Vulcanization Accelerators and Silica Coupling Agents in Polyisoprene Melts.

IF 2.8 2区 化学 Q3 CHEMISTRY, PHYSICAL
Nikolaos Patsalidis, George J Papakonstantopoulos, Jan Domurath, Patrycja Polińska, Craig Burkhart, Vagelis Harmandaris, Manolis Doxastakis
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引用次数: 0

Abstract

The achievement of sufficient dispersion of vulcanization accelerators is critical to tailoring superior cross-linked elastomers. Modern recipes rely on multicomponent formulations with silica particles covered by coupling agents. We study the molecular properties of select accelerators in polyisoprene melts and their affinity for functionalized surfaces via extensive all-atom molecular dynamics simulations. We focus on the common (N-cyclohexyl)-2-benzothiazole sulfenamide (CBS), 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane (DBTH), and diphenyl guanidine (DPG) molecules and their mixing characteristics at curing temperatures. Our results support a low self-association affinity for CBS and DBTH within polyisoprene, whereas DPG forms small hydrogen-bonded aggregates. Subsequently, we examine systems in contact with silica interfaces, bare or grafted with (3-mercaptopropyl)triethoxysilane (MPTES), (3-octanoylthio) 1-propyl-triethoxysilane (NXT), and bis[3-(triethoxysilyl)propyl]disulfide (TESPD). Accelerator-substrate affinity is first assessed at infinite dilution using free energy calculations and subsequently at finite concentrations. Accelerators exhibit high substrate affinity (DPG > CBS > DBTH) irrespective of functionalization. However, coupling agents are able to displace from the surface a significant amount that increases with the grafting density and the size of the coupling agent. Finally, we investigate the behavior of DPG in binary DPG-CBS formulations, where the former can act as a covering agent that solubilizes CBS into the bulk polymer.

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来源期刊
CiteScore
5.80
自引率
9.10%
发文量
965
审稿时长
1.6 months
期刊介绍: An essential criterion for acceptance of research articles in the journal is that they provide new physical insight. Please refer to the New Physical Insights virtual issue on what constitutes new physical insight. Manuscripts that are essentially reporting data or applications of data are, in general, not suitable for publication in JPC B.
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