| 11. |
- Andersson, Per, et al.
(författare)
-
Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of polyethylene
- 1973
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 44:6, s. 2601-2605
-
Tidskriftsartikel (refereegranskat)abstract
- The pressure dependence of the specific heat of high‐density polyethylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300 K and in the pressure range 0–25 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, the values at 25 kbar being higher by factors of 2.75 and 2.77, respectively, than those at atmospheric pressure. The specific heat decreases, most strongly so at low pressures, and its value at 25 kbar is 0.80 times that at atmospheric pressure. The thermal conductivity of low‐density polyethylene was determined as a function of pressure. Its value at 25 kbar was found to be 2.19 times that at atmospheric pressure. The difference in conductivity response to pressure between the two varieties is given a simple theoretical interpretation.
|
|
| 12. |
- Andersson, Per, et al.
(författare)
-
Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of some polymers
- 1975
-
Ingår i: Journal of Polymer Science Polymer Physics Edition. - : Wiley. - 1542-9385 .- 0098-1273. ; 13:2, s. 243-251
-
Tidskriftsartikel (refereegranskat)abstract
- The pressure dependence of the specific heat of poly(methyl methacrylate), polystyrene, and atactic and isotactic polypropylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300°K and in the pressure range 0-37 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, while the specific heat decreases. The pressure dependencies are most pronounced at low pressures. The results are compared with other experimental results and with theoretical calculations.
|
|
| 13. |
- Andersson, Per, et al.
(författare)
-
Specific heat of solids at high pressures from simultaneous measurements of thermal conductivity and diffusivity
- 1972
-
Ingår i: High Temperatures-High Pressures. - 0018-1544 .- 1472-3441. ; 4:1, s. 101-109
-
Tidskriftsartikel (refereegranskat)abstract
- A method of determining the specific heat of solids at high pressures, from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry, is described. Results are reported for polytetrafluoroethylene (Teflon) in the range 0-30 kbar at 300 K. With increasing pressure both the thermal conductivity and diffusivity increase strongly and approximately linearly, while the specific heat decreases, most strongly at low pressures.
|
|
| 14. |
- Andersson, Per
(författare)
-
Thermal conductivity and heat capacity of cyclohexane under pressure
- 1978
-
Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 39:1, s. 65-68
-
Tidskriftsartikel (refereegranskat)abstract
- The transient hot-wire technique was used to determine the thermal conductivity, λ, and the specific heat capacity per unit volume, ρcp, of cyclohexane up to 1.5 GPa in the range 120–340 K. The measurements were carried out in a piston-cylinder apparatus, 45 mm in internal diameter, cooled by liquid nitrogen. There is only a small (6%) increase in λ on freezing, while there is an increase by a factor of two corresponding to the plastic→ normal crystal transition. The variation of λ with temperature (T) at P = 0.03 GPa is d(lnλ)/dT = −2.2×10−3K−1 for the liquid and d(ln λ)/dT = −0.9×10−3K−1 for the plastic crystalline phase. In the normal crystal phase an approximate T−1 dependence is observed. Within each of the phases λ increases linearly with pressure, and the slope of λ (P) is smallest in the plastic crystal phase. The existence of a recently reported new high pressure phase is evident from conductivity data. Qualitative ρcp -results are reported.
|
|
| 15. |
- Andersson, Per
(författare)
-
Thermal conductivity and heat capacity of cyclopentane in the range 100–300 K and up to 2·1 GPa
- 1978
-
Ingår i: Molecular Physics. - : Taylor & Francis. - 0026-8976 .- 1362-3028. ; 35:2, s. 587-591
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity, λ, and the specific heat capacity per unit volume, ρCp, of cyclopentane were determined in the range 100–300 K and up to 2.1 GPa. The transient hot-wire technique was used, and the experiments were carried out in a piston-cylinder apparatus. The λ values for the liquid and the two plastic crystalline phases are quite similar, while there is a strong increase corresponding to the plastic → normal crystal transition. In the normal crystal phase a T-1 dependence is observed, in contrast to the small variations of λ with temperature in the other phases. The pressure dependence of λ for the two plastic crystal phases shows a behaviour similar to that of the compressed liquid. Approximate ρCp data are reported. An extended phase diagram for cyclopentane is given.
|
|
| 16. |
- Andersson, Per, et al.
(författare)
-
Thermal conductivity of solids under pressure by the transient hot wire method
- 1976
-
Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 47:2, s. 205-209
-
Tidskriftsartikel (refereegranskat)abstract
- An electronic circuit has been constructed which delivers constant power to a nickel wire also functioning as a resistance thermometer. The temperature increase versus time, t, is linear in ln t, and the coefficient of slope directly yields the thermal conductivity of the medium surrounding the wire. Systematic errors due to finite time, wire length, and lateral extension of the medium and due to plastic deformation of the wire are analyzed. Temperatures are sampled automatically, and the digital data are reduced by means of an on-line desk calculator. The thermal conductivities of AgCl and polytetrafluoroethylene have been measured up to 10 kilobar.
|
|
| 17. |
- Andersson, Per
(författare)
-
Thermal conductivity of some rubbers under pressure by the transient hot-wire method
- 1976
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 47:6, s. 2424-2426
-
Tidskriftsartikel (refereegranskat)abstract
- The transient hot-wire method was used to determine the effect of fillers on the thermal conductivities of different rubbers in the pressure range up to 0.2 GPa at 300 K. The fillers, carbon black and ZnO, both strongly increase the absolute conductivity values but the relative pressure reponses are only slightly affected. The thermal conductivities increase linearly with pressure, and the pressure coefficients are in the range 1.0-1.6 per GPa for all the rubbers studied. The thermal conductivity of a filled rubber is analyzed in terms of contributions from the filler and the pure rubber. The experimental results show a stronger increase in conductivity with the percentage of filler than predicted by theory.
|
|
| 18. |
- Andersson, Per, et al.
(författare)
-
Thermal conductivity of Teflon at high pressures
- 1975
-
Ingår i: High Temperatures-High Pressures. - 0018-1544 .- 1472-3441. ; 7:5, s. 551-553
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity of different qualities of polytetrafluoroethylene, in the form of cylindrical specimens, was measured up to 3 GPa at room temperature by a steady-state method. A transient hot-wire method was also employed at pressures up to 1 GPa. With the exception of a recent investigation, reasonable agreement with previous work was obtained.
|
|
| 19. |
|
|
| 20. |
|
|
