PLA/Coffee Grounds Composites: A Study of Photodegradation and Biodegradation in Soil

Abstract

Biodegradable polymers are an alternative to replacing petroleum‐derived polymers. This work aimed to incorporate coffee grounds (CG) in different contents (5 and 15 wt%) as an accelerator of the biodegradation process to reduce the degradation time of poly (lactic acid) (PLA). The use of this natural source filler can minimize environmental problems, due to its low cost and easy access, since this waste is produced in large quantities. Thus, biodegradable composite can be produced with the use of CG as filler in the PLA matrix. PLA/CG composites are processed using a thermokinetic homogenizer (DRAIS), followed by hot pressing. The samples are subjected to accelerated degradation (ultraviolet radiation – UV) and biodegradation in soil and later are characterized by the percentage of weight loss, visual analysis, morphology by scanning electron microscopy (SEM), thermal analysis (differential scanning calorimetry – DSC) and mechanical properties (Izod impact test). After the biodegradation tests and analysis, it is possible to verify improvements in the mechanical properties of the developed composite, as well as the desired biodegradative effects.

Improving the Mechanical Ductility and Toughness of Injection-molded Polylactide Pieces by the Dual Incorporation of Liquor Waste Derived Spent Coffee Grounds and Oligomers of Lactic Acid

“…al. [60], who also observed an increase in the PLA crystallinity by means of SCGs obtained as a waste from instant coffee preparation. Authors reported an increase in crystallinity of PLA from 9.10 to 12.7% for a 5 wt.% content of SCGs in the green composite.…”

“…Similar than in the case of SCGs, for the samples containing OLA2 and OLA2 mal , cold crystallization also appeared, showing T CC values of 103.7 and 112.9 ºC, respectively. This nding could indicate that these OLAs also impaired crystallization from the melt due to their high solubility and interaction with the PLA molecules [60]. In terms of melting, the slightly lower T m value attained in the OLA2mal-containing sample, which was reduced to 171 ºC, con rms its higher interaction with the PLA matrix, and the imperfection effect provided by this additive on the crystals.…”

“…The addition of SCGs at 20 wt.% further reduced this value signi cantly, down to 18.6 kJ/m 2 , which could be attributed to the presence of SCG aggregates that embrittled the PLA matrix by creating local tensions [59]. In this regard, Da Silva et al [60] also reported a toughness decrease in PLA of 6% for contents of SCGs above 15 wt.%. Impact strength of the PLA and the green composite pieces successfully increased after the addition of both OLAs.…”

Impacts of cellulose nanofibers on the morphological behavior and dynamic mechanical thermal properties of extruded polylactic acid/cellulose nanofibril nanocomposite foam

“…7 The ideal biodegradable polymer must be such that, after use, it is degraded by microorganisms and becomes one of the components of the carbon cycle in nature. 8 Polylactic acid (PLA) is the most developed commercial biodegradable linear aliphatic polyester that can be perfectly degraded into carbon dioxide and water in the natural environment. 9,10 This polymer has been considered in biomedical applications such as tissue engineering, implants, drug delivery systems, and orthopedic devices due to its good tensile strength, as well as its reproducibility and biodegradability.…”

The Effect of Poly (Ethylene glycol) Emulation on the Degradation of PLA/Starch Composites

“…However, applying them into practice often requires the use of special equipment. Biodegradation through the landfill is an easy way by which the degradation rate can be estimated [84]. The soil contains different microorganisms leading to the digestion of polymers followed by converting them into water and CO 2 and subsequently the sample's weight loss.…”