Morphology and properties of bio-based poly (lactic acid)/high-density polyethylene blends and their glass fiber reinforced composites

Poly (lactic acid) (PLA)/high-density polyethylene (HDPE) blends of various proportions and their glass fiber reinforced composites were prepared by melt-compounding. The miscibility, phase morphology, thermal behavior and mechanical properties of the blends were investigated. The blends were immiscible systems with two typical morphologies, spherical droplet and co-continuous, and could be obtained at various compositions. Water contact angle and SEM images indicated that PLA and HDPE are immiscible but can be successfully compatibilized by ethylene-butyl acrylate-glycidyl methacrylate (PTW). Thermal degradation of all blends led to two weight losses, for PLA and HDPE. The incorporation of HDPE improved the thermal stability of the blend. With the addition of 5 wt% PTW, the impact strength of PLA/HDPE/PTW blends (60/40/5 w/w/w) is increased to 18.0 kJ/m2. The effect of glass fiber (GF) on the morphology and mechanical properties of PLA/HDPE/PTW blends (60/40/5 w/w/w) was also investigated. The addition of GF improved the thermal stability of the PLA/HDPE/PTW blends to some extent. The tensile strength of these blends increased and impact strength decreased with increasing GF content.