Polymers

Question 1

What are large molecules made of linked monomer units called?

Answer 1

Polymers

Examples of monomer units include vinyl chloride, styrene, and glucose.

Question 2

What are the four types of polymers?

Answer 2

• Natural (biopolymers)
• Semi-synthetic polymers
• Synthetic Polymers
• Co-polymers

Question 3

What is an example of a natural polymer?

Answer 3

Natural fibres, proteins, DNA

Examples include hemp and cotton.

Question 4

What are Rayon fibres and cellophane classified as?

Answer 4

Semi-synthetic polymers

Question 5

What are examples of synthetic polymers?

Answer 5

• PVC
• Polystyrene
• PTFE
• Nylon

Question 6

What is a co-polymer?

Answer 6

A polymer made from different linker monomers

Example: Styrene (25%) and 1,3-butadiene.

Question 7

What are the possible organisations of monomer units in co-polymers?

Answer 7

• Random co-polymers
• Alternating co-polymers
• Block co-polymers
• Graft co-polymers

Question 8

What describes branched polymers?

Answer 8

Polymers with high or low branching

Example: Polyethylene (LDPE and HDPE).

Question 9

What are cross-linked polymers?

Answer 9

Polymers where chains are interconnected

Examples: Poly (Isoprene) Rubber, Epoxy Resin.

Question 10

What characterizes linear polymers?

Answer 10

Polymers with a straight chain structure

Examples: PVC, Polystyrene, Nylon.

Question 11

What are dendrimers?

Answer 11

Specialised polymers engineered for specific uses

Question 12

What is chain growth polymerisation?

Answer 12

A method of synthesizing most plastics

Question 13

What are the three types of polymer classifications based on thermal properties?

Answer 13

• Thermoplastic
• Thermosetting
• Elastomer

Question 14

What is a thermoplastic?

Answer 14

A polymer that is hard at room temperature and soft at higher temperatures

Examples: Polystyrene, polyethylene.

Question 15

What happens to thermosetting polymers upon heating?

Answer 15

They become highly cross-linked and solidify

Question 16

What is an elastomer?

Answer 16

A polymer that can stretch and return to its original shape

Example: Rubber.

Question 17

What are fibres?

Answer 17

Thin threads

Question 18

Why are fibres important in forensic analysis?

Answer 18

They represent the largest category of polymer evidence analysed

Question 19

What are the classifications of fibres?

Answer 19

• Natural
• Semi-synthetic
• Synthetic

Question 20

What are cellulose fibres primarily composed of?

Answer 20

Cellulose

Example: Cotton fibres are made up of 90% cellulose.

Question 21

What are dicot fibres?

Answer 21

Fibres that come from a plant with two seed leaves

Question 22

What are characteristics of Kapok fibres?

Answer 22

• Smooth
• Hollow
• Buoyant
• Non-allergenic

Question 23

Which fibre is known for being stronger than cotton?

Answer 23

Flax (linen)

Question 24

What are the primary and secondary types of hemp fibres?

Answer 24

• Primary Bast Fibres (70%)
• Secondary Bast Fibres (30%)

Question 25

What characterizes ramie fibres?

Answer 25

Long, glossy, naturally white and silky appearance

Question 26

What are the general characteristics of synthetic fibres?

Answer 26

No surface characteristics and regular uniform shape

Question 27

What is Nylon made from?

Answer 27

6-aminohexanoic acid

Question 28

What are Kevlar fibres used for?

Answer 28

Bulletproof vests and other protective gear

Question 29

What are the properties of semi-synthetic fibres?

Answer 29

Regenerated forms of cellulose

Question 30

How are rayon fibres produced?

Answer 30

Extraction from wood pulp or cotton and treated with a strong base

Question 31

What is Cellulose?

Answer 31

A substance that gives plant and wood its strength ## Footnote Cellulose is a major component of the cell wall in plants.

Question 32

What percentage of cotton fibres is made up of cellulose?

Answer 32

90% ## Footnote Cotton is primarily composed of cellulose, making it a strong natural fibre.

Question 33

Define Dicot Fibre.

Answer 33

A fibre that comes from a plant with two seed leaves ## Footnote Examples include flax, hemp, and ramie.

Question 34

Describe the characteristics of Dicot fibres.

Answer 34

Transparent, colorless, curved twisted fibres with circular cross section and surface striations ## Footnote They are typically stronger than monocot fibres.

Question 35

What is Kapok?

Answer 35

A silky cotton-like substance with tiny cellulose tubes air sealed inside ## Footnote Kapok is used as a stuffing agent and is non-allergenic.

Question 36

What are the characteristics of Kapok fibres?

Answer 36

Smooth, hollow, thin-walled cylinders 2-3cm/10-35 um, twisting, and sharp bending ## Footnote Kapok can take on 30% of its weight in water.

Question 37

What is Flax (linen)?

Answer 37

A dicot fibre that is stronger than cotton due to its high concentration of cellulose ## Footnote Flax is often used in textiles.

Question 38

What are Hemp fibres?

Answer 38

Fibres from the cannabis plant, categorized into primary and secondary bast fibres ## Footnote Primary bast fibres are long and high in cellulose, while secondary bast fibres have medium length and high lignin.

Question 39

What is the composition of Ramie fibres?

Answer 39

Composed of cellulose with a long, glossy, naturally white appearance ## Footnote Ramie is considered one of the strongest natural fibres.

Question 40

List the uses of Jute.

Answer 40

* Cordage * Upholstery ## Footnote Jute fibres are soft and shiny, typically white to brown.

Question 41

What are Coir fibres used for?

Answer 41

Cordage and brushes, as well as floor mats and ropes ## Footnote Coir is derived from the husk of coconuts.

Question 42

Define Sisal.

Answer 42

A monocot fibre known for its flowing and soft fabric, expensive to convert ## Footnote Sisal comes from a plant with one seed leaf.

Question 43

What are the characteristics of Manila fibres?

Answer 43

Bundles of individual fibres used in the pulp for making brown envelopes ## Footnote Manila fibres have high magnification protuberances.

Question 44

Describe Silk.

Answer 44

A protein fibre that is pale yellow to brown/yellow with broad continuous ribbons ## Footnote Silk is produced by silkworms and is one of the strongest natural fibres.

Question 45

What is Cotton?

Answer 45

A seed fibre with thin threads and a ribbon-like shape that comes from seed pods ## Footnote Cotton fibres are typically yellow-white and about 2 inches long.

Question 46

What is the primary component of Cotton fibres?

Answer 46

90% cellulose ## Footnote Cotton is a seed fibre that plays a significant role in the textile industry.

Question 47

What does microscopic analysis of Cotton fibres allow?

Answer 47

Counting the number of fibres present ## Footnote This analysis helps in quality control and identification.