Better Bioplastics  

I remain fairly enthusiastic about bioplastic as a long term substitute for petrochemical based plastics - TransMaterial has a post about a recyclable bioplastic which remembers its shape.

Unlike conventional petroleum-based plastics, polylactic acid (PLA) plastic is mass produced by chemical synthesis using raw materials derived from corn. The production of PLA contributes less CO2 to the atmosphere than that of conventional plastics and offers superior biodegradability after disposal. Because PLA plastics are often more expensive than conventional ones, researchers are developing ways to add value to PLA plastics.

NEC Corporation’s Dr. Masatoshi Iji has developed a PLA-based bioplastic with shape memory and recyclability. The polymer deforms with heat and external pressure and remains in that altered shape when cooled. Once reheated, the plastic returns to its original shape. Shape memory conventionally requires plastics with a cross-linked structure, which prohibits melting and thus recycling. However, NEC’s shape-memory polymer utilizes a characteristic called thermo-reversible cross-linking. The material can be deformed and restored to its original shape by heating at the temperature of a hairdryer (approx. 140°F [60°C]), but if heated to a typical molding temperature 320°F (160°C) the cross-linked structure dissociates, causing the material to melt and enabling easy recyclability.

For regions like the European Union, whose consumers are adverse to anything genetically modified even if it's their plastic cutlery, US maize-based bioplastics aren't very tempting.

But a ready market of more than 2 million metric tonnes of bioplastic in Europe is waiting for the alternative.

This week, an Italian joint venture between sugarbeet growers in Bologna and bioplastics manufacturers Bio On have had their new PHA product certified as entirely biodegradable in water.

The PHA made from beet replaces many hard plastics like PVC and polypropylene for use in everything from bottles and packaging to furniture and electronics.

PLA also replaces polypropylene and polyethylene for foils, plastic bags, and other kinds of packaging. Bio-based ethylene that is used to create PP and PE replacements is becoming big business now in Brazil thanks to the joint venture between Dow Chemical and CrystalSev last year.

By using ethanol as a base, they will produce 350,000 tonnes of PE every year from 2011. DuPont, along with Genencor, have come up with technology to produce a new polymer from maize sugar - that could easily be done with cane or beet sugar - that can substitute petroleum products used in things like auto paints.

PE from cane has its green credentials too. Brazilian chemicals group Braskem claims that using its technology to create PE from sugarcane ethanol to produce one tonne of polyethylene actually removes from the environment 2.5 tonnes of carbon dioxide while the traditional petrochemical route results in emissions of close to 3.5 tonnes.

Braksem announced its new technology around the same time Dow married CrystalSev on the bioplastic deal. Braskem's polymer-high-density polyethylene, one of the most widely used resins in flexible packaging, is the result of a research and development project in which only USD$5 million was invested.

It expects to produce 200,000 tonnes per year from the end of 2009.

But these new technologies go even further. Researchers at New York's Polytechnic University have discovered a plant-based bioplastic that degrades directly into biodiesel after it is used.

No need for recycling, or messy technical and expensive processes, and the fuel doesn't even need to be purified before it can go straight into the tank.

Supposedly the US government is looking into the new product as a way to reduce the massive amounts of waste left behind when the military is in the field while securing additional sources of fuel for their vehicles at the same time.