https://doi.org/10.1371/journal.pone.0170523.g009, In a model proposed by Agari [45], the Maxwell-Eucken model is modified by combining with a thermal conduction model which accounts for the effect of conductive chain formation in composites. [18], BN nanoplatelets were first covalently functionalized with hyperbranched aromatic polyamide (HBP). Assuming the linear increase of TC with the filler content when the filler content is below 15 vol%, the TC of the PP/BN composites with 12 vol% BN is estimated to be ~0.48 W/mK, which is very close to our results. introduced two different types of surface treated BN into the PP matrix: pristine and covered with silane coupling agent (−3-amino-propyl-3-ethoxy-silane-APTES). https://doi.org/10.1371/journal.pone.0170523.g004. A hybrid has been conceived as a mixture of two or more raw materials with own intrinsic properties and different shape and size (“A + B + shape + scale”) to enhance or diminish physical, mechanical, thermal and electrical properties, as stiffness or strength, and also to manipulate the percolation limit [64]. No, Is the Subject Area "Boron" applicable to this article? In the case of composites including an individual filler, the highest TC value (28 W/mK) was achieved with 80% in wt. They found that the TC of PP composites filled with surface-modified h-BN was up to 2 times as compared with the composites filled with pristine h-BN. As described in literature, heat transfer in polymer composites can be explained by the propagation of phonons or flow of lattice vibrational energy [20, 24]. Compared to the polypropylene (PP) composites filled with pristine BN at the same filler content, thermal conductivity was much higher for those filled with both functionalized BN (f-BN) and maleic anhydride grafted PP (PP-g-ma) due to the improved filler dispersion and better interfacial filler-matrix compatibility, which facilitated the development of more thermal paths. Thermal conductivity of the polypropylene is increased from 0.27 up to 2.5 W/ (m K) with … The filler functionalization (i.e., the introduction of functional group on filler surface) and the addition of compatibilizer in polymer/particles mixtures, have been considered a useful approach for developing the compatibility between the two phases, and consequently for improving the dispersion and the interfacial interaction. Login to your personal dashboard for more detailed statistics on your publications. In conclusion, in order to successfully employ the thermal conductive particles in composites for heat management applications, the realization of a conductive pathway through the particles (shown in Figure 3) has to be attained through optimal filler dispersion, good interfacial adhesion between filler-matrix and properly contact between particles. The pH value of the solution was adjusted to 8.5 by using NaOH solution (0.1 mol/L). SEM characterization also confirms the uniform dispersion of the fillers in the polymer matrix without the formation of voids (Fig 4e and 4f). In fact, when the orientation has been induced in the polymer, its TC became higher in the direction of a molecular orientation and lower in a direction normal to the orientation [31]. School of Renewable Energy, North China Electric Power University, Beijing, China, * E-mail: duxz@ncepu.edu.cn (XZD); jun.lin@ncepu.edu.cn (JL), Affiliation As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. The TCs of BN and PP are set to 300 W/mK [44] and 0.22 W/mK for calculation. Recently, mussel-inspired approach has been widely employed to modify various materials with self-polymerized dopamine coatings, which was found to be able to adhere to almost all kinds of substrates [32–35]. Therefore, non-covalent functionalization of BN was also attempted in the past. https://doi.org/10.1371/journal.pone.0170523, Editor: Yogendra Kumar Mishra, Institute of Materials Science, GERMANY, Received: October 7, 2016; Accepted: January 5, 2017; Published: January 20, 2017. The samples were equilibrated for 10 min at 20°C before being heated at a rate of 5°C/min to 100°C. https://doi.org/10.1371/journal.pone.0170523.g001. This meant that nanoscale unique properties could not be reproduced easily on the macroscale probably for non-continuum effects at filler-polymer interfaces [51]. Compared to that of neat PP, the incorporation of 25 wt% (12 vol%) f-BN alone showed an enhancement of only 1.95 times in composite TC, while there was a TC enhancement of 2.14 times for the PP/BN composites with the same filler content. For the same reason, processes like extrusion, injection molding and foaming, by causing an orientation of the polymeric molecular chains, could determine an increase of TC in the same direction of the inferred one. [60] functionalized the surfaces of micrometric BN with a thin layer of polydopamine coatings (f-BN). The composite TC is calculated by Eq (1), Finally, a nearly linear temperature dependence without any detectable plateau of the TC of PP copolymer was observed by Barucci et al. This series is referred to as “PP/PP-g-ma/f-BN” composites. 51406052, 51303051), the National Basic Research Program of China (No. in the range of temperature from 0.1 to 4 K [28]. In details, below the glass temperature, as the temperature grew up, the TC of the amorphous remained the same or increased with temperature (probably for the effect of raising chain mobility), while for crystalline the TC initially remained the same and then diminished. Thermal conductivity is a material property that describes ability to conduct heat. The effect of acting pressure on TC of polypropylene seemed to be always positive, probably for the induced stress in a longitudinal direction that led to anisotropy of the tested feature. Yes Yet, higher TC measurements were verified in the presence of microparticles, in particular with layered shape (talc); the same results have never been reached by adding nanoparticles. Since the polymeric structure order of the amorphous is lower than of the crystalline, the related thermal behaviour of the former has been expected to be lower compared to the latter, and also TC temperature dependence has changed in different ways depending on substance state. Yet, the use of an extremely high percentage of reinforcement (approximately more than 30% in vol. (4-3). Discover a faster, simpler path to publishing in a high-quality journal. Fig. It could be found that the experimental heat capacities of PP/BN and PP/PP-g-ma/f-BN composites generally agree well with the calculation results. The addition of such non-covalently modified BN also resulted in the better filler dispersion and higher composite TC [27].