Saturday, August 15, 2015

"Green" plastics-Will Polylactic Acid emerge as a viable choice?

The dominance of synthetic plastics derived from fossil fuels in to day's world is scary as petroleum sources are not going to last for ever and the question as to what then is driving the scientific community feverishly to innovate and come up with viable alternatives based on renewable sources. While cellulose based plastics are manufactured and used for a variety of applications, their functional properties do not come any where near that of synthetic plastics. An yet another problem associated with petroleum based plastics is their near indestructibility and their biodegradability credentials. It takes almost 800 years for most plastics to degrade in nature and disposal in land fills posses enormous dangers to the safety of the environment including water resources. Emergence of poly lactic acid based plastics was thought to be an answer to this problem. Unfortunately these biodegradable plastics cost too high to be commercially viable. The major factor in this cost escalation is the manufacturing technology which appears to be too complex and expensive. Recently a group of scientists from Belgium have come up with a new approach for producing cheaper poly lactic acid base material which if true can be a ground breaking development Read further below.    

"The bioplastic PLA is derived from renewable resources, including the sugar in maize and sugarcane. Fermentation turns thesugar into lactic acid, which in turn is a building block for polylactic acid. PLA degrades after a number of years in certain environments. If it is collected and sorted correctly, it is both industrially compostable and recyclable. In addition, PLA is biocompatible and thus suitable for medical use, for instance in absorbable suture threads. PLA is also one of the few plastics that are suitable for 3D printing. However, polylactic acid is not yet a full alternative for petroleum-based plastics due to its cost. The production process for PLA is expensive because of the intermediary steps. "First, lactic acid is fed into a reactor and converted into a type of pre-plastic under high temperature and in a vacuum. This is an expensive process. The pre-plastic – a low-quality plastic – is then broken down into building blocks for polylactic acid. In other words, you are first producing an inferior plastic before you end up with a high-quality plastic. And even though PLA is considered a green plastic, the various intermediary steps in the production process still require metals and produce waste," said Prof Bert Sels from the Centre for Surface Chemistry and Catalysis. The KU Leuven researchers developed a new technique. Michiel Dusselier, a postdoctoral researcher, explained, "We have applied a petrochemical concept to biomass. We speed up and guide the chemical process in the reactor with a zeolite as a catalyst. Zeolites are porous minerals. By selecting a specific type on the basis of its pore shape, we were able to convert lactic acid directly into the building blocks for PLA without making the larger by-products that do not fit into the zeolite pores. Our new method has several advantages compared to the traditional technique: we produce more polylactic acid with less waste and without using metals. In addition, the production process is cheaper, because we can skip a step."

Whether this development can lead to large scale production of the new plastic materials remains to be seen. At least there is a hope that an alternative option is available on the table. Of course lactic acid production from biomass materials through intervention of microbes can still pose a logistical problem because of competition from fuel industry which also is working on fermentation route for making green fuel. Already there is some criticism regarding diversion of food materials like corn, plant oils and other organic carbon sources for production of alcohol and other fuels to replace fossil fuels. World has to take a holistic view of this critical area and only cooperative endeavors can succeed ultimately.  


No comments: