微发泡木塑复合材料的研究进展

针对PE／木纤维、PVC／木纤维、PP／木纤维、PS／木纤维四种微发泡木塑复合材料体系，介绍了国内外在性能改进及工艺设备方面取得的一些进展。分析了目前该领域的现状及今后的发展方向，并展望了微发泡木塑复合材料未来的应用领域及市场前景。     

木粉对PVC发泡木塑复合材料性能的影响

采用PVC树脂和木粉加入发泡剂制得PVC/木粉发泡复合材料。本文对木粉进行了热重分析,考察木粉粒径及含量对PVC/木塑发泡材料性能的影响,考察了木粉含量对发泡、熔融指数、转矩加工流变性以及耐候性的影响。结果表明:TG分析表明PVC/木塑复合材料加工的最佳温度200℃左右。随着木粉粒径的减小,PVC/木粉复合材料的冲击强度和弯曲强度出现先上升后下降的趋势,100目木粉,力学性能最好。随着木粉用量的增加,体系的拉伸强度、冲击强度和弯曲强度均呈降低的趋势,材料的发泡效果变差,流动性、稳定性、耐候性变差,因此PVC木塑复合材料应该控制其木粉含量。     

PVC/木粉复合材料挤出发泡成型的研究

介绍木塑复合材料挤出发泡成型的发展和加工难点,针对聚氯乙烯(PVC)／木粉复合材料挤出发泡的成型方法,从原料、配方、工艺、设备等方面作了详细分析。简述了PVC／木粉复合材料挤出发泡制品的性能及影响制品性能的主要因素。     

PVC／木粉复合材料挤出发泡成型的研究

介绍木塑复合材料挤出发泡成型的发展和加工难点，并针对聚氯乙烯（PVC）／木粉复合材料挤出发泡的成型方法，从原料、配方、工艺、设备等方面作了详细分析。最后简述了PVC／木粉复合材料挤出发泡制品的性能及影响制品性能的主要因紊。     

不同种类木纤维对PE基微孔发泡木塑复合材料的性能影响

采用挤出、注塑成型工艺制备PE基木纤维/塑料微孔发泡复合材料.从不同木纤维的种类对PE基木纤维/塑料微孔发泡复合材料的密度、冲击强度、弯曲强度、拉伸强度进行研究.实验结果表明:以木粉为填料所制得的木塑微孔发泡复合材料密度最佳;竹粉和秸秆粉的冲击强度都优于木粉,且竹粉所制得的复合材料具有最佳的力学性能.     

木粉填充PVC树脂复合材料力学性能的研究

木塑复合材料主要的发展趋势是木塑复合材料微发泡技术。大型宽幅度较厚的板材制品技术等成套设备及制品成型技术的开发,改善木塑制品应用中存在的诸如密度大、尺寸不能满足实际需要等问题,不断扩大木塑制品的应用领域。通过调节粉料含量的不同、粒径的不同及粉料种类的不同,制备木粉及短纤维/PVC复合材料,进而研究木粉/PVC复合材料的各种性能。实验中粉碎的木屑,在进行实验之前进行烘干,这样有利于实验中对木屑粉碎、筛选。将木粉烘干,除去木屑中可能存在的水分、易挥发成分以及易分解成分,保证加工顺利、制品光亮、色泽正常、制品强度高。随着实验中木粉加入量的增大,复合材料的冲击性能有所下降,木粉含量为45%,冲击性能达到最佳。木粉含量越高,使木塑复合材料的粘结性能和流动性能均变差,因而影响木塑复合材料的拉伸和冲击等力学性能。     

木塑复合材料注塑发泡成型技术的研究

介绍了木塑复合材料注塑发泡成型技术研究的背景和现状,详述了木塑复合材料注塑发泡成型过程中的成型原理、原料的选择及影响成型质量的主要因素.指出木塑发泡复合材料在资源综合利用与环境保护方面有明显优势,近年来受到广泛的关注.     

粉煤灰在PVC木塑结皮发泡建筑模板中的应用研究

介绍以偶联剂活化共混粉煤灰/碳酸钙(PFA/CaCO3)两种填料在生产PVC木塑结皮发泡建筑模板中的应用研究。探讨了共混活化料对PVC木塑结皮发泡复合材料的改性机理,研究了其不同用量的活化料配方对木塑复合材料在加工应用方面及对产品力学性能的影响。结果表明:两种活化料填充生产的PVC木塑结皮发泡板材较一种活化料改性效果显著,在物料的塑化性能、相容性、加工稳定性和产品的综合力学性能都得到了改善和提高。     

改性木粉/PVC复合材料的研究进展

概述了PVC木塑复合材料的发展和背景与性能。简述了木质材料的性质和木粉改性的方法,如物理方法和化学方法。介绍了木塑复合材料的生产流程、成型方法(模压成型、挤出成型、注射成型及其成型设备,讨论了对工艺参数的一些要求。指出目前国内PVC木塑复合材料发展存在的一些问题,并指明了PVC木塑复合材料的应用前景。     

产品开发

正新型木塑复合材料研发前景好新型木塑复合材料如发泡木塑复合材料是将塑料母粒、木粉、填料、发泡剂和各种助剂按一定比例混合,在成型过程中向材料内部引入泡孔而制成。发泡木塑复合材料可克服普通木塑复合材料脆性较大、抗冲击强度较小和材料伸长率较低的缺点,并具有比普通木塑复合材料所用树脂量少、原料成本降低、密度减少,便于运输、施工安装,隔音、隔热和缓冲效果提高等优点,因而成为物流包装等行业代木代塑产品发展的主     

Foaming of rigid PVC/wood‐flour composites through a continuous extrusion process

The effects of chemical foaming agent (CFA) types (endothermic versus exothermic) and concentrations as well as the influence of all‐acrylic processing aid on the density and cell morphology of extrusion‐foamed neat rigid PVC and rigid PVC/wood‐flour composites were studied. Regardless of the CFA type, the density reduction of foamed rigid PVC/wood‐flour composites was not influenced by the CFA content. The cell size, however, was affected by the CFA type, independent of CFA content. Exothermic foaming agent produced foamed samples with smaller average cell sizes compared to those of endothermic counterparts. The experimental results indicate that the addition of an all‐acrylic processing aid in the formulation of rigid PVC/wood‐flour composite foams provides not only the ability to achieve density comparable to that achieved in the neat rigid PVC foams, but also the potential of producing rigid PVC/wood‐flour composite foams without using any chemical foaming agents.     

木粉填充HDPE/PVC复合材料的热稳定性及流变行为

以聚磷酸铵(APP)和Al(OH)3为阻燃剂,通过熔融挤出制备了具有阻燃性能的高密度聚乙烯/聚氯乙烯(HDPE/PVC)基木塑复合材料,研究了PVC对木塑复合材料热稳定性及流变行为的影响。热失重分析结果表明:APP和PVC均可促进木粉成炭,同时提高了HDPE的热稳定性;流变测试结果表明:PVC与木粉的相容性较HDPE要好,并能促进木粉在体系中均匀分散,改善木塑复合材料体系的加工流动性;锥形量热测试结果表明:PVC脱氯、Al(OH)3热分解均吸收大量热量,可降低复合材料的热释放速率与热释放总量。     

Mechanical properties of extrusion‐foamed rigid PVC/wood‐flour composites

This study was conducted to characterize the mechanical properties of extrusion‐foamed neat rigid PVC and rigid PVC/wood‐flour composites by using endothermic and exothermic chemical foaming agents (CFAs). The specific elongation at break (ductility) of the samples was improved by foaming, while the opposite trend was observed for the tensile strength and modulus of the samples, regardless of the chemical foaming agent type. In addition, experimental results indicated that foaming reduced the Izod impact resistance of both neat rigid PVC and rigid PVC/wood‐flour composites but that this reduction was not statistically significant for the composites. A comparison between batch microcellular processing and extrusion foam processing was made, which demonstrated that foams with very fine cells (microcellular processed) exhibit better impact strength than foams with larger cells (extrusion processed with CFAs).     

木粉特性对PVC／木塑发泡材料性能的影响

对木粉进行了热重分析,考察了木粉粒径及表面处理方法对PVC／木塑发泡材料性能的影响。结果表明：采用粒径117μm（120目）、经过硅烷类偶联剂处理的木粉制得的PVC／木塑发泡材料的综合性能较优;相同发泡剂用量下,PVC／木塑发泡材料密度随木粉用量的增加而增大,发泡效果变差。     

Influence of wood fiber size on extrusion foaming of wood fiber/HDPE composites

Foaming of wood fiber/plastic composites (WPC) with a fine‐celled structure can offer benefits such as improved ductility and impact strength, lowered material cost, and lowered weight, which can enhance their utility in many applications. Although a great deal of attention is now being focused on these composites in the scientific literature, there are still numerous aspects of WPC processing that need elucidation. In this context, this article investigates the effects of wood fiber (WF) size on fine‐celled extrusion foaming of WPC in terms of cell size, cell size distribution, and foam density. The effects of WF size and coupling agent content on the viscosity of WPC are also investigated. The experimental results revealed that the small‐sized WF provides a better cell morphology, a smaller cell size, and a better cell uniformity in WPC foams. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

木粉/LDPE复合材料的性能

采用低密度聚乙烯(LDPE)与木粉制得了木粉／LDPE复合材料。研究了木粉用量、表面处理剂种类及用量以及发泡剂用量对复合材料性能的影响；并对化学发泡法减轻复合材料自重的方案做了初步探讨。结果表明：当木粉用量为30份，表面处理剂用量为木粉质量的1．0％时，复合材料的综合性能最佳；添加4份AC发泡剂后，复合材料的密度从0．83g／cm^3降到0．52g／cm^3，化学发泡法可有效减轻材料的自重。     

木粉和发泡剂对PVC基木塑复合发泡材料性能的影响

以木粉、聚氯乙烯树脂、发泡剂等为原料,通过连续挤出得到发泡木塑复合材料。对木粉的热失重、复合发泡材料的泡孔形态、力学性能进行了测试。结果表明:发泡剂用量不应超过1phr;在本实验范围内,木粉粒径的减小会使发泡更容易,材料的力学性能得到改善;木粉粒径对泡孔形态和力学性能的影响有一个最佳范围,即20~80目。     

Density reduction behaviors and cell morphology in extrusion of LLDPE/wood fiber composites with physical and chemical blowing agents

Foamed wood fiber/plastic composites (WPC) with a fine-cell structure offer many benefits compared with the unfoamed WPC, such as the reduced material cost and density, the improved toughness, and the enhanced processability. However, it is extremely challenging to achieve the desired density reduction and obtain a fine-cell structure simultaneously. One of the obstacles is that the volatiles released from the wood fiber (WF) during processing should be suppressed to ensure a fine-cell structure. Linear low-density polyethylene (LLDPE) has a relatively low melting temperature, and it can reduce the processing temperature and suppress volatiles when used as a polymer matrix for foamed WPC. This paper systematically investigates the foamability of LLDPE/WF composites in a continuous foam extrusion, with both a chemical blowing agent and a physical blowing agent (PBA). It turns out that the PBA-based foaming led to a smaller cell size and a narrower cell size distribution. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48829.     

Manufacture of rigid PVC/wood‐flour composite foams using moisture contained in wood as foaming agent

Relatioships between the density of foamed rigid PVC/wood‐flour composites and the moisture content of the wood flour, the chemical foaming agent (CFA) content, the content of all‐acrylic foam modifier, and the extruder die temperature were determined by using a response surface model based on a four‐factor central composite design. The experimental results indicated that there is no synergistic effect between teh CFA content and the moisture content of the wood flour. Wood flour moisture could be used effectively as foaming agent in the production of rigid PVC/wood‐flour composite foams. Foam density as low as 0.4 g/cm³ was produced without the use of chemical foaming agents. However, successful foaming of rigid PVC/wood‐flour composite with moisture contained in wood flour strongly depends upon the presence of all‐acrylic foam modifier in the formulation and the extrusion die temperature. The lowest densities were achieved when the all‐acrylic foam modifier concentration was between 7 phr and 10 phr and extruder die temperature was as low as 170°C.     

Wood/plastic composites co‐extruded with multi‐walled carbon nanotube‐filled rigid poly(vinyl chloride) cap layer

Wood/plastic composites (WPCs) can absorb moisture in a humid environment due to the hydrophilic nature of the wood in the composites, making products susceptible to microbial growth and loss of mechanical properties. Co‐extruding a poly(vinyl chloride) (PVC)‐rich cap layer on a WPC significantly reduces the moisture uptake rate, increases the flexural strength but, most importantly, decreases the flexural modulus compared to uncapped WPCs. A two‐level factorial design was used to develop regression models evaluating the statistical effects of material compositions and a processing condition on the flexural properties of co‐extruded rigid PVC/wood flour composites with the ultimate goal of producing co‐extruded composites with better flexural properties than uncapped WPCs. Material composition variables included wood flour content in the core layer and carbon nanotube (CNT) content in the cap layer of the co‐extruded composites, with the processing temperature profile for the core layer as the only processing condition variable. Fusion tests were carried out to understand the effects of the material compositions and processing condition on the flexural properties. Regression models indicated all main effects and two powerful interaction effects (processing temperature/wood flour content and wood flour content/CNT content interactions) as statistically significant. Factors leading to a fast fusion of the PVC/wood flour composites in the core layer, i.e. low wood flour content and high processing temperature, were effective material composition and processing condition parameters for improving the flexural properties of co‐extruded composites. Reinforcing the cap layer with CNTs also produced a significant improvement in the flexural properties of the co‐extruded composites, insensitive to the core layer composition and the processing temperature condition. Copyright © 2009 Society of Chemical Industry