840: Starch-based composites prepared by injection moulding: effect of formulation composition on the final properties

Starch-based composites prepared by injection moulding: effect of formulation composition on the final properties

Susana C. Pinto^a, Vasco G. Lopes^b, Dmitry V. Evtyugin^a

^aCICECO, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal

^bThinkPack – Lab & Packaging Center, Lda, 3500-092 Viseu, Portugal

 scpinto@ua.pt

 Abstract

The transition from synthetic plastic-based packaging to biodegradable alternatives is advancing quickly driven by the stringent plastic-related regulations.¹ The utilization of natural resources, industrial by-products, and wastes, combined with cleaner processing techniques, is being prioritized, contributing to sustainability and circular economy.² Over the last decade, starch as a renewable thermoplastic material has garnered significant interest from the packaging industry as a substitute of the synthetic ones. Regarding the starch-based composites, the high hydrophilicity and weak mechanical response offered by these products limits its wide application. To address these limitations, several additives, such as fibrous or inorganic filles are usually added.³ In this study, we prepared four-component formulations including starch as the main matrix, different cellulosic pulps from the pulp industry as the reinforcing element, kaolin as the inorganic filler, and water as the plasticizing and blowing agent. The mixtures of different compositions were processed using injection moulding to produce lightweight composites, diverging from the more commonly employed method of thermoforming. This study aimed to evaluate the influence of each aforementioned formulation components on the microstructure, mechanical properties, and dimensional stability of the final products. The results showed that water plays a crucial role on the processability and microstructure of the foamed materials. The injection moulding of formulations is very difficult for water contents below 40 wt% or above 60 wt%. Fibrous pulp acts positively as a mechanical reinforcement component of the composite, being applied up to 10-15% wt% and causing procedural difficulties when applied at levels higher than 15% wt%.

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