Date post: | 16-Jan-2016 |
Category: |
Documents |
Upload: | pushparajpingulkar |
View: | 39 times |
Download: | 2 times |
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
THANK YOU