Fabrication of Continuous Fiber-reinforced Thermoplastic Composites with Structural Gradient from Sheath-core Type Bicomponent Fibers

采用高速熔融纺丝工艺制备了以聚丙烯（PP）或聚碳酸酯（PC）为护套组分，热塑性液晶聚合物（TLCP）为芯部组分的套芯型双组分纤维。通过与PP或PC的协同处理，提高了TLCP可达到的最高卷取速度。PP/TLCP和PC/TLCP双组分纤维中TLCP组分的拉伸模量和强度随着卷取速度的增加而增加。以TLCP为增强纤维，PP或PC为基体聚合物，采用单轴排列双组分纤维压缩成型的方法制备连续纤维增强热塑性复合材料。对起始纤维和制备的复合材料的广角x射线衍射图进行了比较，结果表明TLCP在压缩成型过程中没有发生明显的取向松弛。因此，PP/TLCP和PC/TLCP复合材料的拉伸模量和强度与各自的双组分纤维更接近。各种类型的复合材料也由双组分纤维制成。在高速熔融纺丝过程中，通过改变纤套/纤芯的组成，将双组分纤维聚集在纺纱筒上进行压缩成型，制备出具有结构梯度的复合材料。通过制备双组分纤维，将261根微纤维包埋在一根双组分纤维中，制备了超细TLCP纤维增强复合材料。采用长丝缠绕法制备了双向和三向多层复合材料。正如层合理论所预测的那样，三向增强复合材料在层状面上表现出各向同性的拉伸模量。将双组分纤维编织成纺织织物，并对其进行压缩成型制备了三向增强复合材料。由此证明，以高速纺双组分纤维为起始材料，可以提高连续纤维增强热塑性复合材料的柔性设计。少

Sheath-core type bicomponent fibers consisting of polypropylene (PP) or polycarbonate (PC) as a sheath component and thermoplastic liquid crystalline polymer (TLCP) as a core component were prepared by the high-speed melt spinning process. The attainable highest take-up velocity of TLCP was improved by co-processing with PP or PC. Tensile modulus and strength of the TLCP component in the PP/TLCP and PC/TLCP bicomponent fibers increased with an increase in the take-up velocity. Continuous fiber reinforced thermoplastic composites, in which TLCP act as a reinforcing fiber and PP or PC as a matrix polymer, were fabricated by the compression molding of uni-axially aligned bicomponent fibers. Comparison of the wide-angle X-ray diffraction patterns of the starting fibers and fabricated composites indicated that the noticeable orientation relaxation of TLCP did not occur in the compression molding process. Accordingly, the tensile modulus and strength of the PP/TLCP and PC/TLCP composites wer … More e similar to those of the respective bicomponent fibers. Various types of composites were also fabricated from bicomponent fibers. Composites having structural gradient was fabricated by compression molding of bicomponent fibers accumulated on a bobbin by changing the sheath/core composition in the high-speed melt spinning process. Composites reinforced with ultra-fine TLCP fibers were fabricated through the preparation of bicomponent fibers in which 261 micro-fibers were embedded in a single bicomponent fiber. Bi-directional and tri-directional multi-layered composites were also prepared using the filament-winding method. As predicted by the lamination theory, composites with tri-directional reinforcement exhibited isotropic tensile modulus in the layered plane. The textile fabrics were woven from the bicomponent fibers and tri-directionally reinforced composites were fabricated by the compression molding of these fabrics. In this manner, it was proved that flexibility in the designing of continuous fiber reinforced thermoplastic composites can be improved by utilizing the high-speed spun bicomponent fibers as a starting material. Less