Halogenated Isoolefin Elastomer Processability with Fillers
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Solution Overview
Problem
Halogenated isoolefin elastomers used in tire innerliners face challenges with slow stress relaxation and poor processability when filled with carbon black or other fillers, leading to difficulties in handling and performance during tire construction.
Innovation Solution
Developing halogenated isoolefin elastomers with specific Mooney viscosity, molecular weight, and branching index characteristics, along with the inclusion of carbon black or clay fillers, to enhance stress relaxation and processability, resulting in improved melt properties and physical properties comparable to conventional bromobutyl rubbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogenated isoolefin elastomers are filled with carbon black or other fillers to enhance physical properties, then air barrier qualities and flex fatigue resistance are improved, but stress relaxation becomes slow and processability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Mooney viscosity (15-26), molecular weight (Mn < 270,000), and branching index (0.4-1.1) of the halogenated isoolefin elastomer. These parameter optimizations enable the elastomer to maintain fast stress relaxation and good processability even when filled with carbon black or clay, while preserving air barrier qualities and flex fatigue resistance.
2Strength
If halogenated isoolefin elastomers are filled with carbon black or other fillers to enhance physical properties, then flex fatigue resistance is improved, but stress relaxation becomes slow and processability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Mooney viscosity (15-26), molecular weight (Mn < 270,000), and branching index (0.4-1.1) of the halogenated isoolefin elastomer. These parameter optimizations enable the elastomer to maintain fast stress relaxation and good processability even when filled with carbon black or clay, while preserving air barrier qualities and flex fatigue resistance.
3Ease of operation
If the molecular weight and branching index of halogenated isoolefin elastomers are optimized to improve stress relaxation, then processability is improved, but filler loading capacity may be affected
Solution Approach 1:
The patent applies parameter changes by optimizing the Mooney viscosity (15-26), molecular weight (Mn < 270,000), and branching index (0.4-1.1) of the halogenated isoolefin elastomer. These parameter optimizations enable the elastomer to maintain fast stress relaxation and good processability while accommodating filler loadings of 20-70 phr carbon black or 1-30 phr clay, achieving a balance between processability and filler loading capacity.
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 solution enables faster stress relaxation and improved processability of the filled elastomer composition, maintaining performance advantages such as air barrier qualities and flex fatigue resistance, while allowing for easier handling and manufacturing of tire innerliners.
Implementation Method 1
When a polymer is deformed, a stress builds up in the polymer due to a decrease in entropy. However, even if the polymer is kept in the strained state, the stress will drop or relax because the polymer chains tend to diffuse back to the isotropic state of highest thermodynamic probability.
Implementation Method 2
Due to the general enhancement in air barrier qualities of various polymer blends when clays are present, there is a desire for a nanocomposite with low air permeability
Data Source
AI summary
The present invention provides an elastomeric composition processable in a curable, filled rubber formulation. The composition comprises a halogenated interpolymer of a C4 to C7 isoolefm and from 3 to 20 weight percent alkylstyrene and comprising from 0.2 to 2 mole percent haloalkylstyrene, a Mooney viscosity less than 27, a number average molecular weight less than 270,000, a weight average molecular weight less than 470,000, a z-average molecular weight less than 700,000, and a branching index (g') from 0.4 to 1.1. Also disclosed are a method of making a cured, filled rubber article, comprising compounding the elastomeric composition with filler and curative, processing the compounded composition to form a shape of the article, and curing the composition to obtain the article in the formed shape, as well as a tire comprising an innerliner made by the method.