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RESIN HANDLING MATERIALS & MATERIAL INTERACTIONS <br />Styrene based polyester resins are sensitive to contact with red metals and heavy metals. <br />In some cases interaction with these metals will inhibit the cure of the resins, while in <br />other cases it has been observed to uncharacteristically accelerate the cure. Commonly <br />found metals or metal coatings to avoid are: copper, brass, beryllium, chromium, lead, <br />and zinc (galvanized metal). Recommended choices for metals or plastics to be used for <br />storage and/or piping include carbon steel, stainless steel, aluminum, polyethylene, <br />polypropylene, and Teflon. Flexible resin transfer hoses must be made of chemically <br />resistant materials that are recommended for use with styrene monomer. Pumps and <br />gasket materials must also be approved for use with styrene monomer. <br /> <br />RESIN QUANTITY DETERMINATION <br /> <br />Before one can catalyze or mix the resin, it is necessary to determine the quantity of resin <br />required for the specific tube being prepared. <br /> <br />• First, determine the diameter, thickness and length of tube to be prepared. <br /> <br />• Using the manufacturer’s approved charts for the given resin, obtain the <br />approximate pounds of resin per linear foot for a given tube thickness and diameter. <br />Multiply this value by the length of tube to estimate to total quantity of resin for the <br />mix. Note that variations in the tube, as well as resin density, varies due to <br />temperature and manufacturer. It is due to the differences in resin density that <br />various charts are necessary for the different resins to estimate resin use per linear <br />foot of tube. <br /> <br />• Where multiple resin injections are necessary, one can closely estimate resin <br />usage/foot by dividing the quantity of resin consumed by the number of feet wet- <br />out. Occasionally resin usage will vary from that given in the attached table <br />because of variations in resin density and/or roller gap settings at the wet out <br />conveyer. Using an in-process calculated figure for the pounds of resin used per <br />linear foot will verify the accuracy of the value given in the table. If for some <br />reason the resin usage varies slightly from that given in the table, then the in- <br />process figure will provide a more accurate calculation of the quantity of resin to <br />complete the wet out. Calculating resin usage in this manner will increase the <br />accuracy of the wet out thereby saving time and/or resin. <br /> <br />SPECIFIC CURE CHEMICAL ADDITIONS <br /> <br />In order to determine the cure chemical mixture, one must first reference the resin <br />manufacturer guidelines for the recommended catalyst formulations. Concentrations of <br />chemical ingredients are modified in order to chemically control the curing heat of reaction <br />that is produced by the resin when it is transformed from a liquid to a solid. Increasing the <br />amount of peroxide used increases the amount of heat generated during the curing <br />process. In addition to controlling the heat liberated, adjusting the catalyst mixture also <br />affects the time before the resin will gel, and this is often referred to as "gel time." <br /> <br />Once the proper chemical formulation ratios have been chosen and the weight of resin in the drum <br />is known, one may calculate the amount of cure chemicals necessary for each mix. Document and <br />record this information. <br /> <br />