Document wr1wYg1KpKd2xM2QNGd7vwmYo

VY-T2 THE GENERAL TIRE & RUBBER COMPANY CHEMICAL/PLASTICS DIVISION . AKRON, OHIO Effect of Molecular Weight on PVC Properties PVC polymer can be made in a wide range of chain lengths or molecular weights. For control and identification purposes, the molecular weight is characterized by the polymer's intrinsic viscosity in a solvent solution. The higher molecular weight' polymers possess higher tensile strength and hardness, better resistance to flow at elevated temperatures, and improved solvent resistance, when compared to their lower mulecular weight homologs. Resin Vygen 85 Vygen 105 Molecular Weight*___________ .____. Intrinsic Viscosity____________ Tensile Strength, psi** _______ _____ Ultimate Elongation, %** ___ Tensile Stress at 100% Elongation, psi** ___ _____ Shore A Hardness,' 0 Sec. ____________________ 10 Sec. 74,000 .80 2160 230 1290 91 80 83,000 .93 2490 300 1400 91 80 Formulation _________________ ___ Resin -- 100 parts DOP -- 50 parts Ba-Cd Stabilizer -- 2 parts Vygen 110 93,000 1.03 2730 340 1420 91 81 Vygen 120 107,000 1.18 2890 350 1460 92 82 * D. J. Mead and R. M. Fuoss, J. American Chemical Society, 64, 277, (1942). ** ASTM D-412-61T. The table above illustrates a typical formulation using 50 parts of dioctyl phthalate (DOP) plasticizer per hundred parts of resin and resins of differing intrinsic vis cosity ranging from 0.80 to 1.18. It can be seen that the tensile strength and elon gation at break increase with increasing molecular weight. Figures 1 and 2 show these points graphically. The suggestions for the use of our products are based on tests believed to be reliable. However, due to vari ations in consumer handling and methods of compounding, we do not guarantee the results to be obtained, nor do we assume any liability for the use by a consumer of any materials or process in violation of common law or patent rights. l 5-1-65 AD 6EHC 000596 FIGURE 1. EFFECT OF MOLECULAR WEIGHT ON TENSILE STRENGTH * TENSILE STRENGTH, PSI ELONGATION AT BREAK, % FIGURE 2. EFFECT OF MOLECULAR WEIGHT ON ELONGATION ) 2 000O7 ' TEMPERATURE, F Calendering temperatures increase from a 300 to 330F level with a 0.80 viscosity resin to a 330 to 360F level for the 1.18 viscosity resin, as shown in Figure 3. FIGURE 3. EFFECT OF MOLECULAR WEIGHT ON CALENDERING TEMPERATURE Higher processing temperatures tend to create resin instability problems if the processing cycle is of long duration. A compromise must often be made between the molecular weight resin selected and the processing technique. The higher molecular weight resins are used in extrusions of flexible tubing, welt ing, electrical components, garden hose, and calendered film which require short dwell times at the elevated processing temperatures. Intermediate molecular weight resins are used in film and sheet, coated fabrics apd rigid applications. Low mole cular weight resins are used in fluidized bed coatings, phonograph records and in jection molded parts.