Ethylene Vinylacetate Copolymer Mechanical Strength via Stage Temperature Control
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Solution Overview
Problem
Ethylene vinylacetate copolymers have low mechanical strength due to their low crystallinity, which limits their application in high-stress environments such as solar module sealing, where improved mechanical properties are required.
Innovation Solution
A method for preparing ethylene vinylacetate copolymer by controlling polymerization conditions in an autoclave reactor, specifically by setting the upper stage temperature between 130 to 160°C, lower stage temperature between 170 to 230°C, and pressure between 1800 to 2100 bar, to reduce long chain branches and increase number average molecular weight, resulting in improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ethylene vinylacetate copolymer is prepared by conventional polymerization in an autoclave reactor, then the copolymer can be produced with high transparency and adhesion property, but the mechanical strength is low due to low crystallinity and high long chain branch content
Solution Approach 1:
The polymerization process is divided into two distinct stages with different temperature conditions. The first stage uses a lower temperature (130-160°C) to control long chain branch formation, while the second stage uses a higher temperature (170-230°C) to promote crystallinity and mechanical strength. This segmentation of the polymerization process allows independent optimization of different structural properties.
Solution Approach 2:
The polymerization process employs dynamic temperature control, transitioning from isothermal conditions in the first stage to different temperature conditions in the second stage. This dynamic adjustment of temperature parameters enables the copolymer structure to evolve toward higher crystallinity and mechanical strength while controlling branch content.
2Productivity
If the temperature in the autoclave reactor is increased to improve polymerization rate, then productivity increases, but long chain branch content increases which reduces mechanical strength
Solution Approach 1:
The polymerization is divided into two stages: first stage at lower temperature (130-160°C) to control branch formation while maintaining reasonable polymerization rate, and second stage at higher temperature (170-230°C) to enhance crystallinity and mechanical strength. This segmentation allows the system to achieve both productivity and strength.
Solution Approach 2:
The temperature parameter is changed between two distinct ranges during the polymerization process. The first stage uses 130-160°C to balance polymerization rate and branch control, while the second stage uses 170-230°C to maximize mechanical strength through enhanced crystallinity development.
3Strength
If the polymerization temperature is kept low to reduce long chain branches, then mechanical strength improves, but the polymerization rate decreases
Solution Approach 1:
The process is segmented into two stages: first stage at lower temperature (130-160°C) to control long chain branch content and improve mechanical strength, and second stage at higher temperature (170-230°C) to accelerate polymerization and improve crystallinity. This segmentation resolves the trade-off between strength and productivity.
Solution Approach 2:
The first stage performs preliminary polymerization at lower temperature to establish controlled branch content and initiate mechanical strength development. The second stage then builds upon this foundation with higher temperature processing to achieve final mechanical properties and complete polymerization.
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 method produces ethylene vinylacetate copolymer with a low content of long chain branches, exhibiting a linear structure and high number average molecular weight, thereby enhancing tensile strength and mechanical properties, making it suitable for applications requiring robust sealing and mechanical integrity.
Implementation Method 1
polymerizing ethylene monomers and vinylacetate monomers in an autoclave reactor, in the presence of an initiator
Implementation Method 2
the pressure of the autoclave reactor is 1800 to 2100 bar
Implementation Method 3
the temperature of the upper stage of the autoclave reactor in the polymerization step is 130 to 160° C., the temperature of the lower stage of the autoclave reactor in the polymerization step is 170 to 230° C.
Data Source
AI summary
The present invention relates to a method for preparing ethylene vinylacetate copolymer that can improve the mechanical strength of copolymer by controlling the polymerization conditions using an autoclave reactor.