Mastication and Mixing

An entirely new concept was iatroduced iato mbber technology with the idea of "castable" elastomers, ie, the use of Hquid, low molecular-weight polymers that could be linked together (chain-extended) and cross-linked iato mbbery networks. This was an appealing idea because it avoided the use of heavy machinery to masticate and mix a high viscosity mbber prior to mol ding and vulcanization. In this development three types of polymers have played a dominant role, ie, polyurethanes, polysulftdes, and thermoplastic elastomers. 

Thomas Hancock (1785-1865) is designated the father of the rubber industry and to him Great Britain is indebted for the honour of being the first country to manufacture rubber successfully as a large-scale project. His first major discovery, in 1819, was the process of masticating and mixing raw rubber. His subsequent claim, in his Personal Narrative published in 1857, that this was unquestionably the origin and commencement of the India-rubber manufacture, properly so called , has been amply verified since. 

Rubber which has been masticated in an operation entirely separate from the mixing process proper. See Mastication and Mixing. Premix... 

It is a well-known fact that most of the properties of rubber are complex due to its great deformability, i.e., when a piece of rubber is stretched or compressed in one direction it is compressed or stretched in another direction respectively. Rubber in fact behaves like a solid in one direction and like a liquid in another two directions. Two samples of rubber of the same composition and vulcanized side by side may give different test results due to variations in the early treatment of the rubber such as mastication and mixing or milling. 

A machine for masticating rubber, mixing rubber compounds and for warming up rubber compounds prior to calendering, extrusion, etc. See Open Mill. 

The absorption efficiency of the different carotenoids is variable. For example, (3-cryptoxanthin has been reported to have higher absorption efficiency than a-cryptoxanthin in rats (Breithaupt and others 2007). Carotenoids must be liberated from the food before they can be absorbed by intestinal cells (Faulks and Southon 2005). Mechanical disruption of the food by mastication, ingestion, and mixing leads to carotenoid liberation (Guyton and Hall 2001). The enzymatic and acid-mediated hydrolysis of carbohydrates, lipids, and proteins (chemical breaking of the food) also contributes to carotenoids liberation from the food matrix (Faulks and Southon 2005). Once released, carotenoids must be dissolved in oil droplets, which are emulsified with the aqueous components of the chyme. When these oil droplets are mixed with bile in the small intestine, their size is reduced, facilitating the hydrolytic processing of lipids by the pancreatic enzymes (Pasquier and others 1996 Furr and Clark 1997 ... 

Food is taken into the buccal cavity, where it is masticated by the teeth and mixed with saliva from three pairs of salivary glands. It moistens the food and dissolves some molecules enabling them to interact with the taste receptors on the tongue. Saliva contains Na% Cl and HCOs ions and a protein, mucin, which is a component of mucus that lubricates the chewed food on its way down the oesophagus. The pH of saliva is about 7.8, which neutralises acid formed by bacteria in the mouth this protects tooth enamel... 

Syntheses have been carried out on polymer-polymer, polymer-monomer, and polymer-filler systems. The properties of the products obtained can vary widely according to chemical structure and the conditions of mastication (temperature, mixing intensity, presence and nature of radical acceptors and stabilizers, atmosphere, solvents and ratio of blend components). 

Blue Stars. Rub fine and mix 20 parts of chlorate of potassium, 11 of sulphur, 14 of cupric oxide, and 1 of mastic. 

Yellowish-green Stars. I. Rub fine and mix 60 parts of chloride of barium, 30 of nitrate of. barium, 20 of sulphur, and 1 of mastic. 

Yellow Candles. Rub fine and mix 80 parts of sodium nitrate, 7 of sulphur, 3 of sodium sulphide, ana 2 of mastic. 

Red Candies. Rub flue and mix 26 parts of nitrate of strontium, 15 of chlorate of potassium, 12 of flowers of sulphur, 2 of charcoal, 2 of sodium sulphide, and 1 of mastic. 

Thus, the Mooney units measure the extent of mastication or the plastic flow of rubber to enable better dispersion and mixing of ingredients and curatives. In addition to this, the Mooney units can give an indication of the curing nature of compounded uncured rubbers. 

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