btw, have you seen this:

"

But natural substances have their drawbacks that the researchers had to come to terms with in the project. In the case of jute fibers, it was the high affinity to water and the polar fiber surface. Both of these factors hinder the optimal binding of the fiber to the duromer matrix. The difficulty: As a natural raw material, the jute fiber draws water from the air even after harvesting. The researchers have solved this problem by drying in an oven at 80 degrees Celsius. " However, the fibers had to be processed immediately, because as soon as they are exposed to the ambient air again, they draw water once more. So the time window was very short," reports Hüttl.

The polarity of the surface results from organic residues found on the natural raw material. Hüttl reports that a method developed by the Indian partners came to the rescue here. "The organic residues were removed with hydrogen peroxide, i.e. by chemical bleaching. Afterwards, the adhesion was measurably better."

Yes, I am familiar with the described problem. I try to keep the low humidity when storing PLA and fibers as well as drying the cloth before lamination as proposed. I have not looked into chemically treating the fibers yet.

I will try to perform some comparable strength tests in the following weeks. Pure PLA vs new flax composite...

Looking forward to it, thanks - keep us informed

Hi Mitja, 

I've seen your strength (comparison) test and found it most interesting as you did. It then showed a poor improvement in strength based on several issues, that you tried to solve thereafter. 

How about conducting a similar test to compare with the previous material to show the results of your new findings? 

As you are using the new material in your new drone as structural component, I am not so much interested in the impact resistance but in the (reinforcing) strength of that composite...

Hi Pascal,

thank you for your interest.

I performed a (non-standardized) strength test in the previous project log (https://hackaday.io/project/171199-bio-degradable-pla-jute-composite-drone) that showed that strength was marginally improved compared to PLA. I have to repeat the tests with the new composite which has a much higer fiber/PLA ratio as well as better fiber to PLA adhesion. If you have a proposal or a way to test the strength of such thin sheets please contact me.

From the experience, the impact resistance should be significantly improved by adding the fibers (similar to other fiber based composites). I have not made a standardized test for it either, but I think strength(/weight) and impact resistance would be interesting to test.

Thickness of the material is approx 0,8mm and currently sheets of max. 200x200mm can be made. I could make larger sheets by getting a 3D printer with larger xy build area and laminator (oven, iron, etc).

Hey Mitja, 

your experimental approach is really amazing. Looking for solution of bringing sustainable ideas for drone builders in Africa, I think your findings lead in a good way. Have you done any more strength/comparison tests on the improved material? 

The intention of this question is to get a feeling of  what maximum weight would be achievable for your drone ?  

What's the size and thickness of sheets that can easily be fabricated in such a "simple" manner?

Best, Pascal

Hi Pascal,

thank you for your interest.

I performed a (non-standardized) strength test in the previous project log (https://hackaday.io/project/171199-bio-degradable-pla-jute-composite-drone) that showed that strength was marginally improved compared to PLA. I have to repeat the tests with the new composite which has a much higer fiber/PLA ratio as well as better fiber to PLA adhesion. If you have a proposal or a way to test the strength of such thin sheets please contact me.

From the experience, the impact resistance should be significantly improved by adding the fibers (similar to other fiber based composites). I have not made a standardized test for it either, but I think strength(/weight) and impact resistance would be interesting to test.

Thickness of the material is approx 0,8mm and currently sheets of max. 200x200mm can be made. I could make larger sheets by getting a 3D printer with larger xy build area and laminator (oven, iron, etc).