Biobased composite materials obtained from unsaturated polyester resins and waste coffee

Abstract

Replacing styrene with biobased monomers to produce fully biobased unsaturated polyester resins (UPRs) turned out to be quite a challenging task. Styrene has been recognized as a hazardous and a potentially carcinogenic substance for human health. Using dimethyl itaconate as an alternative reactive diluent to styrene, which can be obtained from renewable resources, enables low viscosity for easy manipulation of mentioned UPRs. Fully biobased UPRs in question were based on itaconic acid, succinic acid, and propylene glycol, which were then diluted with dimethyl itaconate. Having in mind that UPRs can be used as a matrix for composite materials, this paper examines the effect of different weight ratios of spent coffee grounds as a filler. To determine the application of thus obtained composite materials, characterization consisted of examining mechanical properties based on viscosity measurements, uniaxial stretching experiments, FTIR spectroscopy and gel content analysis.