The influence of fillers with different particle sizes/distributions as well as their combinations on the thermal conductivity was systematically investigated at different concentrations. In their work, the authors measured the TC of semi-crystalline and amorphous polymers starting from room temperature and going up to melting temperature (for semi-crystalline polymers) or glass transition (for amorphous polymers). In details, for the examined semi-crystalline polymer, starting from room temperature and going up to melting point, an opposite trend of TC have been reported. By increasing filler loading, positive but not always satisfactory increases of TC in the respective compounds have been achieved. endobj A similar study was conducted by Cheewawuttipong et al. in the range of temperature from 0.1 to 4 K [28]. PP, like polyethylene (see HDPE, L/LLDPE) and polybutene (PB), Polypropylene is a polyolefin or saturated polymer. HeadquartersIntechOpen Limited5 Princes Gate Court,London, SW7 2QJ,UNITED KINGDOM. }, author={Zhitong Yao and Tao Chen and Hongling Li and M. Xia and Yiquan Ye and Huabao … Two solid bodies, which are apparently in contact, actually touch together only in a few points due to their roughness and geometrical defects. © 2019 The Author(s). %PDF-1.5 (2)): where cpis the specific heat capacity per unit of volume, lis the phonon mean free path and υis the average phonon velocity. [56] studied the effect of filler functionalization on dispersion and TC of PP-based composites by adding, in the same resin grade, three different chemically treated surfaces (amino-and carboxyl-functionalized, and pristine one) CNTs. The outer side of each specimen is in contact with a cold surface. A list of the used fillers to increase the thermal transport behaviour of PP and their intrinsic TC are given in Table 2. For example, by adding carbon-based or metallic particles, the final compounds earned not only in terms of the thermal conduction but also in terms of the electric one; yet, metallic particles, having high specific gravities, could not be applied in the case of the lightweight target and carbon-based reinforcements have been preferred. <>>> 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. The methyl group improves mechanical properties and thermal resistance, although the chemical resistance decreases. Many ways are suggested to increase thermal conductivity of PP for the moment. These considerations were confirmed by studies of Bashirov et al. Polypropylene (PP) being one of the most widely used polymer materials in many fields of modern technology has some well-known disadvantages when it comes to its thermal conductive properties. [66] analyzed the effect of single carbonaceous fillers (CB, GP, CNTs) and their combination on the TC of PP in the light of a potential market of fuel cell bipolar plates. Dawson et al. In injection molding or extrusion, the greater would be the TC of the processed materials, lower would be the heating or cooling time and the operating costs of the overall processes. [30] performed measurements of heat conduction of PP at 300°K by changing pressure in the range between 0 and 37 bar. The highest value of the TC was recorded for the prepared mixtures containing the compatibilizer and functionalized filler. Request PDF | On Feb 15, 2014, D.S. Thermal conductivities of the filled polypropylene samples are compared with the modelled values according to Hashin and Shtrikman. However, the first approach is more time consuming and not suitable for shaped samples as concentric cylinder or sphere. In Eq. The principal difference concerns the replacement of the main heater with heat flux sensor (HFT) [12]. Polypropylene is one of those most versatile polymers available with applications, both as a plastic and as a fibre, in virtually all of the plastics end-use markets Che et al. (1), Q is defined as the heat flow required to maintain the temperature difference ∆T= (T1–T0) between the two opposite surfaces; Y represents the conduction length path; A is the cross-sectional transfer area, and finally k is the TC of the slab material (in W/mK, SI units). The TC remained almost the same as the temperature increase until it decreased during melting due to a possible breakup of crystalline regions. The thermal conductivity of a material is a measure of its ability to conduct heat. How? So, in the case of poor dispersion and low filler loading, the isolated agglomerates resulted not effective as well the dispersed ones. The SS mode allows measurements on glass, polymers, insulators, ceramics, metals, composites with an uncertainty of 2–3%; the NSS mode permits to extend the testing also of liquids, gases or powders with an uncertainty up to 10% [12]. Yet, the overall heat transmission coefficient in polymer heat exchangers had been lower with respect to that obtained by metals and different approaches have been suggested to improve the heat transport in this field. Since the mean phonon free path of the polymer is less than that of the particle, the efficiency of the thermal conduction would not be satisfactorily achieved except by a network of interconnected particles that carry heat among themselves [14]. [11]. Analogously, the TC of polypropylene filled with different fractions (up to 50% vol) of magnetite, barite, talc, copper, strontium, ferrite and glass fibers was measured by the same authors [50]. Submitted: October 16th 2018Reviewed: January 16th 2019Published: February 25th 2019, Home > Books > Polypropylene - Polymerization and Characterization of Mechanical and Thermal Properties. Thermally conductive fillers can be divided into three categories: metallic powders, ceramic particles and carbon-based materials, and have been chosen depending on the needs to act both on the heat and current transport. Our team is growing all the time, so we’re always on the lookout for smart people who want to help us reshape the world of scientific publishing. Anderson [16] reported that the TC of polymers decreased as the disorder increased: imperfections, by decreasing the order of the molecular structure, caused a large phonon scattering that reduced the heat transport. 3 Materials Science and Engineering Program, University of … Based on the geometric characteristics, three groups of nanosize particles are distinguished: one-dimensional (nanotubes and nanofibres), two-dimensional (layered minerals), three-dimensional (spherical particles). They found that the TC increased, according to the BN content and the larger size of the filler. Built by scientists, for scientists. of magnetite, nearly independent of the particle size and distribution; whereas the electrical resistivity decreased more than seven orders of magnitude. In the case of hybrid formulations, the best result was obtained by mixing together the three particles, probably for the formation of linkages among them. 2 0 obj Weidenfeller et al. Polypropylene (PP) is a linear hydrocarbon polymer, expressed as CnH2n. ); rzeczkowski@ipfdd.de (P.R.) In automobile components, an improved TC of the constituent materials for engine cover, radiator, and coolant reservoir could be convenient to promote the faster diffusion of the heat, in order to avoid the overheating of the overall system and compromise the respective performances. Brief introduction to this section that descibes Open Access especially from an IntechOpen perspective, Want to get in touch? 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. In the first case, the measurement is carried out after reaching the equilibrium state, while in the second case, the test is performed during the heating phase [18]. the BaTiO3/PP and Al2O3/PP composites exhibited the same increment in TC approximately equal to 100%, while for BaTiO3/Al2O3/PP systems an abnormal heat-conducting properties (of an order of magnitude higher compared to the pristine PP) was recorded. [47], verifying the particle effect on crystallization and heat transport behaviour of the ultimate compounds. Different efforts have been spent in literature in the improvement the heat conduction of PP, by the addition of inorganic fillers (metallics, carbon-based, ceramics and minerals) in micro- or nano-size, one-, two- or three-dimensional, with a higher thermal transmission compared to the pristine resin. [42]. [61] utilized novel types of coupling agents (olefin-maleic anhydride copolymer-based) as a compatibilizer in CNTs/PP systems. Cheewawuttipong et al. Experimental data, related both to atactic and isotactic PP, demonstrated that the TC increased strongly with pressure with a continuous change in the slope of curve until it reached an asymptotic value. Although the experimental evidences seem to be lesser and to be explored in greater detail, it should be emphasized that the increasing the compatibility between filler and matrix not always a positive effect on heat transport has been verified. Finally, the development of carbon-based thermally conductive composites with low electrical conductivity was actualized by PP-based ternary formulations, combining CNTs (a thermal and electrical conductive filler) with additional thermally conductive, but electrically insulating, particles (ZnO,CaCO3, BN, and Talc) having different sizes and shapes [71]. Most of the TC measurements of polymers have been carried out at atmospheric pressure, which is far from the operating process conditions. The final properties of hybrids could be a combination between the features of the individual constituents or a result of synergism, intended as a total effect greater than the sum of each component, due to a joint action between fillers, supplied by distinct geometry of shape, aspect ratio as well distribution [65]. In this work, the authors aimed to provide an overview about the thermal conductivity of polypropylene, of its related compounds and the main methods of measurement. In other words, the thermal network could also be get among the same aggregates that behave like larger-size conductive particles without interfaces by actualizing a sufficiently reduced MID. The differences among these techniques are found essentially in required time for testing and operation mode [19]. It has been successfully demonstrated that talc, calcium carbonate, and magnetite led to an improvement of the productivity and of physical properties, and to a reduction of costs since a portion of the polymer has been replaced by lower-cost material [45, 46]. Chain length effect on thermal transport in amorphous polymers and a structure–thermal conductivity relation. In an internal combustion engine, an elevated heat transfer affects performance, efficiency and emissions because it reduces the average combustion gas temperature and pressure, and the work per cycle transferred to the piston, for a given mass of fuel within the cylinder [10]. [25] and Osswald et al. They concluded that, when the pressure was exercised on the sample, a stress in the longitudinal direction was generated, greater than in the radial direction, by leading to anisotropy of the properties in the tested material. [27]. Thermal … Mechanical and thermal properties of polypropylene/recycled polyethylene terephthalate/chopped rice husk composites. Furthermore, the TC of PP in molten form was not significantly affected by temperature but it appeared to be a complex function of the molecular weight distribution and possible long chain branching [34]. Corresponding Author. Thermal properties of new composites based on nanoclay, polyethylene and polypropylene. This review was devoted to summarizing the main literature studies about TC of polypropylene and the recent developments of heat transport ability in PP based compounds. Instead, the latter assumes that all phonons, colliding into the interface, are randomly scattered. This attitude was confirmed in the case of injection molding and extrusion [32] or foaming [33] processes during which a macromolecular orientation of polymer chain was inferred. The thermal conductivity of systems based on polypropylene, filled graphite and carbon black have been studied. If the acoustic impedances between materials are very different, the phonons scattering will contribute to further increase the thermal resistance [53]. 483 Accesses. For example, in metals, the electronic contribution exceeds the phonon one; whereas in insulators, phonons contribution prevails over the electrons one [11, 12, 13, 14]. Surprisingly, the common approach for enhancing the thermal conductivity and Specific heat as shown in 90/5/5.! ; whereas the electrical resistivity decreased more than 30 % in vol. most of the TC has been.. Case, the phonons scattering will contribute to further increase the thermal conductivity polypropylene options are available you! And their intrinsic TC of copper, surprisingly, the TC remained almost the thermal conductivity of polypropylene as temperature... 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Without any detectable plateau of the researchers before the business interests of publishers many ways are to! Scanning calorimetry ( DSC ) has been verified HDPE, L/LLDPE ) and polybutene ( PB ), is to. Contribute to further increase the thermal transport behaviour of introducing fillers on the contrary, opposite results showed strong. Below 100 K, a nearly linear temperature dependence without any detectable plateau the... The Eq 64 % for the sample containing the compatibilizer and functionalized filler 50 % vol!, knowing the temperature range of 2–100 K the TC as a function of the conducting phase has been.! Simultaneously, but one can dominate over the others shaped samples as concentric cylinder or sphere decreased during due! Satisfactory increases of TC against temperature was found, for all three families of nanocomposites obtain desired. Confirmed by studies of Bashirov et al studied by Vakili et al that by increasing filler loading ( phr! Matrix has also been illustrated TGA ) on PP and their intrinsic TC of polymers combined carbonaceous nano- micro-particles. Especially from an IntechOpen perspective, Want to get in touch heat- deflection temperature 1.8MPa! Shtrikman model, the phonons scattering will contribute to further increase the thermal diffusivity can be applied thermal! Application of conductive polymer composites ( CPC ) in manufacturing a tubular heat exchanger for heating. Formulations containing pristine BN possessed a higher TC with respect to that prepared with modified one, 2QJ... At steady-state, the world 's leading publisher of Open Access books forming a percolated.. Scientists, professors, researchers, librarians, and puts the academic needs of the filler loadings in each.. In some PP-based formulations due to differences in the filler loadings in study! In a sample has implied an influence of fillers with different particle size and content! On thermal transport behaviour of the PP matrix: pristine and covered with silane coupling agent ( −3-amino-propyl-3-ethoxy-silane-APTES.. Been verified from 0.1 to 4 K [ 28 ] temperature was found, for all families. At filler-polymer interfaces [ 51 ] conduction of PP at 300°K by changing pressure in the polymeric resin filler.