Modified EVOH Geomembrane Peel Strength
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Solution Overview
Problem
Geomembranes experience delamination and leakage due to peeling between the EVOH layer and the adhesive layer when exposed to high temperature and high humidity, leading to the leakage of harmful substances.
Innovation Solution
A multilayer geomembrane structure comprising a barrier layer made of modified ethylene-vinyl alcohol copolymer (EVOH) with an ethylene unit content of 18-55 mol% and a primary hydroxyl group, laminated with an adhesive layer and a thermoplastic resin layer, enhancing peel strength and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional EVOH layer is used in the geomembrane, then the barrier properties to odor and flavor are excellent, but the peel strength between the barrier layer and adhesive layer deteriorates after prolonged exposure to high temperature and high humidity
Solution Approach 1:
The invention modifies the EVOH polymer at specific local positions by introducing graft chains containing hydroxyl groups at regular intervals along the polymer backbone. This local modification approach maintains the overall EVOH barrier properties while creating specific adhesive interaction sites that prevent delamination under high temperature and humidity conditions.
Solution Approach 2:
The invention creates a composite structure within the EVOH barrier layer by combining modified EVOH chains with graft chains containing hydroxyl groups. This composite polymer structure integrates the barrier properties of EVOH with the adhesive properties of hydroxyl-containing groups, resolving the contradiction between barrier performance and adhesive strength.
2Adaptability or versatility
If the geomembrane is placed under high temperature and high humidity conditions, then the operational environment is realistic for landfill applications, but delamination occurs and harmful substances leak out
Solution Approach 1:
The invention performs preliminary chemical modification of the EVOH polymer during manufacturing, introducing hydroxyl-containing graft chains before the geomembrane is installed. This preliminary action ensures that the adhesive bonds are already formed and stabilized before the geomembrane is exposed to high temperature and humidity conditions, preventing delamination from occurring in the first place.
Solution Approach 2:
The hydroxyl-containing graft chains act as a cushioning mechanism that anticipates and prevents the delamination problem. These modified groups create strong adhesive bonds in advance, cushioning against the detrimental effects of high temperature and humidity that would otherwise cause peeling and leakage.
3Strength
If the peel strength is improved by modifying the EVOH layer, then the bond between barrier layer and adhesive layer is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The invention changes the chemical parameters of the EVOH polymer by controlling the degree of grafting and the type of hydroxyl-containing groups introduced. By adjusting these parameters within specific ranges, the patent achieves optimal peel strength while maintaining manufacturability, as the modification can be performed using standard polymerization techniques with controlled reaction conditions.
Data Source
AI summary
There is provided a geomembrane consisting of a multilayer structure comprising a barrier layer (A), an adhesive layer (B) made of an acid-modified thermoplastic resin and a thermoplastic resin layer (C), wherein the thermoplastic resin layer (C) is laminated on at least one side of the barrier layer (A) via the adhesive layer (B), and the barrier layer (A) has an ethylene unit content of 18 mol% or more and 55 mol% or less and comprises a modified ethylene-vinyl alcohol copolymer comprising a modifying group having a primary hydroxyl group. The geomembrane exhibits excellent peer strength between the barrier layer and the adhesive layer, exhibits further improved peel strength after prolonged exposure to high temperature and high humidity conditions.