Progress 01/01/13 to 12/31/17
Outputs
Target Audience:Adhesives and engineered wood composites manufacturers, fellow scientists, and researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training an undergraduate student was provided in statistical and mechanical analyses. How have the results been disseminated to communities of interest?Results were published in a professional journal. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
ASTM shear-strength testing demonstrated that maximum average dry shear strengths were developed with the pine specimens bonded with the polyurethane (PUR) adhesive at minimum open and closed assembly times. In contrast, the lowest average shear strength was developed with the Douglas-fir specimens bonded with the same PUR adhesive and the same minimum open and closed assembly times. However, the majority of other average shear strengths were statistically similar and not affected by the adhesive or assembly times studied. Percent wood failure values were all above 75 percent, which is within acceptable limits and were found to be statistically similar across all variables studied. Both adhesives provided similar percent wood failure results on both wood types. Very high delamination measurements were found for the PUR adhesive assemblies for both wood types and all assembly times. In contrast, very small delamination values were measured for all specimens bonded with the phenol-resorcinol-formaldehyde (PRF) adhesive. However, it was determined that many of the averaged delamination values were statistically similar and no outstanding statistical differences could be found between the Douglas-fir and pine specimens. Although the number of trees were limited in this study, results indicated that southern yellow pine specimens generally developed higher dry shear strength values and lower delamination due to accelerated weathering tests, particularly with the PRF adhesive. Similar and extremely high delamination was measured for both wood types with the PUR adhesive, so no significant differences in bonding properties of the two wood types were observed with this adhesive. Both wood types and adhesives exhibited favorable bonding as measured with dry shear strength and percent wood failure. Expectations that the southern yellow pine specimens might provide less favorable bonding when tested in extreme weathering conditions were not confirmed with the wood bonding factors, adhesives, and assembly times tested in this study.
Publications
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:Adhesives and engineered wood composites manufacturers and researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training to technical personnel wasprovided for preparation of a manuscript targeted for peer review. How have the results been disseminated to communities of interest?Results were published in a peer reviewed scientific journal. What do you plan to do during the next reporting period to accomplish the goals?Project is complete within the next 2 weeks.
Impacts
What was accomplished under these goals?
Bonding properties of southern yellow pine and Douglas-fir (Pseudotsuga menziesii) were compared in terms of density, chemical composition, surface energy, shear stress, % wood failure, and delamination. Specimens were taken from two trees of loblolly pine and one tree of Douglas-fir. Density measurements showed that for mature wood, southern pine exhibited a higher average density than Douglas-fir but for juvenile wood, southern pine showed a lower average density than Douglas-fir. Chemical analysis determined that southern yellow pine contained a higher % of hemicellulose, lignin, and extractives while Douglas-fir had higher % cellulose. Static sessile drop contact angle measurements revealed that southern yellow pine specimens exhibited a lower average contact angle than Douglas-fir and accordingly, higher average surface energy. Shear strength, % wood failure, and delamination due to accelerated weathering were measured for bonded specimens constructed with either a one-part moisture cure polyurethane (PUR) or a two-part ambient curing phenol-resorcinol-formaldehyde (PRF) and three different assembly time combinations. Shear strength for southern yellow pine was affected the most by assembly time, whereas Douglas-fir shear strength was affected by the type of adhesive and interaction with the growth region at the bond. Delamination results showed that southern yellow pine exhibited less delamination than Douglas-fir when using PRF. Delamination measurements from the PUR bonds were similar and extremely high for both wood types. Although statistically significant differences were found in a few wood factors, limited differences were found in shear strengths, percent wood failure, and delamination due to accelerated testing for the twotypes of wood.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2017
Citation:
Myrable, K.V. and A. Zink-Sharp. 2017. Fundamental bonding properties of Douglas-fir and southern yellow pine wood. Forest Products Journal.
https://doi.org/10.13073/FPJ-D-17-00019
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Adhesives and engineered wood composites manufacturers, scientists, and researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Graduate student participated in writing the manuscript to be submitted for peer-review in a scientific journal. How have the results been disseminated to communities of interest?Peer-reviewed research journal. What do you plan to do during the next reporting period to accomplish the goals?Submit the journal manuscript, respond to reviews as needed, and secure publication.
Impacts
What was accomplished under these goals?
An extensive manuscript was prepared and is in the process of being submitted to a peer-reviewed scientific journal.
Publications
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:Adhesives and engineered wood composites manufacturers and researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training for graduate student in statistical and microscopic analyses was provided. How have the results been disseminated to communities of interest?Presentation made March 3, 2015, to industrial advisorial board, faculty colleagues, and prospective center members of the Wood-Based Composites Center, Blacksburg, VA. What do you plan to do during the next reporting period to accomplish the goals?Continue our laboratory research of the anatomical and chemical causes for the observed differences in bonding properties for these two wood types.
Impacts
What was accomplished under these goals?
Differences in southern yellow pine (represented by Pinus taeda) and Douglas-fir (Pseudotsuga menziesii) mature and juvenile wood were examined in terms of density, chemical composition, surface energy, shear stress, % wood failure, and delamination. Density was measured using a QTRS density scanner. Loblolly pine contained a higher average density. Chemical composition was measured using the NREL standard for identifying the chemical composition of biomass. Southern yellow pine contained a higher % hemicellulose, lignin, and extractives. Douglas-fir had higher % cellulose than southern yellow pine. Surface energy was measured using the static sessile drop contact angle method and the acid/base approach. Southern yellow pine contained a lower average contact angle than Douglas-fir. Shear stress, % wood failure, and durability were measured using ASTM-D2559 with two adhesives, a one-part moisture cure polyurethane (PU), and a two-part ambient curing phenol-resorcinol-formaldehyde (PRF). Shear stress for southern yellow pine was affected the most by the type of growth regions at the bond (juvenile to mature wood) and the assembly times of the adhesives used. Douglas-fir shear stress was affected by the type of adhesive with the growth region at the bond. Delamination results demonstrated that when using PRF the southern yellow pine has less delamination statistically than Douglas-fir. Also, the growth region at the bond with both adhesivesimpacted delaminations with juvenile to mature wood having less delamination than mature to mature wood.
Publications
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2015
Citation:
Mirabile, K. 2015. Investigating Differences between Douglas-fir and Southern Yellow Pine Bonding Properties. M.S. thesis. Virginia Polytechnic Institute and State University, Blacksburg, VA.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Audience includes researchers in the wood-based composites and adhesives industry and scientists in natural resources utilization fields. Efforts included informal educational programs, presentations at technical conferences, and laboratory instruction. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Training of one graduate student was provided through formal classroom instruction and laboratory training. A technician received one-on-one training for operation of a density scanning instrument. How have the results been disseminated to communities of interest? Project results have been presented at two wood-based technical conferences. What do you plan to do during the next reporting period to accomplish the goals? Testing of the bond durability and strength, statistical analyses of test results, and microscopic study of the bond lines will be completed.
Impacts
What was accomplished under these goals?
The findings in this project could lead to creation of new adhesive formulations for wood-based composites that have heretofore failed to meet certification requirements. Accomplishments include completion of surface characterization and chemical compositional experiments using two commercially important wood types. Scans of density within the wood specimens were completed. A review of a subset of the pertinent literature was prepared. Preparation of ASTM standard test specimens was near completion during this time period.
Publications
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: Target audiences include scientists, researchers, and technicians in the adhesives and wood composites industries. Changes/Problems: Aquisition of experiment specimens of Douglas-fir trees from Oregon has been delayed by harvesting, inclement weather, and shipping contraints. The delay will total approximately 6 months. What opportunities for training and professional development has the project provided? Training of one master of science study is in progress. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? Continue the exploration of influences of cellular and chemical composition on the adhesion properties and bonded assembly mechanical and durability properties. Specific tests include ASMT D905 bond strength tests, ASTM D5266 percent wood failure, and ASTM D2559 cyclic delamination tests. Complete the density scans, wettability, and compositional analysis experiments.
Impacts
What was accomplished under these goals?
Investigation of the density of various growth regions of southern yellow pine samples was designed and is in progress. This information is useful in determiming variability amongst and across the two wood types and the various growth regions under study in this project. Investigation of the surface energy of the two different woods has been designed and is in progress. Analysis of the chemical content differences between the two wood types has been started.
Publications
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