An investigation on the possible use of coffee silverskin in PLA/PBS composites

The production of degradable packaging materials is a task that can be no lon-ger postponed. Moreover, high amounts of agricultural wastes are landfilledwithout any recycling. In this research, the possibility to formulate particulatecomposites made of biopolymers filled with coffee waste with acceptable physi-cal and mechanical characteristics that will degrade is investigated. The addi-tion of this agricultural waste, by reducing the requested amount ofbiopolymer, can decrease the overall price of the material presently the mainlimiting factor to the use of biopolymers in the packaging industry. Silverskin,the integument of coffee beans discarded during the roasting process, after amilling step, is added up to a 30 wt% either to polylactic acid (PLA) or to ablend of PLA and polybutylene succinate. The filler can be homogeneously dis-persed in both systems. The data shows that the silverskin filler increases theelastic modulus but decreases the tensile strength of the material and helps thedevelopment of crystal phase in the matrix. The thermal stability and thehydrophobicity of the materials stay almost unchanged on filler addition.Moreover, data shows that the addition of silverskin increases the materialssusceptibility to microbial attack.