Today tremendous progress, both in the technological breakthroughs as well as the marketing issues, has been developed. Although biodegradable plastics are much more expensive than the conventional ones, consumer acceptance on these new products has been increasingly improved due to the public awareness on the environmental problem caused by plastic wastes.
Even though biodegradable plastics may be produced from a petroleum-based resource, most research activities have focused on products made from bio-based materials which is a renewable resource and is considered to be a more environmentally friendly approach. Among bio-based materials from natural resource, starch is one of the most promising raw materials for development of biodegradable plastics due to its availability in large quantity, its relatively low cost and its biodegradability.
Biodegradable plastics from starch
The several approaches for the utilization of starch in the production of biodegradable plastics are following described.
1. Starch as a biodegradable filler for plastics.
The granular starch can directly be mixed with polymer melt under high temperature and pressure in an extruder with its granular structure being preserved; thus, starch granule can act as filler and disperse in the polymer matrix.
2. Thermoplastic starch (TPS)
Thermoplastic material is a polymer that can be softened or melted under the application of heat and pressure and becomes hard solid when being cooled. Most plastics used nowadays are thermoplastics; thus they can be fabricated into films, containers or other shaped articles.
3. Starch foams
Starch foams have been developed as an alternative to polystyrene foam used for manufacturing of loose-fill (cushioning material for filling space around goods within a packing box), foam tray or plate and many other foam products.
4. Starch as a feed stock for fermentation process
Being a pure renewable polymer of glucose, starch has long been used as a major feedstock for the production of a variety of industrial products such as alcohols, aldehydes, esters and acids.
It can be used to produce several types of products including grocery bags, single-use food containers, packaging films, toys and other household items or even the car parts.