Thermomechanical Properties of Corn Starch Based Film Reinforced with Coffee Ground Waste as Renewable Resource

Abstract

Starches polymeric films offer several advantages for the replacement of synthetic polymers due to their biodegradability, non-toxicity, availability and low cost. However, the high biodegradation potential can cause fragility, considering some fundamental mechanical properties. Therefore, starch based polymeric films were reinforced incorporating lignocellulosic waste from coffee grounds postconsume. The effect of incorporation of coffee ground in cornstarch matrix and polymer interaction on morphology, thermal and mechanical properties were investigated. The characterization analyzes were based on Dynamic Mechanical Thermal Analysis (DMTA), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Scanning Eletronic Microscopy (SEM). The coffee ground behaved as reinforcement agent according tensile values. Thermochemical conversion showed that polymeric films molding did not change his thermal stability. In temperature range was possible to observe the devolatilization, organic and inorganic compounds decomposition. SEM images showed the coffee ground adhesion in the polymer matrix promoting a better mechanical tensile strength.

Developing thermoplastic corn starch composites filled with brewer's spent grain for applications in biodegradable films

“…[42] Since lower amounts of water were used in the production of the composites, the incorporation of BSG fibers resulted in higher temperatures for the evaporation of residual water, similar to the behavior reported by other authors who used different lignocellulosic fillers in TPS composites. [21] A second endothermic peak observed in the range of 125-180 C is attributed to the melting of the crystalline portion of the polymer matrix. [42] As shown in Table 6, the addition of BSG fibers resulted in an increase in the melting temperature (T m ) of the composites compared to pure TPS (135 C), which was higher for C35-2.5 (151 C) than for C100-1 (139 C).…”

“…[1,17] Lignocellulosic by-products from different agroindustrial processes have also been widely studied to develop starch-based composites. Examples are cassava bagasse, [18] rice husks, [19] corn straw, [20] sugarcane bagasse, [17] and coffee grounds, [21] which can be used with or without chemical and physical treatments. Despite their low cost, one main advantage of using these by-products is the possibility of adding value to agro-industrial waste that, otherwise, could be disposed of with no economical use.…”

Coffee By-Products and Their Suitability for Developing Active Food Packaging Materials

“…When coffee by-products are added into polysaccharide-based formulations, good compatibilization can be achieved without previous treatment or incorporation of any compatibilizer agent into the plastic formulation. The incorporation of crude SCG powder into corn starch-based formulations leads to the development of films with increased tensile strength [ 97 ]. Similarly, the incorporation of crude SCG powder into cellulose-based formulations leads to the development of films with decreased light transmission (high light resistance), with potential for use in vegetable packaging [ 98 ].…”

Thermal, Morphological, and Mechanical Properties of Regular and Waxy Maize Starch Films Reinforced with Cellulose Nanofibers (CNF)

“…There was an increase 1), although it was still higher than the CNF-free films. This reduction is probably due to the aggregation of nanocellulose to a discontinuous and heterogeneous phase, which consequently decreased the films' mechanical properties 4,16,30 .…”

“…Starch is the most widely employed in the elaboration of films, due to its low cost and abundance in nature 4 . Features great capability to form a colorless and transparent polymer matrix, and it is also a heterogeneous material containing different concentrations of amylose and amylopectin 5 .…”