Modification of Mineral Powder by Various Organic Materials: Their Potential as Reinforcement for Unsaturated Polyester Composites

Russian Journal of Applied Chemistry - Industrial by product dumped from iron making industry (slag) has been modified by various chemical agents, particularly, paraffin wax, liquid nitrile...     

碳纤维自焊接骨架结构的形成及其复合材料性能研究

报道了一种将短切碳纤维(CF)自发焊接成三维网络结构的新方法.研究发现,尼龙6(PA6)与CF具有较强的相互作用,SEM照片及储能模量高温平台表明,添加少量PA6能够在PS基体中形成耐高温的CFPA6自焊接骨架结构,PA6用量越多,高温储能模量越高,自焊接骨架结构强度越大.研究证明,这种自焊接骨架结构能够大幅度提高PS/CF复合体系的热变形温度,碳纤维具有优异的导电导热性能,碳纤维骨架结构能够降低导电临界浓度,增强面内导热系数.进一步分析表明,PA6在碳纤维表面定向聚集是一个动力学过程,CF-PA6自焊接骨架强度与PA6黏附率NPA6呈线性关系;扩大PA6与PS的黏度差,延长热压时间均有利于提高NPA6,进而大幅提高网络结构强度.     

Bacterial Cellulose Nanopaper as Reinforcement for Polylactide Composites: Renewable Thermoplastic NanoPaPreg

Bacterial cellulose (BC) is often regarded as a prime candidate nano‐reinforcement for the production of renewable nanocomposites. However, the mechanical performance of most BC nanocomposites is often inferior compared with commercially available polylactide (PLLA). Here, the manufacturing concept of paper‐based laminates is used, i.e., “PaPreg,” to produce BC nanopaper reinforced PLLA, which has been called “nanoPaPreg” by the authors. It is demon­strated that high‐performance nanoPaPreg (v_f = 65 vol%) with a tensile modulus and strength of 6.9 ± 0.5 GPa and 125 ± 10 MPa, respectively, can be fabricated. It is also shown that the tensile properties of nanoPaPreg are predominantly governed by the mechanical performance of BC nanopaper instead of the individual BC nanofibers, due to difficulties impregnating the dense nanofibrous BC network.

     

胶原及明胶基天然高分子复合材料研究进展

胶原及其降解物—明胶是自然界中存在的一类丰富的绿色资源,来源广泛,具有可再生、可降解的"绿色"特性。将它们与其它物质复合形成新的复合材料,有着良好的性能和新的特性从而使其具有广阔的应用前景。日益严峻的环境问题,石油资源濒临匮乏,废旧材料的回收等问题使得人们更加寻求新的绿色的环境友好材料。本文根据天然资源各自的结构和性质,从复合方法和机理出发,综述了胶原及明胶与其它天然高分子(壳聚糖、淀粉、丝素蛋白、海藻酸钠)进行共混和复合以制备新的生物复合材料方面的研究进展。     

接枝改性木纤维对聚氯乙烯／木纤维复合材料力学性能的影响

接枝改性木纤维对聚氯乙烯／木纤维复合材料力学性能的影响廖兵，黄玉惠，赵树录，林果，丛广民（中国科学院广州化学研究所广州５１０６５０）关键词木纤维，聚氯乙烯／木纤维复合材料，接枝木纤维可作塑料的增强填料，但它与塑料的界面亲合性差，须进行改性，改善表面亲...     

Effect of the Coating of the Polymer Blend (Polyacrylamide/PEG 6000) on the Efficiency of Rice Husk as a Pesticide Carrier

In recent years the utilization of fibers and powders derived from agricultural sources has become a subject of interest. However, they have been exploited only from an engineering point of view, and the strong ability of agricultural wastes as a carrier for agrochemical formulations has been ignored. A study has been made on the possibility of using such an agrochemical waste, namely rice husk, which is readily available and biodegradable, as a carrier for pesticide formulation. The solid formulations were prepared by adsorbing deltamethrin on the rice husk. The deltamethrin‐adsorbed rice husk is then coated with the polymer blend of Polyacrylamide and PEG 6000 in varying ratios between the deltamethrin‐adsorbed rice husk and the polymer blend. The formulations were characterized by analytical methods such as FTIR and XRD techniques. Important physical properties from the formulation standpoint, such as solubility, dispersion stability, and wettability, were studied.     

Interlaminar Fracture Toughness of Carbon Fiber/Epoxy Composites using Short Kevlar Fiber and/or Nylon-6 Powder Reinforcement

Mode I (G_IC) and Mode II (G_IIC) interlaminar fracture toughness of carbon-fiber/epoxy composites have been investigated as a function of the amount of short Kevlar-29 fiber (SKF) and/or Nylon-6 powder (N6P) between continuous fiber layers. G_IIC increased with increasing crack length as a consequence of the presence of SKFs bridging in the wake of propagating crack. G_IIC of SKF alone could reach the maximum at an intermediate amount of SKF. G_IIC of SKF and N6P was lower than that of SKF alone because N6P prevented the orientation of SKF to out-of-plane. The extent of SKF's bridging phenomenon may be influenced by the amount and orientation of SKF. G_IC showed no significant effect with SKF and uniform irrespective of crack length. Scanning electron microscopy after G_IIC test showed that new surfaces were created by extensive fiber bridging, pull-out and fracture of SKF in random direction without any fixed pattern. © 1997 John Wiley & Sons, Ltd.     

Thermogravimetry as a Method for Investigating the Thermal Stability of Polymer Composites

Thermogravimetry was used to investigate the effects of different inorganic functional fillers on the heat resistance of polymer matrices. The kinetic parameters of thermal oxidative degradation were shown to depend on the polymer, the chemical composition of the filler surface, the filler concentration, and the processing method, which determines the distribution of filler particles in the polymer matrix. Magnetic fillers (carbonyl iron, and hexaferrites of different structural types) were shown to be chemically active fillers, increasing the heat resistance of siliconorganic polymers. Their stabilizing effect is due to blocking of the end silanol groups and macroradicals by the surface of the filler and non-chain inhibition of thermal oxidative degradation. In the case of fiber-forming polymers (UHMWPE, PVOH and PAN), most magnetic fillers are chemically inert, but at concentrations of 30–50 vol% they increase the heat resistance of the composite. Addition of carbon black increased the heat resistance of the thermoplastic matrix. The dependence of the thermal degradation onset temperature on the kaolin concentration in the polyolefin matrix exhibited a maximum. Analysis of the experimental results demonstrated the operating temperature ranges for different composites, and their maximum operating temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of Fiber Volume Fraction on the Flexural Properties of Unidirectional Carbon Fiber/Epoxy Composites

In this study, the effect of fiber content on the flexural property of continuous carbon fiber/epoxy composites was investigated. Samples with four different fiber volume fractions, 50, 60, 70, and 80 vol.%, were fabricated. For comparisons, cast epoxy resin was also prepared. It was observed that the flexural strength and modulus of this material are enhanced with increasing fiber volume fractions in the range of 50–70 vol.%. Results show that the carbon fiber/epoxy composites possess the largest fracture force and displacement when the fiber volume fraction is 70 vol.%, which is mainly attributed to the effective stress transfer of fibers. This can restrict crack tip propagation and blunt the crack tip, then consume abundant deformation energy and result in an increase of fracture work. On the other hand, poor flexural property was observed when the sample with high fiber volume fraction (80 vol.%) was tested. Three different types of failure modes were observed according to the fiber content.     

A Model for Evaluating and Determining the Most Appropriate Polymer Matrix Type for Natural Fiber Composites

The process of determining the proper polymer matrix type, using a wide range of criteria, to form a natural fiber–reinforced polymer composite is still not established enough. This work introduces, for the first time, a model to select the proper polymer matrix type for natural fibers to enhance the sustainability of the automotive industry. The model was developed to rank different polymers and to determine their relative merits considering 20 different criteria simultaneously, including different physical, mechanical, chemical, environmental, and technical criteria. This work can support establishing a road map for proper selection of polymers in different engineering applications as well as increasing the reliability of the polymer selection process.     

Exploring the Potential of Metallodrugs as Chemotherapeutics for Triple Negative Breast Cancer

This review focuses on studies of coordination and organometallic compounds as potential chemotherapeutics against triple negative breast cancer (TNBC) which has one of the poorest prognoses and worst survival rates from all breast cancer types. At present, chemotherapy is still the standard of care for TNBC since only one type of targeted therapy has been recently developed. References for metal-based compounds studied in TNBC cell lines will be listed, and those of metal-specific reviews, but a detailed overview will also be provided on compounds studied in vivo (mostly in mice models) and those compounds for which some preliminary mechanistic data was obtained (in TNBC cell lines and tumors) and/or for which bioactive ligands have been used. The main goal of this review is to highlight the most promising metal-based compounds with potential as chemotherapeutic agents in TNBC.     

耐热性高聚物基自润滑复合材料的研究进展

综述了聚四氟乙烯、聚醚醚酮、聚苯硫醚、聚酰亚胺等几类耐热性高聚物基自润滑复合材料的近期发展概况,并提出了今后研究高聚物基自润滑复合材料值得注意的几个问题。     

半晶聚合物复合材料中的横晶

半晶聚合物复合材料,尤其是纤维增强的半晶聚合物复合材料,在其界面区常有横晶结构生成。本文综述了横晶自发现至今的研究情况,对横晶的形成和生长机理进行了描述,对影响横晶生成和性质的因素进行了分析,着重介绍了几种典型半晶聚合物复合材料体系的横晶形态,并讨论了横晶对界面特性和复合材料性能的影响。     

Reversible Amidation Chemistry Enables Closed-Loop Chemical Recycling of Carbon Fiber Reinforced Polymer Composites to Monomers and Fibers

Highly efficient recycling of carbon fiber reinforced polymer composites into monomers and fibers is a formidable challenge. Herein, we present a closed-loop recycling approach for carbon fiber reinforced polymer composites using reversible amidation chemistry, which enables the complete recovery of intact carbon fibers and pure monomers. The polymer network, synthesized by amidation between a macromonomer linear polyethyleneimine and a bifunctional maleic anhydride cross-linker, serves as a matrix for the construction of composites with exceptional mechanical properties, thermal stability and solvent resistance. The matrices can be fully depolymerized under the acidic condition at ambient temperature, allowing the effective separation and recovery of both carbon fibers and the two monomers. The reclaimed carbon fibers retain nearly identical mechanical properties to pristine ones, while pure monomers are recycled with high separation yields (>93 %). They can be reused in for multiple cycles for the manufacture of new composites, whose mechanical properties recover over 95 % of their original properties. This line of research presents a promising approach for the design of high-performance and sustainable thermoset composites, offering significant environmental and economic benefits.     

On the Mechanism of Aggregate Formation in Metal-Filled Polymer Composites

Mechanisms of the aggregation of nickel particles in a curing polymer matrix are studied. It is shown that the Brownian diffusion of particles and their orthokinetic coagulation cannot explain the experimental data on the aggregate formation obtained earlier.     

高压下聚合物及其复合体系的结构与性能研究进展

随着科学技术的进步,材料科学有了很大的发展,其中高分子材料的发展应用尤为迅速。许多高分子材料在新的环境下结构与性能之间的关系都有待于研究。因此,了解它们在一些极端条件下（如高温高压、低温低压等）,结构与性能之间的变化规律是十分必要的。高压对聚合物材料的结构与性能有较大的影响。国内外学者主要对聚烯烃、聚酯、聚酰胺等聚合物及其复合体系的高压结晶和高压退火行为进行了一系列研究工作。本文介绍了这一领域的研究概况和最新进展。