Carboxylated Diene Rubber Compositions With Stable Mooney Viscosity
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Solution Overview
Problem
Diene rubbers functionalized with carboxylic acid groups exhibit unstable Mooney viscosity during storage, making it difficult to reliably specify their molecular weight, which is a critical quality control issue in the industry.
Innovation Solution
Adding an organic acid to diene rubbers with functional units containing carboxylic acid groups stabilizes the Mooney viscosity and can reduce solution viscosity, facilitating the processing of these polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diene rubbers are functionalized with carboxylic acid groups to improve interactions with fillers, then the compound quality is improved, but the Mooney viscosity becomes unstable during storage
Solution Approach 1:
An organic acid is introduced as an intermediary substance that interacts with the carboxylic acid groups on the polymer chains. This intermediary forms a stabilizing complex that prevents unwanted interactions between functional groups, thereby maintaining Mooney viscosity stability while preserving the beneficial filler interaction properties of the carboxylic acid groups.
Solution Approach 2:
The chemical environment of the carboxylic acid groups is modified by adding organic acid, which changes the protonation state and intermolecular interactions. This parameter change stabilizes the polymer chain conformation and prevents viscosity drift during storage, while maintaining the functional groups' ability to interact with fillers.
2Reliability
If diene rubbers are functionalized with carboxylic acid groups, then filler interaction is improved, but solution viscosity increases making workup difficult
Solution Approach 1:
The organic acid acts as a mediator that reduces intermolecular associations between functionalized polymer chains in solution. This decreases solution viscosity and improves processability during workup, while the carboxylic acid groups remain available for filler interaction in the final product.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The addition of organic acids to diene rubbers with carboxylic acid groups stabilizes the Mooney viscosity, ensuring consistent polymer properties and facilitating the workup of polymers by reducing solution viscosity, thereby addressing the instability issues and improving quality control.
Implementation Method 1
adding an organic acid to diene rubbers having functional units comprising at least one carboxylic acid groups can stabilize the Mooney viscosity of such rubbers
Implementation Method 2
Adding the organic acid to polymer solutions may also facilitate the work up of the polymers because also solution viscosity of the polymer solutions can be reduced
Data Source
AI summary
A polymer composition comprising(i) at least one first polymer wherein the first polymer is a functionalized diene polymer comprising at least one functional unit having at least one carboxylic acid group or a salt thereof, wherein the functional unit is selected from terminal groups, side groups and combinations thereof, and preferably is a terminal group;(ii) at least one organic acid according to the general formula (1):Ry-(Acg)n (1),(iii), optionally, at least one second polymer,wherein the polymer composition has a total amount of first and second polymer of at least 90% by weight, or at least 95% by weight, based on the total weight of the composition which is 100% and wherein the amount of the at least one first polymer is at least 10% by weight, and wherein the first or the second polymer or both contain from 0 to 100 parts of extender oil per 100 parts of polymer and wherein the amount of polymer indicated by weight percent includes the amount of extender oil when present, and wherein in formula (1)Acg represents an acid group selected from —COOH, —SO3H, —OSO3H, —PO3H2, —OPO3H2 and salts thereof and combinations thereof;n represents an integer from 1 to 10.000;Ry represents an aromatic or aliphatic, linear, cyclic or branched hydrocarbon or heterohydrocarbon residue having a valency corresponding to n, wherein the heterohydrocarbon residue is a hydrocarbon residue that comprises additionally one or more heteroatoms selected from N, S, Si, O, F, Cl, Br and combinations thereof, and, in case Acg is COOH, Ry can also represent H,and wherein the first functionalized diene polymer is a homopolymer of a conjugated diene or a copolymer of at least one conjugated diene and wherein the at least one conjugated diene comprises butadiene, isoprene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 1-phenyl-1,3-butadiene, 1,3-hexadiene, myrcene, ocimenes and farnesene, preferably butadiene and isoprene, more preferably butadiene.Also provided are methods of making such compositions and articles made with such compositions.