水溶性PVA薄膜的制备及其改性研究进展

综述了近年来水溶性聚乙烯醇(PVA)薄膜的制备工艺进展,介绍了其在共聚改性、共混改性、复合改性方面的研究进展,以及在制备工艺、改性方法上的优缺点。共混改性可简单通过材料混合显著提高性能;与共混改性相比,共聚改性的组分混合较为均匀,但是条件较难控制;复合改性可以综合共聚改性和共混改性的优点。     

聚酰亚胺树脂改性研究进展

总结了近年来聚酰亚胺树脂(PI)的改性研究进展。重点介绍了PI的结构与功能改性、共聚改性、共混改性(共混树脂包括环氧树脂、热塑性聚氨酯和聚四氟乙烯等)和填充改性(填料包括无机填料、杂化填料、金属和金属氧化物)等方面的研究内容,并对PI未来的研究方向进行了展望。     

聚酰亚胺/无机粒子复合材料的制备及其性能研究进展

综述了聚酰亚胺(PI)与无机粒子复合的研究进展,着重介绍了复合材料的溶胶-凝胶法、插层复合法、机械共混法三种制备方法。将PI与无机材料复合可得到集有机材料和无机材料优异性能于一体的复合材料,改善了传统PI存在的不足。无机粒子改性后的PI在不明显降低材料的热性能和力学性能的同时富集了无机小分子高模量、耐氧化、耐摩擦等性能,优化了材料的性能。引入无机纳米粒子,材料的内部分子堆积、相互作用等发生改变,对气体的选择透过性有很大的改善。改性后的PI具有可控的介电性能、膨胀性能等。     

共聚共混改性聚酰亚胺的摩擦磨损性能研究

为了改善传统均苯四甲酸酐(PMDA)–4,4′-二胺基二苯醚(ODA)型聚酰亚胺(PI)的摩擦性能,分别以共聚和共混两种方式,引入柔性二胺单体芳香杂环二胺(DAMI),从分子结构制备不同ODA/DAMI物质的量之比的共聚和共混改性PI。并用摩擦磨损试验机、扫描电子显微镜、万能试验机以及X射线衍射仪等分析共聚和共混改性PI的结构和性能。结果表明,当ODA/DAMI物质的量之比分别为3∶1和5∶1时,共聚和共混改性PI具有最优的综合摩擦磨损性能,摩擦系数分别为0.273和0.280,磨损率分别为9.28×10–14,11.2×10–14 m3/(N·m)。共聚改性PI的摩擦系数随摩擦时间的增加变化比较稳定,其在兼顾磨损率和摩擦系数方面比共混改性PI更具优势。共聚和共混法改性PI磨损机理相似,主要为粘着磨损、磨粒磨损和疲劳磨损。随DAMI含量增加,两种改性PI的拉伸强度、拉伸弹性模量和玻璃化转变温度均呈下降趋势,当DAMI含量较高时,两种改性PI结晶取向增加,磨损率急剧升高。     

聚酰亚胺/钛酸钡复合薄膜的制备及性能

将钛酸钡(BT)粒子与聚酰胺酸溶液共混,亚胺化后得到聚酰亚胺(PI)包覆的BT(PI@BT)粒子.分别以BT粒子和PI@BT粒子为改性填料,通过原位聚合法制备了PI/BT和PI/PI@BT复合薄膜,对比了两种复合薄膜的结构与性能.结果表明:PI@BT粒子具有明显的核壳结构,较BT在PI基体中分散更均匀,从而有效地提高了...     

聚酰亚胺合成及改性的研究进展

主要介绍了聚酰亚胺(PI)的合成方法,包括通过在聚合过程中或在大分子反应中形成酰亚胺环,或通过已含有酰亚胺环的单体聚合成PI.阐述了改性PI的几种方法,包括结构改进、共混改性、共聚改性和填充改性.针对PI合成工艺和改性中存在的问题,提出了发展前景.     

聚丙烯增韧改性的方法及机理

结合近年来的研究成果,对无规共聚改性、嵌段共聚改性、接枝共聚改性、改变立体结构、橡-塑共混改性、塑-塑共混改性、纤维填料改性、无机粒子改性、β晶型成核剂改性、纳米复合改性、多组分复合改性等多种聚丙烯的增韧方法及其机理进行了综述;指出橡-塑共混改性依然是目前最有效的增韧方法,多组分复合增韧是今后的发展方向。     

丙烯酸酯改性水性聚氨酯的研究进展

介绍了聚氨酯/丙烯酸酯(PUA)复合乳液的制备方法,包括物理共混、交联共混、复合乳液共聚、核/壳结构乳液共聚法及互穿聚合物网络(IPN)法等,同时从无机纳米粒子改性、氟改性、有机硅改性和环氧树脂(EP)改性等方面对改性PUA复合乳液的研究进展进行了概述。     

芳香性聚酰亚胺的阻燃改性研究进展

综述了芳香性聚酰亚胺(PI)在共混、共缩聚以及结构改性方面的研究进展,其中共聚改性按引入基团的不同又分为聚酰胺酰亚胺(PAI)、聚酯酰亚胺共聚物、引入含氮杂环等,结构改性包括在主链中引入杂元素、功能性侧基的引入、引入扭曲或非共平面结构,并提出PI在阻燃领域的发展方向。     

超高分子质量聚乙烯纤维及其复合材料的共混改性

超高分子质量聚乙烯(UHMWPE)纤维是一种重要的战略材料，目前已经广泛应用于防弹背心、安全纺织品、船用绳索和高强度复合材料等领域；但其也存在易蠕变、耐热性差以及再加工、复合困难等问题，亟需高效改性以进一步拓展应用。聚焦近年来UHMWPE的共混改性研究，综述了共混改性对UHMWPE纤维力学、耐热、加工等性能的影响，探讨了共混改性的作用机制，展望了共混改性UHMWPE纤维及其复合材料的应用领域及前景。     

Long fiber reinforcement of polypropylene/polystyrene blends

The recycling of inseparable polymer mixtures usually results in blends with poor mechanical properties. A mixture of PP and PS was taken as a model compound for a recyclate. The effect of adding glass fibers to a mixture of PP/PS (70/30) was studied, with special attention to long glass fiber reinforcement. Test specimens were made in three different ways: by dry blending (direct injection molding), mild compounding with a single screw extruder, and compounding with a twin screw extruder. The fiber concentration was varied from 0 to 30 wt%. The fiber lengths were determined to investigate fiber attrition. The fiber lengths in the samples were 1.09 mm for dry blending, 0.72 mm for single screw compounding, and 0.33 mm for twin screw compounding. The mechanical behavior was studied by unnotched and notched Izod impact and tensile tests. The PP/PS blend had a low fracture strain and low unnotched Izod impact strength compared with a PP homopolymer. With an increasing fiber concentration and fiber length, the modulus, tensile strength, and particularly the impact strength increased. With a 30 wt% glass fiber of the long fiber compound (dry blended), the modulus was raised by a factor of 3.5, the fracture stress by a factor of 2.5 and the unnotched Izod impact strength by a factor of 10. The product quality as judged by the scatter of the data was best for the twin screw compound and poorest for the dry blend. Compounding with a single screw extruder gave fairly constant injection molding product properties, combined with excellent mechanical properties.     

聚丙烯共混发泡材料研究进展

综述了聚丙烯(PP)发泡材料的特点及常用发泡方法,重点介绍了PP与无机矿物粉体、聚乙烯、橡胶、玻璃纤维、木纤维等共混制备发泡材料的研究进展,指出了PP发泡材料的发展方向。     

Comparative Characterization of PP Nano‐ and Microcomposites by In‐Mold Shrinkage Measurements and Structural Characteristics

Poly(propylene)‐clay nanocomposites and poly(propylene) containing conventional inorganic fillers such as calcium carbonate (CaCO₃) and glass fiber were used in a comparative study focusing on dimensional stability, structure, mechanical and thermal properties. Micro‐ and nanocomposites were prepared by melt blending in a twin‐screw extruder. The relative influence of each filler was observed from dimensional stability measurements and structural analysis by WAXD, TEM, and thermal and mechanical properties. At equal filler loadings, PP/clay nanocomposites exhibit an improvement in dimensional stability and were the only composites capable of reduced shrinkage in both in‐flow and cross‐flow directions. The flexural modulus of PP increased nearly 20% by compounding with 4% organoclay, as compared to a similar performance obtained by compounding with 10 wt.‐% of CaCO₃ or approximately 6 wt.‐% of glass fiber. The HDT and thermal stability of PP were enhanced by using nanoclay as filler.

     

Impact of processing method and surface functionality on carbon nanofiber dispersion in polyimide matrix and resulting mechanical properties

Composites were produced with functionalized carbon nanofibers (CNF) and polyimide (PI) matrix using either in situ polymerization or blending processes. The impact of the composite processing method, CNF surface chemistry, and fiber loadings on the dispersion of fibers and mechanical properties of composites were investigated. Specifically, functionalization of oxidized CNF with a diamine and polyimide oligomer that mimicked the structure of the base polyimide led to improved dispersion of CNF in the matrix polymer. Samples produced using precipitation blending from hot solvent and in situ polymerization exhibited improved dispersion and reduced agglomeration of CNF relative to samples made using direct blending. While SEM images showed poorly dispersed pristine CNF in PI in the form of agglomerations and thick deposition layer on the bottom of composite film, there was clearly better dispersion for functionalized CNFs. Composites produced with functionalized CNF exhibited improvements in modulus, glass transition temperature and tensile strength relative to the base polyimide. POLYM. COMPOS. 35:1473–1485, 2014. © 2013 Society of Plastics Engineers     

Correlation between processing conditions and fiber breakage during compounding of glass fiber‐reinforced polyamide

The inter‐relationship between processing conditions and fiber breakage has been studied for glass fiber‐reinforcedpolyamide 12, prepared using (i) an internal batch mixer, (ii) a laboratory scale corotating twin screw extruder, and (iii) an industrial scale twin screw extruder. The average fiber lengths and fiber length distributions were measured for various compounding conditions (screw or rotor speed, mixing time, feed rate). Experimental results have shown that fiber breakage depends on both screw speed and mixing time, the later being controlled, in an extruder, by the feed rate. For a given compounding system (batch mixer or twin screw extruder), the energy input (specific mechanical energy, SME) during the compounding process is found to be a reliable parameter, which governs fiber length (average, minimal, and maximal) evolution. Experimental data are correctly described with a model defining change in fiber length as a function of SME. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Twin screw reinforced plastics compounding

Co-rotating, self-wiping twin-screw equipment has been developed which incorporates fiber glass or fillers into various plastics to form compounds with superior mechanical properties. Fiber glass bundles are folded into the plastic melt in such a fashion that each glass strand is wetted out with minimum breakage of the strand. The intensity of compounding is controlled externally to condition the basic polymer for optimum filler incorporation. The external control permits compounding a wide variety of plastics over a range of throughputs. The degree of mixing can be varied while the machine is in operation. The fiber resin blend passes through an independently controlled extruder for pelletizing with a hot die face cutter. Either air or water quench systems can be used for cooling the pellets. The gentle handling of the fiber resin blend through compounding and extrusion not only minimizes glass breakage, but also minimizes wear on the equipment. Retention of glass fiber length and good strand bonding impart superior properties to the fiber resin product.     

纤维填充PTFE复合材料的摩擦学研究

在聚四氟乙烯（PTFE）中分别填充碳纤维（CF）、玻璃纤维（GF）及这两种纤维不同配比的混杂纤维（HF），制备了具有不同力学性能和摩擦磨损性能的PTFE基复合材料。探讨了填料组成对复合材料硬度和干摩擦条件下摩擦磨损性能的影响，并研究了PTFE基复合材料磨损表面的形貌学。结果表明，适量填充CF和GF均可提高PTFE的摩擦磨损性能，CF比GF效果更为显著；CF和GF的混杂纤维填充PTFE复合材料．表现出一定的协同性，比填充单种纤维，其效果更显著。     

Effect of surface treatment of carbon fiber on the electrical and mechanical properties of high-impact polystyrene composite

Carbon fiber (CF), PU(polyurethane)-coated carbon fiber (CF-PU) and Ni-coated fiber (NCF) treated with a coupling agent (CA) were used to prepare composites for high impact polystyrene (HIPS) by melt blending. The optimum concentration of the titanate CA is 1.5 phf (per hundred parts of filler) when coupled with the carbon fibers. A composite prepared by adding a CA directly into the matrix which was then reinforced with fibers was investigated for comparison. These composites were evaluated for electromagnetic interference shielding effectiveness, dispersion, and adhesion between the polymer and the filler by means of scanning electron microscopy (SEM). The addition of CA generally improved the shielding effectiveness; this is especially apparent when the matrix was pretreated with CA before compounding with the fibers. The tensile properties were also improved upon CA addition.     

硅烷偶联剂在聚合物基复合材料增容改性中的应用

综述硅烷偶联剂在聚合物复合材料中的增容机理及使用方法，硅烷偶联剂在玻璃纤维增强复合材料，无机粒子填充复合材料，聚合物共混改性及新型聚合物基复合材料中的应用，为硅烷偶联剂的深入研究及拓展应用提供参考依据。