Estudo da influência de cargas minerais e amido na biodegradação do PLA

Abstract

Fossile fuel-produced plastics, once consumed and incorrectly discharged into the environment, will end up as short-term non-degradable residues and will contribute to global pollution. For this reason, the use of polymers from biodegradable and renewable sources is seen as an alternative, especially for short-term use products, such as disposable products that might be suitable for composting and thus biodegrated. Many alifathic polyesters possess these desirable properties and, among them the poly (lactic acid) – PLA – is one of the most widely used and advantageous biodegradable polyesters. This work has studied the addition of mineral filler and starch to PLA, to evaluate its influence on biodegrading properties of the polymer. Formulations were subject to mechanical testing of shock and traction, DSC and TGA thermal analysis, fluidity index, organic composite biodegradation up to 120 days, mass loss evaluations, SEM analysis, artificially accelerated aging and viscosity analysis. Results have shown that mineral filler have modified crystallization and did not have any influence on the biodegradation of PLA, but have reduced the polymer`s mechanical properties. The starch has reduced crystallization on the PLA, has enhanced the biodegrading of the composite PLA + starch since it has been observed the composite had high levels of biodegradation over the 120 days period analyzed. This was verified by means of mass loss on the samples, loss of mechanical properties made evident by high brittleness seen upon handling of samples and by scanning electron microscopy. The results of artificial accelerated aging (400h), done just for PLA, have shown a decrease of 40% in mechanical tensile properties.