Feasibility study of a novel bio-based material through a design thinking approach.

Abstract

Landfilling of non-biodegradable materials is one of the most significant long-term pollution legacies. This practice represents a loss of energy-intensive produced materials alongside with an opportunity for recycling. Environmental and economic concerns arising from the large-scale production and consumption of oil-based materials, have led to an increased interest in developing more sustainable alternatives. Natural fibres (e.g. sisal, jute, flax, etc.) offer a potentially low environmental impact raw material for the packaging industry. Current research in the use of natural fibres in composite materials is reviewed initially in this work. This covers natural fibre properties, surface treatments, composite properties, and manufacturing processes. The rationale for the use of poly(lactic) acid (PLA) as a matrix system is defined. There are studies on the use of Agave tequilana fibres (ATF), but, there is no work reported to date attempting their use as a reinforcement/filler for poly(lactic acid) to replace polystyrene in consumer good applications. In this research, the importance of using a design thinking method in the development of more sustainable materials to be integrated into a circular economy, is established and principles for doing so are drafted. An initial life-cycle approach was used to design a biodegradable ATF and poly(lactic acid) bio-based composite. Experimental work included the development of different grades of fully degradable ATF/PLA bio-based composites using two diverse manufacturing processes; extrusion-press moulding, and film stacking. Bio-based composite properties were modified by exploring several surface treatments. Their resulting bio-based composite properties were investigated to provide enough information about the material behaviour in order to evaluate its potential uses. Mechanical and physical properties (tension, flexural, impact, and moisture) were assessed using standardised tests and methods. The possible routes for recycling or energy recovery of the material to close the material life cycle loop were explored. Despite the by-product character of ATF, it offers a potential low-cost alternative as a reinforcement source for bio-based composites. ATF were observed to have a density of 1.2±0.1 g/cm³ with a tensile strength of 79±38 MPa, and Young’s modulus of 3.3±1.4 GPa. Surface treatments improved ATF tensile properties and interfacial shear strength (IFSS) with PLA. Alkali-treated ATF resulted in a maximum improvement of ~50% in tensile strength and IFSS. According to the results obtained, ATF/PLA bio-based composites with a high fibre content of 60wt% have some properties capable of outperforming those of general purpose polystyrene in several conditions (i.e. ~15% in flexural modulus and ~17% in flexural strength), while in other cases properties did not presented significant improvements (i.e. Young modulus ~3 GPa). The impact of the new ATF/PLA bio-based composite on the current waste management system in Mexico was studied in terms of the “best” economic-environmental-social balanced route at the end-of-life of the material. It is considered that a continuous looping with the least possible loss of carbon and energy is best achieved through biological recycling. Anaerobic digestion of the material was ~14% after 20 days of incubation, with production of ~20 mL CH₄/gVS. Due to the performance presented regarding their economic viability and environmental acceptability within a circular economy, ATF/PLA bio-based composites have the potential to be used in non-structural applications within the consumer goods industry, e.g., packaging, casings for electronic appliances, crates, etc.