analysis.
Among these, in the conventional fracture surface analysis, only the observation method using the naked eye, an optical microscope, or an electron microscope while using the fracture surface as it is was used. Therefore, there has been no application of morphological observation of a spherulite immediately below a fracture surface or observation of a fracture surface cross section to fracture analysis. In addition, in observing the crystal structure of the surface of the crystalline polymer material, etching is applied in order to remove an amorphous portion in the sample with an acid or the like to leave a crystalline portion. A technique is described in which a metal is vapor-deposited from above, carbon is vapor-deposited from directly above, and a replica thin film is prepared based on the metal thin-film, and the transmission thin film is observed with a transmission electron microscope. Not a technology. (For example, see Patent Document 1)

JP-A-4-12242 (Claim 1 and Examples) Sugano Otoya, Ikeda Yoshimasa, "Molding", 1992, Vol. 4, No. 2, p. 74-92 Sugano Otoya, "Synthetic Resin", 1997, Vol. 43, No. 7, p. 39−42

In the conventional fracture surface analysis, the fracture surface is observed as it is, and the fracture pattern is determined by confirming the fracture surface pattern. The fracture surface shows a different fracture pattern depending on the fracture mode. However, even if the fracture mode differs depending on the material and grade, the fracture surface pattern is very similar, and it is difficult to determine the fracture pattern. In many cases, the fracture mode cannot be determined.
In view of the above, according to the present invention, it is possible to distinguish a fractured surface in which it is difficult to determine a fractured surface pattern by a conventional method of directly observing a fractured surface and to determine a fracture mode, or to confirm a discrimination result. The purpose is to provide a new fracture surface analysis method for the purpose.

The present inventors have previously observed cross sections in which spherulites are deformed or fractured surfaces in which spherulites are exposed. In view of the above, it was considered that the morphology of the spherulite immediately below the fracture surface could be observed by treating the fracture surface by some method.
For example, polyacetal or aromatic polyester is a crystalline polymer material, and has a spherulite structure when crystallized through a normal molding process.
The present inventors have found that polyacetal is a material that is degraded by ultraviolet rays, so that the fracture surface of polyacetal can be etched using a sample that has been softly etched using short-wavelength ultraviolet rays, or an aromatic polyester can be used as a base. Since it is a material that degrades with a basic solution, the fracture surface of the aromatic polyester is observed by SEM using a basic solution, preferably using a sample that has been softly etched with a basic solution after being irradiated with ultraviolet rays. By doing so, it has been found that the morphology of spherulites immediately below the fracture surface can be revealed and embodied from the fracture surface side while maintaining the characteristic fracture surface patterns exhibited by the various fracture surfaces.
In addition, in addition to the above, the spherulite morphology in the vicinity of the fracture surface of the fracture surface cross section is observed by a polarizing microscope, and it is found that the above problem can be solved by observing a sample subjected to soft etching by SEM, The present invention has been completed.

Immediately, a first aspect of the present invention is a method for analyzing a fracture surface of a crystalline polymer material having a spherulite structure, in which a fracture surface is observed (O) by a scanning electron microscope and a sphere immediately below the fracture surface from the fracture surface side. The present invention provides a fracture surface analysis method characterized by performing a morphological observation (A) of a crystal.
A second aspect of the present invention is the fracture surface analysis method according to the first aspect of the present invention, which further employs a morphology observation (B) of a spherulite near a fracture surface (depth from the fracture surface to 100 μm) of the fracture surface cross section. I will provide a.
A third aspect of the present invention is the fracture surface analysis according to the first or second aspect of the present invention, wherein the crystalline polymer having a spherulite structure is polyacetal, aromatic polyester, polyarylene sulfide, polyolefin, polyamide, or a mixture thereof. Provide a method.
A fourth aspect of the present invention is (i) a ductile fracture surface, (ii) a fatigue fracture surface, (iii) a brittle fracture surface, (iv) a creep fracture surface, or a composite fracture surface of the present invention used for discrimination. A fracture surface analysis method according to any one of the first to third aspects is provided.
A fifth aspect of the present invention is that the morphological observation (A) uses a soft etching method (S) in which a spherulite morphology just below the fracture surface appears while maintaining a characteristic fracture surface pattern of various fracture modes. The present invention provides the fracture surface analysis method according to any one of the first to fourth aspects of the present invention, which is a morphological observation (1) of a spherulite immediately below the fracture surface from the surface side.
A sixth aspect of the present invention is that the morphological observation (B) uses a polarizing microscope to observe the morphology of a spherulite near the fracture surface of the fracture surface cross section (2) and / or uses the soft etching method (S) described above. The method for analyzing a fracture surface according to any one of the first to fifth aspects of the present invention, which is a morphological observation (3) of a spherulite in the vicinity of the fracture surface of the fracture surface cross section by a scanning electron microscope.
A seventh aspect of the present invention is that the soft etching method (S) irradiates the fractured surface of the polyacetal with ultraviolet rays and etches the fractured surface without impairing the characteristic shape of the fractured surface. The present invention provides the fracture surface analysis method according to the fifth or sixth aspect of the present invention, which is an etching method (S1) that makes the form appear.
An eighth aspect of the present invention provides the fracture surface analysis method according to the seventh aspect, wherein the wavelength of the ultraviolet light is 300 nm or less.
A ninth aspect of the present invention is that the etching method (S1) uses a scanning electron microscope to observe a fractured surface of a polyacetal that has been subjected to primary vapor deposition of a metal to a thickness of 3 to 12 μm, and then irradiates ultraviolet rays. The present invention provides the fracture surface analysis method according to the seventh or eighth aspect of the present invention, which is a method of etching the primary vapor-deposited fracture surface to reveal a spherulite form immediately below the fracture surface.
A tenth aspect of the present invention provides the fracture surface analysis method according to the ninth aspect of the present invention, wherein the etching depth of the polyacetal portion is 1 to 20 µm.
An eleventh aspect of the present invention provides the fracture surface analysis method according to any one of the seventh to tenth aspects of the present invention, wherein irradiation conditions of the fracture surface with ultraviolet light are 8 to 10 mW / cm ² for 40 to 70 minutes.
A twelfth aspect of the present invention is that the soft etching method (S) etches the fractured surface of the aromatic polyester using a basic solution without damaging the characteristic shape of the fractured surface, and directly under the fractured surface. The present invention provides the fracture surface analysis method according to the fifth or sixth aspect of the present invention, which is an etching method (S4) for producing a spherulite morphology.
A thirteenth aspect of the present invention provides the fracture surface analysis method according to the twelfth aspect, wherein the basic solution is an alcoholic solution of sodium hydroxide.
A fourteenth aspect of the present invention is the twelfth or twelfth aspect of the present invention, wherein the basic solution is an alcohol solution having a concentration of 1 to 10% by weight, and the treatment temperature is 5 to 40 ° C. and the treatment time is 0.5 to 5 hours. 13. A fracture surface analysis method according to item 13.
According to a fifteenth aspect of the present invention, there is provided the fracture surface analysis method according to any one of the twelfth to fourteenth aspects of the present invention, wherein the fracture surface of the aromatic polyester is irradiated with ultraviolet light in advance and then treated with a basic solution.
In a sixteenth aspect of the present invention, there is provided the fracture surface analysis method according to any one of the twelfth to fifteenth aspects of the present invention, wherein the condition for irradiating the fracture surface of the molded article with ultraviolet light is 8 to 10 mW / cm ² for 30 to 90 minutes. provide.
A seventeenth aspect of the present invention is that a fractured surface of a crystalline polyester resin molded product is subjected to primary vapor deposition of a metal, and the fractured surface is observed with a scanning electron microscope. Either of the twelfth to sixteenth aspects of the present invention, in which the primary vapor-deposited fracture surface is etched to reveal a spherulite morphology immediately below the fracture surface, and a metal is further vapor-deposited to form a sample for a scanning electron microscope. The present invention provides a fracture surface analysis method as described above.
The eighteenth aspect of the present invention is the fracture surface analysis method according to any one of the twelfth to seventeenth aspects of the present invention, wherein the thickness of the primary metal is 3 to 12 nm and the thickness of the secondary metal is 12 to 16 nm. I will provide a.
A nineteenth aspect of the present invention provides the fracture surface analysis method according to any one of the twelfth to eighteenth aspects of the present invention, wherein the etching depth of the aromatic polyester is 1 to 5 μm.
A twentieth aspect of the present invention provides the fracture surface analysis method according to any one of the twelfth to nineteenth aspects of the present invention, wherein the aromatic polyester is polybutylene terephthalate.

  According to the present invention, while maintaining the characteristic pattern of the fracture surface of the crystalline resin molded article, the morphology of spherulites immediately below the fracture surface can be made to appear, and therefore, the characteristic characteristic indicated by each fracture mode It is possible to clarify the mechanism of expression of the fracture surface pattern and to judge the fracture mode more accurately.

  Examples of the crystalline polymer having a spherulite structure used in the present invention include polyacetal; aromatic dicarboxylic acid-aliphatic diol polyester such as polybutylene terephthalate and polyethylene terephthalate (referred to as aromatic polyester in the present invention); polyphenylene sulfide. And polyolefins such as polyethylene and polypropylene; polyamides such as nylon 6, nylon 66, nylon 610, nylon 46, nylon 11, nylon 12, and the like, and these may be used in combination.

Polyacetal The type of polyacetal used in the present invention is not particularly limited, it may be a homopolymer or a copolymer, the copolymer may be a random or block, the type of comonomer, there is no limitation on the content, There is no particular limitation on the molecular weight, crystallinity, melting point, etc. of the polyacetal.
As the comonomer, a cyclic ether and / or cyclic formal is used. Specifically, 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin And the like, and 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide and the like are preferable.
Further, cyclic esters such as β-propiolactone, and vinyl compounds such as styrene are also used. Further, a compound having two or more polymerizable cyclic ether groups or cyclic formal groups such as alkylene-diglycidyl ether or diformal can be used as a comonomer for forming a branched or crosslinked molecular structure in the copolymer. . For example, butanediol dimethylidene glyceryl ether, butanediol diglycidyl ether and the like can be mentioned.
The amount of the comonomer is 0.1 to 20 mol%, preferably 0.2 to 10 mol%, based on trioxane.
Examples of the molecular weight include those having a number average molecular weight of 10,000 to 100,000, preferably 20,000 to 80,000; and a molecular weight distribution of 4 or less, preferably 2 to 3.
The degree of crystallinity varies depending on the type of polymer, but is usually 50 to 90%, preferably 60 to 80%.
Various commercially available resins can be used as the above resin.

Aromatic polyester The type of the crystalline aromatic polyester used in the present invention is not particularly limited, and may be a homopolymer or a copolymer, the copolymer may be random or a block, and the type and content of the comonomer. The amount is not limited, and the molecular weight, crystallinity, melting point and the like of the aromatic polyester are not particularly limited.
Examples of the aromatic polyester include alkylene aromatic dicarboxylates such as polyethylene terephthalate, polybutylene terephthalate (PBT), and polyethylene naphthalate.
Examples of the aromatic polyester include, for example, an aromatic dicarboxylic acid component (such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid) and an alkylene glycol in which at least one component is another dicarboxylic acid (comonomer) or another diol (comonomer). And the like.
These aromatic polyesters can be used alone or in combination of two or more.
Examples of the diol component (comonomer component) include alkylene glycols having about 2 to 12 carbon atoms, for example, ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, octanediol, decamethylene glycol, neopentyl glycol, Examples thereof include aliphatic glycols having about 2 to 10 carbon atoms, such as 1,3-octanediol.
These diol components may be used alone or in combination of two or more.
The melting point and molecular weight of the aromatic polyester are not particularly limited as long as they can be molded and form spherulites upon solidification.
Various commercially available resins can be used as the above resin.

Polyolefin Examples of the polyolefin include polyethylene, polypropylene, poly-4-methylpentene-1, and a copolymer thereof. Among them, those having stereoregularity may be isotactic or syndiotactic. In addition, polymerization catalysts were polymerized by multi-site type catalysts such as Ziegler-Natta catalysts, or polymerized by single-site type catalysts such as metallocene catalysts such as Kaminsky catalyst or phenoxyimine complex catalysts. It doesn't matter.
Various commercially available resins can be used as the above resin.

Polyarylene sulfide Examples of the polyarylene sulfide include polyphenylene sulfide. As polyphenylene sulfide, a p-phenylene sulfide group is used as a main repeating unit, and a linear type, a branched type, a cross-linked type, or a mixture thereof, with a repeating unit such as an m-phenylene sulfide group. It may be a copolymer. Various commercially available resins can be used as the above resin.

Polyamide Examples of the polyamide include polyamides such as aromatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 46, nylon 11, nylon 12, and nylon 6T. Various commercially available resins can be used as the above resin.

Resin additive A stabilizer, a crystallization accelerator (nucleating agent), a release agent, a conductivity imparting agent, and the like may be added to the resin.
As the stabilizer, for example, various hindered phenolic antioxidants and the like are used. For example, 2,6-di-t-butyl-4-methylphenol, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexane Diol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxyhydrocinnamide), 2-tert-butyl-6- (3'-tert-butyl-5'-methyl-2 ' -Hydroxybenzyl) -4-methylphenyl acrylate, 3,9-bis [2-{(3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1'-dimethyl Chill] -2,4,8,10-spiro [5,5] - undecane, and the like.

Filler An organic or inorganic filler, glass fiber, carbon fiber, metal fiber, whisker, carbon nanotube, carbon nanoparticle, or the like may be added to the crystalline polymer.
The filling amount of the reinforcing material such as glass fiber is 50 parts by weight or less, preferably 1 to 30 parts by weight, based on 100 parts by weight of the crystalline polymer.

Molded articles Examples of the method for molding the crystalline polymer include injection molding, hollow molding, extrusion molding, blow molding, and foam molding.
The use of the molded article is not particularly limited, and includes electric / electronic parts, automobile / transportation equipment, general / precision machinery, building materials, medical parts, and others.

Soft etching method (S)
In the conventional general etching method, since the surface is uniformly roughened, the spherulite morphology near the fracture surface required for analysis in the present invention is destroyed. Therefore, a soft etching method that does not destroy the spherulite morphology near the fracture surface is required.
The soft etching method (S) differs depending on the type of the polymer material, and includes a method using ultraviolet light of a specific wavelength (S1), a method using hydrolysis (S2), a method using an acid (S3), a method using a base (S4), A method using a solvent (S5), a method using an oxidizing gas such as ozone (S6), a method using a reducing gas such as hydrazine (S7), a method using discharge (S8), a method using electron beam irradiation (S9), plasma Examples include a method by irradiation (S10), a method by other particle beam irradiation (S11), a method by X-ray or γ-ray (S12), and a combination of two or more of these.

(I) A method using ultraviolet light of a specific wavelength (also referred to as UV etching treatment)
Hereinafter, the UV etching process will be described using polyacetal as an example.
The etching of the broken surface of the damaged molded product is performed by irradiating the broken surface with ultraviolet rays having a wavelength of preferably 300 nm or less (also referred to as a UV etching process). In this case, it is necessary to etch the fractured surface without damaging the characteristic shape of the fractured surface. Specifically, irradiation is performed so that a spherulite form immediately below the fracture surface appears while maintaining the pattern of the fracture surface. If the wavelength is longer than 300 nm, the polyacetal may not be easily etched.
The UV etching treatment may be performed on the fractured surface of the molded article itself. However, when observing the change before and after etching using the same sample, after observing the fractured surface on which the metal is primarily deposited by SEM, SEM sample for observing the fracture surface after etching by irradiating ultraviolet rays and etching the primary vapor-deposited fracture surface to form a spherulite just below the fracture surface and further depositing metal secondarily And

The kind of metal to be deposited is usually used for preparing a sample for SEM, and specific examples thereof include gold, platinum, palladium, and a mixture thereof. The primary metal and the secondary metal may be the same or different.
The thickness of the metal to be first-deposited is preferably 3 to 12 nm, more preferably 8 to 10 nm. If the thickness of the primary deposited metal is too thicker than the above range, it becomes difficult to perform etching treatment by ultraviolet irradiation. If the thickness is smaller than the above range, the sample deposited by the primary deposition is charged when observed by SEM, and the observation becomes impossible. In addition, the sample is damaged by the electron beam.
The thickness of the metal to be secondarily deposited can be arbitrarily determined as long as it is within a range observable by SEM. However, if the treatment time is long, the fracture surface may be destroyed by metal ions, so that the thickness cannot be made too large, and is preferably 12 to 16 nm.
If the thickness of the metal to be secondarily deposited is too thick, the morphology of spherulites is difficult to observe.
The solvent to be washed is one that does not dissolve the fractured surface of the molded article and varies depending on the type of the polymer material, and examples thereof include acetone, methanol, hexane, and fluorocarbons.

By the etching treatment, the amorphous portion of the polyacetal is preferentially removed over the spherulite portion.
The etching depth of the fracture surface is 1 to 30 μm, preferably 10 to 20 μm.
If the etching depth is too shallower than the above range, it is not known whether a spherulite layer exists immediately below the fractured surface. If the etching depth is too deeper than the above range, the pattern of the fractured surface is easily lost.
Since the sample after the primary vapor deposition is etched using the above-mentioned ultraviolet light, the irradiation condition of the ultraviolet light to the fracture surface of the molded product depends on the kind and thickness of the metal to be vapor-deposited, but 5 to 20 mW / cm ² , The irradiation time is preferably 8 to 10 mW / cm ² , and the irradiation time is 30 to 90 minutes, preferably 40 to 70 minutes.
If the irradiation amount of ultraviolet rays to the fracture surface is less than the above range, sufficient etching is not performed, and if it exceeds the above range, the etching proceeds too much and the spherulite portion changes too much, and a desired pattern for analyzing the fracture surface is obtained. I can't.
The light source for irradiating the ultraviolet rays is not particularly limited, and examples thereof include a lamp using resonance lines of metal atoms such as a medium-pressure or low-pressure mercury lamp, and a halogen lamp such as an yoso lamp.
By using ultraviolet light, the surface is mildly etched without excessively increasing the surface temperature, so that the fracture surface is etched without losing the characteristic shape of the fracture surface, and the spherulites just below the fracture surface Can appear. On the other hand, in the case of polyacetal, when etched by corona discharge, plasma, etc., the surface is easily melted and the characteristic shape of the fracture surface is easily damaged, so it is important to select an appropriate etching method for each resin material It is.

(II) Etching with a base (also referred to as etching with a basic solution)
Hereinafter, a method of performing an etching treatment with a basic solution and a pretreatment by irradiating ultraviolet rays and then performing an etching treatment with a basic solution will be described using an aromatic polyester as an example.

(1) Etching treatment with basic solution In the present invention, the fracture surface of the aromatic polyester molded article is treated with a basic solution, and the fracture surface is etched without impairing the characteristic shape (fracture surface pattern) of the fracture surface. The spherulite just below the fracture surface appears.
Examples of the base include alkali metals such as lithium, sodium, and potassium or alkaline earth metals such as calcium, magnesium, and barium, and hydroxides, oxides, carbonates, and bicarbonates thereof. Or their hydroxides.
Examples of the basic solution used in the present invention include an alcoholate solution of an alkali metal, an alcohol solution of a hydroxide of an alkali metal or an alkaline earth metal (abbreviated as alkali hydroxide), and an aqueous solution of an alkali hydroxide. .
When an aqueous solution is used, it is considered that the method (S2) by hydrolysis is simultaneously occurring as a soft etching method, and the embodiment thereof is also included.
Examples of the alcohol include methanol, ethanol, isopropanol, n-propanol, butanol, pentanol, hexanol and the like, and preferably methanol, ethanol or a mixture thereof. Further, the alcohol may be a hydrated alcohol.
The concentration of the base is 1 to 10% by weight, preferably 5 to 10% by weight.
The treatment temperature with the basic solution is 0 to 100 ° C., preferably 5 to 40 ° C., usually room temperature, and the treatment time is 0.2 to 10 hours, preferably 0.5 to 5 hours, more preferably 3 to 4 hours. Time. The treatment pressure may be atmospheric pressure, but is not particularly limited from vacuum to pressurized if necessary.
If the alkali concentration, temperature and time are less than the above ranges, decomposition of the fractured surface becomes insufficient, and if it is more than the above range, the decomposition proceeds excessively and the characteristic shape of the fractured surface is impaired.

(2) Pretreatment method by ultraviolet irradiation The basic solution treatment of the fractured surface may be performed as it is on the fractured surface of the molded article. However, when the pretreatment by ultraviolet radiation is performed, the morphology of spherulites becomes clear. Is preferred.
The pretreatment is performed by irradiating the fracture surface with ultraviolet rays having a wavelength of 300 nm or less (also referred to as UV pretreatment). If the wavelength is too long, the pretreatment of the polyester may be difficult to perform.
The UV light source is the same as that described in the section on the UV etching of the polyacetal.
When the UV pretreatment is performed, the affinity of the fracture surface to the basic solution is improved, so that the appearance of the spherulite morphology becomes clearer than the treatment with the basic solution alone.
The conditions for the basic solution treatment are a concentration of 1 to 10% by weight, a temperature of room temperature, and a time of 0.5 to 5 hours depending on the fracture surface pattern.

The basic solution treatment after the UV pretreatment may be performed on the fractured surface of the molded article itself, or when observing a change before and after the treatment using the same sample, the metal is preferably used in an amount of 3 to 12 nm. After observing the fractured surface which has been firstly deposited to a thickness by SEM and irradiating with UV, the fractured surface is treated with a basic solution, and the fractured surface which has been primarily deposited is etched to form a sphere immediately below the fractured surface. A crystal form appears, and a metal is further vapor-deposited, preferably to a thickness of 12 to 16 nm, to obtain a sample for SEM for fracture observation after the basic solution treatment.
The type of metal to be deposited and the primary and secondary deposition methods are the same as those described in the section on the UV etching of polyacetal.

By the above-mentioned basic solution treatment or by the basic solution treatment after the UV pretreatment, the amorphous portion of the polyester is preferentially removed from the spherulite portion.
The etching depth of the fracture surface is 1 to 8 μm, preferably 1 to 5 μm. If the etching depth is too shallower than the above range, it is not known whether a spherulite layer exists immediately below the fractured surface. If the etching depth is too deeper than the above range, the pattern of the fractured surface is easily lost.
Since the sample after the primary deposition is etched with the basic solution after the above-mentioned UV irradiation, the UV irradiation conditions for the fracture surface of the molded product depend on the type and thickness of the metal to be deposited, but 5 to 20 mW / cm ² , preferably 8 to 10 mW / cm ² , and the irradiation time is 30 to 90 minutes, preferably 40 to 70 minutes.
If the UV irradiation amount on the fracture surface is less than the above range, sufficient pretreatment is not performed, and if it exceeds the above range, the pretreatment progresses too much and the spherulite portion changes too much, and a desired pattern for analyzing the fracture surface is not obtained. I can't get it.
In PBT, when etched by corona discharge, plasma, or the like, the surface is melted, and the characteristic shape of the fracture surface is easily damaged.

Observation method The observation method includes the following.
Observation of the conventional fracture surface by SEM (O).
Observation of morphology of spherulites directly below the fracture surface from the fracture surface by SEM (A), particularly observation of morphology of spherulites immediately below the fracture surface from the fracture surface using a soft etching method (S) (1) .
Observation of the morphology of spherulites near the fracture surface (depth from the fracture surface to 100 μm) of the fracture surface cross section (B), in particular, observation of the morphology of spherulites near the fracture surface of the fracture surface cross section by a polarizing microscope (2), And / or SEM morphology observation of a spherulite near the fracture surface of the fracture surface cross section using a soft etching method (S) (3).
The SEM observation conditions are not particularly limited, and ordinary resin surface analysis conditions are used, and a normal metal deposition method is used.
The observation by the polarizing microscope may be orthoscopic observation or conoscopic observation, but is preferably orthoscopic observation.

Analysis of Fracture Surface In order to investigate the cause of destruction of a molded product, it is desirable to first grasp the failure status and then proceed to observation of the fracture surface in order to enhance its reliability.
The key to the observation of the fracture surface is (a) the point of occurrence of the fracture, (b) the presence or absence of a substance considered to be a defect at the point of occurrence of the fracture, and (c) the type of stress that caused the fracture.
The molded article contains more or less factors that may cause a defect, but when stress is applied thereto, the defect is a starting point and is likely to be damaged. In order to produce molded articles, it is necessary to understand the factors that may cause defects, design and molding to avoid them, and in the event of breakage, understand the cause and consider improvement measures. Start out.
Classification of the damage and the cause of the molded article that had a damage problem is as follows.
[Destruction point / defect]: [Main cause]
Sharp corner: Stress concentration Flow mark / hot water wrinkle: Stress concentration Weld: Poor adhesion / low elongation Gate: Low elongation / forming strain Burr: Poor plasticization / cold slag causing notch generation: Stress concentration at the boundary Other resin / foreign matter contamination: Stress concentration occurs at the boundary. Thick part with a slender core: Blowing due to insufficient cooling. Thickness sudden change: Molding strain. Thin part: Physical anisotropy due to flow orientation. Depending on the type of load, for example, static load, impact load, or cyclic load, a characteristic fracture surface pattern can be obtained, and the external factor that caused the failure by comparing it with the fracture surface form of the damaged product Can be estimated.

Typical pattern of fracture surface The fracture surface of a damaged molded product is classified into a ductile fracture surface, a fatigue fracture surface, a brittle fracture surface, a creep fracture surface, a shear fracture surface, a corrosion degradation fracture surface, and the like.

(I) Typical pattern of fractured surface of polyacetal
(i) Static Ductile Surface In the static ductile fracture surface of “Duracon”, a dimple pattern and a stripe pattern in the dimple (also called a striation pattern) are observed around the starting point (see FIGS. 6 and 7). ).
(ii) Fatigue fracture surface The fatigue fracture surface of “Duracon” is usually observed in two different patterns (see FIGS. 26 and 27).
One is a striped pattern that is generated by repeating the progression and stagnation of cracks in response to the control of the load (see FIG. 27).
The other is a form of brittle fracture in which the fatigue crack reaches the limit and breaks all at once, and when focusing only on this portion, it is similar to the pattern of the brittle fracture surface (see FIG. 26).
(iii) Brittle fracture Impact fractures account for the largest percentage of molded article failures.
The fracture surface due to the impact fracture is a brittle fracture surface, and by observation of the fracture surface (O), the pattern of the fracture surface is observed as a radial pattern (river pattern) centered on the starting point and a scale-like pattern (FIG. 1). 3). Therefore, by carefully observing the entire fractured surface with the naked eye, a loupe, or the like, and following the radial pattern in reverse, the point of occurrence and the state of progress of the fracture can be relatively easily grasped.
(iv) Creep rupture surface The creep rupture surface broken by the static load applied for a long time is very ductile and shows a fibrous characteristic pattern (see FIG. 28).
(v) Shear fracture surface The fracture surface due to punching shear shows a relatively smooth pattern (see FIG. 29).
(vi) Corrosion-degraded fracture surface "Duracon" is easily decomposed by acid, and is characterized by a degraded fracture surface (see FIG. 30).

(II) Representative pattern of fracture surface of aromatic polyester

  FIG. 31 shows an electron micrograph of the surface of the test piece that was solidified by melting the PBT molded product at 240 ° C. and then cooling it to room temperature at a rate of 10 ° C./min. As can be seen from FIG. 31, the granular one is a spherulite. The diameter of the spherulite of PBT is approximately several μm.

Typical pattern of Duranex (PBT)
(i) Brittle fracture surface A smooth region is observed at the starting point, and a radial pattern (river pattern) is observed around the region (see FIGS. 32, 33, and 34).
(ii) Static Ductile Fracture The static ductile fracture has a different fracture surface pattern when there is a defect such as a notch and when there is no defect.
(ii-1) Static Ductile Fracture Surface with Defects A small dimple pattern (lotus leaf-like pattern) appears densely over the entire fracture surface (see FIGS. 39 to 41).
(ii-2) Static ductile fracture surface in the absence of defects The specimen fractured with necking in a wide area, and a large mortar-shaped dimple pattern appeared on the fracture surface, and a stripe pattern in the dimple A pattern is observed (see FIGS. 46-48).
(iii) Fatigue fracture surface A slightly smooth small dimple pattern (lotus leaf-like pattern) appears densely over the entire fracture surface. (See FIGS. 53-56).
Very similar to a static ductile fracture surface with defects. When the small dimple pattern is enlarged near the end of the fracture surface, a stripe pattern (striation pattern) is observed in the dimple pattern or at the boundary between adjacent dimples (see FIGS. 57 to 59).
(iv) Creep fracture surface A slightly smooth small dimple pattern (lotus leaf-like pattern) appears densely over the entire fracture surface (see FIGS. 67 and 68).

By the basic solution treatment or the basic solution treatment after the UV pre-treatment, the surface is mildly etched without excessively increasing the surface temperature, so that the fractured surface is etched without impairing the characteristic shape of the fractured surface. Thus, it is possible to make a spherulite form just below the fracture surface appear.
(Example)

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
<Equipment used>
・ Surface treatment: manufactured by Sen Engineering Co., Ltd., UV surface modification device PL8-200 (main wavelength: 185 nm and 254 nm, output: 200 W)
-Electron microscope: Scanning electron microscope S-2700 manufactured by Hitachi, Ltd.
・ Evaporation equipment: Ion sputtering equipment E1030, manufactured by Hitachi, Ltd.
-Polarizing microscope: Polarizing microscope BH-2 manufactured by Olympus Optical Co., Ltd.
・ Microtome: Rotary microtome manufactured by Daiwa Koki Kogyo Co., Ltd.

Observation method (O) Observation of fracture surface by scanning electron microscope (A) Observation of morphology of spherulite just below fracture surface from fracture surface In particular, (1) Microstructural observation of fracture surface just below fracture surface by SEM (B) Observation of morphology of spherulite near fracture surface of fracture surface cross-section In particular, (2) Microstructure observation of fracture cross-section by polarization microscope In particular, (3) SEM observation of soft-etched cross-section The observation result of the fracture surface by the electron microscope is described in addition to the observation results of (1) to (3).

[I] Example of analysis method for fracture surface of polyacetal Intelligible, ductile fracture surface (i) obtained by statically ductile fracture of a non-reinforced polyacetal molded product by tensile fracture test, and fatigue fracture by gear fatigue durability test The fatigue fracture surface (ii) and the brittle fracture surface (iii) of the sample brittlely fractured by the Izod impact test were analyzed using the above observation method.

Hereinafter, an example of analysis using the above observation method will be described for each fractured surface.
(1) Scanning Electron Microscope Observation of the Fracture Surface of the Soft Etching Treatment The fracture surface of the sample used has different characteristic fracture surface patterns as shown below.
(i) Static Ductile Fracture: A dimple pattern in the starting region and a striped pattern in the dimple are observed (see FIGS. 6 and 7).
(ii) Fatigue fracture surface: A stripe pattern is observed (see FIGS. 10 and 11).
(iii) Brittle fracture surface: A radial pattern (river pattern) and a scale-like pattern are observed (see FIGS. 1 to 3).
The ductile striped pattern (i) and the fatigued striped pattern (ii) are very similar and are one of the patterns that are very difficult to discriminate and easily mistaken as long as the fracture surface is observed as it is.
As a condition for the etching, a structure immediately below the fractured surface must appear while these patterns are maintained.

Since polyacetal is a material that is degraded by ultraviolet light, ultraviolet irradiation (S1) using a short-wavelength UV irradiation device was used as an etching method. Since it is necessary to compare the change of the fracture surface before and after etching with the same fracture surface, first, the fracture surface before etching is observed with an SEM, and a photograph of the fracture surface is taken. When observing an insulator by SEM, metal deposition is performed on the observation surface to prevent electrification. Here, platinum-palladium is vapor-deposited. Further, in normal observation, vapor deposition is performed for about 130 seconds. However, since it is important to observe changes in the fracture surface before and after etching with the same fracture surface, primary vapor deposition was performed to perform observation before etching. The fracture surface must be etched. Therefore, the deposition time for unprocessed observation before etching was reduced to 80 seconds.
Next, the etching process will be described. First, the fractured surface used for the primary vapor deposition and SEM observation is ultrasonically cleaned in an acetone solvent. After washing, the air-dried sample is set in a UV irradiation device with the fracture surface for UV irradiation facing up. The distance from the light source is set to 40 mm, the irradiation time is set to 70 minutes, or in the case of brittle fracture, set to 60 minutes. After UV irradiation, the sample is taken out, washed with acetone, and platinum-palladium is secondarily deposited. When the same place observed before the etching treatment on the etched fracture surface is observed with an electron microscope, a state in which a spherulite form appears is observed.
Each of the fractured surfaces is subjected to the etching treatment of the fractured surface according to the above procedure.

The observation result seen from the fracture side of the etching fracture surface of each fracture surface is shown.
(i) Static ductile fracture (see FIGS. 8 and 9)
・ A state in which the spherulite is largely plastically deformed is observed on the entire fracture surface.
The striped pattern is a portion in which spherulites are greatly deformed and gaps (cracks) are generated due to displacement between spherulites.
(ii) Fatigue fracture surface (see FIGS. 12 and 13)
-There is no significant deformation of the spherulite, and the shape of the spherulite is observed.
-The striped pattern is a crack generated in the spherulite.
(iii) Brittle fracture surface (see FIGS. 4 and 5)
・ Undeformed spherulites appeared on the entire fracture surface. This suggests that the fracture occurred without plastic deformation of the spherulites.
From the above results, it was clarified that the state of the etched fracture surface was different between the static ductile fracture surface, the fatigue fracture surface, and the brittle fracture surface of the unreinforced polyacetal, which are difficult to distinguish.

(2) Observation of the microstructure of the cross section of the fracture surface using a polarizing microscope The cross section of the fracture surface of each fractured product embedded in epoxy resin is cut with a microtome to create a thin film of about 10 μm. An orthoscopic observation is made on the thin film using a polarizing microscope. The microstructure observation result of the cross section of each fractured surface is shown.
(i) Static ductile fracture (see FIGS. 14 and 15)
・ Under the fracture surface, the spherulites undergo large plastic deformation like rice ears, and no circular spherulites are observed.
-There is a shift between the plastically deformed spherulites.
(ii) Fatigue fracture surface (see FIGS. 16 and 17)
-A spherulite shape without large plastic deformation is observed just below the fracture surface.
・ Fracture occurs inside or between spherulites.
-Multiple streaks (cracks) are observed in one spherulite.
(iii) Brittle fracture surface (see FIGS. 18 and 19)
-Spherulite shape is observed immediately below the fracture surface.
・ Fracture occurs within or between spherulites.
・ Fracture occurs without plastic deformation of spherulite.
From the above results, in the microstructure observation of the cross section of the fracture surface, the state of the spherulite structure just below the fracture surface is different between the static ductile fracture surface and the fatigue fracture surface, as in the observation result of the etching fracture surface. It became clear.

(3) UV Etching Observation of Cross Section of Fracture Surface In the observation of (2), the same section as the fracture surface is subjected to UV etching on the cross section cut by the microtome. At this time, the irradiation time is set to 80 minutes, which is longer than the 60 minutes performed on the fracture surface. After the irradiation, the cut surface is washed with acetone and platinum-palladium deposited, and then the SEM observation of the etched cross section is performed. The observation result of the UV etching cross section of each fracture surface is shown.
(i) Static ductile fracture (see FIGS. 20 and 21)
・ Under the fracture surface, the spherulites undergo large plastic deformation like rice ears, and no spherulites are observed.
-A gap (crack) is generated between spherulites that have undergone large plastic deformation.
(ii) Fatigue fracture surface (see FIGS. 22 and 23)
-A spherulite shape without large plastic deformation is observed just below the fracture surface.
・ Fracture occurs inside or between spherulites.
(iii) Brittle fracture surface (see FIGS. 24 and 25)
-Spherulite shape is observed immediately below the fracture surface.
・ Fracture occurs within or between spherulites.
・ Fracture occurs without plastic deformation of spherulite.
From the above results, it was revealed that the state of the spherulite structure immediately below the fracture surface differs between the static ductile fracture surface, the fatigue fracture surface, and the brittle fracture surface also in the observation of the UV-etched cross section.
The following is clarified by summarizing the observation of the UV etching fracture surface, the observation of the microstructure of the fracture surface cross section, and the observation of the UV etching cross section.
(i) Static Ductile Fracture / Dimples in a static ductile fracture are fractures accompanied by large plastic deformation of spherulites.
A striped pattern is a gap (crack) between spherulites caused by a shift of the spherulites.
(ii) Fatigue fracture / Fatigue fracture is a fracture that occurs within or between spherulites without large plastic deformation of the spherulites.
The striped pattern is a crack generated in each spherulite due to repeated fatigue.
(iii) Brittle fracture / brittle fracture is a fracture within or between spherulites without plastic deformation of the spherulites.

The results of the spherulite morphology analysis just below the fracture surface by the above observation method show that the mechanism of the fracture surface pattern is different between the static ductile fracture surface and the fatigue fracture surface of polyacetal, and it is clear that the fracture mode can be distinguished. It became.
Therefore, even if it is difficult to determine the fracture pattern by simply observing the fracture surface as it is and cannot determine the fracture mode, if the sample is a crystalline polymer material having a spherulite structure, the etched fracture surface and fracture surface cross section It has been clarified that it can be an effective means to determine a fracture mode by making a fracture surface pattern that is difficult to discriminate.

[II] Example of Analysis Method for Fracture Surface of Aromatic Polyester A plain, unreinforced polybutylene terephthalate (PBT), Duranex ^™ 2002 (manufactured by Polyplastics Co., Ltd.) molded article test piece was used for Izod Brittle fracture surface (i) fractured by impact test, static ductile fracture surface (ii) fractured by bending fracture test (with and without defect (ii-1) and (ii-2) The fracture surface (iii), which was broken by the tensile fatigue test, was analyzed using the above-mentioned observation method, similarly to the above-mentioned polyacetal.

Basic solution A 10% by weight solution of sodium hydroxide in ethanol was prepared using sodium hydroxide (reagent grade) and ethanol (reagent grade), and the solution was replaced with nitrogen and stored in a dark place.
UV pretreatment See polyacetal section above.

Using a sample in which platinum-palladium is primary-deposited to a thickness of 8 nm on the fracture surface, a pattern is observed by SEM, and the sample is ultrasonically washed in an acetone solvent. The air-dried sample is set in a short-wavelength UV irradiator with the fracture surface for UV irradiation facing up. The distance from the light source is set to about 30 mm, the irradiation time is set to 60 minutes, and UV irradiation is performed to perform pretreatment.
Then, it is immersed in the above basic solution at room temperature for 4 hours for brittle fractures and 1 hour for static ductile fractures and fatigue fractures. After taking out the sample, washing with water and washing with acetone, platinum-palladium is secondarily deposited. The etching fracture surface is observed with an electron microscope. Each of the fractured surfaces is subjected to the etching treatment of the fractured surface according to the above procedure.

(1) Scanning electron microscope observation of the fracture surface of the soft etching treatment The fracture surface of the sample used has different characteristic fracture surface patterns as shown below.
(i) Brittle fracture surface: A radial pattern (river pattern) is observed radially from the starting point (see FIGS. 32, 33, and 34).
(ii-1) Static Ductile Fracture Surface with Defects: A state in which small dimple patterns (lotus leaf-like patterns) are dense over the entire fracture surface appears (see FIGS. 39 to 41).
(ii-2) Static ductile fracture surface in the absence of defects: The specimen fractured with necking over a wide area, and a large mortar-shaped dimple pattern appeared on the fracture surface, with stripes in the dimples A pattern is observed (see FIGS. 46 to 48).
(iii) Fatigue fracture surface: A slightly smooth small dimple pattern (lotus leaf-like pattern) appears densely over the entire fracture surface (see FIGS. 53 to 56). When the small dimple pattern is enlarged near the end of the fracture surface, a stripe pattern (striation pattern) is observed in the dimple pattern or at the boundary between adjacent dimples (see FIGS. 57 to 59).
Since polybutylene terephthalate is a material degraded by a basic substance, the above-mentioned basic solution was used as an etching method. Pretreatment by irradiation with ultraviolet light is preferable because the spherulite becomes clear.
The observation result seen from the fracture side of the etching fracture surface of each fracture surface is shown.
(i) While the radial pattern (river pattern), which is a characteristic of brittle fracture / brittle fracture, is maintained, the spherulite (spheroidal petal pattern) that has not been deformed immediately below the fracture surface is broken. Appeared on the entire surface (see FIGS. 35 and 36). This suggests that the fracture occurred without plastic deformation of the spherulites.
(ii) Static ductile fracture
(ii-1) Statically ductile fracture when there is a defect. Radial cracks are generated from the center of small dimple pattern (lotus leaf pattern), and spherulites (spherulite petal pattern) appear just below the fracture surface. do not do. (See FIG. 42).
-A spherulite petal pattern appears under the crack (Fig. 43). This suggests that the deformation area immediately below the fracture surface is very narrow.
(ii-2) When there is no defect, spherulite (petal pattern of spherulite) does not appear under the static ductile fracture surface or just below the fracture surface. Cracks are formed along the striped pattern in the large mortar-shaped dimple pattern (see FIGS. 49 and 50).
(iii) Fatigue fracture ・ A crack is generated radially from the center of a small dimple pattern (lotus leaf pattern), and no spherulite (spherulite petal pattern) appears just below the fracture surface. (See FIGS. 60 and 61).
・ A spherulite petal pattern appears under the crack. This suggests that the deformation area immediately below the fracture surface is very narrow.
Cracks are generated along the stripe pattern (striation pattern) within the dimple pattern or between the dimple patterns (see FIGS. 62 and 63).
From the above results, it was clarified that the state of the fracture surface etched with respect to the static ductile fracture surface and the fatigue fracture surface when there was a defect was very similar.

(2) Observation of microstructure of cross section of fracture surface by polarization microscope Observation method is the same as that of polyacetal. The microstructure observation result of the cross section of each fractured surface is shown.
(i) A spherulite is observed immediately below the brittle fracture surface. The size of the spherulite is around 5 μm, which is smaller than that of polyacetal (see FIG. 37).
・ Fracture occurs without plastic deformation of spherulite.
(ii) Static ductile fracture
(ii-1) Static ductile fracture when there is a defect The spherulite is plastically deformed immediately below the fracture surface, and no circular spherulite is observed (see FIG. 44).
The area where the spherulites are plastically deformed is very narrow, about 10 μm.
・ Undeformed spherulites are observed below the narrow deformation region.
(ii-2) Static defect ductility when there is no defect The spherulite is plastically deformed in a wide area from immediately below the fractured surface, and no circular spherulite is observed.
・ A streak that seems to be a crack is observed immediately below the fracture surface (see FIG. 51).
(iii) Fatigue fracture surface (see FIGS. 64 and 65)
-The spherulites undergo plastic deformation immediately below the fracture surface, and no circular spherulites are observed.
The area where the spherulites are plastically deformed is very narrow, about 10 μm.
・ Undeformed spherulites are observed below the narrow deformation region.
・ Small cracks are formed in the spherulite deformation region.
-Several large cracks are formed inside the spherulite.
From the above results, in the microstructural observation of the fracture surface cross section, the state of the spherulite structure immediately below the fracture surface is similar to the observation result of the etching fracture surface in the static ductile fracture surface and the fatigue fracture surface in the case where there is a defect. It turned out to be very similar.

(3) Observation of Alkali Etching of Cross Section of Fracture Surface In the observation of (2), the cross section cut by the microtome is subjected to the same alkali etching as that of the fracture surface. At this time, the immersion time is 4 hours. Subsequent processing was performed in the same manner as in the above-mentioned polyacetal. The observation result of the alkali etching cross section of each fracture surface is shown.
(i) A spherulite (petal pattern of spherulite) is observed just below the brittle fracture surface. The size of the spherulite is around 5 μm, which is smaller than that of polyacetal. (See FIG. 38).
・ Fracture occurs without plastic deformation of spherulite.
(ii) Static ductile fracture
(ii-1) When there is a defect, a circular spherulite shape (petal pattern of spherulite) is not observed immediately below the static ductile fracture surface / fracture surface (see FIG. 45).
The area where the spherulites are plastically deformed is very narrow, about 10 μm.
・ Undeformed spherulites are observed below the narrow deformation region.
(ii-2) Static defect ductility when there is no defect The spherulite is plastically deformed in a wide area from immediately below the fractured surface, and no circular spherulite is observed.
・ A streak that seems to be a crack is observed immediately below the fractured surface (see FIG. 52).
(iii) Fatigue fracture surface (see Fig. 65)
-The spherulites undergo plastic deformation immediately below the fracture surface, and no circular spherulites are observed.
The area where the spherulites are plastically deformed is very narrow, about 10 μm.
・ Undeformed spherulites are observed below the narrow deformation region.
・ Small cracks are formed in the spherulite deformation region.
-Several large cracks are formed inside.
From the above results, it has been clarified that the state of the spherulite structure immediately below the fracture surface is very similar between the static ductile fracture surface and the fatigue fracture surface when there is a defect in the observation of the alkali-etched cross section.

When the above-mentioned observation of the fracture surface, observation of the microstructure of the fracture surface cross section, and observation of the alkali etching cross section of the PBT are summarized, the following becomes clear.
(i) Brittle fracture / brittle fracture is a fracture within or between spherulites without plastic deformation of the spherulites.
(ii) Static ductile fracture
(ii-1) Static ductile fracture surface when there is a defect. This is a fracture accompanied by local large deformation of spherulite of about 20 μm.
・ A small dimple (lotus leaf pattern) is a state in which multiple spherulites have undergone large radial deformation around the nucleus.
(ii-2) Fracture accompanied by large deformation of spherulite over a wide area in the depth direction from immediately below the static ductile fracture surface or fracture surface when there is no defect.
-Striped patterns are cracks between spherulites caused by large deformation of spherulites.
(iii) Fatigue fracture: This is a fracture accompanied by a large local spherulite deformation of about 20 μm.
・ A small dimple (lotus leaf pattern) is a state in which multiple spherulites have undergone large radial deformation around the nucleus.
The striped pattern is a crack formed between spherulites or inside a deformed spherulites due to fatigue action.

It is a scanning electron micrograph before the etching of a brittle fracture surface. 2 is a partially enlarged photograph of FIG. 1. 3 is a partially enlarged photograph of FIG. 2. It is a scanning electron micrograph after the brittle fracture surface is etched. 5 is a partially enlarged photograph of FIG. 4. It is a scanning electron micrograph of a static ductile fracture. 7 is a partially enlarged photograph of FIG. 6. It is a scanning electron micrograph after etching of a static ductile fracture. 9 is a partially enlarged photograph of FIG. 8. It is a scanning electron microscope photograph before etching of a fatigue fracture surface. It is the elements on larger scale of FIG. It is a scanning electron microscope photograph after etching of a fatigue fracture surface. It is a partial enlarged photograph of FIG. It is a polarizing microscope photograph of the cross section of a static ductile fracture. 15 is a partially enlarged photograph of FIG. 14. It is a polarization microscope photograph of the section of a fatigue fracture surface. 17 is a partially enlarged photograph of FIG. 16. It is a polarization microscope photograph of the section of a brittle fracture surface. 19 is a partially enlarged photograph of FIG. 18. It is a scanning electron micrograph after the etching of the cross section of a static ductile fracture surface. 21 is a partially enlarged photograph of FIG. 20. It is a scanning electron micrograph after the etching of the cross section of a fatigue fracture surface. 23 is a partially enlarged photograph of FIG. 22. It is a scanning electron micrograph after the etching of the cross section of a brittle fracture surface. 25 is a partially enlarged photograph of FIG. 24. It is a scanning electron microscope photograph of a fatigue fracture surface. 27 is a partially enlarged photograph of FIG. 26. It is a scanning electron micrograph of a creep fracture surface. It is a scanning electron microscope photograph of a shear fracture surface. It is a scanning electron microscope photograph of a corrosion deterioration fracture surface. FIG. 31 (a) is a scanning electron micrograph of the PBT test piece after melting and solidification. FIG. 31B is an enlarged photograph of the white frame portion in FIG. It is a scanning electron micrograph before etching of a brittle fracture surface. 33 is a partially enlarged photograph of FIG. 32. 34 is a partially enlarged photograph of FIG. 33. It is a scanning electron micrograph after etching of a brittle fracture surface. 36 is a partially enlarged photograph of FIG. 35. It is a polarization microscope photograph of the section of a brittle fracture surface. It is a scanning electron microscope after etching of a brittle fracture surface cross section. It is a scanning electron micrograph before etching of the static ductile fracture surface when there is a defect. It is a partial enlarged photograph of FIG. 41 is a partially enlarged photograph of FIG. 40. It is a scanning electron micrograph after etching of the static ductile fracture surface when there is a defect. 43 is a partially enlarged photograph of FIG. 42. It is a polarization microscope photograph of a section of a static ductile fracture surface when there is a defect. It is a scanning electron micrograph after etching of the static ductile fracture surface section when there is a defect. It is a scanning electron micrograph before etching of the static ductile fracture surface when there is no defect. 47 is a partially enlarged photograph of FIG. 46. 48 is a partially enlarged photograph of FIG. 47. It is a scanning electron micrograph after etching of the static ductile fracture surface when there is no defect. Fig. 50 is a partially enlarged photograph of Fig. 49. It is a polarizing microscope photograph of the cross section of a static ductile fracture surface when there is no defect. It is a scanning electron micrograph after etching of the static ductile fracture section in the case where there is no defect. It is a scanning electron micrograph before etching of a fatigue fracture surface. The background part is a sample table. FIG. 54 is a partially enlarged photograph of a white frame below FIG. 53; It is a partial enlarged photograph of FIG. It is a partial enlarged photograph of FIG. FIG. 54 is a partially enlarged photograph of a white frame on FIG. 53; 58 is a partially enlarged photograph of FIG. 57. 58 is a partially enlarged photograph of FIG. 58. It is a scanning electron micrograph after etching of a fatigue fracture surface. Fig. 61 is a partially enlarged photograph of Fig. 60. It is a scanning electron micrograph after etching of a fatigue fracture surface. 63 is a partially enlarged photograph of FIG. 62. It is a polarization microscope photograph of the section of a fatigue fracture surface. 65 is a partially enlarged photograph of FIG. 64. It is a scanning electron microscope photograph after etching of a fatigue fracture section. It is a scanning electron micrograph before etching of a creep fracture surface. 68 is a partially enlarged photograph of FIG. 67.

Claims (20)

  In the method for analyzing a fracture surface of a crystalline polymer material having a spherulite structure, observation of the fracture surface (O) and observation of the morphology of the spherulite immediately below the fracture surface from the fracture surface side (A) are performed by a scanning electron microscope. A fracture surface analysis method.   The fracture surface analysis method according to claim 1, further comprising using the morphology observation (B) of a spherulite near the fracture surface (depth from the fracture surface to 100 μm) of the fracture surface cross section.   The fracture surface analysis method according to claim 1 or 2, wherein the crystalline polymer having a spherulite structure is polyacetal, aromatic polyester, polyarylene sulfide, polyolefin, polyamide, or a mixture thereof.   The (i) ductile fracture surface, (ii) fatigue fracture surface, (iii) brittle fracture surface, (iv) creep fracture surface, or used for discriminating these composite fracture surfaces, according to any one of claims 1 to 3 Surface analysis method.   Morphological observation (A) uses a soft etching method (S) that makes the morphology of spherulites just below the fracture surface appear while maintaining the characteristic fracture patterns of various fracture modes. The fracture surface analysis method according to any one of claims 1 to 4, wherein the observation is a morphological observation (1) of a spherulite.   The morphological observation (B) is performed by observing the morphology of the spherulite in the vicinity of the fracture surface of the fracture surface using a polarizing microscope (2) and / or the fracture surface of the fracture surface using the soft etching method (S). The fracture surface analysis method according to any one of claims 1 to 5, wherein a morphological observation of a nearby spherulite by a scanning electron microscope (3) is performed.   The soft etching method (S) irradiates ultraviolet rays to the fractured surface of the polyacetal and etches the fractured surface without impairing the characteristic shape of the fractured surface, so that a spherulite form immediately below the fractured surface appears. The fracture surface analysis method according to claim 5, wherein (S1).   The fracture surface analysis method according to claim 7, wherein the wavelength of the ultraviolet light is 300 nm or less.   In the etching method (S1), the fractured surface of the metal was firstly vapor-deposited to a thickness of 3 to 12 μm on the fractured surface of the polyacetal, and the fractured surface was observed with a scanning electron microscope. 9. The fracture surface analysis method according to claim 7 or 8, wherein the fracture surface is etched to cause a spherulite form immediately below the fracture surface to appear.   The fracture surface analysis method according to claim 9, wherein an etching depth of the polyacetal portion is 1 to 20 μm. Irradiation conditions of the ultraviolet ray for fractures, fracture analysis method according to any one of claims 7 to 10 40 to 70 minutes 8~10mW / cm ^2.   The soft etching method (S) etches the fractured surface of the aromatic polyester using a basic solution without damaging the characteristic shape of the fractured surface, resulting in the appearance of spherulites just below the fractured surface The fracture surface analysis method according to claim 5, wherein the etching method is an etching method (S 4).   The fracture surface analysis method according to claim 12, wherein the basic solution is an alcohol solution of sodium hydroxide.   The fracture surface analysis method according to claim 12 or 13, wherein the basic solution is an alcohol solution having a concentration of 1 to 10% by weight, the treatment temperature is 5 to 40 ° C, and the treatment time is 0.5 to 5 hours.   The fracture surface analysis method according to any one of claims 12 to 14, wherein the fracture surface of the aromatic polyester is irradiated with ultraviolet light in advance and then treated with a basic solution. Irradiation conditions of the ultraviolet ray for moldings fractures, fracture analysis method according to any one of claims 12 to 15 30 to 90 minutes 8~10mW / cm ^2.   The fractured surface of the crystalline polyester resin molded product was subjected to primary vapor deposition of metal, observed with a scanning electron microscope, irradiated with ultraviolet light, treated with an alkali solution, and subjected to the primary vapor deposition. 17. A fracture surface analysis method according to any one of claims 12 to 16, wherein the surface is etched to reveal a spherulite form immediately below the fracture surface, and a metal is secondarily deposited to obtain a sample for a scanning electron microscope.   The fracture surface analysis method according to any one of claims 12 to 17, wherein the thickness of the primary deposited metal is 3 to 12 nm, and the thickness of the secondary deposited metal is 12 to 16 nm.   The fracture surface analysis method according to any one of claims 12 to 18, wherein the etching depth of the aromatic polyester is 1 to 5 m.   The fracture surface analysis method according to any one of claims 12 to 19, wherein the aromatic polyester is polybutylene terephthalate.