Effective thermal conductivity and coefficient of linear thermal expansion of high-density polyethylene — fly ash composites

Abstract

As the disposal of fly ash (FA) poses a serious problem in terms of land use and potential environmental pollution, there exists a global interest for its utilization. Utilization of fly ash as filler material in polymer composites is considered important from both economic and commercial point of view. In this communication, the effective thermal conductivity and coefficient of thermal expansion (CTE) of composites synthesized with fly ash filler embedded in high-density polyethylene (HDPE) matrix is investigated. Incorporation of fly ash in HDPE enhances both the thermal stability and the effective thermal conductivity of the composites. CTE, however, significantly decreases as the FA content increases in HDPE. Effective thermal conductivity for HDPE containing 70-volume fraction (%) fly ash becomes almost twice than that for unfilled HDPE. Results on both the effective thermal conductivity and CTE of HDPE/FA composites have been discussed in light of various theoretical models. Our analysis indicates formation of conductive channels of FA particulates in HDPE, which causes rapid enhancement in the effective thermal conductivity of the HDPE/FA composites. We also confirm the importance of the role of the interphase volume and the strength of the polymer -filler interactions to successfully predict the CTE of HDPE/FA composites.

Industrially viable technique for the preparation of HDPE/fly ash composites at high loading: Thermal, mechanical, and rheological interpretations

“…TGA graph (Figure and Table ) showed increase in char residue with FA loading which is attributed to good agreement with the actual loading. Similar behavior of FA has also been reported by Baglari et al . and Bonda et al .…”

Enhanced Thermal Conductivity and Dielectric Properties of Iron Oxide/Polyethylene Nanocomposites Induced by a Magnetic Field

“…For instance, the thermal conductivity of the M-Fe 3 O 4 /LDPE composites is 0.461 W m −1  K −1 at 7.0 vol.% concentration, higher than that of the Fe 3 O 4 /LDPE composites (0.384 W m −1  K −1 ), and this value is superior to that of many previous reports 15, 18, 20, 26–28 . As shown in Table 1, the thermal conductivity of our composites is larger than that of the high-density polyethylene/fly-ash (HDPE/FA) composites containing 10 vol.% FA (≈0.41 W m −1  K −1 ) 27 . It should be pointed out that the filler content of the M-Fe 3 O 4 /LDPE composites is smaller than that of other literature materials, with better flexibility.

Figure 3Thermal conductivity of the Fe 3 O 4 /LDPE and M-Fe 3 O 4 /LDPE composites corresponding to thermal enhancements.

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“…As shown in Table 1, the thermal conductivity of our composites is larger than that of the high-density polyethylene/fly-ash (HDPE/FA) composites containing 10 vol.% FA (≈0.41 W m −1  K −1 ) 27 . It should be pointed out that the filler content of the M-Fe 3 O 4 /LDPE composites is smaller than that of other literature materials, with better flexibility.

Figure 3Thermal conductivity of the Fe 3 O 4 /LDPE and M-Fe 3 O 4 /LDPE composites corresponding to thermal enhancements.

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Al2Mo3O12/polyethylene composites with reduced coefficient of thermal expansion

“…Geomembranes and pipes for water or natural gas transmission/distribution are some examples of PE applications where the huge CTE (*10 -4 K -1 ) or migration of volatile organic components (VOCs) can induce material damage or lead to poor performance [32,33]. The list of dispersed phases studied for the purpose of reduction of CTE of PE is extensive and includes clays, CaCO 3 , Si, fly ash, CeO 2 , Sr 2 Al 2 SiO 7 , just to mention a few [34][35][36][37][38][39], but, so far, has not included thermomiotics or low CTE materials.…”