Wood Adhesives and Coatings. Lecture 1 Winter Term

Transcription

1 Wood Adhesives and Coatings Lecture 1 Winter Term

2 Who s teaching it and why I am teaching it Scott Renneckar Associate Professor in the department of wood science wood scientist/applied chemist background (Cal and VT) PhD research in wood-plastic composites and taught wood composites/adhesives and wood material science courses for a decade. other job- runs research program related to converting biomass into advanced materials-films, fibers & foams For the love of all things that relate to polymers, nanotechnology, and sustainability

3 What this course is about Wood chemistry and polymer science topics The molecular aspects of wood and compounds related to adhesion and durability (coatings and preservatives) Wood surfaces Adhesion from the molecular level of why and how things stick together

4 Why these topics are important Many wood products are composites your degree is in wood products and processing. You will need to understand the behavior of these materials in your career Lumber, panels, and paper are only the tip of the iceberg to how we can manipulate wood into new materials. Knowing the molecular structure allows the conversion into things like carbon fibre, cellulose nanocrystals, and bone scaffolds. Many wood products have protective coatings and finishes, how do they work?

5 utline Focusing at the molecular level The fuzzy composition of wood Composite systems Wood is remarkable

6 Perspectives We are not acquainted with anything on the order of 10-9

7 Boundaries: Solid-gas interface of a silver spoon Silver spoon and silver atoms mlpforums.com nanotechweb.org

8 Boundaries: Solid-gas interface of plastic spoon Plastic spoon and macromolecules

9 Boundaries: Solid-gas interface of wood?

10 Towards the molecular level of wood US Forest Products Laboratory Image (USDA)

11 Boundaries: Down to the microscale SEM image from Nanotructural assembly of cellulose, hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid. by N. Terashima and co-workers, in J wood Sci (2009) 55:

12 Cell wall structure of woody plants Singh et al. High variability in the thickness of the S3 layer in pinus radiate tracheids. Holzforschung, :

13 Blend of polymers at the submicroscale Rowell et al. Cell Wall Chemistry 2005

14 Suggested organization of cell wall at the nanoscale This schematic is from an article Micromechanical Understanding of the cellwall structure by Lennart Salmén in C.R. Biologies 327 (2004) Schematic from Nanotructural assembly of cellulose, hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid. by N. Terashima and co-workers, in J wood Sci (2009) 55:

15 Reinforced concrete model en.wikipedia.org/wiki/reinforced_concrete

16 ther familiar composites: Carbon fiber reinforced polymer composites

17 This schematic provides insight into what a native surface would be like vs. a cut surface H Cellulose H H H H H Xylan backbone H H H H H H H H H 2 C H C C C C H H H Mannose H C H H H H 3 C H Schematic from Nanotructural assembly of cellulose, hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid. by N. Terashima and co-workers, in J wood Sci (2009) 55: H 3 C CH 3 Some representation of lignin

18 Imaging of the cell wall with atomic force microscopy (AFM) shows complex layers Fahlen and Salmen Biomacromolecules SEM image from Nanotructural assembly of cellulose, hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid. by N. Terashima and co-workers, in J wood Sci (2009) 55:

19 Imaging of the cell wall: Electron Microscopy Terashima et al. C.R. Biologies 327 (2004)

20 Wood is Truly Remarkable: Made from air! Trees are made into a solid materials/structures in an environment that consists of small molecules: C 2, N 2, H 2 0, CH 4