短纤维补强氯丁橡胶的性能研究

研究短纤维种类和用量对短纤维/氯丁橡胶(CR)复合材料中短纤维取向和分散以及复合材料粘合性能和溶胀性能的影响.结果表明:随着短纤维用量的增大,短纤维/CR复合材料的相对交联密度和短纤维取向度均增大,抗溶胀性能提高,取向度大小顺序为芳纶短纤维、聚酯短纤维、锦纶66短纤维和短切棉纤维;聚酯纤维与CR基体的粘合性能最差,短切棉纤维在CR中分散性最差;短纤维/CR复合材料的性能呈现出明显的各向异性.     

短纤维在氯丁橡胶中的应用

研究了短纤维种类、用量及长度对短纤维/氯丁橡胶复合材料的纤维取向、纤维分散、力学性能、耐热性能以及溶胀性能的影响。结果表明,复合材料呈现明显的各向异性;3mm短纤维/氯丁橡胶(CR)复合材料的纤维取向度、拉伸强度、撕裂强度和耐溶胀性能均优于1mm复合材料,短纤维分散性对复合材料耐热性的影响较小。     

硅酸盐纳米纤维/氢化丁腈橡胶复合材料的性能

研究了热处理时间、偶联剂类型及用量和针状硅酸盐(FS)对硅酸盐纳米纤维/氢化丁腈橡胶(HNBR)复合材料性能的影响。结果表明,微米颗粒的FS在HNBR中能够被解离成纳米纤维,并具有优良的增强效果。FS/HNBR复合材料具有短纤维增强橡胶复合材料的应力-应变特性和各向异性,硅烷偶联剂的加入和热处理能够提高复合材料的力学性能。热处理10min、FS用量为50质量份、偶联剂选用KH-570且其用量为2质量份时复合材料的力学性能较好。     

硅酸盐纳米短纤维增强三元乙丙橡胶复合材料的结构与性能

用硅烷偶联剂改性针状硅酸盐(FS)与三元乙丙橡胶(EPDM)机械共混,制备了EPDM/改性FS复合材料,研究了FS在EPDM中的分散性,考察了偶联剂和改性FS用量、FS所含自由水对复合材料力学性能和各向异性的影响.结果表明,经过偶联荆改性的FS能够解离成纳米纤维均匀分散于EPDM中,每100份FS的偶联刺最佳用量为24份;EPDM/改性FS复舍材料具有短纤维增强橡胶复合材料的应力-应变特征和力学性能的各向异性,且随改性FS和偶联剂的用量增加,这种力学行为更加明显;FS中所舍自由水对复合材料的常温和高温拉伸性能有明显影响.     

基于纤维取向的纳米纤维滤料设计及其性能

通过基于霍夫变换的图像分析法获取静电纺纳米纤维取向分布信息,分析纤维取向对纳米纤维滤料性能的影响,并据此设计制备了中间为杂乱纤维层、两侧为相互垂直的取向纤维层构成的复合纳米纤维膜滤料。采用扫描电镜对纳米纤维膜形貌进行观察并获取SEM图像,进行了透气性、拉伸性能、孔径尺寸和过滤性能测试。结果表明,纳米纤维膜纤维分布方向拉伸断裂强度高,纤维取向各向异性比例理论值和实验值相吻合,纤维取向是影响纳米纤维膜力学各向异性的主要参数;取向纳米纤维膜滤料孔径较大且有许多微粒可逃逸的通道,其过滤效率和过滤阻力均较低,与文献中报道的数值模拟结果相一致;所设计制备的复合纳米纤维膜滤料结合了取向纳米纤维膜滤料力学性能优良和杂乱纳米纤维膜滤料过滤效率高的优点,其纵向和横向断裂强度分别为8.85MPa和8.71MPa,气流流速为25L/min时过滤效率高达99.691%。     

碳/碳复合材料中的微区结构和性能的研究

实验以Raman光谱、原位纳米力学测试、偏光显微镜和扫描电镜(SEM)对碳/碳复合材料不同微区的结构和性能进行研究,实验结果表明:碳/碳复合材料不同微区的结构和性能存在明显的差异性,不同微区的石墨化程度是沿着相邻纤维中心径向逐步增强,至纤维间的碳基体最高;碳基体以片层状结构沿纤维表面取向,呈同心圆环状,其光学各向异性远...     

直接共混法制备的针状硅酸盐复合材料的结构与性能研究

通过直接共混法制备出一种低成本、具有优良物理机械性能的AT／SBR新型复合材料。TEM和SEM分析表明大部分AT在常规机械剪切力作用下，可以剥离成纳米（100nm以下）针状纤维分散在SBR基体中，表现出较好的增强作用，改性剂的加入使这种作用更加显著。     

纳米凹凸棒土/氯丁橡胶复合材料耐磨性的研究

采用机械共混法制备了凹凸棒土（AT）/氯丁橡胶（CR）纳米复合材料,探讨了AT用量、改性剂种类及用量和硫化剂体系等对复合材料耐磨性能的影响,还观察了使用不同改性剂制备的复合材料阿克隆磨耗表面形态。结果表明,AT用量为30份时复合材料耐磨性最好;改性剂KH-550能显著提高硫化胶耐磨性,其最佳用量为AT用量的3%;硫化体系不同时复合材料的耐磨性有所不同,采用MgO/ZnO/DCP（质量比为4/5/1）并用硫化体系时复合材料耐磨性最好。     

纳米凹凸棒土改性聚氨酯纤维的热性能研究

用不同含量的纳米凹凸棒土(AT)改性聚氨酯(PU)纤维,研究了改性PU纤维热分解动力学,测定了分解活化能,讨论了AT对改性PU纤维热性能的影响。结果表明:AT的加入,提高了PU纤维的起始分解温度,改善了纤维的热稳定性;加入质量分数为1.5%的AT,改性PU纤维的起始分解温度相比纯PU纤维提高了近14℃,增强了PU硬段的热分解稳定性。     

裂解碳包覆对SiC纳米纤维增强SiC陶瓷基复合材料性能的影响

以SiC纳米纤维(SiC_nf)为增强体,通过化学气相沉积在SiC纳米纤维表面沉积裂解碳(PyC)包覆层,并与SiC粉体、Al₂O₃-Y₂O₃烧结助剂共混制备陶瓷素坯,采用热压烧结工艺制备质量分数为10%的SiC纳米纤维增强SiC陶瓷基(SiC_nf/SiC)复合材料。研究了PyC包覆层沉积时间对SiC_nf/SiC陶瓷基复合材料的致密度、断裂面微观形貌和力学性能的影响。结果表明:在1 100 ℃下沉积60 min制备的PyC包覆层厚度为10 nm,且为结晶度较好的层状石墨结构;相比于纤维表面无包覆层的复合材料,复合材料的断裂韧性提高了35%,达到最大值(19.35±1.17) MPa·m^1/2,抗弯强度为(375.5±8.5) MPa,致密度为96.68%。复合材料的断裂截面可见部分纳米纤维拔出现象,但SiC_nf/SiC陶瓷基复合材料界面结合仍较强,纳米纤维拔出短,表现为脆性断裂。     

Structure and mechanical properties of nanodispersed fibrous silicate‐reinforced ethylene–propylene–diene monomer nanocomposites

In this study, ethylene–propylene–diene monomer (EPDM)/fibrillar silicate (FS) nanocomposites were successfully prepared by mechanically blending EPDM with FS, which was modified by silane coupling agent KH570 containing methacryloxy group. The effects of silane content and modified FS on the dispersion of FS and mechanical properties of the composites were investigated. The impact of water in FS on mechanical properties of the composites was also evaluated. The results showed that modified FS could be dissociated into nanofibers dispersing evenly in the EPDM matrix by increasing substantially the loading of silane through the mechanical blending. The optimum loading level of silane coupling agent was up to 24 phr/100 phr FS. Silane KH570 could improve the dispersion of FS and strengthen nanofibers–rubber interfacial adhesion even at the loading of as high as 50 phr FS, making FS to exhibit excellent reinforcement to EPDM. Too much FS could not be completely dissociated into nanofibers, slowing down further improvement. The EPDM/FS composites exhibited the similar stress–strain behavior and obvious mechanical anisotropy with short microfiber‐reinforced rubber composites. With the increase in silane coupling agent and modified FS, the number of nanofibers increased because of the exfoliation of FS microparticles; thus, the mechanical behaviors would become more obvious. It was suggested that the free water in FS should be removed before mechanically blending EPDM with FS because it obviously affected the tensile properties of the composites. Regardless of whether FS was dried or modified, the EPDM/FS composites changed little in tensile strength after soaked in hot water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Bis-GMA/TEGDMA Dental Composites Reinforced with Electrospun Nylon 6 Nanocomposite Nanofibers Containing Highly Aligned Fibrillar Silicate Single Crystals

The objective of this research was to study the reinforcement of electrospun nylon 6/fibrillar silicate nanocomposite nanofibers on Bis-GMA/TEGDMA dental composites. The hypothesis was that the uniform distribution of nano-scaled and highly aligned fibrillar silicate single crystals into electrospun nylon 6 nanofibers would improve the mechanical properties of the resulting nanocomposite nanofibers, and would lead to the effective reinforcement of dental composites. The nylon 6/fibrillar silicate nanocomposite nanofibers were crystalline, structurally oriented and had an average diameter of approximately 250 nm. To relatively well distribute nanofibers in dental composites, the nanofiber containing composite powders with a particle structure similar to that in interpenetration networks were prepared first, and then used to make the dental composites. The results indicated that small mass fractions (1% and 2%) of nanofiber impregnation improved the mechanical properties substantially, while larger mass factions (4% and 8%) of nanofiber impregnation resulted in less desired mechanical properties.     

Printability,shape-memory,and mechanical properties of PHB/PCL/CNFs composites

Shape-memory polymers have attracted attention as smart implant materials in recent years because they are lightweight, low-cost, easily processable, and because they undergo large deformation. Here, cellulose nanofibers (CNFs) were used as a reinforcement for polyhydroxybutyrate (PHB)/polycaprolactone (PCL) composites to improve mechanical properties. The composites were investigated by rheological tests, differential scanning calorimetry, dynamic mechanical analysis, mechanical property tests, and shape-memory tests. The printability of PHB/PCL/CNFs composites was demonstrated by using them to print interconnected porous structures with a gyroid surface. The results showed that the PHB/PCL (80:20) composites with 1 wt% CNF displayed the best comprehensive mechanical and shape-memory properties. As a functional verification, a model of the self-opening hand was fabricated by 3D printing, and its deformation and recovery capabilities were evaluated.     

Dispersion of soybean stock‐based nanofiber in a plastic matrix

The focus of this work is the study of the dispersion mechanism of soybean stock‐based nanofibers in a plastic matrix. The cellulose nanofibers were extracted from soybean stock by chemo‐mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 and 100 nm and lengths of thousands of nanometers. These nanofibers were characterized by atomic force microscopy and transmission electron microscopy. X‐ray diffraction studies showed that the soybean stock nanofibers had a relative percentage crystallinity of about 48%. Selective chemical treatments increased the cellulose content of soybean stock nanofibers from 41 to 61%. The matrix polymers used in this project were poly(vinyl alcohol) (PVA) and polyethylene (PE). The mechanical properties of nanofiber‐reinforced PVA film demonstrated a 4‐ to 5‐fold increase in tensile strength, as compared to the untreated fiber‐blend‐PVA film. One of the problems encountered in the use of nanoreinforcements lies in the difficulty in ensuring good dispersion of the filler in the composite material. Improved dispersion level of nanofibers within a thermoplastic was achieved by adding ethylene‐acrylic oligomer emulsion as a dispersant. In the solid phase of nanofiber‐blend‐PE composites, the compression‐molded samples showed that improved mechanical properties were achieved with coated nanofibers. Copyright © 2006 Society of Chemical Industry     

Electrophoretic deposition of different carbon nanoscale reinforcements on carbon fiber fabrics and mechanical properties of the resulting hybrid multi‐scale epoxy composites

Three types of carbon nanoscale reinforcements (CNRs) including the shortened electrospun carbon nanofibers (ECNFs, with diameters and lengths of ∼200 nm and ∼15 µm, respectively), carbon nanofibers (CNFs), and graphite nanofibers (GNFs) were electrophoretically deposited on carbon fiber (CF) fabrics for the fabrication of hybrid multi‐scale epoxy composites. The results indicated that the electrophoretic deposition (EPD) of CNRs onto CF fabrics led to substantial improvements on mechanical properties of hybrid multi‐scale epoxy composites; in particular, the hybrid multi‐scale epoxy composite containing surface‐functionalized ECNFs (with amino groups) exhibited the highest mechanical properties. The study also indicated that some agglomerates of CNRs (particularly GNFs) could form during the EPD process, which would decrease mechanical properties of the resulting composites. Additionally, the reinforcement mechanisms were investigated, and the results suggested that continuous (or long) ECNFs would outperform short ECNFs on the reinforcement of resin‐rich interlaminar regions in the composites. POLYM. COMPOS., 35:1229–1237, 2014. © 2013 Society of Plastics Engineers     

聚丙烯接枝马来酸酐对聚丙烯/凹凸棒石复合体系力学性能的影响

使用聚丙烯接枝马来酸酐(PP-g-MAH)对聚丙烯(PP)/凹凸棒石(AT)复合体系进行了增容,研究了PP-g-MAH对PP/原矿AT和PP/钛酸酯偶联剂改性AT复合体系力学性能的影响,观察了AT在PP中的分散状态以及PP/AT复合体系的断面形貌.结果表明P-g-MAH对AT在PP中分散状态没有明显影响;但加入5%的PP-g-MAH能够改善PP与原矿AT的相容性,提高PP/原矿AT复合体系的力学性能;加入PP-g-MAH对PP/钛酸酯偶联剂改性AT复合体系力学性能的改善不明显.     

Organic functionalization of carbon nanofibers for composite applications

The present work reports the study of the effect of different chemical functionalization methods on the interfacial characteristics of the polymer composites formed. The chemically modified carbon nanofibers were blended with polypropylene (PP) and PP modified with maleic anhydride on a mini twin‐screw extruder. The functionalization methods were designed for minimum fiber damage and enhanced fiber/matrix interactions by chemical reaction of the functional groups introduced at the nanofibers surface with the maleic anhydride grafted at the PP. The degree of nanofiber functionalization was studied using thermogravimetric analysis. The composites were analyzed for nanofiber dispersion, mechanical properties, and electrical resistivity. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Melt‐processed polyaniline nanofibers/LDPE/EAA conducting composites

The melt‐processable polyaniline nanofibers doped with superfluous dodecylbenzenesulfonic acid (PANI‐DBSA) were synthesized using the interfacial polymerization and thermal doping technique. Conducting composites composed of PANI‐DBSA nanofibers, low‐density polyethylene (LDPE), and ethylene‐acrylic acid copolymer (EAA) as compatibilizer were prepared by melt processing. The effects of PANI‐DBSA nanofibers on the electrical conductivity, and mechanical properties, and morphological structure of the composites were investigated. As a result, the conducting composites had lower percolation threshold (4 wt%) due to the easy formation of conducting paths for fibrillar‐like PANI‐DBSA in the LDPE matrix, which was also confirmed by the frequency dependence of the real part of the AC conductivity. The Scanning electron microscopy (SEM) images indicated that the PANI‐DBSA nanofibers were dispersed uniformly in the matrix. The mechanical properties of the composites were improved at the low PANI‐DBSA load (about 1 wt%), but they were deteriorated at high PANI‐DBSA content. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Mechanical analysis of carbon nanofiber/epoxy resin composites

The mechanical response of epoxy resins filled without treated carbon nanofibers and carboxylated ones has been evaluated through tensile tests. The elastic properties did not improve compared to the neat epoxy resin regardless of filler content or functionalization treatment, while the tensile strength and the elongation at break were reduced for the highest filler content (1 wt%). Fractographic analysis showed that composites reinforced with carboxylated nanofibers showed better filler dispersion than those without treatment. However, in both cases, the fibers tended to agglomerate and the formation of porosity was favored. The size of bundles of nanofibers rose with the content of nanofiller and for the same addition of carbon nanofibers, the size and distribution was respectively bigger and wider for the untreated carbon nanofibers‐reinforced composites than for the carboxylated carbon nanofiber‐reinforced composites. These defects degraded the mechanical response. The dilute suspension of clusters model was applied to estimate the elastic properties, showing agreement with the experimental results. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers