Polymeric resins surface properties

The resins are known to be hydrophobic as well as lyophobic, that is, with a low affinity for hydrocarbons. Although heavy hydrocarbons have high polarizabilities, the lyophobicity results from the weakness of electric fields on the surfaces of the polymeric resins. This property makes the resin an ideal candidate for modification as highly selective sorbents for separation and purification. After modification by ion exchange with a cation such as Ag", the sorbent will be highly selective for hydrocarbons that have r-electrons, while little of the hydrocarbons without 7r-electrons wiU be adsorbed. 

Plastics. Plastics are the polymeric materials with properties intermediate between elastomers and fibers. In spite of the possible differences in chemical structure, the demarcation between fibers and plastics may sometimes be blurred. Polymers such as polypropylene and polyamides can be used as fibers and plastics by a proper choice of processing conditions. Plastics can be extruded as sheets or pipes, painted on surfaces, or molded to form countless objects. A typical commercial plastic resin may contain two or more polymers in addition to various additives and fillers. Additives and fillers are used to improve some property such as the processability, thermal or environmental stability, and mechanical properties of the final product. 

The range of surface resistance obtainable with conductive textiles based on polypyrrole or polyaniline (10-10,000 /2/D) allows these materials to be used for a number of applications. The use of such fabrics as reinforcements to polymeric resins results in composites that have interesting and well-controlled electrical properties. These unusual electrical properties are quite evident in the microwave region of the electromagnetic spectrum. The literature on microwave properties of such composites is not extensive, but some results have been reported by researchers in the United States, the United Kingdom, and France [68,71-74]. 

EFFECT ON POLYMER AND/OR OTHER ADDITIVES Figure 11.1 shows the effect of cetyl stearate on the reduction of the ejection force. Figure 11.2 shows the effect of an internal release agent on some mechanical properties. The combinations of ester type release agents, such as discussed in Figures 11.1 and 11.2, were patented." Silicone oil sprayed on a mold surface was found to reduce ejection force in the consecutive shots, but ejection force increased by about 20% in 10 shots following spray application. Ejector pin pressure was reduced by about 50% with the addition of 3,000 ppm of paraffin wax, or 3,000 ppm behenate with 30 ppm of stearic acid. A polymeric resin... 

Numerous avenues to produce these materials have been explored (128—138). The synthesis of two new fluorinated bicycHc monomers and the use of these monomers to prepare fluorinated epoxies with improved physical properties and a reduced surface energy have been reported (139,140). The monomers have been polymerized with the diglycidyl ether of bisphenol A, and the thermal and mechanical properties of the resin have been characterized. The resulting polymer was stable up to 380°C (10% weight loss by tga). 

Amino resins react with ceUulosic fibers and change their physical properties. They do not react with synthetic fibers, such as nylon, polyester, or acryhcs, but may self-condense on the surface. This results in a change in the stiffness or resiHency of the fiber. Partially polymerized amino resins of such molecular size that prevents them from penetrating the amorphous portion of ceUulose also tend to increase the stiffness or resiHency of ceUulose fibers. 

For rosins and rosin esters, the produets having high aeid numbers are the most susceptible to oxidation and have inferior viscosity stability and colour stability in adhesive formulations. Thus, when stability properties are essential in adhesives, rosin esters rather than high aeid number rosins are used. However, the high acid number resins are polar and display better adhesion to polar elastomers and polymeric surfaces. 

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