橡胶粒子和刚性纳米粒子对注塑级硬质聚氯乙烯复合材料断裂行为的影响

采用核壳型丙烯腈-苯乙烯-丁二烯共聚物(ABS)和纳米碳酸钙(CaCO3)协同改性聚氯乙烯(PVC),制备了注塑级硬质PVC纳米复合材料.通过透射电镜(TEM)、扫描电镜(SEM)、力学性能测试研究了其结构与性能,并采用有限元模拟方法研究了ABS与纳米CaCO3粒子对复合材料断裂行为的影响.当CaCO3含量低于12 p...     

MMA接枝改性PVC/CaCO3纳米复合材料的力学性能

采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC（PVC/CaCO3）复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好.     

一种纳米氧化锌复合生物基水性聚氨酯的合成和性能研究

以自制的生物基水性聚氨酯(APU)及纳米氧化锌(ZnO)为原料制备了APU/ZnO复合材料,并通过红外光谱(FT-IR)、热重(TG)、紫外(UV)、透射电镜(TEM)和扫描电镜(SEM)等手段对复合材料的性能进行了表征。TEM和SEM照片显示,制得的新型纳米ZnO的尺寸为200 nm左右,可较均匀地分散在APU体系中。TG测试结果表明添加了少量纳米ZnO的复合材料的耐热性有了明显提高。同时测试结果表明,少量纳米ZnO粒子的加入对APU有很好的增强和增韧效果,且具有一定的抗菌性和抗紫外性能。     

纳米级CaCO_3粒子与弹性体CPE微粒同时增韧PVC的研究

研究了平均粒径为 30nm的超细级纳米CaCO3 与氯化聚乙烯 (CPE)对聚氯乙烯 (PVC)共混体系二元协同增韧效应及机制 .结果表明 ,当共混体系中有一定量的CPE时 ,纳米CaCO3 的加入可以明显地提高共混物的韧性 ,而不降低共混物的强度和刚性 .纳米CaCO3 在PVC基体中达到了纳米级的分散 .当纳米CaCO3 的用量为 8份 (质量 )时 ,PVC CPE 纳米CaCO3 共混物的冲击断面产生了大量的有规则的网丝状结构 ,共混物的缺口冲击强度达到 81 1kJ m2 ,比不加纳米CaCO3 的共混体系高 7 3倍 .CPE的加入对共混体系的加工流动性能无影响 ,纳米CaCO3 的加入使共混体系的加工流动性能变差     

纳米CdS/聚乙烯咔唑(PVK)复合材料制备与表征

采用反相微乳法在庚烷/琥珀酸二异辛酯磺酸钠(AOT)/水体系中成功制备出纳米CdS/聚乙烯咔唑(PVK)复合材料。通过紫外-可见光谱(UV-Vis)、X射线衍射(XRD)、透射电子显微镜(TEM)、荧光光谱(PL)对复合材料进行了结构表征和形貌观察。结果表明,UV-Vis光谱吸收峰在325 nm和360 nm,表现出纳米粒子明显的量子尺寸效应;TEM照片显示纳米CdS粒径分布较窄,均匀分散在PVK中。XRD分析表明,CdS纳米颗粒已经形成。PL结果显示:产物的荧光发射光谱峰波长在375 nm和520 nm。     

SBA/PVC复合树脂的制备与表征

采用聚丙烯酸正丁酯(PBA)改性的丁苯(SBR)胶乳为种子乳液(SBA),通过乳液接枝共聚氯乙烯制备了SBA/PVC复合树脂.通过粒径分析仪、动态力学分析仪(DMA)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)等测试手段,表征了复合胶乳粒的粒径与形态,以及材料的形态结构.粒径分析表明PVC确实包覆在SBA上;TEM研究结果显示SBA/PVC胶乳粒子呈现明显的核壳结构,PBA加入可提高SBR在复合材料中的分散性;DMA分析表明SBA/PVC复合树脂在低温区呈现了一个宽而弱的转变峰,揭示了接枝过渡层的微观结构特征;研究了交联剂和PBA用量对材料性能的影响,结果表明在PBA含量较低时,SBA/PVC复合树脂就显示了优良的冲击性能,且SEM照片显示材料断面形貌为特征性韧性断裂.     

用于高效去除水中孔雀石绿的三层结构磁性复合材料Fe3O4@聚丙烯酸@ZiF-8的制备

设计并合成了一种以磁性纳米粒子为核,聚合物为中间层,金属有机骨架材料为外层的三层结构磁性复合材料(Fe₃O₄@PAA@ZIF-8)。首先利用溶剂热法制备Fe₃O₄纳米粒子,然后通过蒸馏沉淀聚合法在Fe₃O₄纳米粒子表面包覆聚丙烯酸(PAA)层,最后通过原位沉积法在PAA外部包覆ZIF-8。在对Fe₃O₄@PAA@ZIF-8的组成和结构进行表征的基础上,深入研究其对孔雀石绿(MG)的吸附性能。透射电子显微镜(TEM)显示Fe₃O₄@PAA@ZIF-8具有明显的三层结构,Fe₃O₄的平均粒径为117nm,PAA层厚度约为17 nm,ZIF-8层的厚度约为14 nm。Fe₃O₄@PAA@ZIF-8对MG的吸附量随着p H的升高而增大,吸附过程符合准二阶动力学模型和Langmuir等温吸附模...     

聚丙烯/PMMA/CaCO3纳米复合材料的制备、结构与力学性能

分别将经不同表面处理的纳米碳酸钙粒子与聚合物PP共混,制备PP／CaCO3和PP／PMMA／CaCO3纳米复合材料。用TEM观察了表面处理后纳米粒子的粒径与分散情况,发现复合粒子分散较均匀。用DSC与WAXD研究了复合材料的结晶行为,发现原位聚合制备的PMMA／CaCO3纳米复合粒子与PP共混后,PP有异相成核作用,出现了不稳定的PPβ晶型。PP／PMMA／CaCO3纳米复合材料力学性能有大幅度的提高。     

基于表面修饰聚丙烯酸合成超顺磁/荧光纳米复合粒子

在聚丙烯酸修饰的Fe₃O₄纳米粒子表面共价结合罗丹明B, 获得分散性和荧光信号均得到改善的超顺磁/荧光复合纳米材料. 分别用透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)、热重分析仪、荧光光谱仪、X射线衍射仪(XRD) 和振动样品磁强计(VSM) 对合成的粒子进行了表征. 结果表明, 羧基化的Fe₃O₄纳米粒子和Fe₃O₄-荧光纳米复合材料的粒径基本相同, 为6～10 nm. Fe₃O₄-荧光纳米复合材料的饱和磁化强度为39.2 A•m²/kg, 室温下呈现超顺磁性, 具有较强的荧光信号.     

粒子尺寸与表面改性对PPDO/CaCO3复合材料机械性能的影响

选用三种CaCO3粒子[纳米粉料(nano-CaCO3,记为CC1),晶须(CaCO3 wisker,记为CC2)和偶联剂处理的晶须(silane coated CaCO3 wisker,记为CC3)]在有机溶液中与聚对二氧环己酮(PPDO)通过溶液共混制得三种不同的PPDO/CaCO3复合材料——PPDO/CC1,PPDO/CC2和PPDO/CC3.力学性能测试发现,PPDO/CC2的拉伸强度较PPDO大幅提高;但CC3与PPDO的相容性变差,导致PPDO/CC3的力学性能明显下降.     

Morphology and properties of cyanate ester/liquid polyurethane/silica nanocomposites

The high‐speed homogeneous shearing method was applied to prepare nanocomposites of cyanate ester (CE) with liquid polyurethane elastomer (PUR) and silica. To investigate the influence of various components on the morphology and properties of the ternary composites, the binary composites of CE/PUR and CE/silica were also involved in this article. The morphology of the cured materials of binary and ternary systems was investigated by transmission electron microscopy (TEM), and the results show that silica nanoparticles were uniformly distributed in the ternary and binary matrix. Phase separation of elastomer in composites was not observed by TEM. FTIR test and dynamic mechanical analysis (DMA) proved that chemical linking was existent between PUR and CE. Scanning electron microscopy examinations and mechanical properties tests were carried out. The results show that ternary composites displayed higher fracture toughness and impact strength compared with most of the binary systems. This suggests that the addition of PUR and nanosilica can synergistically improve the toughness of CE. DMA studies confirmed that the incorporation of silica can increase the storage modulus and T_g for CE and CE/PUR system, since there are a good adhesion and a strong hydrogen bonding between silica and polymers. The thermal property of ternary composites increases with the increase of silica nanoparticle loading. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1243–1251, 2008     

羟基不饱和脂肪酸改性纳米碳酸钙对聚丙烯微观形态和流变性能的影响

采用羟基不饱和脂肪酸,通过固相法对硬脂酸改性的工业纳米碳酸钙CCR进行表面改性制备了R-CCR,红外光谱(FTIR)显示改性剂已结合在碳酸钙表面.通过熔融共混法制备了聚丙烯(PP)/乙丙橡胶(EPDM)/纳米碳酸钙二元和三元复合材料.并利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察复合材料的微观形态,发现R-CCR的加入,使PP复合材料的拉伸断面出现明显的拉丝状结构和大面积的屈服变形,与PP/EPDM/CCR相比,PP/EPDM/R-CCR冲击断面的空穴明显增加并细化,R-CCR在PP基体中分散均匀,且界面模糊,与基体的相容性明显优于CCR.复合材料流变行为的研究表明R-CCR的加入,体系储存模量G′和损耗模量G″随频率的增加而增加,对损耗因子和复数粘度的影响不大;但PP/EPDM/R-CCR复合材料的表观粘度,明显低于PP/EPDM/CCR和纯PP,同时,剪切速率的增加可有效降低体系的表观粘度.力学性能表明,R-CCR对PP同时起到增韧和增强的效果.且R-CCR和EPDM对PP具有协同增韧的效果.在保持聚丙烯的模量和强度基本不变的前提下,大幅度的改善聚丙烯的韧性,同时加工性能保持不变.     

Poly (vinyl chloride)/poly (α‐methylstyrene–acrylonitrile)/acrylic resin ternary blends with enhanced toughness and heat resistance

In this study, tough and high heat‐resistant poly (vinyl chloride) (PVC)/poly (α‐methylstyrene–acrylonitrile) (α‐MSAN) blends (70/30) containing acrylic resin (ACR) as a toughening modifier was prepared. With the addition of ACR, heat distortion temperature increased slightly, which corresponded with the increase in glass transition temperature measured by differential scanning calorimetry and dynamic mechanical thermal analysis. Thermogravimetric analysis showed that addition of ACR improved the thermal stability. With regard to mechanical properties, tough behavior was observed combined with the decrease in tensile strength and flexural strength. A brittle‐ductile transition (BDT) in impact strength was found when ACR content increased from 8 to 10 phr. The impact strength was increased by 34.8 times with the addition of 15 phr ACR. The morphology correlated well with BDT in impact strength. It was also suggested from the morphology that microvoids and shear yielding were the major toughening mechanisms for the ternary blends. Our present study offers insight on the modification of PVC, since combination of α‐MSAN and ACR improves the toughness and heat resistance of pure PVC simultaneously. Copyright © 2011 John Wiley & Sons, Ltd.     

Flammability and thermal degradation of flame retarded polypropylene composites containing melamine phosphate and pentaerythritol derivatives

The flammability of polypropylene (PP) composites containing intumescent flame retardant additives, i.e. melamine phosphate (MP) and pentaerythritol (PER), dipentaerythritol (DPER) or tripentaerythritol (TPER) was characterized by limiting oxygen index (LOI), UL 94 and the cone calorimeter, and the thermal degradation of the composites was studied using thermogravimetric analysis (TG) and real time Fourier transform infrared (RTFTIR). It has been found that the PP composite containing only MP does not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composite, the LOI values of the PP/MP/PER (PP/MP/DPER or PP/MP/TPER) ternary composites at the same additive loading are all increased, and UL 94 ratings of most ternary composites studied are raised to V-0 from no rating (PP/MP). The cone calorimeter results show that the heat release rate and smoke emission of some ternary composites decrease in comparison with the binary composite. It is noted from the TG data that initial decomposition temperatures of ternary composites are lower than that of the binary composite. The RTFTIR study indicates that the PP/IFR composites have higher thermal oxidative stability than the pure PP.     

Performance of high-temperature thermosetting polyimide composites modified with thermoplastic polyimide

The preparation of polyimide (PI) resin with high heat resistance and toughness is a significant challenge. In this study, thermoplastic PI (TPI) was used to toughen thermosetting PIs, and toughened PI (TPI/PI) blends were prepared. The modified PI resin system exhibited good thermal stability, excellent heat resistance, and high toughness. The results indicated that the TPI/PI blends maintained the curing behavior and characteristics of the PI oligomer. The T_g of the cured TPI/PI blend exceeded 395 °C, and the T_5% values were in the range of 533–563 °C, suggesting excellent thermal stability and heat resistance. The maximum impact strength was increased by 46% compared with that of pure PI, indicating the excellent toughening effect of the TPI. Carbon fiber-reinforced PI composites were prepared using the toughening system as a matrix. The compression-after-impact values of the carbon fiber-reinforced PI composites were up to 190 MPa, indicating the excellent toughness of the materials.     

Complementary effects of multiwalled carbon nanotubes and conductive carbon black on polyamide 6

This article introduces a newly innovative idea for preparation of superconductive ternary polymeric composites of polyamide 6 (PA6), conductive carbon black (CCB), and multiwalled carbon nanotubes (MWCNTs) with different weight ratios by a melt‐mixing technique. The complementary effects of CCB and MWCNTs at different compositions on rheological, physical, morphological, thermal, and dynamic mechanical and electrical properties of the ternary composites have been examined systematically. We have used a novel formulation to produce high‐weight fraction ternary polymer composites that show extremely higher conductivity when compared with their corresponding binary polymer composites at the same carbon loading. For example, with an addition of 10 wt % MWCNTs into the CCB/PA6 composite preloaded with 10 wt % CCB, the electrical conductivity of these ternary composites was about 5 S/m, which was 10 times that of the CCB/PA6 binary composite (0.5 S/m) and 125 times that of the MWCNT/PA6 binary composite (0.04 S/m) at 20 wt % carbon loading. The incorporation of the MWCNTs effectively enhanced the thermal stability and crystallization of the PA6 matrix in the CCB/PA6 composites through heterogeneous nucleation. The MWCNTs appeared to significantly affect the mechanical and rheological properties of the PA6 in the CCB/PA6 composites, a way notably dependent on the MWCNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1203–1212, 2010     

部分水解聚甲基丙烯酸甲酯/氢氧化钙复合物对硬质聚氯乙烯热稳定性与透明性及塑化行为的影响

采用溶液沉淀法制备了部分水解的聚甲基丙烯酸甲酯(h-PMMA)/氢氧化钙(Ca(OH)2)复合物.采用X-射线衍射(XRD)、红外光谱(FTIR)、等离子体发射光谱和差示扫描量热表征了h-PMMA/Ca(OH)2复合物的组成与结构;采用刚果红测试、动态热稳定测试和热失重分析(TGA)研究了复合物对聚氯乙烯(PVC)的热稳定效果;通过紫外-可见(UV-Vis)光谱、扫描电镜(SEM)照片和熔融塑化曲线研究了复合物对PVC透明性和塑化行为的影响.结果表明,在Ca(OH)2晶体生长过程中,h-PMMA通过—COO-/Ca2+离子配位作用吸附于Ca(OH)2表面,不仅限制了Ca(OH)2粒子尺寸,且有助于Ca(OH)2在PVC中均匀分散.所得h-PMMA/Ca(OH)2复合物在显著提高PVC热稳定性和塑化能力的同时,还使PVC保持透明性.     

Structures and Mechanical Properties of PVC／Na^＋—Montmorillonite Nanocomposites

Poly(viyl chloride)/Na^ -montmorillonite(PVC/MMT)nanocomposites with different MMT contents were prepared via melt blending.Wide-angle X-ray diffraction(WAXD)and transmission electron microscopy(TEM)were used to characterize the structures.Effects of MMT content on the mechanical properties were also studied.It is found that PVC molecular chains can intercalate into the gallery of MMT layers during melt blending process,the stiffiness and toughness of the composites are inproved simultaneously within 0.5-7wt% MMT content,and the transparency and mechanical properties decrease as MMT conten further increases.     

Enhancement of thermal conductivity and tensile strength of liquid silicone rubber by three-dimensional alumina network

ABSTRACT

Rapidly increasing demands for higher integration density and stability of electronic devices embrace higher requirements for thermally conductive silicone rubber, which is promisingly used in ultra-thin components. In this work, alumina whiskers (AWs) and alumina flakes (AFs) are used to modify liquid silicone rubber (LSR) by fabricating binary (AFs/LSR) or ternary (AWs/AFs/LSR) composites. The thermal conductivity and mechanical strength of the binary and ternary composites were investigated. Thermal conductivity of the binary AFs/LSR composite (25AFs/LSR) was 0.1990 W m^?1 K^?1, while the thermal conductivity of the ternary AFs/AWs/LSR composite (20AFs/5AWs/LSR) was 0.2655 W m^?1 K^?1. Furthermore, the tensile strength of the ternary AWs/AFs/LSR composites increased by 180.9% as compared with the binary system, increased to 7.81 MPa from 2.78 MPa due to the introduction of 1 wt% AWs. As a reason, a significant synergistic effect of AWs and AFs in the enhancement of both thermal and mechanical properties of the LSR was proved. Furthermore, the dielectric property measurements demonstrated that the ternary composites exhibited a lower dielectric constant and dielectric loss, indicating that the AWs/AFs/LSR composites were qualified to be applied in the field of electronic devices.