Natural polymers, Mechanical Engineering

Assignment Help:

Natural Polymers

Rubber is individual natural polymer and was illustrated earlier. Specific trees exude thick liquid that solidified in brittle material termed as rosin. Shellac or lac is exudate result of animal life, parasitic insect or coccus lacca that feeds upon specific Indian trees. This material has extremely low tensile strength. While dissolved in spirit it can be utilized for polishing wooden surfaces. Wood is a naturally occurring polymer also that main constituent is cellulose. The cellulose molecule's chain is highly aligned. This alignment creates wood in mechanical properties to vary directional. The cellulose molecule is demonstrates in following figure.

                                                             271_Natural Polymers.png

                                                                       Figure: Cellulose Monomer of Wood

Wood is a living matter of cells composed that resemble long thin tubes. These tubes walls are made along with cellulose fibres that are aligned beside the axis. A complex amorphous material termed lignin binds cell walls together, and lignin makes 20 to 35 percent of wood by 50 to 60 percent cellulose. Minute percentages of resins, carbohydrates, minerals and gums are representing in wood also. Whilst the density of wood material is constant for each types of wood, the occurrence of voids and cracks of various sizes and numbers origin variation of density from one category to another. The hygroscopic nature of cell walls reasons absorption of water and swelling of wood. These water molecules behave extremely like plasticiser giving flexibility to wood. Removal of water creates wood rigid.

Organic acids do not attack wood on room temperature except the inorganic acids and alkaline solutions attack wood mostly at higher temperature and concentration. On prolonged heating at 105 to 150oC the organic matter begins to wood turns black and decomposes. Wood burns readily giving heat and thus used as like fuel. This can be mechanically and chemically treated to generate wood pulp that is employed for producing paper.


Related Discussions:- Natural polymers

Elastomers, define elastomer.explain in details?

define elastomer.explain in details?

Separator-battery components , Separator:   Separator works as insulator b...

Separator:   Separator works as insulator between positive and negative plates. These separators are placed between each pair of plates.

Low resistance or very high current in primary coil circuit, If Low Resista...

If Low Resistance or Very High Current in Primary Coil Circuit Causes of Problem Remedy Primary ignition coil short circuited

Welding of pressure parts in boilers, This section covers welding of pressu...

This section covers welding of pressure parts including those non-pressure parts when welded to pressure parts. All welding design functions necessary within the contract shall be

What is hydraulic press, (i) Hydraulic press:   This can be used...

(i) Hydraulic press:   This can be used to lift a heavy load placed on the platform of larger piston or to press the things placed among the piston and the heavy platfor

Lifting machine, all information about lifting machine

all information about lifting machine

Describe dry and wet parting materials, Q. Describe Dry and wet parting mat...

Q. Describe Dry and wet parting materials? Dry parting materials: These are applied by dusting. These include : charcoal, ground bone and limestone, lycopodium(a yellow veget

Illustrate torsionally equivalent shaft, (a) Illustrate Torsionally Equival...

(a) Illustrate Torsionally Equivalent shaft. (b) Determine the natural frequencies and mode shapes for the system shown in figure I 1 = 10 Kg -m 2 I 2 = 40 Kg -m 2

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd