Homework SourseHow many types of polymers molecular structures Define each
Solution
Types of Polymer Molecular Structues are:
1)Cross linked polymer structure:
Cross-linking is where the polymer chains are chemically joined together in places, by covalent bonds. The polymer molecules cannot slide over each other so easily. This makes materials tougher and less flexible, and they cannot be easily stretched. Cross-linking also gives materials high melting points.
Vulcanised rubber has cross-links. Its polymer molecules are cross-linked by sulfur atoms. It is tough but flexible, and used for making tyres.
2) Linear or chain polymer structure:
The ability for molecules to form long chains is a vital to producing polymers. Consider the material polyethylene, which is made from ethane gas, C2H6. Ethane gas has a two carbon atoms in the chain and each of the two carbon atoms share two valence electrons with the other. If two molecules of ethane are brought together, one of the carbon bonds in each molecule can be broken and the two molecules can be joined with a carbon to carbon bond. After the two mers are joined, there are still two free valence electrons at each end of the chain for joining other mers or polymer chains. The process can continue liking more mers and polymers together until it is stopped by the addition of anther chemical (a terminator), that fills the available bond at each end of the molecule. This is called a linear polymer and is building block for thermoplastic polymers.
3) Branched polymer structure:
Polymers with branches at irregular intervals along the polymer chain are called branched polymers.These branches make it difficult for the polymer molecules to pack in a regular array, and therefore make the polymer less crystalline. Cross-linked polymers contain branches that connect polymer chains.There are, however, many ways a branched polymer can be arranged. One of these types is called \"star branching\". Star branching results when a polymerization starts with a single monomer and has branches radially outward from this point. Polymers with a high degree of branching are called \"dendrimers\". Often in these molecules, branches themselves have branches. This tends to give the molecule an overall spherical shape in three dimensions.
4)Network structure polymers:
A Network polymer is a network in which all polymer chains are interconnected to form a single macroscopic entity by many crosslinks. Network structure polymers are essentially highly dense cross linked polymers.They are a group of polymers in which a single large network, instead of many molecules is formed during polymerization. Since polymerization is initially accomplished by heating the raw materials and brining them together, this group is called thermosetting polymers or plastics. For this type of network structure to form, the mers must have more than two places for boning to occur; otherwise, only a linear structure is possible. These chains form jointed structures and rings, and may fold back and forth to take on a partially crystalline structure.
