PEDM Elastomer Composition for Green Tack and Strength Balance
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Solution Overview
Problem
Existing elastomeric polymer compositions, such as EP(D)M rubbers, lack adequate tack and green strength, which limits their use in manufacturing belts and hoses, and the balance between these properties is challenging to achieve without compromising other essential properties like tensile strength and abrasion resistance.
Innovation Solution
Compositions comprising propylene-α-olefin-diene (PEDM) terpolymers, optionally with ethylene-based copolymers, are formulated to provide improved green tack, tack aging, and green strength, balancing tack and tensile strength through specific weight percentages and Mooney viscosities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EP(D)M polymer composition is used to provide thermal stability and chemical resistance, then reliability is improved, but green strength and tack are insufficient
Solution Approach 1:
The patent uses a composite material system consisting of EP(D)M polymer combined with specific additives including polyethylene wax, processing oil, and sulfur. This composite approach allows the base polymer to provide thermal stability and chemical resistance while the additives compensate for insufficient green strength and tack, enabling the material to meet both reliability and strength requirements simultaneously.
2Ease of operation
If crystallinity is reduced to improve tack, then green strength and other mechanical properties deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer system by incorporating specific ratios of ethylene, propylene, and diene monomers, along with adding polyethylene wax and processing oil. These parameter changes allow the material to achieve optimal tack without requiring reduced crystallinity, thereby maintaining green strength and other mechanical properties.
3Ease of operation
If polymer composition is modified to improve green tack, then balance with tensile strength and abrasion resistance becomes difficult
Solution Approach 1:
The patent introduces processing oil and polyethylene wax as intermediary substances that mediate between the polymer matrix and the requirements for green tack. These intermediaries facilitate improved tack and processability without requiring fundamental changes to the polymer composition that would compromise tensile strength and abrasion resistance, thus simplifying the overall property balance.
Data Source
AI summary
An elastomeric composition is provided that includes from 1 to 100 parts by weight per hundred parts by weight rubber (phr) of a first propylene-α-olefin-diene (PEDM) terpolymer comprising 70 wt % to 92.5 wt % propylene, 7.5 wt % to 30 wt % a C2 or C4-C12 α-olefin, and 3.5 wt % to 20 wt % diene, said wt % based on the weight of the PEDM terpolymer. The PEDM terpolymer V may have a Mooney viscosity (ML(1+4)) of 25 MU to 100 MU. The composition may further include from 0 to 99 phr of an ethylene-based copolymer comprising 40 wt % to 95 wt % ethylene.