Grantee Research Project Results
Final Report: Formulation and testing of an entirely wood-based exterior insulation board for the high-performance building market
EPA Contract Number: 68HE0D18C0024Title: Formulation and testing of an entirely wood-based exterior insulation board for the high-performance building market
Investigators: Henry, Dr. Joshua A
Small Business: GO Lab
EPA Contact: Richards, April
Phase: I
Project Period: October 1, 2018 through March 31, 2019
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2018) RFA Text | Recipients Lists
Research Category: SBIR – Sustainable Materials Management , Small Business Innovation Research (SBIR)
Description:
Go Lab is developing Insulating Wood Fiber Composite (IWFC) products made of 90-95% softwood fiber that can be used in commercial and residential buildings as an interior and exterior insulation. The company was founded in 2017 with a mission to research, design, and go to market with new building materials that are renewable, sustainable, and better for the environment, without sacrificing performance. The core of the mission is to remove the premium that is charged for “green” products and sell the products in the U.S. at a price competitive with foam and fiberglass, the two products that make up 90 percent of the U.S. Market today.
IWFCs are pressed composite boards made predominantly from softwood fibers and sold commercially in Europe as a rigid exterior insulation and are used to give buildings a continuous layer of insulation just underneath the siding. Globally, the rigid insulation board market is dominated by rigid polystyrene boards, which have good insulating properties and are relatively inexpensive, but are not recyclable, made from fossil fuels, are flammable, toxic and have high embedded energy. The introduction of IWFC insulation to the North American Market would provide an economically viable and more environmentally friendly option for designers, builders and customers.
The only ingredient of the currently existing European wood fiber insulation that is not renewable is the binding agent – pMDI (polymeric Methylene Diphenyl Diisocyanurate). It is made from petro-chemicals. As well as being non-renewable, there are some health hazards associated with pMDI as it is administered during the manufacturing process. As stated on the SDS, it is harmful if inhaled and can cause respiratory irritation. Due to this, a very robust ventilation system is needed in manufacturing.
Summary/Accomplishments (Outputs/Outcomes):
In Phase I of the EPA SBIR, GO Lab worked on developing and testing a new “recipe” for low density wood fiber insulation that omits pMDI altogether, so that the product will be 100% nontoxic, 100% renewable, 100% sustainable. GO Lab experimented with two alternative binders which are renewable. One is a nanocellulose binder and one is a binder made from sugar and starch called ECOSE. Each of these binders have never been used to create wood fiber insulation before, so GO Lab tested to see if these will be appropriate and effective in these insulating products and enable us to make a very healthy, safe, non-toxic product that has exceptional physical and thermal properties.
One of the most exciting results of the Phase I research is that we discovered that the nanocellulose binders has the ability to create a board product with extremely low density (which makes for the best insulation) and high compressive strength. This is a huge advantage when looking at the commercialization applications because it creates a lighter insulation product which in turn, makes it easier for contractors and homeowners to install. That will be a huge market advantage. In fact, the insulating board with the nanocellulose binder is not just an equivalent replacement for foam board or mineral wool boards, but it is a major improvement over the available products due to the physical characteristics.
GO Lab’s Phase I proposal has three technical objectives: 1) to create an optimized process for producing insulating wood fiber composites (IWFCs) with material properties comparable to commercial IWFCs in Europe, 2) formulation and testing of an insulating nanocellulose-wood fiber composite and 3) the replacement of pMDI with a renewable polymer system without compromising the composite properties. For the most part, with the partial exception of (1) – all objectives were met and explained below.
In part, objective (1) was a success because a much broader range of low-density samples with greater R-values were produced. The success was only partial because across a range of densities, the composites produced had an R-value that was roughly 15% lower than identically formulated commercial products. The origins of this discrepancy require further study, but a few factors could be to blame.
The first factor is that the samples produced at the Advanced Structures and Composites Center (ASCC) were made from hand formed mats, whereas the mats in a commercial manufacturing line are mechanically formed. Mechanical formers break up clumps of fibers that naturally form after the application of the pMDI. This significantly effects the microscale structure of the composite so that instead of getting the ideal continuous composite, a composite of bonded, millimeter scale fiber balls are formed. This likely would not only lead to poorer R-values because of the large empty spaces in the material, but poorer internal bond strengths. To give weight to this potential hypothesis, GO Lab has ordered commercial product of varying densities to be tested by the ASCC for internal bond strength in order to establish a benchmark upon which laboratory samples can be measured.
The second potential factor is that to complete this study in the allotted timeframe, GO Lab had to ship wood fiber from Europe that had been treated with boric acid as a fungicide.The only chemicals used in the production of commercial insulating wood fiber boards in Europe are pMDI as an adhesive and paraffin as a water repellant. Although it seems an unlikely culprit, if awarded the SBIR Phase II, Go Lab will obtain domestically produced wood fiber that does not need to be treated prior to shipping and re-test this.
Trials aimed at producing low density fiberboard samples using nanocellulose as the binder were similarly successful. Samples with a range of board densities were produced and resulted in R-values very consistent with the samples produced in objectives 1 and 3. Three binder loads were investigated: 20%, 10% and 5% by weight. It was found that only 5% CNF was adequate to produce structurally sound products with a density of as low as 0.10 g/cm3. As expected, an overall negative correlation between the density and R-value was observed. Upon complete water removal, a hard outer layer is formed on the surface of the panel. This layer can be removed during trimming or sanding without affecting the structural integrity of the panel. Scanning electron microscopy images revealed the difference in pore structures for low, medium, and high-density panels. The images also showed that the dense domains were located towards the edges while the less dense domains were located in the center, especially in the low-density panels. This core-shell structure seems to impart impressive compressive strength to the products - almost twice as much as synthetic resins at the same density.
What is different and exciting about these results is that prior to these trials nanocellulose had only been used as a binder in higher density wood composites. That was in part due to the fact that nanocellulose’s activity as a binder is attributable to intermolecular forces and had the propensity to densify composites as they cured/dewatered. The procedure developed for these samples, which is in the process of being patented, avoids this result while apparently enhancing mechanical properties relative to both ECOSE and pMDI. The substantially enhanced compressive strength at lower densities is particularly exciting because it suggests the possibility of board with foam-like densities, R-values and compressive strengths, but made from entirely renewable materials.
Conclusions:
In terms of commercial applications, these improved characteristics have the potential to disrupt a very mature market for insulation by producing something that is fully renewable but that also has superior physical properties. If the research from EPA SBIR I can be further developed and commercialized, GO Lab will be unique in the market by producing a “green” product which is superior for the environment, price competitive with the lowest price alternatives, and has vastly superior physical properties to foam, fiberglass and mineral wool.
Finally, the primary result from GO Lab’s third research objective was that fiberboard samples made from ECOSE, a renewable polymer system made from the reactions of renewable carbohydrates (i.e. sugars) and polyamines. What were able to demonstrate in this project was that boards made with ECOSE can have material properties as good as samples made with pMDI, but require greater binder concentrations and longer press times. Both concentration and press time have a direct impact on the viability of ECOSE as a commercial adhesive. In wood composites the binding agent is generally the most expensive input and therefore the less required (i.e. lower concentration) the better. Press time effects the speed of the manufacturing process – the longer the press time, the lower the productivity of the manufacturing line, which directly impacts gross revenue.
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.