You are here: Home Bioplastics Mirel Structure and Properties

Bioplastics: Mirel Structure and Properties: Page 2 of 6

• Molecular Weight • Thermal Properties • Mechanical Properties • Surface Energy • Gas Barrier Properties • Biodegradability • Stability to hydrolysis • UV Stability

1. Molecular Weight
Metabolix bioplastics are available in molecular weights ranging from around 1,000 to over one million.

2. Thermal Properties
Glass transition temperature (Tg) and melting temperature (Tm) are basic properties of all semicrystalline thermoplastic polymers. The following chart shows the relationship between Tg and Tm for high molecular weight Mirels:

Tg and Tm were obtained using differential scanning calorimetry (DSC) with a heating rate of 10°C per minute; Tm is the peak melting temperature.

Mirel bioplastics are known to be thermally unstable above around 180°C. Attempts to process these materials with high Tms using conventional techniques can result in a progressive reduction in molecular weight and hence mechanical properties. Metabolix has developed techniques and formulations that allow these high Tm bioplastics to be processed with minimal loss in molecular weight.
Metabolix bioplastics have good heat resistance to hot liquids. For example, Mirel coated paper hot cups will handle coffee, soup and other hot liquids.

• Molecular Weight • Thermal Properties • Mechanical Properties • Surface Energy • Gas Barrier Properties • Biodegradability • Stability to hydrolysis • UV Stability