Optimization of biomass-to-water ratio and glycerol content to develop bioplastics from whole seaweed, Kappaphycus alvarezii

Many reports have described the development and properties of biodegradable plastics made from seaweed hydrocolloids, namely carrageenan, alginate, and agar. Although there is much potential, these seaweed extracts are expensive and require lengthy chemical treatment. In this study, the development of bioplastics using the whole biomass of red seaweed ( Kappaphycus alvarezii ) as base material, focusing on the optimization of the ratio of biomass (B) to water (W) and plasticizer (glycerol) concentration. The ratios (B: W) were 1:50, 1:60, 1:70, 1:80, and 1:90 (w/v), whereas glycerol was 1, 2, 3, 4 and 5% (v/v). The casting method was used for producing the bioplastics, and their physicochemical properties were tested using standard methods. As the water volume increases, tensile strength, colour intensity and opacity decrease while elongation-at-break and water vapour permeability increase. Similar trends were observed for the effect of increasing glycerol. All the bioplastics were fully degraded via soil burial within two weeks, and their shelf life lasted more than 14 weeks. Interestingly, the bioplastics developed at varied B: W ratios and glycerol concentration exhibit varied features that offer various applications, particularly food packaging.