Effect of plasticizers on product properties

Water sensitivity and solubihty can be conveniently regulated by the use of a combination of plasticizers. In hotmelts that are water sensitive, two groups of plasticizers are used in different proportions depending on required properties. Larger amounts of water soluble plasticizers such as polyethylene glycol mono- and di-laureates increase water sensitivity. Addition of larger amounts of water insoluble plasticizers, such as 2-ethyl-hexyl diphetyl phosphate or butyl benzyl phthalate, increases the hydrophobic properties of hotmelt.  

Addition of plasticizer to polyurethanes can be done in several ways in the beginning of synthesis of prepolymer, at the last stages of synthesis, and during adhesive/sealant 

6 EXAMPLES OF FORMULATIONS Water-based, wallboard adhesive  

Dispersant (aromatic sulfonic acid, sodium salt) 0.07 

Styrenated terpene tackitying resin (Zonatac 105LT) 29.1 Cyclohexane dimethanol dibenzoate (Benzoflex 352)18.9 

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EFFECT OF PLASTICIZERS ON PRODUCT PROPERTIES Rheological properties of PVC pastes can be conveniently modelled by Ostwald-deWaele, ... 

Both this melt temperature and the glass transition of the resultant material are highly susceptible to the presence of plasticizers. The dominant species is water, but small sugars and salts may also have an influence (see Chapter 5). Nonetheless, it is clear that whereas the processes in the extruder barrel should be related to the effect of plasticizers on gelatinisation or melting, their effect on final product properties should be related to the glass transition of the amorphous molten extrudate. 

If one could conclusively show that there is an effect of plasticizers on reaction rate that is independent of moisture content or a , then this would demonstrate the significance of matrix properties for governing reaction rate. Labuza et al. (1977) studied the Maillard reaction and measured the effects of several parameters. These included temperature, reactant concentration, pH, buffers, and the addition of humectants. The formulation consisted of glucose and casein as reactants within a carrier matrix of microcrystalline cellulose and an inert lipid. Reaction rate was measured both as glucose loss, lysine loss, and pigment production (A42o). 

The first major paper on mold release was published in 1946 by Ziegler. It contained a thorough analysis of the influence of mold material on release properties. Even more important, the paper contained a proposal for a new method of mold release testing, which gave the fundamental tool for rational analysis of the problem. More than twenty of the so-called mold lubricants were tested by the newly developed pull-out force method. In addition, the effect of lubricant on product clarity was observed - both results being considered in the final selection. In the best cases, the decrease of up to 80% of pull-out force was obtained with these tested lubricants . Plasticizers and pigments were also found to facilitate mold release properties in combination with mold release agents. 

Because of its tunable density and low viscosity, synthetic organic chemists are beginning to utilize supercritical C02 as a medium for exploring reaction mechanisms and solvent cage effects [10,11]. Asymmetric catalysis represents an area in which supercritical C02 may be useful as a solvent [12]. For polymerization reactions, in particular, the solvency of C02 as a medium and the plasticization effects of C02 on the resulting polymeric products represent the properties of central importance. These significant properties of C02 are explored in detail below. When all of these factors are combined with the fact that C02 may obviate the use of much more expensive and hazardous solvents,... 

If the emulsion polymerization product is retained in the water phase for use it is referred to as a PTEE dispersion. The very strong C-E bonds, plus the strengthening effect of these on the C-C bonds confers extraordinarily stable properties to this polymer. The chemical inertness, excellent electrical resistance, high-heat resistance, nonstick properties, and low coefficient of friction combine to make PTFE one of the highest performance commercial vinyl plastics produced (Table 23.3). 

FIGURE 5.97 Effect of plastic type (polyethylene o, polypropylene A, polystyrene X) and wood loading levels on properties of wood plastic composites. (After Chelsea Center for Recycling and Economic Development (CCRED), 2000. Technical Report 19, An Investigation of the Potential to Expand the Manufacture of Recycled Wood Plastic Composite Products in Massachusetts, Univ. of Massachusetts, Massachusetts.)... 

Conventional plasticizers may be used in formulated products. Phthlate esters are the preferred plasticizers. They exhibit little tendency to migrate and have good compatibility with both resins and hardeners. Addition rates are typically 5 to 20%. Chlorinated plasticizers may be used to reduce flammability, especially in conjunction with antimony trioxide. The effect of plasticizer additions is generally to degrade most physical properties, although at low additions the effect is usually small. The effect of plasticizer additions on various important properties is as follows ... 

The above list created on the basis of experimental findings and products development shows importance of plasticizers for the properties of materials manufactured from PVC. These effects are discussed in many parts of this book and their importance for some groups of products are discussed in Chapter 13. The above list may be frequently consulted to evaluate potential changes in material caused by plasticizer addition (also in the case of other polymers). 

All these thermal properties relate to how to determine the best useful processing conditions to meet product performance requirements. There is a maximum temperature or, to be more precise, a maximum time-to-temperature relationship for all materials preceding loss of performance or decomposition. This section therefore reviews important thermal properties. More details about ASTM standards are given in Chapter 9. The effects of temperature on plastics are discussed throughout this book, particularly in Chapters 3-6. 

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