Factors Affecting the Polymer’s Properties:

Factors Affecting the Polymer’s Properties:

• Effect of Temperature on Polymers: 

Solids on heating eventually melt to form a liquid. With polymers it is not so simple rubber on cooling (in liquid nitrogen) becomes brittle or glassy. Many polymers have a mixture of ordered (crystalline) regions and random (amorphous) regions. In the glassy state, the tangled chains in the amorphous region are frozen so movement of chains is not possible the polymer is brittle. If the glassy material is heated, the chains reach a temperature at which they can move. This temperature is called the glass transition temperature. Above this temperature the polymer is flexible. At the melting point, the crystalline regions break down and the polymer becomes a viscous liquid.

• The Physical Properties of a Polymer Depends on: 

• Chain Length:

The physical properties of a polymer are strongly dependent on the size or length of the polymer chain. Long chains get tangled up in each other and stick together far more than short chains. This means that polymers made of long chain molecules have higher melting points than those made of short chains. Increasing chain length furthermore tends to decrease chain mobility, increase strength and toughness, and increase the glass transition temperature shorter molecules can pass over each other more easily so materials made of these molecules are softer and more ‘squishy’. 

• Side Group:

The attractive forces between polymer chains play a large part in determining a polymer’s properties. Because polymer chains are so long, these iner-chain forces are amplified far beyond the attractions between conventional molecules. Polar side groups give stronger attraction between polymer chains, making the polymer stronger, different side group on the polymer can lend the polymer to ionic bonding or hydrogen bonding between its own chains. These stronger forces typically result in higher tensile strength and higher crystalline melting points.

• Branching:

The branching of polymer chains affects their ability to slide past one another by altering intermolecular forces, in turn affecting bulk physical polymer properties. Long chains branches may increase polymer strength, toughness and the glass transition temperature due to an increasing in the number of entanglements per chain. The effect of such long-chain branches on the size of the polymer in solution is characterized by the branching index. Random length and atactic short chains, on the other hand, may reduce polymer strength due to disruption of organization and may likewise reduce the crystallinitiy of the polymer.

Polyethylene - Low & High Density LDPE HDPE LDPE

Low Density Polyethylene, the first of the polyethylenes to be developed, is characterized by good toughness, resistance to chemicals, flexibility and clarity. It's an excellent material in electrical and chemical uses in low heat applications. 

Applications

•Chemical Resistant Tanks and Containers
•Food Storage Containers
•Laboratory Equipment
•Disposable Thermoformed Products
•Corrosion Resistant Work Surfaces
•Corrosion Resistant Wall Coverings
•Lavatory Partitions
•Man-hole Covers - Chemical Plants
•Radiation Shielding
•Self Supporting Containers
•Prosthetic Devices

HDPE

High Density Polyethylene is more rigid and harder than lower density materials. It also has higher tensile strength, four times that of low density polyethylene. It is three times better in compressive strength and meets FDA requirements for direct food contact applications. 

• Cross-linking 

Rubber and some other polymers can be cross-linked. A chemical reaction takes place that connects the chains to each other permanently. This makes the whole structure more rigid and less elastic. It also makes the material a lot stronger and harder. Vulcanization or vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives." These additives modify the polymer by forming crosslinks (bridges) between individual polymer chains.^[1] Vulcanized material is less sticky and has superior mechanical properties. A vast array of products is made with vulcanized rubber including tires, shoe soles, hoses, and hockey pucks. The process is named after Vulcan, Roman god of fire. Hard vulcanized rubber is sometimes sold under the brand names ebonite or vulcanite, and is used to make hard articles such as bowling balls and saxophone mouth pieces.

Conclusion

All in all, polymers are large molecules that consist of tiny unites there are two types of polymers, synthetic and natural. To add, these polymers can be formed by either addition or condensation polymerization.

Ever since their discovery in 1920, polymers have helped revolution our life. We have been witnessing how synthetic polymers were introduced to our life, making a tremendous debut. Also, the study of natural polymers has lent a hand in the medical and nutritional field.

Our new would industry relies on various polymers. Synthetic silk, for instance, have been industrialized to increase their proficiency they, nowadays, can be easily cleaned; as a result, they are used in cloths.

More interestingly, their properties can be affected by different factors. The diversity of their properties is useful to human. Strength, toughness, melting point and transport properties can be affected. The main factors that change their properties are temperature, chain length, side groups, branching and cross linking.

Research focus in polymers revolves now around that fact that polymers properties dependence on these factors is a major benefit; in fact, it is the perfect way to produce more diverse and efficient polymers.