As far as the tensile properties of natural fibres as reinforcements for composites are concerned, flax fibres will stay at the top-end. However, an efficient conversion of fibre properties into their corresponding composite properties has been a challenge, due to the fibre damages through the conventional textile methods utilised to process flax. These techniques impart disadvantageous features onto fibres at both micro- and meso-scale level, which in turn degrade the mechanical performances of flax fibre-reinforced composites (FFRC). Undulation of fibre is one of those detrimental features, which occurs during traditional fibre extraction from plant and fabric manufacturing routes. The undulation or waviness causes micro-compressive defects or ‘kink-bands’ in elementary flax fibres, which significantly undermines the performances of FFRC. Manufacturing flax fabric with minimal undulation could diminish the micro-compressive defects up to a substantial extent. In this research, nonwoven flax tapes of highly aligned flax fibres, blended with a small proportion of polylactic acid have been manufactured deploying a novel technique. Composites reinforced from those nonwoven tapes have been compared with composites reinforced with woven Hopsack fabrics and warp knitted unidirectional fabrics from flax, comprising undulating fibres. The composites reinforced with the highly aligned tapes have shown 33% higher fibre-bundle strength, and 57% higher fibre-bundle stiffness in comparison with the composites reinforced with Hopsack fabric. The results have been discussed in the light of fibre undulation, elementary fibre individualisation, homogeneity of fibre distribution, extent of resin rich areas and impregnation of the fibre lumens.

中文翻译：

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纤维结构改性以提高亚麻增强复合材料的拉伸性能

就作为复合材料增强材料的天然纤维的拉伸性能而言，亚麻纤维将保持领先地位。然而，由于用于加工亚麻的传统纺织方法会损坏纤维，因此将纤维特性有效地转换为其相应的复合特性一直是一个挑战。这些技术在微尺度和中尺度水平上赋予纤维不利的特征，这反过来降低了亚麻纤维增强复合材料 (FFRC) 的机械性能。纤维的波动是这些有害特征之一，它发生在从植物和织物制造路线中提取传统纤维的过程中。波动或波纹会导致基本亚麻纤维中的微压缩缺陷或“扭结带”，这显着破坏了 FFRC 的性能。制造具有最小波动的亚麻织物可以在很大程度上减少微压缩缺陷。在这项研究中，采用新技术制造了高度排列的亚麻纤维与少量聚乳酸混合的非织造亚麻带。由这些非织造带增强的复合材料与用机织 Hopsack 织物和由亚麻制成的经编单向织物增强的复合材料进行了比较，其中包含波浪形纤维。与使用 Hopsack 织物增强的复合材料相比，使用高度对齐的胶带增强的复合材料的纤维束强度提高了 33%，纤维束刚度提高了 57%。已经根据纤维波动、基本纤维个体化、纤维分布的均匀性对结果进行了讨论，