Investigation of the Mechanical Strength of Cell-plastics Fabricated Using Unicellular Green Algal Cells and Varying Weight Ratios of Biodegradable Polybutylene Succinate

Akihito Nakanishi,Marina Watanabe,Yuri Sakihama,Kohei Iritani

doi:10.11648/j.ijmb.20200504.11

Abstract

Petroleum-derived plastics are currently indispensable; however, they are non-recyclable and exhaustible. Despite global progress in the research and development for biodegradable green plastics using recyclable resources, green plastics are unable to replace petroleum-derived plastics so far because of the costs involved in the extraction and purification processes. Due to the increasing demand for the development of innovative green plastics, cell-plastic composed of the green alga Chlamydomonas reinhardtii as an ingredient and biodegradable compounds as fillers was proposed as a novel green plastic. For a carbon-recycling system in the future, C. reinhardtii is advantageous due to higher growth activity using CO2 gas in atmosphere compared to other terrestrial plants. In addition, the rigidity of its cell wall would prevent the reduction of a mechanical strength of the cell-plastics. Green plastics made of organic polymers are expensive because of high producing cost. On the other hand, the plastics made of green algae, instead of organic polymers, would be expected reducing the price. Thus, the purpose of this study was to clarify whether the cell-plastics produced by substituting organic polymers with algal cells could perform mechanical and physical properties similar to existing plastics products. As a filler for cell-plastics, biodegradable polybutylene succinate (PBS), which form a self-standing film, was chosen in this study. PBS cell-plastics were examined for their following mechanical and physical properties: Young's modulus, tensile strength, thermal analysis, and surface hydrophilicity. PBS cell-plastic (1:1) composed of 50% PBS (w/w) exhibited the potential to replace petroleum-derived plastics such as low-density polyethylene and polyvinyl chloride. This study introduces the practical possibility of PBS cell-plastics as green plastics.

Highlights

Petroleum-derived plastics such as polyethylene and polyvinyl chloride (PVC) are essential in the current society because of their low production cost, simple processing, and easy endowing strength for various purposes [1]
Glycerol could be correlatedly connected to hydrophilic cells, the use of glycerol decreased the mechanical strength of the cell-plastics compared to the strength of ordinal petroleum-derived plastics since the cells were connected with a weak bond
Since the C. reinhardtii cells used in this study have many hydroxy groups on their cell walls, it was theorized that hydrogen bonding could occur between the hydroxy groups on the cell walls and the carbonyl groups on polybutylene succinate (PBS), resulting in the formation of a unified PBS cell-plastic

Summary

Introduction

Petroleum-derived plastics such as polyethylene and polyvinyl chloride (PVC) are essential in the current society because of their low production cost, simple processing, and easy endowing strength for various purposes [1]. These cells are weakly bound with noncovalent bonds, so the macro molding would not be inhibited even while using these rigid cells as the components; its mechanical strength as a plastic material would be diminished To overcome this issue, glycerol and bovine serum albumin were used as intercellular fillers to connect each cell and a thin organic layer was applied as a reinforcer to coat the laminate structures of the cell-layers, resulting in the formation of a self-supporting film of cell-plastic. Cell-plastic had the potential to be the new green plastic, it was problematic owing to its time-consuming and complicated process since its production required almost complete water removal and layer laminations These problems could be attributable to the intercellular filler glycerol that prevented the drying of the cell-plastic film due to its hydrophilic nature. Extraction and purification costs of PBS are higher than that of preparation of C. reinhardtii cells

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