By What causes degradation of polymers?
Polymer degradation can be caused by heat (thermal degradation), light (photodegradation), ionizing radiation (radio degradation), mechanical action, or by fungi, bacteria, yeasts, algae, and their enzymes (biodegradation).
What are the types of polymer degradation?
The types of polymer degradation can be divided into three general categories: chain depolymerisation, random scission and substituent reactions.
What does hydrolytic degradation mean?
Hydrolytic Degradation: This process occurs in polymers that are watersensitive active groups, especially those that take a lot of moisture. Polymers that have an ability for hydrolytic destruction usually have heteroatoms in the main or side chain.
What is mechanical degradation of polymer?
Mechanical degradation describes the breakdown of molecules in the high flow rate region close to a well as a result of high mechanical stresses on the macromolecules. This short-term effect is important only in the reservoir near the wellbore (and also in some of the polymer handling equipment, in chokes, and so on).
What are the types of degradation?
Soil Degradation
- Types of soil degradation. Soil degradation can be classified into four main types of degradation: water erosion, wind erosion, chemical deterioration and physical deterioration.
- Water erosion.
- Wind erosion.
- Chemical deterioration.
- Physical deterioration.
- Human causes of erosion.
- Control of erosion.
- Conclusion.
What is meant by polymer degradation?
Polymer degradation is a change in the properties of the polymer, such tensile strength, color, shape, and molecular weight, or of a polymer-based product under the influence of one or more environmental factors, such as heat, light, chemicals, or any other applied force.
What happens during polymer degradation?
Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. The major chemical changes are oxidation and chain scission, leading to a reduction in the molecular weight and degree of polymerization of the polymer.
How can we prevent drug degradation?
Use of surfactant-based systems such as micelles can reduce the hydrolysis of hydrophobic drugs. Alternatively, preparing a suspension reduces the amount of drug in solution and hence may increase stability. A lyophilized product will remove water and significantly reduce the rate of hydrolysis.
Are polymers waterproof?
The modern airy waterproof fabrics are made with two layers of polymers with different properties: a first layer of a micro-porous polymer that is hydrophobic, i.e. it repels water, and a layer of polyurethane, turned inwards, closer to the skin and which is hydrophilic (i.e. it attracts water) and absorbs the …
How do polymers fail?
Failure in polymer components can occur at relatively low stress levels, far below the tensile strength because of four major reasons: long term stress or creep rupture, cyclic stresses or fatigue, the presence of structural flaws and stress-cracking agents.
What is called degradation?
Degradation is the act of lowering something or someone to a less respected state. A president resigning from office is a degradation. It’s also a downcast state. Once the president has resigned, he might feel degradation. The noun degradation is related to the verb degrade, which comes from the Latin degradare.
What are two types of environmental degradation?
There are mainly three different types of environmental degradation. They are land degradation (also called soil degradation), water degradation, and air degradation. The degradation of these three environments impacts the global climate and living conditions to a great extent.
What causes the degradation of a polymer chain?
Degradation is often due to a change in the chemical and/or physical structure of the polymer chain, which in turn leads to a decrease in the molecular weight of the polymer. These changes may be undesirable, such as changes during use, or desirable, as in biodegradation or deliberately lowering the molecular weight of a polymer.
How is triclocarban similar to carbanilide in structure?
Triclocarban, 3- (4-chlorophenyl)-1- (3,4-dichlorophenyl)urea, is a white powder that is insoluble in water. While triclocarban has two chlorinated phenyl rings, it is structurally similar to carbanilide compounds often found in pesticides (such as diuron) and some drugs.
What kind of carcinogens are produced by triclocarban?
When triclocarban is manufactured, 139 toxic, carcinogenic byproducts, such as 4-chloroaniline and 3,4-dichloroaniline, are released. More of these carcinogens can be released upon chemical, physical and biological attack of triclocarban. The duration of triclocarban chemical in personal product use is relatively short.
Which is the most serious mechanism to degrade plastics?
The majority of polymers are susceptible to thermooxidation aging in the open environment and it’s considered the most serious mechanism to degrade plastics that has not been engineered to intentionally degrade. The influence of thermooxidative degradation on polymers is depending on their chemical structure.