The properties of styrene/dodecyl methacrylate/octadecyl methacrylate terpolymers as viscosity index improvers of lubricating mineral oils were investigated. Terpolymers of different composition and molar mass were prepared by peroxide-initiated polymerization of the monomer mixture in a mineral base oil solution. All the terpolymer solutions in base oil exhibited high kinematic viscosity and viscosity index values (> 130), proving their high thickening efficiency. The ratio of viscosity values at 100°C and 40°C of styrene/alkyl methacrylate additive solutions was between 0.95 and 1.0, showing the coherent thickening effect in a wide temperature range, comparable with pure alkyl methacrylate additives. Increasing content of styrene in the additive and decreasing molar mass of the terpolymer resulted in a decrease in viscosity and viscosity index while the shear stability increased. The obtained results give guidelines for optimization of the terpolymers composition and structure in order to assure the best lubricant application properties.

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Poly(D,L‐lactide) and poly(D,L‐lactide‐co‐glycolide) with various composition and with one methacrylate and one carboxylate end group were synthesized and grafted onto poly(vinyl alcohol) (PVA) via the carboxylate group. The graft copolymers were crosslinked via the methacrylate groups using a free radical initiator. The polymer networks were characterized by means of NMR and studied qualitatively by means of IR spectroscopy. The influence of the glycolide content in the polyester grafts and of the number of ester units in the grafts on thermal properties and swellability were studied as well. The high swellability in water is characteristic of all hydrogels. Differential scanning calorimetry (DSC) showed a single glass transition temperature that occurs in the range between 51 and 69 °C. Thermogravimetric analysis (TGA) of the networks showed the main loss in weight in the temperature range between 290 and 370 °C. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4536–4544, 2007

This study describes low-conversion terpolymerization kinetic investigations of methyl methacrylate/dodecyl methacrylate/octadecyl methacrylate (MMA/DDMA/ODMA) and styrene/dodecyl methacrylate/octadecyl methacrylate (ST/DDMA/ODMA) systems. Terpolymerizations were performed isothermally (70-105• C), in 1 mol dm −3 xylene solutions, using 0.01 mol dm −3 of bifunctional peroxide initiator 1,1-di(tertbutylperoxy)-3,3,5-trimethylcyclohexane or monofunctional tert-butylperoxy-2-ethylhexanoate. Synthesized terpolymers were characterized with respect to composition and molar mass distribution. Initial polymerization reaction rates as well as terpolymer average molar masses decreased with increasing MMA or ST content in the monomer mixture, for both initiators and all investigated temperatures. Overall reaction rates were found to be significantly larger for the MMA/DDMA/ODMA system. In the MMA/DDMA/ODMA system, experimental terpolymer compositions were found to be similar to the initial monomer feed compositions -all the experimental monomer feed mixtures were close to the azeotropic composition. The Alfrey-Goldfinger terpolymerization equation was successfully used for the description of MMA/DDMA/ODMA terpolymerization kinetics, where the existence of the true azeotropic ternary point was established. The same equation did not perform as well for the ST/DDMA/ODMA terpolymerization system.

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