Skip to main content

Coatings.

Coatings.

  • Painting and coating are interchangeable terms but basically painting is done for decoration and coating is done for protection.
  • The polymeric coatings are applied to elastomers, metals, ceramics and other polymeric materials.
  • Examples of polymeric coatings are natural and synthetic rubbers, urethanes, PVC, phenolic resins, acrylics, silicone and nitrocellulose.
  • They are the polymers which provide surface that are both hydrophobic and oleophobic and make substances like adhesives and food ingredients non sticky.
  • They are FDA approved.
  • Polymeric coating are made from polymeric materials and are applied to different substrates using different techniques such as dispersion/ extrusion coating and solution application.
  • These coating are done for corrosion resistance.
  • They must adhere well to substrate and must not degrade by heat, moisture and chemicals.
  • Acrylics and alkyds are used as corrosion resistant coating for farm equipment and industrial products.
  • Polyurethanes are used as abrasion resistant coating for aeroplanes and motorcycle parts.
  • Nylon-11 coating is used for attractive appearance, protection from chemicals and  abrasion.

Comments

Post a Comment

Popular posts from this blog

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...
Post a Comment
Read more

Determination of molecular weight by osmotic pressure method

Determination of molecular weight by osmotic pressure method. Osmotic pressure method is also called membrane osmometry. This method is widely used to determine the number average molecular weight of polymers. This method is based on the phenomenon of osmosis. If a pure solvent is separated from a solution through a semipermeable membrane, due to concentration (chemical potential) difference between the solvent and solution, the solvent will flow into the solution through semipermeable membrane. The pressure applied on the solution to completely stop the flow of solvent into it through semipermeable membrane is called osmotic pressure. The theory of osmotic pressure also applies to a solution of polymers. Ordinary solution obeys Van't Hoff equation i.e π=cRT/M Where π is osmotic pressure, c  is concentration in mass per unit volume, R is gas constant, T is temperature and M is molar mass. The polymer solution are non ideal. Taking into account their deviation and us...
Post a Comment
Read more

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...
Post a Comment
Read more