Physical changes during processing

All nutrients (except water) may undergo either chemical or physical changes during processing that render them inactive or less bioavailable. This occurs for macro- as well as micronutrients. During browning, the amino acid lysine can react with carbohydrates to lower the biological value of protein. 

Reactively modified polymers are polymer systems that have been chemically or physically changed during processing. Reactively modified polymers may be classified in terms of their production by the following processing techniques ... 

An absorbent material is one which changes either chemically, physically, or both during the sorption process. Certain chemicals, in absorbing moisture during this process, will dissolve into the water from the initial crystalline structure. Further added water results in a phase change from solid to liquid. An adsorbent is another material in which there are no chemical, phase, or physical changes during the sorption process. 

S.4.3.3 Physical and Chemical Flavour Changes during Processing and Shelf-Life... 

Some preformed compatibilizers, such as Kraton [93] and Vector [94], are commercially available and ready for use. Priex [95] maleic anhydride terminated polyolefins (PP-MA and PE-MA) are commonly used to compatibilize minor levels of contamination in PE and PP streams. Other postformed compatibilizers require a reaction or chemical or physical change during the mixing or processing step before they show efficacy. Materials used as postformed compatibilizers are generally not compatibilizers themselves but, because of an in sim reaction, result in compatibilization. 

Materials used must be exceedingly wel. cations should include melt index, hardneii properties, and other mechanical and physic residual monomer, catalysts, modifiers, ant kinetics of chemical changes during process is important, since changes in composition, in vivo, could alter the permeation rate oi of the system. Ordinarily an initial purif quired for polymers obtained commercially t additives that would be prone to leach out... 

In the presence of excess fatty acid, different soap crystalline phase compounds can form, commonly referred to as acid—soaps. Acid—soap crystals are composed of stoichiometric amounts of soap and fatty acid and associate in similar bilayer stmctures as pure soap crystals. There are a number of different documented acid—soap crystals. The existence of crystals of the composition 2 acid—1 soap, 1 acid—1 soap, and 1 acid—2 soap has been reported (13). The presence of the acid—soaps can also have a dramatic impact on the physical and performance properties of the finished soap. The presence of acid—soaps increases the plasticity of the soap during processing and decreases product firmness, potentially to the point of stickiness during processing. Furthermore, the presence of the acid—soap changes the character of the lather, decreasing the bubble size and subsequently increasing lather stabiUty and... 

With rubber base adhesives, it is necessary to prevent their properties from changing during service life. Oxidative changes induced by thermal, ozone exposure and UV light can dramatically affect service life of rubber base adhesives. More precisely, the rubber and the resin are quite susceptible to oxidative degradation. Environmental and physical factors exert detrimental effects on rubber base adhesive performance. These effects can be mitigated by the incorporation of low levels of stabilizers during the fabrication process of the adhesive. 

Proposed reaction mechanisms have suggested that in many rate processes the nature of the conducting species may change during the course of decomposition. There is evidence [364] that, even in the absence of pyrolysis, the conducting entity may vary with the physical form of the reactant. 

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