Utilisation of maleic anhydride and epoxidised soyabean oil as compatibilisers for NBR/EPDM blends reinforced with modified and unmodified polypropylene fibres

Purpose - To evaluate the performance of the compatibiliser of epoxidised soyabean oil-free fatty acid prepared on the NBR/EPDM blends compared with maleic anhydride and also to explore the effect of loading the compatibiliser NBR/EPDM rubber blend with unmodified and modified polypropylene fibres on the mechanical properties of the blend. Design/methodology/approach - To achieve desirable rheological and physico-mechanical properties of NBR/EPDM rubber blend, various compositions were made by incorporating different doses of the compatibiliser of epoxidised soyabean oil-free fatty acid prepared and maleic anhydride to form NBR/EPDM blends. The effect of loading the compatibiliser rubber blend with unmodified and modified polypropylene fibres on the mechanical properties of the blend was investigated. Findings - The incorporation of epoxidised soyabean oil-free fatty acid or maleic anhydride into NBR/EPDM blend greatly enhanced their compatibility improved the rheological, as well as physical properties of rubber blends. The addition of NBR to EPDM improved the motor oil swelling resistance of EPDM. Blending of the two individual rubbers without a compatibiliser generally exhibited a non-synergistic effect with respect to the physical properties. The strain energy, tensile strength, Young's modulus and strain at yield varied linearly with composition in the presence of compatibiliser, but deviated from linearity in the absence of compatibiliser. Reinforcement of the NBR/EPDM blend with modified polypropylene fibres enhanced the physical properties more significantly than with the unmodified ones. Research limitations/implications - The compatibiliser of epoxidised soyabean oil was prepared by reacting in situ soyabean oil-free fatty acid with per-acetic acid. Practical implications - The method developed provided a simple and practical solution to improving the rheological and physico-mechanical properties of the NBR/EPDM rubber blend. Originality/value - The method for enhancing rheological and physico-mechanical properties of NBR/EPDM rubber blend loaded with modified polypropylene fibres was very important and showed a synergistic effect and could find numerous applications in the rubber and plastic industries.