Effect of polyethylene‐graft‐maleic anhydride as a compatibilizer on the mechanical and tribological behaviors of ultrahigh‐molecular‐weight polyethylene/copper composites

Ultrahigh‐molecular‐weight polyethylene/copper (UHMWPE/Cu) composites compatibilized with polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) were prepared by compression molding. The effects of the compatibilizer on the mechanical, thermal, and tribological properties of the UHMWPE/Cu composites were investigated. These properties of the composites were evaluated at various compositions, and worn steel surfaces and composite surfaces were examined with scanning electron microscopy and X‐ray photoelectron spectroscopy. The incorporation of PE‐g‐MAH reduced the melting points of the composites and increased their crystallinity to some extent. Moreover, the inclusion of the PE‐g‐MAH compatibilizer greatly increased the tensile rupture strength and tensile modulus of the composites, and this improved the wear resistance of the composites. These improvements in the mechanical and tribological behavior of the ultrahigh‐molecular‐weight‐polyethylene‐matrix composites with the PE‐g‐MAH compatibilizer could be closely related to the enhanced crosslinking function of the composites in the presence of the compatibilizer. Moreover, the compatibilizer had an effect on the transfer and oxidation behavior of the filler Cu particulates, which could be critical to the application of metallic‐particulate‐filled polymer composites in engineering. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 948–955, 2004     

Simultaneously enhanced mechanical properties and thermal properties of ultrahigh‐molecular‐weight polyethylene with polydopamine‐coated α‐alumina platelets

Polydopamine (PDA) was employed to modify micrometric Al₂O₃ platelets to improve the interfacial compatibility between α‐Al₂O₃ powder and ultrahigh‐molecular‐weight polyethylene (UHMWPE). The structure of PDA‐coated Al₂O₃ and UHMWPE composites was investigated via Fourier transform infrared spectroscopy, scanning electron microscopy and X‐ray photoelectron spectroscopy. The thermal stability and mechanical performance of the samples were also evaluated. It is clear that UHMWPE/PDA‐Al₂O₃ composites exhibit better mechanical properties, higher thermal stability and higher thermal conductivity than UHMWPE/Al₂O₃ composites, owing to the good dispersion of Al₂O₃ powder in the UHMWPE matrix and the strong interfacial force between the macromolecules and the inorganic filler caused by the presence of PDA. The tensile strength and the tensile elongation at break of UHMWPE/PDA‐Al₂O₃ composite with 1 wt% PDA‐Al₂O₃ are 62.508 MPa and 462%, which are 1.96 and 1.98 times higher than those of pure UHMWPE, respectively. The thermal conductivity of UHMWPE/PDA‐Al₂O₃ composite increases from 0.38 to 0.52 W m^?1 K^?1 with an increase in the dosage of PDA‐Al₂O₃ to 20 wt%. The results show that the prepared PDA‐coated Al₂O₃ powder can simultaneously enhance the mechanical properties and thermal conductivity of UHMWPE. © 2018 Society of Chemical Industry     

Polyethylene‐block‐poly(ε‐caprolactone) diblock copolymers: synthesis and compatibility

A strategy is introduced for the synthesis of polyethylene‐block‐poly(ε‐caprolactone) block copolymers by a combination of coordination polymerization and ring‐opening polymerization. First, end‐hydroxylated polyethylene (PE‐OH) was prepared with a one‐step process through ethylene/3‐buten‐1‐ol copolymerization catalyzed by a vanadium(III) complex bearing a bidentate [N,O] ligand ([PhN?C(CH₃)CHC(Ph)O]VCl₂(THF)₂). The PE‐OH was then used as macroinitiator for ring‐opening polymerization of ε‐caprolactone, leading to the desired nonpolar/polar diblock copolymers. The block structure was confirmed by spectral analysis using ¹H NMR, gel permeation chromatography and differential scanning calorimetry. The unusual topologies of the model copolymers will establish a fundamental understanding for structure–property correlations, e.g. compatibilization, of polymer blends and surface and interface modification of other polymers. © 2014 Society of Chemical Industry     

Influences of the chain structure of PE‐b‐PEG on the properties of PE/PE‐b‐PEG blend membranes prepared by TIPS

In this article, a series of diblock copolymer polyethylene‐b‐ poly(ethylene glycol)s (PE‐b‐PEGs) with various molecular weight of polyethylene segment was blended with linear low‐density PE. The PE/PE‐b‐PEG blend porous membranes with high porosity were obtained by thermally induced phase separation (TIPS) process. The isothermal crystallization kinetics of PE/LP/PE‐b‐PEG blends indicated that the introduction of PE‐b‐PEG could inhibit the growth rate of polyethylene crystals which could increase the pore size and porosity of the membranes. The PE/PE‐b‐PEG blend membranes with PE₁₃₀₀‐b‐PEG₂₂₀₀ showed the largest pore size and porosity due to its crystallization behavior during TIPS. The surface of the membranes became smoother and the morphology of the membranes could be effectively tuned by introducing PE‐b‐PEG. Compared with the PE membrane, the PE/PE‐b‐PEG blend membranes exhibited higher hydrophilicity (the water contact angle decreased from 112° to 84°), water permeability (the permeation flux increased from 80 to 440 L/m² h under 0.1 MPa), rejection performance (completely reject carbon particles in the filtration of carbon ink solution), and fouling resistance (the value of protein adsorption dropped from 0.25 to 0.05 mg/cm²). The hydrophilicity and fouling resistance of PE/PE‐b‐PEG blend membranes increased as the length of PE segment in PE‐b‐PEGs decreased. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46499.     

Study on the rheological behaviors of UHMWPE/CA‐MMT nanocomposite

In our previous study, we have prepared a novel antibacterial ultra‐high molecular weight polyethylene/chlorhexidine acetate‐montmorillonoid (UHMWPE/CA‐MMT) composites and examined its crystallization process and kinetics [1]. In this work, the rheological behaviors of pure UHMWPE, UHMWPE/MMT, UHMWPE/CA, and UHMWPE/CA‐MMT were characterized. The results showed that MMT can increase the viscosity of the polymer composites and CA can act as a plasticizer in the composites. Compared with UHMWPE/CA, UHMWPE/CA‐MMT had lower η*, G′, and G″. The TGA result indicated that CA‐MMT has higher thermostability than CA. Hence, CA‐MMT has the lower thermal decomposition ratio at high temperature than CA when it is blended with polymer. The TGA result could be used to explain that UHMWPE/CA‐MMT composites had better plasticizer effect than UHMWPE/CA composites. POLYM. COMPOS., 36:47–50, 2015. © 2014 The Authors Polymer Composites published by Wiley Periodicals, Inc.     

Effect of silica nanopowder on the properties of wood flour/polymer composite

Low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), and polyvinyl chloride (PVC) (1:1:1:0.5) were solution blended by using a mixture of solvents consisting of xylene and tetrahydrofuran (THF) (70:30). SiO₂ nanoparticles were modified by cetyl trimethyl ammonium bromide (CTAB). Wood polymer composites (WPC) were prepared by using polymer mixture, polyethylene‐co‐glycidyl methacrylate (PE‐co‐GMA), wood flour, and modified SiO₂. X‐ray diffraction (XRD) studies showed that the intensity of the peaks of polymer mixture decreased due to incorporation of SiO₂. The dispersion of SiO₂ nanoparticles and morphological characteristics were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The interaction between SiO₂ nanoparticles, PE‐co‐GMA, polymer mixture, and wood was studied by Fourier transform infrared spectroscopy (FTIR). Tensile and flexural properties of the composites improved significantly due to the incorporation of SiO₂ nanoparticles. Thermal stability, hardness, flame retardancy, and water resistance capacity were also found to enhance. Maximum improvement in properties was observed by the inclusion of 3 phr modified SiO₂ in WPC. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

High‐performance printable paper‐like composites derived from plastic flexible film wastes

Owing to lack of proper recycling methods, plastic flexible film wastes are usually directly discarded or incinerated, which brings about severe environmental pollution. Therefore, converting plastic wastes into value‐added products has received more and more attention in recent years. In this work, paper‐like composites derived from plastic flexible film wastes were prepared via the thermally induced phase separation method by adding polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) as a compatibilizer and fumed silica as an additive. The resulting paper‐like composites were characterized by SEM and infrared spectroscopy. Other properties such as mechanical properties, thermal properties, whiteness, printability and adsorption performance were also tested in detail. It was found that remarkable enhancements in mechanical, thermal and printable properties of the paper‐like composites were obtained when nano‐SiO₂ loading was 2.5–3 wt%. Uniformly distributed holes that can endow good printability by providing space for ink or other functional molecules were observed by using SEM. Furthermore, the CIE whiteness value of the resulting composites can reach 91.6%–96.7% on adding nano‐SiO₂. Additionally, the paper‐like composites integrating nano‐SiO₂ and PE‐g‐MAH exhibited good solid ink affinity and high water or oil adsorption capacity. Thus, according to this research, high‐performance printable paper‐like composites used as major components of multifunctional papers can be prepared based on plastic flexible film wastes. © 2019 Society of Chemical Industry     

Polyaniline nanofibers for In situ MAO‐catalyzed polymerization of ethylene

In this work electro‐conductive polyaniline nanofibers (PAni‐nanofibers) were prepared via interfacial methodology. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the synthesized PAni‐nanofibers present high aspect ratio with an average diameter of 80 nm, while they exhibit high conductivity (DC conductivity values: 4.19 ± 0.21 S cm^?1). After specific treatment to remove moisture and remaining trapped HCl from PAni‐nanofibers, it was possible to prepare promising polyethylene (PE)/PAni composites by in situ polymerization of ethylene using bis(cyclopentadienyl) zirconium(IV) dichloride (Cp₂ZrCl₂) and methylaluminoxane (MAO) as catalytic system. More precisely, various contents of PAni‐nanofibers (from 0.2 to 7 wt %) were successfully incorporated in the in situ produced PE/PAni nanocomposites. PAni‐nanofibers were found to affect significantly the crystallization of the polyolefinic matrix while preserving its thermal stability. Preliminary measurements of electric properties showed PAni‐nanofibres are able to bring electro‐conductive properties to the in situ polymerized PE/PAni composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41197.     

Processing–Nanostructure–Property Relationships of All‐Polyethylene Composites Reinforced by Flow‐Induced Oriented Crystallization of UHMWPE

All‐polyethylene composites exhibiting substantially improved toughness/stiffness balance are readily produced during conventional injection molding of high density polyethylene (HDPE) in the presence of bimodal polyethylene reactor blends (RB40) containing 40 wt% ultrahigh molar mass polyethylene (UHMWPE) dispersed in HDPE wax. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses shows that flow‐induced crystallization affords extended‐chain UHMWPE nanofibers forming shish which nucleates HDPE crystallization producing shish‐kebab structures as reinforcing phases. This is unparalleled by melt compounding micron‐sized UHMWPE. Injection molding of HDPE with 30 wt% RB40 at 165 °C affords thermoplastic all‐PE composites (12 wt% UHMWPE), improved Young's modulus of 3400 MPa, tensile strength of 140 MPa, and impact resistance of 22.0 kJ/m². According to fracture surface analysis, the formation of skin‐intermediate‐core structures accounts for significantly improved impact resistance. At constant RB40 content both morphology and mechanical properties strongly depend upon processing temperature. Upon increasing processing temperature from 165 °C to 250 °C the average shish‐kebab diameter increases from the nanometer to micron range, paralleled by massive loss of self‐reinforcement above 200 °C. The absence of shish‐kebab structure at 250 °C is attributed to relaxation of polymer chains and stretch‐coil transition impairing shish formation.     

Syntheses of an azo‐group‐bound silica initiator and silica–polystyrene composites

In this article, we present a facile method for the synthesis of an azo‐group‐bound silica (SiO₂–azo) initiator. The azo groups were introduced onto the surface of silica (SiO₂) nanoparticles via facile condensation between 4,4′‐azobis‐4‐cyanopentanoic acid and the alkyl–hydroxyl groups ‐ immobilized on the SiO₂ nanoparticle surface under ambient conditions. The polystyrene (PS) chains were grafted onto the SiO₂ nanoparticle surface by in situ polymerization with the resulting SiO₂–azo as an initiator, and then, the SiO₂–PS composite was prepared. The syntheses and properties of the SiO₂–azo initiator and the composite were characterized by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, gel permeation chromatography, and differential scanning calorimetry techniques. The results confirm that the SiO₂–azo initiator and the composite were synthesized successfully. Styrene was polymerized with the initiation of SiO₂–azo, and the resulting PS domain accounted for 48.6% of the total amount of composite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Silica/polystyrene and silica/polystyrene‐b‐polymethacryloxypropyltrimethoxysilane hybrid nanoparticles via surface‐initiated ATRP and comparison of their wettabilities

Both silica/polystyrene (SiO₂/PS) and silica/polystyrene‐b‐polymethacryloxypropyltrimethoxysilane (SiO₂/PS‐b‐PMPTS) hybrid nanoparticles were synthesized via surface‐initiated atom transfer radical polymerization (SI‐ATRP) from SiO₂ nanoparticles. The growths of all polymers via ATRP from the SiO₂ surfaces were well controlled as demonstrated by the macromolecular characteristics of the grafted chains. Their wettabilities were measured and compared by water contact angle (WCA) and surface roughness. The results show that the nanoparticles possess hydrophobic surface properties. The static WCA of SiO₂/PS‐b‐PMPTS hybrid nanoparticles is smaller than that of SiO₂/PS hybrid nanoparticles, meanwhile, the surface roughness of SiO₂/PS‐b‐PMPTS hybrid nanoparticles is yet slightly rougher than that of SiO₂/PS hybrid nanoparticles, which shows that the combination and competition of surface chemistry and roughness of a solid material can finally determine its wettability. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Surface modification of ultra‐high molecular weight polyethylene fiber by different kinds of SiO2 nanoparticles

We successfully improved the interfacial adhesion strength between ultra‐high molecular weight polyethylene (UHMWPE) fiber and resin by the surface modification of UHMWPE fiber with two kinds of SiO₂ nanoparticles through gel spinning process. Modified effect of treated SiO₂ nanoparticles by coupling agent was superior to original SiO₂ nanoparticles. Compared with unmodified fibers, pull‐out tests of modified UHMWPE/treated SiO₂ fibers revealed that interfacial adhesion strength increased by the maximum of 10.95%, but corresponding breaking strength decreased by 8.51%. In addition, the interfacial adhesion strength and breaking strength could continue to enhance with increasing the additive amount of treated SiO₂ nanoparticles. The results of Differential Scanning Calorimetry (DSC), X‐ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) indicated that the crystallinity of all modified fibers decreased while crystallite dimension increased, and the surface of modified fibers by treated SiO₂ nanoparticles exhibited polar functional group (C=O). The superiority of this modified technology was that it realized the bulk industrial production and maneuverability, low cost, and no pollution. POLYM. COMPOS., 38:1928–1936, 2017. © 2015 Society of Plastics Engineers     

Organic/inorganic support for immobilizing (n‐BuCp)2ZrCl2/TiCl3 hybrid catalyst for use in the preparation of polymer blends

Reactor blends of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and low‐molecular‐weight polyethylene (LMWPE) were synthesized by two‐step polymerization using a hybrid catalyst. To prepare the hybrid catalyst, styrene acrylic copolymer (PSA) was first coated onto SiO₂/MgCl₂‐supported TiCl₃; then, (n‐BuCp)₂ZrCl₂ was immobilized onto the exterior PSA. UHMWPE was produced in the first polymerization stage with the presence of 1‐hexene and modified methylaluminoxane (MMAO), and the LMWPE was prepared with the presence of hydrogen and triethylaluminium in the second polymerization stage. The activity of the hybrid catalyst was considerable (6.5 × 10⁶ g PE (mol Zr)^?1 h^?1), and was maintained for longer than 8 h during the two‐step polymerization. The barrier property of PSA to the co‐catalyst was verified using ethylene polymerization experiments. The appearance of a lag phase in the kinetic curve during the first‐stage polymerization implied that the exterior catalyst ((n‐BuCp)₂ZrCl₂) could be activated prior to the interior catalyst (M‐1). Furthermore, the melting temperature, crystallinity, degree of branching, molecular weight and molecular‐weight distribution of polyethylene obtained at various polymerization times showed that the M‐1 catalyst began to be activated by MMAO after 40 min of the reaction. The activation of M‐1 catalyst led to a decrease in the molecular weight of UHMWPE. Finally, the thermal behaviors of polyethylene blends were investigated using differential scanning calorimetry. Copyright © 2011 Society of Chemical Industry     

Friction and wear properties of graphene oxide/ultrahigh‐molecular‐weight polyethylene composites under the lubrication of deionized water and normal saline solution

Ultrahigh‐molecular‐weight polyethylene (UHMWPE) and UHMWPE composites reinforced with graphene oxide (GO) were successfully fabricated through a new step of liquid‐phase ultrasonic dispersion, high‐speed ball‐mill mixing, and hot‐pressing molding technology. When the GO/UHMWPE composites were lubricated with deionized water (DW) and normal saline (NS) solution, their friction and wear properties were investigated through sliding against ZrO₂. The worn surface and wear volume losses of these composites were studied with scanning electron microscopy, X‐ray photoelectron spectroscopy, and a Micro‐XAM 3D non‐contact surface profiler. The results show that the microhardness of the GO/UHMWPE composites was improved by 13.80% and the wear rates were decreased by 19.86 and 21.13%, whereas the depths of the scratches were decreased by 22.93 and 23.77% in DW and NS lubricating conditions, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39640.     

Solid‐phase preparation method of silica‐supported 2,2′‐methylenebis(6‐tert‐butyl‐4‐methyl‐phenol) and its antioxidative behavior in styrene‐butadiene rubber

A solid‐phase preparation method is applied to the synthesis of a novel supported rubber antioxidant, silica–supported 2,2′‐methylenebis(6‐tert‐butyl‐4‐methyl‐phenol) (SiO₂‐2246), by directly reacting 2,2′‐methylenebis (6‐tert‐butyl‐4‐methyl‐phenol)(antioxidant 2246) with silica. FTIR, Raman spectroscopy and TGA confirm that the antioxidant 2246 is chemically bonded on the surface of the silica particles. The SEM observation shows that the SiO₂‐2246 is homogeneously dispersed in the styrene‐butadiene rubber (SBR) matrix. The results of the apparent activation energy and the attenuated total reflectance infrared spectrometry indicate that the antioxidative efficiency of the SiO₂‐2246 in SBR is superior to the corresponding low‐molecular‐weight 2246. The thermal oxidative stability of the SBR/SiO₂‐2246 composites is much higher than that of the SBR/SiO₂/2246 composites by comparing their mechanical properties retentions and crosslinking densities. Additionally, the advantages of SiO₂‐2246 also include low migration, low volatility, and low pollution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43014.     

Antibacterial activity and antistatic composites of polyester/Ag‐SiO2 prepared by a sol–gel method

Poly(butylene adipate‐co‐terephthalate) (PBAT) composites containing silver‐silica (Ag‐SiO₂) were prepared using an in‐situ sol–gel process. Maleic anhydride‐grafted PBAT (PBAT‐g‐MA) and multihydroxyl‐functionalized Ag‐SiO₂ were used to improve the compatibility and dispersibility of Ag‐SiO₂ within the PBAT matrix. The composites were characterized morphologically using transmission electron microscopy and chemically using Fourier transform infrared spectrometry. The existence of Ag‐SiO₂ nanoparticles on the substrate was confirmed by the ultraviolet–visible absorption spectra. The antibacterial and antistatic properties of the composites were evaluated whether SiO₂ enhanced the electrical conductivity was tested as well as whether Ag enhanced the antibacterial activity of the PBAT‐g‐MA/SiO₂ or PBAT/SiO₂ composites. The PBAT‐g‐MA/SiO₂ or PBAT/SiO₂ composite that contained Ag had better antibacterial activity (more than 1.3‐fold). The functionalized PBAT‐g‐MA/Ag‐SiO₂ composite can markedly enhanced antibacterial and antistatic properties due to the carboxyl groups of maleic anhydride, which acted as coordination sites for the Ag‐SiO₂ phase, allowing the formation of stronger chemical bonds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Epoxy resin/phosphorus‐based microcapsules: Their synergistic effect on flame retardation properties of high‐density polyethylene/graphene nanoplatelets composites

Two types of microcapsule flame retardants are prepared by coating ammonium polyphosphate (APP) and aluminum diethylphosphinate (ADP) with epoxy resin (EP) as the shell via in situ polymerization, and blended with high density polyethylene (HDPE)/graphene nanoplatelets (GNPs) composites to obtain flame‐retardant HDPE materials. Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water contact angle results confirm the formation of core–shell structures of EP@APP and EP@ADP. The limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimetry, and Raman spectroscopy are employed to characterize the HDPE/GNPs composites filled with EP@APP and EP@ADP core–shell materials. A UL94 V‐0 level and LOI of 34% is achieved, and the two flame retardants incorporated in the HDPE/GNPs composite at 20 wt % in total play a synergistic effect in the flame retardancy of the composite at a mass ratio of EP@ADP:EP@APP = 2:1. According to the cone‐calorimetric data, the compounding composites present much lower peak heat release rate (300 kW/m²) and total heat release (99.4 MJ/m²) than those of pure HDPE. Raman spectroscopic analysis of the composites after combustion reveals that the degree of graphitization of the residual char can reach 2.31, indicating the remarkable flame retarding property of the composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46662.     

Compression‐molded,lubricant‐treated UHMWPE composites

Lubricant‐treated ultra high molecular weight polyethylene (UHMWPE) composites were prepared by compression molding. Composites were made from mixtures containing up to 5.0 wt % of lubricant. Two solid lubricants, molybdenum disulfide (MoS₂), and carbon black (CB), and one liquid lubricant, perfluoropolyether (PFPE), were used in the study. UHMWPE and the lubricants formed 3D networks, where the lubricant was evenly spread over the UHMWPE particles. The amounts of MoS₂ and CB were determined by thermogravimetric analyses, and the amounts of PFPE by ATR‐IR spectroscopy. All the lubricant treated composites showed better friction properties than pure UHMWPE. The addition of PFPE to UHMWPE improved the hydrophobicity of the surface, whereas the addition of solid lubricant had little effect. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1762–1768, 2007     

Effect of vapor‐grown carbon nanofibers and in situ hydrolyzed silica on the mechanical and shape memory properties of water‐borne epoxy composites

Vapor‐grown carbon nanofiber (VGCNF)/water‐borne epoxy (WEP) and SiO₂/WEP composites were successfully synthesized via freeze drying and hot‐press molding. VGCNFs were mixed directly with a WEP emulsion, while SiO₂ was synthesized by in situ hydrolysis of TEOS solution (3‐triethoxysilylpropylamine (KH550): tetraethoxysilane (TEOS): absolute ethanol = 1:5:20, w/w/w) dispersed in the WEP emulsion. WEP composites were obtained from these mixtures by freeze drying and compressing under a pressure of 10 MPa at 120°C for 2 h. The morphology and mechanical properties of the WEP composites were investigated by transmission electron microscopy, scanning electron microscopy, dynamic mechanical analysis and tensile testing. The shape memory (SM) properties of the WEP composites were evaluated by fold‐deploy SM testing. The effects of filler content and recovery temperature on the SM properties were revealed through systematic variation. The results confirmed that VGCNF and in situ hydrolyzed SiO₂ were homogenously dispersed and incorporated into the WEP matrices. Thus, significant improvements in the mechanical and SM properties of the composites were achieved. POLYM. COMPOS., 36:1712–1720, 2015. © 2014 Society of Plastics Engineers