超分散剂对塑木复合材料性能的影响

以松香、二乙撑三胺和12-羟基硬脂酸为原料,合成了松香超分散剂(RDH)。用RDH对高密度聚乙烯塑木复合材料进行改性,研究了RDH对塑木复合材料力学性能、热性能等的影响,并用扫描电镜(SEM)观察复合材料的冲击断面形貌。结果表明:经RDH改性后,塑木复合材料的冲击强度和弯曲强度分别提高了35.2%和21.5%。RDH的加入改善了复合材料的热稳定性,储能模量提高,损耗因子降低。     

棉秆塑木复合材料的制备及性能研究

以棉秆粉和回收聚乙烯为原料、钛酸酯为偶联剂,采用热压法制备了棉秆塑木复合材料,利用正交试验法探讨了棉秆粉含量、热压温度和保温时间对塑木复合材料性能的影响,并通过物理力学性能测试单独考察了棉秆粉含量对塑木复合材料性能的影响。正交试验法的结果表明:棉秆粉含量对复合材料的弯曲强度、弹性模量和吸水率影响最大,热压温度和保温时间对复合材料的弯曲强度和弹性模量影响较大,对吸水率影响不大;当棉秆粉含量为40%、热压温度为160℃、保温时间为10 min时,塑木复合材料具有最优的综合性能。物理力学性能测试结果表明:复合材料的弯曲强度和弹性模量随棉秆粉含量的增加均呈现先增大后减小的趋势,在棉秆粉含量为40%时均达到最大值;吸水率随棉秆粉含量的增加而增大。     

低发泡塑木复合材料的研制

以木粉、PE树脂等为原料，研制了发泡塑木复合材料。对低发泡塑木复合材料生产的基本方法进行了介绍；对该复合材料的密度、吸水性、力学性能进行了测试。结果表明：该复合材料的密度与原木十分接近；具有极佳的防水性能，含水率不超过2％；拉伸强度、弯曲强度、冲击强度、压缩强度、拔钉强度等力学性能能够满足所生产的产品性能的需要。     

聚磷酸铵阻燃塑木复合材料的研究

以Ⅱ型聚磷酸铵为阻燃剂制备了阻燃塑木复合材料并通过水平燃烧、成炭量等评价了材料的综合性能。研究表明,APP的添加有效改善了塑木复合材料的水平燃烧性能,使材料的水平燃烧时间增加,水平燃烧速率下降。当APP的添加量为20％时,材料水平燃烧未烧至25mm处。塑木复合材料的成炭量较未添加时的23．7％,提高了一倍,氧指数提高T29％,表现出良好的阻燃性能。随着APP添加量的增加材料的拉伸强度和冲击强度有所下降,弯曲强度、弯曲模量则增加。     

废旧PE/木粉/粉煤灰复合材料的制备与辐射改性研究

以废旧聚乙烯、木粉和粉煤灰为主要原料,添加一定量的加工助剂,经高温模压成型制备了一种新型塑木复合材料,并采用辐射交联技术对复合材料进行改性;研究了木粉、粉煤灰和辐射剂量对复合材料物理机械性能的影响。结果表明:该复合材料经60 kGy辐射后,其弯曲强度、拉伸强度和冲击强度分别提高了11.2%、37.5%和12.1%,材料的摩擦系数也降低了12.6%。     

塑木材料常用相容剂性能分析

介绍了氯化聚乙烯体系等四种常用的塑木材料相容剂对塑木材料的冲击强度、弯曲强度和弯曲模量及热变形温度等指标的影响等。     

PVC/锯末塑木材料的研制

以锯末和PVC胶粘剂为主要原料，用高速混合机制备了PVC／锯末塑木材料，并通过平板硫化机热压成型，制备出了新型的PVC／锯末塑木板材；测试了塑木板材的拉伸强度，弯曲强度，冲击强度，拉伸弹性模具，弯曲弹性模量等力学性能，讨论了增塑剂和胶粘剂用量对塑木板材性能的影响，实验结果表明：随增塑剂用量的增大，PVC／锯末塑木板材的刚性下降，韧性升高；随胶粘剂用量的增大，PVC／锯末塑木板材的力学性能和耐水性均有提高。     

塑木地板的弯曲疲劳/蠕变性能研究

对塑木地板进行弯曲性能测试,选取25%、50%和75%3种应力水平进行疲劳/蠕变试验.结果表明:从断面结构来看,空心型塑木地板的疲劳/蠕变性能最好,实心型次之,开口型最差;在交变栽荷最大值为塑木复合材料破坏载荷的50%、75%时,其疲劳/蠕变断裂曲线为三段式曲线,随着最大栽荷保持时间的增加,蠕变加剧材料塑性变形.导致材料应变增大、迅速断裂;在25%和50%应力水平作用后,材料的剩余弯曲强度为原来的96%～98%.     

松香树脂对天然橡胶/聚酯纤维复合材料界面黏结性能的影响

研究了松香树脂对天然橡胶硫化性能、交联密度以及天然橡胶/聚酯纤维复合材料界面黏结性能的影响,阐述了松香树脂改善天然橡胶/聚酯纤维复合材料界面黏结强度的机理。结果表明,向天然橡胶中加入松香树脂可以延长其焦烧时间和提高交联密度;加入松香树脂可以明显改善天然橡胶/聚酯纤维复合材料的黏结强度,当松香树脂用量为3份时,复合材料的黏结强度达到最佳值。     

空心玻璃微珠填充改性PS复合材料的性能

采用熔融共混挤出的方法,制备不同空心玻璃微珠含量的PS复合材料,研究空心玻璃微珠对复合材料力学性能和热稳定性的影响.结果表明:经过表面处理的空心玻璃微珠与PS的相容性显著提高,空心玻璃微珠质量含量为5%时,复合材料获得最大拉伸强度、弯曲强度和冲击强度.     

Novel coupling agents for PVC/wood‐flour composites *

Effective interfacial adhesion between wood fibers and plastics is crucial for both the processing and ultimate performance of wood–plastic composites. Coupling agents are added to wood–plastic composites to promote adhesion between the hydrophilic wood surface and hydrophobic polymer matrix, but to date no coupling agent has been reported for PVC/wood‐fiber composites that significantly improved their performance and was also cost‐effective. This article presents the results of a study using chitin and chitosan, two natural polymers, as novel coupling agents for PVC/wood‐flour composites. Addition of chitin and chitosan coupling agents to PVC/wood‐flour composites increased their flexural strength by ～20%, their flexural modulus by ～16%, and their storage modulus by ～33–74% compared to PVC/wood‐flour composite without the coupling agent. Significant improvement in composite performance was attained with 0.5 wt% of chitosan and when 6.67 wt% of chitin was used. J. VINYL ADDIT. TECHNOL., 11:160–165, 2005. © 2005 Society of Plastics Engineers     

PP-g-MAH增容改性木粉/PP复合材料的性能研究

以马来酸酐接枝聚丙烯 (PP-g-MAH) 为相容剂,聚丙烯 (PP) 为基体,通过熔融共混法制备了木粉/PP复合材料。研究了 PP-g-MAH 用量对复合材料力学性能及吸水性能的影响; 采用扫描电镜 (SEM) 观察了复合体系的冲击断面形貌。结果表明: 当 PP-g-MAH 的质量分数为 4%时,可以提高添加 35 份木粉复合材料体系的拉伸强度及弯曲强度,比未添加相容剂的分别提高了 49.4%和 16%,而缺口冲击强度仅下降了 9%。SEM 观察证实: PP-g-MAH 的加入有利于提高木粉与 PP 基体的界面相互作用。从吸水率来看,木粉/PP 复合材料的吸水率保持在 0.22% 以下,远低于纯木材。     

Mechanical properties of wood plastic composite panels made from waste fiberboard and particleboard

The possibility of producing wood‐plastic panels using a melt blend/hot press method was studied in this research. The studied panels were compared with conventional medium density fiberboard (MDF) and particleboard (PB) panels. Wood‐plastic panels were made from high density polyethylene (as resin) and MDF waste and PB waste (as natural fiber) at 60, 70, and 80% by weight fiber loadings. Nominal density and dimensions of the panels were 1 g/cm³ and 35 × 35 × 1 cm³, respectively. Mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistances, and impact strength were studied. Results indicated that the mechanical properties of the composites were strongly affected by the proportion of the wood flour and polymer. Maximum values of flexural modulus of wood plastic panels were reached at 70% fiber content. Flexural strength, screw and nail withdrawal resistance, and impact strength of wood plastic composites declined with the increase in fiber content from 60 to 80%. This was attributed to the lack of compatibility between the phases. The produced panels outperformed conventional PB panels regarding their mechanical properties, which were acceptable when compared with MDF panels as well. The best feature in the produced panels was their screw withdrawal resistance, which is extremely important for screw joints in cabinet making. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Mechanical properties of biorenewable fiber/plastic composites

Plastic fiber composites, consisting of polypropylene (PP) or polyethylene (PE), and pinewood, big blue stem (BBS), soybean hulls, or distillers dried grain and solubles (DDGS), were prepared by extrusion. Young's modulus, tensile and flexural strengths, melt flow, shrinkage, and impact energy, with respect to the type, amount, and size of fiber on composites, were evaluated. Young's moduli under tensile load of wood, BBS, and soybean‐hull fiber composites, compared with those of pure plastic controls, were either comparable or higher. Tensile strength significantly decreased for all the PP/fiber composites when compared with that of the control. Strength of BBS fiber composites was higher than or comparable to that of wood. When natural fibers were added there was a significant decrease in the melt flow index for both plastic/fiber composites. There was no significant difference in the shrinkage of all fiber/plastic composites compared to that of controls. BBS/PE plastic composites resulted in higher notched impact strength than that of wood or soybean‐hull fiber composites. There was significant reduction in the unnotched impact strength compared to that of controls. BBS has the potential to be used as reinforcing materials for low‐cost composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2484–2493, 2004     

木粉对PVC木塑复合材料力学性能影响

采用电镜扫描观察了3种木粉的纤维细胞尺寸及其木粉微观形态。研究了木粉粒度、微观特性以及木粉添加量对了聚氯乙烯（PVC）木塑复合材料力学性能的影响。结果表明，木粉表面裸露的微细纤维增加和粒度减小，有助于提高木塑复合材料力学强度；加入少量木粉使木塑复合材料力学性能降低，但随着木粉添加量的增大，木塑复合材料的抗弯性能和拉伸强度上升；木塑复合材料的冲击强度随木粉含量增加而下降。     

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     

Effect of processing method on surface and weathering characteristics of wood–flour/HDPE composites

Wood–plastic lumber is promoted as a low‐maintenance high‐durability product. When exposed to accelerated weathering, however, wood–plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood–plastic composites lead to different surface characteristics, which can influence weathering. In this study, 50% wood–flour‐filled high‐density polyethylene (HDPE) composite samples were injection molded, extruded, or extruded and then planed, to remove the manufacturing surface characteristics. Fourier transform infrared spectroscopy was used to chemically show the difference in surface components. The samples were weathered in a xenon‐arc weathering apparatus for 1000, 2000, and 3000 h and analyzed for color fade and loss of flexural modulus of elasticity and strength. Final color (lightness) after weathering was not dependent on the manufacturing method. However, the manufacturing method was related to mechanical property loss caused by weathering. Composites with more wood component at the surface (i.e., planed samples) experienced a larger percentage of total loss in flexural modulus of elasticity and strength after weathering. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1021–1030, 2004     

Effects of alkaline and silane treatments on the water‐resistance properties of wood‐fiber‐reinforced recycled plastic composites

The water‐resistance properties of wood‐fiber‐reinforced recycled plastic composites (WRPCs) prepared from postconsumer high‐density polyethylene (HDPE) and wood fibers from saw mills were studied. Three methods consisting of an alkaline method (AM), a silane method (SM), and a combination of the alkaline and silane methods (ASM) were used to modify the wood fibers. The effects of fiber/matrix mix ratio and surface treatment on the moisture content, thickness swelling, and flexural strength change of the WRPCs, before and after immersion in 60°C water for 8 weeks, were studied and analyzed. The flexural fractured surfaces of the WRPCs before and after immersion in hot water were examined, and the fracture mechanism of the WRPCs was discussed. The results showed that the different surface treatments of the wood fibers had significant effects on the moisture content, thickness swelling, and flexural strength of the WRPCs after a long immersion time in hot water. For WRPCs treated by ASM, the moisture content was the lowest, the thickness swelling was at a minimum, and the flexural strength was the highest. Higher water absorption of composites with fiber treated by the AM or SM methods, as compared to those treated by ASM, could be attributed to the incomplete adhesion and wettability between the wood fibers and the polymer matrix, which may have caused more gaps and flaws at the interface. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

纳米TiO_2含量对PVC/稻壳粉木塑复合材料性能的影响

将纳米TiO_2、稻壳粉、聚氯乙烯(PVC)和稳定剂等按一定比例混合,用挤出成型法制备PVC/稻壳粉木塑复合材料。考察纳米TiO_2添加量对PVC/稻壳粉木塑复合材料性能的影响。实验结果表明,随着纳米TiO_2含量的增加,木塑复合材料的力学性能、防水性能和热稳定性呈现先增加后降低的趋势,但木塑复合材料的表面颜色却随着纳米TiO_2含量的增加而逐渐变浅。当纳米TiO_2含量为1.00份时,木塑复合材料的综合性能最好,与未添加纳米TiO_2的木塑复合材料相比,其拉伸强度、冲击强度和弯曲强度分别提高了40.6%,62.2%和19.7%,8 d的吸水率从2.5%降低为1.6%,表面接触角从78.5°增加到82.1°,800℃时的残炭率从21.1%提高到29.5%。