Polyolefin Grafted Polydiene Polymers for Tire Rubber
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Solution Overview
Problem
Rubber compositions used in tire applications, such as NR/BR blends, suffer from hysteresis loss and ozone cracking due to polymer free ends and in-chain unsaturation, which are not adequately addressed by current solutions like anti-ozonants and EPDM, leading to inhomogeneous curing and poor mechanical properties.
Innovation Solution
The grafting of polyolefins onto the backbone of polydiene polymers using sulfur-containing functionalizing agents to create polyolefin grafted polydiene polymers, which are then incorporated into rubber compositions to reduce hysteresis loss and enhance ozone cracking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-ozonants are added to reduce ozone cracking, then ozone cracking resistance is improved, but surface appearance deteriorates due to migration and discoloration
Solution Approach 1:
The patent extracts the harmful in-chain unsaturation from the rubber polymer structure through selective hydrogenation or use of saturated polydiene backbones. This removes the root cause of ozone cracking susceptibility, eliminating the need for anti-ozonant additives that would otherwise migrate and discolor the surface, thus resolving the contradiction between ozone resistance and surface appearance
Solution Approach 2:
The patent creates a composite polymer structure by grafting polyolefin side chains onto a polydiene backbone. The polyolefin portions provide saturation and ozone resistance, while the polydiene backbone maintains elastomeric properties. This composite structure achieves inherent ozone cracking resistance without requiring additional anti-ozonant chemicals that would compromise surface appearance
2Reliability
If EPDM is used to reduce ozone cracking, then ozone cracking resistance is improved, but mechanical properties deteriorate due to inhomogeneous curing
Solution Approach 1:
The patent applies local quality by creating a heterogeneous polymer structure where polyolefin grafts (providing ozone resistance) are distributed along the polydiene backbone (providing elastomeric properties and cure sites). This localized functional distribution allows different regions of the polymer to contribute different properties, achieving both ozone resistance and good mechanical properties through heterogeneous but homogeneous curing
Solution Approach 2:
The grafted polyolefin-polydiene structure functions as a composite material where the polyolefin side chains provide saturation for ozone resistance while the polydiene backbone provides elastomeric properties and cure sites. This composite architecture enables homogeneous curing throughout the polymer structure, avoiding the inhomogeneous curing problems of EPDM while maintaining both ozone resistance and mechanical properties
3Reliability
If polyolefin is grafted onto polydiene backbone, then ozone cracking resistance is improved, but hysteresis loss is reduced
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing polyolefin grafts with different saturation levels and molecular weights. By controlling the degree of grafting and the structure of polyolefin side chains, the patent optimizes both ozone cracking resistance and hysteresis loss properties, demonstrating parameter changes as a key inventive principle
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 polyolefin grafted polydiene polymers significantly reduce hysteresis loss and improve ozone cracking resistance, as demonstrated by lower loss modulus and tan δ values, while maintaining or improving mechanical properties and extending ozone resistance in tire formulations.
Implementation Method 1
at least one sulfur containing functionalizing agent which grafts the polyolefin onto at least one non-terminal position on the polydiene polymer backbone
Data Source
AI summary
Embodiments of the present disclosure are directed to polyolefin grafted polydiene polymers, wherein the polyolefin grafted polydiene polymers comprises a polydiene having a polydiene polymer backbone, a polyolefin, and at least one sulfur containing functionalizing agent which grafts the polyolefin onto at least one non-terminal position on the polydiene polymer backbone.