Multiscale investigation and characterization of nanoparticle reinforced plastics : Toward a circular plastics economy

Abstract

petroleum-based plastics are the result of years of innovation, while bioplastics are still in their infancy, and various options for improvement are considered. These options relate both to the material as such, as well as the processes that are used and need to be tuned to make bioplastics that meet specific requirements. Previously water vapour permeability was discussed as a point of improvement, but in terms of oxygen transfer, bioplastic may already outperform fossil-based plastics; this is highly relevant for the suppression of oxidation reactions that lead to considerable reductions in shelf-life of food products, and food waste. Techniques to alter bioplastic properties?To arrive at a new generation of plastic products that fit within a circular economy, we need to be in a position to fine-tune and alter bioplastic properties at will. Table 1.1 summarizes the pros and cons of potential routes to do so. In light of a transition toward a circular economy, it is important to design materials that are:• biodegradable/compostable and/or recyclable.• meet the required material properties for its envisioned purpose.This can be challenging when considering multi-layered bioplastic films or by blending different bioplastics together given the limited biobased plastics that are currently available.Alternatively, the available biopolymers can be modified (e.g., chemical grafting [27]), or plasticizers and/or micro/nanoparticles can be added [28]. The latter route offers opportunities to create materials with additional functionality through the micro/nanoparticles of choice. Toyota was the first to patent a polymeric nanocomposite (nylon-6 composite 5% nano-clay polyamide [29]), which resulted in a significantly higher tensile strength and resistance to heat distortion. Interestingly, nanocomposites are widely applied in the aviation and automotive industry. Also in food packaging, they have been shown to lead to improved mechanical strength, barrier properties, and altered thermal profile [30][31][32][33][34][35]. Additionally, depending on the selected materials, nanocomposites even possess added functionality related to antioxidant/antimicrobial effects [26,[36][37][38][39]. Despite this wealth of evidence, the potential to use nanoparticles in bioplastic applications is highly underexplored and therefore the focus of this thesis. Adjusting existing processes Reuse, reduce, and recycle of traditional plastics (R9 -R1) Traditional and alternatives co-exist Development alternatives Circular bio-economy (> R0)