Packaging materials biodegradable plastics

The tendency for PLA plasticized with PEG to lose properties with time at ambient temperature is a major obstacle to its application as a biodegradable packaging material. Without plasticizer, PLA is stiff and brittle. Blending with low molecular weight PEG improves elongation at break and softness. The desired mechanical properties are achieved in quenched PLA/PEG blends with 30 wt% PEG However, the blends are not stable at ambient temperature and the attractive mechanical properties are lost over time. Crystallization and phase separation are possible aging processes. 

Compared with more common plastics used as packaging materials, the compound does have some disadvantages, such as a high water vapour permeability and limited heat resistance, losing dimensional stability at about 70°C. It is also substantially more expensive than the high-tonnage polyolefins. Last but not least its biodegradability means that it must be used in applications that will have completed their function within a few months of the manufacture of the polymer compound. 

The most well known application of PHB and poly(3HB-co-3HV) is as substitute for conventional, non-biodegradable plastics used for packaging purposes and derived products [21, 115, 116]. Single-use bottles for shampoos, cosmetics and biodegradable motor-oil have been manufactured from these biopolyesters by common molding techniques. Containers and cups for food products were developed similarly, and bags have been produced from blown films of the material. 

The world biodegradable plastics industry has agreed a set of standards and certification procedures for biodegradable packaging materials, which will continue to encourage growth and possibly deter imitation. 

In 2005, the four leading European biodegradable plastics material suppliers BASF, Nature Works, Novamont and Rodenburg Polymers, have also agreed to submit their packaging materials and products for certification by Din Certco under EN 13432, and label their packaging products with the compostability logo to better inform consumers and retailers. 

In 2004, Office Media (Tokyo) developed a new PLA film exhibiting vastly improved functionality as a packaging material. Through combination with other biodegradable plastics, the film s transparency, flexibility, heat resistance and impact resistance, have been balanced in multiple dimensions, and through adopting two-layer and three-layer structures, gas barrier properties have also been improved. Technology to eliminate the characteristic odour of PLA developed independently by Office Media, have also been applied. 

More recently, biodegradable plastics have been applied in other areas, including packaging and agriculmre (plant containers, mulch films, controlled release of chemical substances, etc.). After hydrolysis of PHAs, the follow-up products can be used as enantiomerically pure starting materials for chiral high price compounds [7-9]. 

This chapter has covered one of the oldest yet most useful of pharmaceutical packaging materials which has survived the onslaught of plastics and, being biodegradable, has considerably contributed to the store of natural materials that can be used for product protection. The chapter has also included sections on security, since papers (in particular) are frequently involved to assist security, a key example being the printing of bar codes—both for security and for efficient stock control and movement tracing. 

Biodegradable plastics based on lactic acid have been available on a small scale for many years. They have been used In applications such as medical implants, but their high price was a deterrent to widespread use in lower value applications such as packaging. However, new technologies for production of lactide monomers greatly lowered costs, making the polymers much more competitive. Generally, the lactic acid is obtained from corn or other biobased materials by a fermentation process, and then chemical synthesis is used to produce the polymer from the lactic acid or lactide monomers. 

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