2.0 LITERATURE REVIEW 2.1 Polyurethanes Polyurethane is an organic polymers, it was first discovered by Prof. Dr Otto Bayer in 1937. Polyurethanes are defined as polymers which contain urethane groups (-NH-CO-O-) in the main chain. However, as the versatility uses of this type of polymers, urethane group is not usually the principle group presents, other groups such as ester, ether, amine and urea groups are generally contained in the chain in reasonable number. Urethanes group present in the chain is the result from the reaction between molecules containing two or more hydroxyl (-OH) groups per molecules and isocyanates that have more than one reactive isocyanate group (-NCO) per molecule as for example reaction between diisocyanates with diol as shown in Figure 1. The reaction occurs in such a way hydrogen moves from diol to the nitrogen of diisocyanate while the oxygen of diol link with carbon on diisocyanate (Ophardt,
Ring-flipping process happens as it converts to a twist boat conformation and next to a new chair conformation. Carbon number one flips to point up for the purpose achieving a twist boat form. Then, carbon number 4 can flip to point down to achieve another chair conformation. When carbons which opposite position flip like this, interconverting all axial and equatorial bonds; that is, all axial forms become equatorial forms while all equatorial forms become axial forms. Chair conformer of cyclohexane has 7 kcal/mol which is more stable compared to boat conformer of cyclohexane because destabilization of boat forms of cyclohexane by torsional strain due to the hydrogens on the four carbon atoms in the plane are eclipsed.
However, Jeffrey Muldoon (Muldoon, 2006) stressed in his article “The Hawthorne Legacy” that The Hawthorne studies (1924-1932) are the most famous of all management research but also the most criticized. According to Richard Herbert Franke and James Kaul (Kaul, 1978) , aside from visual inspection and anecdotal comment, the complex of data obtained during the eight years of the Hawthorne experiments has never been subjected to thorough-going scientific analysis (Franke, 1979). An article “The Hawthorne Experiments: First Statistical Interpretation” was published on 1978 that provides review of the data and analytical procedure applied in the study. The authors also cited several published documents stating the tendency of some people to work harder and perform better when they are participants in an experiment (Cherry, n.d.) – Hawthorne
YDROGEN SENSORS REPORT ON: HYDROGEN SENSORS & EXTRACTING HYDROGEN FROM WASTEWATER Extraction of Hydrogen from Sewage Page 27 Hydrogen sensors are of increasing importance in connection with the development and expanded use of hydrogen gas as an energy carrier and as a chemical reactant. A hydrogen sensor is a gas detector that detects the presence of hydrogen. They contain micro-fabricated point-contact hydrogen sensors and are used to locate hydrogen leaks. They are considered low-cost, compact, durable, and easy to maintain as compared to conventional gas detecting instruments There are an immense number of sensors reported in the literature for hydrogen detection and in this work these sensors are classified into eight different operating
3.8 Research papers which are referred as reference : 1. Apparatus for controlling tapping-drilling machine-US08738028 An apparatus for controlling a tapping-drilling machine is disclosed in which holes can be formed by means of drilling tools, and threads can be formed by means of tapping tools. A worm is elongately formed on a spindle, and a worm wheel which is meshed with the worm is secured by a lateral shaft. At the leading end of the lateral shaft, there is installed a brake. In the preferred embodiment of the present invention, the electronic type brake is employed, and the electric current flowing through this brake is adjusted, so that the velocity of the vertical movement of the spindle sleeve (which is defined to be the ratio of the vertical moving distance to the revolutions of the spindle) can be automatically adjusted.
2.1.2 Methods of Soap Production Soap production methods upgraded when two scientific findings were made in the late eighteenth and early nineteenth centuries. In 1790, the French chemist Nicolas Leblanc (1742-1806) designed a process for producing caustic soda (Sodium hydroxide) from common table salt (Sodium chloride). His invention made low-priced soap manufacture possible by aiding chemists to develop a procedure whereby natural fats and oils can react with caustic soda. The method was advanced when another French chemist, Michel Eugene Chevreul (1786-1889), revealed the nature of the fats and oils as soap production became less expensive and attitudes towards public health and hygiene changed, soap making became a significant industry.
MICROPROPAGATION: PRINCIPLE The practice of propagation of a plant under ‘aseptic conditions’, for the production of its clones, is known as ‘micropropagation’. It is a technique which comes under plant tissue culture. This technique allows large number of plants to be produced from the explants in less time. Through micropropagation, various ‘difficult-to-root’ species can be effectively reproduced clonally; but the cost is high which has resulted in its prevention for a wider application in market . The following stages are involved during this process: • Stage 0 – Preparative/ Pre-initiation stage: Explant selection and sterilization takes place.
Rotomoulding process is a sophisticated technology that utilizes High Density Polyethylene (HDPE) material which is highly resistant to stress cracks. It is the company’s working culture and commitment to maintain the Rotocraft Quality. 4.3.2 Competitor B - Perstorp sdn. bhd. Perstorp sdn.