Terrence E. Hogan

On the filler flocculation in silica and carbon black filled rubbers: Part II. Filler flocculation and polymer-filler interaction

Abstract Filler flocculation and polymer-filler interaction in silica and carbon black filled rubbers containing different functional end-groups were investigated. Lithium-hexamethyleneimine initiated polymers terminated with a proton (HMI-P-H), SnCl4 (HMI-P-Sn), and a mixture of SnCl4 and tetraethyl orthosilicate (HMI-P-TEOS) were employed to determine the affinities of various functionalities toward fillers. Reduced filler flocculation was found for compounds of HMI-P-Sn and HMI-P-TEOS after thermal annealing at 171 °C for 15 minutes when compared to the annealed HMI-P-H stock. Curing at the same condition used for annealing gave further suppression of filler flocculation for HMI-P-TEOS stock by increased polymer-filler interaction during cure. Polymer-filler interaction was followed by examining G′ strain dependence and the differences in G′ obtained between HMI-P-Sn or HMI-P-TEOS and HMI-P-H (δG′). This treatment gave a peak maximum in the δG′ plot as a function of strain. The magnitude of the maximum...

Lithiated Thiaacetals as Initiators for Living Anionic Polymerization of Diene Elastomers: Polymerization and Compounding

Abstract Polybutadiene and poly(butadiene-co-styrene) elastomers were prepared in high conversions using 2-lithio-2- methyl-1,3-dithiane as the initiator. Polymers were readily prepared with a polydispersity index (PDI) of 1.05 to 1.26 and a Mn of up to 208 kg/mol. The replacement of the 2-methyl substituent with phenyl, trimethylsilyl or 4-dimethylamino phenyl also gave active initiators that incorporated at the head of the chain. However, initiation rates appeared to vary somewhat with the structure of the initiators. The polymerizations obtained are in all cases controlled and apparently living with the live chain ends capable of further reactions. The initiators could be generated prior to addition to the polymerization mixture or by an in-situ procedure. Model studies gave evidence that the dithiane chain end can be opened under cure conditions and react with unsaturation present in the polymer chain. Several of the product polymers were found to impart improved hysteresis to carbon and silica-filled...