Hydrogenated Styrenic Block Copolymer Melt Flow
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Solution Overview
Problem
Conventional styrenic block copolymers face challenges in achieving a balance between low viscosity for improved processability and maintaining desirable elastic and mechanical properties, often resulting in inferior properties when additives are used to reduce viscosity.
Innovation Solution
A selectively hydrogenated styrenic block copolymer with specific molecular weight ranges and structural configurations, including S-E-S and (S-E1)nX structures, is developed, which incorporates a coupling agent to enhance processability and mechanical properties while minimizing the use of additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If substantial amounts of polyolefins, extending oils, tackifying resins and waxes are added to conventional styrenic block copolymers, then viscosity is reduced and processability is improved, but elastic properties deteriorate and processing problems such as smoking and die build-up occur
Solution Approach 1:
The patent applies parameter changes by selectively hydrogenating the polydiene blocks to reduce viscosity while maintaining elastic properties. The hydrogenation degree is controlled at 50-90%, which modifies the molecular structure to achieve lower viscosity without compromising the elastic recovery characteristics of the block copolymer
Solution Approach 2:
The patent creates a composite material system by combining polystyrene blocks with partially hydrogenated polydiene blocks in a block copolymer structure. This composite architecture allows the material to exhibit both the processability benefits of reduced viscosity and the elastic properties of the hydrogenated diene segments
2Ease of operation
If conventional styrenic block copolymers are formulated to have low viscosity and improved processability, then processability is improved, but mechanical properties and aid in preparation of molded and extruded articles are not achieved
Solution Approach 1:
The patent modifies the molecular weight parameters of the polydiene blocks (15,000-50,000 g/mol) and controls the hydrogenation degree (50-90%) to achieve a balance between low viscosity for processability and sufficient mechanical properties for reliable molded and extruded articles
3Strength
If conventional styrenic block copolymers maintain high viscosity to preserve mechanical properties, then mechanical properties are maintained, but processability deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the polydiene blocks through selective hydrogenation, which reduces chain entanglement and viscosity while preserving the block copolymer architecture that provides mechanical properties. The hydrogenation level is optimized to achieve both low viscosity and maintained mechanical performance
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 achieves low viscosity and high melt flow rates, allowing for easier processing without compromising elastic properties, such as elongation at break and tensile strength, and reduces the need for processing aids that can cause issues like smoking and die build-up.
Implementation Method 1
at least 80 percent of conjugated diene double bonds in the block copolymer are reduced
Data Source
AI summary
The disclosure relates to a hydrogenated styrenic block copolymer with high vinyl content, low viscosity, low order-disorder temperature and improved processability. The hydrogenated styrenic block copolymers can be extruded or molded with a minimum of additives. The hydrogenated styrenic block copolymers have high melt flows allowing for ease in processing such as injection molding, overmolding, dipping, extrusion, roto-molding, slush molding, fiber spinning, film making, 3D printing and foaming.