A new differential scanning calorimetry based approach for the estimation of thermal conductivity of polymer solids and melts

Khanna, Y. P.; Taylor, Tom; Chomyn, Georgette

doi:10.1002/pen.760281604

Cited by 19 publications

(8 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A cylindrical model of the pulse decay method was also explored in [59]. In addition to the above-described methods various other methods exist, including hot wire methods (similar to the heated thermocouple method, but cylindrical in assumed geometry) [60] [47], Differential Scanning Calorimetry (DSC) operational methods [61] [62] [63], surface measurement techniques [64] [65] [66], and MRI thermometry methods [67]. …”

Section: Thermal Properties Of Biomaterialsmentioning

confidence: 99%

Review of biomaterial thermal property measurements in the cryogenic regime and their use for prediction of equilibrium and non-equilibrium freezing applications in cryobiology

Choi

Bischof

2010

Cryobiology

View full text Add to dashboard Cite

It is well accepted in Cryobiology that the temperature history and cooling rates experienced in biomaterials during freezing procedures correlate strongly with biological outcome. Therefore, heat transfer measurement and prediction in the cryogenic regime is central to the field. Although direct measurement of heat transfer can be performed, accuracy is usually achieved only for local measurements within a given system and cannot be readily generalized to another system without the aid of predictive models. The accuracy of these models rely upon thermal properties which are known to be highly dependent on temperature, and in the case of significant cryoprotectant loading, also on crystallized fraction. In this work we review the available thermal properties of biomaterials in the cryogenic regime. The review shows a lack of properties for many biomaterials in the subzero temperature domain, and especially for systems with cryoprotective agents. Unfortunately, use of values from the limited data available (usually only down to −40 °C) lead to an underestimation of thermal property change (i.e. conductivity rise and specific heat drop due to ice crystallization) with lower temperatures. Conversely, use of surrogate values based solely on ice thermal properties lead to an overestimation of thermal property change for most biomaterials. Additionally, recent work extending the range of available thermal properties to −150 °C has shown that the thermal conductivity will drop in both PBS and tissue (liver) due to amorphous/ glassy phases (vs. ice) of biomaterials with the addition of cryoprotective additives such as glycerol. Thus, we investigated the implications of using approximated or constant property values versus measured temperature-dependent values for predicting heat transfer in PBS (phosphate buffered saline) and porcine liver with and without cryoprotectants (glycerol). Using measured property values (thermal conductivity, specific heat, and latent heat of phase change) of porcine liver, a standard was created which showed that values based on surrogate ice properties underpredicted cooling times, while constant properties (i.e. based on limited data reported near the freezing point) over-predicted cooling times. Additionally, a new iterative numerical method that accommodates non-equilibrium cooling effects as a function of time and position (i.e. crystallization vs. amorphous phase) was used to predict heat transfer in glycerol loaded systems. Results indicate that in addition to the increase in cooling times due to the lowering of thermal © 2009 Elsevier Inc. All rights reserved.Correspondence to: John C. Bischof. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors ma...

show abstract

Section: Thermal Properties Of Biomaterialsmentioning

confidence: 99%

Review of biomaterial thermal property measurements in the cryogenic regime and their use for prediction of equilibrium and non-equilibrium freezing applications in cryobiology

Choi

Bischof

2010

Cryobiology

View full text Add to dashboard Cite

show abstract

“…Other methods include the use of oscillatory heating 6 and melting point standards. 7 Several optically based techniques have also been used, such as the photothermal probe beam deflection 8 and pulsed photothermal radiometry, 9 which appear to be best suited for thin film samples.…”

Section: Introductionmentioning

confidence: 99%

Measurement of thermal diffusivity in polymer melts using forced Rayleigh light scattering

Venerus

Schieber

Iddir

et al. 1999

J. Polym. Sci. B Polym. Phys.

View full text Add to dashboard Cite

Thermal diffusivity measurements on three polymer melts were made using the Forced Rayleigh Light Scattering technique. The polymers, which were tested at room temperature where they are in the molten state, included a polydimethylsiloxane and two polyisobutylenes. The optical setup and procedures developed in this study to conduct thermal Forced Rayleigh Light Scattering experiments are shown to be capable of producing thermal diffusivity data with a high degree of accuracy and precision. From measurements on a reference fluid (ethanol), experimental error was estimated to be no greater than 2%, and could be reduced to less than 1% by appropriate design of a series of experiments. Discrepancies of 4 and 14% in thermal diffusivity data on the polymer samples between measured values and those found in the literature were observed. It is suggested that these deviations are attributable to either sample variations or to errors in the techniques used in previous investigations. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1069–1078, 1999

show abstract

“…These chemicals were selected due to variations in their thermal conductivity while their heat capacity and thermal expansion remained practically constant in the range of temperature between the melting and crystallization temperature of the respective polymers. The experimentally measured values of thermal conductivity, using the method of Khana et al,19 are shown in Figure 1. From here, it is observed that overall KBr has higher values of thermal conductivity than AgCl.…”

Section: Resultsmentioning

confidence: 99%

“…Thermal conductivity measurements were made in a differential scanning calorimeter (DSC) Perkin‐Elmer 7 using the method developed by Khana et al19 In order to calculate thermal conductivity, quartz was used as the reference compound and samples were prepared with the same dimensions as the quartz reference using a hydraulic press. Thermal conductivity was then calculated as in Khana et al19 using where K x and K s are the values of thermal conductivity of sample and reference respectively, M x and M s are the slopes of the corresponding melting endotherms.…”

Section: Methodsmentioning

confidence: 99%

Heterogeneous nucleation of nylon 6 and PET with selected inorganic compounds

Martínez-Vázquez

Medellín‐Rodríguez

Phillips

et al. 2003

J of Applied Polymer Sci

View full text Add to dashboard Cite

ABSTRACT:The effect of several inorganic compounds in the heterogeneous nucleation of poly(ethylene terephthalate) (PET) and poly(caprolactam) (nylon 6) was studied. Six inorganic chemicals were specifically selected, on the basis of their crystal structure, basal lattice dimensions, and thermal properties, in order to study the effect of temperature in their nucleation capabilities. Considering that temperature is one of the most important variables involved during processing of thermoplastics, the impact of the nucleation ability of the intentionally added heterogeneities was studied in terms of thermal conductivity, thermal expansion, and heat capacity. Six inorganic chemicals, which crystallize in the cubic system, were selected considering that they had variations in one of the thermal properties while the others remained practically constant along the temperature range of interest. The results indicated that, at constant surface area, chemical compounds with lower overall values of thermal expansion and also those with overall higher values of heat capacity promote heterogeneous nucleation; the effect of heat capacity was, however, also found potentially related to a different intrinsic mechanism. The impact of thermal conductivity was not considered significant.

show abstract

A new differential scanning calorimetry based approach for the estimation of thermal conductivity of polymer solids and melts

Cited by 19 publications

References 9 publications

Review of biomaterial thermal property measurements in the cryogenic regime and their use for prediction of equilibrium and non-equilibrium freezing applications in cryobiology

Review of biomaterial thermal property measurements in the cryogenic regime and their use for prediction of equilibrium and non-equilibrium freezing applications in cryobiology

Measurement of thermal diffusivity in polymer melts using forced Rayleigh light scattering

Heterogeneous nucleation of nylon 6 and PET with selected inorganic compounds

Contact Info

Product

Resources

About