Effect of Thermal History and Shear on the Viscoelastic Response of iPP Containing an Oxalamide-Based Organic Compound

Abstract

We report on the role of temperature and shear on the melt behavior of iPP in the presence of the organic compound N1,N1′-(propane-1,3-diyl)bis(N2-hexyloxalamide) (OXA3,6). It is demonstrated that OXA3,6 facilitates a viscosity suppression when it resides in the molten state. The viscosity suppression is attributed to the interaction of iPP chains/subchains with molten OXA3,6 nanoclusters. The exact molecular mechanism has not been identified; nevertheless, a tentative explanation is proposed. The observed viscosity suppression appears similar to that encountered in polymer melts filled with solid nanoparticles, with the difference that the OXA3,6 compound reported in this study facilitates the viscosity suppression in the molten state. Upon cooling, as crystal growth of OXA3,6 progresses, the decrease in viscosity is suppressed. Retrospectively, segmental absorption of iPP chains on the surface of micrometer-sized OXA3,6 crystallites favors the formation of dangling arms, yielding OXA3,6 crystallites decorated with partially absorbed iPP chains. In other words, the resulting OXA3,6 particle morphology resembles that of a hairy particle or a starlike polymer chain. Such hairy particles effectively facilitate a viscosity enhancement, similar to branched polymer chains. This hypothesis and its implications for the shear behavior of iPP are discussed and supported using plate–plate rheometry and slit-flow experiments combined with small-angle X-ray scattering analysis.

Nonequilibrium Melt State of Ultra-High-Molecular-Weight Polyethylene: A Theoretical Approach on the Equilibrium Process

“…Regarding the model outcomes for polydisperse chains, they have been obtained using log-normal distributions. Such distribution functions are typically used to capture the actual MWD of PE and isotactic polypropylene (iPP) polymer melts. − …”

Gelation and Crystallization Phenomena in Polyethylene Plastomers Modified with Waxes

“…When studying nucleation effects in polypropylene (PP) homopolymers and random copolymers by soluble nucleating agents [ 3 ] via this technique, the fibril and network formation before the actual PP crystallization can be observed under quasi-quiescent conditions, i.e., within the limits of linear viscoelastic response [ 22 , 23 , 24 , 25 ]. In this way, the excellent transparency effect of sorbitol and trisamide types [ 22 , 23 , 25 ], as well as the similar function of novel oxalamide types [ 24 ], could be explained. In addition, the two saturation levels normally observed for this class of nucleating agents [ 23 , 26 ] become logical: The first plateau at lower concentration corresponds to a concentration sufficient for fibril formation, whereas the second plateau indicates a network structure.…”

“…When studying nucleation effects in polypropylene (PP) homopolymers and random copolymers by soluble nucleating agents [3] via this technique, the fibril and network formation before the actual PP crystallization can be observed under quasi-quiescent conditions, i.e., within the limits of linear viscoelastic response [22][23][24][25]. In this way, the excellent transparency effect of sorbitol and trisamide types [22,23,25], as well as the similar function of novel oxalamide types [24], could be explained.…”

Data Mining of Polymer Phase Transitions upon Temperature Changes by Small and Wide-Angle X-ray Scattering Combined with Raman Spectroscopy

“…The emphasis on combined techniques has been proven to be very beneficial for the elucidation of polymer nanostructure formation (mainly crystallization) under processing-relevant conditions that mimic industrial environments, such as fast quenching [ 8 , 9 ], solid-state films drawability [ 10 ], 2D stretching [ 10 ], thin film formation by spin coating [ 11 , 12 , 13 ] or polymerization under sc-CO 2 [ 14 , 15 , 16 , 17 ] and, recently, 3D printing [ 18 , 19 ] and laser sintering [ 20 ]. Substantial efforts have been dedicated to the understanding of the interplay of the different flow fields [ 21 , 22 , 23 , 24 , 25 , 26 ] and thermal treatments [ 1 ] that replicate the industrial conditions at which polymers are subjected in processing, such as extrusion, injection moulding [ 27 ], blow moulding [ 28 , 29 ], fibre spinning, drop-casting, filament deposition modelling and inkjet printing on crystallization.…”