1. Studies of Carbon fibre
composites
By
Dhanraj Desai

2. Introduction
 Composites
Engineered or naturally occurring materials made from two or
more constituent materials with significantly different physical or
chemical properties which remain separate and distinct at the
macroscopic or microscopic scale within the finished structure.
E.g.- Concrete, Plywood.

3. Why composites?
 Weight Saving
 Directionality
 Excellent fatigue
 Cost
 Ease of Assembly
 Don’t corrode
 Ease of fabrication
 Wide range of shapes
 Inherent Mechanical Properties
 Tailor ability
 Special Features

4. Composites

5. Fibres used in composites
 Carbon
 Kevlar
 Kenaf
 Bamboo
 Hemp
 Glass
 Coir
 Jute
 Sisal
 Flax

6. Why carbon fibre?
 Light in weight, Strong and Durable
 Good vibration damping and toughness
 High dimensional stability
 Low co-efficient of thermal expansion
 Low abrasion
 Electrical conductivity
 Biological inertness
 X-Ray permeability
 Fatigue resistance
 Self lubrication property
 High damping
 Electromagnetic properties
 Chemical inertness
 High corrosion resistance

7. Why sisal fibre?
 Exceptionally durable with low maintenance
 Minimal wear and tear
 It is recyclable
 Anti-static property
 It exhibits good sound and impact absorbing properties

8. Motivation of Work
Advantages of Sisal fibre
 Abundance and therefore low cost,
 Biodegradability,
 Flexibility during processing and less
resulting machine wear,
 Minimal health hazards,
 Low Density,
 Desirable fiber aspect ratio,
 Relatively high tensile and flexural
modulus
Advantages of Carbon fibre
 70% Lighter than steel, 40% lighter than
aluminium
 High strength to weight ratio
 High corrosion resistance
 Application flexibility
 Low mass
 It can be formed to most any shape

9. challenges
In Sisal Fibre
 Variable quality, depending on
unpredictable influences such as
weather.
 Moisture absorption, which causes
swelling of the fibres.
 Restricted maximum processing
temperature.
 Lower durability, fibre treatments can
improve this considerably.
 Poor fire resistance
In Carbon Fibre
 Carbon fibre in extremely expensive
 Recycling in very difficult
 Once a carbon fibre structure dinted or
cracked cannot beat it back

10. Methods of Surface Modification
For Natural Fibre
 Physical methods of modification
 surface fibrillation, electric
discharge(corona, cold plasma)
 Alkali Swelling and Substitution
Reactions
 Impregnation of Fibers
 Chemical Modification
 Silane Treatments
For Carbon Fibre
 Physical methods of modification
 Chemical modification
 Silane Treatment

11. Composite Manufacturing Methods
Hand Laminating Resin Injection Technique
Hot Press Method Pultrusion

12. Literature Survey
 In 2009 Yunsheng Xu, D.D.L.Chung, treated carbon fibre with silane coupling
agent and silane treated silica fumes.
And found the tensile strength of cement paste was increased by 56% and the
modulus and ductility were increased by 39%. Silane treatment of fibers and silica
fume contributed about equally to the strengthening. Silane treatment of fibres
and silica fume also decreased the air void content and the drying shrinkage. The
strengthening, air void content reduction and drying shrinkage reduction were
less when the fibre treatment involved either potassium dichromate or
ozone.Silane’s effectiveness is due to its hydrophilic nature.
Silane-treated carbon fiber for reinforcing cement, Carbon 39 (2001) 1995-2001

13. Cont…
 Yanjun Xie, Callum A. S. Hill, Zefang Xiao, Holger Militz, Carsten Mai, carried out a
variety of silanes (mostly tri alkoxy silanes) have been applied as coupling agents in the
NFPCs to promote interfacial adhesion and improve the properties of composites,
And they found the interaction mechanisms between natural fibers and polymer matrices,
and presents the effects of silane treatments on the mechanical and outdoor performance
of the resulting composites.
Silane coupling agents used for natural fiber/polymer composites : A review, Composites Part A 41
(2010) 806-819.

14. Cont.…
 In 2007,P.Noorunnisa Khanam,H.P.S.Abdul Khalil, M. Jawaid, G.Ramachandra Reddy,
C.Surya Narayana, S.VenkataNaidu, studied
1) The variation of mechanical properties such as tensile and flexural properties of randomly
oriented unsaturated polyester based sisal/carbon fibre reinforced hybrid composites with
different fibre weight ratios.
2) The chemical resistance test of these hybrid composites to various solvents,acids and
alkalies.
3) The effect of NaOH treatment of sisal fibres on the tensile, flexural and chemical
resistance properties of these sisal/carbon hybrid composites.
And found
1) The hybrid composites showed an increase in tensile and flexural properties with increase
in the carbon fibre loading.
2) The tensile properties and flexural properties of these hybrid composites have been
found to be higher than that of the matrix.

15. 3) Significant improvement in tensile properties and flexural properties of the
sisal/carbon hybrid composites has been observed by alkali treatment.
4) The resistance test results showed that these untreated and alkali treated hybrid
composites are resistance to all chemicals except carbon tetrachloride.
Sisal/Carbon Fibre Reinforced Hybrid Composites :Tensile, Flexural and Chemical Resistance
Properties, J Polym Environ (2010).

16. Cont.……
 K.Bilba, M.-A. Arsene, describes the effect of two silane compounds on parameters
such as the porosity, dimension, morphology and hygroscopic character of silane-
coated sugar cane bagasse fibers.
They studied natural fiber reinforced composite setting times how the importance of
the silane chemistry/structure, for fiber treatments with silane solution containing up
to 6%(volume per cent) silane. In the case of composites reinforced with unpyrolyzed
bagasse fibers, setting time increases with silane coating. Combining pyrolysis and
silane treatment improve the water resistance of the fibers, which become more
hydrophobic.
Silane treatment of bagasse fiber for reinforcement of cementitious composites, Composites
:Part A 39 (2008) 1488-1495

17. Cont.……
 Noor Sabah Sadeq, carried out reinforcing the matrix (Epoxy) resin with natural material
(cane sugar fibers) and synthetic fibers (chopped carbon fibers). The natural fibers were
exposure to chemical treatment before reinforcement.
The hybrid composites contain of chopped carbon and cane sugar fibers is produced using
hand lay method. Each sample was reinforced with different volume fraction such as 30%,
20%, and 10%.
Cane sugar composite has the higher values (of flexural strength 490.77 MPa and of impact
strength 93.92 KJ/m2) than chopped carbon composites (flexural strength 93.19 MPa and
impact strength 23.92 KJ/m2).
It was found that the additions of natural fibers (cane sugar) to chopped carbon fibers
improve of the mechanical properties of hybrid composites.
Influence of Natural Fiber on the Mechanical Properties of Epoxy Composites.

18. Cont.….
 IIn 1999 L.Y.Mwaikambo and M.P.Ancell treated hemp, sisal, jute and kapok varying
concentrations of caustic soda and acetylated with and without an acid catalyst to
graft acetyl groups onto the cellulose structure.
And found After treatment the surface topography of hemp, sisal and jute fibres is
clean and rough. The surface of kapok fibres is apparently not affected by the
chemical treatments. X-ray diffraction shows a slight initial improvement in the
crystallinity of the fibres at low sodium hydroxide concentration.

19. Plan of Work
 Fibres
Carbon Fibres, Sisal, Jute and Coir (As per the availability)
 Resin
Polyester, Polypropylene, Epoxy
 Surface modification method
Mercerisation, drying, silane treatment.
 Manufacturing Process
Hand lay up/ compression moulding.

20. Properties of Composites
 Scan Electronic Microscopy(SEM)
 FTIR
 Tensile property
 Thermal (TGA,DSC)
 Moisture
 Swelling in water
 Compression

21. Applications

23. Thank You