The linear rheological responses of wedge‐type polymers |
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Authors: | Miao Hu Yan Xia Christopher S Daeffler Jinhua Wang Gregory B McKenna Julia A Kornfield Robert H Grubbs |
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Institution: | 1. Department of Chemical Engineering, Texas Tech University, Lubbock, Texas;2. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California |
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Abstract: | The linear rheological responses of a series of specially designed wedge‐type polymers synthesized by the polymerization of large molecular weight monomers have been measured. These wedge polymers contained large side groups which contained three flexible branch chains per polymer chain unit. The master curves for these polymers were obtained by time temperature superposition of dynamic data at different temperatures from the terminal flow regime to well below the glass transition temperature, Tg. While these polymers maintained a behavior similar to that of linear polymers, the influence of the large side group structure lead to low entanglement densities and extremely low rubbery plateau modulus values, being near to 13 kPa. The viscosity molecular weight dependence was also somewhat higher than that normally observed for linear polymers, tending toward a power law near to 4.2 rather than the typical 3.4 found in entangled linear chains. The glassy modulus of these branched polymers is also found to be extremely low, being less than 100 MPa at Tg ?60 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 899–906 |
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Keywords: | branched glassy polymers macromonomers rheology viscoelastic properties viscosity |
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