Toughened polyester matrices for advanced composites

An intercrosslinked network of hybrid bismaleimide (BMI) modified vinyl ester oligomer–unsaturated polyester matrix systems have been developed. Vinyl ester oligomer (VEO) was used as a toughening agent for unsaturated polyester resin and was added in 2, 4, and 6% (by wt). Benzoyl peroxide was used as curing agent. The VEO‐toughened unsaturated polyester matrix systems were further modified with 5, 10, and 15% (by wt) of bismaleimide. Bismaleimides modified vinyl ester–unsaturated polyester matrices were characterized by mechanical (tensile strength, flexural strength, tensile modulus, flexural modulus, and impact strength), thermal [differential scanning calorimetry (DSC), thermogravimetic analysis (TGA), heat deflection temperature analysis (HDT)] and morphological studies [scanning electron microscope (SEM)] and water absorption. Data obtained from mechanical studies indicated that the introduction of VEO into unsaturated polyester resin improves the fracture toughness. The introduction of BMI into VEO incorporated unsaturated polyester resin enhanced both thermal and mechanical behavior. The scanning electron micrographs of fractured surfaces of VEO‐modified unsaturated polyester systems and BMI modified vinyl ester–unsaturated polyester matrices illustrate the presence of homogeneous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 167–177, 2007     

MECHANICAL PROPERTIES OF BISMALEIMIDE (N,N′-BISMALEIMIDO-4,4′-DIPHENYL METHANE) - VINYL ESTER OLIGOMER (VEO) MODIFIED UNSATURATED POLYESTER INTERCROSSLINKED MATRICES FOR ADVANCED COMPOSITES

An intercrosslinked network of varying percentages of N,N′-bismaleimido-4,4′-disphenyl methane (BMI), vinyl ester oligomer (VEO) modified unsaturated polyester (UP) matrices have been developed. Vinyl ester oligomer was prepared by reacting commercially available epoxy resin GY 250 (Ciba-Geigy) and acrylic acid was used as toughening agent for unsaturated polyester resin. BMI-VEO-UP matrices were characterized for their mechanical properties, viz tensile strength, flexural strength and unntoched Izod impact test as per ASTM standards. The dielectric strength and water absorption measurements were also performed according to ASTM standards. Data obtained from mechanical studies, dielectric strength and water absorption indicate that the introduction of VEO into unsaturated polyester resin improves mechanical properties and affects the moisture resistance according to its percentage concentration. The incorporation of BMI into the VEO modified unsaturated polyester system improves mechanical properties, dielectric strength and resistance to moisture absorption according to its percentage concentration.     

Preparation and characterization of bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane)–unsaturated polyester modified epoxy intercrosslinked matrices

An intercrosslinked network of unsaturated polyester–bismaleimide modified epoxy matrix systems was developed. Epoxy systems modified with 10, 20, and 30% (by weight) of unsaturated polyester were made by using epoxy resin and unsaturated polyester with benzoyl peroxide and diaminodiphenylmethane as curing agents. The reaction between unsaturated polyester and epoxy resin was confirmed by IR spectral studies. The unsaturated polyester toughened epoxy systems were further modified with 5, 10, and 15% (by weightt) of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were performed to determine the glass transition temperature (T_g) and thermal degradation temperature of the systems, respectively. Mechanical properties, viz: tensile strength, flexural strength, and plain strain fracture toughness of intercrosslinked epoxy systems, were studied by ASTM methods. Data obtained from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improves toughness but with a reduction in glass transition, whereas the incorporation of bismaleimide into epoxy resin improved both mechanical strength and thermal behavior of epoxy resin. The introduction of bismaleimide into unsaturated polyester‐modified epoxy resin altered thermomechanical properties according to their percentage concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2853–2861, 2002     

Preparation and characterization of siliconized epoxy/bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane) intercrosslinked matrices for engineering applications

Novel hybrid intercrosslinked networks of hydroxyl‐terminated polydimethylsiloxane‐modified epoxy and bismaleimide matrix systems have been developed. Epoxy systems modified with 5, 10, and 15 wt % of hydroxyl‐terminated polydimethylsiloxane (HTPDMS) were developed by using epoxy resin and hydroxyl‐terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane (γ‐APS) as compatibilizer and dibutyltindilaurate as catalyst. The reaction between hydroxyl‐terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15 wt % of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry and thermogravimetric analysis of the matrix samples were also performed to determine the glass‐transition temperature and thermal‐degradation temperature of the systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy improves the toughness and thermal stability of epoxy resin with reduction in strength and modulus values. Similarly the incorporation of bismaleimde into epoxy resin improved both tensile strength and thermal behavior of epoxy resin. However, the introduction of siloxane and bismaleimide into epoxy enhances both the mechanical and thermal properties according to their percentage content. Among the siliconized epoxy/bismaleimide intercrosslinked matrices, the epoxy matrix having 5% siloxane and 15% bismaleimide exhibited better mechanical and thermal properties than did matrices having other combinations. The resulting siliconized (5%) epoxy bismaleimide (15%) matrix can be used in the place of unmodified epoxy for the fabrication of aerospace and engineering composite components for better performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 38–46, 2001     

Preparation and characterization of 3,3′‐bis (maleimidophenyl)phenylphosphine oxide (BMI)/polysulfone modified epoxy intercrosslinked matrices

An intercrosslinked network of polysulfone (PSF)—bismaleimide (BMI) modified epoxy matrix system was made by using diglycidyl ether of bisphenol A (DGEBA) epoxy resin, hydroxyl terminated polysulfone and bismaleimide (3,3′‐bis(maleimidophenyl) phenylphosphine oxide) with diaminodiphenylmethane (DDM) as curing agent. BMI–PSF–epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and heat deflection temperature (HDT) analysis. The matrices, in the form of castings, were characterized for their mechanical properties such as tensile strength, flexural strength, and unnotched Izod impact test as per ASTM methods. Mechanical studies indicated that the introduction of polysulfone into epoxy resin improves the toughness to an appreciable extent with insignificant increase in stress–strain properties. DSC studies indicated that the introduction of polysulfone decreases the glass transition temperature, whereas the incorporation of bismaleimide into epoxy resin influences the mechanical and thermal properties according to its percentage content. DSC thermograms of polysulfone as well as BMI modified epoxy resin show a unimodal reaction exotherm. The thermal stability and flame retardant properties of cured epoxy resins were improved with the introduction of bismaleimide and polysulfone. Water absorption characteristics were studied as per ASTM method and the morphology of the BMI modified epoxy and PSF‐epoxy systems were studied by scanning electron microscope. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Studies on mechanical,thermal, and morphology of diglycidylether‐terminated polydimethylsiloxane‐modified epoxy–bismaleimide matrices

An epoxy matrix system modified by diglycidylether‐terminated polydimethylsiloxane (DGETPDMS) and bismaleimide (BMI) was developed. Epoxy systems modified with 4, 8, and 12% (by wt) of DGETPDMS were made using epoxy resin and DGETPDMS, with diaminodiphenylmethane as the curing agent. The DGETPDMS‐toughened epoxy systems were further modified with 4, 8, and 12% (by wt) of BMI, namely (N,N′‐bismaleimido‐4,4′‐diphenylmethane). DGETPDMS/BMI/epoxy matrices were characterized using differential scanning calorimetry, thermogravimetric analysis, and heat deflection temperature analysis. The matrices, in the form of castings, were characterized for their mechanical properties, viz. tensile strength, flexural strength, and impact test, as per ASTM methods. Mechanical studies indicate that the introduction of DGETPDMS into epoxy resin improves the impact strength, with reduction in tensile strength, flexural strength, and glass transition temperature, whereas the incorporation of BMI into epoxy resin enhances the mechanical and thermal properties according to its percentage content. However, the introduction of both DGETPDMS and BMI enhances the values of thermomechanical properties according to their percentage content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 668–674, 2006     

Mechanical characterization and chemical resistances of cured unsaturated polyester resins modified with vinyl ester resins based on recycled poly(ethylene terephthalate)

Unsaturated polyester resin (UP) was prepared from glycolyzed oligomer of poly(ethylene terephthalate) (PET) waste based on diethylene glycol (DEG). New diacrylate and dimethacrylate vinyl ester resins prepared from glycolysis of PET with tetraethylene glycol were blended with UP to study the mechanical characteristics of the cured UP. The vinyl ester resins were used as crosslinking agents for unsaturated polyester resin diluted with styrene, using free‐radical initiator and accelerator. The mechanical properties of the cured UP resins were evaluated. The compressive properties of the cured UP/styrene resins in the presence of different vinyl ester concentrations were evaluated. Increasing the vinyl ester content led to a pronounced improvement in the compression strength. The chemical resistances of the cured resins were evaluated through hot water, solvents, acid, and alkali resistance measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3175–3182, 2007     

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d ₀₀₁ reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).     

Preparation and characterization of chain‐extended bismaleimide modified polyurethane–epoxy matrices

Intercrosslinked networks of bismaleimide (BMI) modified polyurethane–epoxy systems were prepared from chain‐extended BMI and polyurethane modified epoxy and cured in the presence of 4,4′‐diaminodiphenylmethane. Infrared spectral analysis was used to confirm the grafting of polyurethane onto the epoxy skeleton. The prepared matrices were characterized by mechanical, thermal, and morphological studies. The results, obtained from the mechanical and thermal studies, reveal that the incorporation of polyurethane into epoxy increases the mechanical strength and decreases the glass‐transition temperature and thermal stability. The incorporation of chain‐extended BMI into polyurethane modified epoxy systems increases the thermal stability and both tensile and flexural properties, and decreases the impact strength and glass‐transition temperature. Surface morphologies of polyurethane modified epoxy and chain‐extended BMI modified polyurethane– epoxy systems were studied by scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1562–1568, 2003     

Silica nanoparticles modified with vinyltriethoxysilane and their copolymerization with N,N′‐bismaleimide‐4,4′‐diphenylmethane

The synthesis and characterization of the vinyltriethoxysilane‐modified silica nanoparticles were investigated. It was shown that the vinyltriethoxysilane molecules had been successfully grafted onto the silica nanoparticles. The native and silane‐modified silica dispersions in N‐methyl‐2‐pyrrolidone with the total solids contents within the range 1–6 wt % exhibited dramatically different flow behaviors. The polymerization of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) initiated by barbituric acid in the presence of the native or vinyltriethoxysilane‐modified silica nanoparticles were then carried out in γ‐butyrolactone (total solids content = 20%). The higher the level of silica, the better the thermal stability of the BMI/silane/silica composite particles. The silane‐modified silica particles significantly improved their dispersion capability within the continuous BMI oligomer matrix. Furthermore, the degree of dispersion of the vinyltriethoxysilane‐modified silica particles in the BMI oligomer matrix decreased with the weight percentage of silica based on total solids increased from 20 to 40 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: Sci 103: 3600–3608, 2007     

Mechanical,thermal, and morphological properties of bismaleimide/unsaturated polyester copolymers

An unsaturated polyester (UP) resin was modified by the addition of a thermosetting bismaleimide (BMD) as a second coreactive monomer. The copolymers were characterized in terms of mechanical, thermal, and morphological properties by tensile, bend, and impact testing; thermogravimetric analysis; heat deforming temperature analysis; dynamic mechanical analysis; and scanning electron microscopy. In addition, Fourier transform infrared spectroscopy of modified resin indicated that crosslinking networks were formed between BMD and UP. The properties of the modified resins were compared with those of unmodified resins. The results indicate that the addition of BMD not only improved the thermal decomposition temperature and heat deforming temperature but also caused small changes in the mechanical properties. The effect of the construct of BMD and the reactions among BMD, UP, and styrene were analyzed. The results show that BMD has great potential to improve the properties of UP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 593–598, 2006     

Acetyl‐capped paraformaldehyde as crosslinking agent for BMI‐modified novolac resin for resin transfer molding

Paraformaldehyde was end‐capped with acetyl groups and was applied as a crosslinking agent for a bismaleimide (BMI)‐modified novolac resin system. The processibility of the resin system containing 5 wt % crosslinking agent still met the need for resin transfer molding (RTM), whereas the thermomechanical properties of crosslinked resin improved significantly. The composites based on the resin system and woven glass fabric showed better flexural strength, modulus, and higher retention rates at 200 and 300°C than that based on a resin system without acetyl‐capped paraformaldehyde. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1265–1271, 2002     

Unsaturated polyester–poly(ε‐caprolactone) hybrid nanocomposites: Thermal–mechanical properties

This paper reports on the thermal behavior and mechanical properties of nanocomposites based on unsaturated polyester resin (UP) modified with poly(ɛ‐caprolactone) (PCL) and reinforced with an organically modified clay (cloisite 30B). To optimize the dispersion of 30B and the mixing of PCL in the UP resin, two different methods were employed to prepare crosslinked UP–PCL‐30B hybrid nanocomposites. Besides, two samples of poly(ɛ‐caprolactone) of different molecular weight (PCL2: M_n = 2.10³g.mol⁻¹ and PCL50: M_n = 5.10⁴g.mol⁻¹) were used at several concentrations (4, 6, 10 wt%). The 30B concentration was 4 wt% in all the nanocomposites. The morphology of the samples was studied by scanning electron microscopy (SEM). The analysis of X‐ray patterns reveals that intercalated structures have been found for all ternary nanocomposites, independently of the molecular weight, PCL concentration and the preparation method selected. A slight rise of the glass transition temperature, T_g, is observed in UP/PCL/4%30B ternary nanocomposites regarding to neat UP. The analysis of the tensile properties of the ternary (hybrid) systems indicates that UP/4%PCL2/4%30B nanocomposite improves the tensile strength and elongation at break respect to the neat UP while the Young modulus remains constant. POLYM. COMPOS., 35:827–838, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of siliconized epoxy‐1,2‐bis(maleimido)ethane intercrosslinked matrix materials

Novel intercrosslinked networks of siliconized epoxy‐1,2‐bis(maleimido)ethane matrix systems are developed. The siliconization of epoxy resin is carried out by using 5–15% hydroxyl‐terminated poly(dimethylsiloxane) with γ‐aminopropyltriethoxysilane as a crosslinking agent and dibutyltin dilaurate as a catalyst. The siliconized epoxy systems are further modified with 5–15% 1,2‐bis(maleimido)ethane and cured by using diaminodiphenylmethane. The prepared neat resin castings are characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into these epoxy resins improves the toughness with a reduction in the stress–strain values, whereas incorporation of bismaleimide (BMI) into the epoxy resin improves the stress–strain properties with a lowering of the toughness. The introduction of both siloxane and BMI into the epoxy resin influences the mechanical properties according to their content percentages. Differential scanning calorimetry (DSC), thermogravimetry, and heat distortion temperature analyses are also carried out to assess the thermal behavior of the matrix materials that are developed. DSC thermograms of the BMI modified epoxy systems show unimodal reaction exotherms. The glass‐transition temperature, thermal degradation temperature, and heat distortion temperature of the cured BMI modified epoxy and siliconized epoxy systems increase with increasing BMI content. The water absorption behavior of the matrix materials is also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3808–3817, 2003     

Preparation and characterization of unsaturated poly(ester‐imide) based on 1,4‐bis[2′‐trifluoromethyl‐4′‐(4″‐glycolformate)‐trimellitimidophenoxy]benzene

A novel diimidodialcohol monomer, 1,4‐bis[2′‐trifluoromethyl‐4′‐(4″‐glycolformate)‐ trimellitimidophenoxy]benzene (BGTB), was synthesized and characterized. It was reacted with isophthalic acid, maleic anhydride and propylene glycol to produce a novel unsaturated poly(ester‐imide) (BGTB‐UPEI) with imide and trifluoromethyl groups in the polymer backbone. The BGTB‐UPEI resin was diluted with reactive monomer (styrene) to give a low‐viscous poly(ester‐imide)/styrene (BGTB‐UPEI/St) mixed solution, which was then thermally cured to yield thermosetting BGTB‐UPEI/St composite. The effect of processing parameters such as the curing temperature and curing time, reactive monomer concentration and initiator amount on the curing reaction was systematically investigated. Experimental results indicated that the thermally cured BGTB‐UPEI/St composite exhibited much better thermal, mechanical, electrical insulating properties and chemical resistance than the standard unsaturated polyester/polystyrene composite. Copyright © 2006 Society of Chemical Industry     

Effects of reactive low‐profile additives on the properties of cured unsaturated polyester resins. II. Glass‐transition temperature and mechanical properties

The effects of reactive poly(methyl methacrylate) (PMMA) and poly(vinyl acetate)‐block‐poly(methyl methacrylate) (PVAc‐b‐PMMA) as low‐profile additives (LPAs) on the glass‐transition temperature and mechanical properties of low‐shrink unsaturated polyester resin (UP) were investigated by an integrated approach of determining static phase characteristics, reaction kinetics, cured sample morphology, and property measurements. The factors that, according to Takayanagi mechanical models, control the glass‐transition temperature in each phase region of the cured samples, as identified by both the thermally stimulated currents method and dynamic mechanical analysis, and the mechanical properties are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 867–878, 2006     

Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)

Aromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001     

A comparative study on the preparation and characterization of aromatic and aliphatic bismaleimides‐modified polyurethane–epoxy interpenetrating polymer network matrices

Interpenetrating polymer networks of bismaleimide‐modified polyurethane–epoxy systems were prepared using the aliphatic and aromatic bismaleimides‐ and polyurethane‐modified epoxy and cured in the presence of 4,4′‐diaminodiphenylmethane. Infrared spectral analysis was used to confirm the polyurethane‐crosslinked epoxy (PU–EP). The matrices developed were characterized by mechanical, thermal, electrical, and morphological studies. The results obtained from the mechanical studies indicate that the incorporation of polyurethane and bismaleimides into epoxy increased the tensile strength, flexural strength, and impact strength, according to their nature and percentage concentration. The results obtained from the thermal and electrical studies indicate that the incorporation of polyurethane into epoxy decreased the thermal properties (glass transition temperature, heat distortion temperature (HDT), thermal stability) and electrical properties (dielectric strength, volume and surface resistivity, and arc resistance). The incorporation of aromatic bismaleimide into the polyurethane‐modified epoxy system increased the glass transition temperature, thermal stability, and electrical properties. Decreased values of glass transition and HDT were obtained in the case of aliphatic bismaleimide‐modified polyurethane–epoxy system. Surface morphology of modified epoxy systems was studied using scanning electron microscopy, and it was found that the polyurethane‐modified epoxy systems exhibited heterogeneous morphology and bismaleimides‐modified epoxy systems showed a homogeneous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3592–3602, 2006     

Thermal and mechanical properties of functionalized mullite reinforced unsaturated polyester composites

This work studies the development of varying weight percentages (0.5, 1.0, and 1.5 wt%) of surface functionalized mullite reinforced unsaturated polyester (UP) composites and their thermal, dielectric, water absorption, and mechanical properties. The synthesized mullite was functionalized with vinyltriethoxysilane (VTES). The introduction of vinyl groups on the surface of mullite was confirmed by FT‐IR, TGA, and X‐ray diffraction (XRD) analyses. Varying weight percentages (0.5, 1.0 and 1.5 wt%) of vinyl functionalized mullite (VFM) were incorporated into UP resin with a benzoyl peroxide initiator to obtain composites. The resultant data obtained from thermal, mechanical, dielectric, and water absorption studies, indicate that incorporation of VFM, leads to a significant improvement in the thermo mechanical, dielectric, and moisture resistant properties of the UP composites, compared with those of neat UP matrices. The molecular dispersion of VFM fiber in reinforced UP matrix composites was confirmed by SEM analysis. POLYM. COMPOS., 35:1663–1670, 2014. © 2013 Society of Plastics Engineers     

Chemosetting resins containing fillers. I. Unsaturated polyester resin compositions containing modified smectites

Smectic clays with quaternary ammonium salts (QAS) were subjected to hydrophobization, whereupon we applied the products in attempts to modify various polymers. The clays were of natural origin and contained a large proportion of montmorillonite and an original method of modification was applied. A significant improvement of the stability of unsaturated polyester (UP) resins, modified with clays modified with QAS, was observed with essentially no change in the reactivity of resins. The compositions of polyester resins containing 2 wt % of modified smectites had excellent thixotropy. The presence of modified bentonites in a cured commercial UP resin (2–4 wt %) improved its tensile strength (by 21–62%), Brinell hardness (23–70%), and unnotched impact strength (23–100%), depending on the type of bentonite used. The compositions of UP resins with modified clays had certain properties typical for nanocomposites: improved stiffness, strength, transparency, and fine‐lamellar morphology of the fracture as found by electron scanning microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 793–801, 2005