Fulvio - Applications of Composites and Natural Fibre Composites COPY

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

properties of Flax as a natural fibre

Answer 3

• 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 4

properties of hemp as a natural fibre

Answer 4

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

Question 5

properties of Jute as a natural fibre

Answer 5

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

Question 6

properties of bamboo as a natural fibre

Answer 6

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

Question 7

Key considerations when deciding the fibre content in a NFC

Answer 7

• 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 8

key considerations when using extrusion to manufacture NFCs

Answer 8

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

Question 9

key considerations when using injection moulding to manufacture NFCs

Answer 9

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

Question 10

key considerations when using compression moulding to manufacture NFCs

Answer 10

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

Question 11

key considerations when using RTM AND VARTM to manufacture NFCs

Answer 11

• avoidance of thermal degradation is advantageous
• issues with compaction

Question 12

list 8 future challenges with NFCs

Answer 12

• 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 13

Possible solutions to future challenges with NFCs

Answer 13

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

Question 14

which manufacturing methods can be used for thermoplastics

Answer 14

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