Morphology and mechanical properties of dual‐curable epoxyacrylate hybrid composites

A dual‐curable epoxyacrylate (EA) oligomer with one epoxide group and one vinyl group at each end was synthesized for the application as adhesive sealant in the liquid crystal display panels. However, after UV and thermal cure, the EA resin was brittle with a poor resistance to crack initiation and propagation. Liquid rubbers with different functional end groups were thus tried as toughening agents for the EA resin. Among all the rubber‐toughened EAs, the EA‐V5A5 added with vinyl‐terminated and amino‐terminated butadiene‐acrylonitrile copolymers (VTBN and ATBN) each at 5 phr had the highest fracture toughness, tensile strength, and elongation at break but a lower initial modulus. To raise the modulus, submicron‐sized silica particles (∼170 nm) with surface vinyl functional groups were further added to the EA‐V5A5 to prepare the hybrid composites. Because of interfacial chemical bonding provided by the surface vinyl functional groups, both modulus and fracture toughness were increased by adding silica particles, without any appreciable decrease in extensibility. For the hybrid composite at 20 phr silica particles, the initial modulus, fracture toughness, and fracture energy were raised by 10.3, 100, and 267%, respectively, when compared to the neat epoxyacrylate. Owing to their strong interfacial bonding, the increase of fracture toughness was mainly due to the crack deflection and bifurcation on silica particles, in addition to the rubber particle bridging and tearing as evidenced by SEM pictures on the fracture surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41820.     

Mode‐I intralaminar fracture toughness of silica particles‐filled glass woven fabric‐reinforced vinyl ester composites

Glass woven fabric reinforced vinyl ester (GV) composites filled with different weight proportions of silica particles were fabricated by hand lay up technique followed by oven curing. The plane strain Mode‐I Intralaminar fracture toughness, K_IC of the silica filled GV composites has been studied and the experimental results were compared with those of unfilled GV composites. The findings of the experiments showed that the fracture toughness has improved by the addition of silica particles up to 6 weight % with marginal increase of tensile properties. The silica filled and unfilled GV composites showed brittle fracture, with maximum toughness for 6 weight % silica particles. The morphology of fracture surfaces was examined by using SEM. Pulled and fractured fibers are observed on the fracture surface of GV composites evidencing fiber bridging but not in the silica filled GV composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Mechanical properties of high density packed silica/poly(vinyl chloride) composites

This article focuses on the preparation and mechanical properties of silica/poly(vinyl chloride) (PVC) composites enriched with 60% mass ratio of 130 nm and 30 nm silica sphere fillers. Silica particles were pre‐treated with silane, IO₇ T₇(OH)₃ (trisilanol isooctyl polyhedral‐oligomeric silsesquioxane) to prevent agglomeration. The dispersion and interfacial compatibility of silica particles in a PVC matrix were investigated by scanning electron microscopy. The composite mechanical properties were characterized by tensile test, revealing improved Young modulus and tensile strength. Compared to pure PVC, the stiffness of 30 nm and 130 nm silica/PVC composites is on average increased by 30–40%, respectively. Similar trend was observed for the composite tensile strength on the change of the silica size. In contrast, elongation at break decreased for both composites compared to pure PVC, for 15% in 30 nm and for 30% in 130 nm silica/PVC composite. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Preparation and properties of an oxide fiber‐reinforced silica matrix composite

Oxide (Nextel? 440) fiber‐reinforced silica composites, with the density and porosity of 1.97 g/cm³ and 21.8%, were prepared through sol‐gel. Their average flexure strength, elastic modulus, shear strength, and fracture toughness at room temperature were 119.7 MPa, 25.6 GPa, 10.8 MPa, and 4.0 MPa·m^1/2, respectively. The composites showed typical toughened fracture behavior, and distinct pullout fibers were observed at the fracture surface. Their mechanical properties were performant up to 1000°C, with the maximum flexural strength of 132.2 MPa at 900°C. Moreover, the composites showed good thermal stability, even after thermal aging and thermal shock at elevated temperatures.     

Co‐poly(vinyl chloride‐vinyl acetate‐vinyl alcohol)‐silica nanocomposites from sol–gel process: Morphological,mechanical, and thermal investigations

Organic–inorganic nanocomposites consisting of co‐poly(vinyl chloride‐vinyl acetate‐vinyl alcohol) and silica were prepared via sol–gel process. Two types of hybrids were prepared, one in which interactions between hydroxyl group present in the copolymer chain and silanol groups of silica network were developed. In the second set, extensive chemical bonding between the phases was achieved through the reaction of hydroxyl groups on the copolymer chains with 3‐isocyanatopropyltriethoxysilane (ICTS). Hydrolysis and condensation of tetraethoxysilane and pendant ethoxy groups on the chain yielded inorganic network structure. Mechanical and thermal behaviors of the hybrid films were studied. Increase in Young's modulus, tensile strength, and toughness was observed up to 2.5 wt % silica content relative to the neat copolymer. The system in which ICTS was employed as binding agent, the tensile strength and toughness of hybrid films increased significantly as compared to the pure copolymer. Thermogravimetric analysis showed that these nanocomposite materials were stable up to 250°C. The glass transition temperature increases up to 2.5 wt % addition of silica in both the systems. Field emission scanning electron microscope results revealed uniform distribution of silica in the copolymer matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polypropylene/silica micro‐ and nanocomposites modified with poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)

The effects of different silica loadings and elastomeric content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with 5, 10, 15, and 20 vol % of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) SEBS added to total composite volume were investigated. Four silica fillers differing in size (nano‐ vs. micro‐) and in surface properties (untreated vs. treated) were chosen as fillers. Elastomer SEBS was added as impact modifier and compatibilizer at the same time. The morphology of ternary polymer composites revealed by light and scanning electron microscopies was compared with morphology predicted models based on interfacial properties. The results indicated that general morphology of composite systems was determined primarily by interfacial properties, whereas the spherulitic morphology of polypropylene matrix was a result of two competitive effects: nucleation effect of filler and solidification effect of elastomer. Tensile and impact strength properties were mainly influenced by combined competetive effects of stiff filler and tough SEBS elastomer. Spherulitic morphology of polypropylene matrix might affect some mechanical properties additionally. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41486.     

Fracture toughness of silica particulate‐filled epoxy composite

The relationship between the postcuring conditions and fracture toughness on three silica particulate‐filled epoxy composites was investigated. The glass transition temperature, T_g, and the fragility parameter, m, derived from the thermo‐viscoelasticity, were used to characterize the composites, which were postcured under various conditions. The glass transition temperature and fragility both depended on both of the curing conditions and the volume fraction of silica particles. The glass transition temperature increased with the postcuring time and temperature, while the fragility generally decreased as the volume fraction increased. There was no direct correlation between the glass transition temperature and fragility. The fracture toughness depended on both the glass transition temperature and fragility. The composites with a high glass transition temperature and low fragility had high fracture toughness. These results indicate that the glass transition temperature and fragility are useful parameters for estimating the fracture toughness of the silica particulate‐filled epoxy composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2261–2265, 2002     

The effect of the interface structure of different surface‐modified nano‐SiO2 on the mechanical properties of nylon 66 composites

The nylon 66‐based nanocomposites containing two different surface‐modified and unmodified SiO₂ nanoparticles were prepared by melt compounding. The interface structure formed in different composite system and their influences on material mechanical properties were investigated. The results indicated that the interfacial interactions differed between composite systems. The strong interfacial adhesion helped to increase tensile strength and elastic modulus of composites; whereas, the presence of modification layer in silica surface could enhance the toughness of composites, but the improvement of final material toughness was also correlated with the density of the adhered nylon 66 chains around silica nanoparticles. In addition, the results also indicated that the addition of surface‐modified silica nanoparticles has a distinct influence on the nonisothermal crystallization behavior of the nylon 66 matrix when compared with the unmodified silica nanoparticle. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A comparative study on the preparation and physical properties of environmental friendly PMMA‐silica nano/sub‐micron‐scale hybrid latexes controlled by chelating agent

In this article, a comparative study of the preparation and physical properties of as‐prepared PMMA‐silica nano‐hybrid (PSN) and sub‐micro‐hybrid (PSM) latexes is successfully presented. Vinyl‐modified silica spheres were prepared using the Stöber process with/without a chelating agent to control particle size. The as‐prepared vinyl‐modified silica spheres with different particle sizes were subsequently characterized by SEM, ¹³C‐solid‐state NMR, and ²⁹Si‐solid‐state NMR spectroscopy. A certain feeding amount of silica spheres was reacted with MMA monomers by emulsion polymerization to yield a series of PSN and corresponding PSM. Both as‐prepared nano/sub‐micronscale hybrid materials were further characterized by FTIR, SEM‐EDX mapping, and TEM studies. The comparative study on the physical properties of both as‐prepared nano/sub‐micron‐scale hybrid materials was done systematically based on a series of instrumentation evaluations performed using a dynamic mechanical analyzer, electrochemical corrosion measurements, salt spray test, and gas permeability analysis. Results indicated that PSN has more effectively enhanced mechanical properties, corrosion protection properties, as well as gas barrier compared to PSM. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Effect of a dodecylsulfate‐modified magnesium–aluminum layered double hydroxide on the morphology and fracture of polystyrene and poly(styrene‐co‐acrylonitrile) composites

Composites of polystyrene (PS) and poly(styrene‐co‐acrylonitrile) (SAN) containing a fraction of a dodecylsulfate‐modified Mg–Al layered double hydroxide (LDH) were prepared by means of a melt‐extrusion process. The structure and morphology were analyzed with wide‐angle X‐ray scattering and transmission electron microscopy, respectively. The X‐ray spectra of the PS matrix composite displayed the diffraction peak characteristic of the hybrid LDH basal plane at 2θ = 3.1 deg. The SAN matrix composite did not exhibit such a diffraction peak. Both PS and SAN composites displayed an intercalated type of morphology with respect to the LDH platelets, as assessed by transmission electron microscopy. A plasticizing effect due to the hybrid LDH particles was observed for all composites and was supported by a decrease in the glass‐transition temperature values and by Fourier transform infrared spectra. Besides tensile properties, the fracture toughness of the composites was compared with that of the pure polymers through the linear elastic fracture mechanics parameters. They were determined from fracture tests under a three‐point‐bending configuration. The results indicated that the effect of adding a small fraction of modified LDH particles to SAN caused an improvement in fracture toughness of 50% with respect to that of the pure polymer. Moreover, the relative increase in the fracture energy was about 200%. For PS matrix composites, both tensile properties and linear elastic fracture mechanics fracture parameters remained unaffected. These results were explained on the basis of the different plasticities developed by both polymers around the particles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(vinyl chloride‐co‐vinyl acetate‐co‐maleic anhydride)/silica nanocomposites derived from in situ suspension polymerization

Poly(vinyl chloride‐co‐vinyl acetate‐co‐maleic anhydride) (PVVM)/silica nanocomposites were prepared by the suspension radical copolymerization of the monomers in the presence of fumed silica premodified with γ‐methylacryloxypropl trimethoxy siliane. Morphological observation showed that the silica particles of nanometer scale were well dispersed in the copolymer matrix of the nanocomposites films, whereas silica particles tended to agglomerate in the composites films prepared by the solution blending of PVVM with silica. The experimental results show that the thermal stability, glass‐transition temperature, tensile strength, and Young's modulus were significantly enhanced by the incorporation of silica nanoparticles. The enhancement of properties was related to the better dispersion of silica particles in polymer matrix and the interaction between the polymer chains and the surfaces of the silica particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of peroxide crosslinking on the mechanical and morphological properties of poly(ethylene‐co‐vinyl acetate)/zeolite composites

Uncrosslinked and chemically crosslinked ethylene‐vinyl acetate copolymers (EVAs) with 5–25 volume percentages of zeolite were prepared in a melt‐mixing process and then compression‐molded on a hot‐press machine according to standard test specifications. The mechanical properties measured by tensile test showed a reduction in tensile strength and elongation at break with increasing zeolite content. However, an increasing trend was observed for tensile modulus with addition of zeolite. Experimental results for ultimate stress were compared with those from Pukanszky equation. The experimental data showed a good fit to the Pukanszky model. The improvement in the interfacial interaction for crosslinked composites was also confirmed by this model. Morphological changes of EVA/zeolite composites were analyzed by scanning electron microscopy (SEM). The fractured surface of the composites indicated more complex morphology at higher zeolite loading. The influence of crosslinking induced by 2 wt% of dicumyl peroxide on the properties of EVA/zeolite composites was also investigated. The crosslinked composites showed better tensile properties than the uncrosslinked ones, a result which might be an indication of enhanced interaction between the EVA and zeolite. Density measurements, gel content determinations, and Fourier transform infrared analyses were also performed to evaluate the crosslink content of the composites. The changes in the properties of chemically crosslinked EVA/zeolite composites were observed. Meanwhile, SEM micrographs of the crosslinked EVA/zeolite composites showed better interfacial strength between zeolite and the EVA matrix as compared to that of the uncrosslinked composites. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Effect of the chemical characteristics of mesoporous silica MCM‐41 on morphological,thermal, and rheological properties of composites based on polystyrene

Mesoporous silica nanoparticles (MCM‐41) with an average diameter of ～ 20 nm were synthesized by a sol‐gel method using binary surfactant system. Polystyrene (PS) composites containing mesoporous silica nanoparticles were prepared by in situ polymerization of styrene monomers. Similar in situ polymerized PS composites were prepared based on the modified silica functionalized with methyl and vinyl groups. The effects of silylation on thermal and rheological properties of the PS/silica composites are investigated. Of particular importance is that the in situ polymerization of monomers within the mesoporous silica may trap some polymer chains, if not all, thereby affording a greater physical interaction between polymer and the porous fillers, whereas the chemical modification of silica surface promotes the polymer–filler interaction, which in turn enhances the thermal stability of composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of alkali and silane treatment on the mechanical properties of jute‐fiber‐reinforced recycled polypropylene composites

Jute‐fibers‐reinforced thermoplastic composites are widely used in the automobile, packaging, and electronic industries because of their various advantages such as low cost, ease of recycling, and biodegradability. However, the applications of these kinds of composites are limited because of their unsatisfactory mechanical properties, which are caused by the poor interfacial compatibility between jute fibers and the thermoplastic matrix. In this work, four methods, including (i) alkali treatment, (ii) alkali and silane treatment, (iii) alkali and (maleic anhydride)‐polypropylene (MAPP) treatment, and (iv) alkali, silane, and MAPP treatment (ASMT) were used to treat jute fibers and improve the interfacial adhesion of jute‐fiber‐reinforced recycled polypropylene composites (JRPCS). The mechanical properties and impact fracture surfaces of the composites were observed, and their fracture mechanism was analyzed. The results showed that ASMT composites possessed the optimum comprehensive mechanical properties. When the weight fraction of jute fibers was 15%, the tensile strength and impact toughness were increased by 46 and 36%, respectively, compared to those of untreated composites. The strongest interfacial adhesion between jute fibers and recycled polypropylene was obtained for ASMT composites. The fracture styles of this kind of composite included fiber breakage, fiber pull‐out, and interfacial debonding. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers.     

Enhanced toughness of multilayer graphene‐filled poly(VInyl chloride) composites prepared using melt‐mixing method

In order to improve toughness of rigid poly(vinyl chloride) (PVC), we prepared multilayer graphene (MLG) filled PVC composites through conventional melt‐mixing methods by taking advantages of easy dispersion and high flexibility of graphene. Microstructure, static, and dynamic mechanical properties of the MLG/PVC composites were investigated in details. We found that a small amount of MLG loadings (0.36 wt%) could greatly increase tensile fracture toughness and impact strength of the MLG/PVC composites, which is mainly attributed to high flexibility of the crumpled MLG throughout PVC matrix. Moreover, the presence of MLG can weaken intermolecular interactions and improve segmental motion of PVC chains, consequently resulting in low glass transition temperature and high toughness of the MLG/PVC composites. By virtue of its enhanced toughness and easy operation, the MLG/PVC composites show great potential to be used as high‐performance composites in many fields. POLYM. COMPOS., 38:138–146, 2017. © 2015 Society of Plastics Engineers     

Ethylene–propylene copolymer/ordered polysilsesquioxane nanocomposites prepared via organic acid‐ or base‐catalyzed binary silica water‐crosslinking reactions

In situ silica sol–gel‐derived organic–inorganic hybrid materials, which comprise a vinyltrimethoxysilane‐grafted ethylene–propylene copolymer (EPR‐g‐VTMS) and n‐hexyltrimethoxysilane (HTMS), were successfully prepared in the presence of an organic acid and base catalyst. Benzenesulfonic acid and aniline were selected as the organic acid and base catalyst, respectively, to examine the progress and effect of progressive changes in the silane water‐crosslinking reaction of EPR‐g‐VTMS/HTMS composites. The water‐crosslinked EPR‐g‐VTMS/HTMS composites were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy, gel content, solid‐state ²⁹Si cross‐polarization/magic‐angle spinning NMR, wide‐angle X‐ray scattering, tensile strength and field‐emission scanning electron microscopy measurements. These results revealed that the type of catalyst has a substantial influence on the nature of siloxane bonds and eventually the physical tensile properties of the water‐crosslinked EPR‐g‐VTMS/HTMS composites, which can be explained mainly from knowledge of the traditional acid‐ and base‐catalyzed silica sol–gel reaction. Moreover, an in‐depth analysis of the aniline‐catalyzed composites indicated the formation of ladder‐type poly(n‐hexylsilsesquioxane)s and the presence of a highly ordered structure with a thickness equal to the length of two n‐hexyl groups in all‐trans conformation. We demonstrate potential for the future design of highly ordered silicate‐based organic–inorganic hybrid nanocomposites. Copyright © 2009 Society of Chemical Industry     

Magadiite/styrene‐butadiene rubber composites for tire tread applications: Effects of varying layer spacing and alternate inorganic fillers

Magadiite (MGD), a synthetic layered silicate (Na₂Si₁₄O₂₉·9H₂O) with surface chemistry similar to precipitated silica, was cation‐exchanged with three different organic cations to explore the effect of varying MGD layer spacing on the mechanical properties of MGD‐based styrene‐butadiene rubber (SBR) composites. This work also compares the mechanical properties of MGD/SBR composites with those formulated with montmorillonite (MMT) and precipitated silica. Dodecylpyridinium (DP⁺) produces greater expansion of MGD layers than cetyltrimethylammonium (CTA⁺); the resulting DP‐MGD/SBR composites have greater yield strain, toughness, and rubbery storage modulus than comparable CTA‐MGD/SBR composites. MGD treated with hexadecylammonium (HDA⁺) has the greatest layer spacing, but the HDA‐MGD layers collapse upon melt‐blending with SBR. CTA‐treated MMT (CMMT) exfoliates in aqueous suspension, but the platelets re‐stack upon drying and during melt‐blending with SBR. The presence of exfoliated and/or disordered platelet stacks in CMMT/SBR probably accounts for its higher tensile and dynamic moduli compared to MGD‐ and silica‐based SBR composites. Dynamic mechanical properties are used to predict tire tread performance metrics for these composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44764.     

Effects of palm ash loading and maleated natural rubber as a coupling agent on the properties of palm‐ash‐filled natural rubber composites

Natural rubber composites were prepared by the incorporation of palm ash at different loadings into a natural rubber matrix with a laboratory‐size two‐roll mill (160 × 320 mm²) maintained at 70 ± 5°C in accordance with the method described by ASTM D 3184–89. A coupling agent, maleated natural rubber (MANR), was used to improve the mechanical properties of the natural rubber composites. The results indicated that the scorch time and cure time decreased with increasing filler loading, whereas the maximum torque exhibited an increasing trend. Increasing the palm ash loading increased the tensile modulus, but the tensile strength, fatigue life, and elongation at break decreased. The rubber–filler interactions of the composites decreased with increasing filler loading. Scanning electron microscopy of the tensile fracture surfaces of the composites and rubber–filler interaction studies showed that the presence of MANR enhanced the interfacial interaction of the palm ash filler and natural rubber matrix. The presence of MANR also enhanced the tensile properties and fatigue life of palm‐ash‐filled natural rubber composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of silica nanoparticles on tribology performance of poly(Epoxy Resin‐Bismaleimide)‐based nanocomposites

Introduction of small nanoparticles into polymer matrix increases the mechanical, tribological, and thermal properties of nanocomposites. In this study, poly(epoxy resin‐bismaleimide‐diaminodiphenylmethane) (EP‐BMI‐DDM) copolymers filled with silica nanoparticles (SNPs) were successfully fabricated through in situ suspension polymerization. To enhance the interfacial adhesion of silica particles to the polymer matrix, the nanoparticles were organo‐modified by silane coupling agent. Results of tensile strength test revealed that increased toughness of the composites was attributed to the microcavitations induced by organo‐modified SNPs (OSNPs). Proper loadings of OSNPs can play a critical role in antifriction performance, with optimal friction coefficient of 0.17 (2 wt% OSNPs content). Thermostabilities of the nanocomposites were characterized by differential thermal gravimetric analysis. At the maximum rate of weight loss of EP‐BMI‐DDM/3 wt% OSNP, the temperature measured 452°C, which is 52°C higher than that of pure EP‐BMI‐DDM copolymers (400°C). The produced nanocomposites feature good thermostability and self‐lubrication can be widely used as wearable material under severe working conditions with higher temperature. POLYM. ENG. SCI., 59:274–283, 2019. © 2018 Society of Plastics Engineers     

Effects of copper amine treatment on mechanical properties of PVC/wood‐flour composites

Copper amine–treated wood flour was added to PVC [poly(vinyl chloride)] matrix in order to manufacture PVC/wood‐flour composites. Effects of copper treatments on the mechanical properties of PVC‐wood composites were evaluated. Unnotched impact strength, flexural strength, and flexural toughness of the composites were significantly improved by the wood‐flour copper treatment. The optimum copper concentration range was 0.2 to 0.6 wt% of wood flour. Fractured surfaces were examined by using scanning electron microscopy (SEM) combined with energy‐dispersive spectroscopy (EDS). PVC/wood interfacial debonding was the main fracture mode of untreated wood‐flour composites, whereas wood‐particle pullout and breakage dominating the fractured surfaces of copper‐treated wood‐flour composites. On the fractured surfaces, more PVC could be found on the exposed copper‐treated wood particles than on untreated wood, a result suggesting improved PVC‐wood interfacial adhesion after copper treatments. J. Vinyl Addit. Technol. 10:70–78, 2004. © 2004 Society of Plastics Engineers.