Polyester Resin

The invention of plastics and, in general, polymers has led to the development of several such related substances. Plastics in different stiff and solid forms are being used in several different applications, and even as you glance around you will find that you are surrounded by several such substances. In fact the very computer screen from which you happen to be reading this is also made from countless such polymers. A polyester resin is one such substance that has several industrial and non-industrial applications.

About Polyester Resins

It is a thermosetting unsaturated polymer resin, that is formed from the reaction of organic acids and polyhydric alcohols. This kind of compound is used in several domestic and industrial applications. There are several types of polyester which are used and their properties depends upon the acids and alcohols that are used. A resin of polyester is obtained from polymerization of simple molecules of certain compounds, or are secreted by coniferous trees.

Process of Formation
The unsaturated polymer resins are formed from condensation action and are hence called condensation polymers. In such a reaction the by-product of liquids which includes either water or methanol. For the creation of polyester resins, two sets of reactants are chiefly used, namely, polyols which include glycols (e.g.: ethyene glycol) whereas the acid set includes acids such as phthalic acid or maleic acid. The by-product of water is steadily removed till the completion of the reactions. This reaction gives the output of liquid resin. Now, to make the product more usable, it is converted into solid resin, by a cross linking the chains of molecules. This is done by adding free radicals to the compound, which causes the unsaturated bonds to go into a set of chain reactions. This reaction cause them to link with each other, thereby changing the state to solid. In order to generate, or add a free radical, organic peroxides are used which easily get decomposed into free radicals. This compulsion is not a catalyst.

Uses and Applications

There are several domestic and industrial applications, a common example is the Fiberglass Reinforced Plastic (FRP), that you often see in restaurants, kitchens and restrooms. The toner of a laser printer is in fact, also made from polyester resin. A small polyester resin can be used for home repairs as it comes cheap for about $20. Industrial applications include, steel molding compounds, bulk molding compounds and some resin casting.

Now, the actual application is a difficult, part owing to the fact that the polymer gets cured, irreversibly, in an exothermic manner. It means that the resin is heated during the application process and it hardens as it cools down, i.e, it is exothermic in nature. The average, cure time differs as per the consisting polymer compulsion, though the heat required to apply the polyester is about 200 degrees Celsius. The polyester casting resin which requires heat is principally used in industrial applications. The clear polyester resin which have domestic applications are liquid, viscus and combined with a styrene solution to slow down curing and also reduce down viscosity. When the total resin is to be applied, a catalyst and accelerator are added to it in order to start the process. The styrene solution gets decomposed, or isolated, and the resin acts with the catalyst and accelerator, thereby curing and solidifying.

The two competitors to polyester resin are vinyl ester and epoxy resins. While comparing the two, you will realize that the polyester resin has less mechanical properties and strengths, plus the water resistance is also quite less. Apart from these two difficulties, the styrene are a bit harmful to health and environment, in case of constant exposure.