Progress 08/01/04 to 06/30/09
Outputs
OUTPUTS: The main body of outputs is encompassed by presentations that have been given at scientific, academic or industry meetings. They are listed below. Ruffing, T.C., W. Shi, N.R. Brown, and P.M. Smith. Improving Indoor Air Quality: Formaldehyde Emissions from Wood Composites. 2009 Build Green Conference. October 14-15, 2009. Philadelphia, PA. Ruffing, T.C., N.R. Brown, and P.M. Smith. Formaldehyde Emissions from Wood Products. School of Forest Resources Seminar Series. October 9, 2009. University Park, PA. Brown, N.R., T.C. Ruffing, W. Shi, and P.M. Smith. North American Resin Suppliers' Green Perspectives. Wood Adhesives 2009. September 28-30, 2009. Lake Tahoe, CA. Peer reviewed proceedings paper in development. Ruffing, T.C., P.M. Smith, N.R. Brown, and W. Shi. CARB Formaldehyde Emission Standards: An International Perspective. Wood Adhesives 2009. September 28-30, 2009. Lake Tahoe, CA. Peer reviewed proceedings paper in development. Smith, P.M., T.C. Ruffing and N.R. Brown. Green Resin Attributes in the Interior Wood Composite Panel Industry. Proc. of the 9th Pacific Rim Bio-Based Composites Symposium. Rotorua, New Zealand. 2008. Verma, V., N.R. Brown, W.O. Hancock, and J.M. Catchmark. Functionalized cellulose nanowhiskers for biological and nanocomposite applications. Presented at: 1) 5th Annual ESM Graduate Student Symposium. February 14, 2009. University Park, PA; and 2) 2009 Graduate Research Exhibition. March 29, 2009. University Park, PA. Brown, N.R. Adhesion Research at Penn State. Wood-Based Composites Center Meeting (Invited Guest Speaker). October 4-5, 2006. Blacksburg, Virginia. Brown, N.R., and J.M. Catchmark. Engineering Nanotechnology for Cellulosic Materials. 2006 BIO World Congress on Industrial Biotechnology and Bioprocessing (Invited Panelist). July 12-14, 2006. Toronto, Canada. Catchmark, J.M.,V. Verma, N.R. Brown, and W.O. Hancock. Impact of cellulose fiber organization and novel fiber assembly techniques. 2007 TAPPI International Conference for Nanotechnology in the Forest Products Industry. June 13-15, 2007. Knoxville, Tennessee. Beakler,B.W., P.R. Blankenhorn, N.R. Brown, and J. Wiedenbeck. Quantification of the Volatile Organic Compounds (VOCs) from Kiln-Drying Hardwood Lumber. 60th International Convention of the Forest Products Society. June 25-28, 2006. Newport Beach, California. Brown, N.R., and T.M. Gruver. Wetting and Penetration of PMDI Resin on Selected Wood Species. Engineered Wood Products Building the Future. (Forest Products Society). June 1-2, 2006. Fredericton, New Brunswick, Canada. Gruver, T.M., and N.R. Brown. Effects of Wood Species and Moisture Content on Structural Wood Composites Bonded with pMDI. Wood Adhesives 2005. Forest Products Society. November 2-4, 2005. San Diego, California. Brown, N.R. Co-monomer Location & Its Impact on Performance in Crosslinking Poly(vinyl acetate) Wood Adhesives. Beijing Forestry University. November, 2004. Beijing, China. Brown, N.R. Co-monomer Location & Its Impact on Performance in Crosslinking Poly(vinyl acetate) Wood Adhesives. Chinese Academy of Wood Science. November 2004. Beijing, China. PARTICIPANTS: Along with Dr. Brown, the following graduate students at Penn State participated in this work: Timothy Gruver, Brian Beakler, Thomas Ruffing, Wenping Shi, Yufan Zeng, and Vivek Verma. The following faculty at Penn State were collaborators: Dr. Paul Smith (Wood Products), Dr. Paul Blankenhorn (Wood Products), and Dr. Jeff Catchmark (Engineering Science and Mechanics Dept.). Dr. Vikram Yadama from Washington State University, Drs. Charles Frazier and Joseph Loferski from Virginia Polytechnic Institute and State University were collaborators, as were the following scientists at Bayer MaterialScience: Jone Cionni, Timothy Takah, Timothy McCracken and Dr. William J. Nicola. TARGET AUDIENCES: Outreach was done in the classroom at Penn State, to undergraduate and graduate students, as well as to scientists attending technical presentations. Envirothon and other similar events provided a platform to educate the general public regarding our activities. The publications include both national and international outlets for the scientific research. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Participants have been trained in the use of advanced scientific equipment. We have made gains in understanding the penetration of pMDI resin into wood, how the resin affects wood relaxations, and the effect of various isomer ratios of pMDI on its cure. We also better understand the performance of crosslinking poly(vinyl acetate) adhesives, and understand a bit more about the temperature dependent behavior of water-based wood adhesives. Work regarding formaldehyde emissions has led to a greater understanding of national and international policy on this subject, as well as a better understanding of the formaldehyde emissions from solid hardwoods. Work on nanocomposites has helped us to develop sample preparation techniques for future studies.
Publications
- Ruffing, T.C., N.R. Brown, J.S. Cionni, T. Takah, T.S. McCracken, and W.J. Nicola. 2009. Effects of Isomer Ratio on pMDI Resin Reactivity and Oriented Strandboard Properties 41(4):359-365.
- Graybill, A.E. and N.R. Brown. 2006. Influence of Radio Frequency Time on the Performance of Poly(vinyl acetate) Latex Adhesives. Wood Adhesives 2005. Forest Products Society. pp. 107-110.
- Gruver, T.M. and N.R. Brown. 2006. Macroscopic and Microscopic Considerations on the Effect of Wood Species and Moisture Content on pMDI/Wood Adhesion. Wood Adhesives 2005. Forest Products Society. pp. 123-125.
- Brown, N.R., J.R. Loferski, and C.E. Frazier. 2004. Co-monomer Location and its Impact on Performance in Crosslinking Poly(vinyl acetate) Wood Adhesives. Proceedings of the 7th Pacific Rim Bio-based Composites Symposium. Nanjing, China. pp. 166-73.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Several series of experiments were conducted to evaluate the cure chemistry of MDI resins having differing isomer ratios. It was thought that varying the isomer ratio would affect the cure time, and perhaps also the ultimate properties of bonded composites. Experiments were also conducted to evalute the use of a maleated polypropylene compound to improve water resistance in wood composite products. The composite materials were bonded with MDI resin. Neat chitin and cellulose composites were made and tested, along with chitin-cellulose-epoxy composites. Finally, work was undertaken to evaluate formaldehyde emissions from wood products. Results on each of the projects were presented at the annual Forest Products Society meeting. Projects were also described to students at various research seminars and during classes. PARTICIPANTS: Graduate students working on projects include Barun Gupta, Yufan Zeng, Thomas Ruffing, and Vivek Verma. Lauren Rega is an undergraduate who worked on the project. Jeff Catchmark is a co PI. Partnering organizations include Bayer MaterialScience (who provided facilities and collaborating scientists), Armstrong World Industries (who provided materials and collaborating scientists), Rohm and Haas (who provided materials, funding, and collaborating scientists) and the Pennsylvania Hardwood Development Council (who provided funding). TARGET AUDIENCES: Target audiences include the wood products and polymer industries. Knowledge gained in the most recent fiscal year has been disseminated in classroom instruction and laboratory instruction. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Knowledge was gained on experimental techniques, primarily utilizing the dynamic mechanical analyzer, differential scanning calorimeter, and the thermal gravimetric analyzer. Mechanical testing was also conducted, as was formaldehyde emission measurents. Students developed new procedures for the instruments in order to evaluate properties of interest. Students were trained on this equipment and acquired skills in using the equipment properly.
Publications
- Gruver, T.M., N.R. Brown, J.S. Cionni, T.S. McCracken, W.J. Nicola, and T. Takah. 2008. Effects of Selected Wood Species and Moisture Content on pMDI Resin Application and Panel Properties. Wood and Fiber Science. 40(2): 242-247.
- Beakler, B.W., P.R. Blankenhorn, N.R. Brown, M.S. Scholl, and L.R. Stover. 2007. Quantification of the VOCs from Kiln Drying Red Oak and White Oak Lumber (Part I). Forest Products Journal. 57(11):27-32.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: During 2007, a number of topics were addressed relating to diphenylmethane diisocyanate (pMDI) adhesives and poly(vinyl acetate) adhesives (PVAc). We conducted further work (chiefly statistical analysis) on the observed interaction of pMDI with certain wood species. We also investigated blended pMDI resins containing various ratios of (2,4 and 4,4 MDI content). To increase the water-resistance of oriented strand board, we did a project to explore the inclusion of various maleated polypropylenes (MAPP), particularly when the OSB was made with pMDI resin. On the waterborne side, we did a study to evaluate the temperature-dependent performance of PVAc bondlines. New work was begun on two subjects that relate only peripherally to wood adhesives: cellulose-rich composites and formaldehyde emissions from wood. Results have been and will continue to be disseminated principally through presentations at conferences and publications. Most of our publications are still in development.
We did conduct one wood adhesion short course at Pittsburgh Paints and Glass (PPG), designed to give them a better understanding of wood as a substrate. We also provided an overview of our research to Rohm and Haas (RH).
PARTICIPANTS: Timothy Gruver, Thomas Ruffing, Barun Gupta, and Yufan Zeng were all students who participated in the project. Partnering organizations included Bayer MaterialScience, the York Group, Conestoga Wood Products, and Armstrong World Industries.
TARGET AUDIENCES: The chief target audience for this project is the adhesives industry, which is a sizable component of the Chemical Industry. Other audiences include scientists who work in research and development on adhesives, polymers and composites, as well as the wood products industry.
Impacts
This project is rooted in fundamental science. Important gains in knowledge or new product development can lead to industrial implementation. At this stage, we have no industrial implementation, but we have learned important aspects of adhesive cure chemistry and morphology. In the case of the species-dependent performance of pMDI resin, our work led to interesting observations regarding isocyanate resin penetration into wood substrates; specifically, that penetration is highly dependent upon substrate species and moisture content. When evaluating resins with differing 2,4 and 4,4 MDI contents, we confirmed that resin with the largest amount of the 2,4 isomer had the slowest cure kinetics, as expected. We are still in the process of evaluating the MAPP data, and the temperature dependence of the PVAc adhesives. Our outreach efforts to PPG and RH were positively received, and we look forward to other opportunities to share knowledge with industry.
Publications
- Brown, N.R. and C.E. Frazier. 2007. Cross-linking Poly[(vinyl acetate)-co-N-methylolacrylamide] Latex Adhesive Performance: Part I, N-methylolacrylamide (NMA) Distribution. International Journal of Adhesion and Adhesives. 27:547-553.
- Brown, N.R., J.R. Loferski, and C.E. Frazier. 2007. Cross-linking Poly(vinyl acetate-co-N-methylolacrylamide) Latex Adhesive Performance: Part II, Fracture Mechanics and Microscopic Durability Studies. International Journal of Adhesion and Adhesives. 27:554-561.
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Progress 01/01/06 to 12/31/06
Outputs
During 2006, several studies have been undertaken or completed regarding wood-adhesive behavior. These studies include: 1.)varying isomer (2,4' vs 4,4') content in pMDI resins, 2.)effect of wood species on the performance of pMDI resin, 3.)selected coupling agents in conjunction with epoxy and polyvinyl acetate adhesion, 4.)effect of RF cure times on polyvinyl acetate performance and 5.)effect of varying humidity on polyurethane adhesive cure. During 2006 one student graduated with a master's degree, and three undergraduate students have been involved in related research projects. Two of the projects mentioned above were based on understanding pMDI resin performance. To understand the species dependence of pMDI resin, we conducted compression shear block testing, fluorescence microscopy, and dynamic mechanical analysis experiments. The experiments gave us a better understanding of the performance of pMDI resin when applied to wood substrates having different pre-cure
moisture contents. Fluorescence microscopy and dynamic mechanical analysis allowed micron to nanometer scale penetration of pMDI to be explored, as a function of both species and pre-cure moisture content. Varying the proportion of 2,4' pMDI isomer was expected to affect cure time during the manufacturing of OSB panels. Physical testing was done on a series of OSB panels. The following tests were conducted: edge swell, thickness swell, modulus of elasticity, modulus of rupture, and density measurments. Differential scanning calorimetry work is currently being conducted, and this aspect will continue into 2007. The application of selected coupling agents to wood was investigated as a function of the delay time. Various delays were employed (between coupling agent application and adhesive application) to investigate the time sensitivity of the coupling agents. Compression shear block tests were then used to probe adhesive performance. Polyvinyl acetate and epoxy adhesives were used. To
evaluate the effects of varying radio frequency exposure time, edge glued panels were also investigated via compression shear block tests. These panels were prepared at an industrial manufacturing site and were tested in our laboratory. Small sections of the bondlines were also investigated via dynamic mechanical analysis studies. Finally, a project has just begun on the effect of varying wood moisture content on the cure of polyurethane adhesives.
Impacts
As smaller diameter trees are being harvested, adhesive utilization is increasing in order to meet societal demands for large wood products. This work provides an understanding of the influence of adhesives on wood, and characterizes the molecular interactions of wood with adhesives, coupling agents, and other chemical treatments. Our research will help promote more durable wood products for homeowners.
Publications
- Gruver, T.M. and Brown, N.R. 2006. Penetraton and Performance of Isocyanate Wood Binders on Selected Wood Species. Bioresources Journal. 1(2): pp. 233-47.
- Gruver, T.M., Brown, N.R., Cionni, J.S., McCracken, T.S., Nicola, W.J., and Takah, T. 2006. Investigation of Wood Species and Moisture Content on pMDI Resin Application and Panel Properties. Proc. of the 29th Annual Meeting of the Adhesion Society. pp. 184-186.
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Progress 01/01/05 to 12/31/05
Outputs
This year three major areas of interest have been investigated. Isocyanate resin and its associated species-dependent performance issues, coupling agents for wood adhesion, and the effect of radio frequency cure time on joint durability. Isocyanate resin, specifically the species-dependent performance of the resin, has been studied. This research included three different wood species: yellow-poplar, aspen, and southern yellow pine. The wood blocks were equilibrated to one of three moisture contents: 0%, 5% or 12% before resin application. Mechanical tests (compression shear block tests) of bonded specimens were completed, as were cure studies using dielectric analyses. Fluorescence microscopy was used to investigate resin penetration into wood substrates, and interesting differences were observed. In addition to these bulk wood studies, waferboard composites were manufactured using the isocyanate resin. Again, species and moisture effects were examined. Tests were
conducted on the composite samples to measure sample modulus of elasticity, modulus of rupture, edge swelling, and internal bond strengths. Results of these studies will be published in upcoming articles. This project is continuing with the investigation of the viscoelastic properties of wood-resin composite specimens. This work will be completed on a dynamic mechanical analyzer. A second subject investigated this year was coupling agents and their influence on wood adhesion. A series of three coupling agents were tested on both polyvinyl acetate and epoxy adhesives. Tests are still ongoing on this project. Finally, work began on a third topic; the influence of radio frequency cure time on adhesive joint durability. This was probed with both compression shear block and DMA tests. This study is also ongoing.
Impacts
As smaller diameter trees are being harvested, adhesive utilization is increasing in order to meet societal demands for large wood products. This work provides an understanding of the influence of adhesives on wood, and characterizes the molecular interactions of wood with adhesives, coupling agents, and other chemical treatments. Our research will help promote more durable wood products for homeowners.
Publications
- Brown N.R. and Frazier, C.E. 2005. Synthesis of Labeled Acrylamide and N-methylolacrylamide (NMA): 15N-acrylamide, 13C-NMA, 15N-NMA, and 13C,15N-NMA. Journal of Labelled Compounds and Radiopharmaceuticals. 48: 1031-1039.
- Gruver, T.M. and Brown. N.R. 2005. Penetration and Performance of pMDI Resin on Selected Wood Species. Proc. of the 28th Annual Meeting of the Adhesion Society. 483-485.
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Progress 08/01/04 to 12/31/04
Outputs
Project is in initial phases. Experimental apparatus have been set up, and a student has been trained on proper methods for operating the equipment. Preliminary samples, including a variety of wood species, adhesive samples, and wood blocks treated with adhesives, have been analyzed. Studies that have begun have included: softening temperature of poly(vinyl acetate) adhesives, rheology of poly(vinyl acetate) adhesives, and compression shear block testing of various poly(vinyl acetate) adhesives. Wood-isocyanate resin interaction studies will begin shortly. To date, no significant findings are available.
Impacts
Poly(vinyl acetate) adhesives are widely used in wood bonding. Rheological studies can help determine the shelf life of these adhesives. Likewise, softening temperatures of wood-adhesive joints have a commercial impact. Currently, some wood manufacturers are purchasing bonded wood, but the joints are failing because their processing conditions require high temperature treatments. This study will determine the maximum temperature limits for this type of adhesive. Isocyanate adhesives are used to make many composites. However, they have shown evidence of species-dependent behavior. This project will study the effect of different wood species and their interactions with the adhesive.
Publications
- No publications reported this period
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