Low Density PLA Foam Stability via CO2 HFO Blowing Agent
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Solution Overview
Problem
Low density foams produced using carbon dioxide as a blowing agent often suffer from post-production collapse due to the fast diffusion of the blowing agent, leading to unacceptable dimensional instability.
Innovation Solution
A method involving a blowing agent composition comprising carbon dioxide combined with specific co-blowing agents such as 3,3,3-trifluoropropene, 2,3,3-tetrafluoropropene, and trans-1,3,3-tetrafluoropropene, which minimizes the collapse issue without requiring additives or modifications to the polymer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If carbon dioxide is used as a blowing agent for producing low density foams, then environmental acceptability is improved, but dimensional stability deteriorates due to fast diffusion and post-production collapse
Solution Approach 1:
The patent changes the physical-chemical parameters of the blowing agent system by combining CO2 with HFO co-blowing agents. This combination creates a synergistic effect where the HFO components slow down the diffusion rate of CO2 from the foam cells, thereby maintaining dimensional stability while preserving the environmental benefits of CO2 as the primary blowing agent.
Solution Approach 2:
The invention uses a composite blowing agent system consisting of multiple components (CO2 and HFO co-blowing agents) rather than a single blowing agent. This composite approach allows the system to simultaneously achieve low environmental impact from CO2 and improved dimensional stability from the HFO components, resolving the contradiction between environmental acceptability and foam stability.
2Quantity of substance
If carbon dioxide is used as a blowing agent for low density foams, then foam density is reduced, but mechanical strength deteriorates leading to foam collapse
Solution Approach 1:
The patent modifies the blowing agent composition parameters by introducing HFO co-blowing agents alongside CO2. This parameter change affects the foam cell structure development, creating a more robust cell wall structure that can maintain low overall foam density while providing sufficient mechanical strength to prevent collapse during and after the foaming process.
3Quantity of substance
If carbon dioxide diffuses quickly out of the foam, then low density is achieved, but dimensional stability deteriorates due to structure failure
Solution Approach 1:
The HFO co-blowing agents act as intermediaries that moderate the diffusion process of CO2 from the foam cells. Rather than allowing rapid direct diffusion of CO2 out of the foam structure, the HFO components create a controlled release mechanism that maintains internal pressure longer, preserving the foam's dimensional stability while still achieving low density.
Solution Approach 2:
The patent applies beforehand cushioning by using HFO co-blowing agents that remain in the foam cells longer than CO2, providing a cushioning effect that prevents premature collapse of the foam structure. This prior cushioning allows the foam to maintain its low density while avoiding the dimensional instability that would result from rapid CO2 loss alone.
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 low density foams with improved dimensional stability, maintaining volume and density with minimal change over time, eliminating the collapse problem and achieving high stability without additional polymer modifications.
Implementation Method 1
the fast diffusion of the carbon dioxide or other blowing agent out of the foamed product
Implementation Method 2
Carbon dioxide (CO2) is used as a common blowing agent for production of foamed thermoplastics or polymeric foams
Data Source
Figure 1
AI summary
The invention provides a blowing agent composition and method of making the same comprising mixing carbon dioxide and a co-blowing agent or a blowing agent selected from the group consisting of hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers, hydrofluoroolefins, hydrochlorofluoroolefins, hydrobromofluoroolefins, hydrofluoroketones, hydrochloroolefins, fluoroiodocarbons, alkyl esters, water, and mixtures thereof. Also provided is a method of making a low density foam using the blowing agent composition, and a biodegradable or biorenewable foam formed from a foamable biodegradable or biorenewable resin composition and the blowing agent composition.