Do Nucleators or Processing Methods Affect the Thermal Transport in RacoPP?

Polypropylene (PP) and its copolymers are widely used plastics due to their low density, good mechanical properties, thermal stability, and cost effectiveness.¹ The properties of PP or propylene-ethylene random copolymer (racoPP) can be further enhanced by adding substituted 1,3,5-benzenetrisamides (BTAs), which are an excellent and versatile family of nucleating agents. Their influence on the melt temperature and enhancement of optical and mechanical properties are intensively studied and desired effects.^2-4<br/>In contrast, the thermal conductivity is commonly desired independent of factors such as processing conditions or nucleation rate. However, the polymer crystal structure is affected by processing and the addition of nucleating agents, rendering variations in thermal conductivity likely.⁵ The utilization of PP copolymers in electronic housings, automotive components, or food packaging necessitates an understanding of the thermal transport properties. Therefore, we investigate how the presence of an efficient BTA nucleator (<i>N,N’,N’’-tris(iso-pentyl)benzene-1,3,5-tricarboxamide</i>) affects the thermal diffusivity of injection-molded and hot-pressed racoPP using Lock-In Thermography and Light Flash Analysis. It is compared with a structurally similar BTA additive that has a lower nucleation efficiency (<i>N,N’,N’’-tris(n-butyl)benzene-1,3,5-tricarboxamide</i>), and with no additive at all. By supplementing this data with XRD, SAXS and IR spectroscopy results, we link our thermal characterizations to the polymer crystallinity and structural anisotropy. Ultimately, we assess whether BTA nucleators or processing methods affect the thermal transport in racoPP.<br/><br/>1. H. A. Maddah, <i>American Journal of Polymer Science</i>, 2016, <b>6</b>, 1-11.<br/>2. P. M. Kristiansen, A. Gress, P. Smith, D. Hanft and H.-W. Schmidt, <i>Polymer</i>, 2006, <b>47</b>, 249-253.<br/>3. J. Wang, Q. Dou, X. Chen and D. Li, <i>J. Polym. Sci., Part B: Polym. Phys.</i>, 2008, <b>46</b>, 1067-1078.<br/>4. M. Blomenhofer, S. Ganzleben, D. Hanft, H.-W. Schmidt, M. Kristiansen, P. Smith, K. Stoll, D. Mäder and K. Hoffmann,<i> Macromolecules</i>, 2005, <b>38</b>, 3688-3695.<br/>5. D. Libster, A. Aserin and N. Garti, <i>Polym. Adv. Technol.</i>, 2007, <b>18</b>, 685-695.