Effect of sequential melting and sintering on foam processability of <scp>UHMWPE</scp> / <scp>LDPE</scp> blends

Abstract UHMWPE inherits difficult foam processability, which could be enhanced by blending it with lower molecular‐weight polyolefins. In our previous work, the UHMWPE/LDPE (UL) blend was prepared with varying LDPE content (10, 20, 30, 40, and 50 wt.%), and their properties were analyzed. In the current work, the effect of the simultaneous melting and sintering mechanism on the foam processability of UL blends was studied. The LDPE content influenced the foam morphology and compression properties. LDPE improved UHMWPE's foaming window and processability. At low temperature, bimodal, and at higher temperatures, trimodal cellular structure was predominant in UL foam samples containing 30 wt.% LDPE content and above. In contrast, the samples containing less than 30 wt.% of LDPE content were partially foamed. The foam samples with up to 30 wt.% LDPE content had smaller foam cell sizes and a density range of 0.9–0.6 g/cm 3 . The foam samples having more than 30 wt.% of LDPE content showed uniform foaming with lower foam density (0.35–0.15 g/cm 3 ) and a higher expansion ratio (2–10.5). The foam compression modulus decreased below and above 30 wt.% of LDPE content in blends. Hence, 30 wt.% of LDPE in the blend represents the threshold concentration to develop specified foam morphology and performance properties. Highlights Effect of melting and sintering mechanism on foam processability of UL blends. Widening of the foaming window of UHMWPE. Effect of critical concentration on the foaming behavior of UL blends. Bimodal and trimodal cellular structure formation in UL foam samples. Wide range of compression modulus and strength obtained for the UL foams.