Selection of Natural Fiber for Polypropylene Based Composite

Abhilash 2014PG0259Abhilash V 2014PG0249Amit Jangamshetti 2014PG0316Nithin M 2014PG0328Pingulkar Pushparaj Ramchandra 2014PG0121Samir Kulkarni 2014PG0283

Overview

• Introduction• Classification of natural fibers• Constituents of natural fiber composites• Factors affecting properties of composite• Selection of natural fiber and matrix material• Results and discussion• Conclusion

Introduction

• Why natural fibers?– they are renewable, inexpensive, completely or partially

recyclable, and biodegradable

• Examples: flax, cotton, hemp, jute, sisal, kenaf, pineapple, ramie, bamboo, banana, wood……..– easily available, renewability, low density, as well as

satisfactory mechanical properties

Classification of natural fibers

Constituents of natural fiber composites

• Plant based natural fibres are composed of– cellulose : major framework component; provides strength,

stiffness and structural stability of the fiber– hemicelluloses : form cementing materials for the fiber

structure– lignin and pectin : provide adhesive quality to hold

molecules together – cause for strength and stiffness properties of the fiber

– waxy substances

Constituents of natural fiber composites

Structure of natural fiber

Factors affecting properties of composite

• Fiber structure• Thermal stability– degradation of natural fibers starts at about 240ºC– individual constituents degrade at different temperatures– ex: lignin starts degrading at a temperature around 200ºC – enhancement of thermal properties possible by removing

certain proportions of hemicellulose and lignin by chemical treatment

• Fiber length (aspect ratio), loading and orientation

Factors affecting properties of composite

• Presence of voids– Voids are formed due to improper curing and cooling rates– More than 20% void content will result in lower fatigue

resistance, greater affinity to water diffusion and increased scatter in mechanical properties

• Moisture absorption– leads to dimensional instability, matrix cracking and poor

mechanical properties of the composites– moisture absorption of fibres can be reduced by eliminating

hydrophilic hydroxyl groups from the fiber structure through different chemical treatments

Selection of natural fiber and matrix material

• Study based on 5 natural (plant) fibers:– Hemp, – Jute, – Sisal, – Banana, and – Flax

• Matrix material - polypropylene

Selection of natural fiber and matrix material

Mechanical properties of the fiber and matrix material

 Properties

 Natural Fibers

 Matrix

 Hemp

 Jute

 Sisal

 Flax

 Banana

 Polypropylene

 Density (g/cm3 )

 1.48

 1.46

 1.33

 1.4

 1.3

 0.95

 Tensile strength 

(MPa)

 550-900

 400-800

 600-700

 800-1500

 540

 31 to 42

 E-Modulus (GPa)

 70

 10-30

 38

 60-80

 30

 1 to 1.4

 Specific 

modulus(E/ρ)

 47

 7-21

 29

 26-46

 23.07

 1.05 to 1.47

Selection of natural fiber and matrix material

• For selection of best natural fiber - specific modulus of the composite in longitudinal and transverse direction was calculated for each fiber and matrix combination

1Specific modulus in longitudinal directionc

E

2Specific modulus in transverse directionc

E

Selection of natural fiber and matrix material

• Density of the composite

• Longitudinal and transverse modulii

1c m f f fV V

1 m m f fE E V E V

2

1 f m

f m

V V

E E E

Results and discussion

E1 vs. Vf

Results and discussion

E1/ρ vs. Vf

Results and discussion

E2 vs. Vf

Results and discussion

E2/ρ vs. Vf

Conclusion

• The specific moduli both in longitudinal and transverse direction are increasing with increasing fibre volume fraction

• Among all the fiber composites, Flax reinforced with polypropylene composite shows steeper curve compared to others where as the jute showed the less steep curve.

• This shows that flax fiber reinforced polypropylene composite gives better strength both in longitudinal and transverse directions.

Conclusion

• The theoretical calculations using rule of mixture suggest that flax fibers are better to select out of five natural fibers

• However it is required to prove practically by fabrication and testing

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