Crosslinked Polyolefin Composition Retaining ESCR During Reprocessing
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Solution Overview
Problem
Polyolefin materials face limitations such as susceptibility to deformation and degradation from chemical agents, low barrier properties to gases and VOCs, and insufficient durability, which restrict their use in applications like packaging and pipes, due to limitations in environmental stress cracking resistance and mechanical properties.
Innovation Solution
A crosslinked polymeric composition with a matrix polymer and polar polymer particles selectively crosslinked with a crosslinking agent, which maintains environmental stress cracking resistance and improves mechanical properties during reprocessing, achieving a Normalized Property Balance Index greater than 1.0.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin materials are used to manufacture articles, then high processability and low production cost are achieved, but susceptibility to environmental stress cracking and chemical degradation occurs
Solution Approach 1:
The patent uses a composite material system consisting of a polyolefin matrix polymer combined with a polar polymer (such as polyvinylidene fluoride) that is crosslinked to form a three-dimensional network structure. This composite structure combines the processability advantages of polyolefin with the enhanced mechanical and chemical resistance provided by the crosslinked polar polymer network, thereby resolving the contradiction between ease of manufacture and environmental stress cracking resistance.
Solution Approach 2:
The patent modifies the molecular structure and physical properties of the polyolefin by introducing crosslinking agents that form three-dimensional networks. This parameter change in the polymer structure (from linear chains to crosslinked networks) fundamentally alters the material's mechanical properties and chemical resistance while maintaining processability, thus resolving the contradiction between manufacturability and reliability.
2Strength
If molecular weight of polyolefin is increased to improve mechanical properties, then strength increases, but viscosity increases which limits processability
Solution Approach 1:
Instead of increasing molecular weight, the patent changes the structural parameter by introducing crosslinking. This creates a three-dimensional network that enhances mechanical strength without increasing viscosity, as the crosslinked structure provides reinforcement through topological constraints rather than through increased chain length. This resolves the contradiction by decoupling strength enhancement from viscosity increase.
Solution Approach 2:
The patent creates a composite system where the crosslinked polar polymer network acts as a reinforcement phase within the polyolefin matrix. This composite structure provides enhanced mechanical properties through the crosslinked network's high strength-to-weight ratio, independent of the matrix polymer's molecular weight, thus resolving the contradiction between strength and processability.
3Reliability
If alpha-olefin comonomers are incorporated to improve environmental stress cracking resistance, then ESCR increases, but stiffness decreases
Solution Approach 1:
The patent changes the approach from compositional modification (adding alpha-olefin comonomers) to structural modification (crosslinking). By forming a three-dimensional crosslinked network through crosslinking agents, the material achieves enhanced ESCR through the network's ability to distribute stress, while maintaining stiffness through the rigid crosslinked structure. This resolves the contradiction by achieving ESCR enhancement without the trade-off of reduced stiffness associated with comonomer incorporation.
Solution Approach 2:
The patent introduces a crosslinking agent as an intermediary substance that mediates between the polyolefin matrix and the polar polymer. This intermediary forms crosslinks that simultaneously enhance ESCR and maintain stiffness, avoiding the need to choose between these properties through comonomer selection. The crosslinking agent acts as a mediator that creates a synergistic effect rather than a trade-off.
4Ease of manufacture
If polyolefin materials are used to replace steel and glass, then cost and flexibility are improved, but chemical resistance and durability are insufficient
Solution Approach 1:
The patent creates a composite material system that combines the cost and flexibility advantages of polyolefin with the chemical resistance and durability of crosslinked polar polymer networks. The crosslinked network structure provides a barrier to chemical penetration and enhances durability, allowing polyolefin to replace steel and glass in applications requiring chemical resistance, thus resolving the contradiction between cost/flexibility and reliability.
Solution Approach 2:
The patent fundamentally changes the structural parameters of polyolefin through crosslinking, transforming it from a material with insufficient chemical resistance to one with enhanced durability. This parameter change in the polymer architecture (from linear to crosslinked) provides the chemical resistance needed to replace steel and glass while maintaining the cost and flexibility advantages of polyolefin.
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 crosslinked polymer composition retains high environmental stress cracking resistance and balanced mechanical properties during reprocessing, enhancing its suitability for applications requiring low permeability and chemical resistance, such as packaging and pipes.
Implementation Method 1
a crosslinked polymeric composition comprising a matrix polymer and polar polymer particles selectively crosslinked with a crosslinking agent
Data Source
AI summary
A method may include reprocessing a polymer composition comprising a crosslinked polymeric composition, wherein the crosslinked polymeric composition comprises a matrix polymer having a polar polymer internal phase that is selectively crosslinked with a crosslinking agent, wherein the reprocessed polymer composition retains an environmental stress cracking resistance within 60% of the value for the initial polymer composition when measured according to ASTM D-1693 procedure B and wherein the reprocessed polymer composition presents a Normalized Property Balance Index (NPBI) greater than about 1.0.