Make strong and CLEAR composite materials with natural wood! Get all the strength of wood without all that darn opacity getting in your way! I figured out a quick and simple recipe with some cheap ingredients you can do right at home! Build wooden windows, or clear, wood cell-phone cases!
This video gives a quick overview of the whole thing, and shows some examples of the material in motion!
This is based off the paper by Zhu et al, called "Highly Anisotropic, Highly Transparent Wood Composites" http://onlinelibrary.wiley.com.sci-hub.cc/doi/10.1...
The basic idea is that wood can be thought of as two parts:
Cellulose: Strong structural strings which are naturally clear
Lignin: a sort of opaque glue that holds all those strong cellulose fibers together
If you can strip away the opaque (and non-structural) parts of the wood (the lignin) and replace it with clear epoxy, then you will have all the strength of the Cellulose fibers, but also be able to see through it!
In this way, you are making a composite material, much like fiberglass! One of the extra cool things about this, though, is that you are able to retain the existing structures formed by the way the wood grew, to theoretically make it extra strong and lightweight!
I saw lots of articles discussing this clever idea when this scientific paper first came out, and I wanted to see how do-able it would be as a simple process people can do at home. Turns out even with my basic, modified recipe, you can get some great results!
It's a pretty simple recipe that would be a fun experiment to do with kids to share ideas about chemicals and materials properties of wood. It can also as part of a design process
Note: This involves using some caustic chemicals. This is a first for me, so it was a bit out of my comfort zone, but I came through unscathed, and you can too! just use safety glasses and gloves!
The official recipe in the calls for about 8% H2O2, which you can make from 35% H2O2
available here: https://www.amazon.com/Hydrogen-Peroxide-Filled-Dr...
or I just used a whole bottle of regular cheap 3% H2O2 that you can get at the grocery store! It didn't bleach it that much, but it got it pretty transparent.
Aeromarine 300/21 -The official type they used in the paper: https://www.amazon.com/AeroMarine-300-Epoxy-Resin-... ($63)
Smooth-on (similar kind) (20$) https://www.amazon.com/Smooth--Smooth-Cast-Liquid-...
Table-top (kinda flexible) ($43) https://www.amazon.com/gp/product/B00V2GKMWW/ref=o...
This recipe is a modified basic version of comes from a paper by Zhu et al-
Highly Anisotropic, Highly Transparent Wood Composites
Mingwei Zhu, Jianwei Song, Tian Li, Amy Gong, Yanbin Wang, Jiaqi Dai, Yonggang Yao, Wei Luo, Doug Henderson, and Liangbing Hu*
http://onlinelibrary.wiley.com/doi/10.1002/adma.20... or Sci-Hub to get more Open Access: http://onlinelibrary.wiley.com.sci-hub.cc/doi/10.1...
From their paper, here is their full recipe-
"Materials and Chemicals: Basswood from Walnut Hollow Company
was used in this study. The chemicals used in removing lignin contents
from wood were sodium hydroxide (>98%, Sigma-Aldrich), sodium sulphite (>98%, Sigma-Aldrich), and hydrogen peroxide (30% solution, EMD Millipore Corporation). The polymer used for infiltration was
epoxy resin (#300 resin and #21 nonblushing cycloaliphatic hardener,
AeroMarine Products, Inc.). The solvents used were ethanol alcohol
(190 proof, Pharmco-Aaper) and deionized (DI) water.
Lignin Removal from Wood: The lignin removal solution was prepared
by dissolving NaOH (2.5 mol L−1
The wood slices were immersed in the lignin removal solution and kept
boiling for 12 h, followed by rinsing in hot distilled water three times to
remove most of the chemicals. The wood blocks were then placed in
the bleaching solution (H2O2, 2.5 mol L−1
without stirring. When the yellow color of the sample disappeared, the
samples were removed and rinsed with cold water. The lignin-removed
samples were preserved in ethanol.
Polymer Infiltration: Epoxy resin was prepared by mixing the two liquid
components (#300 resin and #21 nonblushing cycloaliphatic hardener)
at a ratio of 2 to 1. Then the lignin-removed wood was placed at the
bottom of a dish and immersed in the liquid resin. The solution was
then degased under 200 Pa to remove the gas and ethanol solvent in
wood. Approximately 5 min later, the vacuum was released to let the
resin filling into wood structure by atmosphere pressure. The process
was repeated for three times. All the above processes were finished
within 30 min to avoid the polymer solidification. Finally, the dish
containing the wood sample and resin was kept static at 30 °C for 12 h.
The resin-infiltrated wood sample was peeled off from the dish after the
resin was completely solidified.
) and Na2SO3 (0.4 mol L−1)"