Effect of chemical modification on the properties of wood/polypropylene composites

对以铝酸酯为偶联剂对木粉进行表面改性处理后制备的木粉/聚丙烯复合材料的力学性能和形态学特征进行了研究。结果表明:铝酸酯偶联剂可以增加木塑复合材料的抗冲击强度,但会对复合材料的抗拉强度和抗弯强度造成负面的影响。对木塑复合材料的动态力学性能和微分扫描热量分析研究表明,以铝酸酯作为偶联剂,对木塑复合材料的储存模量和损失模量有少许增加,同时可降低材料的熔点和熔解热。利用扫描电镜观察木塑复合材料的木材与塑料界面发现,经铝酸酯处理过的木材与聚丙烯复合界面之间具有更好的相容性。这些研究结果表明,在木塑复合材料制造过程中利用廉价的铝酸酯作为木材化学改性剂,对改善复合材料的性质同样起作良好的作用。图6 表2 参16。     

偶联剂对木塑复合材料界面相容性的影响

采用单因子试验法重点研究了钛酸酯和铝酸酯作为木塑复合材料的偶联剂对木塑复合材料界面相容性的影响, 通过ESEM和FTIR等现代分析手段,揭示了两种偶联剂的作用机制和影响规律。研究表明:加入钛酸酯或铝酸酯可改善木塑复合材料的力学性能,且随着钛酸酯或铝酸酯用量增大,木塑复合材料力学性能呈先增大后减小的趋势。加入钛酸酯使木塑复合材料主要力学性能明显增强,加入铝酸酯则略有改善。     

麦秸/纤维状聚丙烯复合材料的性能

以麦秸和纤维状聚丙烯塑料(PP)为原料,马来酸酐接枝聚丙烯(MAPP)作为偶联剂,采用平压法压制麦秸/聚丙烯复合材料,研究聚丙烯用量和麦秸碎料目数对木塑复合材料性能的影响.结果表明:随着纤维状PP添加量的增加,板材各项性能均有不同程度的提高书MAPP显著改善了板材的界面结合效果.     

偶联剂对木/塑复合材料性能的影响

采用钛酸酯、铝酸酯和铝钛复合偶联剂对木粉进行表面处理,研究对木粉/PVC复合材料综合性能的影响.SEM电镜扫描发现,铝钛复合偶联剂OL-AT1618能促进木粉在PVC基体中均匀分散,改善两相界面相容性,从而显著提高复合材料的物理力学性能和加工性能.     

铝酸酯偶联剂对竹塑复合材料界面性能的影响

研究铝酸酯作为竹粉和聚己内酯的偶联剂对竹塑复合材料界面性能的影响.通过IR、X射线衍射(XRD)等现代分析手段揭示了偶联剂与竹粉的作用以及较佳的处理时间,并用转矩流变仪和示差扫描量热分析(DSC)考察偶联剂对竹粉和聚己内酯相容性的影响.结果表明,在一定的时间内,高速搅拌和偶联剂一起使竹纤维的有序结构遭到破坏,偶联剂的添加量为 1.6 %(相对竹粉用量)时,复合材料具有最好的加工性能.     

蔗渣纤维增强聚丙烯复合材料的力学性能研究

利用甘蔗渣纤维作为增强剂,回收的聚丙烯塑料作为基体,并添加MAPP为偶联剂,通过熔融混合、注射成型法制成蔗渣纤维/PP 复合材料,研究蔗渣纤维和偶联剂对复合材料静态及动态力学性能的影响。结果表明：与PP相比,添加了蔗渣纤维和MAPP后,除抗拉强度外,复合材料的静态力学强度有所提高;复合材料的储能模量和损耗模量增加,而损耗因子降低;蔗渣纤维/PP复合材料的玻璃化转变温度Tg为61.8℃。     

改性白泥/PVC复合材料的研究

以白泥和PVC为主要原料,采用铝酸酯偶联剂对白泥进行表面处理,研制了改性白泥/PVC复合材料。优化了偶联剂用量和白泥用量,当偶联剂用量为0.5份(相对于白泥用量)、白泥用量25份(相对于PVC用量)时,复合材料的冲击强度、拉伸强度、弯曲强度和维卡软化温度均较高。研究发现改性白泥对PVC有明显增韧增强作用,通过对改性白泥的红外光谱和复合材料的微观形态分析,阐述了偶联剂改性白泥增韧增强PVC材料的机理。     

混炼工艺参数对木/塑复合材料性能的影响

通过混炼工艺进行复合材料配方试验，研究木／塑混和比、偶联剂种类和加入比例以及混炼时间等工艺参数对复合材料性能的影响。结果表明；加入偶联剂可使材料的主要强度指标增加；混炼时间对材料性能影响不显著。     

MAPP改性木粉/聚丙烯复合材料的物理力学性能

木塑复合材料的界面相容性是决定其性能的关键因素,通过添加偶联剂的方法能够改善其界面相容性,从而提高其性能。通过测定毛白杨木粉/聚丙烯复合材料的物理力学性能来研究木粉含量和偶联剂添加量对木塑复合材料物理力学性能的影响,为进一步研究木塑复合材料的界面相容性提供理论依据。研究结果表明:随着木粉含量的增加,复合材料的物理力学性能下降,并且在高木粉含量阶段影响显著;高木粉含量复合材料的性能较差,添加MAPP能显著改善其物理力学性能。     

桦木/聚丙烯挤出复合工艺技术研究

以桦木锯屑和聚丙烯为原料，马来酸酐（MAPP）为偶联剂，采用SJSH30／SJ45双阶单双螺杆挤出机组制作木材纤雏／聚丙烯复合材料。试验结果表明，随着桦木锯屑加入量的增加，复合材料强度呈下降趋势，当偶联荆的添加量为5％时，除桦木与聚丙烯塑料比例为30：70复合材料的弹性模量有下降外，其余材料均表现出力学强度和弹性模量的显著增强；当偶联剂的添加量进一步增大到8％时，复合材料弹性模量的增加趋缓，因此，确定偶联剂的添加量为5％。     

Preliminary study of the effects of EVA coupling agents on properties of wood-plastic composites

As a hot-melt adhesive, ethylene-vinyl-acetate (EVA) has been used in many industrial applications. But studies of the application of EVA in wood-plastic composites (WPC) are relatively few, so we have investigated the proposition of whether EVA is a suitable coupling agent for WPC or not. The results show that EVA with 8% VA is not a suitable coupling agent, because it reduces the mechanical properties of WPC without any significant effect on its physical properties. With an increase in the amount of wood powder, the mechanical properties of WPC decrease and the ability of water absorption of WPC increases.     

Preliminary study of viscoelastic properties of MAPP-modified wood flour/polypropylene composites

Viscoelastic properties of maleated polypropylene (MAPP)-modified wood flour/polypropylene composites (WPC) were investigated by both a compression stress relaxation method and dynamic mechanical analyses (DMA). Three wood to polymer ratios (40:60, 60:40, and 80:20) and five MAPP loading levels (0, 1, 2, 4 and 8%) were used to study their effects on the viscoelastic properties of MAPP-WPC. The results show that: 1) higher wood to polymer ratio corresponds to higher stress relaxation levels for unmodified WPC. The modification with MAPP has an obvious effect on the stress relaxation of MAPP-WPC at higher wood to polymer ratios (60:40 and 80:20), but almost no effect at the 40:60 wood to polymer ratio. The optimal MAPP loading level for the wood to polymer ratio of 60:40 appears at 1%; 2) the storage modulus reaches its maximum at a MAPP loading level of 1% for wood to polymer ratios of 40:60 and 60:40, while for the 80:20 wood to polymer ratio, a higher storage modulus is observed at higher MAPP loading levels, which is quite consistent with the stress relaxation results. The results suggested that a suitable loading level of MAPP has a positive effect on the viscoelastic properties of WPC at higher wood to polymer ratios. Excessive MAPP loading would have resulted in adverse effects.     

偶联剂对木塑复合材料拉伸性能与热膨胀性能的影响

以高密度聚乙烯(HDPE 6761)为基体,松木(Pine)粉为增强材料,以MAPE(EpoleneG2608)和MAPP(ExxelorVA1840)为偶联剂采用注塑法制备WPC,测定了不同配比WPC的热膨胀性能与拉伸性能,结果表明:在没有加入MAPE只加入木粉的情况下,WPC的拉伸强度较没有加入任何助剂的HDPE有所下降;偶联剂的加入量按不同配比加入对拉伸模量影响不大;对WPC热膨胀系数主要的影响因素应该是木粉的加入量及塑料基体的种类。     

汽车用木粉/聚丙烯复合板的研制

通过气味检测、红外光谱和热失重法,分析出木粉/聚丙烯复合材料产生刺激性气味的原因在于材料的热稳定性较差;应用碱处理、预涂偶联剂、掺入吸附剂和增容剂等方法对木粉进行预处理,测试结果表明,采用碱处理木粉压制的WPC,其气味等级可达到上海某汽车制造企业PV 3900标准3.0级要求.     

Preparation of acetylated wood meal and polypropylene composites II: mechanical properties and dimensional stability of the composites

Acetylated wood meals of Sugi (Cryptomeria japonica D.Don) wood were prepared by mechanochemical processing using a high-speed vibration rod mill. Weight percent gain (WPG) of the acetylated wood meals ranged from 7.0 to 35.5 %. Wood–plastic composites (WPCs) containing 50 % acetylated woods were produced by an injection molding technique. The polymer matrix used was polypropylene homopolymer. Maleic anhydride-grafted polypropylene (MAPP) was also used as a compatibilizing agent. The mechanical properties of WPCs in bending and tensile tests were independent of WPG of acetylated wood meals, and the test values for WPCs containing acetylated wood meals were lower than that of unmodified wood meal. The use of MAPP increased bending and tensile strength, but no effect on bending modulus was found. An increase in WPG significantly decreased water absorbability and thickness swelling of WPCs as measured by dimensional stability tests. These results demonstrated that mechanochemical processing is a promising technique for preparing WPC material with improved dimensional stability. The future challenge is to inhibit the decreases in mechanical properties of WPCs containing acetylated wood meals.     

木粉/PVC复合材料挤出流动性的影响因素

研究木粉的粒径、添加剂的种类及配比等因素,对木塑复合材料挤出流动性的影响.结果表明:木粉粒径越小,复合物料在挤出过程中的流动性能越差,所制备的木塑复合材料色差越大,且产品材色越深.综合考虑加工特性和制品材色,宜选用木粉粒径45～60目；并添加稀土热稳定剂及铝酸酯偶联剂,可以提高物料的挤出流动性.     

Impact of coupling agent on properties of wood-plastic composite

The impact of two coupling agents, maleic anhydride (coupling agent 1) and isocyanate (coupling agent 2) on the properties of wood-plastic composites (WPC) was studied. Wood-plastic composites were made with coupling agents 1 and 2 and properties were tested under the condition that the ratio of wood fiber to thermoplastic polymer was 7:3, target density was 0.7 g/cm³, press temperature was 175°C, press time was 8 min, and adding amount of coupling agent 2%. Results show that coupling agent 2 was superior to coupling agent 1 and had great effect on the physical and mechanical properties of WPC. When using the same coupling agent, the impact on their properties varied with different thermoplastic polymers. Translated from China Forest Products Industry, 2006, 33(4): 30–32 [译自: 林产工业]     

木塑复合缓冲包装材料发泡及其界面的研究动态

在详细论述国内外木塑复合缓冲包装材料研究进展的基础上,分析木塑复合缓冲包装材料的发泡机理、工艺条件和改善木纤维／塑料的界面相容改性的方法。指出气泡成核阶段的泡体质量控制、发泡剂复配比例、工艺条件选择、界面相容改性等是木塑复合缓冲包装材料研究中的关键问题。