Instrumental Physical Analysis of Microwaved Glycerol Citrate Foams

Abstract

Solid glycerol citrate polyester polymeric foams generated by microwave heating were further cured in a conventional oven at 100°C for 0, 6, 24, 48, or 72 h and their physical properties were tested. Curing glycerol citrate polyesters resulted in decreased moisture content (MC), altered color, increased hydrated polymer weight loss (HWL), and increased polymer oven weight loss (OWL). Polyester polymer samples were evaluated for firmness and springiness employing a texture analyzer (Model TA/TX2i). Oven curing increased polymer firmness and springiness. For example, firmness and springiness in 48 h cured samples increased 202 and 143%, respectively, when compared to uncured controls. High correlations were found comparing OWL, MC, HWL, firmness, and springiness. Compression molded samples obtained from ground cured and non-cured polymers were evaluated for tensile strength, elongation and Young's modulus using the Instron universal test machine (Model 4201). Curing promoted higher tensile strengths and elongation but did not affect Young's modulus values. High correlations were found between springiness, firmness, tensile strength, and elongation. The texture analyzer was shown to have merit in the preliminary evaluation of the glycerol citrate polyester polymers.