Investigation in to Mechanical and Tribological Behavior of Biomass Based Carbon Black Filled Epoxy Composite

Abstract

Over the last few years, ecological concern and global warming has initiated a considerable interest in using natural materials to produce green products and reduce anthropogenic carbon dioxide emissions by all possible means. Kyoto protocol has further highlighted this issue by which many countries including India has committed to reduce combined CO2, CH4 and N2O emissions. India and China are becoming important players in the Global GHG arena. The CO2 emission in these countries increased by 9% and 6% respectively in 2011, relative to the previous years of their share in global CO2 emission now equals that of Organization for Economic Co-operation and Development (OECD).
In the present scenario, natural fibers have excellent potential to reduce not only CO2 emissions but also save non-renewable resources by substituting glass fiber reinforcements in plastic composites. Traditionally, glass fibers/wool has been extensively used as building insulation material and reinforcement in auto sector thermoplastics. However, environmental performance of glass fiber mat thermoplastics (GMTs) has several drawbacks due to extensive energy consumption and potential health risks during production and handling. Glass fibers cause severe abrasion to process equipment and their composites may transform into sharp splints during collision causing extra injuries to passengers. Moreover GMTs are non-recyclable and their incineration generates clinker like mass that is hard to dispose off except land filling.
There are many potential natural resources, which India has in abundance. Most of it comes from the forest and agriculture. Wood apple (Aegle marmelos) belongs of family rutaceae is highly reputed medicinal tree. Its fruit is commonly known as the “Stone apple” or “Bael”. It is an indigenous fruit of India and found abundantly in sub-Himalayan forest, Bengal central, south India, Sri Lanka, Pakistan, Bangladesh, Burma, and Thailand. The peel of the fruit is very hard. Wood apple shell contains 39.54% cellulose, 26.06% hemicellulose, and 30.86% lignin. Coconut (Cocos nucifera) is a member of the palm family. The coconut palm is used for decoration as well as for culinary and non-culinary uses; virtually every part of the coconut palm has some human use. Coconut shell is non-food part of coconut, which is hard lignocellulosic agro-waste. Coconut shell consists of 30.04% cellulose, 20.16% hemicellulose, and 25.76% lignin.If the density (low) of these materials is taken in to consideration, then its specific stiffness and strength are comparable to the respective quantities of glass fibers. The wood apple shell and coconut shell composites can be very cost-effective material especially for pipe lines carrying coal dust, slurries, desert structure, low cost housing, boats/sporting equipment, partition boards, doors and window panels.
As far as composite industries are concerned in recent period, carbon has been one of the outstanding elements that have revolutionized science of materials. Carbon provides the materials with excellent properties for a wide range of industrial applications. From carbon we receive the strongest fibers (carbon fibers), to one of the best solid lubricants (graphite), one of the best electrically leading materials (graphite electrodes), the best structural material for high temperature tribological application (carbon–carbon composites), one of the best porous absorbers (activated carbon), an essentially non-crystalline impermeable material (vitreous carbon), the hardest material (diamond), and now the most fascinating material, the fullerenes. All these forms are made by meticulously choosing the raw materials and processing conditions Over the last century the production of carbon black (CB) is found to be relatively very expensive, which is produced by incomplete combustion of oil feed stocks. As a result the focus is now shifting towards agricultural waste products which are found to be good source of raw materials for the production of CB. This CB is produced by the pyrolysis of coal, wood, coconut shell, oil palm shell, jute, banana, bamboo, and other lignocellulosic biomass based materials which are carbonaceous in nature and rich in organic materials. Such agricultural by-products are usually inexpensive, for which the effective utilization has not been tried so far. It is unlikely that the use of products made from renewable resources will provide a complete solution to the pressing problems of industrial society.
The activated carbon was introduced for the first time industrially in the first part of the 20th century, Activated carbon is a trade name for a carbonaceous adsorbent, which can be prepared from a large number of carbonaceous raw materials including agricultural and forestry residues by either a physical method or a chemical method. The most commercial products are made from agricultural waste such as coconut shell, bamboo, wood, sawdust, hard shell, nut shells and fruit pits. Therefore the present research work has been under taken with an objective to produce carbon and activated carbon from the natural waste (wood apple shell and coconut shell) in the laboratory by utilizing the method of pyrolysis process. It is also planned to use these raw, carbon and activated carbon as reinforcing material in polymer composite of different weight fraction 5, 10, 15 and 20wt%. Direct usage of natural filler alone in polymer composite is inadequate in satisfactorily tackling all the technical needs of a fibre reinforced composite. It is reported that if natural fibre are carbonized to remove the waste material (volatiles and moisture) and increase the carbon percentage the strength of the composites are increased.
In this work an attempt has also been made to prepare carbon and activated carbon from wood apple shell and coconut shell. Efforts are made to study the effect of carbonization temperature on the tensile strength, flexural strength, tensile modulus and flexural modulus of the composite. Experiment is also carried out to study the erosive wear behavior of the composite developed. Effect of different parameters like impingement angle and velocity on the erosive wear behavior of carbon and activated carbon composite has also been studied and reported in the thesis. The test results indicate that there is an increase in both tensile and flexural and as well as the modulus for raw, carbonous and activated carbon of wood apple and coconut particulate filled composites. The trend observed for both wood apple and coconut particulate are almost same and the trend is raw<carbon black (400°C<600°C<800°C)<activated carbon black (800°C). The erosion efficiency (η) values obtained experimentally also confirm that the raw particulates (wood apple and coconut) composite exhibit semi ductile erosion response whereas carbonized and activated carbon reinforced composites exhibited semi-brittle and brittle response.