Back in the seventies, I was given a couple of golf tees made from polyhydroxybutyrate (PHB), a plastic produced by microorganisms under controlled conditions of physiological stress. It is similar in appearance to polypropylene and as far as the eye could tell, these golf tees were ordinary plastic tees. But because they were made of PHB, they were biodegradable. Tees lost in the rough would slowly rot away.
I tried leaving them in sewage sludge and if I remember rightly, within a week or so they had turned brown and the smooth surface had begun to degrade. Wikipedia lists is properties as:-
- Water insoluble and relatively resistant to hydrolytic degradation. This differentiates PHB from most other currently available biodegradable plastics, which are either water soluble or moisture sensitive.
- Good oxygen permeability.
- Good ultra-violet resistance but poor resistance to acids and bases.
- Soluble in chloroform and other chlorinated hydrocarbons.
- Biocompatible and hence is suitable for medical applications.
- Melting point 175°C., and glass transition temperature 2°C.
- Tensile strength 40 MPa, close to that of polypropylene.
- Sinks in water (while polypropylene floats), facilitating its anaerobic biodegradation in sediments.
- Less 'sticky' when melted, making it a potentially good material for clothing in the future
So these materials can be made and markets for them may be developed. Oil is not the only possible source of plastics - merely the cheapest.
Until someone decides to subsidize PHB of course, which may already be going on via carbon credits. In the seventies we knew those golf tees were unlikely to be anything more than curiosities - possibilities worth investigating as university research projects, but with only a marginal chance of commercial success.
But in the world as it is now - who knows?