On theC p toC v conversion of solid linear macromolecules II

Pan, Robert; Nair, Manika Varma; Wunderlich, Bernhard

doi:10.1007/bf02057252

Cited by 118 publications

(37 citation statements)

References 19 publications

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“…Heat capacities Co were calculated for all the three sets of computations. The Cp to Cv and Cv to Cp conversions were made using the modified Nernst-Lindemann equation with an average A o value of 3.9 • 10-3 (K mol)/J [21]. Using 6 and 4 skeletal vibrations, the deviation of the calculated Cp from the experimental data of Table 2 was much higher than the experimental.uncertainty of perhaps • 5%.…”

Section: Heat Capacities Of Pdms and Pdesmentioning

confidence: 99%

The thermal properties of polysiloxanes poly(dimethyl siloxane) and poly(diethyl siloxane)

Varma‐Nair

Wesson

Wunderlich

1989

Journal of Thermal Analysis

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New measurements and literature data on polysiloxanes covering heat capacities, transition parameters, enthalpies, entropies and Gibbs energies are presented and critically reviewed. The ATHAS computation method is used to bring heat capacities into agreement with an approximate frequency spectrum. The various crystal and mesophases are discussed. The ATHAS (1990) recommended data are as follows: For poly(dimethyl siloxane) the glass transition is at 146 K with an increase in heat capacity of 29.24 J/(K mol). The completely crystalline sample melts at about 219 K with a heat of fusion of 2.75 kJ/mol. For poly(diethyl siloxane) the glass transition is at 135 K with an increase in heat capacity of 34.48 J/(K mol). The completely crystalline sample changes to a condis crystal at 206.7 K with a heat of disordering of 2.72 kJ/mol. The transition to a poorly characterized "viscous crystal" with thermodynamic properties close to the melt occurs at 282.7 K with an enthalpy of transition of 1.84 kJ/mol. Final fusion occurs'at 308.5 K and a small endotherm of about 231 J/tool. Tables of heat capacities, enthalpies, entropies and Gibbs energies are given from 0 K to 550 K.Of the poiysiloxanes only poly(dimethyl siloxane), PDMS, and poly(diethyl siloxane), PDES, have found major attention. In the 1980 ATHAS data bank of heat capacities of macromolecules [1] only few data on semicrystalline PDMS and PDES could be presented [2]. The follow-up analyses and fitting of the data in the solid state to approximate vibrational frequency spectra done with many other polymers [3] could not be carried out before because of lack of data and understanding of the phase behaviour. This paper, largely based on the experimental work of one of us (J.P.W.) [4] and the continuing A THA S collection of thermal data, brings PDMS and PDES into the group of close to 100 well characterized polymers [5].

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Section: Heat Capacities Of Pdms and Pdesmentioning

confidence: 99%

The thermal properties of polysiloxanes poly(dimethyl siloxane) and poly(diethyl siloxane)

Varma‐Nair

Wesson

Wunderlich

1989

Journal of Thermal Analysis

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“…The third term in Eq. (1) represents a difference between heat capacity at constant pressure C p and C v (C v = Debye term + Einstein term) and was suggested by Pan et al [14] for correlation of C p values for linear macromolecules. For large molecules the difference between C p and C v is less than 5% of the C p value [13], even at the melting point, and this difference is often neglected for large molecules.…”

Section: Computation Detailsmentioning

confidence: 95%

A similarity variable for estimating the heat capacity of solid organic compounds

Laštovka

Sallamie

Shaw

2008

Fluid Phase Equilibria

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“…The constant volume heat capacity C v , given by above equation, can be converted into constant pressure heat capacity C p using the NernstLindemann approximation 16,17 ;…”

Section: Calculation Of Specific Heatmentioning

confidence: 99%

Vibrational Spectroscopic and Thermodynamic Investigation of Poly (vinyl butyral)

Ansari¹,

ParvejAli²,

Srivastava³

et al. 2016

Orient. J. Chem

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A detailed study was performed to investigate the normal modes of vibration and their dispersions in poly (vinyl butyral) by using Urey-Bradley force field and Wilson's GF matrix method as modified by Higgs. It provides detailed interpretation of FTIR. Characteristic feature of dispersion curves such as regions of high density-of-states, repulsion and character mixing of dispersion modes are discussed. Predictive values of heat capacity as a function of temperature between 0-350 K have been evaluated.

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On theC p toC v conversion of solid linear macromolecules II

Cited by 118 publications

References 19 publications

The thermal properties of polysiloxanes poly(dimethyl siloxane) and poly(diethyl siloxane)

The thermal properties of polysiloxanes poly(dimethyl siloxane) and poly(diethyl siloxane)

A similarity variable for estimating the heat capacity of solid organic compounds

Vibrational Spectroscopic and Thermodynamic Investigation of Poly (vinyl butyral)

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