Investigation of the effect of addition of calcium stearate on the properties of low-density polyethylene/poly(ε-caprolactone) blends

Low-density polyethylene (LDPE) was blended with poly(ε-caprolactone) (PCL), prepared in proportions of 75/25, 50/50, and 25/75 (LDPE/PCL, wt/wt%). The effect of the addition of calcium stearate (CaSt) of these polymers was assessed by melting flow index, differential scanning calorimetry, tensile test, scanning electron microscopy (SEM), biodegradation in simulated soil with calcium determination, and enzymatic degradation. The addition of CaSt reduced the MFI of the PCL and of the 75/25 blend. The incorporation of 25 % of PCL slightly increased the T _m of LDPE. The tensile strength had no significant changes with the addition of CaSt and the polymers showed that they are incompatible according to this property. SEM showed poor interfacial interaction between PCL and LDPE, as well as that they are immiscible, and showed no significant changes on the morphology of the materials with the addition of CaSt. The results show that polymer samples after biodegradation in simulated soil present more calcium content than initial samples polymer. The soil analysis shows that the soil that contains the polymers submitted to thermal aging show smaller calcium content than the samples that were not aged. Lipase enzyme reinforced its specificity over PCL, and the addition of CaSt reduced the degradation of PCL and the 75/25 PCL/LDPE blend, however, it increased the rate of degradation of 50/50 and 25/75 blends.