Polylactic acid/epoxidized natural rubber biofoams: modelling and water absorption

Abstract

Biofoams containing polylactic acid (PLA) and an epoxidized natural rubber (ENR-50) were prepared using various chemical foaming agents (CFA). The factors that affect the properties and characteristics of the biodegradable foams were epoxidized natural rubber (ENR)-50 and CFA contents. ENR-50 is one of the toughening agents used for blending with PLA by twin-screw extruder followed by compression moulding. Water absorption increased with increasing ENR-50 and CFA contents, due to the effect of polarity and natural hydrophilicity of the oxirane groups of ENR-50. The percentage crystallinity decreased with the addition of ENR-50 and CFA, due to the interaction between the epoxy groups of the ENR-50 and the carbonyl groups of the PLA, which makes movement more difficult and hinders the arrangement of the crystal. The addition of ENR in blend foam led to the increase of impact strength. Whereas the flexural strength of PLA/ENR foams decreased with increased ENR content. The impact strength and flexural strength of PLA/ENR-50 foams were investigated and the experimental data were analysed through SPSS and MATLAB, to optimize as well as to determine the significance of the factors affecting the impact strength and flexural strength of the foams. The parameterization of the mathematical method for different content of the initial controlled substance was achieved by fitting the mathematical model with the experimental data for impact strength and flexural strength. The 3-D curves obtained from the proposed mathematical models were plotted.