Miscibility and Biodegradability Studies of Polystyrene/Linseed Oil Epoxy Blend Derived from a Sustainable Resource

This study highlights the utilization of linseed oil epoxy (LOE) (a product from a sustainable resource), to obtain blends of LOE with polystyrene (PS) forming tough and flexible free-standing films. The blends were prepared by mechanical mixing of the requisite amounts of the two components in the weight ratios of LOE/PS are 85/15, 65/35, 55/45, 45/55, 35/65, and 15/85 through a solution method by mixing in tetrahydrofuran. Free-standing films of the blend were cast. The miscibility of the two components in a solution phase was investigated by reduced as well as relative viscosities and density measurements while the miscibility in a solid phase was examined by scanning electron microscopy (SEM). At all the concentrations, calculated values of reduced viscosity were found to be higher than the observed values of the reduced viscosity for the blends with 15-85 wt% of PS. Viscosity measurements reveal that miscibility occurs between the composition range of LOE/PS 85/15 to 45/55. At composition LOE/PS 35/65, phase inversion takes place which indicates the onset of immiscibility of the two components in the solution phase. The immiscibility of the two compositions at this composition (LOE/PS 35/65) is also shown by the SEM micrographs which exhibits two distinct phases. The mechanical properties of LOE/PS blend films were found to match with LDPE at composition LOE/PS 65/35. The potential applications for such sustainable resource based blend include packaging films and production biodegradable plastic sheets which can be formed into products such as bio-bags.