Grantee Research Project Results
Final Report: Development of Passive Humidity-Control Materials
EPA Grant Number: R830420C003Subproject: this is subproject number 003 , established and managed by the Center Director under grant R830420
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Center for Environmental and Energy Research (CEER)
Center Director: Earl, David A.
Title: Development of Passive Humidity-Control Materials
Investigators: Carty, William , Sinton, Chris
Institution: Alfred University
EPA Project Officer: Aja, Hayley
Project Period: July 1, 2004 through June 30, 2006
Project Amount: Refer to main center abstract for funding details.
RFA: Targeted Research Center (2002) Recipients Lists
Research Category: Congressionally Mandated Center , Targeted Research
Objective:
It has been proposed that ceramic monoliths offer a unique opportunity as a passive humidity control material provided the pore size and pore structure can be engineered. The objective of this research project was to determine the feasibility of generating ceramic monoliths with controlled pore size in the range appropriate for the condensation of water at a specific humidity level. It also is necessary that the pore volume in the sample be sufficient to contain a reasonable volume of condensed water. A unique approach to porosity control in ceramic materials is proposed that exploits the phase separation observed when two or more incompatible polymeric additives are used in a ceramic particle suspension.
The direct benefit of this research project was to produce ceramic monoliths with controlled pore size and sufficient pore volume, which serve as the passive humidity control materials. The humidity control materials do not replace the current humidity control methods but offer the potential for significant savings in both heating and cooling costs. This successful introduction of the humidity control materials will substantially impact the use of building materials and energy conservation.
Summary/Accomplishments (Outputs/Outcomes):
Recent studies showed that polymeric additives used in ceramic processing interact and influence the morphology of final products (Sundlof, 1999; Kim, 2002). When the interactions between polymers are non-associative or repulsive, phase separation can occur, leading to pores in a ceramic matrix (Approach I). A polyelectrolyte (Polymer 1), which is used to disperse ceramic particles in water, adsorbs on the surface of particles, and the ceramic particles appear as large domains of polyelectrolyte. With the start of phase separation by adding an incompatible polymer (Polymer 2) into the system, particles covered with polyelectrolyte tend to form an interconnected structure to reduce the free energy of the system. Strong attractive interaction acts between the particles to reduce the interface area with another polymer phase. The process to form an interconnected structure of ceramic particles is facilitated with shrinkage during the drying process. The pore size can be controlled by the molecular weight of the second polymer, which forms phase separated areas in a suspension and results in pores in the matrix after firing. The pore connectivity also can be controlled by the concentration of the second polymer. The phase separated areas grow with an increase of polymer concentration.
Pores also can be developed by the associative interactions between two polymers (Approach II). If a polymer adsorbed on ceramic particles associates with the second polymer, the associated polymers on ceramic particles can be phase separated from a solvent. After firing pores are generated from the areas where a solvent takes up in a slurry state.
These two approaches were employed to develop ceramic monoliths with controlled pores. For Approach I, polyacrylic acid of ammonia salt (PAA) is used to disperse ceramic particles in water, and PEG, polyethylene oxide (PEO), or PVA is introduced to induce phase separation in the system. The properties of all the polymers in an aqueous system are very well established and a wide range of molecular weight of PEG exists commercially. The effect of three variables including solid content, polymer concentration, and molecular weight of PEG on porous structure development are investigated. For Approach II, sodium silicate is used to disperse ceramic particles and again polyethylene glycol (PEG) or polyvinyl alcohol (PVA) is introduced to induce associated phase separation in the system.
This research project indicated that a porous structured ceramic matrix can be developed by the proposed approaches (Approach I and II). Ceramic particles coated with PAA formed domains of interconnected structure, and a second polymer (PEG, PEO, and PVA) formed a morphology by bicontinuous type phase separation, leading to ad channel structure around domains after firing. The associate reaction between sodium silicate adsorbed particles and PVA resulted in phase separation from a solvent and developed a porous structure.
In Approach I, channel structures formed by phase separation was related to the concentration and molecular weight of a second polymer; the channel structure expanded with the increase of polymer concentration and molecular weight. Partial surface coverage of ceramic particles with PAA resulted in larger domains of interconnected structure as a result of the flocculation of ceramic particles. With the increase of total solids content, the porous structure became homogeneous through the body in the tested range of solids content.
The mixing of boehmite with alumina generated a distinctive microstructure depending on the ratios between them. From the developed microstructure, it is suggested that boehmite particles in the nano-size range may act as a medium for alumina particles in a slurry state and help maintain particle structure during drying and firing processes.
Approach II also was proven to be a very effective method for the development of porous structure. The microstructure indicates further densification in the samples prepared with sodium silicate due to the Na-salts dissociated from sodium silicate.
The results also provide insights into the fundamental studies in ceramic processing. The ceramic morphology control by the interactions between polymeric additives is a relatively new idea in ceramic processing. The results generated from this research project established the relationship between pore structure and concentration and molecular weight of polymer. This extends the project on particle phase behaviors in a dilute suspension to a concentrated system, which is close to the suspensions in mass production. The results obtained from this research project can be applied to other areas that require controlled pore size and volumes with strength such as biomaterials and catalysts and can lead to more research opportunities in those areas.
References:
Sundlof BR. Aqueous processing of alumina and phase behavior of polymeric additives. Ph.D. Dissertation. Alfred University, Alfred, NY, 1999.
Kim U. The role of polymer compatibility in ceramic processing. Ph.D. Dissertation. Alfred University, Alfred, NY, 2002.
Supplemental Keywords:
pore, porous structure, alumina, boehmite, polymer, phase separation, polymer interaction, PEG, PEO, PVA, PAA, sodium silicate, technology for sustainable environment, glass technology, sustainable industry/business,, RFA, Scientific Discipline, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Sustainable Industry/Business, POLLUTION PREVENTION, Sustainable Environment, Energy, Technology, Technology for Sustainable Environment, Environmental Engineering, clean energy, energy conservation, clean technologies, cleaner production, sustainable development, environmental conscious construction, clean manufacturing, glass microspheres, energy efficiency, energy technology, alternative fuel, photo enhanced hydrogen diffusion, alternative energy sourceRelevant Websites:
http://ceer.alfred.edu/ Exit
http://ceer.alfred.edu/Research/passivehumidity.html Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R830420 Center for Environmental and Energy Research (CEER) Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R828737C001 Environmental Impact of Fuel Cell Power Generation Systems
R828737C002 Regional Economic and Material Flows
R828737C003 Visualizing Growth and Sustainability of Water Resources
R828737C004 Vibratory Residual Stress Relief and Modifications in Metals to Conserve Resources and Prevent Pollution
R828737C005 Detecting and Quantifying the Evolution of Hazardous Air Pollutants Produced During High Temperature Manufacturing: A Focus on Batching of Nitrate Containing Glasses
R828737C006 Sulfate and Nitrate Dynamics in the Canacadea Watershed
R828737C007 Variations in Subsurface Denitrifying and Sulfate-Reducing Microbial Populations as a Result of Acid Precipitation
R828737C008 Recycling Glass-Reinforced Thermoset Polymer Composite Materials
R828737C009 Correlating Clay Mineralogy with Performance: Reducing Manufacturing Waste Through Improved Understanding
R830420C001 Accelerated Hydrogen Diffusion Through Glass Microspheres: An Enabling Technology for a Hydrogen Economy
R830420C002 Utilization of Paper Mill Waste in Ceramic Products
R830420C003 Development of Passive Humidity-Control Materials
R830420C004 Microarray System for Contaminated Water Analysis
R830420C005 Material and Environmental Sustainability in Ceramic Processing
R830420C006 Interaction of Sealing Glasses with Metallic Interconnects in Solid Oxide and Polymer Fuel Cells
R830420C007 Preparation of Ceramic Glaze Waste for Recycling using Froth Flotation
R830420C008 Elimination of Lead from Ceramic Glazes by Refractive Index Tailoring
R830420C010 Nanostructured C6B: A Novel Boron Rich Carbon for H2 Storage
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.