Original Article

Enhancing the mechanical performance of high-content straw/PLA biocomposites via talc and starch reinforcement

¹ Hebei University of Science and Technology 050018, PR China
² Arizona Institute of Industrial Technologyd, Hebei University of Technology, Tianjin, 300130, PR China

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Received: 8 November 2025
Accepted: 30 December 2025

Abstract

Wheat straw (WS) shows great potential as a reinforcing material for polylactic acid (PLA) composites. However, at high loading levels, this can lead to fiber embrittlement and poor interfacial adhesion. In this study, wheat straw was modified using a 3% NaOH solution and PLA and maleic anhydride-grafted PLA (MAH) as compatibilizers to evaluate the effect of varying talc-to-starch ratios on the properties of high-content wheat straw composites. SEM analysis indicates that NaOH modification removed impurities and increased fiber surface roughness, improving interfacial compatibility. The tensile strength, flexural strength and impact strength of the NaOH-modified composite were 12.7 MPa, 27.5 MPa and 8.8 kJ/m², respectively, 3.2, 2.45 and 2.38 times that of the unmodified composite. Upon incorporation of talc and starch into this formulation, talc alone markedly enhanced the tensile and flexural strengths of the composite, whereas starch alone improved the impact strength. When talc and starch were co-added at a 1:1 ratio, the composite exhibited the most balanced overall mechanical properties. However, when the talc-to-starch ratio was adjusted to 2:1 or 1:2, the mechanical properties of the composite deteriorated markedly. Comparative analysis indicated that the composite comprising 60% NaOH–modified wheat straw, 32% PLA, 7% MAH, and 1% talc exhibited the optimal overall reinforcement effect, achieving a tensile strength of 15.83 MPa, a flexural strength of 31.34 MPa, and an impact strength of 8.23 kJ/m².