Sep 15, 2024 10:12 PM
https://montrealgazette.com/opinion/colu...d-problems
EXCERPTS: . . . Obviously, recycling, reusing and cutting down on non-essential uses of plastics are desirable goals. But we also need to discover ways to source the raw materials from renewable sources and develop plastics that degrade into harmless substances in the environment. This is where bioplastics come into the picture.
“Bio” means life, so bioplastics are plastics that are at least partially made from raw materials derived from living organisms, or are biodegradable. Biodegradable means that they can be broken down by bacteria, fungi or microbes into simple compounds such as carbon dioxide and water that can be reabsorbed by the environment, ideally without causing any pollution.
Bioplastics are classified according to either their origin or their biodegradability. [...] At this point, only about one per cent of all the plastics produced are bioplastics — hardly an amount that has a great impact.
Microbes can not only break plastics down, they can also produce them. Bacteria and fungi are like little chemical factories that produce special proteins called enzymes that catalyze chemical reactions [...] PLA is the most commonly used bioplastic, suitable for disposable cutlery and compost bags. It is biodegradable, but only in an industrial composting facility. It will not biodegrade in a home compost pile. In the anaerobic conditions of a landfill, it will eventually biodegrade, but the product then is methane, a potent greenhouse gas.
The second-most widely used bioplastic is PHA, which stands for polyhydroxyalkanoate. PHA is actually a family of polyesters that are naturally produced by some bacteria. For example, the soil bacterium Cupriavidus necator can produce a variety of PHAs depending on the nutrient it is fed, which can be methane, starches or fats from plants or animals.
The great advantage of PHAs is that they will biodegrade in ambient environments, even the ocean. This makes them suitable for single-use products like food packaging, straws and cutlery. Their downside is cost: PHAs are about 10 times more expensive than PLAs.
Some clever chemistry has led to another biodegradable plastic that, while not as readily biodegradable as PHAs, has physical properties that come close to matching those of conventional plastics. It goes by the tongue-twisting name of polybutylene adipate terephthalate, or PBAT...
[...] There is no question that there is some interesting chemistry in the quest for better bioplastics, but these materials will not solve the world’s plastic problem... (MORE - missing details)
EXCERPTS: . . . Obviously, recycling, reusing and cutting down on non-essential uses of plastics are desirable goals. But we also need to discover ways to source the raw materials from renewable sources and develop plastics that degrade into harmless substances in the environment. This is where bioplastics come into the picture.
“Bio” means life, so bioplastics are plastics that are at least partially made from raw materials derived from living organisms, or are biodegradable. Biodegradable means that they can be broken down by bacteria, fungi or microbes into simple compounds such as carbon dioxide and water that can be reabsorbed by the environment, ideally without causing any pollution.
Bioplastics are classified according to either their origin or their biodegradability. [...] At this point, only about one per cent of all the plastics produced are bioplastics — hardly an amount that has a great impact.
Microbes can not only break plastics down, they can also produce them. Bacteria and fungi are like little chemical factories that produce special proteins called enzymes that catalyze chemical reactions [...] PLA is the most commonly used bioplastic, suitable for disposable cutlery and compost bags. It is biodegradable, but only in an industrial composting facility. It will not biodegrade in a home compost pile. In the anaerobic conditions of a landfill, it will eventually biodegrade, but the product then is methane, a potent greenhouse gas.
The second-most widely used bioplastic is PHA, which stands for polyhydroxyalkanoate. PHA is actually a family of polyesters that are naturally produced by some bacteria. For example, the soil bacterium Cupriavidus necator can produce a variety of PHAs depending on the nutrient it is fed, which can be methane, starches or fats from plants or animals.
The great advantage of PHAs is that they will biodegrade in ambient environments, even the ocean. This makes them suitable for single-use products like food packaging, straws and cutlery. Their downside is cost: PHAs are about 10 times more expensive than PLAs.
Some clever chemistry has led to another biodegradable plastic that, while not as readily biodegradable as PHAs, has physical properties that come close to matching those of conventional plastics. It goes by the tongue-twisting name of polybutylene adipate terephthalate, or PBAT...
[...] There is no question that there is some interesting chemistry in the quest for better bioplastics, but these materials will not solve the world’s plastic problem... (MORE - missing details)