The production of glass fiber-reinforced poly(butylene terephthalate) on a continuous kneader

In poly(butylene terephthalate) based compositions, thermal degradation of the polymer matrix during processing has to be minimized to achieve quality products. Experience has shown a temperature-residence time relationship, indicating that for mixing systems with high product temperatures, the residence time of the product has to be reduced to avoid excessive thermal degradation. The power density of the mixing system is related to the specific energy input and the residence time of the product. From rheology, the power density is also known for a simple shear deformation which can thus be used to characterize the shear intensity of a particular mixing process. Comparing two different mixing systems by their power density provides us with a qualitative better understanding why higher shear is permitted with lower residence time. From theoretical considerations it was found that for a temperature-sensitive product, like PBT, the power density in the mixing operation can be further raised, taking into account that with shorter residence time a higher product temperature is permitted. Production-scale test work was carried out on a 200 mm screw-diameter continuous kneader to investigate the effect of running conditions and screw design on the thermal degradation of two different types of PBT. Results have shown that for the high-viscosity PBT a linear relationship exists between product temperature and the viscosity retained upon compounding. In a two-stage kneader only minor thermal degradation is encountered in the melting section, but conditions become critical in the mixing stage due to the viscosity increase after introducing the glass fibers to the melt. A new feature in compounding thermodegradable products is the addition of unmolten polymer into the mixing stage of the kneader since this leads to a reduction in the product end temperature and, consequently, thermal degradation of the matrix material. The limited results obtained so far indicate that an optimum exists as to the amount of pellets added. At a 15 percent level the product temperature was reduced by 20°C as compared to 10°C at 20 percent. An energy balance carried out on the continuous kneader indicates that because of the low melt viscosity approximately 30 percent of the energy put into the product in the melting section of the kneader originates from external heating. A rough comparison shows that the power density of a continuous kneader is twice that of a single-screw extruder designed for compounding PBT, but, can be tolerated because of the considerably lower residence time in the former mixing system.     

FRTP材料在土木工程制品中的应用研究

FRP材料根据树脂材料的不同分为FRTP（热塑性FRP）和FRSP（热固性FRP）两种；根据FRTP材料自身的物理力学特点，对FRTP材料浸渍与成型工艺、FRTP材料与FRSP材料的物理力学性能比较、土木工程用FRTP筋／板等制品及其物理力学性能及其在土木工程中的国内外应用现状进行了研究；指出了需要进一步研究解决的一些问题。     

不同混合设备对聚苯醚/尼龙66合金性能的影响

通过力学性能测试和扫描电子显微镜分析,研究了啮合同向双螺杆挤出机、啮合异向双螺杆挤出机和往复式单螺杆销钉挤出机(Buss机)3种连续共混设备对聚苯醚/聚酰胺66（PPO/PA66）合金性能的影响。结果表明,作为传统共混改性设备,啮合同向双螺杆挤出机适于PPO/PA66合金的制备;啮合异向双螺杆挤出机对于PPO/PA66合金的制备也具有一定的可开发性;Buss机不利于PPO/PA66合金的制备。     

Effects of fiber length and orientation distribution on the elastic modulus of short fiber reinforced thermoplastics

A method including the effects of fiber length and orientation distribution to predict elastic moduli of short fiber reinforced thermplastics (FRTP) is presented. The fiber length distribution in FRTP has an asymmetric character with a tail at the long fiber end. Statistical distribution functions such as Weibull or log-normal can be used to represent this kind of distribution. Orientation distribution of fibers in FRTP can be characterized by a single parameter exponential function, $F(\theta) = \frac{{1 - \lambda \theta }}{{1 - e^{ - \frac{\P}{2}\lambda } }}$. A large λ indicates a highly oriented material whereas small λ represents a quasi-isotropic material. As fiber length and orientation distribution functions have been characterized, the elastic moduli of FRTP can be predicted. First, the mean elastic moduli of unidirectional plies are predicted through the fiber length distribution. Then the stacking sequence of laminate is assumed to be as the fiber orientation distribution of FRTP, and the overall elastic moduli of FRTP are estimated based on the laminate-plate method.     

连续纤维增强热塑性塑料开发动向分析

分析了国内外纤维增强热塑性塑料（ FRTP）的发展趋势，指出连续纤维增强热塑性塑料能最大限度发挥材料性能；对比了现行工艺技术的优劣、国内外发展现状，有助于对我国纤维增强热塑性塑料的发展有方向性的判断。     

国外纤维增强热塑性塑料发展概况

纤维增强热塑性塑料（FRTP）因其重量轻,抗冲击性和疲劳韧性好,成型周期短,可循环利用等诸多优点,近年在稳定发展。本文概述了国外纤维增强热塑性塑料的发展形势、材料种类、知名厂商及其产品和FRTP最终制品的成型工艺。     

国外纤维增强热塑性塑料发展概况(Ⅰ)

纤维增强热塑性塑料(FRTP)因其重量轻,抗冲击性和疲劳韧性好,成型周期短,可循环利用等诸多优点,近年在稳定发展,已进入汽车、轨道交通、运输、航空航天、能源、基础设施、建筑、电子、防卫、船艇、工业、医疗、体育娱乐等多种应用市场。有关厂商为之研发了各种形式的FRTP材料、产品和FRTP最终制品的成型工艺。     

Compressive Creep of Basalt Fibers and Epoxy Resin Linear Composite

Abstract

Basalt fibers similarly as a glass fibers are used for production of high, temperature resistant and chemically inactive products. Basalt is used mainly for molded products (flag stones, pipes) with increased abrasion resistance, temperature resistance and chemical resistance or in a form of short fibers for insulation purposes (basalt wool).

Application of the technology of continuous spinning leads to the sufficiently even basalt filament yarns applicable in the textile branch. In this contribution the thermal expansion and compressive creep of basalt and composite with epoxy resin are investigated.     

国外纤维增强热塑性塑料发展概况(Ⅱ)

纤维增强热塑性塑料(FRTP)因其重量轻,抗冲击性和疲劳韧性好,成型周期短,可循环利用等诸多优点,近年在稳定发展,已进入汽车、轨道交通、运输、航空航天、能源、基础设施、建筑、电子、防卫、船艇、工业、医疗、体育娱乐等多种应用市场。有关厂商为之研发了各种形式的FRTP材料、产品和FRTP最终制品的成型工艺。     

Composite reinforcement: Recent development of continuous glass fibers

Light weight, glass fiber-reinforced composites have gained a broad, global acceptance in commercial markets with a total of more than 7 billion of US dollars in revenue since its first commercial production in US in mid 1930s. This article briefly reviews recent development of continuous glass fibers with a focus on high-performance glass fibers. With accelerated commercial demands on high-performance glasses and/or glass fibers, there is a growing realization of fundamental needs in decoding nature of glass structures or “genes” of glass structure building blocks and establishing their relationships to properties of glasses or glass fibers. The related database development can enable researchers shortening the number of product development cycles to bring new fiber products to the market. A special section is, therefore, provided illustrating recent progress in characterizations of glass structures by using techniques of nuclear magnetic resonance spectroscopy, Raman spectroscopy, and molecular dynamics simulations.     

复合材料用高性能纤维及热塑性树脂发展现状

介绍了芳纶、碳纤维和超高相对分子质量聚乙烯等3种纤维的基本性能、国内外生产及应用情况,还介绍了聚酰胺、聚醚醚酮、聚苯硫醚及聚酰亚胺等4种热塑性树脂的性能及在研发和生产方面与国外的差距,由此提出了加强研究机构与企业充分合作、国产材料应用及原材料质量控制的建议,并对今后热塑性复合材料的发展进行了展望。     

Polymere hochleistungs-faserverbundwerkstoffe

Advanced polymer-matrix composites are defined as materials consisting of continuous high strength, high modulus fibers, aligned and embedded in a polymeric matrix. Due to their low density they exhibit specific mechanical properties (i.e., strength/density and stiffness/density) that considerably exceed those of high strength metals, which demonstrates their great potential for lightweight structural components. The primary reinforcement materials are various types of carbon fibers, aramid fibers and glass fibers. While these are commonly combined with epoxy resins, many new matrix systems with distinct property profiles, including heat resistant thermoplastics, have been developed recently. This paper presents an overview of this rapidly developing field covering principles of composite-property improvement, synthesis and processing of the constituent materials, and processing and manufacturing techniques to combine fibers and matrix to produce a composite laminate or part. Several mechanical composite properties critical for structural design and performance are discussed in terms of the contribution of and interaction between the fiber and matrix constituent.     

Mechanical properties of short fiber reinforced thermoplastic composites —I. Elastic properties and predictions

Twin roll-mill and compression molding machines were used to process the unidirectional ply of short fiber reinforced thermoplastics (FRTP). FRTP laminates were prepared by compression molding of angle plies with the desired stacking sequences.The fiber length and orientation distributions in FRTP took place after processing. Therefore, a statistical distribution function such as WeiBull distribution function was applied to represent the existing fiber length distribution. The orientation distribution in FRTP was characterized by a single parameter exponential function. Elastic moduli of the unidirectional ply were predicted by the Halpin-Tsai equation where the fiber length distribution was introduced to the estimation. The overall elastic moduli of laminates were estimated based on the simulated laminate-plate method. A comparison of measured elastic moduli with theoretical predicted results from unidirectional ply and laminate was discussed in this study.     

碳纤维增强热塑性复合材料工艺与性能的研究

短切碳纤维的ＢＵＳＳ捏合机和连续碳纤维的双螺杆挤出增强工艺开发了碳纤维增强聚酰胺,碳纤维增强聚甲醛,等碳纤维增强热塑性工程塑料,并以碳纤维增强聚酰胺为例进行成型工艺的研究,探讨了加 工工艺参数与材料性能的关系。     

Pultrusion of epoxy matrix composites: Pulling force model and thermal stress analysis

Pultrusion processing for epoxy resin with glass, carbon, and DuPont Kevlar fibers has been modeled. The model has three submodels: heat transfer, pressure, and force. The validity of the model was verified by comparison of results obtained on the glass fiber/epoxy system with experimental values in the literature. The application of the model permitted an explanation of the difference in behavior between polyester and epoxy resins. Different process variables were studied. Increasing the pulling velocities increases force values. The influence of the fiber content was analyzed. Different wall temperature profiles were used and the residual thermal stresses were calculated. The use of different fibers (glass, carbon, and Kevlar) was simulated under the same process conditions. The higher pulling force was obtained for composites with carbon fibers.     

Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen Impurities

Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl₄) to the glass. During melting, the chlorine from TeCl₄ reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m).     

A comparative study of fiber breakage in compounding glass fiber-reinforced thermoplastics in a buss kneader,modular Co-rotating and counter-rotating twin screw extruders

The breakage of glass fibers was measured for several different types of continuous mixers including (i) Buss Kneader, (ii) modular intermeshing co-rotating twin screw extruder, and (iii) modular intermeshing counter-rotating twin screw extruder. Comparisons are made using different screw configurations, loadings, feeding ports, and mixing elements. Downstream feeding of glass fibers and milder screw configuration favor less breakage of glass fibers.     

Linear viscoelastic and morphological description of multiphase systems affected by processing parameters

Influence of processing methods, in terms of comparing compression and injection moldings, on the rheological behavior of polycarbonate (PC)/acrylonitrile‐butadiene‐styrene (ABS) blends and PC/ABS/glass fibers composites is presented. Blend compositions and fiber content are considered as material variables. For blends, the effect of the processing route on the viscoelastic functions is evident only for low shearing frequencies. Injection molding created morphology with cocontinuous character, while compression molded blends have “relaxed” structure, where dispersed phase domains are several times larger than in injection molded ones. The glass fiber reinforcement led to the significant differences in viscoelastic properties of composites processed by injection and compression molding. Injected composites have both moduli always higher than compression molded. Also, fiber lengths are reduced more for compressing molding. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Progress Report on Natural Fiber Reinforced Composites

This century has witnessed remarkable achievements in green technology in material science through the development of natural fiber reinforced composites. The development of high‐performance engineering products made from natural resources is increasing worldwide day by day. There is increasing interest in materials demonstrating efficient use of renewable resources. Nowadays, more than ever, companies are faced with opportunities and choices in material innovations. Due to the challenges of petroleum‐based products and the need to find renewable solutions, more and more companies are looking at natural fiber composite materials. The primary driving forces for new bio‐composite materials are the cost of natural fibers (currently priced at one‐third of the cost of glass fiber or less), weight reduction (these fibers are half the weight of glass fiber), recycling (natural fiber composites are easier to recycle) and the desire for green products. This Review provides an overview of natural fiber reinfocred composites focusing on natural fiber types and sources, processing methods, modification of fibers, matrices (petrochemical and renewable), and their mechanical performance. It also focuses on future research, recent developments and applications and concludes with key issues that need to be resolved. This article critically summarizes the essential findings of the mostly readily utilized reinforced natural fibers in polymeric composite materials and their performance from 2000 to 2013.     

玻璃纤维的形态对氯氧镁水泥增韧效果的影响

本文对短切、连续布置的玻璃纤维对氯氧镁水泥抗弯强度、抗冲击强度、韧性指数的影响进行了研究.结果表明:短切纤维增强氯氧镁水泥基体的增韧效果比连续纤维更好.