甲基化木粉与PE-g-MAH对木粉/HDPE复合材料力学性能的协同作用研究

主要研究了木粉表面甲基化改性和增容剂马来酸酐接枝聚乙烯(PE-g-MAH)对木粉/高密度聚乙烯(HDPE)复合材料力学性能的协同作用.木粉经表面甲基化处理后,与10％PE-g-MAH协同使用,甲基化木粉/PE-g-MAH/HDPE复合材料的拉伸强度、弯曲强度和冲击强度均明显高于未改性木粉/PE-g-MAH/HDPE复合...     

木粉的碱化处理对木塑复合材料性能的影响

采用木粉填充高密度聚乙烯（HDPE）制备复合材料。为增强亲水性的木粉和憎水性的HDPE基质之间的化学亲和力,对木粉碱化处理。研究了相容剂用量和木粉的碱化处理对复合材料力学性能的影响。结果显示,马来酸酐接枝HDPE可明显提高复合材料的力学性能．表现出很好的增容效果：与用未碱化处理的木粉填充的复合材料相比,木粉的碱化处理使复合材料的弯曲强度和弯曲模量分别下降20．4％和36．2％：在不使用相容剂的情况下,木粉的碱化处理也会使复合材料的拉伸强度下降．但在使用适量相容剂后．则可使复合材料的拉伸强度从未处理时的30．3MPa提高到36．5MPa,与纯HDPE相比,拉伸强度提高了44.8％。     

Rheological and mechanical properties of composites made from wood flour and recycled LDPE/HDPE blend

The effect of compounding method is studied with respect to the rheological behavior and mechanical properties of composites made of wood flour and a blend of two main components of plastics waste in municipal solid waste, low-density polyethylene (LDPE) and high-density polyethylene (HDPE). The effects of recycling process on the rheological behavior of LDPE and HDPE blends were investigated. Initially, samples of virgin LDPE and HDPE were thermo-mechanically degraded twice under controlled conditions in an extruder. The recycled materials and wood flour were then compounded by two different mixing methods: simultaneous mixing of all components and pre-mixing, including the blending of polymers in molten state, grinding and subsequent compounding with wood flour. The rheological and mechanical properties of the LDPE/HDPE blend and resultant composites were determined. The results showed that recycling increased the complex viscosity of the LDPE/HDPE blend and it exhibited miscible behavior in a molten state. Rheological testing indicated that the complex viscosity and storage modulus of the composites made by pre-mixing method were higher than that made by the simultaneous method. The results also showed that melt pre-mixing of the polymeric matrix (recycled LDPE and HDPE) improved the mechanical properties of the wood–plastic composites.     

HDPE-g-MAH增容HDPE/木粉复合材料润滑剂的优选和热性能研究

使用自制HDPE-g-MAH做增容剂,通过双螺杆挤出机熔融共混制备了四种不同润滑剂的HDPE/木粉复合材料,对样品进行了力学性能测试；采用差示扫描量热分析(DSC)和热变形温度曲线测试考察了木粉和相容剂的加入分别对复合材料热、力学性能的影响。结果表明,润滑剂的种类和用量对HDPE/木塑复合材料的力学性能有较大的影响：与其它润滑剂相比,聚乙烯蜡具有更好的润滑作用和分散作用；DSC测试显示,木粉的加人提高了聚乙烯基体结晶度,相容剂使木粉的界面得到明显的改善,有利于聚乙烯的结晶；热变形温度曲线对比表明,木塑复合材料的热变形温度较聚乙烯有了很大的提高,有着更好的耐热性能。     

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     

The effect of maleic anhydride grafting efficiency on the flexural properties of polyethylene composites

Many authors have reported on the property enhancements possible by compounding high density polyethylene (HDPE) with fillers to produce composites. It is accepted that polyethylene combined with materials such as nanoclay or wood flour will not yield favorable properties unless a compatibilizing material is used to form a link. In this work, compatibilized HDPE was produced by grafting maleic anhydride (MA) to its backbone in a twin screw extruder using a peroxide initiated reactive process. Fourier transform infrared spectroscopy (FTIR) was used to examine the effects of varying peroxide and MA levels on the grafting percentage and it was found that a high percentage could be achieved. The gel content of each HDPE‐g‐MA batch was determined and twin bore rheometry analysis was carried out to examine the effects of crosslinking and MA grafting on the melt viscosity. These HDPE‐g‐MA compatibilizers were subsequently compounded with nanoclay and wood flour to produce composites. The composite materials were tested using a three point bending apparatus to determine the flexural modulus and strength and were shown to have favorable mechanical properties when compared with composites containing no compatibilizer. X‐ray diffraction (XRD) was used to examine the effects of grafted MA content on the intercalation and exfoliation levels of nanoclay composites. The results from XRD scans showed that increased intercalation in polymer nanoclay composites was achieved by increasing the grafted MA content. This was confirmed using a scanning electron microscope, where images produced showed increased levels of dispersion and reductions in nanoclay agglomerates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effectiveness of functionalized polyolefins as compatibilizers for polyethylene/wood flour composites

The effects of various types of compatibilizers on the mechanical properties of high‐density polyethylene/wood flour (HDPE/WF) composite were investigated. Functionalized polyolefins such as maleated and acrylic acid grafted polyethylenes, maleated polypropylene (PPgMA) and styrene‐ethylene/butylene‐styrene triblock copolymer (SEBSgMA) were incorporated to reduce the interfacial tension between the polyethylene matrix and the wood filler. Among them, it was found that maleated linear low‐density polyethylene (LLDPEgMA) gave maximum tensile and impact strength of the composites, presumably because of better compatibility with the HDPE matrix. Similar but less enhanced improvements in the mechanical properties, depending on the compatibilizer loading, were seen for the SEBSgMA system. Whereas acrylic acid grafted high‐density polyethylene (HDPEgAA) and maleated polypropylene (PPgMA) only slightly improved tensile modulus and tensile strength; and they both increased with increasing loadings of compatibilizers. A scanning electron microscopic study was employed to reveal the interfacial region and confirm these findings. In addition, dynamical mechanical thermal measurements also revealed the interaction between filler and matrix, and FTIR spectroscopy was used to assign the chemical fixation and the various chemical species involved at the surface of the wood fillers before and after surface treatment.     

Effects of filler–filler and polymer–filler interactions on rheological and mechanical properties of HDPE–wood composites

High‐density polyethylene (HDPE)–wood composite samples were prepared using a twin‐screw extruder. Improved filler–filler interaction was achieved by increasing the wood content, whereas improved polymer–filler interaction was obtained by adding the compatibilizer and increasing the melt index of HDPE, respectively. Then, effects of filler–filler and polymer–filler interactions on dynamic rheological and mechanical properties of the composites were investigated. The results demonstrated that enhanced filler–filler interaction induced the agglomeration of wood particles, which increased the storage modulus and complex viscosity of composites and decreased their tensile strength, elongation at break, and notched impact strength because of the stress concentration. Stronger polymer–filler interaction resulted in higher storage modulus and complex viscosity and increased the tensile and impact strengths due to good stress transfer. The main reasons for the results were analyzed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

HDPE-g-MAH增容HDPE/木粉复合材料的制备及加工设备的研究

使用HDPE-g-MAH做增容剂,通过双螺杆挤出机制备了HDPE/木粉复合材料,对HDPE-g-MAH进行量变实验,通过力学性能测试确定了最佳用量,并利用SEM对材料微观形貌进行了观察。在此基础上又采用单螺杆挤出机、开炼机和密炼机等不同的加工设备分别制备了木塑复合材料,对力学性能进行了对比表征。结果表明:HDPE-g-MAH的加入很好地改善了木塑复合材料的界面相容性、力学性能和木粉的分散性,HDPE-g-MAH的最佳用量为5份;而且只有使用剪切效果优良的双螺杆挤出机才能制备出性能优异的木塑复合材料。     

Processability,morphology and mechanical properties of wood flour reinforced high density polyethylene composites

Abstract

Wood flour reinforced high density polyethylene (HDPE) composites have been prepared and their rheological properties measured. The melt viscosity decreased as the processing temperature increased and the wood flour content decreased. A power law model was used to describe the pseudoplasticity of these melts. Adding wood flour to HDPE produced an increase in tensile strength and modulus. Composites compounded in a twin screw extruder and treated with a coupling agent (vinyltrimethoxysilane) or a compatibliser (HDPE grafted with maleic anhydride) exhibited better mechanical properties than the corresponding unmodified composites because of improved dispersion and good adhesion between the wood fibre and the polyalkene matrix. Scanning electron microscopy of the fracture surfaces of these composites showed that both the coupling agent and compatibiliser gave superior interfacial strength between the wood fibre and the polyalkene matrix.     

Enhancement of wood/polyethylene composites via compatibilization and incorporation of organoclay particles

Despite many advantages of wood–polyethylene composites, the shortcomings of this kind of composite include relatively low modulus, low notched impact resistance, relatively large thermal expansion, as well as substantial creep. In this article, in addition to using maleic anhydride grafted polyethylene as compatibilizer, organoclay was introduced into the polyethylene matrix so as to further enhance the thermal and mechanical performance. First, the influence of maleic anhydride grafted polyethylene type and loading on the morphology and properties of wood/HDPE composites was studied. Then, the effects of organoclay loading and of the compounding procedure on the wood/HDPE composites were investigated. The compatibilization was found to result in better polymer impregnation on the wood, reduced linear thermal expansion coefficients, and significantly improved mechanical properties. Incorporation of organoclay further reduced the thermal expansion and elevated the heat deflection temperature. More compatibilizer is needed to maintain the mechanical properties with the presence of clay. POLYM. ENG. SCI., 47:797–803, 2007. © 2007 Society of Plastics Engineers     

Crystallization and melting behavior of HDPE in HDPE/teak wood flour composites and their correlation with mechanical properties

The nonisothermal crystallization behavior and melting characteristics of high‐density polyethylene (HDPE) in HDPE/teak wood flour (TWF) composites have been studied by differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) methods. Composite formulations of HDPE/TWF were prepared by varying the volume fraction (?_f) of TWF (filler) from 0 to 0.32. Various crystallization parameters evaluated from the DSC exotherms were used to study the nonisothermal crystallization behavior. The melting temperature (T_m) and crystallization temperature (T_p) of the composites were slightly higher than those of the neat HDPE. The enthalpy of melting and crystallization (%) decrease with increase in the filler content. Because the nonpolar polymer HDPE and polar TWF are incompatible, to enhance the phase interaction maleic anhydride grafted HDPE (HDPE‐g‐MAH) was used as a coupling agent. A shift in the crystallization and melting peak temperatures toward the higher temperature side and broadening of the crystallization peak (increased crystallite size distribution) were observed whereas crystallinity of HDPE declines with increase in ?_f in both DSC and WAXD. Linear correlations were obtained between crystallization parameters and tensile and impact strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A commercially viable compatibilizer system for wood–polyethylene composites

A commercially viable compatibilizer system containing poly(diphenylmethane diisocyanate) (PMDI) and stearic acid was developed for improving the interfacial adhesion between wood and polyethylene (PE). The treatment of PE with PMDI before mixing with wood increased both the modulus of rupture (MOR) and the modulus of elasticity (MOE) of the resulting wood–PE composites. Addition of stearic acid at certain dosages further increased MOR of the resulting composites. The PMDI–stearic acid compatibilizer system was more effective in increasing both the MOR and MOE of the resulting wood–PE composites than maleic anhydride-grafted polyethylene (MAPE), a commonly used commercial compatibilizer. The compatibilization mechanisms for the PMDI–stearic acid system were investigated by Fourier transform infrared (FT-IR) spectroscopy. The water-resistance test revealed that the composites with the PMDI–stearic acid system were statistically more water-resistant than those with MAPE.     

Effects of a new compatibilizer system on the flexural properties of wood–polyethylene composites

A novel wood–plastic compatibilizer system containing a paper wet‐strength agent as a wood‐binding domain and stearic anhydride as a polyethylene (PE) binding domain was investigated. Treatment of wood flour with a commercial paper wet‐strength agent Kymene® 557H (simply called Kymene) before the mixing of PE and the wood flour increased the modulus of rupture (MOR) and the modulus of elasticity (MOE) of the resulting wood–PE composites. Addition of stearic acid in the mixing of PE and the wood–Kymene mixture further increased the MOR and MOE. Stearic anhydride was even more effective than stearic acid in the increase of the MOR and MOE. Compared to wood–PE composites without a compatibilizer, the stearic anhydride–Kymene compatibilizer system increased the MOR by about 33% and the MOE by about 40%. The stearic anhydride–Kymene compatibilizer system gave a slightly lower MOR, but higher MOE than those of the commercially used compatibilizer (maleic anhydride‐grafted polypropylene). The compatibilization mechanisms were proposed as follows: Kymene not only bound to wood fibers, but also strengthened and stiffened the wood fibers. Stearic anhydride formed covalent linkages such as ester and amide with the Kymene‐consolidated wood fibers and the long hydrocarbon chain of the stearic anhydride bonded to the PE matrix through entanglements and/or cocrystallization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3667–3672, 2004     

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.     

Incorporation effect of enzymatic hydrolysis lignin on the mechanical and rheological properties of the resulting wood flour/high‐density polyethylene composites

Enzymatic hydrolysis lignin (EHL) from ethanol production was used as an additive to incorporate in the wood flour/high‐density polyethylene (HDPE) composite during the melt extrusion, and the incorporating effects on the mechanical and rheological properties of the resulting composites were investigated. The addition of EHL caused an improvement in both the tensile strength and impact strength, and a reduction in the complex viscosity of the composites as evidenced by the rotational rheometry, which suggests an increased flowability of the composite melt due to incorporation of EHL. The water absorption and swelling of the composites decreased with increasing EHL content during water immersion test. The scanning electron microscopy micrographs of EHL incorporated wood flour/high‐density polyethylene composites showed a homogeneous dispersion of wood flour and EHL in the HDPE matrix. POLYM. COMPOS., 37:379–384, 2016. © 2014 Society of Plastics Engineers     

Wood‐thermoplastic composites from wood flour and high‐density polyethylene

High‐density polyethylene/wood flour (HDPE/WF) composites were prepared by a twin‐screw extruder. The effects of WF, silane coupling agents, polymer compatibilizers, and their content on the comprehensive properties of the WF/HDPE composites have been studied in detail, including the mechanical, thermal, and rheological properties and microstructure. The results showed that both silane coupling agents and polymer compatibilizers could improve the interfacial adhesion between WF and HDPE, and further improve the properties of WF/HDPE composites, especially with AX8900 as a compatibilizer giving higher impact strength, and with HDPE‐g‐MAH as a compatibilizer giving the best tensile and flexural properties. The resultant composite has higher strength (tensile strength = 51.03 MPa) and better heat deflection temperature (63.1°C). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of polyethylene terephthalate/polyethylene/near infrared reflective pigment composites

Polyethylene terephthalate/high density polyethylene (PET/HDPE) composites containing a near infrared reflective (NIR, nickel antimony titanium yellow rutile) pigment was prepared using ethylene‐glycidyl methacrylate‐vinyl acetate (EGMA‐VA) as a compatibilizer to increase the infrared reflection of PET/HDPE and limit the thermal heat accumulation in light of environmental and energy conservation concerns. HDPE was premixed with NIR to form N‐HDPE masterbatch. A good interfacial bonding between PET matrix and HDPE dispersed phase with the help of compatibilizer was confirmed through Fourier transform‐infrared spectra, scanning electron microscopy, and torque rheometer. For PET/N‐HDPE composites, the major X‐ray diffraction peaks and melting behaviors remained unchanged, indicating the limited alternation of crystalline structure for the composite systems with or without compatibilizer. The observed increment in the crystallization temperature of PET for the investigated PET/N‐HDPE composites was mainly due to the nucleation role of both inorganic NIR and HDPE. Tensile strength and elongation at break for compatibilized cases at various N‐HDPE contents conferred higher values than those of the corresponding counterparts without compatibilizer. Yet, Young's modulus for compatibilized systems was about 40% lower than that for systems without compatibilizer, attributed to the rubbery nature of EGMA‐VA. With the inclusion of NIR into HDPE to form PET/N‐HDPE composites with or without EGMA‐VA compatibilizer, the values of reflectance increased to a great degree. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40830.     

Thermal,crystallization, and dynamic rheological behavior of wood particle/HDPE composites: Effect of removal of wood cell wall composition

This study investigated the effect of removal of wood cell wall composition on thermal, crystallization, and dynamic rheological behavior of the resulting high density polyethylene (HDPE) composites. Four types of wood particle (WP) with different compositions: native wood flour (WF), hemicellulose‐removed wood particle (HR), lignin‐removed wood particle (holocellulose, HC), and both hemicellulose and lignin removed particle (α‐cellulose, αC) were prepared and compounded with HDPE using extruder, both with and without maleated polyethylene (MAPE). Results show that removal of the hemicellulose improved the thermal stability of composites, while removal of the lignin facilitated thermal decomposition. WPs acted as nucleating agents and facilitated the process of crystallization, thereby increasing the crystallization temperature and degree of crystallinity. The crystallization nucleation and growth rate of αC and HR based composites without MAPE decreased, as compared with WF based one. Composite melts with and without MAPE exhibited a decreasing order of storage modulus, loss modulus, and complex viscosity as αC > WF > HR > HC and αC > HR > WF > HC, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40331.     

用废木粉增强聚乙烯的研究

本研究采用废木粉为填料增强改性高密度聚乙烯。评价了马来酸酐接枝高密度聚乙烯（MAH-g-HDPE）对聚乙烯基木塑复合材料的增客效果，研究了木粉含量对复合材料力学性能和其它性能的影响，详细阐述了木粉的增强作用机理。研究结果表明：MAH-g-HDPE可显著增进憎水性基质和亲水性木粉之间的界面相互作用，明显改进复合材料的力学性能；在使用适当相客剂的情况下，木粉可明显提高聚乙烯的拉伸强度、弯曲强度和弯曲模量，具有良好的增强效果；当木粉含量为60％时，复合材料的拉伸强度、弯曲强度、弯曲模量分别高达38MPa、54MPa和3500MPa，若与纯基质相比，分别提高了43．4％、176％和283％。这些实验结果表明，木粉对聚乙烯具有明显的增强效果。