PVC/木塑复合材料挤出发泡的研究进展

由于木塑复合材料的独特优点,使其需求迅速增长,很多国家正着手建立本国的木塑工业体系。总结了国内外在PVC木/塑复合材料挤出发泡研究上取得的进展,分别从木粉处理、配方、成型工艺及成型设备等关键技术上介绍PVC木/塑发泡复合材料研究取得的成就。并就当前的发展情况,提出了PVC木/塑发泡材料的发展方向。     

PVC/木粉复合材料的发泡研究

采用PVC树脂和木粉加入发泡剂制得PVC/木粉发泡复合材料。通过差示量热扫描分析(DSC)考察了偶氮二甲酰胺(AC)、NaHCO3及AC/NaHCO3/PVC稳定剂共混物的热分解特性。研究了木粉的不同粒径、AC发泡剂、NaHCO3、交联剂DCP和ACR的含量对复合材料力学性能的影响。结果表明:通过发泡能有效降低材料的密度;当AC含量为PVC用量的1%,木粉粒径为20目,NaHCO3与AC用量比为1∶1,DCP含量为PVC用量的0.4%,ACR含量为PVC用量的8%,所得的发泡复合材料综合性能较好。     

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。     

PVC/木粉发泡复合材料的性能影响因素分析

PVC（PW）/木粉复合材料的研制？生产和应用对于寻求实体木材的替代品和利用木材加工残余物具有重要意义,也是塑料回收再生利用的有效途径之一。PVC（PW）/木粉复合材料的优点主要是力学强度高、耐强酸碱腐蚀性强和经济环保。对复合材料的性能影响因素进行了分析,并对PVC/木粉复合材料研究和探索的方向和趋势进行概述。     

木粉/PP发泡复合材料的性能研究

本文采用注塑发泡法制备了木粉/PP发泡复合材料。考察了发泡剂用量、木粉含量对发泡复合材料性能的影响。结果表明,发泡后的复合材料密度明显降低,发泡剂含量为1.5%时发泡复合材料的密度降低了17%,冲击强度提高了20%。木粉含量增加小幅提高了发泡复合材料的密度,降低了其力学性能。     

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。     

CPE对发泡PVC/木粉复合材料熔体流变性能的影响

采用旋转流变仪,应用小振幅流变测试法研究了抗冲击改性剂氯化聚乙烯（CPE）对发泡聚氯乙烯(PVC)/木粉复合材料熔体流变性能的影响。实验结果表明：角频率（ω）在0.1～100 rad/s之间时,随ω的增大,发泡PVC/木粉复合材料熔体的复数黏度（η*）降低,表现出"剪切变稀"效应,熔体的储能模量（G′）和损耗模量（G〞）随ω的增大而增加;加入5份CPE时,复合材料熔体的G〞明显提高,G′变化幅度较小,熔体的η*增加,促进了PVC的凝胶化;继续增加CPE的用量到10份,发泡PVC/木粉复合材料熔体的G〞和G′降低,η*也降低;随着ω的增加,加入CPE使样品的损耗角正切明显降低,熔体的弹性响应增加。加入10份CPE时,发泡PVC/木粉复合材料的冲击强度提高20 ％。     

稻糠粉/木粉并用对PVC基木塑复合材料的性能影响

采用稻糠粉和木粉填充聚氯乙烯(PVC)基木塑复合材料,研究并比对了复合体系的力学性能、耐水性、使用温度和加工性能的影响。结果表明:稻糠粉/木粉并用比增加,可以提高复合材料的拉伸强度、冲击强度和使用温度,改善其耐水性和加工流动性;当稻糠粉/木粉用量比为50/50时,复合材料的综合性能最佳,拉伸强度、冲击强度和维卡软化点温度分别达到最大值44.3MPa、15.2kJ/m2和117℃。     

无机阻燃剂对PVC/木粉复合材料性能的影响

分别采用A1(OH)3、ZB以及Sb2O3等无机阻燃剂对PVC/木粉复合材料改性,研究不同的阻燃剂配方及阻燃剂含量对PVC/木粉复合材料阻燃性能和力学性能的影响。结果表明:随着A1(OH)3,ZB以及Sb2O3添加量的增加,PVC/木粉复合材料的氧指数(LOI)呈逐渐增大的趋势。Sb2O3阻燃效率最高,当添加量为9份时,氧指数达到35.2%;无机阻燃剂的加入普遍降低了PVC/木粉复合材料的冲击韧性,但对拉伸强度起到了一定的增强作用。     

木粉增强木质素／环氧树脂复合材料的制备与力学性能

将玉米秸秆酶解木质素和双酚A环氧树脂共混,利用低相对分子质量聚酰胺作为同化剂,采用热压工艺制备了一种木粉增强的交联型木质素,环氧树脂复合材料,研究了热压温度、热压压力以及木粉的加入对复合材料力学性能的影响。研究结果表明,随着热压温度和热压压力的增加,木粉增强木质素,环氧树脂复合材料的弯曲强度和冲击强度均先升高而后降低,在120℃热压温度、8MPa热压压力下复合材料的力学性能达到最佳。随着木粉含量的增加,复合材料的弯曲强度和冲击强度均升高;木粉的粒径也对复合材料的力学性能有较大影响;综合考虑复合材料的力学性能,优选加入40—80目的木粉,木粉的含量为20％。     

聚氯乙烯/木粉复合材料的研究进展

综述了近年来国内外聚氯乙烯（PVC）/木粉（WF）复合材料的研究进展,对新型的行星辊轮双螺杆挤出机、带有干燥器的锥形双螺杆挤出机以及能直接将木粉输送到挤出机中的"WoodTruderTM"挤出系统等新型设备和工艺进行了介绍,对PVC/WF复合材料中使用的润滑剂、冲击改性剂、增塑剂、相容剂等助剂的研究进展进行了总结,并对PVC/WF复合材料的微发泡工艺和环保性能进行了介绍和评述,在此基础上对PVC/WF复合材料的发展趋势进行了展望。     

影响聚丙烯基木塑复合材料力学性能因素

研究了偶联剂、相容剂、木粉用量和木质填料种类对以聚丙烯（PP）为基体树脂制备小塑复合材料力学性能的影响。结果表明，以硅烷偶联剂处理木粉或直接加入相容剂均使复合材料力学性能得到提高；木粉用量的提高使复合材料冲击强度下降，弯曲强度、弯曲模量、拉伸强度则大幅提高；在分别以粒径为0．14mm木粉和0．22mm木粉、竹粉、花生壳粉、稻壳粉制备复合材料，以粒径为0．14mm木粉与PP制备的复合材料力学性能最好。     

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.     

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.     

Effect of Wood Fibers on the Rheological and Mechanical Properties of Polystyrene/Wood Composites

The effects of wood fibers on the rheological and mechanical properties of polystyrene/wood (PS/wood) composites were investigated. The composites with different ratios of PS and wood were prepared by means of internal mixer and, additionally, two different sizes of the wood particles were used, such as ～100 and ～600 µm. The rheological properties were studied using capillary rheometer, apparent shear rate, apparent shear stress, apparent viscosity, power law index, and flow activation energy at a constant shear stress were determined. The rheological results showed that the shear stress–shear rate variations obeyed a power law equation, and the composites exhibited shear thinning. The flow activation energy of the composites increased with the addition of wood particles. Mechanical results showed that stress at break of the composites was higher than that of pure PS, whereas the strain at break and impact strength of the composites were lower than that of PS. In addition, the mechanical properties of the present composites were improved when the small size of wood particles were incorporated.     

PVC/WF复合发泡材料的研究

采用一步模压法制备聚氯乙烯/木粉(PVC/WF)复合发泡材料,研究木粉(WF)的预处理、用量及粒径对PVC/WF复合发泡材料力学性能、尺寸稳定性、密度、吸水性及吸油性能的影响,并通过扫描电镜(SEM)对其泡孔结构进行分析.结果表明:WF经预处理,PVC/WF复合发泡材料拉伸强度有所增强,密度和吸水率略有减小,吸油性尤明显变化,耐热性稍有降低;随着WF粒径的增加,PVC/WF复合发泡材料的密度、吸水率、吸油率和线性收缩率均增大,拉伸强度从1.25MPa增大到1.78 MPa,断裂伸长率随之减小;随着WF含量增加,PVC/WF复合发泡材料密度和吸油率均明显增加,拉伸强度也随之增大,线性收缩率减小,吸水率先增大后减小,WF质量分数10%时吸水率最大.     

不同相容剂对PP/木粉复合材料力学性能的影响

研究了3种相容剂和3种偶联剂分别在单独使用和配合使用情况下对PP/木粉(质量比50/50)复合材料力学性能的影响。相容剂PP-g-MAH、PE-g-MAH、SBS-g-MAH单独使用发现:SBS-g-MAH使材料综合性能最好,PE-g-MAH对冲击强度提高明显。硅烷偶联剂HP-172在提高复合材料的冲击强度和拉伸强度方面较好,HP-174对弯曲性能改善较好,钛酸酯偶联剂NDZ-201仅对弯曲模量有所改善,而对其它性能改善不大。相容剂与偶联剂共同使用具有协同效应,其中HP-174与SBS-g-MAH并用效果最好,使各项力学性能都有提高。     

不同木粉比例PVC木塑界面的介观模拟以及力学性能预测

研究了DPD(耗散粒子动力学)方法模拟不同木粉比例的PVC木塑中木粉的分布状况,从介观尺度表征了木粉在材料中的聚集状态,通过木粉在木塑材料中的分布情况预测高木粉填充木塑材料的力学性能,并与试验值进行对比,得出当木粉含量达到15%~31.5%可以达到力学性能最优区间。     

PP/微球复合材料的发泡行为及力学性能

选用PP(EPS30R)、PP(K9928)为基体材料,分别加入EK405、EK406微球母粒,在二次开模条件下制备微发泡PP/微球复合材料,研究不同特性树脂和微球母粒对PP/微球复合材料发泡行为及力学性能的影响规律。结果表明:微球母粒EK406适合于PP/膨胀微球复合材料的发泡,发泡倍率达12%,泡孔平均直径和泡孔密度分别为29.94μm、7.93×106个/cm3,能够获得泡孔细小、均匀而致密的微发泡聚丙烯材料。熔体指数低的PP材料适合于微球发泡,发泡质量较好,综合性能理想,拉伸和冲击强度分别为18.52 MPa、13.18 kJ/m2,比强度达到23.03。