Wood Physics & Wood Materials

Purpose: investigate cell wall polymers with high spatial resolution, while retaining the structure

Sample requirements: for surface scans the surface has to be as flat as possible (microtome cuts or polishing)

Spectral imaging: for every pixel a spectrum covering the entire wave number range is obtained

Fast imaging: intensity only at one specific wave number

Applications:

Visualization of the wood composition (cellulose and lignin)

Information about the orientation of the cellulose microfibrils

Visualization of the chemical modification area

in \(\left[ kg/m^3 \right]\)

spruce
470

douglas fir
530

larch
500 - 560

pine
350 - 850

maple
620 - 750

oak
600 -900

birch (european)
670

ash (european)
710

beech
700 - 900

ebony
1100 - 1300

balsa
110 - 140

\(E_T < E_R << E_L\)

softwood:

1 : 1.7 : 20

hardwood

1 : 1.7 : 13

Impact factors

• moisture content
• microfibril angle

in \(\left[ N/mm^2 \right]\)

\(E_L -- E_T -- E_R\)

Spruce
10'000 -- 450 -- 800

Pine
11'000 -- 500 -- 1000

Oak
13'000 -- 920 -- 1580

Azobe/Bongossi
17'000 -- 2060 -- 3230

in \(\left[ N/mm^2 \right]\)

\(G_{LR} -- G_{RT} -- G_{IT}\)

Spruce
600 -- 40 -- 650

Pine
- -- 70 -- 680

Oak
1080 -- 400 -- 800

\(\begin{bmatrix}\varepsilon_1 \\ \varepsilon_2 \\ \varepsilon_3 \\\gamma_{23} \\ \gamma_{13} \\ \gamma_{12} \\\end{bmatrix}=\begin{bmatrix}\frac{1}{E_1} & -\frac{\mu_{21}}{E_2} & -\frac{\mu_{31}}{E_3} & 0 & 0 & 0 \\-\frac{\mu_{12}}{E_1} & \frac{1}{E_2} & -\frac{\mu_{32}}{E_3} & 0 & 0 & 0 \\-\frac{\mu_{13}}{E_1} & -\frac{\mu_{23}}{E_2} & \frac{1}{E_3} & 0 & 0 & 0 \\0 & 0 & 0 & \frac{1}{G_{23}} & 0 & 0 \\0 & 0 & 0 & 0 & \frac{1}{G_{13}} & 0 \\0 & 0 & 0 & 0 & 0 & \frac{1}{G_{12}} \\\end{bmatrix}\cdot\begin{bmatrix}\sigma_1 \\ \sigma_2 \\ \sigma_3 \\\tau_{23} \\ \tau_{13} \\ \tau_{12} \\\end{bmatrix}\)

3 E-Moduli

3 Shear Moduli

6 Poisson's ratios