Synthesis of EP‐POSS mixture and the properties of EP‐POSS/epoxy,SiO2/epoxy,and SiO2/EP‐POSS/epoxy nanocomposite

The hybrid material of EP‐POSS mixture was synthesized by the hydrolysis and condensation of (γ‐glycidoxypropyl) trimethoxysilane. A series of binary systems of EP‐POSS/epoxy blends, epoxy resin modified by silica nanoparticles (SiO₂/epoxy), and ternary system of SiO₂/EP‐POSS/epoxy nanocomposite were prepared. The dispersion of SiO₂ in the matrices was evidenced by transmission electron micrograph, and the mechanical properties, that is, flexural strength, flexural modulus, and impact strength were examined for EP‐POSS/epoxy blends, SiO₂/epoxy, and SiO₂/EP‐POSS/epoxy, respectively. The fractured surface of the impact samples was observed by scanning electron micrograph. Thermogravimetry analysis were applied to investigate the different thermal stabilities of the binary system and ternary system by introducing EP‐POSS and SiO₂ to epoxy resin. The results showed that the impact strength, flexural strength, and modulus of the SiO₂/EP‐POSS/epoxy system increased around by 57.9, 14.1, and 44.0% compared with the pure epoxy resin, T_i, T_max and the residues of the ternary system were 387°C, 426°C, and 25.2%, increased remarkably by 20°C, 11°C and 101.6% in contrast to the pure epoxy resin, which was also higher than the binary systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 810‐819, 2013     

Cationic polymerization behavior of β‐methylglycidyl ether derivatives and physical properties of their cationically cured materials

β‐Methylglycidyl ethers have been applied to Electrical and Electronic adhesives. However, there is no report about the detailed polymerization behavior and physical properties of their cured products. Hence, we investigated cationic polymerization behavior of bisphenol A di(β‐methylglycidyl) ether (Me‐BADGE) and physical properties of the cured products containing Me‐BADGE. DSC analysis suggested that Me‐BADGE could be cured completely at lower temperature than bisphenol A diglycidyl ether (BADGE). Physical properties were analyzed by dynamic viscoelastic analysis. Glass transition temperature (T_g) of BADGE homopolymer was 194°C. In contrast, the copolymer of BADGE (50 wt %) with Me‐BADGE (50 wt %) showed T_g at 124°C. According to the data of E’ and tan δ, crosslink density of the cured products decreased with increasing the Me‐BADGE content. The analysis of cationic polymerization of monofunctional β‐methylglycidyl ether suggested that the cationic polymerization proceeded not only through oxonium cation but also through carbocation formed by ring‐opening reaction of oxonium cation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42377.     

Effect of starch predrying on the mechanical properties of starch/poly(ε‐caprolactone) composites

This study describes the effect of predrying sago starch, a tropical starch, on the resultant mechanical properties of starch/poly(ε‐caprolactone) composite materials. Sago starch was dried to less than a 1% moisture level in a vacuum oven and dispersed into a polycaprolactone matrix with an internal mixer at 90°C. The mechanical properties of the composite were studied according to methods of the Association for Standards, Testing, and Measurement, whereas the morphology was monitored with scanning electron microscopy. The properties were compared with a composite obtained with native starch containing 12% moisture. The results indicated that predrying the starch led to a lower property drop rate in the composite as the starch content increased. The elastic modulus, tensile strength, and elongation at break were higher than those obtained when starch was used without predrying. The morphology observed during scanning electron microscopy studies was used to explain the observed trends in the mechanical properties. In this way, a relatively simple and cost‐effective method was devised to increase the starch loading in the polycaprolactone matrix to obtain properties within the useful range of mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 877–884, 2003     

Influence of cure conditions on out‐of‐autoclave bismaleimide composite laminates

Bismaleimides (BMI) are thermosetting polymers that are widely used in the aerospace industry due to their good physical properties at elevated temperatures and humid environments. BMI‐based composites are used as a replacement for conventional epoxy resins at higher service temperatures. Out‐of‐Autoclave (OOA) processing of BMI composites is similar to that of epoxies but requires higher cure temperatures. Polymer properties such as degree of cure and crosslink density are dependent on the cure cycle used. These properties affect mechanical strength as well as glass transition temperature of the composite. In the current research, carbon fiber/BMI composite laminates were manufactured by OOA processing. The void content was measured using acid digestion techniques. The influence of cure cycle variations on glass transition temperature and mechanical strength was investigated. Properties of manufactured specimens were compared with that of conventional autoclave cured BMI composites. Laminates fabricated via OOA processing exhibited properties comparable to that of autoclave cured composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43984.     

Mechanical properties and densification behavior of β‐spodumene/anorthite composites

Although β‐spodumene/anorthite composites are interesting systems, little research work has been done to study their properties. This study aims at investigating the preparation and properties of β‐spodumene/anorthite composites containing β‐spodumene proportions ranging between 10 and 25 mass %. X‐ray diffraction analysis (XRD), Scanning electron microscopy (SEM), and the coefficient of thermal expansion (CTE) were used to characterize the effect of addition of β‐spodumene on the phase relations, microstructure, and thermal expansion behavior of resultant composites. The results show that the presence of β‐spodumene significantly reduces the porosity and reduces the densification temperature. It reduces thermal expansion and enhances the mechanical properties of anorthite‐containing composites.     

Investigation of mechanical properties of alumina nanoparticle‐loaded hybrid glass/carbon‐fiber‐reinforced epoxy composites

This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1–5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1–5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39749.     

Synthesis,thermal, and dynamic mechanical properties of 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane‐containing polydimethylsiloxanes

New and effective approaches to the synthesis of 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane‐containing polydimethylsiloxanes ( P1 and P2 ) were developed. P1 was obtained by polycondensation of cyclodisilazane lithium salt and chloroterminated polydimethylsiloxane. P2 was produced by hydrosilylation of vinyl‐terminated cyclodisilazane and hydrogen‐terminated polydimethylsiloxane. The polycondensation completed quickly at room temperature, while the hydrosilylation was facile and did not require cumbersome air‐sensitive operations. P1 and P2 were characterized by Fourier transform infrared, nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis (TGA), and isothermal gravimetric analysis (IGA). TGA revealed the outstanding thermal properties of P1 and P2 with 5% weight loss temperatures (T_d5) higher than 450°C. IGA proved their better thermal stability at 450°C for 800 min, compared to polydimethyldiphenylsiloxane. Dynamic mechanical analysis showed that silicone rubbers made from cyclodisilazane‐containing polydimethylsiloxanes could have a maximum tan δ value as high as 1.13 and had good prospects for damping material applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of bisphenol A‐based bis‐phthalonitrile composite laminates

A series of bisphenol A (BPA)‐based 2,2‐bis‐[4‐(3,4‐dicyanophenoxy)phenyl]propane (BAPh) prepolymers and polymers were prepared using BPA as a novel curing agent. Ultraviolet–visible and Fourier transform infrared spectroscopy spectrum were used to study the polymerization reaction mechanism of the BAPh/BPA polymers. The curing behaviors were studied by differential scanning calorimetry and dynamic rheological analysis, the results indicated that the BAPh/BPA prepolymers exhibit large processing windows (109.5–148.5°C) and low complex viscosity (0.1–1 Pa·s) at moderate temperature, respectively. Additionally, the BAPh/BPA/glass fiber (GF) composite laminates were manufactured and investigated. The flexural strength and modulus of the composite laminates are 548.7–632.8 MPa and 25.7–33.2 GPa, respectively. The thermal stabilities of BAPh/BPA/GF composite laminates were studied by thermogravimetry analysis. The temperatures at 5% weight loss (T_5%) of the composite laminates are 508.5–528.7°C in nitrogen and 508.1–543.2°C in air. In conclusion, the BAPh/BPA systems can be used as superior matrix materials for numerous advanced composite applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of processing conditions on mechanical and viscoelastic properties of biocomposites

To study the effects of processing conditions on the viscoelastic and mechanical properties of biodegradable composites, we prepared several composites based on sisal fibers and biodegradable polymers. The effects of processing conditions such as the speed of rotation, temperature, and time of mixing were investigated. The mechanical and viscoelastic properties of these composites were affected by the processing conditions. This was principally due to the modification of the initial aspect ratio of the natural fibers as a result of the shear stresses that developed in the mixer during the compounding. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1637–1642, 2003     

Effect of quasi‐carbonization processing parameters on the mechanical properties of quasi‐carbon/phenolic composites

In this work, quasi‐carbon fabrics were produced by quasi‐carbonization processes conducted at and below 1200°C. Stabilized polyacrylonitrile (PAN) fabrics and quasi‐carbon fabrics were used as reinforcements of phenolic composites with a 50 wt %/50 wt % ratio of the fabric to the phenolic resin. The effect of the quasi‐carbonization process on the flexural properties, interfacial strength, and dynamic mechanical properties of quasi‐carbon/phenolic composites was investigated in terms of the flexural strength and modulus, interlaminar shear strength, and storage modulus. The results were also compared with those of a stabilized PAN fabric/phenolic composite. The flexural, interlaminar, and dynamic mechanical results were quite consistent with one another. On the basis of all the results, the quasi‐static and dynamic mechanical properties of quasi‐carbon/phenolic composites increased with the applied external tension and heat‐treatment temperature increasing and with the heating rate decreasing for the quasi‐carbonization process. This study shows that control of the processing parameters strongly influences not only the mechanical properties of quasi‐carbon/phenolic composites but also the interlaminar shear strength between the fibers and the matrix resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dynamic mechanical properties of three‐component composites (acrylic polymer/epoxy/SiO2) in the glass‐transition region

In previous studies, we reported the linear and nonlinear rheological properties of three‐component composites consisting of acrylic polymer (AP), epoxy resin (EP), and various SiO₂ contents (AP/EP/SiO₂) in the molten state. In this study, the dynamic mechanical properties of AP/EP/SiO₂ composites with different particle sizes (0.5 and 8 μm) were investigated in the glass‐transition region. The EP consisted of three kinds of EP components. The α relaxation due to the glass transition shifted to a higher temperature with an increase in the volume fraction (?) for the AP/EP/SiO₂ composites having a particle size of 0.5 μm, but the α relaxation scarcely shifted for the composite having a particle size of 8 μm as a general result. This result suggested that the SiO₂ nanoparticles that were 0.5 μm in size adsorbed a lot of the low‐glass‐transition‐temperature (T_g) component because of their large surface area. The AP/SiO₂ composites did not exhibit a shift in T_g; this indicated that the composite did not adsorb any component. The modulus in the glassy state (E′_g) exhibited a very weak &phis; dependence for the AP/EP/SiO₂ composites having particle sizes of 0.5 and 8 μm, although E′_g of the AP/SiO₂ composites increased with &phis;. The AP/EP/SiO₂ composites exhibited a peculiar dynamic mechanical behavior, although the AP/SiO₂ composites showed the behavior of general two‐component composites. Scanning electron microscopic observations indicated that some components in the EP were adsorbed on the surface of the SiO₂ particles. We concluded that the peculiar behavior of the AP/EP/SiO₂ composites was due to the selective adsorption of the EP component. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40409.     

多壁碳纳米管／环氧树脂复合材料性能研究

采用物理机械方法与化学方法相结合的手段,制备了多壁碳纳米管（MWNTS）／环氧树脂（Epoxy）复合材料。通过力学拉伸试验测试了MWNTs/Epoxy复合材料拉伸强度和拉伸模量与MWNTS添加量的关系,利用扫描电镜（SEM）分析了MWNTS／Epoxy复合材料的拉伸断面,并用表面电阻测试仪对所制备的碳纳米管复合材料进行了电学性能测试。结果表明：经过化学酸化的方法处理后的MWNTS在复合材料中的分散得到了改善,力学性能也得到了明显的提高,但酸处理后的复合材料的电学性能明显低于未处理的复合材料。     

The mechanical properties of β‐Si3N4 whiskers‐reinforced dental resin composites

The surface‐modified β‐Si₃N₄ whiskers were used as inorganic fillers to reinforce dental resin (Bis‐GMA/TEGDMA) matrix with filler level ranging from 0 to 60 wt %. The experimental results indicated that the fracture strength of the composites increased from 79.85 to 139.8 MPa with increasing the whiskers loading. The compressive strength, elastic modulus, and rockwell hardness all increased monotonously with increasing filler level. Furthermore, thermal cycling did not decrease the fracture strength of the composites. Moreover, the composites showed good biocompatibility to support MG63 cells adhesion and proliferation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40692.     

Tensile properties of glass microballoon‐epoxy resin syntactic foams

The effect of hollow glass particle (microballoon) volume fraction in the range of 0.3–0.6 on the tensile properties and fracture mode of syntactic foams is characterized in the present research. Sixteen types of syntactic foams have been fabricated and tested. Four types of glass microballoons, having 220, 320, 380, and 460 kg/m³ density, are used with epoxy resin matrix for making the syntactic foam samples. These foams contain 30, 40, 50 and 60% microballoons by volume. All types of microballoons have the same size but different wall thickness, which reflects as a difference in their density. It is observed that the tensile strength increases with a decrease in the volume fraction of microballoons. All types of syntactic foams showed 60–80% decrease in the tensile strength compared with that of the neat resin. The foams containing low strength microballoons showed lower tensile modulus compared with that of the neat resin, but the presence of high strength microballoons led to an increase in the tensile modulus of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1254–1261, 2006     

Preparation and properties of aluminum nitride‐filled epoxy composites: Effect of filler characteristics and composite processing conditions

Polymer‐matrix composites based on brominated epoxy as the matrix and aluminum nitride (AlN) particle as the filler were prepared. Effects of AlN size and content as well as composite processing conditions on the preparation and properties of the composites had been investigated. At the same processing conditions, Young's modulus (E) and dielectric constant (D_k) of the composites increase, whereas coefficient of thermal expansion decreases when increasing AlN content or decreasing AlN size; tensile strength and elongation at break first increase then decrease with AlN content, and they reach maximum values at lower AlN content with decreasing AlN size; glass transition temperature (T_g) also exhibits a trend of first increase then decrease with AlN content, and it decreases with decreasing AlN size, especially at high AlN content; dissipation factor (D_f) generally decreases with AlN content except for the composites filled with 50 nm‐AlN, and it increases with decreasing AlN size. Comparing the composites prepared at different processing conditions, the properties of the composite are relatively poor at low vacuum conditions during removal of solvent and bubble. The scanning electron microscope and Fourier transform infrared analyses indicate that the properties of the composites are related to the aggregation of AlN filler and voids in the composites as well as the crosslink density of epoxy matrix. The preparation of the composites is also found to be affected by AlN size and content as well as vacuum conditions, indicating that increase of viscosity of system and/or the solvent evaporation during curing results in poor formability of the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐based biocomposites reinforced with kenaf fibers

Biodegradable thermoplastic‐based composites reinforced with kenaf fibers were prepared and characterized. Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), produced by bacterial fermentation, was selected as polymeric matrix. To improve PHBV/fibers adhesion, low amount of a proper compatibilizing agent, obtained by grafting maleic anhydride onto PHBV, was added during matrix/fibers melt mixing (reactive blending). When compared with uncompatibilized composites, the presence of the compatibilizer induces a stronger interfacial adhesion and a more pronounced improvement of the mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of facile amine‐functionalization on the physical properties of epoxy/graphene nanoplatelets nanocomposites

Graphene nanoplatelets (GNPs) have excellent thermal, electrical, and mechanical properties. The incorporation of GNPs into a polymer can remarkably enhance the thermal and mechanical properties of the polymer especially when GNPs are well dispersed in the polymer matrix with strong interfacial bonding. Therefore, in this study, GNPs were amine‐functionalized by covalently bonding 4,4′‐methylene dianiline onto their surfaces via a facile synthetic route. The amine‐functionalization was confirmed by FTIR spectroscopy and TGA. Epoxy/GNPs nanocomposites were prepared and their curing behavior, thermomechanical properties and impact strength were investigated. The amine‐functionalization increased curing rate, storage modulus, thermal dimensional stability, and impact strength of the nanocomposites. The SEM images for the fracture surface of the nanocomposite with amine‐functionalized GNPs showed a smooth and ductile failure‐like surface, resulted from the improved interfacial bonding between GNPs and the epoxy matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42269.     

Effect of the processing techniques on the properties of ecocomposites based on vegetable oil‐derived Mater‐Bi® and wood flour

Polymer composites based on biodegradable polymers and natural‐organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater‐Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater‐Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas single‐screw extrusion followed by calendering and twin‐screw extrusion provoked an increase of the elastic modulus and of the viscosity. The use of wood flour led to a significant increase of the rigidity, whereas a reduction of the ductility was observed. Because of the very similar aspect ratios of the two different filler size classes, no dramatic differences in the properties were found. These results are useful in order predicting and setting up the optimum preparation and processing strategy for the production of fully biodegradable polymer composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of grafted polypropylene on the mechanical properties of mineral‐filled polypropylene composites

The purpose of this work was to study how mineral fillers would behave in a polypropylene (PP) matrix when PP modified with maleic anhydride (MA) and/or itaconic acid (IA) was used as a coupling agent in the preparation of mineral‐filled PP composites. The composites were characterized with tensile mechanical measurements and morphological analysis. The optimum amount of the coupling agent to be used to obtain composites with improved mechanical properties was established. The results indicated that these coupling agents enhanced the tensile strength of the composites significantly, and the extent of the coupling effect depended on the nature of the interface that formed. The incorporation of coupling agents enhanced the resistance to deformation of the composite. The behavior of IA‐modified PP as a coupling agent was similar to that of a commercial MA‐modified PP for the filled PP composites. Evidence of improved interfacial bonding was revealed by scanning electron microscopy studies, which examined the surfaces of fractured tensile test specimens; their microstructures confirmed the mechanical results with respect to the observed homogeneous or optimized dispersion of the mineral‐filler phase in these composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2343–2350, 2007     

Thermal and mechanical behavior of poly(vinyl butyral)‐modified novolac epoxy/multiwalled carbon nanotube nanocomposites

The effects of poly(vinyl butyral) (PVB) and acid‐functionalized multiwalled carbon nanotube modification on the thermal and mechanical properties of novolac epoxy nanocomposites were investigated. The nanocomposite containing 1.5 wt % PVB and 0.1 wt % functionalized carbon nanotubes showed an increment of about 15°C in the peak degradation temperature compared to the neat novolac epoxy. The glass‐transition temperature of the novolac epoxy decreased with increasing PVB content but increased with an increase in the functionalized carbon nanotube concentration. The nanocomposites showed a lower tensile strength compared to the neat novolac epoxy; however, the elongation at break improved gradually with increasing PVB content. Maximum elongation and impact strength values of 7.4% and 17.0 kJ/m² were achieved in the nanocomposite containing 1.5 wt % PVB and 0.25 wt % functionalized carbon nanotubes. The fractured surface morphology was examined with field emission scanning electron microscopy, and correlated with the mechanical properties. The functionalized carbon nanotubes showed preferential accumulation in the PVB phase beyond 0.25 wt % loading. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43333.