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Mullins Effect
The Mullins effect is a particular aspect of the mechanical response in filled rubbers, in which the stress–strain curve depends on the maximum loading previously encountered. The phenomenon, named for rubber scientist Leonard Mullins, working at the Tun Abdul Razak Research Centre in Hertford, can be idealized for many purposes as an instantaneous and irreversible softening of the stress–strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times, when the load is less than a prior maximum, nonlinear elastic behavior prevails. The effect should not be confused with the Payne effect. Although the term "Mullins effect" is commonly applied to stress softening in filled rubbers, the phenomenon is common to all rubbers, including "gums" (rubber lacking filler). As first shown by Mullins and coworkers, the retraction stresses of an elastomer are independent of carbon black when the stress at the maximum strain is constant. Mullins softeni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mullins Effect
The Mullins effect is a particular aspect of the mechanical response in filled rubbers, in which the stress–strain curve depends on the maximum loading previously encountered. The phenomenon, named for rubber scientist Leonard Mullins, working at the Tun Abdul Razak Research Centre in Hertford, can be idealized for many purposes as an instantaneous and irreversible softening of the stress–strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times, when the load is less than a prior maximum, nonlinear elastic behavior prevails. The effect should not be confused with the Payne effect. Although the term "Mullins effect" is commonly applied to stress softening in filled rubbers, the phenomenon is common to all rubbers, including "gums" (rubber lacking filler). As first shown by Mullins and coworkers, the retraction stresses of an elastomer are independent of carbon black when the stress at the maximum strain is constant. Mullins softeni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubbers
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and Indonesia are three of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the Hevea brasiliensis, rubber tree (''Hevea brasiliensis'') or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale. Natural rubber is used extensively in many applications and products, either alone or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonard Mullins
Leonard Mullins (1918 – 19 September 1997) was a scientist and long-time Research Director at the former Malaysian Rubber Producers' Research Association. He is known for his work on the stress-softening behavior of rubber, a phenomenon now known widely as the Mullins effect. Personal Mullins was born on 21 May 1918 and died on 19 September 1997 at the age of 79. Leonard was the eldest of 7 children, with his brothers Eric, Kenneth, John, known as Alan, and sisters Sylvia, Muriel and Eugenie. He married Freda Churchouse on 6 March 1943 and had 2 daughters Margaret and Janet. Education Mullins graduated from University College London in 1939 BSC (Hons), PhD, DSc Career He had originally hoped to enter academia, but World War II interrupted his plans and he ended up working in weapons research for the British government. In 1949, he oversaw the dismantling of the Bayer A.G. rubber labs and pilot plant at Leverkusen, Germany. In 1950, he joined the physics group of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tun Abdul Razak Research Centre
The Tun Abdul Razak Research Centre, originally known as the British Rubber Producers' Research Association, carries out research into rubber and is funded by the Malaysian government. Early years: as the British Rubber Producers Research Association: 1938 to 1957 The British Rubber Producers Research Association was formed as a scientific research organization in 1938 'to understand rubber and in pursuit of this aim to mount a programme of fundamental research', since at that time the technology was almost entirely empirical.Biographical Memoirs of Fellows of the Royal Society (1999) vol 45 pp 185-194 It carried out fundamental work on rubber, which included the more general polymer science and the physics and mathematics of rheology and in addition contributed to early work on electronic computers. Prominent in the push for greater rubber research and the establishment of the association was Sir Eric Miller, who became chairman of the BRPRA. In 1939, it obtained its first prem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertford
Hertford ( ) is the county town of Hertfordshire, England, and is also a civil parish in the East Hertfordshire district of the county. The parish had a population of 26,783 at the 2011 census. The town grew around a ford on the River Lea, near its confluences with the rivers Mimram, Beane, and Rib. The Lea is navigable from the Thames up to Hertford. Fortified settlements were established on each side of the ford at Hertford in 913AD. The county of Hertfordshire was established at a similar time, being named after and administered from Hertford. Hertford Castle was built shortly after the Norman Conquest in 1066 and remained a royal residence until the early seventeenth century. Hertfordshire County Council and East Hertfordshire District Council both have their main offices in the town and are major local employers, as is McMullen's Brewery, which has been based in the town since 1827. The town is also popular with commuters, being only north of central London and connect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastic (solid Mechanics)
In physics and materials science, elasticity is the ability of a Physical object, body to resist a distorting influence and to return to its original size and shape when that influence or force is removed. Solid objects will Deformation (engineering), deform when adequate Structural load, loads are applied to them; if the material is elastic, the object will return to its initial shape and size after removal. This is in contrast to Plasticity (physics), ''plasticity'', in which the object fails to do so and instead remains in its deformed state. The physical reasons for elastic behavior can be quite different for different materials. In metals, the Crystal structure, atomic lattice changes size and shape when forces are applied (energy is added to the system). When forces are removed, the lattice goes back to the original lower energy state. For rubber elasticity, rubbers and other polymers, elasticity is caused by the stretching of polymer chains when forces are applied. Hoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Payne Effect
The Payne effect is a particular feature of the stress–strain behaviour of rubber, especially rubber compounds containing Filler (materials), fillers such as carbon black. It is named after the British rubber scientist A. R. Payne, who made extensive studies of the effect (e.g., Payne 1962). The effect is sometimes also known as the Fletcher-Alan Neville Gent, Gent effect, after the authors of the first study of the phenomenon (Fletcher & Gent 1953). The effect is observed under cyclic loading conditions with small strain amplitudes, and is manifest as a dependence of the viscoelasticity, viscoelastic dynamic modulus, storage modulus on the amplitude of the applied Deformation (engineering)#Elastic deformation, strain. Above approximately 0.1% strain amplitude, the storage modulus decreases rapidly with increasing amplitude. At sufficiently large strain amplitudes (roughly 20%), the storage modulus approaches a lower bound. In that region where the storage modulus decreases the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastomer
An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic polymer'', is often used interchangeably with rubber, although the latter is preferred when referring to vulcanisates. Each of the monomers which link to form the polymer is usually a compound of several elements among carbon, hydrogen, oxygen and silicon. Elastomers are amorphous polymers maintained above their glass transition temperature, so that considerable molecular reconformation is feasible without breaking of covalent bonds. At ambient temperatures, such rubbers are thus relatively compliant ( E ≈ 3 M Pa) and deformable. Their primary uses are for seals, adhesives and molded flexible parts. Application areas for different types of rubber are manifold and cover segments as diverse as tires, soles for shoes, and damping and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Black
Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid catalytic cracking tar, and ethylene cracking. Carbon black is a form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon. It is dissimilar to soot in its much higher surface-area-to-volume ratio and significantly lower (negligible and non-bioavailable) polycyclic aromatic hydrocarbon (PAH) content. However, carbon black can be used as a model compound for diesel soot to better understand how diesel soot behaves under various reaction conditions as carbon black and diesel soot have some similar properties such as particle sizes, densities, and copolymer adsorption abilities that contribute to them having similar behaviours under various reactions such as oxidation experiments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constitutive Equation
In physics and engineering, a constitutive equation or constitutive relation is a relation between two physical quantities (especially kinetic quantities as related to kinematic quantities) that is specific to a material or substance, and approximates the response of that material to external stimuli, usually as applied fields or forces. They are combined with other equations governing physical laws to solve physical problems; for example in fluid mechanics the flow of a fluid in a pipe, in solid state physics the response of a crystal to an electric field, or in structural analysis, the connection between applied stresses or loads to strains or deformations. Some constitutive equations are simply phenomenological; others are derived from first principles. A common approximate constitutive equation frequently is expressed as a simple proportionality using a parameter taken to be a property of the material, such as electrical conductivity or a spring constant. However, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finite Element
The finite element method (FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential. The FEM is a general numerical method for solving partial differential equations in two or three space variables (i.e., some boundary value problems). To solve a problem, the FEM subdivides a large system into smaller, simpler parts that are called finite elements. This is achieved by a particular space discretization in the space dimensions, which is implemented by the construction of a mesh of the object: the numerical domain for the solution, which has a finite number of points. The finite element method formulation of a boundary value problem finally results in a system of algebraic equations. The method approximates the unknown function over the domain. The simple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
