Alignment of Short Fibres: An Overview

Fibre orientation is a major factor influencing composite performance; research, largely on synthetic fibre composites, supports that the best mechanical performances are achieved in composites when fibres are aligned in the loading direction. Generally, with short natural plant fibre (SNPF) composites, randomly oriented fibre mats are used as reinforcements due to the innate limits of fibre length and the difficulty of aligning short fibre. However, there are a number of methods that have been developed for aligning short fibre, again largely employed for synthetic fibres. The two main approaches employed to align short fibres relate to whether dry or wet processing is used available in literature; in wet processes, fibres are generally suspended in a liquid medium and alignment of fibre trails the fluid flow direction, whereas in dry processes, dry fibres are aligned in the direction of an induced or applied force such as pneumatic or electric. An overview of different alignment methods with their working principles is presented in this paper. This paper also describes an alignment technique currently under development to improve the alignment obtained for SNPFs