Abstract
The thermal stability and the thermal expansion of wheat straw flour filled polypropylene and high density polyethylene composites were studied using thermogravimetric analysis and thermomechanical analysis. The results of this study showed that the thermal degradation and the thermal expansion of the composites were affected by plastic type and compatibilizer. The thermal stability of HDPE-based composites was found to be higher than that of PP-based ones. Adding compatibilizer to the composites boosted the thermal stability of agro-filler thermoplastic composites by improving the adhesion between wheat straw flour and the matrices. The thermal degradation activation energy of pure PP and HDPE was higher than that of the composites. The activation energy of compatibilized composites was slightly higher than uncompatibilized ones. TMA results indicated that wheat straw flour was a suitable material for decreasing the thermal expansion of the composites caused by cold and warm atmospheric changes. The thermal expansion of PP and wheat straw flour filled polypropylene composites was found to be lower than that of HDPE and HDPE-based composites.