原位成纤技术研究进展

描述了原位成纤技术的增强机理,综述了影响原位成纤的主要因素,指出原位成纤技术现存的问题,并对原位成纤技术的发展进行了展望。     

原位成纤复合材料研究进展

综述了近年来利用原位成纤技术增强复合材料的研究现状,介绍了原位成纤技术的增强机理和影响因素,总结了不同体系原位增强复合材料的性能特点和最优的成纤加工条件。最后对原位成纤复合材料的发展进行了展望。     

丙烯腈-醋酸乙烯酯共聚物的沉淀分级

聚丙烯腈纤维和丙烯腈与其他某些单体共聚物纤维(俗称人造羊毛)具有许多优良的性能,是合成纤维中重要的一类。但这类高聚物能否成纤及成纤后的性能与其平均分子量及分子量分布有密切关系。霍鸟茨(R.C.Houtz)认为用来制造纤维的聚丙烯腈的数均分子量应在40,000～80,000之间。一般说,在合适的成纤聚合物中低分子物含量愈多,成纤后的性能也愈     

原位复合成纤增强技术

介绍了2类原位复合成纤增强体系，分别讨论了它们的成纤机理，影响成纤的条件及组分间的相互影响；并概要地叙述了目前国内外在这些领域内所取得的进展。     

原位成纤增强POE弹性体的制备

利用双螺杆熔融挤出-微纳叠层共挤方法制备了POE/PP原位成纤增强复合材料,通过扫描电子显微镜(SEM)研究了POE/PP原位成纤增强复合材料的形态,结果表明:分散相PP在POE基体中形成了长径比很大的微纤,且微纤粗细较均匀;对POE/PP原位成纤增强复合材料的动态力学研究表明:分散相PP的添加,能够使POE基体的储能模量大幅提高,损耗因子明显下降;拉伸测试研究表明:PP微纤的形成显著提高了POE弹性体的拉伸强度,当PP质量分数为30%时,POE/PP原位成纤增强复合材料的拉伸强度是纯POE的2.92倍。     

聚丙烯基原位成纤复合材料研究进展

以聚对苯二甲酸乙二酯(PET)、尼龙(PA)66、PA6、超高分子量聚乙烯(UHMWPE)、聚苯硫醚(PPS)、聚萘二甲酸乙二酯(PEN)等热塑性树脂为成纤聚合物,综述了利用这些成纤聚合物制备聚丙烯(PP)基原位成纤复合材料的方法、技术及复合材料的结构特征、力学性能.提出了优化PP基原位成纤复合材料综合力学性能的思路.     

聚合物原位成纤方法及其在PP共混体系中的应用

介绍了聚合物共混体系原位成纤原理、影响因素、制备方法及聚丙烯(PP)与其他聚合物原位成纤共混体系研究进展,包括PP/聚酰胺(PA)、PP/聚对苯二甲酸乙二醇酯(PET)原位成纤共混体系等.重点阐述了不同共混比、相容性、黏度比和加工参数(如拉伸速率、螺杆转速、加工温度等)等对PA或PET在PP中的成纤形态和PP力学性能、...     

熔融与成纤：生产普通硅酸铝纤维的两个关键环节

作者结合生产实践,对普通硅酸铝纤维的两道主要生产工序——熔融与成纤的二艺方法作了对比评述。在熔融中对比了电弧炉和电阻炉,在成形工艺中对比了喷吹法与离心法。为了提高产质量和节约用电,作者认为在普通硅酸铝纤维生产中,在工艺上最好采用电阻炉和离心法成纤工艺。     

分散相含量对HDPE/PA6原位成纤增强复合材料性能的影响

采用熔融挤出-微纳叠层共挤制备了HDPE/PA6原位成纤增强复合材料,通过SEM分析了分散相PA6含量对其在基体中的形态及分布的影响;讨论了两种加工方式下分散相PA6含量对复合材料静态力学性能和耐热性能的影响以及加工方式对复合体系力学性能的作用。结果表明:在原位成纤增强复合材料中存在直径为2～5μm的纤维,当HDPE/PA6质量比为85/15时,微纤直径约为3μm,此时,与普通共混体系相比,原位成纤增强复合体系的拉伸强度提高了6.9%,拉伸模量提高了14.8%,冲击强度提高10.03%;随PA6含量的增加,原位成纤增强复合体系维卡软化温度明显提高,PA6质量分数为25%时比普通共混体系提高8.8℃。     

新型成纤聚酯的开发

本文对国外开发的新型成纤聚酯进行了评述,着重介绍七种有实际生产意义的新型成纤聚酯的结构特点,以及由这些聚酯制备的纤维的主要性能和用途.     

热塑性聚合物原位成纤研究进展

综述了近年来柔性链聚合物原位成纤技术的研究成果，简要介绍了原位复合材料的力学性能、增强增韧机理，着重总结了微纤形成条件和影响因素。     

PPTA纤维原纤化的研究进展

阐述了聚对苯二甲酰对苯二胺(PPTA)纤维的结晶结构及其原纤化的机理,综述了国内外PPTA纤维原纤化的研究进展。PPTA纤维具有皮芯结构,芯层含有高度取向的多重原纤。PPTA浆粕的制备方法主要分为机械法以及直接成型法,其关键技术在于控制纤维原纤化程度,保持纤维强度以及解决分散性能。机械法制备浆粕的方法包括磨浆设备的改进,在聚合体系中添加其他聚合物改善纤维的磨浆性能以及混合其他易原纤化纤维磨浆等。直接成型法包括沉析法和凝胶法,相对于机械法制浆,直接成型法具有工艺流程简单的优点,但是使用此方法制备浆粕,难以控制原纤的形状,纤维强度低。     

干法异形腈纶纤维工业开发初探

与湿法腈纶纺丝成形工艺相比 ,干法腈纶纺丝成形条件严格 ,成形过程复杂。因此 ,干法腈纶差别化产品远少于湿法腈纶。国内科研单位及干法腈纶生产企业都正在进行干法腈纶新产品的开发与研究。本文在工业装置进行探索开发实验基础上 ,对干法异形腈纶纤维的纺丝成形进行初步研究探讨 ,分析了纺丝成形规律 ,对进一步开发实验提出了建议和看法     

差别化聚酰胺6纤维的研究进展

介绍了原位聚合、物理共混、复合纺丝和后处理等技术制备差别化聚酰胺6(PA6)纤维的方法,探讨了特黑超细PA6纤维、阻燃PA6纤维和导电PA6纤维的国内外研究进展。     

Microstructural analysis of in situ mesophase transformation in the fabrication of carbon-carbon composites

In this work, we examined the microstructures formed during the pyrolysis of naphthalene mixed with AlCl₃ catalyst, in the critical temperature range of 300-500 °C and at varying pressures. In addition, non-rigidized preforms were densified by multiple cycle in situ transformation and compared the process with impregnation using fully transformed AR mesophase pitch under similar conditions. The process of mesophase formation in the bulk phase and within tightly packed fiber bundles was observed to be similar: spherule nucleation from the isotropic phase, coalescence of spherules forming bulk mesophase, and mesophase flow before hardening. The hardened mesophase displays the coarse, fibrous, and lamellar microstructure observed in needle cokes. The molten naphthalene was observed to evenly penetrate in-depth the large void spaces and fiber bundles. After two in situ cycles, the fiber bundles and the inter-fiber bundle regions were well filled with transformed mesophase. The incremental filling of the larger void spaces reduced the calculated filling efficiencies from 47% in the first cycle to below 15% in the third through fifth cycle. An 8% improvement in densification efficiencies was achieved by applying modest pressures during the pyrolysis. The extent of mesophase penetration with AR mesophase was observed to decrease from the outer to the inner regions of the preform. The results suggest impregnation with naphthalene catalyst mixture is efficient in filling tightly packed fiber bundles but not large void spaces. Multiple cycles are required in order to fill the large void spaces.     

木质素碱催化苯酚液化物纤维固化工艺

以木质素碱催化苯酚液化物为原料,加入六次甲基四胺后熔融纺丝,将熔纺纤维置于甲醛和盐酸混合溶液中固化处理制得固化纤维,研究了碱存在条件下木质素苯酚液化物的成纤性及初生纤维固化条件。结果表明:木质素碱催化苯酚液化物具有很好的成纤性;所得纤维性能与纺丝条件和固化工艺相关。在收丝辊转速450r/min、压力0.02 MPa、固化液盐酸质量分数15%、甲醛质量分数18.5%、固化温度95℃、升温速率10℃/h、固化时间4 h条件下,所得纤维性能较好,适于制备碳纤维。     

Bulge forming of braided thermoplastic composite tubes under axial compression and internal pressure

In this study, the bulge forming of fiber reinforced thermoplastic (FRTP) composite braided tubes was studied as a new forming technique utilizing fiber orientation rearrangement (the trellis effect) at temperatures near the matrix melting point. It is shown that free bulge forming with the trellis effect can easily result in high expansion without buckling only by axial compression. This is when the stress of the matrix is small enough to rearrange the fiber orientation of the braid. To improve the surface quality and dimensional accuracy, bulge forming with closed dies and internal pressure was also examined experimentally. The appropriate conditions for axial penetration and internal pressure are established. The kinematics of braid is also considered, and calculations from the model are evaluated from experiments. In addition, the kinematic state of braid after deformation is simulated by calculation from the geometric braid model. It is found that the “normalized profile” of the bulged tube does not change during the process and the thickness of the matrix depends on changing fiber orientation.     

聚乳酸纤维的研究进展及应用

介绍了目前聚乳酸国内外的发展现状,阐述了聚乳酸的合成及纤维成形,并简要概括了其性能特征和应用领域。聚乳酸目前在国内外的发展呈现出多元化、多方向研究的状态,主要以美、德、日、中为主;其合成现阶段的研究集中在丙交酯开环聚合上;熔融纺聚乳酸纤维工业化生产技术比较成熟,溶液纺丝、静电纺丝等其他方式均处于研究阶段,而更多的关注点在于对聚乳酸的物理、化学、生物改性来扩展其应用。聚乳酸纤维具有优良的性能,因此被广泛应用于服装、生物医学、农林牧渔等行业,有巨大的应用前景和发展空间。     

Effects of spinning conditions on structure and properties of multifunctional fibers of polyimidoamide nanocomposites

The effects of basic fiber‐forming parameters on the porous structure, moisture absorption, and strength properties of fibers from polyimidoamide nanocomposites were examined. Beneficial fiber‐forming conditions were established in consideration of the fiber sorption and strength properties. It was found that the incorporation of montmorillonite into the fiber‐forming polymer resulted in beneficial increases in fiber porosity and internal surface area. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3323–3331, 2006     

Modeling and simulation of the vacuum forming of wood fiber–filled thermoplastic composites

Vacuum forming of wood fiber–filled thermoplastic composite sheets has become an important process in the industry because of their low cost, good formability, and high strength to weight. Nonuniform thickness distribution of a vacuum formed part caused by inappropriate mold design and processing condition is one of the problems that confound the overall success of this technique. A novel viscoelastic model of two-dimensional finite element scheme, with eight noded overlay isoparametric elements was developed to numerically simulate the vacuum forming of wood fiber filled isotactic polypropylene. Computed results are in agreement with literature experimental data. Numerical simulation of a vacuum forming process can be used to optimize the molds and the forming parameters to achieve a product with ideal thickness distribution.