Grantee Research Project Results
Final Report: Robust, Nontoxic, and Environmentally Friendly Replacements for PentaBDE, OctaBDE, and Other Halogenated Fire Retardants
EPA Contract Number: EPD05020Title: Robust, Nontoxic, and Environmentally Friendly Replacements for PentaBDE, OctaBDE, and Other Halogenated Fire Retardants
Investigators: Bunnell, H. Dean
Small Business: Thermolose Cellulose Products, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2005 through August 31, 2005
Project Amount: $69,737
RFA: Small Business Innovation Research (SBIR) - Phase I (2005) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , Hazardous Waste/Remediation , SBIR - Waste
Description:
The purpose of the research conducted in this Phase I project was to develop a nontoxic and environmentally friendly cellulose-based fire retardant (FR) material that could replace brominated and other toxic FRs.
Summary/Accomplishments (Outputs/Outcomes):
Thermolose Cellulose Products Inc. began its project with a detailed investigation of the aqueous phosphoration of hydroxyethyl cellulose (HEC) with diammonium phosphate (DAP), a common and nontoxic FR, and evolved into using a common starch as the base polymer and another form of readily available phosphate.
Initial research produced cellulosic polymer films and solids that were mechanically strong and which also exhibited robust FR properties.
Additional testing of the cellulose polymer material demonstrated four undesirable attributes:
- The material exhibited a high degree of hydroscopicity
- Salt creep or migration of the DAP out of the HEC polymer base
- Mechanical properties of the resultant material made it very difficult and potentially expensive to produce a powdered version of the FR
- The resultant material supported bioactivity
To address the hydroscopicity and salt creep, other nontoxic forms of phosphates were examined as replacements for the DAP. Water-soluble ammonium polyphosphate (APP) was found to be a suitable replacement for DAP. To solve the mechanical problem of producing the FR in a powder form and because of the chemical similarity of starch and cellulose, various forms of starch were investigated. Other hydrocolloids were also investigated and found not to be suitable for this application because of raw material costs.
The use of water-soluble APP eliminated the salt creep observed with DAP, and moving from cellulose to starch as the base polymer solved the mechanical problems of producing a powdered FR.
One problem remained at this point — the hydroscopic nature of the FR material. Solving the hydroscopic problem required moving away from an aqueous process to a near-dry process and utilizing a less-soluble form of APP.
The bioactivity problem was addressed by using common and nontoxic food additives (sodium benzoate and methyl paraben).
This redesign of the associated chemistry and processes produced an FR material that demonstrated:
- Elimination of the salt creep problem
- A significant reduction in hydroscopic behavior
- Potential control of bioactivity
- A resultant material that could easily be produced in a powder form
- Significant reduction in process costs
Conclusions:
The dry powder FR materials produced as a result of this Phase I project have the potential to be used successfully in a variety of building materials, including various wood products, acoustic ceiling tile, polyurethane foam, gypsum, various coatings such as acrylic latex paints, and other applications including carpet backing, various fabrics and insulation materials.
Additional testing and development is necessary to completely characterize the FR material and refine the near-dry manufacturing in order to scale up and move the FR material forward into a commercialization.
The FR material is currently being evaluated in a variety of building material applications including the following:
Oriented Strand Board (OSB)
Thermolose has executed a nondisclosure agreement (NDA) with an OSB manufacturer. The two companies are working together to determine if the FR material produced as a result of this project could be used to produce an OSB product capable of achieving a Class A flame spread rating.
The manufacturer is continuing to evaluate the FR and determine the optimal process application and loading level necessary to obtain a Class A flame spread rating for its product. The manufacturer has requested an estimate of the price of the FR and a 3-ton sample to conduct a beta test in a factory production line.
Fiberboard
Thermolose has executed an NDA with a fiberboard manufacturer. The two companies are working together to determine if it is possible to improve the flame resistance of the fiberboard and achieve a Class A flame spread rating so that the fiberboard can be used as roofing panels. Initial testing shows that there is no conflict with the associated chemistries and processes involved in fabrication of the fiberboard.
The fiberboard manufacturer is continuing to evaluate the FR and determine the optimal process application loading level necessary to obtain a Class A flame spread rating for its product. The manufacturer has requested an estimate of the price of the FR and a 2-ton sample to conduct a beta test in a factory production line.
Gypsum
Thermolose has executed an NDA with a gypsum wallboard manufacturer. The two companies are working together to determine if the FR material can increase the thermal resistance of wallboard to improve its ability to withstand exposure to high heat and direct flame.
Initial laboratory testing indicates that the FR material can in fact be incorporated into the gypsum powder prior to casting the material. Incorporation of the FR requires incorporating additional water into the gypsum slurry. Although the FR can be incorporated into the slurry, the amount of water required to produce a level of fluidity suitable for casting is not compatible with the drying process used to remove water from the gypsum slurry prior to paper cladding the product. Additional research would be required to develop a suitable manufacturing process.
Rigid Polyurethane Foam
Thermolose has executed an NDA with a producer of polyurethane foam components and foam products. The two companies are working together to determine if the FR can improve the flame resistance of the rigid polyurethane foam (RPUF) material.
Thermolose conducted experiments to determine if the FR was compatible with the foam chemistry and if it could be used to fire-retard RPUF. Thermolose introduced the FR into the liquid components of the rigid foam prior to mixing and expanding the foam. The FR can be introduced into either the isocyanate or the polyol foam components; moreover, it works well when added to either component. The polyol is the preferred component.
The FR material did not interfere with the foam chemistry. The treated foam exhibited dramatically improved ability to resist exposure to direct flame. The treated foam did not melt or drip when exposed to direct flame. Although there was minimal flame support, the material quickly extinguished when the flame source was removed. The treated foam formed a mechanically stable char. There was a very significant reduction of smoke, soot and the generation of volatile organic compounds.
There was an unexpected result of introducing the FR into the foam. The FR acts as a blowing agent and inflated the foam. The resulting foam cell structure was dense and uniform and did not seem to compromise the mechanical properties of the resulting foam.
Paint
Cursory laboratory work was done to test the feasibility of incorporating the FR into a typical paint, such as a commercially available acrylic latex product. Testing is in the early phase. Initial results show that the chemistries seem to be compatible and that the treated paint does show a reduction in flammability. More testing and evaluation is required. No outside evaluation work is being done in the application area at this time.
Additional work is needed to fully characterize the starch FR material, scale up and refine manufacturing processes, as indicated below:
Chemical and Mechanical Characterization of the FR Material
To date, testing and characterization of the FR material has focused on examining and resolving specific property related issues — both mechanical and chemical.
Further work is needed to fully characterize the FR material and optimize its properties and associated use processes.
To complete the chemical and material characteristics of the FR, the following testing needs to be carried out:
- Insect activity
- Storage stability
- Accelerated life test
- Ultraviolet tolerance
- Other mechanical and chemical properties as required
Process Refinement
Currently, there are two specific near-dry processes that have been developed to produce the starch-based FR. FR material has been produced utilizing both of these processes in the pilot facility of a starch manufacturer that Thermolose is working with. These processes are common to starch manufacturing and food processing.
Each process has specific attributes that must be taken into consideration in order to select and optimize the process that will be adopted, to allow for the best possible economic value added (EVA) outcome for attempting commercialization of the FR product. A description follows:
- Process A
- Pros: This process has a very high throughput capability, low cost of operation, and is ideally suited for large-scale manufacturing. This process is energy efficient and produces no waste stream.
- Cons: One aspect of this process is that it currently causes more gelation than the other process that has been identified. This increased gelation causes the starch polymers to be slightly more likely to absorb water when the FR is introduced into a water-based system for application or compounding.
- Note: The working parameters of this process (time, pressure and temperature) are currently being adjusted in an attempt to reduce the gelation and, therefore, the tendency to absorb water in a static swell test. More work is needed to optimize this process.
- Process B
- Pros: This process results is less gelation than Process A. The FR material produced in this process exhibits the least amount of static swelling in room-temperature water.
- Cons: This process is less efficient than Process A.
Supply Chain Development
To date, Thermolose has identified a starch manufacturer with the capability and capacity to supply market demand for a nontoxic and environmentally friendly FR. Once the FR has been optimized and it has been determined to perform to market expectations and fit within the cost structure of potential users, the relationship will be formalized and moved forward. The starch manufacturer has filed for a Toxic Substances Control Act (TSCA) number for the starch FR.
Thermolose needs to formalize a relationship with this company once potential users in the marketplace have validated the product. An NDA and a memorandum of understanding (MOU) are currently in place and talks have been initiated to take the working relationship to the next level.
Thermolose is also sourcing the specific form of APP that has been found to work the best in the formulation of the FR product. Each source of the APP is being evaluated for price, availability, on-time delivery and staying power in the marketplace. The goal is to identify and engage at least two reliable and cost-effective APP sources.
As part of its commercialization strategy, Thermolose is working to identify early adopters that have an immediate need for an FR such as the one that the company is currently developing. The strategy is to engage with targeted users to establish a high-quantity level use rate as rapidly as possible. Additional testing and characterization of the FR is essential to initiating and developing these relationships.
Product Costing
Given the commodity nature of the FR market, it is essential that Thermolose and its potential manufacturing partner know and understand all attributes of product cost and are able to position the product in a manner so as to demonstrate the EVA and achieve rapid market penetration. Once a decision has been reached with respect to which manufacturing process is best for the product, accurate costing will be carried out as the manufacturing process is scaled up.
Further Beta Site Testing
More testing and characterization is needed to move forward with the potential customers Thermolose is currently working with. In addition to full characterization of the chemical and mechanical properties of the FR, the processes used to manufacture the FR will likely be optimized around the requirement of the potential customers currently involved in beta testing and other early adopters.
Summary Comment
In this Phase I project, Thermolose has demonstrated the feasibility of producing a robust, nontoxic and environmentally friendly starch-based FR capable of replacing brominated and other toxic FRs. The resultant FR material produced in this project utilized common materials and manufacturing processes currently in place in the starch-manufacturing environment. Potential customer response has been positive and feedback from sample testing is very encouraging.
Supplemental Keywords:
nontoxic, fire-retardant material, cellulose polymer, hydroxyethyl cellulose, diammonium phosphate, ammonium polyphosphate, oriented strand board, Class A flame, fiberboard, gypsum, rigid polyurethane foam, economic value added, gelation, Toxic Substances Control Act, EPA, small business, SBIR,, RFA, Scientific Discipline, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, POLLUTANTS/TOXICS, Sustainable Industry/Business, Chemical Engineering, Sustainable Environment, Environmental Chemistry, Technology, Chemicals, Technology for Sustainable Environment, Chemicals Management, Environmental Engineering, PentaBDE alternative, clean technologies, environmentally conscious manufacturing, green design, VOC removal, alternative materials, alternative flame retardant, hybrid polymers, pollution prevention, Volatile Organic Compounds (VOCs), OctaBDE alternativeThe 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.