Design of thermal hybrid composites based on liquid crystal polymer and hexagonal boron nitride fiber network in polylactide matrix

Abstract

Development of high thermally conductive and electrically insulative composites is of interest for electronic packaging industry. Advancements in smaller and more compact electronic devices required improvements in packing materials, including their weight, thermal conductivity, and electrical resistivity. In addition, with the increasing environmental awareness, the usage of green (bio‐based) alternatives was equally important. In the present study a hybrid based on fibers of highly concentrated hexagonal boron nitride (hBN) in liquid crystal polymer (LCP) matrix were fabricated. These hybrids were formed by arranging hBN platelets into LCP fiber form to reach high filler concentration and then randomly mix it in polylactide (PLA) matrix. With appropriate filler interaction within the hybrid, thermal conductivity similar to that of pure fiber could be achieved. Filler interaction may be tailored by optimizing the fibers aspect ratio. This study demonstrated the effect of random fillers in fibers shape in increasing the overall thermal conductivity of PLA polymeric hybrid using hBN and LCP fibers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 457–464

A review on high thermally conductive polymeric composites

“…From previous works on high thermally conductive composites filled with thermally conductive hexagonal boron nitride (hBN) platelets, the composite K eff presented direct and sensitive relations with the filler content as well as filler particle percolation. [51][52][53][54] The K eff of about 3.5 Wm À1 K À1 , which is about 9-times that of the neat polymer, has been reported for 33.3 vol% hBN-Polyamide (PA) composites. [54] However, achieving higher K eff by a further increase of the filler content would be challenging, as it would result in processing difficulties, high density, low mechanical properties, and high material cost.…”

“…Moreover, the achieved K eff of 3.5 Wm À1 K À1 at 33.3 vol % hBN loading is significantly less than the thermal conductivity of hBN micro platelets with reported in-plane thermal conductivity of 300 Wm À1 K À1 and out-plane thermal conductivity of 30 Wm À1 K À1 . [53] This suggests the need to study the heat transfer mechanism in polymer composites. This requires identifying the potential thermal barriers and possible limitations against a further increase of the composite k eff , closer to the filler/s thermal conductivity.…”

Poly(lactic acid)‐based nanocomposites

“…They observed enhanced thermal and electrical conductivity of the polymer matrix. They contend that this hybrid is a green alternative that may be used in electrical devices …”

Recent Advances and Opportunities for Cellulose Nanocrystal-Based Liquid Crystalline Polymer Hybrids and Composite Materials

“…Over the past two decades, environmental studies have made it apparent that commercially relevant synthetic liquid crystalline polymers (LCPs) have detrimental impacts on the marine and terrestrial environments. , These escalating environmental issues including the widespread accumulation of plastic debris, continuous depletion of fossil reserves, and global climate change have necessitated comprehensive research on the production of bio-based LCPs . These bio-based LCPs reduce greenhouse gas (GHG) emissions and improve energy security. , …”