Ortho-therphenyl (OTP) is a well known glassformer, but when used in experiments, it is often mixed with other chemicals f.x. ortho-phenylphenol OPP), due to experimental difficulties with pure OTP. When mixed in the weight ratio 67 % OTP and 33 % OPP, Takahara et al. (1999) determined the mixture to have a Prigogine-Defay ratio around 1.2 and it’s believed that OTP is a simple liquid. This characteristic makes the OTP-OPP mixture interesting. Throughout this article, we will investigate the OTP-OPP mixture, and examine the melting point, the isobaric heat capacity and the glass transition temperature in different mixture proportions. We investigate, if the “⅔-rule”, which says Tg = ⅔Tm, can be applied to the mixture. By using Differential Scanning Calorimetry (DSC), we will determine the melting point for the different mixtures, and compare these data with a theoretically calculated melting point curve. In addition, we use Heat Rate Analysis (HRA) to measure the isobaric heat capacity and glass transition temperature. Our results show, that OTP-OPP mixtures qualitatively follow the theoretical melting point curve. We were not able to determine the melting point for mixtures with a high amount of OPP, since these mixtures did not crystallize at temperatures far below the assumed Tm. We conclude that the OTP-OPP mixture does not abide the “⅔-rule”, but mixtures with 80-100 % OTP shows a correlation. Further experiments are necessary to be able to determine or dismiss a correlation between Tg and Tm.
|Uddannelser||Basis - Naturvidenskabelig Bacheloruddannelse, (Bachelor uddannelse) Basis|
|Udgivelsesdato||20 jun. 2011|
- Heat Rate Analysis
- Differential Scanning Calorimetry