CN108099050B - Method for accelerating conversion from crystal form II to crystal form I by applying flowing shear to isotactic polybutene-1 structural melt - Google Patents
Method for accelerating conversion from crystal form II to crystal form I by applying flowing shear to isotactic polybutene-1 structural melt Download PDFInfo
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Abstract
The invention discloses a method for accelerating the transformation of a crystal form II to a crystal form I by applying flowing shear to a melt of a isotactic polybutene-1 structure. According to the method, a melt index instrument is used for preparing a structural melt of isotactic polybutene-1 at a certain temperature, and then the melt is extruded under the action of flowing shear, so that the obtained isotactic polybutene-1 crystal form II can be converted into the crystal form I in a short time. The method can accelerate the transformation of the isotactic polybutene-1 crystal form II to the crystal form I without adding any auxiliary agent, filler and the like in the preparation process, namely, the transformation of the isotactic polybutene-1 crystal form II to the crystal form I is accelerated, and meanwhile, the transparency, the purity and the like of the isotactic polybutene-1 are not influenced, so that the wide application of the excellent-performance polybutene-1 in various fields is obviously promoted, the production cost is reduced, and the social and economic benefits are good.
Description
Technical Field
The invention belongs to the technical field of polymer processing. Relates to a method for accelerating the transformation of a crystal form II to a crystal form I by applying flowing shear to a melt of a isotactic polybutene-1 structure. In particular to a method for accelerating the transformation of a crystal form II of isotactic polybutene-1 to a crystal form I through structural melt and flow shearing.
Technical Field
Isotactic polybutene-1, abbreviated as iPB-1, is a high isotactic polymer, thermoplastic high molecular material, has outstanding heat creep resistance, environmental stress cracking resistance, good toughness, durability, chemical stability and plasticity, is known as 'gold in plastics' due to excellent physicochemical properties, and is one of the most advanced chemical materials in the world at present. The excellent performance of the polybutene-1 makes the polybutene still have excellent mechanical performance under the heated condition, and the heat resistance of the polybutene-1 can make the polybutene be used under the condition of 80-110 ℃ for a long time. The polybutene-1 has both plastic and elastomer properties, and is suitable for use as modifier for hot water pipe, polyolefin, engineering plastic, etc. The pipe made of polybutene-1 has super acid resistance, alkali resistance, wear resistance, no water absorption and other properties, and is one of the most advanced plastic pipes.
Due to the polycrystalline property of the isotactic polybutene-1, a certain degree of trouble is brought to processing and production. Four isotactic polybutene-1 crystal forms are known, 31Helical chain piled crystal type I and I', 113Crystal forms II and 4 of spiral chain stacking1And the most common and most valuable crystal form III in the crystal form III stacked by the spiral chain is the crystal form II and the crystal form I. Under the common processing conditions, the prepared isotactic polybutene-1 product is directly cooled from high temperature to room temperature and crystallized under normal pressure to obtain the crystal form II, but the crystal form II is a metastable crystal form and can be spontaneously transformed to a more stable crystal form I, and the crystal form I obtained after transformation has excellent stability and wide application, but the transformation process needs about 7 to 14 days. Due to the crystal form transformation characteristic of the isotactic polybutene-1, the time cost is greatly increased, and the application of polybutene-1 products in various fields is greatly limited.
At present, in order to make polybutene-1 with excellent performance better applied, the technical research on crystal form transformation has been carried out, but most of the polybutene-1 with excellent performance adopts CO2The high pressure and the addition of fillers, additives and the like realize the rapid transformation of the crystal form, although the technologies have a promoting effect on the transformation of the polybutene-1 crystal form to a certain extent, the high pressure requirement conditions are harsh, and the addition of various additives and the like often has certain influence on the properties such as transparency, purity and the like, so that the application of the polybutylene terephthalate is still limited, and the polybutylene terephthalate cannot be well applied.
Disclosure of Invention
In order to solve the problems, the invention provides a method for accelerating the transformation from the crystal form II to the crystal form I by applying flowing shear to a melt with an isotactic polybutene-1 structure, which is simple and easy to operate, can accelerate the transformation from the crystal form II to the crystal form I of the polybutene-1 without adding any auxiliary agent and filler, does not damage the performance of the polybutene-1, can realize the transformation from the crystal form II to the crystal form I in a short time, and ensures that the product has stable performance.
The invention is realized by the following technical scheme
A method of accelerating the transformation of crystalline form ii to crystalline form i by applying flow shear to a melt of isotactic polybutene-1 structure, the method comprising the steps of: opening the melt index instrument, and setting a temperature program of the melt index instrument; after the temperature in a feeding cylinder of the melt index instrument is raised to a set temperature, taking isotactic polybutene-1 particles, adding the isotactic polybutene-1 particles into the feeding cylinder in the melt index instrument with a set temperature program through a feeding hopper, and carrying out heat treatment to obtain a melt of an isotactic polybutene-1 structure after the heat treatment is finished; and (2) applying flowing shear to the obtained isotactic polybutene-1 structural melt to extrude, cooling the extruded sample at room temperature, polishing the cooled sample into a sheet sample by using sand paper to obtain the isotactic polybutene-1 capable of being converted from the crystal form II to the crystal form I in a short time, and measuring the time for converting the crystal form II to the crystal form I.
The method for accelerating the transformation from the crystal form II to the crystal form I by applying flowing shear to the isotactic polybutene-1 structural melt is characterized in that the isotactic polybutene-1 structural melt is a near-melting point melt or a supercooled melt.
The method for accelerating the transformation from the crystal form II to the crystal form I by applying flow shear to the melt of the isotactic polybutene-1 structure is characterized in that the temperature program for setting the melt index instrument is the temperature required in the heat treatment process and the heating time corresponding to the temperature heating.
The method for accelerating the transformation from the crystal form II to the crystal form I by applying flowing shear to the melt of the isotactic polybutene-1 structure comprises the following specific heat treatment steps: adding the polybutene-1 particles into a feeding cylinder of a melt index instrument, and preheating for 2-3 min at 131-139 ℃; after preheating is finished, a weight is placed at the top end of the material rod to apply load, so that the material rod gradually moves downwards to discharge air among the isotactic polybutene-1 materials, and the materials after the air is completely discharged are continuously heated in the charging barrel for 3-5 min at the temperature of 131-139 ℃ to obtain the isotactic polybutene-1 near-melting-point melt.
The method for accelerating the transformation from the crystal form II to the crystal form I by applying flowing shear to the melt of the isotactic polybutene-1 structure comprises the following specific heat treatment steps: adding the isotactic polybutene-1 particles into a feeding cylinder of a melt index instrument, and preheating for 2-3 min at 180 ℃; after preheating is finished, weights are placed at the top end of a material rod of the melt index instrument to apply load, so that the material rod of the melt index instrument gradually moves downwards to discharge air among isotactic polybutene-1 materials, and the materials after the air is completely discharged are continuously heated for 3-5 min at 180 ℃ in a charging barrel; and after heating at 180 ℃, cooling to 131-139 ℃, and preserving heat for 8-10 min in a charging barrel at 131-139 ℃ to obtain the polybutene-1 supercooled melt.
The method for accelerating the transformation from the crystal form II to the crystal form I by applying flowing shear to the melt of the isotactic polybutene-1 structure is characterized in that the method comprises the following steps: after a weight is placed at the top end of the material rod of the melt index instrument, the material rod gradually moves downwards to discharge air among the materials of the isotactic polybutene-1, and when the materials can be seen from a die hole at the bottom of the melt index instrument, the air is completely discharged.
When a melt index instrument is used for carrying out heat treatment operation on a sample, firstly, the melt index instrument is opened to set the temperature, then, a neck mold and a material rod of the melt index instrument are placed in a charging barrel of the melt index instrument for preheating, when the temperature in the charging barrel of the melt index instrument rises to the set temperature, the neck mold and the material rod in the charging barrel are taken out, then, an isotactic polybutene-1 material is added from an upper end opening of the charging barrel, then, the material rod is rapidly placed in the charging barrel, and then, the material rod is preheated for a period of time at the set temperature; after preheating is finished, weights are placed at the top end of the material rod to apply load, so that the material rod gradually moves downwards to discharge air among materials until the materials can be seen from a die hole at the bottom of the melt index instrument, namely, the air is discharged, the weights at the top end of the material rod are taken down after the air is discharged, the materials are continuously heated for a period of time, namely, the heating process of the isotactic polybutene-1 is finished (if two sections of temperatures are required to be subjected to different heating treatments in the heating process, one temperature can be set on the melt index instrument, corresponding heating time is set, and then, other temperatures and heating time are set).
After the heating treatment is finished, a weight is placed at the top end of the material rod to apply load, so that the material moves downwards and is extruded under the action of the load (the extrusion process is accompanied with flow shearing under the action of certain shearing stress).
The method for accelerating the transformation of the crystal form II to the crystal form I by applying flowing shear to the melt of the isotactic polybutene-1 structure is characterized in that the shear force during shear flow is 45-90 KPa.
The structural melt comprises a near-melting-point melt and a supercooled melt; the polybutene-1 structural melt is the near melting point melt and the supercooled melt of polybutene-1.
The near-melting point melt is as follows: the polymer is directly heated to a certain temperature between the melting point and the equilibrium melting point, and locally ordered macromolecular groups exist, so that the polymer has a rich melt structure.
The supercooled melt is as follows: the polymer is heated to a temperature above the equilibrium melting point, the heat and mechanical history is completely eliminated, the polymer is cooled to a certain temperature, some ordered macromolecular groups are formed in the cooling process, and the melt structure is very rare.
The blank melt is as follows: the polymer is heated to above the equilibrium melting point, the heat and mechanical history is completely eliminated, and the molecular chain is in a completely disordered state.
Compared with the prior art, the invention has the following positive beneficial effects
The invention effectively promotes the transformation of the polybutene-1 crystal form II to the polybutene-1 crystal form I by combining the structural melt and the shear flow; the process is similar to the industrial process and is more easily combined with industrial production, and the invention does not add any auxiliary agent, filler and the like in the process of accelerating the crystal form transformation, maintains the physical and chemical properties of the material to the maximum extent and has no influence on the color, the state and the like of the material, so the method accelerates the application of the polybutene-1 in various fields to the maximum extent and does not increase any production cost.
The method for accelerating the crystal form transformation has the advantages of simple preparation process and convenient operation, greatly shortens the time of crystal form transformation and shortens the time cost; the crystal form transformation time is greatly shortened on the basis of not changing the basic physical and chemical properties of the polybutene-1, and the application of the excellent polybutene-1 in various fields is accelerated. Has good social and economic benefits.
Drawings
FIG. 1 is one of the schematic structural views of a melt index apparatus;
the symbols in the drawings indicate that: 1 denotes a weight, 2 denotes a material rod, 3 denotes a heating ring, 4 denotes a material cylinder, 5 denotes a plunger, 6 denotes an added material, 7 denotes a die, 8 denotes a die hole, and 9 denotes an extruded sample;
FIG. 2 is a graph of the transformation of form II to form I over time for extruded samples of isotactic polybutene-1 blank melt subjected to flow shear and static samples not subjected to flow shear;
FIG. 3 is a graph showing the transition of form II to form I over time for a blank melt and near-melting melt extruded samples of isotactic polybutene-1 subjected to the same flow shear;
FIG. 4 is a graph showing the time-dependent transition of form II to form I of a supercooled melt extruded sample of different melt states under the same flow shearing action applied to isotactic polybutene-1;
FIG. 5 is a graph showing the transformation of form II to form I of near-melting point melt extrusion samples of different melt states with time under the same flow shear applied by isotactic polybutene-1.
Detailed Description
The present invention will be described in more detail with reference to the following embodiments, but the scope of the present invention is not limited thereto.
The isotactic polybutene-1 particles used in the following examples are all from Liandbasel industries, Netherlands, where the isotactic polybutene-1 has a weight average molecular weight of 7.7X 105g/mol。
Comparative example 1
This example prepared an isotactic polybutene-1 blank melt as a control for an isotactic polybutene-1 structural melt prepared according to the present invention. The operation steps are as follows:
a flat hot plate, a glass slide (similar to the glass slide on a microscope), and a metal washer of a common nut were prepared.
Opening the flat plate heating table, setting the temperature to be 180 ℃, and simultaneously placing the glass slide and the metal gasket on the flat plate heating table from bottom to top in sequence; after the plate heat stage was warmed to 180 ℃ and stabilized for 20min, 3.5g of isotactic polybutene-1 particles were placed in a metal shim gasket (on top of the glass slide) and melted naturally to fill the hollow part of the gasket, and the melted sample was removed and cooled to room temperature (i.e., the sample was a blank melt without flow shear).
Grinding the cooled sample by 400-mesh, 600-mesh and 1000-mesh sand paper in sequence to obtain a sample with the thickness of 1mm, carrying out in-situ tracking on the conversion process of the isotactic polybutene-1 crystal form II to the crystal form I on the treated sample by adopting SAXS/WAXS, exposing once every 3-6 hours, collecting data within 72 hours, carrying out detection on the sample once in 21 days, deriving test data, and observing the peak intensity of the (200) crystal face characteristic peak of the crystal form II and the (110) crystal face characteristic peak of the crystal form I and the variation of the fitting peak area by using MDIJADA 5.0; as shown in fig. 2.
Comparative example 2
This example prepared a blank melt extrusion sample of isotactic polybutene-1 as a control for an isotactic polybutene-1 structural melt prepared according to the present invention. The operation steps are as follows:
(1) opening the melt index instrument, and setting the temperature of the melt index instrument to be 180 ℃; and simultaneously, placing the neck mold and the material rod into a charging barrel of a melt index instrument for preheating.
(2) When the temperature in the charging barrel of the melt index instrument rises to 180 ℃, taking out the neck mold and the material rod, adding 3.5g of isotactic polybutene-1 particles into the charging barrel, and preheating for 2 min; after preheating is completed, 1.835kg of weight is applied to the top end of the material rod, the material rod gradually moves downwards to discharge air among the isotactic polybutene-1 materials until the materials can be observed from a die hole at the bottom of the melt index instrument, the air is completely discharged (the time for discharging the air is 3-5 min), the load (the placed weight) applied to the top end of the material rod is taken down, and the materials are continuously heated in the material cylinder for 3-5 min to obtain the blank isotactic polybutene-1 melt.
(3) After the blank melt of the isotactic polybutene-1 is obtained after the heating in the step (2), 4.675kg of weight is applied to the top end of the material rod (the total applied load of the material rod, the weight and the plunger is 5kg), the material is extruded from a melt index meter die under the condition of flow shear (the extrusion temperature is 180 ℃), and the shear stress during the flow shear is 45 KPa; and cutting the extruded material once every 2-4 cm, and cooling at room temperature to obtain a cylindrical sample.
Grinding the cooled sample by 400-mesh, 600-mesh and 1000-mesh sand paper in sequence to obtain a sample with the thickness of 1mm, carrying out in-situ tracking on the conversion process of the isotactic polybutene-1 crystal form II to the crystal form I on the treated sample by adopting SAXS/WAXS, exposing once every 3-6 hours, collecting data within 72 hours, deriving test data, observing the peak intensity of the characteristic peak of the (200) crystal face of the crystal form II and the characteristic peak intensity of the (110) crystal face of the crystal form I, and fitting the change of peak area by using MDI JADA 5.0; as shown in fig. 2.
As can be seen from the results of fig. 2: after shear flow action is applied to the blank melt of the isotactic polybutene-1, the transformation degree of the crystal form II to the crystal form I is 33.5 percent when the transformation time is 36 hours in the transformation process; during the transformation of the crystal form II of the isotactic polybutene-1 blank melt without shear effect into the crystal form I, the transformation degree at 36 hours was 27%.
Example 3
A method of accelerating the transformation of crystalline form ii to crystalline form i by applying flow shear to a melt of isotactic polybutene-1 structure, the method comprising the steps of:
(1) opening the melt index instrument, setting the temperature program of the melt index instrument, setting the temperature to be 180 ℃, and setting the holding time of the temperature to be 10 min; then setting the temperature of the second section to be 131 ℃; after the temperature is set, placing the neck mold and the material rod into the charging barrel for preheating;
(2) when the temperature of the melt index instrument is increased to 180 ℃, taking out the neck mold and the material rod, quickly adding 3.5g of isotactic polybutene-1 particles into a charging barrel of the melt index instrument through a hopper, and preheating for 2 min; applying 1.835kg of weight to the top end of a material rod of the melt index instrument after preheating is finished, gradually moving the material rod downwards to discharge air among the isotactic polybutene-1 materials until the materials can be observed from a die hole at the bottom of the melt index instrument, namely the air is completely discharged (the air is completely discharged in 3-5 min), taking down the load loaded by the exhaust, and continuously heating the materials in a charging barrel at 180 ℃ for 3-5 min;
(3) after the heating in the step (2) is finished, cooling the temperature in a charging barrel of the melt index instrument to 131 ℃ according to the setting, and preserving the heat of the materials in the charging barrel for 10min under the temperature condition; thus obtaining the melt with the isotactic polybutene-1 supercooled structure;
(4) after the heating in the step (3) is finished to obtain the supercooled melt of the isotactic polybutene-1, applying 4.675kg of weight to the top end of the material rod (the total applied force of the weight, the material rod and the plunger reaches 5kg), extruding the material from a neck mold of a melt index instrument under the action of flow shearing (the extrusion temperature is 131 ℃), and the shear stress during the flow shearing is 45 KPa; cutting the extruded material for 2-4 cm once, and cooling at room temperature to obtain a cylindrical sample.
Grinding the cooled sample by 400-mesh, 600-mesh and 1000-mesh sand paper in sequence to obtain a sample with the thickness of 1mm, and then carrying out in-situ tracking on the processed sample by adopting SAXS/WAXS to carry out the conversion process from the isotactic polybutene-1 crystal form II to the crystal form I; in the detection tracking process, exposure is carried out every 3-6 hours in sequence, data within 72 hours are collected, test data are derived, the peak intensity of the characteristic peak of the (200) crystal face of the crystal form II and the characteristic peak of the (110) crystal face of the crystal form I are observed, and the change of the area of a fitting peak is adopted by MDIJADA 5.0.
The same method as the above example 3 is adopted, the temperature of 131 ℃ is changed to 135 ℃, and other operations are not changed to prepare the isotactic polybutene-1 supercooled melt structure sample; then setting the temperature to 139 ℃, and preparing the supercooled isotactic polybutene-1 supercooled sample without changing other operations. Respectively adopting SAXS/WAXS to track samples prepared at 135 ℃ and 139 ℃ in situ to obtain a transformation process of isotactic polybutene-1 crystal form II to crystal form I, exposing once every 3-6 hours, collecting data within 72 hours, deriving test data, observing the peak intensity of a (200) crystal face characteristic peak of the crystal form II and a (110) crystal face characteristic peak of the crystal form I, and fitting the peak area change by using MDI JADA5.0, wherein the transformation process is shown in figure 4.
The experimental results show that: when the isotactic polybutene-1 obtained under the combined action of the supercooled structural melt and the flow shearing condition and the crystal form II are transformed into the crystal form I: at the time of conversion for 36 hours, the conversion degree of the sample obtained at the temperature of 131 ℃ is 42.6 percent; the conversion degree of the sample obtained under the condition of 135 ℃ is 40.8 percent, and the conversion degree of the sample prepared under the condition of 139 ℃ is 38.4 percent, so that the conversion degree is obviously improved compared with that of the sample prepared by a blank melt.
Example 4
A method of accelerating the transformation of crystalline form ii to crystalline form i by applying flow shear to a melt of isotactic polybutene-1 structure, the method comprising the steps of:
(1) opening a melt index instrument, setting the temperature program of the melt index instrument, setting the temperature of the melt index instrument to be 131 ℃, and putting the neck mold and the material rod into the charging barrel for preheating;
(2) when the temperature of the material cylinder of the melt index instrument is raised to 131 ℃, taking out the preheated mouth mold and the material rod; weighing 3.5g of isotactic polybutene-1 particles, adding the particles into a charging barrel of a melt index instrument through a hopper, preheating for 2min at 131 ℃, applying 1.835kg of weight to the top end of a material rod of the melt index instrument after preheating is finished to discharge air among the isotactic polybutene-1 materials, and gradually moving the material rod downwards to discharge the air until the materials can be observed from a die hole at the bottom of the melt index instrument, namely completely discharging the air (3-5 min completely discharging the air); after the air is discharged, taking down a weight for applying a load to prevent the material rod from continuously moving downwards, and then heating the material in a feeding cylinder at 131 ℃ for 3-5 min to obtain a melt of the isotactic polybutene-1 near-melting point structure;
(3) after the heating in the step (2) is completed to obtain the near-melting-point structural melt, applying 4.675kg of weight to the top end of the material rod (the total applied force of the weight, the material rod and the plunger reaches 5kg), extruding the material from a neck mold of a melt index meter under the condition of flow shear (the extrusion temperature is 131 ℃), and the shear stress during the flow shear is 45 KPa; cutting the extruded material for 2-4 cm once, and cooling at room temperature to obtain a cylindrical sample.
Grinding the cooled sample by 400-mesh, 600-mesh and 1000-mesh sand paper in sequence to obtain a sample with the thickness of 1mm, carrying out in-situ tracking on the conversion process of the isotactic polybutene-1 crystal form II to the crystal form I on the treated sample by adopting SAXS/WAXS, exposing once every 3-6 hours, collecting frontal data within 72 hours in total, deriving test data, observing the peak intensity of the characteristic peak of the (200) crystal face of the crystal form II and the characteristic peak intensity of the (110) crystal face of the crystal form I, and fitting the peak area change by using MDI JADA 5.0.
Then, by the same method as in example 4, the same portions were not repeated, and the set temperature of 131 ℃ was changed to 135 ℃ and 139 ℃, and extruded samples in different melt states were prepared at 135 ℃ and 139 ℃. Then respectively adopting SAXS/WAXS to track the sample in situ to obtain the transformation process of the isotactic polybutene-1 crystal form II to the crystal form I, exposing once every 3-6 hours, collecting data within 72 hours in total, deriving test data, observing the peak intensity of the characteristic peak of the (200) crystal face of the crystal form II and the characteristic peak of the (110) crystal face of the crystal form I, and fitting the change of peak area by using MDI JADA5.0, wherein the results are shown in figure 3 and figure 5.
The experimental results show that: under the action of the same flowing shearing force, when the crystal form II is converted into the crystal form I for 36 hours, the conversion degree of a sample at 131 ℃ is 86.1 percent, the conversion degree of the sample at 135 ℃ is 77.1 percent, and the conversion degree of the sample at 139 ℃ is 55.3 percent; compared with the conversion degree of a blank melt static sample, the amplification degree reaches 218.9% at 131 ℃, 185.5% at 133 ℃ and 104.8% at 139 ℃. Namely, under the combined action of the near-melting-point structural melt and the flow shear, the crystal form transformation rate of the isotactic polybutene-1 is accelerated with remarkable effect.
From the above, it can be seen that: the method for accelerating the transformation of the isotactic polybutene-1 crystal form II into the isotactic polybutene-1 crystal form I can obviously improve the transformation from the isotactic polybutene-1 crystal form II to the isotactic polybutene-1 crystal form I without adding any auxiliary agent, filler and the like, particularly, the transformation degree of a sample obtained after the melt with a near-melting point structure obtained at the temperature of 131 ℃ is subjected to flow shearing reaches 86.1 percent in 36 hours, and the transformation degree is improved by two times compared with that of a static blank melt in 36 hours; in the later stage of conversion, the conversion rate is relatively slow, the static sample reaches 80 percent and needs about 500 hours, so that the time needed for stabilizing the performance of the product is saved by more than ten times; and the method of the invention can not cause any damage to the performance of the prepared isotactic polybutene-1 without adding any additive (for example, transparent isotactic polybutene-1 with good optical performance and capable of rapidly completing transformation can not be prepared), thereby greatly accelerating the application of the isotactic polybutene-1 with excellent performance.
The invention can be applied to the extrusion grade isotactic polybutene-1, does not add any additive, does not need harsh experimental conditions, remarkably accelerates the transformation from the crystal form II to the crystal form I, and is very beneficial to the industrial production and the large-scale application in various fields.
Claims (2)
1. A method for accelerating the transformation of crystal form II to crystal form I by applying flow shear to a melt of isotactic polybutene-1 structure, the method comprising the steps of: opening the melt index instrument, and setting a temperature program of the melt index instrument; when the temperature in a feeding cylinder of the melt index instrument is raised to a set temperature, adding isotactic polybutene-1 granules into the feeding cylinder of the melt index instrument with a set temperature program through a hopper for heat treatment, and obtaining an isotactic polybutene-1 structural melt after the heat treatment is completed; then, applying flowing shear to the obtained isotactic polybutene-1 structural melt for extrusion, cooling the extruded sample at room temperature, and then grinding the sample into a sheet sample by using abrasive paper;
the isotactic polybutene-1 structural melt is a near-melting point melt or a supercooled melt;
when the isotactic polybutene-1 structure melt is a near-melting point melt, the heat treatment specifically comprises the following steps: adding the isotactic polybutene-1 particles into a feeding cylinder of a melt index instrument, and preheating for 2-3 min under the condition of 131-139 ᵒ ℃; after preheating is finished, weights are placed at the top end of a material rod of the melt index instrument to apply load, so that the material rod gradually moves downwards to discharge air among isotactic polybutene-1 materials, and the materials after air is completely discharged are continuously heated for 3-5 min in a feeding cylinder under the condition of 131-139 ᵒ C, so that polybutene-1 near-melting-point melt is obtained;
when the isotactic polybutene-1 melt is supercooled melt, the heat treatment specifically comprises the following steps: adding the isotactic polybutene-1 granules into a feeding cylinder of a melt index instrument, and preheating for 2-3 min under the condition of 180 ᵒ ℃; after preheating is finished, weights are placed at the top end of a material rod of the melt index instrument to apply load, so that the material rod of the melt index instrument gradually moves downwards to discharge air among isotactic polybutene-1 materials, and the materials after the air is completely discharged are continuously heated for 3-5 min in a feeding cylinder under the condition of 180 ᵒ ℃; and after heating, cooling to 131-139 ᵒ ℃, and preserving heat for 8-10 min at the temperature to obtain the isotactic polybutene-1 supercooled structure melt.
2. The process of claim 1 for accelerating the transformation of form ii to form i by applying flow shear to a melt of isotactic polybutene-1 structure, wherein: the shear stress during flow shearing is 45-90 KPa.
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| CN110903493B (en) * | 2018-09-17 | 2022-08-02 | 天津大学 | Method for regulating and controlling transformation of crystal form II-crystal form I by adding liquid additive capable of matching with melt processing process of isotactic poly-1-butene |
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