Thermoplastic Elastomer Biocomposites Filled with Cereal Straw Fibers Obtained with Different Processing Methods—Preparation and Properties

This work is focused on thermoplastic elastomers composites (TPEs) reinforced with straw. Crop waste with different particle size was used as a filler of ethylene-octene rubber (EOR). Application of cheap and renewable natural fiber like straw into a TPE medium is not fully recognized and explored. The effect of fiber orientation induced by two processing techniques on the different mechanical properties of composites was investigated. Microscopic images were used to present the tested straw fractions and observe the arrangement and dispersion of fibers in the polymer matrix. It was found that the usage of an injection molding process allowed for the forming of a more homogenous dispersion of short fiber particles in the elastomer matrix. An oriented straw filler and polymer chains resulted in the improved mechanical strength of the whole system as evidenced by the obtained values of tensile strength almost two times higher for injected composites. In addition, all composites showed very good resistance to thermo-oxidative aging, where the aging factor oscillated within the limits of one, regardless of the processing method and the amount of bioadditive used. On the other hand, vulcanized composites were characterized by greater tear resistance, for which Fmit values increased by up to 600% compared to the reference sample.