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For lack of nitrogen and phosphorus they produce a kilogram of PHA per three kilograms of sugar. The simplest and most commonly occurring form of PHA is the fermentative production of poly-beta-hydroxybutyrate [poly(3-hydroxybutyrate), P(3HB)], which consists of 1000 to 30000 hydroxy fatty acid monomers.
2007: Metabolix inc. market tests its first 100% biodegradable plastic called Mirel, made from corn sugar fermentation and genetically engineered bacteria. (Digregorio 2009) [ 100 ] 2012: A bioplastic is developed from seaweed proving to be one of the most environmentally friendly bioplastics based on research published in the journal of ...
PHB-derived plastics are attractive because they are compostable and derived from renewables and are bio-degradable. ICI had developed the material to pilot plant stage in the 1980s, but interest faded when it became clear that the cost of material was too high, and its properties could not match those of polypropylene .
A plastic is considered a bioplastic if it was produced partly or wholly with biologically sourced polymers. A plastic is considered biodegradable if it can degrade into water, carbon dioxide, and biomass in a given time frame (dependent on different standards). Thus, the terms are not synonymous. Not all bioplastics are biodegradable. [44]
Biomass comes from crops such as sugar beet, potatoes, or wheat: when used to produce biopolymers, these are classified as non food crops. These can be converted in the following pathways: Sugar beet > Glyconic acid > Polyglyconic acid Starch > (fermentation) > Lactic acid > Polylactic acid (PLA)
The physical properties [31] of polymer strongly depend on the length (or equivalently, the molecular weight) of the polymer chain. [32] One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. [33]
The degradation process is erosive and appears to take place in two steps during which the polymer is converted back to its monomer glycolic acid: first water diffuses into the amorphous (non-crystalline) regions of the polymer matrix, cleaving the ester bonds; the second step starts after the amorphous regions have been eroded, leaving the ...
Plastics per se have low toxicity due to their insolubility in water and because they have a large molecular weight. They are biochemically inert. Additives in plastic products can be more problemative. [45] For example, plasticizers like adipates and phthalates are often added to brittle plastics like PVC to make them pliable. Traces of these ...