Polyethylene‐supported N‐bromosuccinimide polymeric reagent for use in some oxidation reactions

We report a three‐step preparation of a polymer‐supported oxidizing reagent, polyethylene‐g‐N‐bromosuccinimide (PE‐g‐NBS), through the graft copolymerization of maleic anhydride (MAn) onto polyethylene (PE) by a photochemical method with 1% benzophenone as a photosensitizer. The postgrafting treatment of polyethylene‐g‐maleic anhydride (PE‐g‐MAn) with urea on fusion gives polyethylene‐g‐succinimide (PE‐g‐succinimide), which, on further treatment with an aqueous solution of sodium hydroxide and bromine, gives the required reagent, PE‐g‐NBS. The maximum percentage grafting (25%) was obtained with 3.57 mol of MAn and 0.5 mL of 1% benzophenone in 120 min. Fourier transform infrared spectroscopy and thermogravimetric analysis methods were used to characterize the graft copolymer PE‐g‐MAn, PE‐g‐succinimide, and the polymeric support, that is, PE‐g‐NBS. The grafted PE and the polymeric support were found to be thermally stable. The polymer‐supported N‐bromosuccinimide was used successfully for the efficient oxidation of a series of alcohols, including 2‐propanol, n‐butanol, ethylene glycol, cyclohexanol, poly(vinyl alcohol), benzoin, benzyl alcohol, and chloromycetin, to their corresponding aldehydes and ketones. The selectivity of PE‐g‐NBS toward the oxidation of secondary alcoholic groups without the disturbance of the primary alcoholic groups was reflected during the oxidation of chloromycetin. The oxidized products were characterized by Fourier transform infrared and ¹H‐NMR spectral methods. The reagent was reused for the oxidation of fresh alcohols, and it was found to oxidize them successfully, although with a little lower product yield. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of 3‐aminopropyltriethoxysilane on properties of poly(butyl acrylate‐co‐maleic anhydride)/silica hybrid materials

The transparent poly(butyl acrylate‐co‐maleic anhydride)/silica [P(BA‐co‐MAn)/SiO₂] has been successfully prepared from butyl acrylate‐maleic anhydride copolymer P(BA‐co‐MAn) and tetraethoxysilane (TEOS) in the presence of 3‐aminopropyltriethoxysilane (APTES) by an in situ sol–gel process. Triethoxysilyl group can be readily incorporated into P(BA‐co‐MAn) as pendant side chains by the aminolysis of maleic anhydride unit of copolymer with APTES, and then organic polymer/silica hybrid materials with covalent bonds between two phases can be formed via the hydrolytic polycondensation of triethoxysilyl group‐functionalized polymer with TEOS. It was found that the amount of APTES could dramatically affect the gel time of sol–gel system, the sol fraction of resultant hybrid materials, and the thermal properties of hybrid materials obtained. The decomposition temperature of hybrid materials and the final residual weight of thermogravimetry of hybrid both increase with the increasing of APTES. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the morphology of hybrid materials prepared in the presence of APTES was a co‐continual phase structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 419–424, 1999     

Tri‐ammonium end functional polyethylene: facile synthesis and application as an intercalation agent

Organo‐modification of montmorillonite (MMT) is crucial for the promotion of a fine dispersion of MMT into an (often hydrophobic) polymer matrix. Ammonium‐terminated polymers are more efficient in modifying clay compared to small organic cations such as alkyl ammoniums or side functionalized polymers. Herein, tri‐amino end functional polyethylene (PE‐3 N) with low molecular weight was first synthesized via an efficient and robust epoxide ring‐opening reaction by treating epoxide‐terminated PE with diethylenetriamine. The chemical structure of PE‐3 N was unambitiously characterized by chromatographic and spectral methods. By reacting with excess HCl, PE‐3 N was subsequently converted to tri‐ammonium end functional polyethylene (PE‐3 N⁺), which serves as an intercalation agent of MMT. By adjusting the weight ratio of PE‐3 N⁺ to pristine MMT (R_P/M) applied in the static melt intercalation process, correlations between the extent of exfoliation and R_P/M were successfully established. XRD results revealed that complete exfoliation of MMT could be afforded with R_P/M as low as 1, which is the lowest value ever reported for ammonium‐terminated polymers applied as intercalation agents. SEM micrographs showed that MMT sheets were swollen by PE‐3 N⁺, affirming the successful modification of MMT. The PE modified MMT obtained may find application in preparing high‐performance PE/MMT nanocomposites. © 2017 Society of Chemical Industry     

Synergistic compatibilization and reinforcement of HDPE/wood flour composites

Multi‐monomer grafted copolymers, high‐density polyethylene‐grafted‐maleic anhydride‐styrene (HDPE‐g‐(MAH‐St)) and polyethylene wax‐grafted‐ maleic anhydride ((PE wax)‐g‐MAH), were synthesized and applied to prepare high‐performance high‐density polyethylene (HDPE)/wood flour (WF) composites. Interfacial synergistic compatibilization was studied via the coordinated blending of high‐density polyethylene‐grafted‐maleic anhydride (MPE‐St) and polyethylene wax‐grafted‐ maleic anhydride (MPW) in the high‐density polyethylene (HDPE)/wood flour (WF) composites. Scanning electron microscopy (SEM) morphology and three‐dimensional WF sketch presented that strong interactive interface between HDPE and WF, formed by MPE‐St with high graft degree of maleic anhydride (MAH) together with the permeating effect of MPW with a low molecular weight. Experimental results demonstrated that HDPE/WF composites compatibilized by MPE‐St/MPW compounds showed significant improvement in mechanical properties, rheological properties, and water resistance than those compatibilized by MPE, MPE‐St or MPW separately and the uncompatibilized composites. The mass ratio of MPE‐St/MPW for optimizing the HDPE/WF composites was 5:1. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42958.     

Effect of Al2O3 fibers on the thermal conductivity and mechanical properties of high density polyethylene with the absence and presence of compatibilizer

Alumina (Al₂O₃) fiber/high density polyethylene (HDPE) composites were prepared by molding injection with or without compatibilizer, in which, maleic anhydride‐grafted polyethylene (PE‐g‐MA) and acrylic acid‐grafted polyethylene (PE‐g‐AA) were used as the compatibilizers. The thermal conductivities of the composites were anisotropic and the conductivities in the injection direction of the samples were higher than those in perpendicular direction of the injection. The anisotropic thermal conductivity for Al₂O₃/PE‐g‐AA/HDPE was the most obvious and this composite also gave the best mechanical performance. The SEM and DMA test revealed that PE‐g‐AA was more effective than PE‐g‐MA in improving the matrix–filler interaction. The high interfacial interaction was more favorable for the viscous flow‐induced fiber orientation, which resulted in the largest anisotropic degree of thermal conductivity of the Al₂O₃/PE‐g‐AA/HDPE among the studied composite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Compatibilizer in waste tire powder and low‐density polyethylene blends and the blends modified asphalt

With the increasing ratio of waste tire powder (WTP) to low‐density polyethylene (LDPE), the hardness and tensile strength of the WTP/LDPE blends decreased while the elongation at break increased. Five kinds of compatibilizers, such as maleic anhydride‐grafted polyethylene (PE‐g‐MA), maleic anhydride‐grafted ethylene‐octene copolymer (POE‐g‐MA), maleic anhydride‐grafted linear LDPE, maleic anhydride‐grafted ethylene vinyl‐acetate copolymer, and maleic anhydride‐grafted styrene‐ethylene‐butylene‐styrene, were incorporated to prepare WTP/LDPE blends, respectively. PE‐g‐MA and POE‐g‐MA reinforced the tensile stress and toughness of the blends. The toughness value of POE‐g‐MA incorporating blends was the highest, reached to 2032.3 MJ/m³, while that of the control was only 1402.9 MJ/m³. Therefore, POE‐g‐MA was selected as asphalt modifier. The toughness value reached to the highest level when the content of POE‐g‐MA was about 8%. Besides that the softening point of the modified asphalt would be higher than 60°C, whereas the content of WTP/LDPE blend was more than 5%, and the blends were mixed by stirring under the shearing speed of 3000 rpm for 20 min. Especially, when the blend content was 8.5%, the softening point arrived at 82°C, contributing to asphalt strength and elastic properties in a wide range of temperature. In addition, the swelling property of POE‐g‐MA/WTP/LDPE blend was better than that of the other compalibitizers, which indicated that POE‐g‐MA /WTP/LDPE blend was much compatible with asphalt. Also, the excellent compatibility would result in the good mechanical and processing properties of the modified asphalt. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Diamine coupling of maleic‐anhydride‐ modified polyethylene

The efficiency of the diamines 1,12‐diaminododecane (C₁₂N₂) and (4,4′‐methylene)bis(2,6‐diethylaniline) (MDEA) used as coupling agents for maleic‐anhydride‐grafted polyethylene (PEgMA) was compared. The effect of the miscibility of the diamines on the course of the reaction with PEgMA was investigated. The reaction in the molten state with the functional PE was run at 150 °C in an internal mixer and the resulting modified PE was characterized. The coupling agents reacted very fast, especially the aliphatic diamine. The MDEA was slower. Moreover, the reaction of the latter with the anhydride functions was not total owing to its immiscibility with PEgMA. With C₁₂N₂, the NH₂‐to‐anhydride‐function stoichiometry leading to the higher degree of coupling was 2, indicating that the imide ring was not formed at this temperature. In this case, the coupling of the PEgMA chains resulted in a highly branched structure characterized by a high viscosity of the molten polymer and a substantial insoluble PE‐rich fraction. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of alkali‐modified styrene‐maleic anhydride copolymer for dispersion of TiO2

A copolymer of styrene and maleic anhydride was synthesized by free radical polymerization at 80°C using N,N‐dimethylformamide (DMF) as solvent and benzoylperoxide as initiator. The monomer feed ratio of styrene to maleic anhydride was varied in the range of 1 : 1 : to 3 : 1. The polymer yield was found to decrease with increase in styrene in the feed. The molecular weight of copolymers which were formed by taking styrene to maleic anhydride ratio of 1 : 1, 2 : 1, and 3 : 1, as determined by Ostwald Viscometery were about 1862, 2015, and 2276 respectively. The acid values of abovementioned three copolymers were found to be 480, 357, and 295, respectively. The typical viscosity values of 20% solids in ammonical solution of copolymers formed by taking feed ratios of Sty : MAn as 1 : 1 and 2 : 1 were 26 and 136 cp, respectively. For the feed ratio 3 : 1, a gel was formed. The synthesized copolymers were hydrolyzed by alkalis, namely, NaOH, KOH, and NH₄OH. The dispersing ability of hydrolyzed styrene‐maleic anhydride (SMA) copolymers for dispersion of titanium dioxide was studied. The modified SMA copolymers were found to be effective dispersants for TiO₂. Among the three alkalis studied, the Sodium salts of SMA were found to give better dispersion. The copolymer having a 1 : 1 feed ratio showed the best dispersing ability for TiO₂ particles among the three ratios studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3194–3205, 2007     

Polysulfobetaines and corresponding cationic polymers. VI. Synthesis and aqueous solution properties of cationic poly(methyl iodide quaternized acrylamide–N,N-dimethylaminopropylmaleimide copolymer) [poly(MIQADMAPM)]

The copolymer prepared by copolymerizing with acrylamide and maleic anhydride was imidized with N,N-dimethylaminopropylamine. The obtained acrylamide–N,N-dimethylaminopropylmaleimide (ADMAPM) copolymer was then reacted with methyl iodide to yield a poly(methyl iodide quaternized acrylamide–N,N-dimethylaminopropylmaleimide) copolymer [poly(MIQADMAPM)]. Its aqueous solution properties were studied by measurements of reduced viscosity, intrinsic viscosity, and flocculation test in this study. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentration of the added salt. “Soft” salt anions were more easily bound to the quaternary ammonium cation (R₄N⁺) of poly(MIQADMAPM) than were “hard” salt anions. Halide anions are hard anions; consequently, hard cations were more easily attracted to halide anions and reduced the binding degree of halide anion on the quaternary ammonium group (R₄N⁺). The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain was contrasted with polyampholyte. The effect of various flocculants on flocculation in different pH values was accessed in this study. © 1996 John Wiley & Sons, Inc.     

Effect of pH on the drug release rate from a new polymer–drug conjugate system

The corresponding N‐hydroximide and N‐methyl‐N‐hydroximide of poly[ethylene‐alt‐(maleic anhydride)] (weight average molecular weight (M_w) of 100–500 g mol^?1) were prepared as a new oral drug delivery system. Syntheses of N‐hydroximide and N‐methylhydroxamic acid of poly[ethylene‐alt‐(maleic anhydride)] were carried out by chemical modification of polymer with hydroxylamine and N‐methylhydroxylamine, respectively, to give water‐soluble polymers. These activated polymers were immobilized with ketoprofen in the presence of dicyclohexylcarbodiimide to give the corresponding water‐insoluble ketoprofen conjugates. All products were characterized by elemental analysis as well as Fourier transform infrared and ¹H NMR spectra. In vitro release of ketoprofen was studied by measuring UV absorption at λ_max = 260 nm as a function of time. This study demonstrated the potential use of N‐hydroximide and N‐methyl‐N‐hydroxamic acid of poly[ethylene‐alt‐(maleic anhydride)] as a drug delivery system. Controlled release was studied at different pH values and at different temperatures. At physiological temperature, the amount of drug released increased with increasing pH. The copolymer‐drug adducts released the drug very slowly at the low pH found in the stomach thus protecting the drug from the action of high acid conditions and resident digestive enzymes. These N‐hydroxamic acid polymer‐drug conjugates were found to be potentially useful in the delivery of macromolecular drugs to targeted sites in the lower gastrointestinal tract and the colon area. Copyright © 2007 Society of Chemical Industry     

Preparation and characterization of high melt strength polypropylene with long chain branched structure by the reactive extrusion process

The reactive extrusion of maleic anhydride grafted polypropylene (PP‐g‐MAH) with ethylenediamine (EDA) as coupling agent is carried out in a corotating twin‐screw extruder to produce long chain branched polypropylene (LCBPP). Part of PP‐g‐MAH is replaced by maleic anhydride grafted high‐density polyethylene (HDPE‐g‐MAH) or linear low‐density polyethylene (LLDPE‐g‐MAH) to obtain hybrid long chain branched (LCB) polyolefins. Compared with the PP‐g‐MAH, PE‐g‐MAH, and their blends, the LCB polyolefins exhibit excellent dynamic shear and transient extensional rheological characteristics such as increased dynamic modulus, higher low‐frequency complex viscosity, broader relaxation spectra, significantly enhanced melt strength and strain‐hardening behaviors. The LCB polyolefins also have higher tensile strength, tensile modulus, impact strength and lower elongation at break than their blends. Furthermore, supercritical carbon dioxide (scCO₂) is constructively introduced in the reactive extrusion process. In the presence of scCO₂, the motor current of the twin extruder is decreased and LCB polyolefins with lower melt flow rate (MFR), higher complex viscosity and increased tensile strength and modulus can be obtained. This indicates that the application of scCO₂ can reduce the viscosity of melt in extruder, enhance the diffusion of reactive species, and then facilitate the long chain branching reaction between anhydride group and primary amine group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of cross‐linker on morphology,catalytic activity,and recyclability of immobilized palladium chloride

Two kinds of immobilized palladium (Pd) catalysts were prepared by reversible addition fragmentation chain transfer polymerization of pyridine‐containing monomer followed by immobilizing palladium chloride (PdCl₂) on block copolymers. Namely, one of them includes the cross‐linking structure of maleic anhydride with 1,6‐diaminohexane (cross‐linker), polystyrene‐block‐poly(4‐(4‐vinylbenzyloxy)butylpicolinate‐alt‐maleic anhydride)‐Pd (PS‐b‐P(VBP‐alt‐MAn)‐Pd), and the other is its non‐cross‐linking counterpart, polystyrene‐block‐poly(4‐(4‐vinylbenzyloxy) butylpicolinate)‐Pd (PS‐b‐PVBP‐Pd). From transmission electron microscopy images, it could be observed that they both assembled into micelles in the selective solvents. The Pd of PS‐b‐P(VBP‐alt‐MAn)‐Pd located in the core of micelles, whereas the Pd of PS‐b‐PVBP‐Pd was on the shell of the micelles. The PS‐b‐P(VBP‐alt‐MAn)‐Pd can be continuously used for five times without any appreciable loss of activity in the aqueous Suzuki‐coupling reaction. However, the catalytic activities of the PS‐b‐PVBP‐Pd decreased sharply with the increase in the recycle times. Thus, this promising cross‐linking strategy not only greatly restrained the loss of Pd in the catalytic cycles, but also effectively maintained the immobilized Pd catalyst's high activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of low‐density polyethylene/banana starch films containing compatibilizer and photosensitizer

Composite films containing various percentages of banana starch and low‐density polyethylene (LDPE) were prepared. The effects of the compatibilizer, banana starch content, and photosensitizer content on the thermal and tensile properties of these films were investigated. The banana starch content was varied from 5 to 20 wt % of LDPE, whereas benzophenone was added as a photosensitizer in three different amounts (0.25, 0.5, and 1 wt %) based on LDPE. In these films PE‐graft‐maleic anhydride (PE‐g‐MA) was used as a compatibilizer at 10 wt % banana starch. It was found that the thermal stability of the composite films remained unchanged with respect to the amount of banana starch and benzophenone content. The addition of banana starch had no effect on the melting temperature and degree of crystallinity of the films. Similarly, PE‐g‐MA had no effect on the melting temperature but decreased the degree of crystallinity of the LDPE phase. Benzophenone caused an increase in the melting temperature but decreased the degree of crystallinity of LDPE in the films. Increasing the amount of banana starch decreased the tensile properties of the composite films. The addition of PE‐g‐MA as a compatibilizer increased the tensile properties compared with the uncompatibilized films. However, benzophenone had no effect on the tensile properties of the blend films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2717–2724, 2006     

Photobiodegradation of low‐density polyethylene/banana starch films

The effects of the starch content, photosensitizer content, and compatibilizer on the photobiodegradability of low‐density polyethylene (LDPE) and banana starch polymer blend films were investigated. The compatibilizer and photosensitizer used in the films were PE‐graft‐maleic anhydride (PE‐g‐MA) and benzophenone, respectively. Dried banana starch at 0–20% (w/w) of LDPE, benzophenone at 0–1% (w/w) of LDPE, and PE‐g‐MA at 10% (w/w) of banana starch were added to LDPE. The photodegradation of the blend films was performed with outdoor exposure. The progress of the photodegradation was followed by determining the carbonyl index derived from Fourier transform IR measurements and the changes in tensile properties. Biodegradation of the blend films was investigated by a soil burial test. The biodegradation process was followed by measuring the changes in the physical appearance, weight loss, and tensile properties of the films. The results showed that both photo‐ and biodegradation rates increased with increasing amounts of banana starch, whereas the tensile properties of the films decreased. The blends with higher amounts of benzophenone showed higher rates of photodegradation, although their biodegradation rates were reduced with an increase in benzophenone content. The addition of PE‐g‐MA into polymer blends led to an increase in the tensile properties whereas the photobiodegradation was slightly decreased compared to the films without PE‐g‐MA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2725–2736, 2006     

Degradability of extruded polyethylene/chitosan blends compatibilized with polyethylene‐graft‐maleic anhydride under natural weathering

The impact of chitosan on the natural weathering behavior of two blends obtained by mixing either polyethylene (PE) with chitosan or PE, chitosan and polyethylene‐graft‐maleic anhydride (PEgMA) as a compatibilizer is analyzed. In order to follow the weathering behavior of both the uncompatibilized and compatibilized systems, the blend films are exposed to outdoor conditions for 6 months. The weathering behavior of the films is monitored by mechanical tests, spectroscopic Fourier transform infrared, and morphological analyses at different weathering periods of time. The presence of chitosan in the blends accelerates significantly the degradation of the films. Apparently, PEgMA also accelerates the photo‐oxidation rate of the films. This behavior appears to be related to the photo‐oxidative instability of maleic anhydride, and also to the better dispersion of chitosan in the PE matrix, which is due to the interactions in the PE/chitosan interface caused by the addition of the compatibilizer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41045.     

Dynamic rheology and morphology of HDPE‐fumed silica composites: Effect of interface modification

In the present study, high density polyethylene (HDPE)‐based composites containing different amounts of fumed silica (FS) were prepared by melt compounding in a corotating twin screw extruder. Polyethylene‐g‐maleic anhydride copolymer (PE‐g‐MA) containing 1 wt% maleic anhydride was used for interface modification between filler and polymer. The interaction between the surface hydroxyl groups of fumed silica nanoparticles with maleic anhydride groups of PE‐g‐MA led to a finer dispersion of the filler in the HDPE matrix. The terminal complex viscosity and terminal storage modulus were highest at 1 wt% filler loading due to widely spread network formation by FS nanoparticles. This filler network plausibly got disturbed at higher filler content and/or interface modification which was reflected in their stress relaxation behavior also. The dynamic rheological behavior of the composites was explained in terms of morphological observations. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effects of clay dispersion on the foam morphology of LDPE/clay nanocomposites

Intercalated and exfoliated low‐density polyethylene (LDPE)/clay nanocomposites were prepared by melt blending with and without a maleated polyethylene (PE‐g‐MAn) as the coupling agent. Their morphology was examined and confirmed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of clay content and dispersion on the cell morphology of nanocomposite foams during extrusion foaming process were also thoroughly investigated, especially with a small amount of clay of 0.05–1.0 wt%. This research shows the optimum clay content for achieving microcellular PE/clay nanocomposite foams blown with supercritical CO₂. It is found that < 0.1 wt% of clay addition can produce the microcellular foam structure with a cell density of > 10⁹ cells/cm³ and a cell size of ～ 5 μm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2129–2134, 2007     

Gasoline permeation behavior and mechanical properties of polyamide 6/nanoclay,polyamide 6/PE‐g‐maleic anhydride blend,and polyamide 6/PE‐g‐maleic anhydride/clay nanocomposite

In this article, polyamide 6 (PA6)/clay nanocomposites, PA6/polyethylene grafted maleic anhydride (PE‐g‐MA) blends, and PA6/PE‐g‐MA/clay nanocomposites were prepared and their gasoline permeation behavior and some mechanical properties were investigated. In PA6/clay nanocomposites, cloisite 30B was used as nanoparticles, with weight percentages of 1, 3, and 5. The blends of PA6/PE‐g‐MA were prepared with PE‐g‐MA weight percents of 10, 20, and 30. All samples were prepared via melt mixing technique using a twin screw extruder. The results showed that the lowest gasoline permeation occurred when using 3 wt % of nanoclay in PA6/clay nanocomposites, and 10 wt % of PE‐g‐MA in PA6/PE‐g‐MA blends. Therefore, a sample of PA6/PE‐g‐MA/clay nanocomposite containing 3 wt % of nanoclay and 10 wt % of PE‐g‐MA was prepared and its gasoline permeation behavior was investigated. The results showed that the permeation amount of PA6/PE‐g‐MA/nanoclay was 0.41 g m^?2 day^?1, while this value was 0.46 g m^?2 day^?1 for both of PA6/3wt % clay nanocomposite and PA6/10 wt % PE‐g‐MA blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40150.     

Preparation of high‐performance polyethylene via a novel processing method of combining dynamic vulcanization with a silane‐grafted water‐crosslinking technique

A novel processing method of combining dynamic vulcanization with the silane‐grafted water‐crosslinking technique to improve the comprehensive properties of polyethylene (PE) is reported. PE was grafted with vinyl triethoxysilane (VTEO) first, and then, N,N,N′,N′‐ tetragylcidyl‐4,4′‐diaminodiphenylmethane epoxy resin was dynamically cured in a PE‐g‐VTEO matrix through a twin‐screw extruder to prepare PE‐g‐VTEO/epoxy blends. Polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) was used as a compatibilizer to improve the interaction between PE‐g‐VTEO and the epoxy resin. The results show that the novel processing method improved the strength, stiffness, and toughness of the blends, especially the heat resistance of the blends, by the addition of the dynamically cured epoxy resin as the reinforcement. PE‐g‐MAH increased the compatibility between PE‐g‐VTEO and the epoxy resin, which played an important role in the improvement of the comprehensive properties of the blends. In addition, after treatments in both hot air and hot water, the comprehensive properties of blends were further improved, thanks to the further curing reaction of epoxy with PE‐g‐VTEO. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of HDPE/SEBS‐g‐MAH and its effect on mechanical properties of HDPE/wood flour composites

In this article, high density polyethylene/styrene‐ethylene‐butylene‐styrene block copolymer blends (HDPE/SEBS) grafted by maleic anhydride (HDPE/SEBS‐g‐MAH), which is an effective compatibilizer for HDPE/wood flour composites was prepared by means of torque rheometer with different contents of maleic anhydride (MAH). The experimental results indicated that MAH indeed grafted on HDPE/SEBS by FTIR analysis and the torque increased with increasing the content of maleic anhydride and dicumyl peroxide (DCP). Styrene may increase the graft reaction rate of MAH and HDPE/SEBS. When HDPE/SEBS MAH was added to HDPE/wood flour composites, tensile strength and flexural strength of composites can reach 25.9 and 34.8 MPa in comparison of 16.5 and 23.8 MPa (without HDPE/SEBS‐g‐MAH), increasing by 157 and 146%, respectively. Due to incorporation of thermoplastic elastomer in HDPE/SEBS‐g‐MAH, the Notched Izod impact strength reached 5.08 kJ m^?2, increasing by 145% in comparison of system without compatibilizer. That HDPE/SEBS‐g‐MAH improved the compatibility was also conformed by dynamic mechanical measurement. Scanning electron micrographs provided evidence for strong adhesion between wood flour and HDPE matrix with addition of HDPE/SEBS‐g‐MAH. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007