Ray Cooling, London Press Service

FOOD packaging and other disposable plastic items could soon be composted at home along with organic waste by using a new sugar-based polymer - "green plastic" - thanks to an innovation by UK scientists.

The degradable polymer is made from sugars known as lignocellulosic biomass that come from non-food crops such as fast-growing trees and grasses, or renewable biomass from agricultural or food waste.

It is being developed at Imperial College London by a team of scientists from the Engineering & Physical Sciences Research Council and led by Dr Charlotte Williams.

The search for greener plastics, especially for single-use items such as food packaging, is the subject of significant research worldwide. "It is spurred on not only from an environmental perspective but also for economic and supply reasons," said Dr Williams.

About seven per cent of global oil and gas resources are consumed in plastics manufacture, with production exceeding 150 million tonnes a year. Almost 99 per cent of plastics are formed from fossil fuels.

"Our key breakthrough was in finding a way of using a non-food crop to form a polymer, as there are ethical issues around using food sources in this way," added Dr Williams.

Current biorenewable plastics use crops such as corn or sugar beet.

"For the plastic to be useful it had to be manufactured in large volumes which was technically challenging. It took three-and-a-half years for us to hit a yield of around 80 per cent in a low-energy, low-water-use process," she said.

Biorenewable plastics are materials whose feedstock material (monomer) comes from renewable resources. The leading example is poly(lactic acid) that derives from lactic acid, produced by fermentation of corn or sugar beet.

These biorenewable plastics are different from biopolymers that are naturally occurring polymers such as starch or cellulose (but these are not plastic materials).

This is significant because the leading biorenewable plastic, polylactide, is formed in a high energy process requiring large volumes of water. Furthermore, when it reaches the end of its life, polylactide must be degraded in a high-temperature industrial facility.

In contrast, the oxygen-rich sugars in the new polymer allow it to absorb water and degrade to harmless products - meaning it can be put on the home compost heap and used to feed garden plants and vegetables.

Because this polymer can be produced from cheap materials or waste products it is also economical to make compared with petrochemical-based plastics.

The polymer has a range of properties, laying the field open for a larger number of applications other than biorenewable packaging.

Its degradable properties make it ideal for specialised medical applications such as tissue regeneration, stitches and drug delivery. The polymer has been shown to be non-toxic to cells and can decompose in the body, creating harmless by-products.

The team members - including commercial partner BioCeramic Therapeutics (set up by Professor Molly Stevens and colleagues at Imperial College London) - are investigating ways of using the material as artificial scaffolds for tissue regeneration. They are also looking at exploiting the degradable properties of the material to release drugs into the body in a controlled way.

"The development of the material is very promising and I am optimistic that the technology could be in use within two to five years," said Dr Williams who is working with a number of commercial partners and is keen to engage others interested in the material.

The polymer was discovered and developed by Dr Min Tang and Dr Anita Haider in their doctoral research. Dr Tang continues to develop the materials.

The Engineering & Physical Sciences Research Council is the main UK agency for funding research and training in its title's fields, investing more than 850 million pounds a year in a range of subjects, from mathematics to materials science, and from information technology to structural engineering.