Bio‐based polyurethanes (PUs) were synthesized from castor oil (CO) and poly(3‐hydroxybutyrate)‐diol (PHB‐diol) using 1,6‐hexamethylene diisocyanate, as nontoxic connecting agent. The PHB content in the obtained PUs was adjusted from 0 to 60.0 wt%. The synthesis was carried out by one pot solution polymerization. PUs nanocomposites loaded with different contents of cloisite®25A (C25A) were prepared by means of in situ solution polymerization. The molecular structure of the obtained PUs was confirmed by FT‐IR. The thermal properties of the neat PUs and the resulting nanocomposites were investigated using DSC and TGA. It was found that the cold crystallization of the PHB component was enhanced, while its melt crystallization was retarded with increasing its own content in the PUs. The incorporated C25A in the PU matrix shifted the cold crystallization peak to higher temperature. TGA studies reveal that neat PUs and nanocomposites exhibited three main decompositions steps. The thermal stability of the neat PUs decreased with increasing the PHB content and increased with increasing the C25A content. Tensile mechanical testing revealed that increasing the content of the PHB and C25A made the PUs rigid and strong. The elastic modulus and ultimate tensile strength of the neat PUs were found to increase with increasing the PHB content and enhanced with incorporation of C25A, while the elongation decreased with increasing the PHB and C25A content. The equilibrium swelling in 1,2‐dichloroethane decreased with increasing both the PHB and C25A content in PU matrix. POLYM. COMPOS., 39:E489–E499, 2018. © 2017 Society of Plastics Engineers

Water vapor permeability (WVP) is an important parameter for systems used in edible coatings of food. WVP should be optimized to a minimum value to control the passage of fluids between food and its environment. In this work, Box-Behnken design was applied to optimize the edible coating based on alginate, soluble starch and microcrystalline cellulose (MCC) to its minimum. The optimized theoretical value of WVP was 9.94 g mm/m2 day kPa which was in agreement with the experimental obtained value. The molecular structure of the prepared edible coating films was verified using FTIR. MCC addition significantly improved the thermal and mechanical properties of the edible coating. Shelf-life studies on green capsicums coated with the optimized edible system showed great resistance to mass loss and spoilage. The prepared edible coating, based on the excellent obtained data, could be used potentially to extend the shelf-life of food.