Additives polymer modification through

Polymer modification through additives is ultimately related to the affinity of the additive to the matrix which is controlled by physical and chemical interactions. The selection of mixing configuration which in turn, depends on the nature of the additive (low viscosity liquid, low molecular weight solid, melt, liquid) also affects the performance of the additive. Additives forming distinct dispersed morphologies may be deformable or rigid... 

The continuing developments in the preparation of dendrimers and hyper-branched polymers ° have moved this field into consideration by the polymer colloids community. As dendrimers and hyperbranched polymers get ever larger, their dimensions become sufficient to consider their solutions as molecular polymer colloids. Inevitably, therefore, research into such polymers will feature in new directions for polymer colloids research, both as polymer colloids in their own right and as additives for modification of the properties of existing polymer colloids. Such research will be most effective if carried out through collaborations of organic and polymer chemists with colloid scientists. 

Furthermore, modification of polymer properties through additives contributes decisively to the use of commodity plastics in demanding applications that have been the traditional field of engineering plastics. 

FIGURE 7.1 Schematic of a lab-scale 200 mm diameter iCVD reactor system. For a vinyl homopolymerization, a constant flow of monomer and initiator is metered into the pancake -style vacuum reaction chamber. An array of resistively heated wires, suspended a few centimeters above the substrate, heats the vapors. Laser interferometery provides real-time monitoring of the iC VD polymer thickness. The pressure of the chamber is controlled by a throttling value. Unreacted species and volatile reaction by-products are exhausted to a mechanical pump. For copolymerization, an additional monomer feed line would need to be added to the system (top image). Schematic cross-section of the iCVD reactor showing decomposition of the initiator by the heated filaments. Surface modification through polymerization of the monomer occurs on the actively cooled substrate (bottom image). 

Cover image is adapted from Steward, P.A., Hearn, J. 8c Wilkinson, M.C. (1995) Studies in permeation through polymer latex films. 11. Permeation modification by sucrose addition. Polymer International 38 (1), 13-22. Copyright Society of Chemical Industry. Reproduced with permission. Permission is granted by John Wiley 8c Sons Ltd on behalf of the SCI. 

Tailoring Polymer Properties through Modification, Additives, and Reinforcement... 

The properties of polymers are determined by the nature and composition of the structural units, as well as the molecular architecture. Polymers are most often made from the corresponding monomers. In comparison with developing new monomers and polymerization methods, a less expensive route to tailor-making of polymers is through blending, copolymerization, architecture control during polymerization, post-polymerization chemical modification, and additives. Detailed discussions on such possibilities are available in several reviews [37-42]. Here we will briefly highlight two recent developments in the areas of block copolymers and polymeric nanocomposites. 

Polyacrylate leveling additives are homopolymers or copolymers of acrylates with alkyl, polyester or polyether modifications. They are normally supplied as solvent-free materials or as solutions. The performance of these additives is tailored through variations in their chemical composition (polarity and type of monomers) and MW, because their solubility and compatibility in coatings are dependent on these factors. Linear acrylic polymers are more incompatible than branched ones and those with higher MW are more incom-... 

Coloration through polymer modification or dye-receptor addition before extrusion or by adding dye to the melt. Films, fibres, and tapes are coloured almost exclusively with concentrate granules, the amount of which varies between 1 and 10% in correlation with the depth of the shade required, thickness and opacity, fastness to light, rubbing, and washing. 

The modification of natural polymers to introduce or modify their amphiphilic character can take two general approaches (1) degradation processes such as hydrolysis to reduce molecular weights or break crosslinking bonds to increase water solubility in normally insoluble materials such as cellulose (2) chemical modification through the addition of molecular components that alter the nature of the molecules, usually involving esterification, amination, oxidation, etherification, or similar reactions and (3) enzymatic modifications. 

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