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Abstract

This study explores semi-solid bioplastics' fabrication based on alginate polymers with added glycerine as plasticiser creating flexibility. Organic waste was used as a filler and avoid material shrinkage. Exploratory, observational and experimental methods and a literature review were used within a qualitative and quantitative methodology to reach the desired results. The researched material was documented through an open-source FabLab platform and shared with a community of researchers and future designers who want to design innovative and environmentally friendly materials, which can replace synthetic plastics. Fifteen different bio-based materials resulted from this experiment, which can have variable applications. Results show that different fillers added to sodium alginate and glycerine present ample opportunities for sustainable bio-ceramics, bio-composites and bio-plastics.

 

Keywords

Bio-based materials, alginate bio-composites, open-source, 3D handheld printing

 

Introduction

Once an excellent solution to the design of all kinds of products, plastic has become one of the most urgent problems to tackle currently. The material created to last is ironically also used mostly for single-use purposes. Thirty-three per cent of all plastic – water bottles, straws and, most recently, unnecessary plastic packaging from e-commerce giants such as Amazon – is used once and thrown away (Plastic Pollution Coalition, n.d.). Plastic, however, will not biodegrade but breaks down into microscopic particles, contaminating the waters, threatening wildlife, poisoning food chains, affecting human health, the environment and costing billions to halt (Ibid.). There is an urgent need for plastic alternatives within the design industry (Lockton et al., 2013).

Bio-based composites are combinations of two or more materials from a natural source: a reinforcing (e.g. fibres, particles) and a matrix (e.g. polymer, metal or ceramic). According to Saxena et al., soon, biodegradable polymers are expected to replace synthetics. Natural fibre composites are easily available, renewable, low-cost, lightweight and with specific strengths and stiffnesses. Bio-composites have received much commercial success in the semi-structural as well as structural applications (Saxena et al., 2011, p. 124). Organic-based bio-plastic uses natural polymers from renewal biomass sources through polymerisation (Kipngetich & Hillary, 2012). According to Dicker et al., green composites can be defined as bio-derived polymers reinforced with natural fibres; these might take on different properties and applications.

One attribute of green composites "is their tendency to absorb water and degrade; a complementary application attribute would be limited exposure to moisture" (Dicker et al., 2013). Nevertheless, this material research study focused on hydrophobic properties to provide material longevity, resilience, and applicability in 3D projects, such as pots, reusable packaging, tableware, and furniture (Sauerwein, 2020). Therefore, waterproof seaweed-based polymer (i.e. sodium alginate) was chosen as a base, considering future studies with easy access to the raw material (both in Portugal and the Netherlands). Seaweed in European, North Atlantic and Mediterranean environments are used for varied purposes, from food to bio-fertilisers. Depending on the size, algae are named macroalgae or seaweed (i.e. benthic) or microalgae (i.e. planktonic), and divided into three taxonomic groups: Chlorophyta (green algae), Rhodophyta (red algae) and Phaeophyceae (brown algae)(Pereira, 2015, p. 187).

Algae neutralise greenhouse gas emissions from factories, remediate wastewater and Co2 emissions as a nutrient source (Ferreira, 2014), and have a high growth rate (Kipngetich & Hillary, 2012, p. 11). Marine algae constitute a great source of natural polysaccharide, providing four groups of phycolloids (e.g. seaweed gum): the Agars, the Carrageenans and the Gelans from red seaweed and the Algins derived from major brown seaweed (Rinaudo, 2014). Brown algae contain a large amount of alginate, providing for varied applications, for instance, biomedical materials, packaging, food, the paper industry, textiles and wound dressing.

Sodium alginate is the most common salt of alginate and, when crosslinked with calcium chloride, generates strong gels. These gels can be used and applied with different methods, such as solvent casting, extrusion and spraying. Their mechanical properties depend on the plasticisers that improve flexibility, reduce brittleness and improve impact resistance (Senturk Parreidt et al., 2018).

 

Objectives

Exploring and documenting properties of specific bio-based materials for usage in a handheld extruder. This extruder was assembled based on an existing open-source extruder model and adapted for utilisation with the preferred and suitable semi-solid bio-plastics.

 

Methodology

This project was developed during one week for the 2020 Fabricademy assignment 'Open-source hardware: from fibres to textile', Textile Lab Amsterdam. Open-source hardware was used to create a handheld 3D printer, and the aim was to extrude semi-solid bio-based materials that can replace synthetic plastics (Jongenburger, 2013).

A mixed-method approach was used, and the initial recipes were retrieved through an open-source literature review. From there, exploratory research was executed, attempting to create semi-solid bio-plastics that were fluid enough to be extruded with a handheld extruder. By experimenting with increasing amounts of solidifiers, such as shell sand, eggshells and ground coffee, a total of fifteen different bio-plastics were created and tested for potential extrusion. In addition, observational research methods were used to decide which materials would be suited for which purpose. As such, multidisciplinary research methods proved relevant to reach the desired results.

 

Results and Discussion

The experimental recipes started from provided literature references (Kochhar, 2018)(Ferlatte, 2019) (Bolumburu, 2018). These were adjusted for appropriate syringe usage with an electric handheld extruder for 3D printing to create semi-solid bio-plastics suitable for replacing synthetic plastics.

The research was developed for educational purposes within the design field. Bio-based composites were analysed by direct observation through: a) the suitability for handheld extrusion; b) the appropriate solidity or liquidity; c) the adaptation to the nozzle in use; d) their properties. Materials were photographed in two distinct phases: wet and cured and after the material dried, to observe shrinking and final characteristics (table 1.). The results lead to a variety of bio-plastics that can be used for different purposes.

Conclusion

High calcium carbonate value on Eggshells waste gives particular resilience and physical attributes, of worth, for bio-ceramic composites. In seashore countries (e.g. Portugal, Netherlands), shell sand reveal opportunities for treasuring waste as sustainable materials.

Coffee grains bio-composite revealed plasticity and rubber appearance, relevant for vegan leathers or packaging. These have potential interest for future studies: collecting waste on cities coffee shops to easily scale-up bio-based products.

In conclusion, using natural waste for bio-composites allows for easy reproduction, testing and improving results. Using open-source recipes and literature promotes worldwide collaborative learning and research towards a sustainable approach (e.g. social and economic). Future experiments are needed to collect more data about material resistance, shrinking, waterproof properties and weight.

 

Acknowledges

The authors gratefully acknowledge TextileLab Amsterdam - Fabricademy collaboration and FCT - Foundation for Science and Technology, Portugal.