Thermoplastic-based blend packaging applications

The major classes of biopolymer, starch and starch blends, polylactic acid (PLA) and aliphatic-aromatic co-polyesters, are now being used in a wide variety of niche applications, particularly for manufacture of rigid and flexible packaging, bags and sacks and foodservice products. However, market volumes for biopolymers remain extremely low compared with standard petrochemical-based plastics. For example, biopolymer consumption accounted for just 0.14% of total thermoplastics consumption in Western Europe for 2005. 

While biodegradable polymers may be similar to petrochemical-based thermoplastics in terms of their structure, their chemical structure imbues them with technical properties that make them perform in different ways. For example, starch blends can produce film with better moisture barrier protection and higher clarity than some conventional plastics. PLA has a high water vapour transmission rate, which is beneficial for fresh food applications where it is important that the water vapour escapes quickly from the packaging. PLA also reduces fogging on the lid of the packaging. 

Polylactide has high potential in agricultural applications such as mulch films either in pure form or blended with other polymers such as thermoplastic starch. In addition, polylactide is used in compostable yard bags and dog poop bags. Lactic acid based hot-melt adhesives have also been developed (90). Foamed PLA could be used as structural protective foams, loose-fill packaging and insulation material as an alternative for expanded polystyrene (EPS). While packaging is currently the high volume application... 

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