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(SiO_2),制备了一种新型的WPCBP-SiO_2杂化填料。SEM、TGA和FTIR证明SiO_2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-SiO_2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。     

PBS/水曲柳木屑木塑复合材料制备和吸水性的研究

采用双螺杆挤出机和注塑机成功制备了由可生物降解丁二酸丁二醇酯(PBS)和水曲柳木屑组成的木塑复合材料。利用扫描电镜研究了木塑复合材料中水曲柳木屑和PBS基体的界面粘附和木屑嵌入情况;利用电子万能试验机、差热分析仪对吸水前后的PBS和木塑复合材料进行抗拉强度、抗弯强度、热力学性能的测试。结果表明,水曲柳木屑和PBS界面相容性良好,显著提高了木塑复合材料力学性能;在木屑含量为30%(质量分数)时,PBS/水曲柳木屑复合材料的抗拉强度和抗弯强度可达74.4和114.4 MPa;木屑含量为30%(质量分数)的PBS/水曲柳木屑复合材料吸水率最高可达4.5%,此时抗拉强度和抗弯强度分别降低32.1%和13.4%,达到50.5和99.0 MPa,这可能是由于水的增塑作用以及木质颗粒和PBS吸水后膨胀系数不一致导致的界面应力造成的。     

木质纤维/PVC复合材料的蠕变和热稳定性

为研究不同木质类纤维/PVC复合材料的蠕变和热稳定性能,分别以桉木粉(EU)、杨木粉(PO)、松木粉(PI)和竹粉(BA)四种木质纤维为填料,聚氯乙烯(PVC)为基体,采用挤出成型法制备木塑复合材料。采用包括综合热分析仪在内的诸多方法,分析其官能团变化,表面微观形貌和热稳定性,并测试了复合材料的力学性能和蠕变性能。研究结果表明:桉木/PVC复合材料具有较好的蠕变抗性,较优的力学性能,其拉伸强度为36.94MPa,比杨木/PVC,松木/PVC、竹/PVC复合材料分别提高了49.38%、28.04%和29.61%,冲击强度和弯曲强度也相应提高;松木/PVC复合材料具有较好的热稳定性。     

竹炭和壳聚糖对聚氯乙烯基木塑复合材料界面性能的影响

以杨木粉为填充材料,聚氯乙烯(PVC)为基体材料,添加竹炭和壳聚糖,采用挤出成型制备竹炭和壳聚糖改性木粉/PVC木塑复合材料,采用SEM观察复合材料表面微观形貌,采用综合热分析仪分析复合材料的热稳定性,采用FTIR分析其官能团变化,测试了木粉/PVC木塑复合材料的力学性能。结果表明:复合添加竹炭和壳聚糖可较好地改善木粉和PVC的界面作用力和界面相容性,提高复合材料的力学性能,其拉伸强度、冲击强度、弯曲强度和弯曲模量分别比未添加增加14.6%、28.8%、11.1%和4.85%,且复合材料的微观界面缺陷较少;竹炭可提高复合材料的热稳定性,复合添加竹炭和壳聚糖可增加复合材料中羟基、氨基和亚甲基的数量,减弱碳氯键的结合强度,从而增强复合材料中木粉和PVC的界面结合力。     

ABS木塑复合材料的制备与研究

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)塑料为基体,木粉和纳米蒙脱土为填料,采用双螺杆挤出造粒后模压成型工艺制备高性能ABS木塑复合材料。研究了木粉、纳米蒙脱土、界面相容剂ABS接枝马来酸酐(ABS-g-MAH)含量等对ABS木塑复合材料力学性能的影响和SEM分析。结果表明:木粉含量为50%(wt,质量分数,下同),纳米MMT含量为10%,ABS-g-MAH含量为2%时,ABS木塑复合材料的力学性能最佳,弯曲强度达到69MPa、弯曲模量达到5900MPa和冲击强度达到17kJ/cm~2。从材料的SEM图观察到,加入木粉、纳米MMT和ABS-g-MAH后材料的界面相容性得到提高,增强了材料的力学性能。     

氮化硼/聚合物导热复合材料界面热阻调控研究进展

随着5G时代的发展，电子器件领域的热管理问题日发严峻。氮化硼（BN）是一类高热导率（TC）、高绝缘的导热填料，广泛应用于热管理领域，包括六方氮化硼（h-BN）、氮化硼纳米片（BNNS）和氮化硼纳米管（BNNT）。然而，BN表面呈化学惰性，其与基体或其他填料间亲和力低、声子谱失配等，导致了填料与基体/填料间存在明显的界面热阻，限制了复合材料TC的提升，难以满足使用要求。因此，如何调控界面热阻、设计BN/聚合物导热复合材料的热传导界面，并提高复合材料的导热能力是当前亟待解决的难题。研究者分别从理论模拟与实验验证两个角度对热流在界面传导的差异及其原因进行探索。在理论研究中，将分子动力学（MD）模拟及有限元模拟（FEA）等方法结合有效介质模型及其优化模型、Foygel模型等能够对界面热阻（ITR）进行深入的理论模拟与分析；其中，影响界面热阻的关键参数包括BN含量、尺寸及晶体状态、BN的分布形貌等。在实验设计中，为了改善填料与基体间界面热阻，首先对BN表面共价键改性或表面包覆，随后结合聚合物种类设计相应的官能团来改善BN与聚合物的界面作用力；其中BN表面的共价键改性对BN本身晶体结构有一定的破坏...     

“CVI+压力PIP”混合工艺制备低成本 C/SiC复合材料

以低成本填料改性有机硅浸渍剂作为先驱体,采用"化学气相渗透法+压力先驱体浸渍裂解法"(CVI+P-PIP)混合工艺制备了低成本C/SiC陶瓷复合材料.研究了浸渍剂裂解机理,探讨了界面涂层对复合材料性能的影响.结果表明,填料改性有机硅浸渍剂裂解产物结构致密、陶瓷产率高;压力可提高填料改性有机硅浸渍剂的致密效率.混合工艺充分利用沉积SiC基体和裂解SiC基体的致密化特点,有效缩短了制备周期.C/SiC/C三层界面不仅可降低纤维/基体之间结合强度界面,提高了复合材料韧性;而且减缓了氧化性气体扩散到碳纤维表面的速度,改善了复合材料的抗氧化性能.复合材料的抗弯强度达到455MPa,断裂韧性达到15.7MPa·m-1/2.在1300℃空气中氧化3h,复合材料失重仅8.5%.     

碳纤维表面处理对C/PLA复合材料界面粘结强度的影响(Ⅱ)

对硝酸表面处理前后碳纤维增强聚乳酸（Ｃ／ＰＬＡ）复合材料的界面状态进行了研究。重点研究了碳纤维的硝酸表面处理对Ｃ／ＰＬＡ复合材料界面粘结强度的影响以及粘结机理。研究表明,硝酸表面处理可使复合材料的界面粘结强度大幅度增加,复合材料的冲击强度、弯曲强度、弯曲模量和剪切强度亦有不同程度的提高。ＸＰＳ研究发现,央纤维与ＰＬＡ基体间有化学反应发生。界面化学反应程度的增加是复合材料界面粘结强度提高的主要原因;此外,碳纤维表面粗糙度的增加也对界面粘结强度的提高有一定的贡献。     

木粉的酯化处理对木塑复合材料性能的影响

采用乙酸酐溶液对桦木粉进行酯化处理后热压制得HDPE/桦木粉木塑复合材料。考察了反应条件对复合材料力学性能的影响,利用傅立叶红外光谱(FTIR)分析酯化处理前后的木纤维表面官能团,借助电子显微镜和计算机显微图像测试软件处理前后的木材的解剖性质,采用扫描电子显微镜(SEM)观察处理前后复合材料的断面形貌,从而得出最佳的处理工艺,并分析酯化反应程度与木塑复合材料力学强度的相关性。结果表明:控制木纤维的酯化反应程度可以有效改善木纤维表面的疏水性,改变纤维形态和微观形貌,从而提高木塑复合材料的界面结合强度;酯化处理木粉后,反应生成的乙酰基部分取代了纤维表面的羟基,降低了木纤维表面极性,而且木纤维的长度和壁厚有所增大;酯化处理后的木纤维表面平整光滑,且复合材料更加致密。     

Effects of chemical treatments of hybrid fillers on the physical and thermal properties of wood plastic composites

Hybrid filler reinforced composites are considered as a high performance materials, but limited numbers of researches on hybridizations of wood fibers and mineral fillers were reported. Generally, high amount of filler content in composites can lead to the reduction of interfacial adhesion between matrix polymer and fillers, and it limits their applications. In this study, we measured the changes of tensile strength, water absorption, and thermal properties of composites after chemical treatments to wood fibers and mineral fillers. Coupling agent had its own optimum amount for wood fibers and talc to obtain the highest tensile strength. Talc addition showed little effect of the tensile strength with alkali treated wood fibers. Talc addition and silane treatment showed opposite effects on water absorption. Melting enthalpy was decreased by addition of the fillers because of the reduced amount of the crystallizable resin and because of the interference of the fillers for crystallization process.     

Surface modification and adhesion mechanisms in woodfiber-polypropylene composites

The interfacial adhesion between wood fiber and thermoplastic matrix polymer plays an important role in determining the performance of wood-polymer composites. The objectives of this research were to elucidate the interaction between the anhydride groups of maleated polypropylene (MAPP) and hydroxyl groups of wood fiber, and to clarify the mechanisms responsible for the interfacial adhesion between wood fiber and polypropylene matrix. The modification techniques used were bulk treatment in a thermokinetic reactive processor and solution coating in xylene. FT-IR was used to identify the nature of bonds between wood fiber and MAPP. IGC and wood veneer pull-out test was used to estimate the interfacial adhesion. Mechanical properties of injection molded woodfiber-polypropylene composites were also determined and compared with the results of esterification reaction and interfacial adhesion tests. Confocal Microscopy was employed to observe the morphology at the wood fiber-polypropylene interface, and the dispersion and orientation of wood fiber in the polypropylene matrix, respectively. The effectiveness of MAPP to improve the mechanical properties (particularly the tensile strength) of the composites was attributed to the compatibilization effect which is accomplished by reducing the total wood fiber surface free energy, improving the polymer matrix impregnation, improving fiber dispersion, improving fiber orientation, and enhancing the interfacial adhesion through mechanical interlocking. There was no conclusive evidence of the effects of ester links on the mechanical properties of the composites.     

Interactions at fiber/matrix interface in short fiber reinforced amorphous thermoplastic composites modified with micro- and nano-fillers

This study aims at systematically extracting fiber/matrix interfacial strength in short-glass fiber-reinforced polymer composites using an experimental micromechanics approach which employs mechanical properties and residual fiber length distributions to derive the apparent interfacial shear strength. We started from neat high-impact polystyrene matrix short-glass fiber-reinforced composites (HIPS/GF) with varying fiber loading and proceeded toward HIPS/GF hybrid composites containing micro- and nano-fillers where complex fiber/matrix interfacial interactions exist. It was found that apparent interfacial shear strength does not vary with fiber content, while the presence of fillers with different length-scales alters fiber/matrix interactions depending on their influence on physical properties of the polymer matrix, particularly in the vicinity of reinforcing fiber surfaces.     

Micromechanical deformation processes in PP/wood composites: Particle characteristics,adhesion, mechanisms

Polypropylene (PP) was reinforced with four natural fillers having different particle characteristics. Interfacial adhesion was changed by the introduction of maleated polypropylene (MAPP). The properties of the studied PP/wood composites depended strongly on interfacial adhesion and on the particle characteristics of the wood. Coupling with functionalized polymer is necessary for the preparation of composites with acceptable properties if the size of the particles is large and their aspect ratio is small. The effect of adhesion is smaller for particles with large aspect ratio. Several micromechanical deformation processes may occur in PP/wood composites including matrix yielding, debonding, fiber pull-out and fiber fracture both parallel and perpendicular to the fiber axis. The processes are competitive and may take place simultaneously and/or consecutively. The inherent properties of the reinforcement may limit the improvement of composite strength. Micromechanical deformation processes determine composite properties irrespectively of their mechanism.     

Lignocellulosic fibre mediated rubber composites: An overview

The rising concern towards the reduction in the use of petroleum-based, non-renewable resources and the need for more versatile polymer-based composite materials have led to increasing interests on natural polymer composites filled with natural organic fillers, i.e. coming from renewable and biodegradable sources. This paper reviews wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composites, cellulosic thermoplastic elastomers, nanocellulose based rubber nanocomposites, with the aims at providing the most state of the art information for directing further scientific research, possible commercialization and design of cellulosic rubber composites. It has been found that 1) the surface properties of natural cellulose, hence the compatibility and interface of the natural cellulose and matrix rubber/plastics, are crucial for the successful development of the composites, such, physical and chemical modification and additives have been widely attempted to improve the incompatibility and poor interfacial adhesion between the filler and matrix; 2) the curing characteristics, mechanical properties, thermal stability and morphologies of the composites are complex but closely related to not only the interfacial properties, but also the compositions (e.g. the concentration of cellulosic materials) and other processing parameters; 3) the nature of hydrophilic cellulosic and hydrophobic matrix rubber and/or plastics requires an accurate introduction of coupling agent, one end of its structure shall be compatible to hydrophilic and the other to hydrophobic. The reviews on the main paths and results of study on the advanced nanocellulose reinforced rubber nanocomposites and sandwiches indicate much potentials and needs for further in-depth studies.     

Analysis on dielectric loss characteristics of polyvinylidene fluoride and its composites

In this study, barium calcium zirconate titanate nanoparticles and nanofibers (denoted as BZT-BCT NPs and BZT-BCT NFs, respectively) were prepared by the sol–gel method and electrospinning, respectively. Under different temperatures and frequencies, the dielectric spectra of polyvinylidene fluoride (PVDF), BZT-BCT NPs, and BZT-BCT NFs composites were measured. On the basis of the experimental data, the polarisation activation energies of the polymer matrix interfacial polarisation and the dipole turn polarisation were calculated, and the basic polarisation characteristic parameters of the polymer matrix materials and fillers were obtained. Moreover, the effects of the filling phase and filling ratio on the dielectric properties of the composites were studied through applying BZT-BCT NPs and BZT-BCT NFs as the filling phases of the PVDF matrix and PVDF matrix composites. Furthermore, the double-layer low-density polyethylene (LDPE)/PVDF composites as well as the LDPE/PVDF composites uniformly mixed at a volume fraction of 1:1 were prepared, and the interfacial polarisation behaviours of the two materials were studied by dielectric spectroscopy to establish an effective analytical method so as to characterize interfacial polarisation established. The experimental results revealed as follows: interfacial polarisation was a significant mechanism of the polarisation behaviour of the composite materials; the fillers with different shape factors had varying effects on the dielectric constant of composites; meanwhile, the dielectric constant of the composite conformed to the predictions of the effective medium theory model.

     

热塑性聚合物/木纤维复合材料的研究进展

介绍了国内外关于热塑性聚合物／木纤维复合材料界面改性、在加工过程中木纤维的热稳定性以及阻燃性能等方面的研究进展，界面相容剂或偶联剂能大大提高其界面相容性，特别是马来酸酐接枝热塑性聚合物作为界面相容剂更为有效。硅烷偶联剂预处理木纤维表面对提高其热稳定性有一定的作用。     

The role of interfacial interactions on the glass-transition and viscoelastic properties of silica/polystyrene nanocomposite

Filler surface properties and polymer-filler interactions have dominate influence on viscoelastic behavior of polymeric matrix composites. When the filler-filler spacing is on the order of the polymeric matrix molecular size, fillers may agglomerate through direct short-range interactions, also by overlapping of interfacial layers of neighboring fillers. In this work the effect of interfacial layer on the viscoelastic properties of silica/polystyrene composite was investigated.The Si/Ps nanocomposites were prepared by solution mixing method, and dynamic rheometry was employed to determine the viscoelastic behavior in the melt state. Experimental results show that, addition of silica nanoparticles to polystyrene matrix would increase the glass-transition temperature of polymer. This increasing will be accelerated by presence of nanoparticles with more filler-polymer adhesion energy, because of more interfacial layer volume fraction. It is helpful in evaluating the volume fraction and equivalent thickness of interfacial layer in polymer nanocomposites. Likewise it is shown that, the dynamic moduli of nanocomposite is enhanced associated with the increase in the glass-transition temperature. This study implies that the main source of increment in both dynamic modulus and glass-transition temperature of polymer nanocomposites is the presence of the immobilized interfacial layer and the secondary filler network.     

Effect of various surface modifications of wood flour on the properties of PP/wood composites

Four different approaches were used for the modification of interfacial interactions in polypropylene (PP)/wood flour composites. We compare the effect of maleated polypropylene (MAPP), two surfactants (stearic acid and cellulose palmitate) and the chemical modification of wood (benzylation) on interfacial adhesion, homogeneity, processability and water absorption. Interfacial adhesion and reinforcement improves upon the addition of a maleated polymer as expected. Non-reactive surface modification leads to a moderate decrease of interaction, while benzylation decreases interfacial adhesion quite considerably. MAPP does not influence any other property of interest; homogeneity, viscosity and water absorption remain practically unchanged independently of the amount of coupling agent used. Surfactants improve homogeneity and processability, while the chemical modification of wood by benzylation decreases water absorption significantly. The results clearly prove that the proper selection of the approach and level of surface modification may lead to considerable improvement in targeted properties.     

界面改性增强塑木复合材料力学性能的研究进展

综述了国内外界面改性增强塑木复合材料力学性能的研究进展,包括界面改性增强的作用机理、木纤维的表面改性、塑料的表面改性和添加界面相容剂等,并展望了塑木复合材料界面改性研究的未来趋势。