Polymerization

Most of the advantages and disadvantages depending on the size of the polymer structure of individual polymer molecules, the shape and size of polymers and how they are formed. Characteristics of polymer molecules is determined by the size, features that set it apart from other organic chemical composition. Polymers are long chains of molecules, also called mocromolecules or giant molecules, which is formed by polymerization, in other words with the interrelated and crosslinking of different monomers. Monomer is a block up the foundation of a polymer. Mer derived from the Greek word meros meaning part, indicating the smallest unit.

Mer or polymer means a lot of units, generally is the repetition of hundreds or thousands of times a chain-like structures. Most of the monomer is an organic material in which carbon atoms are combined in a covalent bond with other atoms, such as Hydrogen, Oxygen, Nitrogen, Florin, chlorine, silicon and sulfur.

Macromolecules to form bonds of each molecule of thermoplastic material done in three ways, namely:

a. Polymerization:

Bringing together some similar molecules to form large molecules Polymerisate. Monomers in the polymer can be bound in repeating units that extend and enlarge the molecules with a chemical reaction known as polymerization reactions. Although many variations, the two processes is essentially Condentation polymer and Polyaddition.

b. Polykondensasi;

Ties of several molecules to form large macromolecules through the process of separation of one atom to bind small molecules from water. Of the process is formed of a material called Polykondensat

c. Polyaddition;

Namely the unification of several molecular basis through the placement of several molecules without any separation of the parts that are not fixed. Material that is formed is called "Polyadducf. In this reaction initiator is added to open the two bonds between carbon atoms and start the bonding process with the addition of more monomer to build a chain. For example Ethylene monomer binds to produce the polymer known as polyethylene.

The number molecular weight of the mer-mer in the polymer chain is the molecular weight of the polymer. The higher molecular weight in a given polymer, the greater the length of the chain. Since the polymerization is a random event, the resulting polymer chains are not all equal in length, but the resulting chain length formed in a traditional distribution curve. We define and express the average molecular weight of a polymer on a statistical basis by averaging. The spread of the molecular weight distribution is referred to as molecular weight distribution (MWD). Molecular weight and MWD have a strong influence on polymer properties. For example, broken and crushed strength, resistance to cracking, and viscosity in the liquid state all increase with increasing molecular weight. Most polymers that are traded have a molecular weight between 10,000 and 10,000,000.

In some cases, easier to describe the size of a polymer chain in the degree of polymerization (DP), defined as the ratio of molecular weight polymer with a molecular weight of repeating units. For example, polyvinyl chloride (PVC) has a weight of 62.5 mer, then the DP of PVC which has a molecular weight of 50,000 would be 50,000 / 62.5 = 800. In the polymerization process, the higher the DP, the greater the viscosity of the polymer, or flow resistance, then eventually facilitate the establishment and the overall cost.

During the polymerization of monomers bound together in a covalent bond, forming a polymer chain. Because of its strength, also called Primary covalent bonds. Besides holding the polymer chains with secondary bonds such as van der Waals bonding, hydrogen bonding and ionic bonding. Secondary bonds are weaker than primary bonds. In a polymer, increased strength and viscosity with molecular weight of a part from the fact that the longer the polymer chain, the greater the energy needed so that the secondary bonding is required.

If the repeating units of polymer chains is the same type, we call the homopolymer molecules. However two or three types of monomers that weight can be combined to get a special characteristic advantages, such as improving strength and endurance. Copolymer consists of two types of polymers such as Styrene-butadine, widely used for automobile tires. Terpolymer consisting of three types such as ABS is used for helmets, telephones.

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