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The Case of the Missing Glass Transition G. B. McKenna, Texas Tech University

The Case of the Missing Glass Transition G. B. McKenna, Texas Tech University. Glasses are important to our everyday life and understanding their formation remains one of Nature’s mysteries. One root controversy in the field is the importance of the Kauzmann paradox to this understanding.

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The Case of the Missing Glass Transition G. B. McKenna, Texas Tech University

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  1. The Case of the Missing Glass TransitionG. B. McKenna, Texas Tech University • Glasses are important to our everyday life and understanding their formation remains one of Nature’s mysteries. One root controversy in the field is the importance of the Kauzmann paradox to this understanding. • The Kauzmann paradox results because the extrapolated entropy of the liquid falls below that of the crystalline solid at a finite temperature in violation of the “third” law of thermodynamics • The “ideal” glass transition has been postulated to be a second order phase transition at the Kauzmann temperature and resolves the paradox. • In our work we have performed novel calorimetric experiments on mixtures of poly(a-methyl styrene) with its pentamer and found two important things. • 1. The heat capacity is independent of the concentration. • 2. The entropy of the 100% polymer does not exhibit a second order transition as much as 130 K below the Kauzmann temperature. • This result is contrary to expectations based on “ideal” glass transition theories. Figure 1. Specific heat of poly(a-methyl styrene)/ Penatmer mixtures as a function of polymer concentration. Figure 2. Excess entropy vs. temperature for 100% polymer showing no evidence of an ideal glass transition to well below the Kauzmann temperature.

  2. Broad Accomplishments-FY2003NSF Grant DMR-0070552 • Education and Outreach • Project results presented at national and international meetings • 3M Company, Minneapolis, MN, October 2002 (invited presentation by PI) • Society of Rheology in October 2002.(oral presentations by Y.Zheng, graduate student;M. Alcoutlabi, post-doc) • AICHE annual meeting, November 2002. (oral presentation by PI) • Materials Research Society in December 2002. (invited presentation by PI) • APS in March 2003 [oral presentation by Y. Zheng (graduate student); poster presentations by R.D. Priestley (undergraduate student)and and M. Alcoutlabi, (post-doc)] • Deformation Yield and Fracture of Polymers, Cambridge, UK (oral presentation by PI) • Society of Plastics Engineers ANTEC in May 2003 (oral presentation by PI) • Project results presented at one regional meeting • NaTex in April 2003 (poster presentations by Y. Zheng, M. Alcoutlabi, L. Banda, graduate student and D. Huang, Post-doc) • Project results presented at U.S. and International Universities and National Labs by PI • University College, Dublin, Ireland, April, 2003 • University of Utah, May, 2003 • National Institute of Standards and Technology, May, 2003 • Air Force Research Laboratory, May, 2003 • Publication • 2 manuscripts published (Macromolecules, 36, 2387 (2003); J. Chem. Phys., 119, 3590 (2003)) • 3 proceedings publications • 1 manuscripts in review (J. Polym. Sci. Physics Ed.)

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