Graduate Thesis Or Dissertation
 

Sequence 1.mov

公开 Deposited

可下载的内容

下载视频
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/c821gp765

Descriptions

Attribute NameValues
Creator
Abstract
  • The importance of wood bonding increased in the last decades due to the increased usage of wood composites whose performance depends to a large extent on the adhesive penetration and subsequent bonding of the adherends. The presented research used XMT (x-ray microtomography) to perform a non-destructive, threedimensional analysis of the adhesive bondline and wood-structure of Southern yellow pine, Douglas-fir and yellow-poplar samples. A phenol-formaldehyde adhesive was used. The sodium hydroxide catalyst was replaced with rubidium hydroxide during resin formulation. This was done to improve the image contrast. The reconstructions of the wood structure of Southern yellow pine showed tracheids, rays, fusiform rays, resin canals and pits. On the Douglas-fir sample tracheids, pits and rays were displayed clearly. The yellow-poplar images showed vessels, fibers, bordered pits, scalariform sieve plates and rays. The renderings of the adhesive-bondline of Southern yellow pine proved the dominant role of tracheids for the adhesive flow and showed rays as a secondary pathway of adhesive flow. The results revealed no adhesive flow occured through bordered pits, while simple pits permitted some adhesive flow through ray parenchyma. The results for Douglas-fir showed a similar result; the tracheids were the predominant path of adhesive penetration, while rays played a secondary role and no adhesive flow through the pit aperture was visible. The adhesive flow through the microstructure of yellow-poplar wood occured mainly through vessels and also through rays, but no adhesive flow through the pits was directly observed. The segmentation of the images in three phases: void space, cell wall substance and adhesive, enabled the calculation of the effective bondline thickness based on the adhesive, as well as the volumetric measurement of all three elements and their share on the sample volume. Subsequent experiments showed that the exposure of the Southern yellow pine and yellow-poplar bondlines to cyclic moisture did not cause delaminations or cracks. However, there were some indicators that the samples experienced some irreversible swelling. Finally, the generation of 3-D animations of wood samples and bondlines of Southern yellow pine, Douglas-fir and yellow poplar was achieved. This animation was a way to present the results of this research in a quick and accessible way that illustrates the three-dimensional microstructure of a wood-adhesive bond.
关键词
权利声明

关联

Parents:

单件

缩略图 标题 上传日期 公开度 行动
file details Sequence_1.mov 2017-10-20 公开 下载