Theoretical study of transport of heat through amorphous helical polymers

29-33A study of transport of heat through non-conducting amorphous helical polymers is presented. Predominant phonon scattering processes have been identified on the basis of general structural features and the effect of temperature on these. Accordingly, relations have been deduced for the dependence of the thermal conductivity λ on temperature T. It is shown that the glass transition temperature Tg of polymers can also be predicted through the conductivity trends, estimated values of <i style="mso-bidi-font-style: normal">Tg of PMMA, PIB and PTFE are quite close to the reported ones. Present study reveals that the helical polymers fall in 'group A' of the classification of linear polymers proposed recently by the authors (Polymer 37, (1996), 231). Calculated values of λ, of five different isotropic polymers viz. PIB, PTFE, PCTFE, PET and PMMA, over a wide range of temperature (90- 370 K), are in excellent agreement with the available experimental data (maximum deviation is 4%). Proposed theory also explains the effect of extrusion on the thermal conductivity. Theoretically computed values of thermal conductivities of extruded PMMA in the <span style="font-size:11.0pt;line-height:115%;font-family:Calibri;mso-fareast-font-family: Calibri;mso-bidi-font-family:" times="" new="" roman";color:black;mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">draw direction All and in the perpendicular to the draw direction λ<span style="font-size:11.0pt;line-height:115%;font-family:Arial;mso-fareast-font-family: Calibri;color:black;mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:AR-SA">┴<span style="font-size:11.0pt; line-height:115%;font-family:Calibri;mso-fareast-font-family:Calibri; mso-bidi-font-family:" times="" new="" roman";color:black;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"=""> agree well with the reported experimental values. Maximum deviation being 2%.</span

A theoretical study of self-diffusion, viscosity and Schmidt number of inert liquids and their temperature dependence

15-21<span style="font-size:16.0pt;mso-bidi-font-size: 11.0pt;line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";color:black;mso-ansi-language:en-in;mso-fareast-language:="" en-us;mso-bidi-language:hi"="" lang="EN-IN">A statistical theory for transport or mass and momentum through atomic liquids is presented. Both the characteristic features of liquid phase viz. the strong correlations among the atoms over smaller distances and high temporal disorder have been incorporated in the development of theory. Relations been developed for the coefficient of self diffusion D and coefficient of viscosity <span style="font-size:16.0pt; mso-bidi-font-size:11.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-us;mso-bidi-language:hi"="" lang="EN-IN">η. An explicit expression for Schmidt number Sc = symbol has also been derived. For the first time, the temperature dependence or Schmidt number in the liquid phase has been studied. Calculated value or D. η and Sc or neon. argon. Krypton and xenon over a wide range of temperature (Tm to 0.9 Tc are in good agreement with the reported experimental data. In fact Sc is a  true index of strength of atomic correlations, hence its temperature dependence reflects the gradual loss or order with the rise in temperature in liquid phase. It is found that for inert liquids the three quantities studied in the present work correspond very closely if values or properties at the melting  and melting temperatures are used as reducing parameters.</span