Preparation and characterization of non‐vulcanized natural rubber‐based cocoa pod husk composites

Several ingredients are often introduced into rubber matrices during the production of natural rubber (NR) based articles, essentially to modify and improve upon the properties of the final products as well as to reduce their costs. In this study, composites of natural rubber and cocoa pod husk were prepared by solution casting and tested for their rheological and thermal properties in order to ascertain the suitability of the latter as a substitute for standard fillers in the NR industry. An increase in the level of substitution significantly reduced the rheological properties of the composites in the linear viscoelastic region but had no significant effects on their thermal stability, glass transition temperature and on the α‐relaxation of the NR composites except at the highest level of substitution (25%). However, α‐relaxation and rheological shift factors were always temperature‐dependent and had a direct influence on their electrical conductivity with no permanent chemical bonds formed or broken during preparation of the composites. Hence, untreated cocoa pod husk could serve as non‐reinforcing filler for raw natural rubber. The cocoa pod husk is a cheap and environmental friendly material that is often considered as waste. Cocoa pod husk is a source of biofiller for non‐vulcanized natural rubber composites. In this study, composites of natural rubber and cocoa pod husk were prepared by solution mixing technique and tested for their rheological and thermal properties in order to ascertain the suitability of the latter as a substitute for standard fillers in the NR industry.