Drying chart for plastic resins
Although durable, black plastics (especially on vehicle bumpers and trim) have a tendency to dull and fade over time. Fortunately, you can easily restore the plastic’s natural luster. You can make the plastic look like new by applying a coat of olive oil or using a hot air gun on the dulled areas. If this doesn’t work you can use a spray of black paint to bring the plastic back to a shiny shine.
What happens when plastic is heated
The policy states that glass and brittle plastic should not be brought into the plant. If there is force majeure glass or brittle plastic, we must have it controlled through a listing of all glass and brittle plastic in the plant and periodic inspections (on a monthly basis).
But what are brittle plastics? They are those plastics that when they break they spread as if they were glass, and therefore we must take the same care. But many times we do not know which are the brittle plastics that we have in the plant.
Another important fact is about the lights, there are some lamps with Teflon protectors that prevent that if the tube is broken it spreads. I found this interesting link with the information of the lamp, at least to have the reference and look for it in our markets.
Brittle material example
The extreme result that can occur in service is hydrolysis, a chemical reaction with water. Hydrolysis is a slow process at room temperature but can be rapid at high service temperatures. This reaction causes a loss of molecular weight, breakage of molecular chains, loss of molecular weight and therefore loss of polymer properties, especially toughness.
This process is irreversible. Drying the plastic material will not restore the molecular weight or the initial properties. Hydrolyzed parts cannot be shredded and reused because their properties are not recoverable.water exposure of the plastic in the molten state.at melt temperature different reactions of the polymer to water or moisture can occur.plasticization of the mass causes an increase in fluidity. This will be reversible if the polymer is dried and reprocessed.
Hydrolysis occurring at melting temperatures is a rapid and severe process. It is not reversible, there is a loss of molecular weight and properties as well as a drastic reduction in the viscosity of the polymer, thus a substantial increase in flowability. This effect is not reversible. This effect at melting temperature does not require a large amount of water and is a fast process.
Thermal degradation of polymers
There are seven feedstock polymers in use today: polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, polycarbonate and poly(methyl methacrylate) (Plexiglas). These make up 98% of all polymers and plastics present in everyday life. Each of these polymers has its own characteristic degradation modes and resistance to heat, light and chemicals. Polyethylene, polypropylene and poly(methyl methacrylate) are sensitive to oxidation and UV radiation, while PVC can discolor at high temperatures due to the loss of hydrogen chloride, thus becoming brittle. PET is sensitive to hydrolysis and attack by strong acids, while polycarbonate depolymerizes rapidly when exposed to strong alkalis. PET is also sensitive to hydrolysis and attack by strong acids, while polycarbonate depolymerizes rapidly when exposed to strong alkalis. PET is also sensitive to hydrolysis and attack by strong acids.
Increasing chain polymers such as poly(methyl methacrylate) can be degraded by thermolysis at high temperatures to give rise to monomers, oils, gases and water. Degradation takes place by: