Brittle-ductile transition of elastomer toughened HDPE: effect of elastomer modulus

Impact resistance for elastomer toughened high density polyethylene (HDPE) at low temperature was determined by its brittle-ductile transition temperature (T-BD). Following our previous work, i.e. the effect of HDPE molecular weight on the brittle-ductile transition of POE toughened HDPE (Wang et al. in J Polym Res 29:1-8, 2022), we studied the effect of elastomer modulus because the modules ratio of matrix polymer to elastomer plays an important role in brittle-ductile transition. In this study, four elastomers with different glass transition temperatures (T-g) were employed. The modules ratios of the HDPE to the elastomers were obtained by dynamic mechanical analysis (DMA) measurement, respectively. The notched impact strengths for the HDPE blends with different elastomers were tested at various temperatures. The results showed that the notched impact strength appeared a clear sharp transition when the modulus ratio of the HDPE to elastomer reached 10 by increasing temperature, indicating that the HDPE could not be toughened effectively when the modulus ratio of the HDPE to elastomer is smaller than 10. This is the first time to quantitatively give the effect of elastomer toughened thermal plastic polymers on the brittle-ductile transition in experiment. Moreover, the result directly indicated that the T-g of elastomer must be low enough in order to obtain lower T-BD of elastomer toughened HDPE.