An overview of challenges in processing of sustainable plant fiber composites

Abstract

Traditional composites often rely on synthetic fibers, raising environmental concerns due to their non-biodegradability and resource-intensive production. Consequently, sustainable composites have emerged as a potential substitute for these composites owing to their renewability, eco-friendliness, and biodegradability. Plant fibers are the key choice as reinforcement material for fabricating these composites. Researchers have explored the use of plant fibers to reinforce polymers, as a potential replacement for synthetic fibers, owing to the minimal environmental impact and contribution to carbon neutrality , lower greenhouse gas emissions, reduced energy consumption, and less dependence on fossil fuels . Flax, hemp, jute , ramie, etc., are some common examples of plant fibers with the potential to be used in various applications. However, several critical challenges persist in the processing of plant fiber composites , hindering widespread industrial adoption. The paper at hand provides a comprehensive overview and critically discusses challenges inherent to processing plant fiber-based polymer composites . It begins with an overview of common composite fabrication techniques , provides insight into the plant fiber structure, alongwith their mechanical properties and architectural configurations as reinforcements. A major challenge with these composites is the inherent hydrophilicity of plant fibers, leading to moisture absorption and swelling. The review explores absorption kinetics, including Fickian and non-Fickian models such as the Dual-Stage Fick’s Law and the Carter–Kibler two-phase (Langmuir) model, and also discusses the corresponding swelling kinetics. Another critical focus of this review is on the compaction and impregnation behavior of plant fiber preforms , highlighting issues such as compressibility , non-uniform resin flow , and mold filling inconsistencies. Thermal stability during processing is also discussed, particularly focusing on the thermal degradation thresholds of plant fibers. Each section concludes with a focused discussion on the underlying mechanisms, current mitigation strategies , and knowledge gaps. By consolidating insights across these domains, this review provides a foundational understanding of the interplay between plant fiber characteristics and processing phenomena.

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