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SUMMARY REPORT PLASTICS INTERMEDIATES POLYESTER RESINS HIGH PURITY ASBESTOS AS A THIXOTROPE FOR POLYESTERS Authors: C. W. McGary P. L. Smith Dot*: March 18, 1965 Project No.: 119E21 File No.: 3780 SUMMARY High purity asbestos from the Mining and Metals Division can be used as a viscosity modifier and thixotropic aid in polyesters. A concentration of 2.5-3.0 per cent asbestos in a hand lay-up polyester provides thixotropy equivalent to 1.0 per cent Cab-o-sil. INTRODUCTION Polyester resins (40 per cent styrene) for hand lay-up and spray-up applications customarily are modified by addition of 1.0 per cent Cab-o-sil. Reportedly,(!) viscosity of the resulting polyester, measured using a #2 spindle and a model LVT Brookfield viscometer, is as follows: Rpm Viscosity range, cps 6 900-1300 12 750-900 30 600-750 60 400-500 The purpose of this study was to determine whether high purity asbestos (6-8<{/lb.) could be used as a replacement for Cab-o-sil (72-74f/lb. ) / DISCUSSION The polyester used in this study was prepared using 2.0 moles of phthalic anhydride per 1.0 mole of maleic anhydride and a 10 per cent excess of propylene glycol. Viscosity, after dilution to 40 per cent styrene, was 275 cpoise (ref: 149PLS118). Table I shows the effect of high purity asbestos and Cab-o-sil on viscosity of the polyester at 25C. It is apparent that-between 2.5 and 3.0 per cent asbestos provides thixotropy equivalent to 1.0 per cent Cab-o-sil. All of the samples showed signs of filler settling upon standing 1-2 hours at room temperature. Settling rate of asbestos was slower as the concentration increased. Research and Development Department Chemicals Division Union Carbide Corporation I TABLE I COMPARISON OF EFFECT OF HIGH PURITY ASBESTOS AND CAB-O-SIL ON VISCOSITY OF A HAND LAY-UP POLYESTER (40% STYRENE) Thixotrope HP Asbestos 2% 2.5% 3.0% Viscosity^1^ <g 25C. , cps 6 6 rpm 12 rpm 30 rpm 60 rpm 725 663 588 >500 900 813 692 >500 1350 1225 >1000 >500 Cab-o-sil 1.0% 1150 913 665 >500 Ref: 149PLS124 and 125 (1) Using a #2 spindle and a model LVT Brookfield viscometer. DISTRIBUTION Mr. R. D. Bower, NYO Hr. L. R. Comstock, 511 Mr. D. Lee, NYO Mr. C. P. McClelland, TNY Mr. A. . Montagna, 511 Mr. C. T. Patrick, 511 Mr. N. S. Setter, Mining and Metals Div. Mr. J. Sidlovsky, NYO Dr. S. W. Tinsley, 511 Information Retrieval Authors