Fulvio - Applications of Composites and Natural Fibre Composites

Question 1

8 advantages of Natural Fibre Composites (NFC)

Answer 1

• environmentally friendly through whole lifecycle
• low energy production
• use common production methods
• similar properties to glass fibres, but less dense
• excellent acoustic and vibration insulation
• can make 100% biodegradable composite when reinforcing natural polymers
• better reaction to fire

Question 2

6 disadvantages of rNatural Fibre Composites (NFC)

Answer 2

• lower stiffness and strength compared to synthetic
• variable quality depending on natural factors
• moisture absorption causes swelling
• limited max processing temp
• lower durability than synthetics
• fluctuating price depending on harvests etc

Question 3

3 main classifications of natural fibres

Answer 3

Animal, vegetable, mineral

Question 4

which category are lignocelulosic natural fibres in (LCF)

Answer 4

vegetable

Question 5

List 4 Natural Fibre Reinforcement materials

Answer 5

• flax / linseed
• hemp
• jute
• bamboo

Question 6

properties of Flax as a natural fibre

Answer 6

• light weight
• good damping and acoustic properties
• sustainable production
• good aesthetic properties
• good fatigue properties compared to glass fibres
• similar modulus to Glass fibres
• strongest natural fibre available

Question 7

properties of hemp as a natural fibre

Answer 7

• cheap
• high tensile strength and stiffness
• similar properties to glass fibres, but lower density
• easy to process and recycle
• customisable, consistent quality

Question 8

properties of Jute as a natural fibre

Answer 8

• cheapest
• medium tensile strength, low extensibility, high breathability
• versatile
• already used in automotive and furniture industries

Question 9

properties of bamboo as a natural fibre

Answer 9

• extremely resilient and durable
• high ventilation and high moisture absorption
• possible environmental issues with harsh chemicals often used in cultivating
• anti bacterial properties?

Question 10

3 types of matrix material which can be used for natural fibre composites (NFC)

Answer 10

thermosets, thermoplastics, rubber/natural polymers

Question 11

Key considerations when deciding the fibre content in a NFC

Answer 11

• strength peaks around 50% matrix volume fraction
• stiffness peaks at 65% matrix volume fraction
• fibre content limited due to challenges of fibre/matrix interfacial strength
• critical volume fraction due to water absorption and porosity
• matrix selection limited by temp

Question 12

what manufacturing methods are used for NFC’s

Answer 12

traditional composite manufacturing techniques

Question 13

key considerations when using extrusion to manufacture NFCs

Answer 13

SCREW SPEED:
- too high causes air entrapment and fibre breakage
- too low causes poor mixing and insufficient wetting

Question 14

key considerations when using injection moulding to manufacture NFCs

Answer 14

fibre orientation will vary across mould due to shear flow along mould walls

Question 15

key considerations when using compression moulding to manufacture NFCs

Answer 15

Temperature and holding time:
- compromise between reduced fibre strength and good wetting

Question 16

key considerations when using RTM AND VARTM to manufacture NFCs

Answer 16

• avoidance of thermal degradation is advantageous
• issues with compaction

Question 17

What does good wettability mean

Answer 17

good ability for matrix to penetrate and attach to fibres

Question 18

List 5 applications of NFCs

Answer 18

• Buildings - insulation, panels, internal walls
• Furniture - boards and pieces with flame retardant properties
• Automotive
• Aerospace - mostly internal features
• Sporting goods

Question 19

list 8 future challenges with NFCs

Answer 19

• lack of fibre consistency in quality
• low impact strength
• stocking issues due to degradation etc
• foul odour development
• Low UV resistance
• fibre degredation during processing
• fibre orientation and distribution

Question 20

Possible solutions to future challenges with NFCs

Answer 20

• fibre pre-treatments can enhance NFC interfacial adhesion and improve mechanical properties

Question 21

Advantages of polymer matrix composites (PMCs) in aerospace

Answer 21

• weight reduction
• high strength
• tailored mechanical properties with lay up
• thermal stability - dont expand/contract
• little corrosion and fatigue issues

Question 22

advantagees of PMC in automotive

Answer 22

• cost reduction
• weight reduction
• structural advantages

Question 23

advantages of thermoplactic FRPs in automotive

Answer 23

• no solvent emissions
• reduced material scrap
• improved work safety conditions
• improved recyclability

Question 24

which manufacturing methods can be used for thermoplastics

Answer 24

• injection moulding
• filament winding
• compression moulding
• (pre-preg)