表面改性对PVC/稻糠发泡复合材料的影响

研究了纳米CaCO3、硅烷偶联剂、甲基丙烯酸甲酯(MMA)改性稻糠对PVC/稻糠发泡复合材料性能的影响.结果表明:纳米CaCO3能改善稻糠的耐热性,用硅烷偶联剂处理稻糠的发泡复合材料冲击性能好于用MMA微波处理稻糠发泡复合材料;而用MMA微波处理稻糠的发泡复合材料在拉伸性能、弯弹性模量及加工性能优于硅烷偶联剂处理的稻糠发泡复合材料.     

Glass fiber reinforced ROMP-based bio-renewable polymers: Enhancement of the interface with silane coupling agents

In this study, the influence of silane coupling agents on interfacial adhesion in glass fiber reinforced polymers from the ring-opening metathesis polymerization (ROMP) of a linseed oil-based monomer and dicyclopentadiene is investigated experimentally. Two types of silane coupling agents, norbornenylethyldimethylchlorosilane (MCS) and norbornenylethyltrichlorosilane (TCS), are examined. Interfacial shear strength (IFSS) is evaluated by the microbond technique. The IFSS increases by about 150% for the MCS-treated fibers and by about 50% for the TCS-treated fibers compared to untreated fibers. Dynamic mechanical analysis of composite panels made with untreated and silane-treated fibers reveals that MCS-treated fiber composites have the highest storage modulus and glass transition temperature, indicating strong interfacial interactions at the glass/matrix interface. Short beam shear tests and scanning electron microscopy of fracture surfaces also confirm that MCS is more effective than TCS at improving interfacial adhesion.     

Wood flour as a low-cost reinforcing filler for polyethylene: studies on mechanical properties

Wood flour was used as a reinforcing filler for high-density polyethylene (HDPE). Different fibre treatments were carried out to improve the bonding at the polymer-fibre interface. Wood flour composites coated with alkoxy-silane coupling agents (silane A-172 and A-174) generally showed higher tensile strength and modulus values. A significant improvement in tensile properties was achieved with the addition of polymethylenepolyphenyl isocyanate. The Izod impact strength of the composites decreased with an increase in filler concentration.     

Novel lignocellulosic hybrid particleboard composites made from rice straws and coir fibers

Novel lignocellulosic hybrid particleboard composites with low cost and high performance using the mixture of rice straws and coir fibers were developed in this work. NaOH (sodium hydroxide) aqueous solution was used to remove the wax and silica layer of rice straw surface. The effects of rice straws/coir fibers (R/C) mass ratios on the physical (thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties of particleboard composites were investigated. The results show that NaOH treatment was an effective method for improving wettability of rice straw surface with smaller contact angles and larger diffusivity–permeability constant. The SEM (scanning electron microscope) observation also gave some evidences such as more rough surface and less number of silica cells after NaOH treatment for improving wettability of rice straw surface. The coir fibers content had a significant negative linear effect on the bending properties and thickness swelling, but a significant positive linear effect on the internal bonding strength due to the lower wax and holocellulose content of coir fiber. When no diisocyanate resin applied, the particleboard composites made with only phenol formaldehyde resin at the optimal R/C ratio satisfied the requirements for load-bearing boards used in dry conditions based on Chinese Standard, indicated that the mixture of rice straws and coir fibers to make high quality particleboard composites was a cost-effective and environment friendly approach.     

硅烷偶联剂对电子束固化碳纤维复合材料的增效研究

根据碳纤维表面的特点及其复合材料中树脂基体进行电子束固化的机理,对碳纤维表面进行预氧化以提高碳纤维表面含氧官能团的含量,利用偶联剂的化学架桥作用对电子束固化复合材料界面进行了增效研究。采用X射线光电子能谱（XPS）对处理后碳纤维表面化学成分进行了分析,并采用层间剪切强度对电子束固化复合材料界面粘合性能进行了评价。结果表明,碳纤维表面的含氮官能团使电子束固化复合材料中碳纤维与环氧树脂基体之间的粘合强度减弱,偶联剂与预氧化碳纤维表面进行了强相互作用,使电子束固化复合材料层间剪切强度得到提高。     

Effects of fiber surface treatments on mechanical properties of epoxy composites reinforced with glass fabric

In this study, effects of fiber surface treatments on mechanical behavior and fracture mechanism of glass fiber/epoxy composites were investigated experimentally. To change the composition of the glass and regenerate to the hydroxyl groups, activation pretreatment of heat cleaned woven glass fabric was performed using (v/v) HCl aqueous solution at different concentrations before silane treatment. The treatment of silanization of heat cleaned and acid activated glass fibers with γ-glycidoxypropyltrimethoxysilane were performed. In this work, short beam shear test has been conducted to determine the performance of the acid treatment and the silane treatment in terms of the interlaminar shear strength. The silane coating on the heat cleaned glass fibers increased the interlaminar shear strength of the composite. However, the silane coating on the acid activated glass fibers did not improve the interlaminar shear strength of the composite. In addition, the strengths of the glass fabric specimens in tension and flexure were investigated. When the glass fibers are first treated with HCl solution and then with silane coupling agent, the tensile strengths of the composites decreased significantly. Scanning electron photomicrographs of fractured surfaces of composites were performed to explain the failure mechanisms in the composite laminates broken in tension.     

Using silane-functionalized graphene oxides for enhancing the interfacial bonding strength of carbon/epoxy composites

Silane-functionalized graphene oxides (sGOs) were fabricated with four different self-assembled monolayers (SAMs) to reinforce an epoxy adhesive, with the aim of improving the bonding strength of carbon/epoxy composites. The oxygen-containing groups on the surface of graphene oxide (GO) were converted by the SAMs to amine, epoxy, or alkyl groups. The successful reaction between the silane molecules of the SAMs and functional groups of GO was evidenced by the results of different characterization methods such as Fourier transform infrared spectroscopy. It was found that the average thickness of the sGO flakes was higher than that of GO flakes. The bonding strength of a carbon fiber/epoxy composite, tested with a single lap joint bonded with an epoxy adhesive, was increased by 53% after the addition of a sGO that contained amine groups. These results show that sGOs, especially those containing amine functional groups, can strengthen the interfacial bonding between the carbon fibers and epoxy adhesive.     

The influence of electron beam irradiation on the shear bond strength of glass-reinforced frameworks and veneer composites

The bond between glass fibre framework and veneer composite can be achieved by silane coupling agents or by monomers that penetrate into a polymer network. However, it has been clinically demonstrated that his bond can fail. This study investigated whether electron beam irradiation improved the bond strength of fibre-frameworks and veneer composite with and without additional coupling agents.     

甘蔗渣显微结构对聚乳酸/甘蔗渣复合材料结构与性能的影响

采用碱处理、硅烷偶联剂处理以及碱处理配合硅烷偶联剂处理等方式改性甘蔗渣(BF),采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、热重分析(TGA)以及力学性能测试等研究改性后BF结构的变化。结果表明,不同改性方法均明显改变了BF的结构及改性剂的键合方式。碱处理能够去除BF中的半纤维素等小分子聚合物以及部分非晶区的纤维素,导致BF热稳定性降低,结晶度上升。碱液浓度偏高以及碱处理时间过长会导致BF的纤维表面原纤化,虽然能增加与偶联剂反应的面积,但BF的强度大大下降,不利于BF的增强作用。因此,硅烷偶联剂处理的BF/PLA复合材料的相容性及力学性能最佳,其次为碱处理配合硅烷偶联剂处理的BF/PLA复合材料,最后为碱处理的BF/PLA复合材料。     

Synergistic effect of coupling agents and fiber treatments on mechanical properties and moisture absorption of polypropylene–rice husk composites and their foam

Rice husks and polypropylene were applied as the fibers and matrix, respectively, to make composites. Polypropylene-grafted maleic anhydride (PP-g-MA) and styrene ethylene butadiene styrene-grafted maleic anhydride (SEBS-g-MA) were used as coupling agents. The rice husks were also treated with NaOH, silane, or NaOH + HCl + silane to enhance the effect of the coupling agents. Using a combination of 2 wt% PP-g-MA and 1 wt% SEBS-g-MA, the impact strength of the composite increased, but the tensile strength and modulus were not reduced relative to the use of PP-g-MA alone. The three treatments – NaOH, silane and NaOH + HCl + silane – and added coupling agents improved the impact strength and decreased the moisture absorption rate of the composites except for those subjected to the alkaline treatments. The foaming results showed that adding coupling agents improved the cell structure and reduced the density of the foam.     

HAC/PVA基MDF材料中偶联剂作用机理研究

研究了在HAC/PVA基MDF复合材料中掺入硅烷偶联剂对其抗折性能和耐水性的影响,并用XPS方法研究了γ-甲基丙烯酰氧基丙基三甲氧基硅烷(A-174TM)与铝酸一钙(CaAl₂O₄)之间所进行的化学反应,据此探讨硅烷偶联剂在MDF复合材料中的增强与改善耐水性的机理。     

Substantiating the role of phase bicontinuity and interfacial bonding in epoxy-silica nanocomposites

Nanocomposites consisting of an epoxy network matrix and a silica reinforcing phase were produced from a resin mixture functionalized with alkoxysilane coupling agents. Particulate nanocomposites were obtained by dispersing silica-organosol particles in the resin, while bicontinuous phase nanocomposirtes were obtained by the in-situ hydrolysis and condensation of tetraethoxysilane containing minor amounts of γ-glycidoxyl trimethoxysilane. Functionalization of the epoxy resin with an amine silane coupling agent was found to be more effective in aiding the dispersion of silica sol particles in the resin than the corresponding resin functionalized with a mercaptan silane coupling agent. Similar differences in the efficiency of coupling agent grafted on to the epoxy resin were observed for bicontinuous phase nanocomposites. The amine silane functionalization produces denser silica domains, which results in a higher rubber-plateau modulus and higher resistance to solvent penetration. The study also showed that the particulate nanocomposites are very ineffective in improving the solvent resistance of the base resin, even when the resin is grafted with a very efficient amine silane coupling agent, which promotes interfacial bonding. The different types of morphology were characterized by transmission electron microscopy and small angle X-ray scattering analysis.     

Preparation and mechanical property of poly(ε-caprolactone)–matrix composites containing nano-apatite fillers modified by silane coupling agents

This study aims to improve the tensile strength and elastic modulus of nano-apatite/poly(ε-caprolactone) composites by silane-modification of the nano-apatite fillers. Three silane coupling agents were used to modify the surfaces of nano-apatite particles and composites of silanized apatite and PCL were prepared by a technique incorporating solvent dispersion, melting-blend and hot-pressing. The results showed that the silane coupling agents successfully modified the surfaces of nano-apatite fillers, and the crystallization temperatures of the silanized apatite/PCL composites were the higher than that of the non-silanized control material, although the melting temperature of the composites remained almost unaffected by silanization. The ultimate tensile strength and elastic modulus of the silanized composites reached 22.60 MPa and 1.76 GPa, as a result of the improved interfacial bonding and uniform dispersion of nano-apatite fillers. This study shows that the processing technique and silanization of nano-apatite particles can effectively improve the tensile strength and elastic modulus of nano-apatite/PCL composites.     

稻壳灰/天然橡胶胶乳复合材料结构与性能研究

采用稀土偶联剂和硅烷偶联剂改性稻壳灰(RHA)填充天然胶乳(NRL)制备稻壳灰/天然橡胶胶乳复合材料,用扫描电镜(SEM)、热重分析仪(TG-DTG)以及力学性能测试等技术研究了稻壳灰在复合材料中的结构、形态分布和热氧稳定性及力学性能。结果表明,采用偶联剂对RHA进行改性处理,能显著改善RHA在橡胶相的分散程度,增强RHA粒子与橡胶基体之间作用力,从而提高RHA/NRL复合材料的力学性能和抗氧老化性能,并且稀土偶联剂RHA/NR复合材料力学性能和抗氧老化性能的改进更加明显。     

几种不同改性剂对稻草/丙烯腈-丁二烯-苯乙烯复合材料性能的影响

以稻草纤维及丙烯腈-丁二烯-苯乙烯（ABS）为原料,分别以活性炭、Al₂O₃、SiO₂和硅烷偶联剂为增强改性剂,通过混炼-模压工艺制备了改性剂-稻草/ABS复合材料,对比研究了几种不同增强改性剂的增强效果及其增强机制。结果表明：硅烷偶联剂对稻草/ABS复合材料的增强效果较差,活性炭、Al₂O₃和SiO₂对稻草/ABS复合材料的增强均优于硅烷偶联剂,其中Al₂O₃的增强效果最佳。当Al₂O₃的添加量（Al₂O₃∶ABS质量比）为5%时,Al₂O₃-稻草/ABS复合材料的拉伸、弯曲及冲击强度分别达到最大值27.719 MPa、61.05 MPa和26.53 kJ/m²;当无机物添加量（无机物∶ABS质量比）为5%时,复合材料的耐水性能表现为：5% Al₂O₃ > 5%活性炭 > 5% SiO₂ > 未添加,与复合材料的力学性能梯度相符;改性剂-稻草/ABS复合材料的流变性能则表现为：5%活性炭 > 5% Al₂O₃ > 5% SiO₂ > 未添加。     

Development of slate fiber reinforced high density polyethylene composites for injection molding

During the last decade the use of fiber reinforced composite materials has consolidated as an attracting alternative to traditional materials due to an excellent balance between mechanical properties and lightweight. One drawback related to the use of inorganic fibers such as those derived from siliceous materials is the relative low compatibility with conventional organic polymer matrices. Surface treatments with coupling agents and the use of copolymers allow increasing fiber–matrix interactions which has a positive effect on overall properties of composites. In this research work we report the use of slate fiber treated with different coupling agents as reinforcement for high density polyethylene from sugarcane. A silane (propyltrimethoxy silane; PTMS) and a graft copolymer (polyethylene-graft-maleic anhydride; PE-g-MA) were used to improve fiber–matrix interactions on HDPE-slate fiber. The effect of the different compatibilizing systems and slate fiber content were evaluated by scanning electron microscopy (SEM), dynamic thermomechanical analysis (DTMA) as well as mechanical properties (tensile, flexural and impact). The results show that the use of silane coupling agents leads to higher fiber–matrix interactions which has a positive effect on overall mechanical properties. Interesting results are obtained for composites containing 30 wt.% slate fiber previously treated with propyltrimethoxy silane (PTMS) with an increase in tensile and flexural strength of about 16% and 18% respectively.     

Silane coupling agents used for natural fiber/polymer composites: A review

Natural fiber reinforced polymer composites (NFPCs) provide the customers with more alternatives in the material market due to their unique advantages. Poor fiber–matrix interfacial adhesion may, however, negatively affect the physical and mechanical properties of the resulting composites due to the surface incompatibility between hydrophilic natural fibers and non-polar polymers (thermoplastics and thermosets). A variety of silanes (mostly trialkoxysilanes) have been applied as coupling agents in the NFPCs to promote interfacial adhesion and improve the properties of composites. This paper reviews the recent progress in using silane coupling agents for NFPCs, summarizes the effective silane structures from the silane family, clarifies the interaction mechanisms between natural fibers and polymer matrices, and presents the effects of silane treatments on the mechanical and outdoor performance of the resulting composites.     

Electron-beam-irradiated rice husk powder as reinforcing filler in natural rubber/high-density polyethylene (NR/HDPE) composites

The use of rice husk (RH) powder as a reinforcing filler in blends of natural rubber and high-density polyethylene (NR/HDPE) was studied via surface modification of the particle surface. The RH powder was pre-washed with sodium hydroxide (NaOH) prior to coating with liquid natural rubber (LNR) and reinforced by electron beam (EB) irradiation. The effects of the radiation dosage on the LNR-coated rice husk (RHr) as a reinforcing agent in the composite were evaluated from the mechanical and thermal properties, as well as from the blend homogeneity. The mechanical properties enhanced with the dosage of radiation on the RHr, and reached an optimum dose in the range 20–30 kGy. The composites filled with radiated RHr showed the highest storage modulus (E′) and low tangent delta (tan δ) a radiation dosage of 30 kGy. The scanning electron microscopy (SEM) micrograph of the fractural tensile surface showed that an effective RHr particle matrix interaction occurred in the RH powder at a radiation dosage of 20 kGy. Improved RH filler–matrix interfacial bond strength and adhesion to the matrix were achieved by coating the RH powder and curing the rubber coat by electron beam irradiation.     

Electron-beam-irradiated rice husk powder as reinforcing filler in natural rubber/high-density polyethylene (NR/HDPE) composites

The use of rice husk (RH) powder as a reinforcing filler in blends of natural rubber and high-density polyethylene (NR/HDPE) was studied via surface modification of the particle surface. The RH powder was pre-washed with sodium hydroxide (NaOH) prior to coating with liquid natural rubber (LNR) and reinforced by electron beam (EB) irradiation. The effects of the radiation dosage on the LNR-coated rice husk (RHr) as a reinforcing agent in the composite were evaluated from the mechanical and thermal properties, as well as from the blend homogeneity. The mechanical properties enhanced with the dosage of radiation on the RHr, and reached an optimum dose in the range 20–30 kGy. The composites filled with radiated RHr showed the highest storage modulus (E′) and low tangent delta (tan δ) a radiation dosage of 30 kGy. The scanning electron microscopy (SEM) micrograph of the fractural tensile surface showed that an effective RHr particle matrix interaction occurred in the RH powder at a radiation dosage of 20 kGy. Improved RH filler–matrix interfacial bond strength and adhesion to the matrix were achieved by coating the RH powder and curing the rubber coat by electron beam irradiation.     

偶联剂对硼酸铝晶须/双马来酰亚胺性能的影响

应用自行合成的一类新型硼酸酯偶联剂及硅烷偶联剂等对硼酸铝晶须进行表面处理,考察了硼酸铝晶须对双马来酰亚胺树脂体系性能的影响.结果表明,硼酸酯处理后的晶须对材料的改性作用较硅烷更加显著;硼酸铝晶须添加到双马来酰亚胺树脂中后,材料的弯曲强度在晶须含量为5%时达到最大值,而后随晶须含量的增大稍有下降;随晶须添加量的增大材料的弯曲模量和耐热性逐渐提高;经硼酸酯处理的晶须与树脂基体具有更好的界面粘接.