废印刷电路板非金属粉负载二氧化硅杂化填料的制备及其在不饱和聚酯中的应用

为增强废印刷电路板非金属粉(WPCBP)与聚合物基体之间的界面结合作用,采用溶胶-凝胶法在WPCBP表面原位负载了一层纳米二氧化硅粒子(SiO2),制备了一种新型的WPCBP-SiO2杂化填料.SEM、TGA和FTIR证明SiO2通过化学键成功负载到了杂化填料的表面.采用含双键的界面改性剂对杂化填料进行改性后,应用于不饱和聚酯树脂基体,探讨了未改性杂化填料及表面改性杂化填料对不饱和聚酯复合材料的力学性能、界面结合作用和热稳定性能的影响.结果表明,新型的杂化填料WPCBP-SiO2能够与不饱和聚酯基体形成强的界面结合作用,显著提高不饱和聚酯复合材料的力学性能和热稳定性能,且表面改性后复合材料的各项性能得到进一步提高.     

废印刷电路板非金属粉与埃洛石纳米管对不饱和聚酯热稳定性和阻燃性能的影响

为减轻废印刷电路板非金属粉(WPCBP)在回收过程中对环境的污染和资源的浪费,实现WPCBP在聚合物基体中的高值化利用,将粉碎干燥后的WPCBP与埃洛石纳米管(HNTs)添加到不饱和聚酯树脂(UPE)基体中,制备了一种新型环保的WPCBP-HNTs/UPE复合材料。利用SEM和TEM对两种填料的结构形貌及其在复合材料中的分散状况和界面结合进行了表征,采用热失重分析仪、锥形量热仪、极限氧指数仪等对WPCBP-HNTs/UPE复合材料的热稳定性和阻燃性能进行了系统的研究。结果表明,WPCBP和HNTs能够显著提高复合材料的热分解稳定性和阻燃性能。通过SEM和EDS对复合材料燃烧后的碳渣进行了分析,并探讨了阻燃机制,分析了WPCBP和HNTs对WPCBP-HNTs/UPE复合材料的力学性能和热变形性能的影响。     

SiO2的功能化改性及其与聚合物基体的界面研究进展

纳米二氧化硅(SiO_2)作为一种最常用的无机纳米材料,受到了各个领域研究者的广泛关注且已得到实际应用。以纳米SiO_2作为改性填料,得到的聚合物纳米复合材料兼具了聚合物基体和纳米SiO_2二者的优点,因而表现出优异的力学性能、热学性能、光学性能以及化学稳定性等。但是纳米SiO_2表面富含大量活性硅羟基,极易团聚,用一般方法难以实现其在纳米尺度上的均匀分散以及与高分子基体材料间良好的界面粘结。因此,在制备纳米SiO_2改性的聚合物基纳米复合材料前,研究者们常通过对SiO_2进行表面改性,以改善其与聚合物基体的界面相容性及其在聚合物基体中的分散性,并赋予其一定的功能性。目前,纳米SiO_2的改性方法有很多,总的来说主要为物理改性和化学改性,而根据改性剂的种类不同,又可以分为有机改性、无机改性和杂化改性三种。聚合物/纳米SiO_2复合材料的优异性能不仅取决于有机聚合物和无机纳米SiO_2两组分的性能,还取决于两者间的界面结构和形态特征。尽管界面相的体积含量只占总体积含量中很少的一部分,但是界面间的相互作用、界面处聚合物结构与基体结构的差异、界面相微观形貌的变化等都会使整个复合体系的宏观性能发生明显的改变。因而针对有机聚合物与无机纳米SiO_2间的界面研究对于纳米复合材料性能的优化设计具有重要的科学意义。近年来,关于聚合物与无机纳米粒子之间的界面研究主要集中在两个方面:一方面是聚合物及无机纳米粒子表面的物理、化学性质对界面处性能的影响;另一方面是聚合物基体与无机纳米粒子之间的界面相互作用对复合材料性能的影响。目前,常通过现代仪器分析技术测试界面相的微观形貌(如粗糙程度、厚度等)及化学结构(如化学键合方式、键能等),或结合分子动力学模拟阐明分子集合体结构以及相互间的微观作用机理,从理论角度更准确地解释界面性能和界面行为,为复合材料的优化设计提供理论基础和新方法。本文归纳了有机改性、无机改性和杂化改性三种方法在纳米SiO_2的功能化方面的研究进展,讨论并对比了不同改性方法的优势和缺点,较全面地综述了当前现代仪器分析表征和分子动力学模拟在聚合物/SiO_2界面作用研究方面的最新进展,最后展望了纳米SiO_2与聚合物基体界面作用未来研究的工作重点。     

PA6/SiO_2纳米复合材料的制备及性能研究

以可反应性纳米SiO_2为填料,通过原位聚合法制备了聚酰胺6(PA6)/SiO_2纳米复合材料。利用透射电子显微镜(TEM)、热重分析仪(TG)、红外光谱分析仪(FT-IR)、差热扫描量热仪(DSC)和X-射线衍射仪研究了纳米SiO_2的分散行为、界面强度、热稳定性能和结晶熔融行为等。设定纳米SiO_2的加入时间,探讨纳米SiO_2与PA6基体间的界面结构对复合材料性能的影响。结果显示,纳米SiO_2表面的反应性氨基能够与PA6分子链作用,形成强的界面效应;纳米SiO_2的异相成核作用,提高了PA6的结晶度;显著提高了PA6的力学性能;对基体材料的结晶熔融行为的影响较小。     

共混型石墨烯-nanoSiO_2/TPU复合材料的制备与性能

采用熔融共混技术制备了氧化石墨烯(GO)-nano SiO_2杂化材料填充改性的形状记忆热塑性聚氨酯(GO-nano SiO_2/TPU)复合材料,探讨了GO-nano SiO_2杂化材料对复合材料力学性能、熔融指数及形状记忆性能的影响。结果表明:GO-nano SiO_2含量对GO-nano SiO_2/TPU复合材料的力学性能有明显的影响,其含量为0.5wt%~1wt%时,GO-nano SiO_2/TPU复合材料的综合力学性能较好。熔融指数分析表明,填料的加入会降低材料的加工流动性能。形状记忆性能研究表明,加入GO-nano SiO_2杂化材料使得GO-nano SiO_2/TPU复合材料的形状固定率先降低后上升,在含量为1wt%后上升趋势更加明显;而形状回复率随填料含量的增加而呈降低趋势,并且在100℃高温这种变化趋势更加明显和稳定,回复温度越高,形状回复率越好。     

不饱和聚酯纳米复合材料研究进展

纳米粒子改性不饱和聚酯不但能实现同时增强增韧,提高树脂综合力学性能,而且能改善树脂的热学、耐水和耐化学腐蚀等性能。综述了当前纳米蒙脱土、SiO2、TiO2等纳米不饱和聚酯复合材料研究进展情况,详细探讨了纳米用量、粒子尺寸、表面形态、表面改性处理、相界面等因素对复合材料性能的影响及纳米粒子增韧增强的机理。     

纳米SiO_2/石墨烯-阻燃环氧树脂复合材料的制备及性能研究

以环氧树脂(EP)作为基体材料,采用溶胶-凝胶法和表面改性工艺制备了基于氧化石墨烯和纳米SiO_2组成的新型石墨烯基杂化材料(r-SGO),并进一步制备了纳米SiO_2/石墨烯-阻燃环氧树脂复合材料(r-SGOn/EP)。利用FT-IR光谱、Raman光谱和SEM等手段,分析了复合材料的化学结构、微观形貌和界面结合性能,研究了不同含量的r-SGO对复合材料的机械性能、热稳定性和阻燃性能的影响。结果表明,大量的SiO_2通过共价键成功地吸附在GO表面;r-SGO能够均匀地分散在环氧树脂基体中,环氧树脂与纳米材料界面间有很强的相互作用,引入的r-SGO增加了环氧树脂网络的交联密度,提高了复合材料的热稳定性;随着r-SGO含量的增加,r-SGOn/EP复合材料的综合性能提高。r-SGO1.5/EP复合材料的玻璃化转变温度为199℃,抗拉强度为71 MPa,导热系数为0.29 W/(m·K),初始降解温度为345℃,最大降解温度为453℃。r-SGO1.5/EP的最大质量损失率低于r-SGO0.5/EP,热稳定提高。r-SGO1.5/EP复合材料的最大极限氧指数(LOI)值为30.5%,r-SGOn/EP复合材料通过燃烧过程可以转变为具有较高热氧化稳定性和高径厚比的SiO_2纳米片,其片层具有良好的吸附性和阻隔功能,能够有效地发挥层状结构的阻燃作用。     

木塑复合材料的界面改性方法

表面有机化改性是提高木质填料(木纤维或木粉)的分散程度和增强其与聚合物基体界面相互作用的重要手段。对于木塑复合材料而言,木质填料与树脂基体的界面粘接程度是有效传递载荷、提高力学性能、降低吸水率和提高尺寸稳定性的关键因素。针对国内外木塑复合材料的研发现状,本文主要概述了木质填料的表面处理方法及其对木塑复合材料性能的影响。     

不饱和聚酯复合材料的改性研究

综述了不饱和聚酯复合材料改性方面的最新发展．介绍了不饱和聚酯复合材料在表面、界面、低收缩改性以及天然纤维和无机物增强方面的研究,并着重介绍了不饱和聚酯／层状硅酸盐蚋米复合材料的制备和性能．     

有机累托石/不饱和聚酯/玻璃纤维三元复合材料的研究

采用有机累托石(OREC)改性不饱和聚酯(UP)，以改性的UP为基体，以玻璃布为增强材料制备了有机累托石／不饱和聚酯／玻璃纤维三元复合材料(OREC／UP／FIBERS)。通过X射线衍射(XRD)分析了三元复合材料的微观结构，测试了该三元复合材料的力学性能，利用扫描电镜(SEM)、透射电镜(TEM)初步分析了复合材料的增强机理，并研究了三元复合材料的耐湿热性及耐介质性能。结果表明，当OREC添加量为树脂质量分数的2％时，复合材料的综合力学性能较好，且OREC／UP／FIBERS三元体系的耐湿热性及耐碱性较不饱和聚酯／玻璃纤维复合材料的好。     

The filler–rubber interface and reinforcement in styrene butadiene rubber composites with graphene/silica hybrids: A quantitative correlation with the constrained region

Silica/reduced graphene oxide (SiO₂@rGO) hybrids were fabricated by an electrostatic assembly, and subsequently, SiO₂@rGO was incorporated into styrene butadiene rubber (SBR) to fabricate SBR composites. The dispersion status of SiO₂@rGO and the filler–rubber interfacial interaction were investigated. Likewise, the amount of constrained region was quantified and the findings suggested that the greater the volume fraction of constrained region has possessed, the stronger the interfacial interaction has had. Moreover, the contribution of constrained region to the performance of composites was quantitatively analyzed by the mechanical analysis and the tube model, and the results showed that it is the effect of constrained region, rather than the contents of SiO₂@rGO, which controls the reinforcement of composites. Specifically, the higher the volume fraction of constrained region is, the better the mechanical properties of composites will be. Also, SiO₂@rGO can be utilized as novel reinforcing filler for fabricating the green tire materials with high performance.     

Swelling properties and bioactivity of silica gel/pHEMA nanocomposites

A novel hydrogel based on 2-hydroxyethyl- methacrilate and SiO₂ nanoparticles was prepared. The filler was added at a concentration of 30% w/w of silica nanoparticles to the mass of polymer. The composite material was characterised as far as concerns swelling behaviour in comparison to pHEMA. Swelling ratio of modified pHEMA was higher. Bioactivity of both SiO₂ nanoparticles and the modified hydrogel was evaluated by soaking samples into a simulated body fluid (SBF). FT-IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive system (EDS) results suggest silica nanoparticles keep bioactive in the polymer. SiO₂ filler in a p(HEMA) matrix makes the composite bioactive. Therefore, these composites can be used to make bioactive scaffold for bone engineering.     

Polypropylene/SiO<Subscript>2</Subscript> nanocomposites filled with different nanosilicas: thermal and mechanical properties,morphology and interphase characterization

Untreated and surface-treated SiO₂ nanoparticles with different alkyl chain length (described as C0, 3C1, C8 and C16 according to the number of carbon atoms) on particle surface were used as fillers for isotactic polypropylene (iPP). The iPP/SiO₂ composites containing 2.3 vol% of nanoparticles were prepared by melt blending and injection moulding. The dispersion quality of nanoparticles in matrix was examined using scanning electron microscopy (SEM). The crystallization behaviour of iPP was examined using differential scanning calorimetry (DSC). The mechanical properties of all samples were characterized by tensile test, compact tension (CT) test and dynamic mechanical thermal analysis (DMTA). The particle–matrix interphase behaviour was also examined and discussed. SEM images show that different silicas show different dispersion quality in matrix due to different hydrophobicity. The crystallinity and spherulite size of matrix are overall decreased in composites. The tensile properties of iPP/SiO₂ composites show clear relationship with alkyl chain length on particle surface, i.e. increasing alkyl chain length leads to decreased tensile modulus but increased tensile yield strength and strain, indicating increased interfacial interactions with increased alkyl chain length. The 3C1-composite shows the highest fracture toughness with an improvement by 9% compared to neat iPP, whereas the other composites show decreased values of fracture toughness.     

Tribological properties of surface modified nano-alumina/epoxy composites

Nano-sized Al₂O₃ particles grafted with polystyrene or polyarcrylamide were employed as fillers for fabricating epoxy based composites. Curing habit, mechanical properties and tribological performance revealed by sliding wear tests of the composites were investigated. The experimental results indicated that the nanoparticles accelerate curing of epoxy, increase composites' impact strength and decrease wear rate and frictional coefficient of the composites. The surface modification by means of grafting polymerization can further enhance the properties improvement of epoxy due to the increased filler/matrix interfacial interaction. Compared to frictional coefficient, wear rate of epoxy can be decreased more remarkably by the addition of nano-alumina when rubbing against steel. The wear mode changes from severe peeling off of unfilled epoxy to mild micro-ploughing in the case of nano-alumina filled composites.     

The preparation and properties of biodegradable polyesteramide composites reinforced with nano-CaCO3 and nano-SiO2

Composites were fabricated utilizing melt mixing aliphatic polyesteramide (PEA) with ordinary CaCO₃, nano-CaCO₃, and nano-SiO₂. The effect of filler on the matrix was studied by mechanical properties and hydrolysis rate measuring. The ordinary filler as well as the nano-filler had a negative effect on the stability of the polymer melt, and an improved mechanical property was obtained around a critical concentration of the filler where a percolation phenomenon appeared. When the composites underwent hydrolysis, the inert filler played a role as a mechanical obstacle in the matrix and retarded the hydrolysis; on the other hand, the interfacial area between the filler particle and the matrix resin increased with the filler, which would accelerate the hydrolysis. As a result of these two inverse effects, a minimum and a maximum value appeared in the plot of the degradation rate-filler content graph. For the ordinary filler filled polymer, the filler retarded the hydrolysis; in great contrast, the hydrolysis rate of nano-composites showed a maximum value around the critical concentration of the filler, and was much higher than the neat resin.     

Mechanical reinforcement while remaining electrical insulation of glass fibre/polymer composites using core–shell CNT@SiO2 hybrids as fillers

Carbon nanotubes (CNTs) have been widely used as mechanical reinforcement agents of composites. However, their aggregations, weak interfacial interaction with polymer, as well as high electrical conductivity limit their use in some especial applications. In this paper, the silicon oxide (SiO₂)-coated (CNT@SiO₂) core–shell hybrids with different SiO₂ thickness were prepared and employed to reinforce glass fibre-reinforced bismaleimide–triazine (BT) resin (GFRBT) composites. The results indicated the mechanical properties, including tensile strength and Young’s modulus increased with the increase of SiO₂ thickness and CNT@SiO₂ loading. Such enhanced mechanical properties were mainly attributed to the intrinsically nature of CNTs, homogeneous dispersion of the hybrids, as well as improved interfacial interaction. Meanwhile, the composites remained high electrical insulation (9.63 × 10¹² Ω cm) due to the existence of SiO₂ layer on CNT surface. This study will guide the design of functionalized CNTs and the construction of high-performance composites.     

Influence of short bamboo/glass fiber on the thermal, dynamic mechanical and rheological properties of polypropylene hybrid composites

The present article summarizes the development of polypropylene-bamboo/glass fiber reinforced hybrid composites (BGRP) using an intermeshing counter rotating twin screw extruder followed by injection molding. Maleic anhydride grafted polypropylene (MAPP) has been used as a coupling agent to improve the interfacial interaction between the fibers and matrix. The crystallization and melting behavior were investigated employing differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) indicates an increase in thermal stability of the matrix polymer with incorporation of bamboo and glass fibers, confirming the effect of hybridization and efficient fiber matrix interfacial adhesion. The dynamic mechanical analysis (DMA) showed an increase in storage modulus (E′) indicating higher stiffness in case of hybrid composites as compared with untreated composites and virgin matrix. The rheological behavior of the hybrid composites has also been studied using time–temperature superposition (TTS) principle and corresponding viscoelastic master curves have been constructed.     

Al2Mo3O12/polyethylene composites with reduced coefficient of thermal expansion

Recently, polymer composites reinforced with low fractions of thermomiotic nanoceramics have triggered a lot of research. The efforts have been focused on achieving considerable reduction of the coefficient of thermal expansion (CTE) of polymeric materials without deterioration of other physical properties. In this context, polyethylene (PE) composites reinforced with different loads of Al₂Mo₃O₁₂ nanofillers (0.5–4 mass %) were fabricated by micro-compounding. To enhance the interfacial interaction between the two components, chemical functionalization of Al₂Mo₃O₁₂ was performed with vinyltrimethoxysilane (VTMS) prior to micro-compounding. Infrared spectroscopy and thermogravimetry demonstrated the successful grafting of VTMS on the Al₂Mo₃O₁₂ surface. The composites showed strongly decreased CTEs, up to 46 % reduction for loadings of 4 mass % compared with neat PE, suggesting intimate filler–matrix interactions. The variation of CTEs of the composites in terms of the filler fraction was successfully described by Turner’s model allowing calculation of the bulk modulus of monoclinic Al₂Mo₃O₁₂ (13.6 ± 2.6 GPa), in agreement with the value obtained by an ultrasonic method. The thermal stability of the composites was improved, although the addition of functionalized fillers decreased the degree of crystallinity of the PE to a small extent. The Young’s modulus and yield strength of the composites increased from 6.6 to 19.1 % and 4.0–6.0 %, respectively, supporting the existence of strong filler–matrix interactions, contributing to an efficient load transfer. Finite element analysis of thermal stresses indicated absence of plastic deformation of the matrix or fracture of the nanofillers, for a 100 K temperature drop.