注塑型聚醚酰亚胺及其复合材料的性能及应用

本文介绍了注塑型聚醚酰亚胺(YS-30)及其复合材料的加工、性能及应用。     

聚醚酰亚胺对双马来酰亚胺烯丙基共聚物增韧改性

本文利用溶液法共混制备聚醚酰亚胺／双马亚酰亚胺烯丙基共聚物的共混树脂体系（即ＰＥＩ／ＢＭＩ／ＤＢＰＡ共混体系），并对其进行增韧研究，结果表明这种共混树脂具有良好的成型工艺性，其复合材料树脂基体韧性明显提高，而且该共混树脂体系可增强复合材料叠层板抗低速中击损伤性能。通过扫描电子显微镜观察发现这种热塑／热固共混体系具有独特的相太结构－－“韧性网络－－球粒”结构。     

聚醚酰亚胺热焓松驰的分子量依赖关系

采用ＤＳＣ对不同分子量的聚醚酰亚胺的等温及动态热焓松驰行为进行了研究，并以ＫＷＷ方程对实验数据进行了非线性拟合。结果表明，分子量对热焓松驰的影响是由高分子端基引起自由体积的差异所致。     

双醚二酐型聚醚酰亚胺的分子结构与透气性能

合成了一系列单环芳二胺型聚醚酰亚胺，研究了它们对Ｈ２、Ｏ２和Ｎ２３种气体的透过性能。这类双醚二酐（ＨＱＤＥＡ）型聚醚酰亚胺的分子结构对其透气性和透气选择性有很大的影响，随着二胺单体分子中甲基的增多，聚醚酰亚胺的透气性增大，透气选择性减小；由３，５－二氨基苯甲酸合成的ＨＱＥＤＡ－ＤＡＢ具有较高的透Ｈ２系数和很高的Ｈ２／Ｎ２分离系数。     

几种HQDEA型聚醚酰亚胺的透气性能

合成了四种双醚二酐(HQDEA)型聚醚酰亚胺,研究了它们对H_2、CO_2、O_2、N_2和CH_4五种气体的透过性能。结果表明,这类聚醚酰亚胺的分子结构,特别是取代基的位置对透气性和透气选择性有很大的影响。酰亚胺键邻位甲基取代聚醚酰亚胺(HQDEA-DMMDAI)兼具有高的透气性和透气选择性。     

聚醚酰亚胺平板超滤膜的制备

采用浊点滴定法研究发现,非溶剂添加剂(NSA)对聚醚酰亚胺(PEI)溶液的凝胶能力顺序为:γ-丁内酯(γ-GBL)<聚乙二醇400(PEG400)<正丁醇(BuOH)相似文献   

超临界二氧化碳/乙醇共发泡法制备聚醚酰亚胺泡沫制品

本工作采用一步泄压釜压发泡技术研究了聚醚酰亚胺(PEI)的超临界二氧化碳(scCO2 )发泡行为,系统研究了饱和压力、发泡温度和泄压速率对PEI泡孔结构的影响,进一步引入共发泡剂和成核剂来分别改善PEI的发泡性能和优化泡孔结构.通过釜压发泡熔接技术,在受限金属模具空腔中同时完成PEI珠粒的发泡与熔接,制备了发泡倍率及泡孔结构可调的PEI泡沫制品.结果表明,以scCO2 作发泡剂,发泡条件较为苛刻且所得PEI泡沫具有微孔结构,但整体发泡倍率小于3倍;加入共发泡剂如四氢呋喃(THF)和乙醇(EtOH)等可明显改善PEI的发泡性能、提升发泡倍率,引入碳纳米管(CNTs)作成核剂可显著优化泡孔结构、提高材料成核数量和泡孔密度;通过釜压发泡熔接制备的PEI及PEI/CNTs泡沫制品珠粒熔接质量良好,力学性能优良,PEI泡沫制品的拉伸强度和压缩强度分别为5. 7 MPa和5. 6 MPa.     

刚性二酐改性HQDEA—MDA型聚醚酰亚胺的透气性能

合成了一系列刚性二酐改性ＨＱＤＥＡ－ＭＤＡ型聚醚酰亚胺，研究了Ｈ２，Ｏ２和Ｎ２的透过性能与分子结构之间的关系，结果表明，在ＨＱＤＥＡ－ＭＤＡ分子中引入刚性或半刚必的第二种二酐单体后，在透Ｈ２系数有所提高的情况下，聚醚酰亚胺的Ｈ２／Ｎ２选择性明显改善，基中ＢＰＤＡ改性的聚醚酰亚胺ＨＱＤＥＡ／ＢＰＤＡ－ＭＤＡ的透气选择性最好。     

A STEP-compliant product data model for injection moulding products

In the current rapidly changing manufacturing environment, most manufacturing companies have realised that the ability to quickly develop a customised product at competitive prices is very crucial for them to survive in the keen competitive global market. Product modelling has been recognised as one of the key factors in determining the success of various product development strategies and for industrial competitiveness now and in the future. Standard for Exchange of Product model data (STEP) is an international standard designed to provide a complete, unambiguous, computer-readable definition of the physical and functional characteristic of a product through its lifecycle. This paper proposes a STEP-compliant product data model to fully support the complete product information representation and management for injection moulding product development. The data model is developed based on the structure of an injection moulding company. The entire data model consists of six data models which are defined to express information from various departments of the company. The data model is described in EXPRESS language, which can be integrated with other STEP-based product data models and databases. Consequently, the proposed system can be further extended for helping other injection moulding manufacturers to improve their product development process. An information sharing prototype system is implemented based on the proposed product data model to demonstrate the feasibility of the approach.     

Vacuum injection moulding for large structural applications

Resin Transfer Moulding (RTM) is a successful closed mould technology for small composite products in large series. For large products in smaller series (i.e. boat hulls or rotor blades) the Vacuum Assisted RTM is applied in order to save cost of moulds. Compared with RTM the VARTM technology is still not practised in many products today. The risk of failures in very large products is often considered too high. This paper describes ways to improve reliability and predictability of the VARTM technology in order to decrease development cost and to make the risk of failures during production as small as possible. First, appropriate methods to achieve void free processing of the composite material are described. Secondly, it is explained how the injection strategy can be optimised by using resin flow simulation software. Two examples of successful developments of large structural applications are described; a 20 m rotor blade and a 16 m long boat hull for a sailing yacht.

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Selection of a powder for ceramic injection moulding

Ceramic suspensions were prepared from six alumina powders using the same high molecular weight organic vehicle. 18 mm diameter cylinders were compression moulded from four of these suspensions which were suitable for ceramic injection moulding. The organic vehicle in each cylinder was removed by thermal degradation according to the same temperature ramp. The defects present in the cylinders after removal of the organic vehicle are discussed in terms of the powder characteristics. Criteria for the selection of ceramic powders that could be used together with a high molecular weight organic vehicle for this shape-forming method, are deduced from the results obtained.     

Enhanced properties of lignin-based biodegradable polymer composites using injection moulding process

Composites from polybutylene succinate (PBS) and lignin-based natural material were fabricated using a melt mixing process. The effects of lignin material and polymeric methylene diphenyl diisocyanate (PMDI) compatibilizer on the properties of composites were investigated. Incorporation of 65% lignin material into PBS was achieved with an improvement in the tensile and flexural properties of composites. Incorporation of 1% PMDI in 50% lignin filled composites enhanced the tensile, flexural and impact strength simultaneously. Heat deflection temperature (HDT) of the virgin plastic also increased with lignin and PMDI incorporation. Improved interfacial adhesion was observed from SEM micrographs of the compatibilized composites.     

Properties of ceramic injection moulding formulations

The rheological properties of nine ceramic injection moulding compositions based on polypropylene with a fled silicon powder loading were measured. Minor components of the polymer-ceramic blend were shown to have a considerable effect on the properties of the melt. An attempt was made to derive, from capillary rheometer flow curves, the parameters which are thought to influence moulding quality. !n particular, the shear rate dependence of viscosity at the nozzle temperature, fluidity ate shear rate of 100 sec^?1, the temperature dependence of viscosity in the region of the nozzle temperature and at o shear rate of 100 sec^?1 and the yield stress are discussed. !n Part 2 the influence of these variables and other properties of the formulations, on quality of moulding will be considered.     

Properties of ceramic injection moulding formulations

The oxidative and thermal degradation of nine suspensions, with polypropylene as the main organic component and a fixed silicon powder loading, were studied by thermogravimetry. Samples were in the form of finely divided shavings and moulded bodies. The acceleration of weight loss in oxidizing atmospheres was dependent on sample size, indicating oxygen diffusion control. Minor additions in the formulations exerted considerable influence on the form of the thermograms. Samples heated in nitrogen presented an exfoliated skin defect which did not appear in oxidizing atmospheres. An important observation was that the form of the thermogram could not be directly related to the incidence of defects in the powder assembly and was therefore an incomplete guide in the screening of potential blends. Nevertheless, a low temperature dependence of weight loss was shown to be desirable for process control.     

Rheology of composite ceramic injection moulding suspensions

Ceramic injection moulding compositions incorporating sinterable silicon nitride powder and silicon carbide whiskers were prepared by twin screw extrusion using a polypropylene-based organic vehicle. Their viscosities in the shear rate range 100 to 1400 sec^–1 were measured by capillary rheometry. The relative viscosity ( _r)-ceramic volume loading (V) curve fitted the Chong equation

Thermal conductivity of metal powder-polymer feedstock for powder injection moulding

Thermal conductivity of a powder injection moulding feedstock (mixture of metal powders and polymers) in solid and molten states has been measured by using the laser flash method. The filler material was 316L stainless steel powder and its content in the mixture amounted 60% by volume. An attempt has been made to employ two most promising existing mathematical models (theoretical Maxwell- and semi-theoretical Lewis & Nielsen model) to calculate the thermal conductivity of the mixture. Comparison of the experimental and calculated results has revealed that the Lewis & Nielsen model predicts better than Maxwell model the thermal conductivity of the feedstock. As the difference between the calculated (Maxwell model) and the measured results amounts to 15–85%, it is suggested that it can only be used for preliminary assessment of the thermal conductivity of so highly filled composite material. If accurate thermal conductivity data are required (as in case of numerical simulation of the powder injection moulding process), measurement of this property has to be performed if meaningful simulation results are to be expected.     

Rheological behaviour of a polymer-ceramic blend used for injection moulding

Our aim is to describe the behaviour of highly filled injection moulding pastes, made of a polymer binder and fine ceramic powders. A specific rheometer has been developed to characterize this behaviour within the injection range of pressures and shear rates. As classical homogeneous models fail to describe the behaviour of the paste, we propose an original model deriving from the mixture theory, taking into account the separate contributions of binder and powder to the global behaviour of the paste. The qualitative and quantitative accuracies of this model are discussed.