硅烷偶联剂对HDPE/木粉复合材料性能的影响

使用经硅烷偶联剂HP-172和HP-174改性的木粉制备了HDPE/木粉复合材料,研究了偶联剂用量对其性能的影响。实验结果表明:当使用1.5%的HP-172处理木粉后,可使复合材料的各项力学性能提高30%以上;HP-174的用量为1%~1.5%也得到了较好的改性效果。通过FIR和SEM分析发现,硅烷偶联剂可与木粉表面发生化学反应,从而提高了HDPE与木粉的界面粘合强度,使复合材料的力学性能得以提高     

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复合材料,其原因在于在PE-g-MAH的作用下,甲基化木粉在聚合物基体中分布更加均匀,两者的界面作用力更高,即甲基化木粉和PE-g-MAH对提升木粉/HDPE复合材料的力学性能具有良好的协同作用。     

Mechanical properties of wood flake–polyethylene composites. II. Interface modification

This article discusses the methods of interface modification of composites based on raw wood flakes and high‐density polyethylene (HDPE) and the effects of these modifications on composite properties. An HDPE matrix was modified by a reaction with maleic anhydride (MA) in a twin‐screw extruder and then compounded with wood flakes to produce wood–polyethylene composites. Wood flakes were modified by a reaction with a silane coupling agent in an aqueous medium before being compounded with HDPE to produce silane‐modified WPCs. Differential scanning calorimetry and Fourier transform infrared spectroscopy data provide evidence for the existence of a polyethylene (PE)–silane‐grafted wood structure, which acts as a compatibilizer for wood flakes and PE. The results of MA‐modified composites indicate that some maleated HDPE is reacting with wood through esterification to form a compatibilizer for wood flakes and HDPE. Significant improvements in tensile strength, ductility, and Izod impact strength were obtained. Scanning electron micrographs provide evidence for strong interactions between the wood flakes and the matrix agent. The results indicate that 1–2 wt % MA modification on HDPE and 1–3 wt % silane treatment on wood flakes provide WPCs with the optimum properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2505–2521, 2002     

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     

Studies on recyclable composites: nylon fibre reinforced high density polyethylene composites

Abstract

A commercial grade of high density polyethylene (HDPE) matrix reinforced with nylon fibre up to 30 wt-% of HDPE was studied as a potential candidate for recyclable composites. These composite materials show improvement in mechanical properties such as tensile strength and flexural strength. Modification using styrene maleic anhydride – grafted HDPE significantly improved the mechanical and thermal properties. The HDPE/nylon composites/blends obtained by recycling of the composites also show good mechanical properties.     

Increased Water Resistance of Bamboo Flour/Polyethylene Composites

Abstract

To improve the water resistance of bamboo flour/high-density polyethylene (HDPE) composites, the effects of plastic content, coupling agents, and the addition of micro-fibrillated cellulose (MFC) on formulations were studied, and their rheological and mechanical properties were evaluated. The composites were prepared by injecting molding with a basic composition of equivalent amounts of bamboo flour and HDPE, and the melting fluidity of the compounds, tensile strength, and tensile modulus of the composites were determined. An increase in water resistance was detected in all three tests. By increasing the plastic content, negative effects such as a decreased tensile modulus were observed. When evaluating the compatibility between bamboo flour and plastic using coupling agents and MFC addition, positive effects were noted for water resistance, melting fluidity, and tensile modulus. We also confirmed that the procedure used to increase the compatibility between bamboo flour and plastic could easily be used for industrial applications by changing the coupling agents. Overall, a novel positive property (increased tensile modulus) and an increased water resistance were observed after MFC addition.     

Curing Characteristics and Mechanical Properties of Oil Palm Wood Flour Reinforced Epoxidized Natural Rubber Composites

Abstract

The paper reports on the curing characteristics and mechanical properties of oil palm wood flour (OPWF) reinforced epoxidized natural rubber (ENR) composites. Three sizes of OPWF at different filler loadings were compounded with a two roll mill. The cure (t ₉₀) and scorch times of all filler size decrease with increasing OPWF loading. Increasing OPWF loading in ENR compound resulted in reduction of tensile strength and elongation at break but increased tensile modulus, tear strength and hardness. The composites filled with smaller OPWF size showed higher tensile strength, tensile modulus and tear strength. Scanning electron microscope (SEM) micrographs showed that at lower filler loading the fracture of composites occurred mainly due to the breakage of fibre with minimum pull-out of fibres from the matrix. However as the filler loading is increased, the fibre pull-out became very prominent due to the lack of adhesion between fibre and rubber matrix.     

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。     

Effects of the accelerated freeze‐thaw cycling on physical and mechanical properties of wood flour‐recycled thermoplastic composites

This study investigated durability performance of wood‐plastic composites (WPCs) that were exposed to accelerated cycling of water immersion followed by freeze thaw (FT). The WPCs used in this study were made of high‐density polyethylene (HDPE) or polypropylene (PP) with radiata pine (Pinus radiata) wood flour using hot‐press molding. These two types of plastics included both recycled and virgin forms in the formulation. In the experiments, surface color, flexural properties, and dimensional stability properties (water absorption and thickness swelling) were measured for the FT cycled composites and the control samples. Interface microstructures and thermal properties of the composites were also investigated. The results show that the water absorption and the thickness swelling of the composites increased with the FT weathering. In the meantime, the flexural strength and stiffness decreased. Scanning electron microscopy (SEM) images of the fractured surfaces confirmed a loss of interface bonding between the wood flour and the polymer matrix. Differential scanning calorimetry (DSC) showed a decrease in crystallization enthalpy and crystallinity of the wood flour‐plastic composites as compared with the neat PP and HDPE samples. The crystallinity of the FT cycled composites using the virgin plastics (vPP and vHDPE) increased; however, the composites with the recycled plastics decreased in comparison with corresponding control samples. In general, the properties of the composites were degraded significantly after the accelerated FT cycling. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Effect of Coupling Agent Concentration,Fiber Content,and Size on Mechanical Properties of Wood/HDPE Composites

In this study, the influence of coupling agent concentration (0 and 3 wt%), wood fiber content (50, 60, 70, and 80 wt%), and size (40–60, 80–100, and 160–180 mesh) on the mechanical properties of wood/high-density-polyethylene (HDPE) composites (WPCs) was investigated. WPC samples were prepared with poplar wood-flour, HDPE, and polyethylene maleic anhydride copolymer (MAPE) as coupling agent. It was found that the tensile properties and the flexural properties of the composites were improved by the addition of 3 wt% MAPE, and the improved interfacial adhesion was well confirmed by SEM micrographs. It was also observed that the best mechanical properties of wood/HDPE composites can be reached with larger particle size in the range studied, while too-small particle size was adverse for the mechanical properties of wood/HDPE composites. Moreover, the tensile modulus, tensile strength, and flexural strength of WPCs decreased with the increase in fiber content from 50 to 80 wt%; the flexural modulus of WPCs increased with the increase in fiber content from 50 to 70 wt% and then decreased as the fiber content reached 80 wt%. The variances in property performance are helpful for the end-user to choose an appropriate coupling agent (MAPE) concentration, wood fiber content, and particle size based on performance needs and cost considerations.     

两种不同基体木塑复合材料的制备及性能研究

以稻糠代替木粉,分别制备了高密度聚乙烯(HDPE)基体和聚甲醛(POM)基体木塑复合材料。结果表明稻糠含量小于50%时,这两种木塑复合材料均具有良好的加工流动性;稻糠含量从0增加到50%,拉伸强度和冲击强度下降,热变形温度提高;稻糠含量40%时,木塑复合材料韧性相对于单纯树脂下降最小;稻糠含量在40%时,耐热性能改善效果最为明显。综合各因素对木塑复合材料性能的影响,稻糠填充量选在40%较合适。POM基体木塑复合材料在拉伸性能、弯曲性能和耐热性能方面优于HDPE基体木塑复合材料,但在无缺口冲击性能方面HDPE基体木塑复合材料优于POM基体木塑复合材料。     

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     

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     

Mechanical properties of teak wood flour‐reinforced HDPE composites

Mechanical properties such as tensile and impact strength behavior of teak wood flour (TWF)‐filled high‐density polyethylene (HDPE) composites were evaluated at 0–0.32 volume fraction (Φ_f) of TWF. Tensile modulus and strength initially increased up to Φ_f = 0.09, whereas a decrease is observed with further increase in the Φ_f. Elongation‐at‐break and Izod impact strength decreased significantly with increase in the Φ_f. The crystallinity of HDPE also decreased with increase in the TWF concentration. The initial increase in the tensile modulus and strength was attributed to the mechanical restraint, whereas decrease in the tensile properties at Φ_f > 0.09 was due to the predominant effect of decrease in the crystallinity of HDPE. The mechanical restraint decreased the elongation and Izod impact strength. In the presence of coupling agent, maleic anhydride‐grafted HDPE (HDPE‐g‐MAH), the tensile modulus and strength enhanced significantly because of enhanced interphase adhesion. However, the elongation and Izod impact strength decreased because of enhanced mechanical restraint on account of increased phase interactions. Scanning electron microscopy showed a degree of better dispersion of TWF particles because of enhanced phase adhesion in the presence of HDPE‐g‐MAH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Enhanced thermal stability and flame retarding properties of recycled polyethylene based wood composites via addition of polyethylene/nanoclay masterbatch

Abstract

Barrier and mechanical properties of wood powder composites based on recycled polyethylene (RPE) were modified using a commercial nanoclay masterbatch. X-ray diffraction, dynamic rheology and thermogravimetric analysis measurements showed that nanoclay from the selected masterbatch was well dispersed and formed a percolation network in both virgin and RPEs. The resulting nanocomposites promoted the thermal stability of matrix significantly. Modification efficiency of nanoclay, however, was evidently influenced by the type of matrix, where the strongest effect was achieved in a low viscosity virgin high density PE. The masterbatch was incorporated into an industrial formula designed extrusion quality RPE/wood flour composite. Processing procedures, mainly compounding cycles, and material composition, mainly clay content and type of coupling agent, were optimised. Two extrusion cycles led to higher uniformity of resulting composites than one cycle. Addition of a coupling agent, which has medium viscosity and plenty functional groups, led to enhanced tensile strength. The twice compounded composites were well stiffened and strengthened via combination of 6 wt-% clay and medium viscosity coupling agent. All composites without the addition of nanoclay burned faster after ignition and dripped much earlier and more compared to the composites containing nanoclay even with as small amount as 3 wt-% and being compounded once. The material with 6 wt-% clay showed the best sample integrity and burned slowest of all the tested composites. Furthermore, no dripping during combustion was seen for this material. This study shows that the incorporation of nanoclay using the selected masterbatch can effectively improve the flame retarding properties of RPE based wood composites.     

Rheological properties of teak wood flour reinforced HDPE and maize starch composites

Teak wood flour reinforced high density polyethylene and maize starch composites were prepared by using maleic anhydride grafted polyethylene as a compatibilizer. The mechanical properties (tensile and flexural) of all the composites increased after addition of 10%–40% teak wood flour into HDPE matrix. The complex viscosity (η*) was higher for all the composites at the low frequency, but decreased with increasing frequencies indicating a shear thinning behavior of the composites. The storage modulus and loss modulus increased for the composites compared to the HDPE at low frequencies. Damping factor peak of HDPE and composites showed high below 1 Hz, but the peak start decreasing with increasing above 1 Hz. The relaxation behavior of HDPE and the composites after incorporating teak wood flour, maize starch, and compatibilizer was obtained by Han plot. Biodegradability was enhanced with the incorporation of teak wood flour, maize starch into the composites. Appreciable water uptake and the thickness swelling for the composites indicating it's potential for interior, automobile and packaging applications.     

PBAT/木粉复合材料的制备

以木粉和聚己二酸/对苯二甲酸丁二酯(PBAT)为原料,添加硅烷偶联剂,混合均匀后,在开炼机中混炼一定时间制备PBAT/木粉复合材料,从偶联剂种类及其用量、加工温度、加工时间4个方面探讨了制备PBAT/木粉复合材料的最佳工艺条件。研究结果表明,加入的硅烷偶联剂KH–560用量为木粉和PBAT总质量的2%,与木粉和PBAT在130℃下混炼10 min,制备出的PBAT/木粉复合材料的相容性较好,且复合材料的拉伸性能达到最优,拉伸强度和断裂伸长率分别达到12.42 MPa和56.58%。SEM分析表明,添加KH–560后,PBAT/木粉的相容性得到了明显改善,耐水性更好,吸水率从13.04%下降到10.39%,制备出的PBAT/木粉复合材料的耐热性能较原料木粉也得到了较大的提高,在395℃时仅分解40%。     

Comparative study of maleated polypropylene as a coupling agent for recycled low‐density polyethylene/wood flour composites

The effects of the type of coupling agent and virgin polypropylene (PP) content on the mechanical properties and water absorption behavior of recycled low‐density polyethylene/wood flour (WF) composites were investigated. The fractured surfaces of these recycled wood/plastic composites (rWPCs) were examined to gain insight into the distribution and dispersion of WF within the polymer matrix. The results indicate that the use of 100% recycled polymer led to inferior mechanical properties and to a greater degree of moisture absorption and swelling when compared to recycled polymer–virgin PP wood/plastic composites. This could have been related to the poor melt strength and inferior processability of the recycled polymer. The extent of improvement of the mechanical properties depended not only on the virgin PP content in the matrix but also on the presence of maleic anhydride (MA) modified PP as the coupling agent. Higher concentrations of MA group were beneficial; this improvement was attributed to increased chemical bonding (ester linkages) between hydroxyl moieties in WF and anhydride moieties in the coupling agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Foam extrusion of high density polyethylene/wood‐flour composites using chemical foaming agents

A one‐way analysis of variance and thermal analysis were performed in this study to examine the influences of the contents, types (exothermic vs. endothermic), and forms (pure vs. masterbatch) of chemical foaming agents (CFAs), as well as the use of coupling agents, on the density reduction (or void fraction) and cell morphology of extrusion‐foamed neat high density polyethylene (HDPE) and HDPE/wood‐flour composites. The CFA types and forms did not affect the void fractions of both the neat HDPE and HDPE/wood‐flour composites. However, a gas containment limit was observed for neat HDPE foams whereas the average cell size achieved in the HDPE/wood‐flour composite foams remained insensitive to the CFA contents, irrespective of the foaming agent types. The experimental results indicated that the use of coupling agent in the formulation was required to achieve HDPE/wood‐flour composite foams with high void fraction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3139–3150, 2003     

Influence of a Rare-Earth Coupling Agent on the Interfacial Interaction of Wood Flour/Polypropylene Composites

Abstract

In this article, the influence of a rare-earth (RE) coupling agent on the interfacial interaction of wood flour/polypropylene composites (WF/PP) was investigated by studying the rheology behavior and the mechanical properties and using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The increased equilibrium torque results implied that the composites had a greater frictional shear force, which probably resulted from strong adhesion at the interface between the WF and PP. The mechanical property results showed that the added RE improved: the tensile strength by 42.6%; the flexural strength by 66.7%; and the impact strength by 92.3%, when compared to the WF/PP composites containing no RE material. According to the DSC results, the addition of the RE decreased the crystallization temperature and melting temperature. These results showed that the RE improved the interfacial adhesion. This was further confirmed by the SEM analysis of the composites.