Thesis
The influence of extrusion processing and formulation on form-stable phase change material
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/107036
Abstract
There is a need in light-frame wood construction to develop mechanisms for thermal storage to lower energy demand and/or shift peak energy consumption to off-peak energy consumption times. Phase change materials (PCM) have the ability to store significant latent thermal energy with minimal volume and mass requirements. One technical challenge is to contain the PCM during the liquid phase. Form stable PCMs have been suggested as one solution. In form stable PCMs, the PCM is blended with a polymer, of a higher melting point, that adds structural stability to the blend and encapsulates the PCM melt to prevent leakage. The objective of this study is to determine the effect of processing method on the morphology and thermomechanical properties of three formulations of HDPE/paraffin blend. Form stable phase change materials consisting of 75/25, 60/40, and 50/50 blends of paraffin (octadecane)/high density polyethylene (HDPE) were produced at three different extrusion processing speeds and tested for leakage, thermal conductivity, latent heat storage capacity, storage modulus and dispersion. Paraffin with a melt temperature of 28°C was chosen as the PCM with HDPE as the containment polymer with higher melt temperature of 130°C. Thermal conductivity, measured by a KD2-Pro, of the blends increased (.330, .336, .358 W/mK at 100 rpm) with increasing amounts (25, 40, 50% respectively) of HDPE (the more thermally conductive material), attributing to good dispersion between the two materials. As characterized by DSC, latent heat storage capacity of the blends within the desirable range (25°C to 35°C) increased (98, 116, 153 J/g) with increasing amounts (50, 60, 75% respectively) of paraffin. Leakage of paraffin was measured by placing form stable PCM samples in solvent baths, recognizing that in situ leakage in building applications would be much less. Samples that were submerged for 10 hours showed percentage of total paraffin losses to be 38%, 36% and 28% for the formulations of 75/25, 60/40 and 50/50 paraffin/HDPE, respectively. While the morphology of the blend does allow pathways for some paraffin movement in a solvent bath, the practical amounts of leakage that might occur in a building product application have yet to be determined.
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Details
- Title
- The influence of extrusion processing and formulation on form-stable phase change material
- Creators
- Gregory Dale Estep
- Contributors
- Donald A. Bender (Degree Supervisor)Long Jiang (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525102301842
- Language
- English
- Resource Type
- Thesis