Reinforcement of the thermal stability and mechanical properties of low-density polyethylene/high-density polyethylene foam using a modified calcium sulfate whisker

Abstract

Radiation cross-linked low-density polyethylene (LDPE)/high-density polyethylene (HDPE) foams containing 30 wt% high-density polyethylene (HDPE) were further modified with different weight ratios (0, 4, 8, 12, and 16 wt%) of modified calcium sulfate whiskers (mCSW). The effects of mCSW content were investigated regarding the chemical structure, rheological structure, crystallization behavior, thermal stability, heat conductivity, cellular structure, and mechanical properties of the resulting LDPE/HDPE/mCSW foams. Consequently, the successfully synthesized mCSW could serve as the reinforcing filler and nucleating agent to improve the crystallization temperature, thermal stability, and mechanical properties of LDPE/HDPE/mCSW foams. The presence of mCSW influenced the LDPE/HDPE phase separation, which provided good interfacial compatibility and adhesion properties between the mCSW and the LDPE/HDPE matrix. In this case, the addition of 8 wt% mCSW increased the impact strength from 2.2 to 3.2 kJ m⁻² by ∼45.5% relative to the LDPE/HDPE foam. Similarly, the 8 wt% mCSW-reinforced LDPE/HDPE/mCSW foam produced homogeneous cellular structures and showed a considerable compressive strength of 239 KPa. Furthermore, the thermal stability of the LDPE/HDPE/mCSW foams also increased with increasing mCSW loading.