ABSTRACT A dense polyimide (PI) composite reinforced by quartz fibres (QFs), was prepared by vacuum assisted polymer infiltration and hot-pressing in this work. The microstructures and the mechanical properties of the as-fabricated composites were investigated. The results show a high flexural strength (≈686 MPa) of the composite, due to its dense nature. Moreover, there was no significant change in the bending strength of the stitched composites. The laminates mainly suffered delaminations and fracture of the QFs. The intralaminar bonding of the composite was enhanced by a novel stitching technique (all 28 layers stitched together by untwisted quartz filament tows in the plain stitch). As a result, the interlaminar fracture energy with 1 stitches cm−2 stitch density was increased by 87.1%, compared to that of the unstitched composite. In the case of stitched specimens, stitching plays an important role in improving the Gc and suppresses the influence of in-plane fibre orientation.

中文翻译：

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一种新型石英纤维增强致密聚酰亚胺基复合材料：预制件缝合效果

摘要 在这项工作中，通过真空辅助聚合物渗透和热压制备了一种由石英纤维 (QFs) 增强的致密聚酰亚胺 (PI) 复合材料。研究了制备的复合材料的微观结构和力学性能。结果表明，由于其致密性，复合材料具有高弯曲强度 (≈686 MPa)。此外，缝合复合材料的弯曲强度没有显着变化。层压板主要遭受 QF 的分层和断裂。复合材料的层内粘合通过一种新颖的缝合技术得到增强（所有 28 层都通过平针中的无捻石英丝束缝合在一起）。结果，与未缝合的复合材料相比，1 针 cm−2 针迹密度的层间断裂能增加了 87.1%。