What is crystallinity of polymers?
Crystallinity defines the degree of long-range order in a material, and strongly affects its properties. The more crystalline a polymer, the more regularly aligned its chains. This usually consists of small crystalline regions (crystallites) surrounded by regions of amorphous polymer.
What does crystallinity mean?
Crystallinity can be defined as the degree of long-range structural order comprising a crystal lattice within a (solid) material.
Why do polymers crystallize?
Crystallization of polymers is a process associated with partial alignment of their molecular chains. Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation. Crystallization affects optical, mechanical, thermal and chemical properties of the polymer.
What affects crystallinity in polymers?
The size and structure of the crystals and the degree of crystallinity depend on the type and structure of the polymer, and on the growth conditions. Narrow molecular weight, linear polymer chains, and high molecular weight increase the crystallinity.
Why is it difficult to 100% crystallinity in polymers?
A polymer’s molecular structure strongly affects crystallinity. If it’s regular and orderly, highly symmetrical, it will pack into crystals more easily. In a way, the molecules want to get next to each other in crystalline domains. If the molecular structure is not highly regular and symmetrical, it won’t.
How does branching affect crystallinity?
Both the degree of branching as well as the length of the branches affects the density which can vary considerably. Typically, the higher the density of the polymer the higher the degree of crystallinity and the stiffer, harder, and stronger the polymer. However, these polymers are rather brittle.
What is meant by branching?
Branching is the practice of creating copies of programs or objects in development to work in parallel versions, retaining the original and working on the branch or making different changes to each.
What causes branching in polymers?
Branching is caused during polymerization at high pressure by growth sometimes starting from an initiation point in a chain rather than at the end. An alternative way of making polyethylene is at low pressure using a special catalyst, and this usually results in a highly linear chain without branching (HDPE).
Does branching increase viscosity?
The smaller coil size of a branched chain will tend to decrease the viscosity, although branches long enough to entangle produce a broadened terminal zone and larger viscosity.
What increases viscosity?
Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another. Thus the viscosity of a liquid depends on the: strength of attractive forces between molecules, which depend on their composition, size, and shape.
What are the factors that affect viscosity?
What factors affect viscosity? Viscosity is resistance to flow. For liquids, typically the larger the intermolecular forces (IMF) the higher the viscosity. The other factors that affect viscosity are temperature and the shape of the molecule.
How does branching affect polymer properties?
Branching also affects chain entanglement, the ability of chains to slide past one another, in turn affecting the bulk physical properties. Long chain branches may increase polymer strength, toughness, and the glass transition temperature (Tg) due to an increase in the number of entanglements per chain.
Which one of the following is branched polymer?
One of the most common example is low-density polyethylene (LDPE) and has applications ranging from plastic bags, containers, textiles, and electrical insulation, to coatings for packaging materials. Branched polymers display lower density as consequence of reduced packing efficiency of the branched chains.
Which of the following is linear polymer?
The examples of linear polymer are polythene, poly – vinyl chloride etc.
Which of the following is an example of condensation polymer?
It has acrylonitrile as monomeric units. – Both polythene and orlon are formed from free radical polymerization. – Therefore, terylene is an example of condensation polymer.
Is PVC a condensation polymer?
Generally, the PVC is a condensation polymer that has a pressure of 100 atmospheres at 200OC. The polyethylene has condensation polymers which are formed by the combination of monomer with the elimination of simple molecules such as H20 or CH3OH.
Is nylon a condensation polymer?
Nylon is a type of condensation polymer called a polyamide. Polyamides are created by reacting a type of monomer called a dicarboxylic acid together with another monomer called a diamine. The two monomers form an alternating chain, with water released as a side product of the reaction.
Is nylon 6 a condensation polymer?
Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization; this makes it a special case in the comparison between condensation and addition polymers.
Is protein a natural polymer?
Protein is a natural polymer formed from molecules called amino acids. Chicken nuggets and hamburgers have a lot of protein (but the bun has a lot of starch!). Protein is the main thing in skin, organs, muscles, hair and fingernails. The most common protein in your body, collagen, is used for support and structure.
Why is it called Nylon 6?
The nylon in the pictures on this page is called nylon 6,6, because each repeat unit of the polymer chain has two stretches of carbon atoms, each being six carbon atoms long. Other nylons can have different numbers of carbon atoms in these stretches. Nylons can be made from diacid chlorides and diamines.
Is nylon 6 a polyester?
Nylon is a synthetic polymer called a polyamide because of the characteristic monomers of amides in the backbone chain. Nylon 6,6: Two different molecules (adipic acid and hexamethylene diamine) are combined to create repeat units of 6 carbon atoms, thus the name nylon 6,6. …
What are 4 uses for nylon?
Uses of Nylon
- Clothing – Shirts, Foundation garments, lingerie, raincoats, underwear, swimwear and cycle wear.
- Industrial uses – Conveyer and seat belts, parachutes, airbags, nets and ropes, tarpaulins, thread, and tents.
- It is used to make a fishnet.
- It is used as plastic in manufacturing machine parts.
What are the uses of nylon 6?
Most nylon 6 is produced in the form of filament yarns and staple fiber yarns for the manufacture of carpets, tire cords, apparel, hosiery, upholstery, seat belts, parachutes, ropes, and industrial cords.
Why is nylon so strong?
The nylon molecules are very flexible with only weak forces, such as hydrogen bonds, between the polymer chains, which tend to tangle randomly. The polymer has to be warmed and drawn out to form strong fibres.
How is nylon harmful?
Nylon is also not a good fabric for you to wear either. Nylon does not absorb moisture so sweat is trapped against your skin, which creates a breeding ground for odour and fungal infection. An irritant known as formaldehyde is also found in nylon and has been linked to skin irritation and eye problems.
Is nylon stronger than steel?
Explanation: Nylon wire is stronger than steel wire ,if the diameter of both are same when subjected to tension . Nylon is a synthetic material made of repeated links linked by amide links whereas steel is not like nylon.
Is nylon The strongest Fibre?
Nylon fibers are exceptionally strong and elastic and stronger than polyester fibers. The fibers have excellent toughness, abrasion resistance, and are easy to wash, and to dye in a wide range of colors. The filament yarns provide a smooth, soft, and lightweight fabric of high resilience.
Which fiber is strongest?
Spider silk
Which one is the strongest Fibre?
Rayon
Which is strongest natural Fibre?
silk