Effect of polar solvents on dynamic moduli of concentrated solutions of polyethylacrylate

✍ Scribed by N. Nakajima; J. P. Varkey

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 244 KB
• Volume: 69
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980829)69:9<1727::aid-app6>3.0.co;2-d

✦ Synopsis

There have been many investigations on the effect of solvents on the dynamic moduli of concentrated polymer solutions. However, most of the polymers investigated were nonpolar, such as polystyrenes and polybutadienes. Moreover, the samples were usually model polymers of very narrow molecular weight distribution and were either linear or branched star. Our investigation was on a commercial polymer, which is polar and has long branches but is ''gel free.'' The solvents used were polar plasticizers. This study was motivated by the frequent observation that a small addition of plasticizers has little effect on the rubbery modulus or has an unexpectedly large reduction of the rubbery modulus, depending on a polymer-plasticizer pair. This work examines concentrated solutions of polyethylacrylate and three plasticizers (DBP, DHP, and DOP) at concentrations above 50% for DBP and DHP and above 80% for DOP. DOP did not dissolve the rubber at the lower concentrations. The temperature range was 30 -150°C, and the frequency range was 10 Ϫ2 -10 2 rad/s. The time-temperature correspondence was applicable over the entire range of observation. The rubbery modulus was found to be independent of the plasticizer type at all concentrations. With dilution to 90% of polymer there was only small decrease of the modulus, and with further dilution the modulus decreased with a slope of 1.8 in the double-logarithmic plot of the modulus against concentration.