| dc.description.abstract | Thermoplastic materials with biodegradable and sustainable attributes are highly sought after due to the increase in the global plastics waste. Often, filler materials are incorporated into thermoplastics to make them more sustainable and environmentally friendly. Polysaccharides are extensively studied materials as a filler due to their abundance in nature. α-1,3-glucan is a type of polysaccharide that is biodegradable and found in fungi and some bacteria. Aside from its natural origin α-1,3-glucan can also be synthetically produced via enzymatic polymerization which allows for industrial scale production of α-1,3-glucan with controlled structure and molecular weight. It has been reported that α-1,3-glucan shares a few characteristics with cellulose, such as relatively high degree of crystallinity and insolubility in water. Unlike starch and cellulose, which are already commonly used as fillers for thermoplastics, the usage of α-1,3-glucan as a filler in a variety of thermoplastics is lacking. The objective of this research is to investigate the formulation of different thermoplastic composites that utilize α-1,3-glucan.
Three different types of thermoplastics were studied: thermoplastic polyurethane (TPU), poly(butylene adipate-co-terephthalate) (PBAT), and poly(butylene succinate) (PBS). The main goal was to maximize the α-1,3-glucan content in each polymer matrix to fully utilize the sustainability and biodegradability of the α-1,3-glucan. Simultaneously, a wide range of α-1,3-glucan loading levels was tested (ranging from 0 to 80 wt.%) to understand the properties that can be obtained when α-1,3-glucan is used as a filler.
The formulation of the α-1,3-glucan thermoplastic composites involved extrusion, injection moulding, and compression moulding to produce film and bar specimens for analysis. In the case of TPU as the base matrix, different additives such as plasticizers and peroxide were incorporated to investigate their effect on the final properties of the composite samples. With the polyesters, PBAT and PBS, different fillers (cassava starch, microcrystalline cellulose, calcium carbonate) were also used to compare with the α-1,3-glucan counterparts.
Spray drying of the hydrated form of the α-1,3-glucan, known as the wet cake, was investigated with a design of experiment approach to reduce the average particle size. The optimization of the spray drying parameters (sample concentration, feed rate, gas flow rate, drying temperature) was crucial to minimize the average particle size. The preliminary results demonstrated that the reduction of particle size is achievable by adjusting the spray drying parameters.
α-1,3-glucan is a promising material that showed good compatibility with TPU, PBAT, and PBS, since more than 60 wt.% could be added and processed to make specimens. Additional experimentation involving more additives will further improve the quality of the α-1,3-glucan composites. The preliminary spray drying experiment showed promising results to control the particle size distribution. Continued investigation of the spray dried α-1,3-glucan should be conducted to understand the properties as well as optimize the spray drying process. | en |
