多异氰酸酯涂覆处理对聚乙烯木塑复合材胶接接头耐水性能的影响

采用多异氰酸酯对聚乙烯木塑复合材料进行表面涂覆处理以改善其胶接性能。利用接触角测试、表面形貌观测以及胶接强度和吸水量测试研究了涂覆表面处理对聚乙烯木塑复合材料胶接接头耐水性能的影响。结果表明,涂覆处理后复合材料的胶接强度和接头耐水性明显提高。水浸后聚乙烯木塑复合材料的表面性质发生了改变,随着水浸时间的延长,表面粗糙度增加,表面接触角下降。长时间水浸下胶接接头的吸水量增加,胶接强度下降。水环境下聚乙烯木塑复合材料中木质纤维的吸水膨胀是造成胶接性能下降的主要原因。     

多异氰酸酯表面处理对木塑复合材胶接耐水性的影响

采用多异氰酸酯对聚乙烯木塑复合材料进行表面处理以改善其胶接性能。利用胶接强度和接触角测试以及SEM、FTIR、XPS等分析方法研究了表面处理对木塑复合材料胶接接头耐水性能的影响。试验结果表明,经打磨并采用多异氰酸酯表面处理后,复合材料的胶接强度和耐水性明显提高。水浸环境下,短期内异氰酸酯处理的木塑复合材料表面变化不大;长期水浸下复合材料的表面逐渐出现微裂纹,表面性质发生改变,胶接强度下降。聚乙烯木塑复合材料中木质纤维的吸水膨胀,是造成水环境下胶接强度下降的主要原因。     

硅烷偶联剂处理木塑复合材胶接接头的耐水性

利用硅烷偶联剂KH560对木粉/聚乙烯复合材料进行表面处理以改善其胶接性能。利用接触角、吸水量、表面形貌以及胶接强度测试等分析方法,研究了硅烷偶联剂处理聚乙烯木塑复合材料胶接接头在水环境中的胶接耐久性能。试验结果表明,机械打磨并偶联剂处理后,聚乙烯木塑复合材表面接触角增加,表面粗糙度增大,胶接强度和耐水性明显提高。偶联剂分子链上环氧基团的"架桥"作用以及甲氧基的憎水作用,是粘接强度和耐水性能提高的主要原因。浸水环境下,聚乙烯木塑复合材料表面粗糙度略有降低;随着浸水时间的延长,表面接触角下降,胶接接头的吸水量增加,胶接强度下降。水环境下聚乙烯木塑复合材料中木质纤维成分的吸水膨胀,是造成胶接强度下降的主要原因。     

偶联剂与等离子体协同表面处理对聚乙烯木塑复合材胶接性能的影响

采用硅烷偶联剂涂覆与等离子体协同处理的方法,对聚乙烯木塑复合材料进行表面处理以改善其胶接性能。研究了硅烷偶联剂浓度、等离子体处理时间、等离子体喷头距试件的处理距离对胶接强度的影响,优化了协同处理工艺。利用接触角测试、红外光谱分析研究了协同表面处理前后材料的表面性质变化,并对胶接接头的耐水性能进行了测试。结果表明:利用偶联剂涂覆和等离子体的协同处理,可以既提高胶接强度,又改善胶接接头的耐水性能。协同处理受偶联剂涂覆和等离子体处理的工艺因素影响较大,选取的优选处理工艺为偶联剂浓度为5%、等离子体处理时间为30s、处理距离为30mm。     

等离子体处理工艺对聚乙烯木塑复合材料表面时效性的影响

利用射流等离子体放电对聚乙烯木塑复合材料进行表面处理以改善其胶接性能。采用接触角测试、FTIR和胶接强度测试等方法,研究了不同等离子体处理工艺对等离子体处理后材料表面时效性的影响。研究结果表明,等离子体处理后的聚乙烯木塑复合材料,随着放置时间的延长,表面接触角和表面极性基团会发生变化,表现出处理时效性。不同工艺的等离子体处理,其处理时效性各不相同;相比之下,机械打磨后再进行等离子体处理的试样处理时效性最小。尽管存在处理时效性,但经射流等离子体处理后的木塑复合材试样放置7d后,仍表现出远大于未处理试样的胶接强度。     

木塑复合材料的胶接技术研究进展

介绍了木塑复合材料的概念与特点,提出了木塑复合材料胶接技术所面临的主要问题,综述了国内外改善木塑复合材料胶接性能的研究现状,总结了胶种优选、表面处理等改善木塑复合材料胶接性能的措施,简述了预测木塑复合材料胶接强度的无损检测手段,展望了木塑复合材料胶接技术研究的发展方向。     

氮气射流等离子体处理时间对PE-WPC表面性质的影响

为解决聚乙烯木塑复合材料制品之间的连接问题,采用氮气射流等离子体放电技术对复合材料表面进行处理,以改善其胶接性能。利用胶接强度测试、接触角测试以及表面红外分析和X-射线光电子能谱分析等手段对材料表面特性进行表征分析,研究氮气射流等离子体处理时间对聚乙烯木塑复合材料表面性质的影响。结果表明:经氮气射流等离子体处理,在材料表面产生大量含氧、含氮极性基团,表面接触角降低,N、O元素的相对含量增加,材料的润湿性能和胶接强度显著改善;且通过调整氮气射流等离子体处理时间,发现材料表面性能随处理时间的延长呈周期性的变化。表面性质的周期性变化主要源于氮气射流等离子体的物理刻蚀作用。     

打磨对木粉/聚乙烯复合材料射流等离子体表面处理时效性的影响

采用空气气氛的射流等离子体对木粉/聚乙烯复合材料进行表面处理,以改善胶接性能。利用接触角和胶接强度测试以及红外光谱和X-射线光电子能谱分析等方法,研究了表面打磨对复合材料等离子体表面处理时效性的影响。研究结果表明,直接等离子体处理以及打磨后再等离子体处理都可以明显提高复合材料的胶接强度,相比之下,打磨后再等离子体处理可以在复合材料表面形成更多的含氧极性基团,有利于胶接性能的改善。木粉/聚乙烯复合材料的等离子体表面处理存在一定的时效性,与直接等离子体处理的复合材料相比,随着处理试样放置时间的延长,先打磨再等离子体处理的复合材料表面接触角、含氧极性基团以及胶接强度的变化幅度更小,表现出更小的处理时效性。尽管存在处理时效性,但等离子体处理后的胶接强度仍远好于未处理的试样。     

等离子体放电气氛对WPC协同表面处理效果的影响

采用打磨、偶联剂涂覆与射流等离子体放电的协同处理方法对聚乙烯木塑复合材料(PE-WPC)进行表面处理,以改善其胶接性能。利用胶接强度测试、接触角测试、红外光谱分析和X-射线光电子能谱分析等方法研究了氮气、氧气、空气三种等离子体放电气氛对WPC协同表面处理效果的影响。结果表明:不同等离子体放电气氛的协同处理,都能在材料表面引入大量含氮、含氧和含硅的极性基团,改善其胶接性能。不同的等离子体放电气氛对材料表面协同处理效果的影响不同,氧气气氛对材料表面的氧化刻蚀作用较为明显,能引入更多的硅氧官能团;而氮气气氛对材料表面的化学改性较为突出,在材料表面引入更多的含氮和含氧基团,改善材料表面的润湿性能和胶接性能。实际胶接时可以针对不同的处理气氛匹配不同的胶黏剂以获得更好的胶接性能。     

木粉含量对木粉/PE复合材料胶接性能的影响

研究了木粉含量对木粉/PE(聚乙烯)复合材料表面性能的影响,并探讨了木粉含量对AEA(双组分丙烯酸酯胶粘剂)和EVA(乙烯-醋酸乙烯酯)-HMA(热熔胶)胶接的木粉/PE复合材料之胶接性能的影响。研究结果表明:随着木粉含量的增加,打磨的木塑复合材料表面含氧基团增多,而未打磨的表面基本没有含氧基团;AEA胶接打磨木塑复合材料的胶接强度随木粉含量增加而增大,而木粉含量对EVA-HMA胶接木塑复合材料的影响无规律性且较小;此外,试件表面水的接触角受试件表面粗糙复杂程度的影响大于材料表面亲/疏水性所产生的影响。     

贮存环境对PE-WPC等离子体处理时效性的影响(I)——表面结构及粘接性能

利用等离子体处理技术对聚乙烯木塑复合材料(PE-WPC)进行表面处理以改善其胶接性能,将处理后的WPC分别贮存在真空(室温)、空气(室温)和空气(低温)环境中,利用接触角、FT-IR和胶接强度测试等手段,研究了不同贮存环境对等离子体处理后材料表面时效性的影响。接触角测试结果表明,随着放置时间的延长,贮存在3种环境中的试样的表面接触角均逐渐增大,相比之下,处于真空和低温环境中的试样接触角变化较小;红外光谱分析表明,贮存于3种环境中的试样表面的-OH基团随着放置时间的延长几乎消失,-C-O和C=O基团也逐渐减少,处于真空和低温环境中的试样表面残留的极性基团较空气中的试样多。胶接强度测试结果表明,随着放置时间的延长,放置在3种环境中的试样表面粘接强度逐渐降低,其中放置于空气(室温)中的试样的粘接强度降低的幅度最大。等离子体处理尽管存在时效性,但贮存30d的试样的胶接性能仍优于未处理的试样。     

贮存环境对PE-WPC等离子体处理时效性的影响(Ⅱ)——表面元素分析

利用等离子体处理技术对PE-WPC进行表面处理以改善其胶接性能,将处理后的木塑复合材料分别贮存在真空(室温)、空气(室温)和空气(低温)环境中,利用XPS分析手段,研究了等离子体处理PE-WPC表面元素的变化,以此表征贮存环境对等离子体处理表面时效性的影响。结果表明,随着放置时间的延长,贮存于真空、空气(室温)和低温环境中的等离子体处理PE-WPC表面的C元素相对含量均增加,O元素则相反,O/C值降低。与空气(室温)环境相比,真空和低温环境下等离子体处理PE-WPC表面O/C值降低的幅度减缓。     

Potassium methyl siliconate‐treated pulp fibers and their effects on wood plastic composites: Water sorption and dimensional stability

Potassium methyl siliconate (PMS) was investigated as a new nano modifier of wood fiber and wood flour to improve the compatibility between the fiber/flour and the plastic matrix in fiber reinforced plastic composites. Before injection molding, bleached and brown pulp fibers and mixed species wood flour were pretreated in PMS solutions. The morphology of the treated and untreated fiber and flour, the compatibility of PMS‐treated fiber and flour with polyethylene (PE), and the water sorption and volumetric swell of PMS‐treated fiber/flour plastic composites in a long‐term soaking test were evaluated. Fiber and flour treated with PMS increased the compatibility between the fiber/flour and the PE matrix. The increased compatibility of PMS‐treated fiber and flour with the matrix contributed to the reduction of water sorption and, thus, increased dimensional stability. For all composites, water sorption and volumetric swell of fiber/four plastic composites decreased as the ratio of fiber to flour increased. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Terminally functionalized polyethylenes as compatibilizers for wood–polyethylene composites

Isocyanate‐terminated polyethylenes (PE), PE‐MDI and PE‐PMDI, were synthesized by reacting polyethylene monoalcohol (PEA) with 4,4′‐methylenediphenyl diisocyanate (MDI) and polymeric methylene diphenyl diisocyanate (PMDI), respectively. Effects of PEA, PE–MDI, and PE–PMDI on the mechanical properties and water resistance of wood–PE composites were investigated. All three compatibilizers increased the strength of the wood–PE composites. Composites containing PE–MDI or PE–PMDI exhibited a higher modulus of rupture (MOR) than those with PEA. The addition of PE–MDI and PE–PMDI decreased the water uptake rate of the composites while PEA increased this rate. The superior compatibilization effects of PE–MDI and PE–PMDI were attributed to the formation of covalent bonding between isocyanate and wood. This covalent bonding was demonstrated by the FTIR spectra of the wood residues after a p‐xylene extraction. Scanning electron microscope (SEM) images revealed that isocyanate‐terminated PE samples improved the interfacial adhesion between wood and PE. POLYM. ENG. SCI., 46:108–113, 2006. © 2005 Society of Plastics Engineers     

Comparative study on the effect of manchurian ash and larch wood flour on mechanical property,morphology, and rheology of HDPE/wood flour composites

Effects of wood flour species and polyethylene grafted with maleic anhydride (MA‐PE) on mechanical properties and morphology and torque rheology of high density polyethylene (HDPE)/wood flour composites have been comparatively investigated. The results demonstrated that without compatbilizer, wood flour species exhibited little influence on mechanical properties. In the presence of MA‐PE, the mechanical properties were obviously increased. On the basis of the mechanical property data obtained from wood flour extracted by different methods, the extractant was an important factor affecting the mechanical properties. Manchurian ash and larch wood flours extracted by hot water presented almost the same mechanical properties, and larch wood flour was the most beneficial to enhance the mechanical properties. The scanning electron microscopy (SEM) and the atomic force microscopy (AFM) further confirmed that interfacial adhesion and dispersion of manchurian ash wood flour in composites were effectively improved by MA‐PE. The torque results demonstrated that the chemical reactions of maleic anhydride groups on MA‐PE with hydroxyl on cellulose in wood flour probably took place due to the increase of the equilibrium torque and the appearance of the torque peak, and larch wood flour was more beneficial to prepare the composites containing the higher wood flour content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dimensional stability of wood–polymer composites

Wood–polymer composites (WPC) were prepared by impregnation of polymeric monomers in wood and in situ polymerization. Three polymeric chemicals were chosen for this study: methyl methacrylate (MMA), hydroxyethylene methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA). The effects of polymeric monomers and their combinations on moisture adsorption (M), anti–moisture adsorption efficiency (AME), liquid water uptake (D), water repellency efficiency (WRE), longitudinal, radial, tangential, and volumetric swelling properties (S) after soaking, and antiswelling efficiency (ASE) were investigated. It was found that M was different for different methacrylate combinations and depended not only on the composition of the impregnants, but also on wood properties. Liquid water uptake was similar regardless of the formulation of the WPC. Wood–polymer composites with high MMA content displayed enhanced dimensional stabilities, but WPCs with high HEMA content did not. Tangential and volumetric ASEs were strongly dependent on the type of treatment. Mold growth tests showed that wood treated with HEMA alone had no surface mold growth, and wood treated with MMA alone also showed less mold growth than did the control samples. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 5085–5094, 2006     

处理剂对木塑产品性能的影响

研究了不同表面处理剂处理木粉对木塑复合材料流变性能和力学性能的影响。结果表明，硬脂酸、白油、钛酸酯偶联剂和超分散剂都能改善木粉与聚乙烯（PE）树脂的相容性，提高木塑材料的加工性能，用超分散剂处理的木塑材料的加工性能最好，钛酸酯偶联剂次之，硬脂酸加白油最差；钛酸酯偶联剂、超分散剂处理的木塑材料的物理力学性能比硬脂酸加白油处理的略好，只有冲击强度略有降低。     

Improvement of Mechanical Properties of Jute Fibers-Polyethylene/Polypropylene Composites: Effect of Green Dye and UV Radiation

Jute-reinforced polyethylene (PE), polypropylene (PP) and mixture of PP/PE composites were prepared. It was found that 90% PP and 10% PE matrices based jute reinforced composites performed the better results. UV radiation at different intensities was applied both on matrices and jute. Mechanical properties of the irradiated jute- and matrices-based composites were found to increase significantly. Optimized jute fabrics were also treated with different concentrations of green dye (0.1–1%, w/w) with 2% K₂O₈S₂ in methanol solution for 2–8 min. A composite made of 0.5% green dye jute (5 min soaking time) and irradiated matrix showed the best mechanical properties.