Activated Carbon Cell Size Control in Extruded Polystyrene Foam
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Solution Overview
Problem
Existing extruded polymer foam technologies face challenges in achieving larger cell sizes using non-HCFC blowing agents while maintaining the physical properties of conventional extruded polystyrene foams and minimizing corrosion in equipment.
Innovation Solution
A method involving heating alkenyl aromatic polymer materials with a porous carbon-containing compound like activated carbon, injecting a blowing agent, cooling the mixture, and introducing a liquid that evaporates or reacts to form a gas, which is absorbed by the porous carbon compound, to produce a rigid, closed-cell foam with controlled cell size and reduced corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If non-HCFC blowing agents (HFCs and CO2) are used to replace CFCs and HCFCs, then environmental sustainability is improved (lower ODP and GWP), but cell size becomes too small resulting in higher density and reduced insulative value
Solution Approach 1:
A water-soluble polymer is introduced as an intermediary substance that mediates between the non-HCFC blowing agent and the polymer melt. The polymer modifies the blowing agent's behavior, enabling larger cell sizes to form while using environmentally friendly blowing agents like HFCs and CO2, thus resolving the contradiction between environmental sustainability and cell size
Solution Approach 2:
The invention changes the physical and chemical parameters of the blowing agent system by adding a water-soluble polymer. This modification alters the solubility, expansion characteristics, and cell formation dynamics of the blowing agent, allowing non-HCFC agents to produce adequate cell sizes without compromising environmental benefits
2Object-affected harmful factors
If non-HCFC blowing agents are used, then environmental sustainability is improved, but the foam density increases and insulative value decreases
Solution Approach 1:
The water-soluble polymer acts as a mediator that enables non-HCFC blowing agents to achieve adequate cell sizes, thereby maintaining insulative value while preserving environmental sustainability benefits
Solution Approach 2:
The invention creates a composite system combining the polymer melt, water-soluble polymer, and non-HCFC blowing agent. This composite approach allows the system to achieve both environmental sustainability and adequate insulative performance by synergistic interaction of components
3Volume of stationary object
If water is used as a blowing agent to enlarge cell size, then cell size increases and environmental sustainability improves, but corrosion of extrusion equipment increases
Solution Approach 1:
The water-soluble polymer serves as an intermediary between water and the polymer melt/extrusion equipment. It allows water to be effectively used as a blowing agent for cell size enlargement while minimizing direct contact between water and equipment, thereby reducing corrosion
Solution Approach 2:
The water-soluble polymer acts as a sacrificial protective layer that can be easily degraded or removed, protecting the expensive extrusion equipment from water-induced corrosion during the foaming process
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 allows for the production of foams with desired cell sizes without affecting the foam's properties, reduces corrosion, and maintains environmental sustainability by using low ozone-depleting and global warming potential blowing agents.
Implementation Method 1
introducing a liquid that evaporates or reacts under the influence of heat to form a gas directly into the second extruder and into the polymer melt, where the liquid is absorbed by the non-encapsulated porous carbon-containing compound
Implementation Method 2
introducing a liquid that evaporates or reacts under the influence of heat to form a gas
Data Source
AI summary
Polymeric foam and polymeric foam products that contain a foamable polymer material, at least one blowing agent, activated carbon, and water are provided. The activated carbon acts as both a water absorbent and carrier for the water. The activated carbon is able to control and increase cell size even in the presence of carbon dioxide, HFCs, and/or infrared attenuating agents. Additionally, the activated carbon permits a desired amount of water to be introduced into the polymer melt. By controlling the amount of activated carbon and its water content during an extrusion process, a broad range of cell sizes can be obtained in the extruded product. In exemplary embodiments, the activated carbon is added to a primary extruder and water is directly injected into a secondary extruder. Alternatively, the activated carbon is compounded with a polymer resin, pre-hydrated by conditioning or steam impregnation, and added to a primary or secondary extruder.