Effect of polypropylene on mechanical properties of polybutylene terephthalate/polyamide 6 blend

Abstract

This experiment was conducted to demonstrate that the use of the injection molding method of samples with different PBT/PA6 and PP blend ratios clearly shows the effect of the PP ratio on the mechanical properties of the blend to study and use the results for application in the manufacture of recycled plastic materials. PP/PBT/PA6 blends were mixed in the ratios of 100/0/0, 90/5/5, 80/10/10, 70/15/15 and 0/50/50. The tensile strength increased gradually, reaching the highest value in the 90PP/5PBT/5PA6 sample of 31.97 MPa, an increase of 18% compared to the 50PBT/50PA6 sample (27.1 MPa). The impact strength increased gradually from 2.83 kJ/m2 in the 70PP/15PBT/15PA6 sample to 3.55 kJ/m2 in the 90PP/5PBT/5PA6 sample, which was 5% higher than that of the sample without PP − 50PBT/50PA6. However, the flexural strength gradually decreases when adding PP to the blend, from 43.79 MPa in the sample without PP − 50PBT/50PA6 to 41.40 MPa at 80PP/10PBT/10PA6. The 50PBT/50PA6 sample had the highest stress value of 43.79 MPa. The hardness decreased gradually with increasing PP content; the value achieved at the 50PBT/50PA6 mixture was 80.2 MPa; however, at the 90PP/5PBT/5PA6 sample, the Shore D hardness achieved was 72.2 MPa. Therefore, increasing the PP content in the mixture will improve the tensile strength and impact strength but reduce the flexural strength and hardness of the sample. Our research results show that the 90PP/5PBT/5PA6 mixture has mechanical properties equivalent to PP plastic. Thus, instead of using 100% traditional PP plastic, the 90PP/5PBT/5PA6 mixture can be used, and PBT/PA6 material can be obtained from waste from producing toothbrush bristles, partly solving the plastic waste problem.