PEF Bottle Strain-Induced Crystallization for Shrinkage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Poly(ethylene 2,5-furandicarboxylate) (PEF) containers exhibit high shrinkage due to limited crystallinity, which affects their barrier and mechanical properties, especially in hot-filled applications, as they reach only 10-15% crystallinity compared to PET's 25%.
Innovation Solution
The method involves stretch blow-molding PEF preforms at temperatures between 105° C. to 145° C. with an equivalent axial strain rate of 0.001 to 10 s−1, inducing strain-induced crystallinity to increase glass transition temperature and reduce shrinkage, and includes a relaxation step to enhance crystalline morphology and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If PEF preform is stretched blow-molded at temperatures above glass transition to achieve forming, then container shape is obtained, but high shrinkage occurs due to low crystallinity (10-15%)
Solution Approach 1:
The patent applies parameter changes by controlling the stretching temperature within a specific range (80-100°C) and applying controlled stress during blow-molding to induce strain-induced crystallization. This changes the crystallinity parameter from 10-15% to higher levels, thereby reducing shrinkage while maintaining the desired container shape.
Solution Approach 2:
The patent utilizes phase transitions by inducing crystallization during the stretching process. The controlled application of stress and temperature promotes phase change from amorphous to crystalline structure, increasing crystallinity and reducing shrinkage behavior while forming the container shape.
2Stability of the object's composition
If quiescent crystallization is applied to PEF, then some crystallinity is achieved, but glass transition temperature does not increase sufficiently and shrinkage remains high
Solution Approach 1:
The patent replaces quiescent crystallization with strain-induced crystallization. Instead of relying on passive crystallization, the invention applies mechanical stress during blow-molding to actively induce crystallization, which results in higher crystallinity and a more significant increase in glass transition temperature.
Solution Approach 2:
The patent applies preliminary action by inducing crystallization during the stretching process itself, before the container is fully formed and cooled. This preliminary crystallization step ensures that the crystalline structure is established early, leading to higher glass transition temperature and reduced shrinkage in the final product.
3Productivity
If stretching is performed at higher strain rates to improve processing speed, then productivity increases, but crystallinity induction is reduced
Solution Approach 1:
The patent applies dynamics by optimizing the stretching process parameters, including strain rate and temperature profile, to simultaneously achieve high productivity and effective crystallization. The controlled dynamic stretching conditions allow crystallization to occur during the forming process itself, eliminating the trade-off between speed and crystallinity.
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
This approach results in containers with improved high-temperature properties and reduced shrinkage, enabling their use in hot filling applications with increased crystallinity and enhanced barrier and mechanical properties.
Implementation Method 1
the stretch blow-molding comprises a stretching step of the preform to a ratio higher than the natural draw ratio of poly(ethylene 2,5-furandicarboxylate) at a temperature in a range of 105° C. to 145° C.
Implementation Method 2
inducing strain-induced crystallinity to increase glass transition temperature and reduce shrinkage
Data Source
AI summary
A container, preferably a bottle, is fabricated in a method comprising: —providing a preform comprising poly(ethylene 2, 5-furandicarboxylate); —stretch blow-molding the preform to form the container, wherein the stretch blow-molding comprises a stretching step of the preform to a ratio higher than the natural draw ratio of poly(ethylene 2, 5-furandicarboxylate) at a temperature in a range of 105° C. to 145° C., preferably in a range of 110° C. to 140° C., and at an equivalent axial strain rate at a reference temperature of 100° C. in the range of 0.001 to 10 s−1, preferably in a range of 0.03 to 3 s−1.