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Some rheological properties of mineral lubricating oils containing polyolefin (OCP) (ethylene/propylene copolymer) and poly(alkyl methacrylate) (PAMA) mixed additives over a wide composition range have been examined. Increasing the OCP content significantly increases the viscosity and shear stability of solutions, whereas the viscosity index is directly proportional to the PAMA content. The pour point values of the additive solutions investigated are lower than −30°C even for the smallest concentration of PAMA in the polymer mixture of 15 wt.% (at a total polymer mixture concentration in oil of 2 wt.%). The viscosities of dilute mixed additive solutions obey the typical Krigbaum‐Wall equation and, due to the negative viscometric interaction parameter values (Δb12 < 0), the OCP/PAMA mixture is found to be immiscible. The immiscibility becomes more pronounced on increasing the overall polymer concentrations. The viscosities of concentrated mixed additive solutions decrease significantly with an increase of OCP content, showing a minimum of half the initial value at a polymer ratio of about 50/50. On decreasing the polymer concentration to practical levels as well as increasing the temperature, the viscosity values approach the ideal additivity law. Based on the ratio of specific viscosities at 40 and 100°C (Q), the OCP additive solution shows a better thickening effect at lower temperatures (Q < 1). On the other hand, the PAMA additive solution shows a better effect at higher temperatures (Q > 1) with more coherent thickening with temperature change. The mixed polymer additive, containing ∼10 wt.% OCP and ∼90 wt.% PAMA, is a nearly optimal viscosity‐index improver showing the same thickening effect at different temperatures. The results obtained are promising as regards the design of lubricant formulations with mixed polymeric additives.

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.

Low conversion kinetics of terpolymerization of N,N‐dimethylaminoethyl methacrylate (DMAEM) and dodecyl methacrylate (DDMA) with methyl methacrylate (MMA) or styrene (ST) was investigated. Reactions were performed at 70°C, in toluene solutions, using peroxide initiator. The interdependence between terpolymer and monomer feed composition was successfully described by Alfrey‐Goldfinger equation and the unitary, binary, and ternary azeotropes were calculated. In MMA‐containing system, the wide pseudoazeotropic region with existence of true azeotropic point was observed and experimentally confirmed at the DMAEM:MMA:DDMA molar ratio of 56:41:3. In the ST‐containing system compositional heterogeneity was significant, more than 10 mol%. Required copolymerization reactivity ratios were determined by linear and nonlinear methods. The glass transition temperatures of synthesized terpolymers are found to be between those of the corresponding homopolymers and relative to their content. Increase in the MMA or ST contents and decrease in the DDMA content in terpolymers results in an increase in their glass transition temperatures. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Solution terpolymerization processes of methyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate using bifunctional 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane or monofunctional tert-butylperoxy-2-ethylhexanoate initiator were investigated. The first set of terpolymerizations was performed in 2 M xylene solutions, isothermally at 91, 100, 105, and 115 °C. The terpolymerization kineticsconcentrations of molecular species, kinetic chain length, molar mass averages as functions of the reaction timewas modeled by the Villermaux−Blavier tendency kinetic model for radical polymerization. Complete monomer conversions and high molar masses of terpolymers were achieved in a simple batch process with bifunctional initiator. The second set of polymerization reactions was performed in 2 M mineral base oil solutions, under isothermal conditions at 115 and 120 °C, using the bifunctional initiator. By varying the monomer mixture composition and concentrations of the initiator and chain transfer agent, n-dodecyl mercaptan, the terpolymers of different composition and molar mass were obtained. The solution properties of alkyl methacrylate terpolymers as lubricating oil rheology modifierskinematic viscosity, viscosity index, shear stability, and pour pointwere established. A strong correlation between molar mass distribution of synthesized polymers and rheological properties of polymer solutions was revealed by an applied optimization procedure.

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.

N-(2,4,6-Tribromophenyl)maleimide (TBPMI) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in toluene solution using 2,2'-azoisobutyronitrile as free-radical initiation. The copolymerization reactivity ratios were found to be for the system TBPMI/MA r l = 0,095 i. 0,045 (TBPMI) and r2 = 2,17 5 0,142 (MA) and for the system TBPMVMMA rl = 0,037 -+ 0,042 (TBPMI) and r2 = 4,32 f 0,230 (MMA); Q and e values were also calculated. The initial rate of copolymerization, R,, for TBPMI/MA sharply decreases as the content of TBPMI in the monomer mixture increases but the composition of the feed does not have a strong influence on R, for the TBPMI/MMA copolymerization system. The course of copolymerization to high conversion is characterized by an increase of conversion up to a mole fraction of TBPMI of 0,7 in the monomer mixture, when MA was used as the comonomer. An opposite behaviour was found with MMA. Its copolymers show a considerable increase of thermal stability as well as of the glass transition temperatures with increasing TBPMI content.

SynopsisThe terpolymerization of acrylonitrile with styrene and 2,3-dibromopropyl acrylate in emulsion and dimethyl formamide solution was investigated. Polymerizations, when stopped a t low conversions, yielded terpolymers that showed good agreement between experimental and theoretical copolymerization composition data, calculated from the Alfrey-Goldfinger equation. The relationship between monomer feed and terpolymer compositions is displayed on triangular coordinate graphs proposed by Slocombe. By using a computer program the lines of unique composition and binary azeotropic composition for both systems were established. In the case of emulsion polymerization the azeotropic ternary point was determined at a molar ratio for acrylonitrile/styrene/2,3dibromopropyl acrylate of 0.27/0.61/0.12. The experimental results of emulsion terpolymerization fit the calculated curves satisfactorily over a wide range of monomer compositions up to high conversions. The influence of 2,3-dibromopropyl acrylate on the thermal and flammability characteristics of the terpolymers is described.