Microstructural characteristics of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Microstructural characteristics of isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA) showed that the iPP/SEBS and iPP/SEBS‐g‐MA blends were partially compatible two‐phase systems. Well‐dispersed spherical GB and acicular W particles without evidence of interfacial adhesion were observed in the iPP/GB and iPP/W binary composites respectively. Contrary to the blends, melt flow rates of the iPP/GB and PP/W composites decreased more with SEBS‐g‐MA than with SEBS because of enhanced interfacial adhesion with SEBS‐g‐MA elastomer. The SEM analyses showed that the ternary composites containing SEBS exhibited separate dispersion of the rigid filler and elastomer particles (i.e., separate microstructure). However, SEBS‐g‐MA elastomer not only encapsulated the spherical GB and acicular W particles completely with strong interfacial adhesion (i.e., core‐shell microstructure) but also dispersed separately throughout iPP matrix. In accordance with the SEM observations, the DSC and DMA revealed quantitatively that the rigid filler and SEBS particles in iPP matrix acted individually, whereas the rigid filler particles in the ternary composites containing SEBS‐g‐MA acted like elastomer particles because of the thick elastomer interlayer around the filler particles. The Fourier transform infrared analyses revealed an esterification reaction inducing the strong interfacial adhesion between the SEBS‐g‐MA phase and the filler particles. POLYM. COMPOS., 31:1265–1284, 2010. © 2009 Society of Plastics Engineers     

Use of silanes and copolymers as adhesion promoters in glass fiber/polyethylene composites

Two organofunctional silanes and three functionalized copolymers were used as adhesion promoters in glass fiber/polyethylene‐reinforced composites. The performance of the coupling agents was investigated by mechanical property measurements, scanning electron microscopy, and dynamic mechanical analysis. Coupling achieved with the poly(ethylene‐g‐maleic anhydride) copolymer proved to be the most successful compared with the other copolymers (ethylene/vinyl alcohol, ethylene/acrylic acid) and silane agents (γ‐methacryloxypropyltrimethoxy, cationic styryl). The combined coupling performance of the silanes and copolymers examined in this study appears to be controlled by the coupling performance of the copolymer. Effective coupling was reflected in increased mechanical properties. Increased fiber/matrix adhesion is not always associated with effective coupling because structural changes occurring at the interface region can result in a deterioration of the material property. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2877–2888, 2001     

Preparation and performance characteristics of short‐glass‐fiber/maleated styrene–ethylene–butylene–styrene/polypropylene hybrid composites

Eighty/twenty polypropylene (PP)/styrene–ethylene–butylene–styrene (SEBS) and 80/20 PP/maleated styrene–ethylene–butylene–styrene (SEBS‐g‐MA) blends reinforced with 30 wt % short glass fibers (SGFs) were prepared by extrusion and subsequent injection molding. The influence of the maleic anhydride (MA) functional group grafted to SEBS on the properties of SGF/SEBS/PP hybrid composites was studied. Tensile and impact tests showed that the SEBS‐g‐MA copolymer improved the yield strength and impact toughness of the hybrid composites. Extensive plastic deformation occurred at the matrix interface layer next to the fibers of the SGF/SEBS‐g‐MA/PP composites during impact testing. This was attributed to the MA functional group, which enhanced the adhesion between SEBS and SGF. Differential scanning calorimetry measurements indicated that SEBS promoted the crystallization of PP spherulites by acting as active nucleation sites. However, the MA functional group grafted to SEBS retarded the crystallization of PP. Finally, polarized optical microscopy observations confirmed the absence of transcrystallinity at the glass‐fiber surfaces of both SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrid composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1303–1311, 2002     

Rheological behaviors of glass bead‐ and wollastonite‐filled polypropylene composites modified with thermoplastic elastomers

Steady‐ and oscillatory‐shear rheological behaviors of polypropylene/glass bead (PP/GB) and PP/wollastonite (PP/W) melts modified with thermoplastic elastomers, poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and the corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were examined by means of a parallel‐plate rheometer. With adding the elastomers (SEBS and SEBS‐g‐MA) and fillers (spherical GB and acicular W) to PP, viscosity especially at low shear rates and shear‐thinning flow behavior at high shear rates were pronounced as evidenced quantitatively by Carreau–Yasuda (CY) parameters, but Cox–Merz analogy became weakened. Besides, melt‐elasticity in terminal region and relaxation time (t_c) in crossing point increased, indicating an enhancement in quasi‐solid behavior of molten PP. Comparing with the elastomers, rheological behaviors of molten PP were more influenced with adding the rigid fillers, especially with W due to distinct acicular shape of W particles. SEBS‐g‐MA elastomer more affected rheological behaviors of the ternary composites than SEBS elastomer, implying that SEBS elastomer and the filler particles behaved individually (i.e., development of separate microstructure) in (PP/GB)/SEBS and (PP/W)/SEBS ternary composites, but core‐shell microstructure developed with strong interfacial adhesion by adding SEBS‐g‐MA elastomer, and the filler particles encapsulated with the thick SEBS‐g‐MA elastomer interlayer (i.e., core‐shell particles) acted like neither big elastomer particles nor like individual rigid particles in melt‐state. Moreover, effects of SEBS‐g‐MA elastomer reached a maximum on rheological behaviors of (PP/W)/SEBS‐g‐MA ternary composite, indicating a synergy between core‐shell microstructure and acicular W particles. Correlations between oscillatory‐shear flow properties and microstructures of the blends and composites were evaluated using Cole–Cole (CC), Han–Chuang (HC), and van Gurp–Palmen (vGP) plots. COMPOS., 2012. © 2012 Society of Plastics     

Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO₃ composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO₃, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO₃ particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO₃ particles. The crystallization and mechanical properties of PP/nano‐CaCO₃ composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO₃ particles, favored the nucleation effect of nano‐CaCO₃, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO₃ composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO₃, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of interfacial adhesion on properties of polypropylene/Wollastonite composites

Wollastonite reinforced polypropylene (PP/CaSiO₃) composites were prepared by melt extrusion. A silane coupling agent and a maleic anhydride grafted PP (PP‐g‐MA) were used to increase the interfacial adhesion between the filler and the matrix. The increased adhesion observed by scanning electron microscopy (SEM) resulted in improved mechanical properties. A model was applied to describe the relationship between the interfacial adhesion and tensile properties of PP/CaSiO₃ composites. There is stronger interfacial adhesion between silane‐treated CaSiO₃ and polymer matrix containing PP‐g‐MA as a modifier. Results of dynamic mechanical thermal analysis (DMTA) showed that stronger interfacial adhesion led to higher storage modulus. The influence of CaSiO₃ particles on the crystallization of PP was studied by using differential scanning calorimetry (DSC). The introduction of CaSiO₃ particles does not affect the crystallization temperature and crystallinity of PP matrix significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A compatibilized composite of recycled polypropylene filled with cellulosic fiber from recycled corrugated paper board: Mechanical properties,morphology, and thermal behavior

This article deals with the feasibility of using recycled corrugated paper board (rPF) as the reinforcing material for recycled plastics. The composites of recycled polypropylene (rPP) and rPF were prepared by extrusion compounding and injection molding, and the rPP/rPF composites compatibilized by maleic anhydride grafted PP (PP‐g‐MA), maleic anhydride grafted ethylene‐1‐octene copolymer (POE‐g‐MA), and maleic anhydride grafted styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA) were also prepared. The crystallization and melting behavior, mechanical properties, thermal stability, and morphology of these composites were studied. The results indicated that rPF promoted the crystallization, enhanced the strength and toughness of rPP/rPF composites to some extent while decreased thermal stability at the same time. PP‐g‐MA and POE‐g‐MA improved the dispersion and interface adhesion of rPF, and further upgraded the mechanical properties and vicat softening temperatures. Among these compatibilizers, PP‐g‐MA was most favorable to the strength improvement while POE‐g‐MA was most favorable to the toughness improvement. As for SEBS‐g‐MA, it had no obvious modification effect. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Process–structure–property relationship in ternary short‐glass‐fiber/elastomer/polypropylene composites

Short‐glass‐fiber (SGF)‐reinforced polypropylene (PP) composites toughened with a styrene/ethylene butylene/styrene (SEBS) triblock copolymer were injection molded after extrusion. Furthermore, a maleic anhydride (MA)‐grafted SEBS copolymer (SEBS‐g‐MA) was used as an impact modifier and compatibilizer. The effects of the processing conditions and compatibilizer on the microstructure and tensile and impact performance of the hybrid composites were investigated. In the route 1 fabrication process, SGF, PP, and SEBS were blended in an extruder twice, and this was followed by injection molding. In route 2, or the sequential blending process, the elastomer and PP were mixed thoroughly before the addition of SGF. In other words, either PP and SEBS or PP and SEBS‐g‐MA pellets were premixed in an extruder. The produced pellets were then blended with SGF in the extruder, and this was followed by injection molding. The SGF/SEBS‐g‐MA/PP hybrid fabricated by the route 2 process exhibited the highest modulus, yield stress, tensile stress at break, Izod impact energy, and Charpy drop weight impact strength among the composites investigated. This was due to the formation of a homogeneous SEBS elastomeric interlayer at the SGF and matrix interface of the SGF/SEBS‐g‐MA/PP hybrid. This SEBS rubbery layer enhanced the interfacial bonding between SGF and the matrix of the SGF/SEBS‐g‐MA/PP hybrid. The correlations between the processing, microstructure, and properties of the hybrids were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1384–1392, 2003     

Mechanical,thermal, and morphological properties of maleic anhydride‐g‐polypropylene compatibilized and chemically modified banana‐fiber‐reinforced polypropylene composites

Composites were prepared with chemically modified banana fibers in polypropylene (PP). The effects of 40‐mm fiber loading and resin modification on the physical, mechanical, thermal, and morphological properties of the composites were evaluated with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Infrared (IR) spectroscopy, and so on. Maleic anhydride grafted polypropylene (MA‐g‐PP) compatibilizer was used to improve the fiber‐matrix adhesion. SEM studies carried out on fractured specimens indicated poor dispersion in the unmodified fiber composites and improved adhesion and uniform dispersion in the treated composites. A fiber loading of 15 vol % in the treated composites was optimum, with maximum mechanical properties and thermal stability evident. The composite with 5% MA‐g‐PP concentration at a 15% fiber volume showed an 80% increase in impact strength, a 48% increase in flexural strength, a 125% increase in flexural modulus, a 33% increase in tensile strength, and an 82% increase in tensile modulus, whereas the heat deflection temperature increased by 18°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development and characterization of green composites from bio‐based polyethylene and peanut shell

In the present work, different compatibilizers, namely polyethylene‐graft‐maleic anhydride (PE‐g‐MA), polypropylene‐graft‐maleic anhydride (PP‐g‐MA), and polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene‐graft‐maleic anhydride (SEBS‐g‐MA) were used on green composites derived from biobased polyethylene and peanut shell (PNS) flour to improve particle–polymer interaction. Composites of high‐density polyethylene/peanut shell powder (HDPE/PNS) with 10 wt % PNS flour were compatibilized with 3 wt % of the abovementioned compatibilizers. As per the results, PP‐g‐MA copolymer lead to best optimized properties as evidenced by mechanical characterization. In addition, best particle–matrix interface interactions with PP‐g‐MA were observed by scanning electron microscopy (SEM). Subsequently HDPE/PNS composites with varying PNS flour content in the 5–30 wt % range with PP‐g‐MA compatibilizer were obtained by melt extrusion and compounding followed by injection molding and were characterized by mechanical, thermal, and morphological techniques. The results showed that PNS powder, leads to an increase in mechanical resistant properties (mainly, flexural modulus, and strength) while a decrease in mechanical ductile properties, that is, elongation at break and impact absorbed energy is observed with increasing PNS flour content. Furthermore, PNS flour provides an increase in thermal stability due to the natural antioxidant properties of PNS. In particular, composites containing 30 wt % PNS powder present a flexural strength 24% and a flexural modulus 72% higher than the unfilled polyethylene and the thermo‐oxidative onset degradation temperature is increased from 232 °C up to 254 °C thus indicating a marked thermal stabilization effect. Resultant composites can show a great deal of potential as base materials for wood plastic composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43940.     

Enhanced foamability of isotactic polypropylene composites by polypropylene‐graft‐carbon nanotube

In this article, utilizing a nucleophilic substitution reaction between epoxy group in polypropylene‐graft‐glycidyl methacrylate (PP‐g‐GMA) and carboxyl groups in oxidized carbon nanotubes (O‐CNTs), PP‐g‐CNT was fabricated for reinforcing the interfacial adhesion between CNTs and polypropylene (PP) matrix, favoring the enhancement of melt strength and elastic modulus, i.e., enhancing the foaming ability of PP composites. Cellular structure and thermo‐mechanical properties of PP foams were characterized by scanning electron microscopy and dynamic mechanical analysis, respectively. The average cell diameter of PP foams decreased from 289.2 (PP‐g‐GMA) to 96.7 μm (PP‐g‐CNT foams with 2.0 wt % O‐CNT) and the distribution of cell size also became more uniform. The storage modulus of PP‐g‐CNT foams increased by nearly 62.5% at ?40°C, compared with that of PP‐g‐GMA foams. This work also provided a new procedure for improving the foam ability and thermo‐mechanical property of PP composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 961‐968, 2013     

Study on poly(propylene)/ammonium polyphosphate composites modified by ethylene‐1‐octene copolymer grafted with glycidyl methacrylate

The compatibilization effect of ethylene‐1‐octene copolymer grafted with glycidyl methacrylate (POE‐g‐GMA) as an interface compatibilizer on the mechanical and combustion properties, and the morphology and structures of the cross sections of ammonium polyphosphate (APP)–filled poly(propylene) (PP) were investigated by thermogravimetry, dynamic mechanical analysis, and differential scanning calorimetry. The results indicated that the toughness of the PP/APP composites increased rapidly with adding POE‐g‐GMA; the dynamic mechanical spectra revealed that the increase of the toughness was closely related to the peaks of loss modulus (E″) and mechanical loss (tan δ). The improvement of the dispersion of APP in the PP matrix was attributed to the addition of POE‐g‐GMA; it was found that the interfacial adhesion between the filler and matrix was enhanced when the grafting material was added to the composites. Under such circumstances, the ratio of char formation was increased when the PP composites were heated, although the content of flame retardant was not changed, so the flame retardance of the material was improved. The addition of POE‐g‐GMA increased the rate of crystallization. At the same time, the degree of crystallinity and the temperature at the beginning of crystallization were decreased, although exerting little influence on the melt behavior of the crystallization of the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 412–419, 2004     

Mechanical properties of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Mechanical properties of the isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, the poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were investigated. An increase in toughness of iPP with the elastomers was associated with a decrease in rigidity and strength. Mechanical performance of iPP increased more with acicular W than with spherical GB due to reinforcing effect of W. Comparing the (iPP/GB)/SEBS and (iPP/W)/SEBS composites having the separate microstructure, strength and toughness values of the iPP/GB and iPP/W composites increased more with SEBS‐g‐MA at the expense of rigidity due to the core‐shell microstructure with strong interfacial adhesion. Moreover, the iPP/W composite exhibited superior mechanical performance with 2.5 and 5 vol% of SEBS‐g‐MA because of a positive synergy between the core‐shell microstructure and reinforcing effect of acicular W. The extended models revealed that the elastomer and filler particles in the (iPP/GB)/SEBS and (iPP/W)/SEBS composites acted individually due to the separate microstructure. However, the rigid GB and W particles encapsulated with the thick elastomer interlayer (R₀/R₁ = 0.91) in the (iPP/GB)/SEBS‐g‐MA and (iPP/W)/SEBS‐g‐MA composites acted like neither big elastomer particles nor like individual rigid particles, inferring more complicated failure mechanisms in the core‐shell composites. POLYM. COMPOS., 31:1285–1308, 2010. © 2010 Society of Plastics Engineers     

Evaluation of toughening mechanisms of polypropylene/ethylene–octene copolymer/maleic anhydride‐grafted poly(ethylene‐co‐octene)/clay nanocomposite

The toughness of a polypropylene (PP)/ethylene‐octene copolymer (EOC)/maleic anhydride‐grafted poly(ethylene‐co‐octene) (EOC‐g‐MA)/clay nanocomposite and blends of PP/EOC and PP/EOC/EOC‐g‐MA was investigated using Charpy impact and single‐edge‐notch tensile (SENT) tests. In order to understand the toughening mechanisms, impact fracture surfaces and damage zones of single‐edge‐notch samples were studied with scanning electron microscopy and transmission optical microscopy, respectively. It was observed that the addition of EOC‐g‐MA to PP/EOC blend led to improvements in both impact strength and fracture energy of SENT tests because of the enhanced compatibility of the blend, which resulted from reduced EOC particle size and improved interfacial adhesion, and the decreased crystallinity of PP. The incorporation of clay to PP/EOC/EOC‐g‐MA blend caused a further increase of the toughness, owing to the greater decrease in the size of elastomer particles, to the presence of clay tactoids inside the elastomer phase and presumably to debonding of clay layers during the low‐speed SENT tests. The results of microscopic observations showed that the main toughening mechanism in PP/EOC/EOC‐g‐MA blend and PP/EOC/EOC‐g‐MA/clay nanocomposite is crazing. Copyright © 2012 Society of Chemical Industry     

Study of dynamically cured PP/MAH‐g‐PP/talc/epoxy composites

In the present study, an epoxy resin was dynamically cured in a polypropylene (PP)/maleic anhydride–grafted PP (MAH‐g‐PP)/talc matrix to prepare dynamically cured PP/MAH‐g‐PP/talc/epoxy composites. An increase in the torque at equilibrium showed that epoxy resin in the PP/MAH‐g‐PP/talc composites had been cured by 2‐ethylene‐4‐methane‐imidazole. Scanning electron microscopy analysis showed that MAH‐g‐PP and an epoxy resin had effectively increased the interaction adhesion between PP and the talc in the PP/talc composites. Dynamic curing of the epoxy resin further increased the interaction adhesion. The dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had higher crystallization peaks than did the PP/talc composites. Thermogravimetric analysis showed that the addition of MAH‐g‐PP and the epoxy resin into the PP/talc composites caused an obvious improvement in the thermal stability. The dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had the best thermal stability of all the PP/talc composites. The PP/MAH‐g‐PP/talc/epoxy composites had better mechanical properties than did the PP/MAH‐g‐PP/talc composites, and the dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had the best mechanical properties of all the PP/talc composites, which can be attributed to the better interaction adhesion between the PP and the talc. The suitable content of epoxy resin in the composites was about 5 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Dynamic reaction inside co‐rotating twin screw extruder. II. Waste ground rubber tire powder/polypropylene blends

In this article, dynamic reaction of waste ground rubber tire powder/PP blends with compatibilizers is extended to commercially available waste rubber Viz. Ground rubber tire and PP for the possibility of getting recycled material with good mechanical properties. In the first part of the article it was shown that the compatibility of model material/PP blends has greatly improved. In this article, extensive studies have been carried out to study the effect of compatibilizers, in‐situ compatibilization of immiscible waste ground rubber tire (WGRT) powder/polyolefin blends of various concentrations was investigated by means of extrusion process using a co‐rotating twin screw extruder. It was observed that addition of small amounts of compatibilizers like SEBS‐g‐MA to the blends of WGRT and PP‐g‐MA can result in better mechanical properties than the blends with isotactic PP. The blends of WGRT powder and PP‐g‐MA with compatibilizer have better adhesion than those of isotactic PP blends as revealed by the morphological studies using AFM and SEM. The betterment in properties can be attributed to the presence of functional group, maleic anhydride in PP‐g‐MA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Morphology,Thermal Stability,and Mechanical Behavior of [Poly(propylene)‐grafted Maleic Anhydride]‐Layered Expanded Graphite Oxide Composites

PP‐g‐MA‐layered EGO composites were prepared directly by solution blending. Two types of PP‐g‐MA/EGO composites were prepared using different mixing methods: distributive and dispersive. In this study, the effects of the mixing method of EGO on the crystalline structure and thermo‐mechanical properties of PP‐g‐MA/EGO composites are reported. WAXD exhibited a shift in 2θ of the monoclinic (α) phase of PP‐g‐MA and (002) EGO peaks for PP‐g‐MA/EGO layered composites, which indicated a modification of the crystalline structure of PP‐g‐MA in the layered composites. DSC exhibited a single characteristic melting peak of monoclinic (α) crystalline phase PP‐g‐MA. The incorporation of EGO increased T_c indicating that the EGO acted as a nucleating agent for PP‐g‐MA. The crystallinity of the PP‐g‐MA/EGO composites was found to be dependent on the mixing method. Thermogravimetry demonstrated that PP‐g‐MA in the presence of EGO has higher degradation temperature, suggesting that the graphite particles acted as a thermal barrier material for PP‐g‐MA. DMA indicated that incorporation of EGO into PP‐g‐MA increased the storage modulus, due to the hydrogen bonding between EGO and MA of PP‐g‐MA.

     

Effect of maleic anhydride/vinyltrimethoxysilane‐co‐grafting polypropylene on the properties of wood‐flour/polypropylene composites by electron‐beam preirradiation

The electron‐beam preirradiation and reactive extrusion technologies were used to prepare maleic anhydride (MAH)/vinyltrimethoxysilane (VTMS)‐co‐grafting polypropylene (PP) as a high‐performance compatibilizer for wood‐flour/PP composites. The grafting content, chemical structure, and crystallization behavior of the compatibilizers were characterized through Fourier transform infrared spectroscopy, differential scanning calorimetry, and an extraction method. The effects of the compatibilizers on the mechanical properties, water absorption, morphological structure, and torque rheological behavior of the composites were investigated comparatively. The experimental results demonstrate that MAH/VTMS‐g‐PP markedly enhanced the mechanical properties of the composites. Compared with MAH‐g‐PP and VTMS‐g‐PP, MAH/VTMS‐g‐PP clearly showed synergistic effects on the increasing mechanical properties, water absorption, and compatibility of the composites. Scanning electron microscopy further confirmed that the adhesion and dispersion of wood flours in the composites were effectively improved by MAH/VTMS‐g‐PP. These results were also proven by the best water resistance of the wood‐flour/PP composites with MAH/VTMS‐g‐PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interfacial modification of single‐walled carbon nanotubes for high‐loading‐reinforced polypropylene composites

In this article, we present a strategy for fabricating polypropylene (PP)/polypropylene‐regrafted single‐walled carbon nanotube (PP‐re‐g‐SWNT) composites with a high loading of single‐walled carbon nanotubes (SWNTs; 20 wt %). The PP‐re‐g‐SWNTs were characterized by X‐ray photoelectron, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA). The PP‐re‐g‐SWNTs showed excellent interfacial adhesion and dispersion. Furthermore, PP molecules, about 72 wt % by mass, were homogeneously bonded onto the surface of the SWNTs according to TGA. In this hybrid nanocomposite system, the PP‐re‐g‐SWNTs were covalently integrated into the PP matrix and became part of the conjugated network structure (as evidenced by differential scanning calorimetry and dynamic mechanical analysis) rather than just a separate component. Accordingly, the PP/PP‐re‐g‐SWNT composites presented obvious improvements in mechanical properties and conductivity (from 10^?10 to 10^?2). Most importantly, the tensile and flexural strength of the PP/PP‐re‐g‐SWNT composites did not exhibit an obvious downturn with the addition of 20 wt % SWNTs; this was contrary to documented results. We believe that these new observations were due to the novel structure of the PP‐re‐g‐SWNTs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39817.     

Morphology and flame‐retardancy properties of ternary high‐impact polystyrene/elastomer/polystyrene‐encapsulated magnesium hydroxide composites

The effects of elastomer type on the morphology, flammability, and mechanical properties of high‐impact polystyrene (HIPS)/polystyrene (PS)‐encapsulated magnesium hydroxide (MH) were investigated. The ternary composites were characterized by cone calorimetry, mechanical testing, and scanning electron microscopy. Morphology was controlled with poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) triblock copolymer or the corresponding maleinated poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS‐g‐MA). The HIPS/SEBS/PS‐encapsulated MH composites exhibited separation of the filler and elastomer, whereas the HIPS/SEBS‐g‐MA/PS‐encapsulated MH composites exhibited encapsulation of the filler by SEBS‐g‐MA. The flame‐retardant and mechanical properties of the ternary composites were strongly dependent on microstructure. The composites with an encapsulation structure showed higher flame‐retardant properties than those with a separation structure at the optimum use level of SEBS‐g‐MA. Furthermore, the composites with a separation structure showed a higher modulus and impact strength than those with an encapsulation structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008