高聚物精密挤出的研究

高聚物的挤出成型是一个十分复杂的生产过程[1] 。在此过程中 ,高聚物要经历固体输送、熔融、混合、增压、泵送、成型、冷却固化等过程 ,并受到剪切、拉伸、压缩以及加热、冷却等作用 ,发生熔融、固化、取向、解取向、结晶等复杂的相态和结构变化 ,使得挤出过程的控制难度较大 ,导致制品成型的精度较低。这不仅浪费了大量的树脂材料 ,也限制了高聚物挤出制品的应用范围。为了提高挤出过程的稳定性、均匀性和可靠性 ,科研工作者从挤出过程机理模型、挤出机优化设计、成型工艺条件控制、成型辅机控制等方面做了大量的基础理论研究工作 ,并研制…     

Permeability barriers by controlled morphology of polymer blends

Melt fabricated plastic articles with improved solvent and vapor barrier properties are of great need in the packaging industry. Various techniques, such as coextrusion, surface treatments, and coatings, are being employed currently towards this objective. Present work has identified a unique polymer blend approach to impart solvent and gas barrier properties to a polyolefin material. This involves incorporation of small amounts of a modified nylon barrier material, and processing under controlled conditions, in single step blowmolding or other extrusion processes. The unusual barrier effects obtained at small concentrations of the barrier material are obtained by the controlled morphology of the dispersed phase and optimum formulation of the ingredients.     

机电工业的快速发展为橡塑密封件行业带来新商机

橡塑密封件属于机械基础件,密封件在动力机械行业占有重要的地位,是机械产品性能、质量、可靠性、耐久性的重要保证。密封件市场面临大发展的新时期,介绍了橡塑密封产品的潜在市场及需求商机,同时指出了加快橡塑密封件产品发展的对策及橡塑密封件行业的发展趋势。     

Some properties of materials based on self-bound silicon carbide and the possibilities of their use

Results of an investigation of some properties of self-bound silicon carbide are presented. Linear dependences of the ultimate bending strength and Young's modulus on the density of the material are presented. The highest properties were observed in a material with a density of 3100 kg/m³. Results of tests of articles of self-bound silicon carbide used as seals for various pumps for aggressive and abrasive-containing media are considered. Problems of organization of commercial production of articles of self-bound silicon carbide and a feasibility study of such an enterprise are presented. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 7, pp. 11 – 14, July, 1996.     

内,外环半包覆氟塑料“O”形圈的研制

主要介绍内、外环半包覆四氟膜“O”形圈的研制，该技术已用于无油润滑密封和液压、气动往复密封。可降低摩擦系数，提高密封的可靠性和使用寿命。     

专用橡胶制品制造工艺的改进

为了提高中空圆筒型橡胶制品的质量和合格率，采用了橡胶挤出机挤出工艺，研究了配方中填料和工艺方法对挤出质量的影响，并进行了多批次的生产，试验结果表明，调整橡胶配方，选择合适的石棉填料，控制胶料用量，挤出温度，挤出速度，冷却方式等技术手段，可以提高挤出质量，生产状况表明，挤出工艺是制造中空圆筒形橡胶制品的有效手段，可以大大提高中空管状产品的质量和合格率。     

ABS的3D打印制品表面质量研究

采用熔融沉积成型(FDM)三维(3D)打印技术成形丁二烯-丙烯腈-苯乙烯共聚物(ABS)制件,探究喷嘴挤出温度及层高变化对制件表面质量的影响.针对不同的挤出温度、层高等打印工艺参数,制备形状、尺寸一致的多组制件,使用形状测量激光显微镜对制件的表面形貌数据进行了采集并对分析,得出了算术平均高度(Sa)、最大高度(Sz)、...     

Glass-to-metal seals for solid oxide cells at the Politecnico di Torino,an overview

A summary and update of the research on the design, process, and testing of glass and glass-ceramic to metal seals for solid oxide cells (SOC) conducted during the last 13 years at the Politecnico di Torino, Italy, within our research group and with several international collaborations, is presented and discussed. Glass and glass-ceramic-based materials play a key role in SOC performance and durability as well as in the sealing and joining of metallic interconnects. The sinter-crystallization method is a powerful technique that is used to obtain dense and reliable glass-ceramics capable of providing hermetic joining and seals. The issues, learned from our experience, that have an impact on the lifetime behavior of glass and glass-ceramic to metal seals are briefly reviewed in terms of challenges and working conditions. The mechanical characterization of glass-to-metal seal materials has a crucial impact on the overall performance, as the metal–glass interface plays a key role on the final joining strength and reliability. Several glass compositions are presented along with results on their characterization and behavior as joining materials for metallic interconnects, with a focus on their potential use as SOC seals.     

阻燃聚甲醛的研究

通过阻燃剂的筛选实验，正交实验和配方实验研制了阻燃聚甲醛（POM），并研究了阻燃POM的成型加工工艺。结果表明，最适于POM的阻燃剂为三聚氰胺，聚磷酸铵（APP）和季戊四醇双磷酸酯三聚氰铵盐（MPP）；将这三种阻燃剂复配使用，其效果比单独使用好，具有协同作用，在100份POM中加入40份APP和MPP的混合物及20份三聚氰胺，可使阻燃POM的氧指数达到49％；在100份POM中加入30份APP和MPP的混合物，20份三聚氰胺及10份吸醛剂A，可使阻燃POM的氧指数达到50％，垂直燃烧达FV－0级，两者的力学性能下降率小于50％＜阻燃POM挤出造粒时宜采用渐变式螺杆挤出机；注塑时宜采用螺杆式注塑机，挤出和注射成型的工艺条件与普通POM相同。     

非接触式气体端面密封的动力学分析方法概述

本文综述了国内外主要的非接触式气体端面密封动力学分析方法,分线性化和非线性化两个部分介绍了常用的研究方法及其基本步骤,并比较了几种方法的优缺点。     

低发泡RPVC挤出成型的配方和工艺研究

提出了低发泡硬质聚氯乙烯挤出成型的配方和工艺。研究了稳定型,改性剂等配方因素对制品密度、表面、泡孔结构的影响,并讨论了制品密度与挤出工艺的关系。     

双壁工业配件的吹塑成型

挤出吹塑一直被用于生产瓶、罐等包装容器,现正越来越多地用于生产工业配件。双壁吹塑制件已逐步应用于各行各业。双壁制件的吹塑主要以HDPE、PP、工程塑料及各种共混料为原料。本文着重介绍了双壁工业配件挤出吹塑的方法及设备设计要点。     

Strengthening of extruded composites with chemical fibres

The behavior of reinforcing chemical fibres in extrusion processing of a composite material was investigated. It was found that the degree of realization of the reinforcing effect of the chemical fibres was due to their nature and properties, in particular, the resistance to wear; this is especially important in conditions of processing by the extrusion method. The results of the study were used to make a well-founded selection of chemical fibres for strengthening polymeric composites with consideration of the technological features of the method of processing the material into articles. Translated from Khimicheskie Volokna, No. 4. pp. 26–28, July–August, 1998.     

Solid-phase backward extrusion of thermoplastics

The backward extrusion process was studied as a means of forming projections and ribs on flat sections of thermoplastic parts. The simplified, open-die axisymmetric and plane-strain extrusion cases were mainly considered. The results were applied to the development of a continuous solid-phase-forming process. Commercial-grade polycarbonate (PC), polypropylene (PP), and polystyrene (PS) were used in the investigation. The projection height and extrusion loads in the unconstrained extrusion were measured as a function of the initial temperature of the material, the load hold time, and geometric variables. Cold dies were used in the experiments, and the samples were kept below their melt temperatures. The dimensional recovery of the flange section of the formed samples was also measured as a function of the hold time for given initial temperature and geometric variables. The slab and the upper-bound methods-in plasticity analysis were used to theoretically derive the projection heights and forming loads. The degree of correlation between the predictions and the experimental results depended on the estimates used for the frictional factors at the interfaces between the deforming material and the dies.     

An Empirical Study on the Wear of Reciprocating Hydraulic Rod Seals Using 15 Different Oils

Hydraulic oils differ in their chemical composition and viscosity substantially. Their influence on the wear of rod seals is neither fully understood nor can be predicted precisely. The primary objective of this study was to evaluate the influence of various oils and their wetting properties on the wear of rod seals. In an empirical study, the wear of 30 commercially available polyurethane U-cups was investigated with 15 different oils using a recently built test rig. The wear of rod seals increased with lower viscosity and higher polarity of the oil. Both oil properties are combined in a new parameter which helps to assess the lubricity of oil and the wear of rod seals.     

Calculation of stresses in seals of chalcogenide glasses with other materials

The stresses in seals of chalcogenide glasses with other materials are calculated. The calculations are performed in the approximation of infinite flat seals of glasses with elastic materials and other glasses. It is shown that the results of calculations can be used for choosing materials of seals and conditions of their production and operation.     

Shrinkage and Warpage Optimization of Expanded‐Perlite‐Filled Polypropylene Composites in Extrusion‐Based Additive Manufacturing

A major challenge in extrusion‐based additive manufacturing is the lack of commercially available materials compared to those in well‐established processes like injection molding or extrusion. This study aims at expanding the material database by evaluating the feasibility of polypropylene, which is one of the most common and technologically relevant semicrystalline polymers. Expanded‐perlite‐filled polypropylene and ternary blends with amorphous polyolefins are evaluated to establish an understanding of their processability and their printability. A detailed study on the shrinkage behavior, as well as on the thermal, mechanical, morphological, and warpage properties is performed. It is found that smaller sized fillers result in a tremendous warpage and shrinkage reduction and concurrently improved mechanical properties than compounds filled with bigger sized fillers. Based on the optimal properties profile, a ternary blend that can overcome the shrinkage and warpage of printed parts is suggested.     

U型件的气体辅助挤出成型工艺的数值模拟与实验研究

应用Polyflow软件将气辅挤出成型引入U型件挤出成型过程中,建立了口模?气体?熔体的三相模型,在传热情况下,对口模温度、气体温度对口模内熔体的流动速度、温度及剪切速率等进行数值计算,用origin软件进行分析,通过传统挤出和气体辅助挤出成型对U型件进行挤出成型实验,选用聚丙烯（PP）材料挤出,均能顺利挤出,在达到挤出平衡后,气辅挤出时比传统挤出时更能使试样离膜下垂现象明显减弱。PP/10 %玻璃纤维在传统挤出成型时,有明显的挤出胀大现象,纤维在U型截面的侧壁与底面分布不均匀,在U型件拐角处分层分离现象严重;气辅挤出成型时,可以很好改善挤出胀大和纤维在侧壁与底面分布不均匀的现象,同时在U型件拐角处纤维分层分离的现象也能得到部分缓解。PP/20 %玻璃纤维在气辅挤出成型下挤出的U型件时,U型件壁厚变薄严重,试样中纤维分布比较均匀,拐角处无明显的纤维分层分离现象,但是试样表面有明显的纤维组织,且U型件的开口变形严重。结果表明,气辅挤出成型可以部分的减弱试样挤出后的下垂现象,也可以改善口模内熔体的温度场;传统挤出成型时候,口模内的U型件内外壁温度随着口模的变化而变化,气辅挤出成型时熔体高温区域集中在U型槽截面的中心线位置附近;气辅挤出成型与传统挤出时的剪切速率场分布发生了较大变化,气辅挤出成型时的剪切速率最大值比传统挤出时小很多。     

塑料在汽车工业上的应用及发展前景

介绍了塑料在汽车工业上的应用状况及发展前景。汽车用塑料零部件分为3类:内饰件、外饰件和功能件。汽车塑料内饰件主要有:仪表盘、车门内饰板、座椅等;汽车外饰件除要求具有内饰件的功能外,还要求强度高、韧性高、耐环境条件及耐冲击性能;主要汽车塑料外饰件有保险杠、翼子板等。功能件一般要有特殊的使用性能,主要汽车塑料功能件有:暖风机、空调类部件等。