反应型有机修饰剂对环氧树脂/粘土纳米复合材料热/机械性能的影响

使带有环氧基团的三缩水甘油基对氨基苯酚(TGPAP)分别与溴代正丁烷(BB)、2-溴乙醇(BE)反应,合成了反应型粘土有机修饰剂溴化(正定烷基)双环氧基(4-环氧醚基)铵(TGPAPB)和溴化(2-羟乙基)双环氧基(4-环氧醚基)铵(TGPAPE)。用这两种修饰剂改性粘土,分别制备出具有相同反应官能团但与环氧树脂的相容性略有不同的两种有机化粘土(B-Clay和E-Clay)。再用“粘土淤浆复合法”制备出两种环氧树脂/粘土纳米复合材料,研究了两种反应型有机修饰剂对纳米复合材料的结构和性能的影响。结果表明：带有羟基的E-Clay以高度无规剥离形式均匀分布在环氧树脂基体中;而B-Clay则形成了无规剥离/插层混合结构。两种粘土均参与固化反应在环氧树脂基体和粘土片层间产生了较强的界面作用力,从而显著提高了纳米复合材料的拉伸强度。粘土质量分数为3%的两种纳米复合材料,其拉伸强度分别达到32.4 MPa(E-Clay)和28.0 MPa(B-Clay),比对应的纯环氧树脂聚合物分别提高了76.47%和52.51%。同时,这两种纳米复合材料的玻璃化转变温度(T_g)也略有提高。     

聚合物表面纳米蛾眼结构的紫外压印制备工艺及抗反射性能

利用滚对平板(RTP)紫外纳米压印工艺在聚合物薄膜表面成功制备出大面积蛾眼纳米结构。通过原子力显微镜观测,可以看出蛾眼纳米结构在聚合物表面排布比较规整,呈乳状凸起阵列排布。蛾眼结构波峰高度复制率可以达到95.2%,表面微结构填充完整,复制效果良好。与单层镀膜(AR-coating)抗反射材料相比,抗反射蛾眼结构反射率测试结果在可见光波段(380~760nm)反射率平均降到3%。视角在110°左右可见光平均反射率为7%。     

聚碳酸酯/羟基磷灰石纳米复合材料的力学性能与热性能

采用低剪切应力分散混合方法制备了不同含量的聚碳酸酯/羟基磷灰石纳米复合材料(PC/HAP),并研究了其力学性能和热行为。结果表明:采用低剪切应力法复合加入的HAP在基体中分散均匀但界面结合较弱,材料的屈服强度略有提高,而冲击性能有一定程度下降;对PC与PC/HAP复合材料在空气中热降解动力学的研究表明:在空气气氛中PC与PC/HAP均呈现二阶失重,HAP可显著提高材料的最大热失重温度及热稳定性,一阶热降解活化能由109 kJ/mol上升到186 kJ/mol,二阶热降解活化能由127 kJ/mol上升到195 kJ/mol。     

疏水耐环境型SiO2/TiO2/SiO2-TiO2太阳能宽光谱增透膜的制备及性能研究

利用TFCcal设计软件构建膜系结构, 采用溶胶-凝胶工艺和提拉法在超白玻璃上制备出厚度精确可控的宽光谱、高增透型SiO₂/TiO₂/SiO₂-TiO₂减反膜, 同时结合甲基三乙氧基硅烷(MTES)改性碱催化的SiO₂溶胶, 通过提拉法一次制备出高透过率疏水型薄膜。研究表明, 高增透型三层宽光谱减反膜的理论膜层厚度依次为: 80.9 nm(内层SiO₂-TiO₂)、125.0 nm(中间层TiO₂)、95.5 nm(外层SiO₂), 其在400~700 nm可见光范围内平均透过率实际可高达97.03%以上。多层膜经过退火处理后, 膜面的水接触角高达131.5°, 同时陈化两个月以后的多层膜透过率仅下降0.143%, 表明制备的SiO₂/TiO₂/ SiO₂-TiO₂多层减反膜具有优良的疏水和耐环境性能。     

PET/SiO2纳米复合纤维的力学性能和微观结构

考察了纳米SiO2对PET纤维力学性能的影响,并采用WAXD、FT-IR、DSC、双折射等手段对纤维的微观结构进行了表征。研究表明,纳米SiO2的加入提高了PET纤维的力学性能,且PET/SiO2纳米复合纤维在结晶度略有降低的情况下,非晶区取向度明显提高。非晶区取向度的提高是PET/SiO2纤维力学性能提高的根本原因。     

针形纳米碳酸钙的表面改性及在PVC中的应用

对自制直径为30 nm~40 nm,长径比10~15的针形纳米碳酸钙进行表面改性后,将其应用于聚氯乙烯(PVC)的改性研究中,考察了改性针形纳米碳酸钙/PVC复合材料的力学性能。与未填充的PVC相比,纳米碳酸钙填充量为2.69%(体积分数)时,复合材料的拉伸强度、冲击强度和断裂伸长率分别提高了5.7%、11.3%和33.7%。改性后的纳米碳酸钙与PVC之间的界面作用与未改性碳酸钙相比有所减弱。扫描电镜照片(SEM)显示,添加了改性针形碳酸钙的聚氯乙烯断裂为韧性断裂,冲击断面呈现明显的拉丝现象。     

固相剪切碾磨制备聚丙烯/层状双金属氢氧化物纳米复合材料的力学性能及热稳定性

采用湿法固相剪切碾磨法(S<'3>M)制备了部分剥离型聚丙烯(PP)/层状双金属氢氧化物(LDHs)纳米复合材料,研究了PP/LDHs纳米复合材料的力学性能和热稳定性.结果表明,相对于聚丙烯,固相剪切碾磨制备的PP/LDHs纳米复合材料可在拉伸强度保持不变的情况下,明显提高其断裂伸长率和冲击强度.如当LDHs质量分数为...     

SiC-ZrO2(3Y)-Al2O3纳米复相陶瓷的力学性能和显微结构

本文介绍用非均相沉淀方法制备的纳米ＳｉＣ－ＺｒＯ２（３Ｙ）－Ａｌ２Ｏ３复合粉体经放电等离子超快速烧得到晶内型的纳米复相陶瓷,超快速烧结的升温速率为６００℃／ｍｉｎ,在烧结温度不保温,迅即在３ｍｉｎ内冷却至６００℃以下。     

丙烯酸树脂/TiO2有机-无机杂化材料的力学、热学和光学性能研究

采用溶胶-凝胶法成功制备了均匀透明的丙烯酸树脂/TiO2有机-无机杂化材料.通过动态力学分析仪(DMA)、电子拉力机(Instron Tester)、热失重分析仪(TGA)和紫外可见光谱(UV-VIS)等手段表征了杂化材料的力学、热学和光学性能.结果发现丙烯酸树脂与TiO2杂化后,聚合物的力学性能、热稳定性和紫外屏蔽性能均有显著提高.与原位聚合法相比,共混法合成该杂化材料可获得更优异的力学性能.增加丙烯酸树脂中的丙烯酸含量能显著降低相分离,从而使其各种性能,特别是力学性能得以提高.     

Achieving One‐Step Surface Coating of Highly Hydrophilic Poly(Carboxybetaine Methacrylate) Polymers on Hydrophobic and Hydrophilic Surfaces

It is highly desirable to develop a universal nonfouling coating via a simple one‐step dip‐coating method. Developing such a universal coating method for a hydrophilic polymer onto a variety of surfaces with hydrophobic and hydrophilic properties is very challenging. This work demonstrates a versatile and simple method to attach zwitterionic poly(carboxybetaine methacrylate) (PCB), one of the most hydrophilic polymers, onto both hydrophobic and hydrophilic surfaces to render them nonfouling. This is achieved by the coating of a catechol chain end carboxybetaine methacrylate polymer (DOPA‐PCB) assisted by dopamine. The coating process was carried out in water. Water miscible solvents such as methanol and tetrahydrofuran (THF) are added to the coatings if surface wettability is an issue, as for certain hydrophobic surfaces. This versatile coating method was applied to several types of surfaces such as polypropylene (PP), polydimethyl siloxane (PDMS), Teflon, polystyrene (PS), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC) and also on metal oxides such as silicon dioxide.     

Morphology and Mechanical Properties of PS/Al2O3 Nanocomposites Based on Selective Laser Sintering

1. IntroductionSelective laser sintering (SLS) is an advanced solidpowder freedom fabrication technology[1~4]. The ma-terials can be metals, ceramics, polymer or theirmixtures[5~10]. It can be adopted to prepare nano-composites to its best advantage for its process featureswith high density of the sintered specimens. It can beachieved by sintering layer by layer and high temper-ature grads engendered instantaneously by laser for itsown working mechanosm[11~15]. It is creative and im-portant …     

UP/GF/LCPU原位混杂复合材料的热性能和动态力学性能

利用自行合成的端基含有活性基团的热致性液晶聚合物(LCPU)对不饱和聚酯(UP)/玻璃纤维(GF)复合材料改性。用DSC、TGA、热膨胀仪、DMA测试了共混物的热性能和动态力学性能并研究其结构与性能的关系,用扫描电镜(SEM)对材料断面的形态结构进行了研究。结果表明:当LCPU含量为2.5%~5%,材料的综合热性能较好,材料的玻璃化转变温度、热失重温度、维卡软化点温度都有所提高,热膨胀性能得到改善。SEM观察表明,LCPU的加入对提高材料的断裂能具有一定的作用。     

尼龙66/SiO2纳米复合材料的界面结构及其对材料力学性能的影响

采用熔融共混的方法在双螺杆挤出机上制备出尼龙66/SiO2纳米复合材料,并利用红外光谱(FT-IR)、X射线光电子能谱(XPS)以及透射电子显微镜(TEM)对尼龙66/SiO2的界面进行了分析,结果发现,在熔融共混过程中经过表面改性的SiO2能够和尼龙66基体发生相互作用,形成一种基于共价键和氢键连接的界面层结构。力学性能测试结果表明这种界面结构的形成有利于纳米复合材料拉伸强度的提高。但对材料缺口冲击强度的影响并不明显。     

壳聚糖/聚(N-异丙基丙烯酰胺)全互穿网络水凝胶的制备及性能

以壳聚糖(CS)和N-异丙基丙烯酰胺(NIPAAm)为原料,N,N'-亚甲基双丙烯酰胺(BIS)为交联剂,制备具有温度和pH值双敏感性的全互穿网络水凝胶(Full-IPN);利用红外光谱(FT-IR)对其分子结构进行表征,扫描电镜(SEM)观察其内部形貌,并通过DSC对其低临界溶解温度(LCST)进行表征,最后研究了不...     

Inside Front Cover: Preparation of Porous Poly(dimethylsiloxane)‐Based Honeycomb Materials with Hierarchal Surface Features and Their Use as Soft‐Lithography Templates (Adv. Mater. 22/2006)

The inside cover shows a library of hierarchically patterned poly(dimethylsiloxane) surfaces, with a schematic view in the background. These materials are prepared by the ‘breath figure' technique, in work reported by Qiao and Connal on p. 3024, that utilizes a low glass transition temperature star polymer that can form ordered honeycomb materials and contour to nonflat TEM grids. These surfaces are also used as soft lithography masters to create the inverse pattern.     

Grafting Hypercrosslinked Polymers on TiO2 Surface for Anchoring Ultrafine Pd Nanoparticles: Dramatically Enhanced Efficiency and Selectivity toward Photocatalytic Reduction of CO2 to CH4

Metal deposition with photocatalyst is a promising way to surmount the restriction of fast e^?/h⁺ recombination to improve the photocatalytic performance. However, the improvement remains limited by the existing strategies adopted for depositing metal particles due to the serious aggregation and large unconnected area on photocatalyst surface. Here, a strategy is proposed by directly grafting hypercrosslinked polymers (HCPs) on TiO₂ surface to construct Pd-HCPs-TiO₂ composite with uniform dispersion of ultrafine Pd nanoparticles on HCPs surface. This composite with surface area of 373 m² g^?1 exhibits improved photocatalytic CO₂ conversion efficiency to CH₄ with an evolution rate of 237.4 µmol g^?1 h^?1 and selectivity of more than 99.9%. The enhancement can be ascribed to the grafted porous HCPs with high surface area and N heteroatom on TiO₂ surface for the stabilization of Pd nanoparticles, favoring the electron transfer and CO₂ adsorption for selective CH₄ production. This strategy may hold the promise for design and construction of porous organic polymer with semiconductor for efficient photocatalytic conversion.     

TiO_2对挤压铸造Al_2O_(3p)/钢基复合材料组织与力学性能的影响

在预制坯中加入TiO_2粉末,利用挤压铸造法制备Al_2O_3颗粒增强1065钢基复合材料,研究TiO_2对复合材料组织与力学性能的影响。结果表明:TiO_2使基体与Al_2O_3的结合界面形成了TiO_2、Al_2TiO_5界面层;添加TiO_2的复合材料硬度和三点弯曲强度分别为39.0HRC,743.94MPa,比未添加TiO_2的复合材料分别提高了10.0%,26.4%;断口扫描表明,添加TiO_2的复合材料界面结合良好无裂纹,Al_2O_3颗粒表现为穿晶断裂。说明加入的TiO_2改善了Al_2O_(3p)/钢基复合材料界面结合强度,提高了复合材料力学性能。