MXPA97001845A - Mixed nanometric bodies of stratified silicate-ep - Google Patents

Abstract

An epoxy-silicate nanometer mixed body is prepared by dispersing an organically modified smectite clay in an epoxy resin together with diglycidyl ether bi-phenol-A (DGEBA), and curing in the presence of nadiomethyl anhydride (NMA), and / or benzyldimethylamine (BDMA), and / or boron trifluoride-monoethanolamine (BTFA) at 100-200 ° C, the molecular dispersion of the silicate stratified within the entangled epoxy matrix is obtained, with smectite layer separations of 100 A or more, and good wetting of the silicate surface by the epoxy matrix, the reaction includes the functional groups of the alkylammonium ions located in the galleries of the organically modified clay, which participates in the interlacing reaction and results in direct union of the polymer network to the molecularly dispersed silicate layers, the mixtonanomeric body exhibits an enlarged Tg at a slightly higher temperature than the unmodified epoxy; dynamic storage module nanometer mixed body is considerably higher in the glassy region and very superior in the rubbery plateau region when purchased with this module on epoxy unchanged

Description

MIXED NANOMETRIC BODIES OF STRATIFIED SILICATE-EPOXY FIELD OF LP > INVENTION This invention relates generally to mixed mineral-polymer materials, and very specifically to epoxy-srnectite nano-epoxy bodies and to a method for preparing the same.

BACKGROUND OF THE INVENTION Particulate minerals such as kaolin, talc, calcium carbonate, calcium sulfate and various micas have long been used as ex or inert fillers or fillers in similar polymers or matrices. Besides providing economic advantages in the extension of the expensive poly-material material, said fillers serve in many cases to improve the properties of the resulting plastics with respect to said parameters as coefficients of thermal expansion, rigidity and resistance to deformation. n. It is also well known in the art to make fillers of the above type gain increased compatibility with the polymer matrix to improve the interfacial adhesion of the mineral to the matrix. Therefore, for example, in Pápalos. , patent of E.U.A. No. 3,227,675, clay clays are described, whose surfaces are modified with organophonic silanes. The kaolin clays such as these are known as fillers for natural and synthetic rubbers and the like. Additional references of that type include Ianmcelli, patents of E.U.A. Nos. 3,290,165 and 3,567,680. Similarly, in the patent of F.U.A. No. 4,709,403, there will be described a method for producing a statified lattice silicate which is modified on its surface with an organic material. Staticized lattice silicate is contacted with an organic monomer, comonomers or a prepolymer, and surface polymerization or surface reaction is carried out. in the presence of a gaseous hydrogen atmosphere. Among the organic inonomers that can be used in the process are several nylon precursors. Very recently, procedures have been described which are said to be useful in the production of mixed materials composed of a polymer and a srnectite-type clay mineral, where the mineral is connected to the ionol by ionic bond. For example, in Kawas? Rní et al., Patent of E.U.A. No. 4,81,734 will describe a process in which a srnectite-type clay mineral is contacted with a swelling agent in the presence of a dispersion medium thus forming a complex. The complex containing the dispersion medium is mixed with monomer, and the donor is then polyrnephed. The patent states that the broaching agent acts to extend the distance between layers of the clay mineral, thus allowing the clay mineral to flow towards the interlayer space. The binding agent is a compound having a ring ion and a functional Lon capable of reacting and binding with a polymer compound. Among the polymers which can be used are polamide reams, vimlo polymers, thermosettable reams, polyester resins, polyamide resins and the like. In the patents of E.U.A. Nos. 4,739,007 and 4,889,885 are related descriptions. The swelling agents used in Kara umí et al, and related patents cited above, are technically qualified as or organoclays. In the present invention, the smectite-type organically modified clays hereinafter referred to as "organophilics" or "organoclays" are used as the mineral component of the mixed material. In general, the organoclays represent the reaction product of a clay of the ectite type with an ammonium compound containing higher alkyl (often a quaternary compound), and it has long been known to be used for the gelation of liquids. organic compounds such as lubricating oils, linseed oil, toluene and the like or for use as rheological additives in a variety of systems and liquid solvents based on organic compounds. The general procedures and chemical reactions according to which these organoclays are prepared are well known. Thus, under appropriate conditions the organic compound containing a cation will react by exchange of ions with clays containing a negative layer lattice and interchangeable cations to form the organoclay products. If the organic cation contains at least one alk group which contains at least 10 carbon atoms then the resulting organoclays will have the property of swelling in certain organic liquids. Among the patents of the prior art which broadly describe the aspects of the preparation and properties of organoclays are the patents of E.U.A. Nos. 2,531,427, 2,966,506, 3,974,125, 3,537,994 and 4,081,496. As used herein, the term "smectite" or "ectite type clays" refers to the general class of clay minerals with expandable glass lattices, with the exception of vermicellite. These include dioctilized smectites that consist of rnontmorillomta, beidellite and nontro ita, and trioctahedral methods, which include saponite, hectopta and sauconite. They also comprise synthetically prepared clays, e.g. by hydrothermal processes as described in the U.S.A. Nos. 3,252,757; 3,586,468; 3,666,407; 3,671,190; 3,844,978; 3.84-4.979; 3,852,405; and 3,855,147. The phase dispersions shown by the mixed materials hitherto described are relatively thick, and differ materially in this respect from the mixed nanometer bodies. The latter are a relatively new class of materials that show ultrafamous phase dimensions, typically on the 1-100 nm scale. Experimental work on these materials has generally shown that almost all types and classes of nanomaterial mixed bodies lead to new and improved properties when compared with their counterparts microscopic and macroscopic mixed bodies. Although the number of nanometric composite bodies based on srnectite-type clay and linear thermoplastics is increasing, little work has been devoted to interlaced polymer systems such as epoxy. Recent reports of mixed particle-based epoxy materials suggest that dimensional stability, conductivity, mechanical properties, thermal properties and other properties can be modified due to the incorporation of filler particles within the epoxy material. However, for most, the improvements in the properties observed with these conventionally prepared mixed bodies are moderate when compared (over a base of equal volume of particulate filler) to those that have been established for several mixed nanornetric bodies of polymer-ceramic. The previous work carried out by the inventors on polyamide and poly-caprolactone have demonstrated the feasibility of dispersing molecular silicate layers within an inacromolecular matrix, which results in significant improvements in physical properties only with moderate particle contents ( < 10% by volume). lang and Pinnavaia have recently reported the release of organically modified smectite in an epoxy resin by heating an exchange form with montrnorillonite onium ion with epoxy resin at room temperature. 200 ~ 300 ° C. Chemistry of Materials, vol. 6, pages 468-474 (April, 1994). X-ray and electron microscopy studies of the mixed body suggest the de-laination of the silicate layers, although the phase segregation of the smecticite coated with polyether of the epoxy material was observed. In addition, the product of the high temperature cure reaction is an untreatable powder instead of a continuous solid epoxy matrix. According to the foregoing, an object of the invention can be considered to provide a mixed nanosized smectite-epoxy body that can be mixed, applied in various forms (e.g., as adhesive films, coatings or castings) and cured by conventional means. A further object of the invention is to synthesize a nano-polymeric-ceramic composite body in which the individual layers of smectite-type clay bodies with a thickness of 10A and a high aspect ratio (100-1000) are dispersed within a Epoxy matrix intertwined. A further object of the invention is to provide a process for the preparation of a mixed rnormometric body of ectite-epoxy which meets the above requirements, and is processed using conventional epoxy curing agents at significantly lower temperatures than previously used. Still another object of the invention is to provide a method for preparing a mixed smectite-epoxy body, in which the resulting mixed body shows molecular dispersion of the silicate layers in the epoxy matrix, good optical clarity and dynamic mechanical properties. significantly improved compared to the unmodified epoxy.

BRIEF DESCRIPTION OF THE INVENTION Now, according to the present invention, there is provided a method for preparing a mixed rnanornetric epoxy-clay body of the ectite type, according to which a smectite-type clay dispersed in a epoxy resin has been dispersed. been modified to an organoarcilla by an exchange of ions with a salt of alq? lamomo, together with diglycidyl ether of bisphenol A (DGEBA). The positive ion of the salt is of the general form + NH3R1, + NH2R2R3 / + NHR4R5R6 or + NR7R8R9RIO, where Ri to Rio are organic radicals; and where Ri, at least one of 2 and R3, at least one of R «, Rs, and Ré, and at least one of R7, Re, and RIO, contain a functional group capable of reacting and binding to the epoxy under entanglement thereof, such as hydroxy or epoxy, or carboxylic. Preferably an ammonium salt having at least one alkynyl onium chain having a terminal hydroxyl group is used. A particularly preferred ammonium salt comprises a bis (2-hydroxyethi) rnetiisebo-alkylamino salt. The mixture is cured in the presence of a curing agent which is entangled with DGEBA in the presence of an organoclay, reacts directly with the organoclay or catalyzes the entanglement reaction between the organoclay and DGEBA. This allows the dispersion of the organoclay in the dry state, and allows the healing of the nanometric mixed body to occur at much lower temperatures than in the prior art. In addition, the formation of chemical bonds between the interlaced network and the nanoscale silicate particles result in a direct attachment of the epoxy matrix to the silicate layers, thus maximizing the adhesion between the two phases. The cure is typically carried out at temperatures in the range of 100 to 200 ° C. The most preferable smectite to be used in the invention is montmorillonite, which structure consists of cap > ace made of an octahedral alumina sheet sandwiched between two sheets of tetrahedral silica. The curing agent can be selected from one or more members of the group consisting of nadicmethyl anhydride (MNA), benzyldirnethylamine (BDMA), and boro-onoethumethyl fluoride (BTFA).

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings appended hereto: Figure 1 illustrates XRD diffraction patterns of a dry organoclay powder and the uncured organoarcil mixture / DGF.BA. Figure 2 illustrates XRD pads of an organoclay / DGFBA mixture (4% by volume of MTS) heated in situ at various temperatures. The spectra are displaced vertically for greater clarity at scrutinizing temperatures (in ° C) from lower to higher as follows:; fifty; 70; 90; 100; 110; 120; 130; 140; 150. Dashed lines indicate the site of silicate reflections (001) and (002) at 20ßC. Figure 3 is an XRD pattern of a mixed organo-clay body DGEBA / MDA containing 2% by volume of 2% OMTS. The silicate reflection (001) corresponds to a layer separation of 36A. Figure 4 illustrates XRD patterns of an organoarcilla / DGEBA / BDMA (4% by volume organoarclia) mixture heated in situ. at various temperatures. The spectra move vertically for clarity, with scrutinizing temperatures (in ° C) from lower to higher as follows: 20; fifty; 70; 90; 100; 110; 120; 130; 150. The discontinuous lines indicate the location of the silicate reflections (001) and (002) at 20 ° C. in Figures 5 and 6 respectively illustrate XRD patterns of mixed bodies of cured organoclay nanometer / DGEBA / BDMA and organoclay / DGEBA / NMA which contain A: 0. 4% B: l.2% C: 2% D: 4% by volume of organoarcylate. The spectra move vertically for clarity. Figure 7 shows TEM icrographs of thin sections of fully cured organoarcilla nanométpcos mixed bodies / DGEBA / NMA containing 4% by volume of MTS. The scattered silicate layers are seen from the edge and are clearly visible as dark lines of approximately IDA thickness, with 80-120A of epoxy matrix separating the immediate silicate layers. Scale bars = a) lOOnrn and b) lOnm. Figure 8 illustrates FT-IR spectra of a) DGEBA / BDMA and B) organoarcilla / DGEBA / BDMA (4% by volume of MTS) beef mixtures taken at various temperatures during in situ heating at 0.5 ° C / rn ? n Figure 9 illustrates curing scans of organarcilla DSC / DGEBA / BDMA (dotted line) and DGEBA / BDMA (solid line). Figure 10 shows curing runs of organoclay DSC / DGEBA / NMA (dotted line) and DGEBA / NMA (solid line); and Figure 11 illustrates the temperature dependence of E '(open symbols) and tan & (shaded symbols) for DGEBA / BDMA completely cured and organoarcilla / DGBA / BDMA containing 4% by volume of MTS.

DESCRIPTION OF THE PREFERRED MODALITIES The synthesis procedure used for the preparation of a mixed nanometric body includes the dispersion of the organoclay in a suitable monomer, followed by the polymerization. Under appropriate conditions, the dismemberment of the organoclay in cap > individual silicate heads, which eventually disperse within the macro olecular matrix. In a typical procedure, the mixing of the organoclay and DGEBA is carried out at temperatures in the range of 20 to 150 ° C, followed by sonication, the addition of a curing agent and the healing of the network at a scale of prescribed temperatures. The initial mixing of the organoclay and DGEBA is most preferably carried out at about 90 ° C to ensure low resin viscosity. After the addition of small amounts of the clay (0.1 to 10% by weight), the resin viscosity is only slightly increased. However, briefly sonicated samples (1-2 minutes) undergo significant increase in ream viscosity at relatively low shear rates changing from opaque to semitransparent during sonication. Organo-clay loads of about 10% (w / w) begin to result in strong gel formation during sonication, even after reheating at temperatures of, or above 100 ° C. The observed increase in resin viscosity after sonication may be due to the dispersion of silicate layers of high aspect ratio (100-1000) within the epoxy resin and is due to the formation of a so-called "castle" structure of cards ", in which the interactions from edge to edge and edge to face between the scattered layers form precooling structures. Similar rheological changes have been observed when organoclays are dispersed in various organic media and are attributed to the formation of the "card cast" structure. The invention is further illustrated by means of the following example, which should be considered as illustrative and not as limiting the invention of another described form: EXAMPLE Synthesis of nanometric mixed body samples The organoclay used in this example is prepared by Southern Clay Products, Inc., of Gonzales, Texas by an ion exchange reaction of Na-montmopllonite and bi (2-hydroxyethyl) methyl-sulfoalkylarylonium chlorur-o. (Ethoquad T / 12, Akzo Chemicals) as shown in equation 1: Na + -mectitol + (HOCH2CH2) 2R'R "N + C1 (HOCH2CH2) 2R'R" N + - eemectit.a «• NaCl (1) in where R 'is predominantly an octadecyl chain with smaller categories of lower homologs (approximate composition: Cía 70%, Cie 25% and CIA 4% and C12 1%) and R "is a methyl group The dried organoclay powder was added with stirring to diglycidyl ether of bisphenol A (DGFBA, DER 332 from Dow Chemical, epoxide equivalent weight = 178) and cured by the addition of either nadic ethylic anhydride (NMA, Aldrich), tp boron-rnononoethanolarnine lutein (BTFA, Aldrich), benzyldinethylamine (BDMA, Aldrich), or ethylenedianilma (MDA, Aldrich). The curing agent used for each formulation was as follows: DGEBA / NMA: 87.5 parts NMA per hundred resin (phr), with or without 1.5 phr BDMA DGEBA / BDMA: 1.5-10 phr BDMA DGEBA / BTFA : 3 phr BTFA, DGEBA / MDA: 27 phr MDA, Organoarcilla / DGEBA mixtures were maintained at 90 ° C with shaking for one hour, then they were dunked for 1-2 minutes still hot using a Fisher 300 model sonic disrupter (Fisher Scientific , Itasca, ID Afterwards, the somatic samples were cooled, and the curing agent was added with a complete mixing; and then loaded into disposable syringes. The samples were rinsed in the syringes for 30 seconds at 3000 rpm to remove bubbles, and then discarded in rectangular Teflon molds with dimensions of 20 nm by 10 nm by 1.5 thickness, or cast as free-form films with thickness of 0.1-0.3 rnm. All samples were cured at 100 ° C for 4 hours, 150 ° C for 16 hours and 00 ° C for 12 hours (vacuum).

C acterization of the nano-sized mixed body X-ray diffraction experiments (XRD) were carried out directly on samples of rich nanomet mixed bodies using a diffractornet Scmtag Pad X with Cu (= 1.54A) or Cr (= 2.29) radiation. fl). In situ, the XRD experiments in hot stage were conducted using a special thermal fixation that allowed the samples to be heated to a number of different temperatures without removing the sample from the li. The samples were agitated at 10 ° C / m between the set of temperatures and scrutinized after an isothermal equilibration of 10 minutes. The exothermic curing reaction of the epoxy was followed by differential scanning calorimetry (DSC) using a Pont 9900 thermal analyzer. The spectra were obtained by flowing nitrogen at a scanning speed of 10 ° C / mm. Mfrarojos in situ cure studies were carried out in a Mattson Galaxy 2020 FT-IR Series using a variable temperature programmable heating cell (Model HT-32, Spectra-Tech, Inc). The spectra were collected at a resolution of 4 cmi. An image of a mixed-body microscope was formed using transmission electron microscopy (TEM) in carbon coated sections of the mixed race using a JEOL 120DEX transmission electron microscope at an acceleration voltage of 120 kV. The dynamic mechanical analysis (DMA) of the cured mixed body films was carried out on a Rheovibron DDV-TI-C viscometer (Toyo Baldwin Co., Japan) operating at a 110 Hz drive frequency and at a scanning speed at a temperature of 1 ° C / m? n.

Organoclay dislocation XRD analysis was used to track the progress of organoclay dispersion during mixing with DGEBA and subsequent healing reactions. Figure 1 shows the XRD patterns of the dried organoclay and the uncured organellar / DGEBA mixture. The top scrutiny was obtained at room temperature following heating of the organoclay / DGEBA mixture at 90 ° C for one hour. The XRD pattern of the organoclay powder shows a primary silicate reflection (001) at 2 = 4.8 °, with a low intensity projection at approximately 2 = 5.8 °. The main reflection of silicate in organoclay corresponds to a d-spaced layer of 17 ° which represents an increase of approximately 7fi of the van der Uaals space of Naontmop 11onit. After mixing the organoclay and the DGEBA at room temperature, an additional reflection arises centered at 2 -2.5 ° corresponding to organoarcilla / DGEBA intercalated. As is known, organoclays can easily intercalate several small organic molecules, either from the vapor or liquid phase. The second peak at 2 -5o corresponds to the coexistence of organoarcilla (d (ooi) = 17ñ) not interleaved and (d (002) = 17.5ñ) interspersed. The persistence of a certain organoclay not intercalated at room temperature can also be observed by the small remaining projection at 2 = 5.8 °. In contrast, the mixture of the DGEBA and the organoarcilla at 90 ° C results in only organoarcilla interspersed with DGEBA (d (ooi) = 35ñ) without peaks of residual organoclay, as shown in the upper trace of Figure 1. The reflections observed at 2 = 2.5 °, 4.9 ° and 7.6 ° correspond to the reflections (001), (002) and (003) of the interleaved phase of the DGEBA, respectively. Additional evidence for the presence of only interspersed organoarcilla / DGEBA comes from the disappearance of the organoarcilla projection at 2 = 5.8 °, which is no longer masked by any of the silicate reflections (001). The XRD results described relate to resin samples cooled to room temperature after mixing at 90 ° C and, therefore, do not necessarily represent the structures present at the mixing and curing temperatures. XRD experiments in situ high dynamic temperature, were used to determine the exact structure of resin blends at elevated temperatures. The samples were prepared by mixing organoarcillas and DGEBA in a flask at 90 ° C, and cooling to room temperature before transferring them to a fractometer chamber. In Figure 2 a series of XRD screeners of the organo-clay / DGEBA mixture previously heated at 90 ° C are shown at various intervals between room temperature and 150 ° C. The scudpñacionee at ba temperature exhibit three orders of reflections that indicate the existence of reflections that indicate the existence of organoarcilla intercalada DGEBA with (d (ooi) = 36fi). By increasing the temperature a gradual increase in d (ooi) from 36 a to about 38, was observed, although the constant intensity of the peaks suggests that there is n y and little or no deslanmation at or below 150 ° C. With the observation that the intercalation, but not the disappearance of the organoclay occurs in the presence of the DGEBA, the inventors sought to identify the potential epoxy curing agents, which would produce both the organo-clay flaking and the entanglement of the epoxy ream. . It was found that the choice of the curing agent was critical to determine the delamination and optical clarity.

Selection of the curing agent A study of common epoxy curing agents revealed that many curing agents studied resulted in little or no increase in layer separation, resulting in mixed bodies with separated-silicate d of 30-40 or less . An example of this behavior is shown in Figure 3 for a mixed organoarcilla / DGEBA body cured with methylene diamine (MDA). This mixed body was prepared by adding MDA to the organo-clay / DGEBA mixture, which resulted in an immediate turbidity of the resin. Interestingly, it was found that all of the bifunctional primary and secondary amine curing agents used had this effect and resulted in opaque mixed bodies, in contrast to the transparent mixed bodies subsequent to the delamination of the organoclay. An explanation for this behavior could be the bridging of the silicate layers by the bifunctional amine molecules, which prevents further expansion of the layers. Another possibility is that the N-H groups in the primary and secondary amines are sufficiently polar to cause the disintegration of the dispersed silicate layers. Others have observed the similar degelification (de-exfoliation) of organoclays dispersed in organic solvents with the addition of polar additives. In accordance with the present invention, curing agents (NMA, BDMA, BTFA and combinations thereof) have now been discovered which result in the delamination of the organoclay during the heating of the reflection mixture. Figure 4 shows XRD ín sit? of the organoarcilla / DGEBA / BDMA mixture illustrating the delarnmado of La organoarcilla by heating from room temperature to 150 ° C. As before, the mixture was prepared by mixing the organoclay and the DGEBA in a bottle at < 30oC, cooling to room temperature and mixing in BDMA just before transferring them to the diaphragm chamber. Mixing the BDMA in the organoarcilla resin / DGEBA at room temperature resulted in a system interspersed with d (ooi) = 39ñ (slightly expanded from d < ooi) = 39fi observed with the organoclay / DGEBA). Moreover, in contrast to what is observed in the absence of a curing agent, the heating of the organoarcilla / DGEBA / BDMA mixture resulted in a substantial attenuation of the peak at 2 = 2.3 °. The peak almost disappeared by 150 ° C (upper part of figure 4), remaining only one trace at 2 = 3 °. The virtual disappearance of the reflections of organoarciila (001) clearly indicates that the dismemberment of the organoarcilla has taken place. XRD analyzes of completely cured nanoinetic mixed body samples also lacked silicate r-efflections (001) as shown in Figures 5 and 6 for organoarcilla / DGEBA / BDMA and organoarcilla / DGEBA / -NMA, respectively. The absence of silicate reflections (003) in the mixed nanometric bodies shows that the delamination and dispersion of the silicate layers within the epoxy matrix is retained after the complete cure of the epoxy. The silicate exfoliation was additionally confirmed using TEM. The micrographs of the mixed body cured with BDMA are shown in figure 7. These micrographs show very clearly the existence of individual scattered silicate layers (dark lines in figure 7) of a thickness of lnm stratified in the epoxy matrix. Some areas of the epoxy matrix contain oriented collections of 5-10 parallel silicate layers. These domains of parallel layers are presumably remnants of organo-clay touches, but with the substantial expansion of the galena beyond that corresponding to an interspersed silicate phase (see for example figures L and 3). A closed examination of these domains reveals consistent layer spacings of approximately 100R or more, with the galenas intervening between layers filled with interlaced epoxy matrix. It is particularly interesting to note that the samples are mostly homogeneous without any phase separation between the silicate layers and the epoxy mat. In fact, the examination of the micrographs shows an excellent apposition between the clay layers and the polimépca matrix.

Healing reactions In contrast to the work of U ng and Pmnavaia, where no curing agent was added, a curing agent is used in the present invention which either intertwines DGFBA in the presence of organoarc 1 la, reacts directly with the organoarcilla, or catalyzes the interlacing reaction in the organoarcilla and the DGEBA. The benefits of this scope are, first, that the healing of the mixed nanometric body occurs at much lower temperatures than those previously reported, and second, that the formation of chemical bonds between the interlaced network and the nanometric particles of silicate results in direct fixation of the epoxy matrix to the silicate layers, thus maximizing inter-facial adhesion between the two phases. A preferred curing agent is BOMA, which can catalyze the DPOBA oven, but is also capable of catalyzing the reaction between hydroxyl groups of the organoalkyl ions of organocarbon and the oxirane rings of DGEBA. The healing conditions of the mixed ream can have an effect on the reaction mechanism. For example, increasing the temperature of the organoarcilla / DGEBA / BDMA and DGEBA / BDMA mixtures from 20 ° C to 250 ° C at low speeds (0.5 ° C / rnm) results in little difference in the healing behavior between the mixed body and the unmodified epoxy as shown by comparison of the corresponding infrared spectra (Figure 8). Both series of spectra show gradual disappearance of the epoxy band at 918 crn-i at temperatures between 80 ° C and 15 ° C. The extent of the DGEBA reaction given by the intensity of the epoxy peak is approximately equivalent for both compositions (organoclay / DHEBA / BDMA and DGEBA / BDMA). At higher heating rates, however, a difference in healing behavior is observed. Figure 9 shows DSC scans of the organo-clay / DGEBA / BDMA and DGEBA / BDMA curing reactions at a scanning rate of 10 ° C / nmr, showing a strong exotherm associated with curing between 100 and 150 ° C for organoarcilla / DGEBA / BDMA. The fact that the DSC scrutiny of the DGEBA / BDMA mixture shows an exotherm 7 2 considerably smaller on the same temperature scale, suggests that the organoarcilla plays a catalytic role in the base-catalyzed homopolynenation of DGEBA, or that the reaction proceeds by means of a totally different mechanism in the presence of the organoarcília. One possibility, as < e shows in equation 2, includes the opening reaction of the base-catalyzed oxirane ring between hydroxyl groups of organoarcilla and DGEBA which results in the formation of I, an organoarcilla-glycidyl ether of oligo ero A Bisphenol Compound I can subsequently react with free DGEBA by a similar base catalyzed oxirane ring opening to build the entangled epoxy network. It is interesting to note that the temperature at which the cure occurs (approximately 100 ° C as shown with the exotherm in Figure 9) corresponds to the same temperature at which the delamination of the organoclay occurs (see Figure 4). . The coincidence of curing and delamination temperature makes intuitive sense, since the delammation exposes the hydroxyl groups of the chains of acyl ammonium in the interlayer to DGEBA and BDMA. The par icipation of the alkylammonium ion of hydroxyl organo-clay in the curing reaction is illustrated more clearly with the organoar cyl system / DGEBA / NMA. Interestingly, complete healing of the DGEBA / NMA mixture does not occur in the absence of the oragano-clay, regardless of the rate of heating. Figure 10 shows DSC scans of the organo-clay / DGEBA / NMA healing reaction. During the dynamic healing of this formulation two different exotherms were observed; a weak one at 180 ° C followed by a strong exotherm at 247 ° C. Although the complete sequence of reactions has not yet been determined, a possible sequence could first include the reaction of organo-clay hydroxyl groups with NMA to form the monoester, II, as shown in equation 3.

NMA II (3) The nascent carboxylic groups of TI can subsequently react with the epoxide resulting in the formation of the diester, III, according to equation 4.

III (4) The subsequent reaction of III with DGEBA results in the formation of epoxy network. This reaction sequence results in a chemical bond between the organoclay and the epoxy network. It is clear from the data shown in Figure 10 that in the absence of the organoclay, the DGEBA / NMA formulation does not result in cure under the conditions used in this experiment. This provides additional evidence that the organic component of the organoclay participates in the healing reaction.

MECHANICAL PROPERTIES OF MIXED BODIES NFlNOMETRICOS The effect of molecular dispersion of the silicate layers on the viscoelastic properties of the entangled polymer matrix was tested using DMA. This experiment includes the application of an oscillating deformation to a sample while following the resulting effort, which consists of both cornpenent.es, in phase and out of phase. Then these efforts can be used to calculate the components of the module in phase (E ') and out of phase (E "). The ratio E" / E' = tan 6 is a measure of the ratio of loss of energy to energy stored by deformation cycle, and typically goes through a maximum to glass transition (T9) of the polymer. At Tβ there is a substantial drop in E, with a peak at 6 o'clock indicating viscous damping due to segmental movement in the polymer. For interlaced polymers, both E "and T9, generally increase with the interlacing density, Figure 11 shows the temperature dependencies of the voltage storage module, E 'and tan or of the mixed body of organoarcilla / DGEBA / BDMA. It contains 4% silicate by volume, and the epoxy DGEBA / BDMA without any silicate.The deviation and amplification of the peak 6 at higher temperatures indicates an increase in T9 of the mixed nano-ethic body and expansion of the glass transition. deviation in T9 measured by the maximum peak so 6 is in the order of only a few degrees (4 ° C for the sample shown in Figure 11) and can not explain the significant increase in flat-plane modulus. The extent of healing is comparable in both samples (measured by DSC), the increase can not be attributed to variations in cure.The increase and increase of T9 have been observed in other mixed nanornetric bodies or Inorganic-organic organisms are generally attributed to restricted segmental movements near the orgamca-morganica mechanism. Chemical bonding in the silicate and epoxy matrix terphase could lead to impaired relaxation mobility in the polymer segments near the interface, which leads to the enlargement and increase of T9. Below T9, both samples exhibit high storage modulus, with a slight decrease in E 'with increasing temperature. Notably, E 'in the vitreous region below T9 is approximately 58% higher in the mixed nanometpco body compared to pure epoxy (2.44 x L0 * o compared to 1.55 x 10 * 0 dmas / cm2 at 40 ° C). Even more surprising is the large increase in E 'in the planarized flat region of the mixed nanometric body as shown in Figure 11. The mixed nanomaterial body exhibits a flat region modulus approximately 4.5 times greater than the modified epoxide (5.0 X). 102 compared to ll X 102 dynes / crn at 150 ° C). These changes are considerable, particularly in view of the fact that the silicate content is only 4% by volume. In this context, it is interesting to compare these results with reports of viscoelastic properties of conventionally prepared epoxy mixed bodies containing filler particles of micron size or larger. Typically, conventional filled epoxies do not exhibit substantial changes in E 'to the volume contents of the filler (<10%), used in this study. The theoretical expressions have been derived by Halpin and Tsai (Halpin, J. C, Kardos, J.L Polyrn, Eng. Sci 1976, 16, 344) p > to calculate elastic modulus of a mixed body consisting of uniaxially oriented particles of filling suspended in a continuous matrix. For mixed bodies with plate-like particles, these equations predict a strong dependence of mixed-body elastic modulus in the ratio between grid dimensions of the filler. Solving the simultaneous Halpin-Tsa equations, with data from the experimental dynamic storage module in the vitreous region and the rubber-like region, produces a relation between apparent grid dimensions of 43. From the TEM micrographs shown in figure 7 it is clear that part of the relatively unmodified epoxy matrix exists between the 5-10 layers of silicate layers. As a result, the ratio of effective grid dimensions of the silicate-rich domain could be much lower than 100-1000 predicted for fully delaminated and dispersed silicate layers. Although the present invention has been set forth particularly in terms of specific embodiments thereof, it will be understood, in view of the present disclosure, that numerous variations in the invention now qualify those skilled in the art, the variations of which still reside within the scope of the invention. scope of the present teachings. Therefore, the invention is broadly constructed, and limited only by the scope and spirit of the appended claims.

Claims (16)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for preparing a nano-composite epoxy-clay smectite-type mixed body, which comprises dispersing in an epoxy ream a dry smectite-like clay which has been modified to an organoclay by ion exchange with an alkali metal salt, together with diglycidyl ether or bisphenol A (DGEBA); the salt ion of the salt is from the formula + NH3R1, + NH2R2R3, + NHR.? RsR6, or + NR7R8R9R10, where Ri to Rio are organic radicals; and where Ri, at least one of R2 and R3, at least one of R4, R5 and Re and at least one of R? , Re, R9 and Rio / contain a functional group capable of reacting and binding with the epoxy by interlacing the same; and curing in the presence of a curing agent which, intertwines with DGEBA in the presence of said organoarcília, reacts directly with the organoclay, or catalyzes the entanglement reaction between the organoclay and DGEBA.

2. A method according to claim 1, further characterized in that said functional group is selected from one or more members of the group q? E consists of hydroxyl, epoxy or carboxylic groups.

3. A method according to claim 1, further characterized in that said ammonium salt has at least one alkylamine chain having a terminal hydroxyl group.

4. A method according to claim 1, further characterized in that said ammonium salt comprises a salt of bis (2-hydroxyethyl) metherssealkylmonium.

5. A method according to claim 1, further characterized in that said curing agent is selected from one or more members of the group consisting of nadicmethyl anhydride (NMA), benzyldimethylamine (BDMA), and boron trifluoromethanolamine. (BTFA).

6. A method according to claim 1, further characterized in that said smectite-type clay comprises a montorylomata.

7. A method according to claim 1, further characterized in that the curing agent is capable of catalyzing the homopolynection of DGEBA and catalyzing the reaction between said terminal hydroxyl group of organoclay and the oxirane rings of said DGEBA.

8. A method according to claim P, further characterized in that said curing agent comprises BDMA.

9. A method according to claim 5, further characterized in that said quaternary ammonium salt comprises a salt of bie (2 ~ h? Drox? Et? L) methylseboalklammonium.

10. A method according to claim 5, further characterized in that said curing is carried out at temperatures in the range of 100 to 200 ° c.

11. - A method in accordance with the claim 5, further characterized in that the dispersion of the dry srnectite in the epoxy resin is carried out by mixing the srnectite and DGEMA at temperatures in the range of 20 ° to 150 ° C, followed by sonication.

12. A mixed nanorubber body of pelifero-mineral comprising an organic-modified smectite clay that is dispersed molecularly within an interlaced and continuous solid epoxy matrix.

13. A mixed nano-ethnic body according to claim 12, further characterized in that the phase dimensions are in the scale of 1-100 nm; and the nanometric particles of ectite are chemically bound to the interlaced network.

14. A nano etpco mixed body according to claim 12, further characterized in that the smectite has a layer separation of at least 100 fi.

15. A mixed nanometer body according to claim 12, further characterized in that the smectite-type clay has been modified by ion exchange with an alkylammonium salt having at least one alkylammonium chain with a terminal hydroxyl group.

16. A mixed body nanometpco according to claim 15, further characterized in that said quaternary ammonium salt comprises a salt of b? S (2-hydroxyethyl) me? Lseboalqu? Lamon? O.