Biodegradable plastics

A challenge of great responsibility for the petrochemical industry.

Research into biodegradable plastics and traditional plastic varieties that could be made degradable has received more and more emphasis in recent years. Below you will find a summary of results already achieved by TVK and  MOL Group in this technical area, and of their future plans.

Global plastics production has increased to enormous levels in recent decades. According to  latest statistics, the increase between 2002 and 2006 was more than 20%, from 200 million to 245 million tons of which use of thermoplastic materials increased from 152 million to 197 million tons and is forecasted to reach 250 million tons by 2010.

Swift degradation is the goal

The life span and usage period of products in certain industry sectors (e.g. packaging and agriculture) are limited and, in most cases, do not exceed more than a few weeks or months. In such cases, it would naturally be very advantageous if, at the end of their lifecycles, such products could degrade due to natural external causes at their locations of use, or at waste disposal sites or other designated locations. Of products with limited or controlled life cycles, waste collection bags, bottles and barrels, disposable products used by fast food chains (cups, trays and cutlery) as well as different types plastic tank and agricultural foil are the most significant.

 

Reduction of impact on the environmental

MOL Group Petrochemical Division plants in Tiszaújváros and Bratislava produced a total of more than 1.2 million tons of polymer products in 2007, most of which were used by the packaging industry, as is the case internationally. Most of these packaging materials have short lifetimes (e.g. packaging foils and bags) and after the products they contain such as various foodstuffs are removed, they become waste. To reduce impact on the environment, the specific direction research is taking is the modification of traditional plastic products so they become biodegradable.

Development with Norwegian assistance

TVK first started to examine this area on the initiative of the Norwegian company Nor-X Industry AS which produces special masterbatches (granulates that already contain a kind of additive in large quantity to simplify future processing) that help the degradation of different plastic products. The primary goal, jointly agreed in 2007, was to develop masterbatches with optimal composition for polypropylene. The main active substance in the masterbatches is iron stearate which is blended with various plastics [e.g. polypropylene (PP) or linear low density polyethylene (LLDPE)] to produce the masterbatches. These masterbatches were then added to one of TVK's polypropylene products in varying concentrations, and then the properties and weather resistance of films made from them were tested.

Under UV radiation, the degradation process started at the expected rate in samples containing the additive, but not faster if light were not present (ageing in oven) , than in  samples without additive. It is therefore expected that degradation will only commence when products such as the packaging materials mentioned above enter the environment as waste and are then exposed to sunlight.

Several series of experiments are planned for the near future in which the composition of the master mixture applied will be further optimised and tested in more widely varying concentrations, mainly towards to the direction of lower ratios. .

In 2008, to get a more accurate picture of the composition and mechanism of these additives, a joint development project has been set up with the Organic Chemistry Department at Pannon University (Veszprém, Hungary), which has in-depth experience in chemical processes initiated by metallic catalysts.