Polymer Degradation.

Polymer degradation is a change in the properties (color, shape, etc) of a polymer or polymer- based product under the influence of one or more environmental factors such as heat, light or chemicals such as acids, alkalies and some salts.
These changes are usually undesirable.

Types of degradation in polymer

1)Photoinduced degradation.

2)Thermal degradation.

3)Chemical degradation.

4)Biological degradation.

Photoinduced degradation

Most polymers can be degraded by photolysis to give lower molecular weight molecules. Electromagnetic waves with energy of visible light or higher, such as ultraviolet light rays and gamma rays are usually involved in such reaction.

Thermal degradation

Chain growth polymers like poly(methyl methacrylate) can be degraded by thermolysis at high temperature to give monomers, oils, gases and water.

Chemical degradation

It is a type of polymer degradation that involves a change of the polymer properties due to a chemical reaction with the polymer surrounding.

Biological degradation

Biological plastics can be biologically degraded by microorganisms to give lower molecular weight molecules.

Examples;

Polyethylene, polypropylene and poly(methyl methacrylate) are sensitive to oxidation and UV radiation, while PVC may discolor at high temperature due to loss of hydrogen chloride gas and become very brittle. PET is sensitive to hydrolysis and attack by strong acid, while polycarbonate depolymerises rapidly when exposed to strong alkalies.

Comments

Determination of molecular weight of polymers by viscosity method.

Determination of molecular weight of polymers by viscosity method. It is a simple method for determining the molecular weight of polymers. Addition of polymers in the solvent increases the viscosity of the solvent, due to introduction of inhomogeneities by the polymers. If η₀ is the viscosity of the solvent and η is the viscosity of the solution at the same temperature, then the relative viscosity is given by Relative viscosity. Specific viscosity: It is defined as the relative increase in viscosity and is given as Specific viscosity. Reduced viscosity: It is defined as the relative increase in viscosity per unit concentration (C) of polymer and is given as Reduced viscosity. Intrinsic viscosity: The reduced viscosity is dependent on concentration (C). If a graph is plotted between reduced viscosity vs concentration then the extraplotation value when C=0 is called intrinsic viscosity. Intrinsic viscosity. Graph of reduced viscosity vs concentr

Polypropylene (PP)

Polypropylene (PP). Polypropylene (PP) is also known as polypropene. Polypropylene is made from the polymerisation of propylene gas in the presence of Zeiglar Natta catalyst or metallocene catalyst. Polypropylene. Thus propene (or propylene) is the monomer of polypropylene. Polypropylene is a highly flammable material. It is sensitive to microbial attacks, such as bacteria and mold. It exhibits excellent resistance to diluted and concentrated acids, alcohols and bases. Polypropylene is used to make lunch boxes, margarine containers, yogurt pots, syrup bottles etc. Disposable syringes is the most common medical application of polypropylene. Polypropylene rope and twine are very strong and moisture resistant very suitable for marine applications. Polypropylene, highly colorfast, is widely used in manufacturing carpets, rugs and mats. Uses of Polypropylene. Questions on polypropylene; Q1) What is polypropylene? Ans) Polypropylene is a polymer of propylen

Difference between organic and inorganic polymers.

Difference between organic and inorganic polymers. Definition Organic polymers are the polymers that essentially contain carbon atom in the backbone. Inorganic polymers are the polymers that have no carbon atom in the backbone. Structure Most organic polymers have simple structures. Almost all inorganic polymers are highly branched and have complex structures. Electrical Conductivity In most of the aqueous solutions, organic polymers are typically poor conductors of electricity and heat. Inorganic polymers in aqueous solutions are good conductors of electricity, this is because they have high ability to ionise and this makes them better conductors. Flammability Organic polymers are flammable whereas inorganic polymers are nonflammable. Effect on nature Organic polymers are environmental friendly as these are biodegradable. Inorganic polymers are not environmental friendly as these are non biodegradable. Examples Organic polymers include polysaccharide

Polymers

Search This Blog