Polyamide 6–wheat straw composites: Effects of additives on physical and mechanical properties of the composite

Abstract Polyamide 6 was modified with lithium chloride (LiCl) salt and N ‐butyl benzenesulfonamide (N‐BBSA) plasticizer (additives). The modification was done in order to develop an environmentally friendly composite, composed of wheat straw (WS). A 15 wt% of ground WS was compounded with Polyamide 6 along with the additives. Addition of LiCl decreased the melting point of the matrix, allowing for a lower compounding temperature. However, a pseudo‐crosslinking formation upon addition of salt limited the polymer chain movement and restricted the processing temperature. LiCl addition increased the tensile and flexural modulus of the composite, but decreased the tensile and flexural strength. Decrease in the strength was found to be related to the increase in the residence time of material during extrusion causing severe WS thermal degradation. Addition of N‐BBSA eased the processing due to lubrication effect, however, when used in excess, lowered the flexural modulus and strength. Addition of WS to Polyamide 6 increased the modulus of the matrix. Matrix tensile modulus and flexural modulus were enhanced by 27%; however, a decrease in strength of the matrix was obtained. Addition of WS, LiCl, and plasticizer lowered the impact properties of Polyamide 6. It was concluded that combination of 2 wt% LiCl and of 2 wt% N‐BBSA gives the best mechanical properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers