Foamed Phase Change Materials Based on Recycled Polyethylene/Paraffin Wax Blends

Abstract

Foamed phase-change materials (FPCMs) were prepared using recycled linear low-density polyethylene (LLDPE) blended with 30 wt.% of paraffin wax (PW) and foamed by 1,1′-azobiscarbamide. The protection of pores’ collapse during foaming process was insured through chemical cross-linking by organic peroxide prior foaming. This work represents one of very few attempts for a preparation of polymeric phase change foams without a use of micro-encapsulated phase change component leading to the enhancement of the real PCM component (PW) within a final product. The porous structure of fabricated foams was analyzed using micro-computed tomography, and direct observation, and reconstruction of the internal structure was investigated. The porosity of FPCMs was about 85–87 vol.% and resulting thermal conductivity 0.054–0.086 W/m·K. Differential Scanning Calorimetry was used to determine the specific enthalpies of melting (22.4–25.1 J/g) what is the latent heat of materials utilized during a heat absorption. A stability of samples during 10 heating/cooling cycles was demonstrated. The phase change changes were also investigated using the dynamic mechanical analysis from 0° to 65 °C during the 10 cycles, and the mechanical stability of the system and phase-change transition were clearly confirmed, as proved by DSC. Leaching test revealed a long-term release of PW (around 7% of its original content) from samples which were long term stored at temperatures over PW melting point. This is the usual problem concerning polymer/wax blends. The most common, industrially feasible solution is a lamination of products, for instance by aluminum foils. Finally, the measurement of the heat flow simulating the real conditions shows that samples containing PW decrease the energy passing through the sample from 68.56 to 34.88 kJ·m−2. In this respect, FPCMs provide very effective double functionality, firstly common thermal insulators, and second, as the heat absorbers acting through melting of the PW and absorbing the excessive thermal energy during melting. This improves the heat protection of buildings and reduces temperature fluctuations within indoor spaces.

Gamma Irradiation and the Radiation Shielding Characteristics: For the Lead Oxide Doped the Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers and the Polystyrene-b-Polyethyleneglycol-Boron Nitride Nanocomposites

“…In addition to all these features, their lightness also gives polymer composite materials superiority in many areas. For these reasons, polymer composite-based materials have been the focus point of scientific interest and active multidisciplinary and industrial research groups because of their interesting properties and potential [ 20 , 21 , 22 ]. In addition, many explorers have remarkably conducted polymer composite-based radiation-absorbing substances [ 23 , 24 , 25 , 26 , 27 ].…”

Recent Progress in Polyethylene‐enhanced Organic Phase Change Composite Materials for Energy Management

“…Alternatively, melt‐blending or hot pressing of PEs with the PCMs form a Shape‐Stabilised Phase Change Material (SSPCM), eliminating the need to encapsulate the PCMs [77] . Moreover, melt‐blending PCMs with PEs can enhance the thermal conductivity, lead to higher efficiency in absorbing or releasing heat [78,79] . Furthermore, scientists have investigated the approaches using carbon‐based materials for the enhancement of the PCMs’ thermal properties.…”

“…[77] Moreover, melt-blending PCMs with PEs can enhance the thermal conductivity, lead to higher efficiency in absorbing or releasing heat. [78,79] Furthermore, scientists have investigated the approaches using carbon-based materials for the enhancement of the PCMs' thermal properties. The extrusion or melt-blend method can be used to incorporate Graphite or Carbon Nanotubes, which increases the thermal stability and conductivity of PCM.…”

Influence of the Foaming Process on the Burning Behavior of the PET–PEN Copolymer

“…The polymer foam expands its applications in the areas of building insulation, aircraft, automobile, and packaging materials through its light weight, high heat resistance, and noise reduction characteristics. − Recently, it enlarged its uses to thermal energy storage, − energy harvesting, − and bioengineering. − …”