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Forced Degradation
Forced degradation or accelerated degradation is a process whereby the natural degradation rate of a product or material is increased by the application of an additional stress. Introduction Forced degradation studies are used to identify reactions which may occur to degrade a processed product. Usually conducted before final formulation, forced degradation uses external stresses to rapidly screen material stabilities. Longer-term storage tests are usually used to measure similar properties when final formulations are involved because of the stringent FDA regulations. These tests are generally more expensive (because of the time involved) than forced degradation which is therefore used for rapid selection and elimination tests. Common stresses There are a number of common stresses which are used to * pH (acid/base) Chemical processes are often catalysed by the presence of acids and bases. The exposure of materials to these can therefore accelerate degradation reactions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arrhenius Equation
In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and reverse reactions. This equation has a vast and important application in determining the rate of chemical reactions and for calculation of energy of activation. Arrhenius provided a physical justification and interpretation for the formula. Laidler, K. J. (1987) ''Chemical Kinetics'', Third Edition, Harper & Row, p. 42 Currently, it is best seen as an empirical relationship.Kenneth Connors, Chemical Kinetics, 1990, VCH Publishers It can be used to model the temperature variation of diffusion coefficients, population of crystal vacancies, creep rates, and many other thermally-induced processe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Decomposition
Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fragments. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction. The details of a decomposition process are not always well defined but some of the process is understood; much energy is needed to break bonds. Since all decomposition reactions break apart the bonds holding it together in order to produce into its simpler basic parts, the reactions would require some form of this energy in varying degrees. Because of this fundamental rule, it is known that most of these reactions are endothermic although exceptions do exist. The stability of a chemical compound is eventually limited when exposed to extreme environmental conditions su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermogravimetric Analysis
Thermogravimetric analysis or thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes. This measurement provides information about physical phenomena, such as phase transitions, absorption, adsorption and desorption; as well as chemical phenomena including chemisorptions, thermal decomposition, and solid-gas reactions (e.g., oxidation or reduction). Thermogravimetric analyzer Thermogravimetric analysis (TGA) is conducted on an instrument referred to as a thermogravimetric analyzer. A thermogravimetric analyzer continuously measures mass while the temperature of a sample is changed over time. Mass, temperature, and time are considered base measurements in thermogravimetric analysis while many additional measures may be derived from these three base measurements. A typical thermogravimetric analyzer consists of a precision balance with a sample pan located inside a furnace with a programma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Productive Maintenance
Total Productive Maintenance (TPM) started as a method of physical asset management focused on maintaining and improving manufacturing machinery, in order to reduce the operating cost to an organization. After the PM award was created and awarded to Nippon Denso in 1971, the JIPM (Japanese Institute of Plant Maintenance), expanded it to include 8 pillars of TPM that required involvement from all areas of manufacturing in the concepts of lean Manufacturing. TPM is designed to disseminate the responsibility for maintenance and machine performance, improving employee engagement and teamwork within management, engineering, maintenance, and operations. There are eight types of pillars TPM: # focused Improvements # JH Pillar (Autonomous Maintenance) # PM pillar (Planned Maintenance) # QM pillar (Quality Maintenance) # DM pillar (Development Maintenance) # E&T pillar (Education and Training) # OTPM (Office TPM) # SHE Pillar (Safety, Health and Environment) History Total Productive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
