Green composites based on recycled polyamide-6/recycled polypropylene kenaf composites: mechanical, thermal and morphological properties

Abstract The objective of this work was to investigate the effect of kenaf contents on mechanical, thermal and morphological properties of recycled polyamide-6 (rPA-6)/recycled polypropylene (rPP) blends. Kenaf was used to enhance the properties of composites. Alkali treating of kenaf by sodium hydroxide (NaOH) and combination with propylene grafted maleic anhydride (PPgMA) as a compatibilizer produced good adhesion both between rPP and rPA-6, and rPA-6/rPP and kenaf. Tensile, flexural and Izod impact tests were evaluated to study the mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were carried out to investigate thermal properties. Scanning electron microscopy (SEM) was performed for morphological analysis. Generally, the mechanical properties were successfully enhanced, especially Young’s modulus, flexural modulus, flexural strength and elongation at break, while there were some problems which caused the tensile strength and impact strength to be inferior. Thermal analysis showed that the crystallization of composites decreased as kenaf contents were increased. SEM showed a problem with kenaf and rPP/rPA-6 compatibility, which led to insufficient matrix at some places and agglomeration of kenaf at other places. Morphologically, there was unidirectional presence of kenaf in rPP main composites and random orientation in rPA-6 main composites.