Binder in Carbon Tow?

[BenCarbonNovice]

Does anyone know, how are the individual fibers within a carbon tow held together.  It seems that there is some sort of binder.

Out of curiosity, I dipped a 2 inch scrap tow into some acetone, and was quite amazed.  It went totally limp.  Like dry spaghetti vs cooked spaghetti.   So then i took a small scrap of 2x2 3K.  As we all know, that stuf is super springy.  I dipped it in the acetone, folded it in a complex curve and let it dry.  I'm amazed. For the most part it is holding its new shape, but is once again springy.

It almost seems like there is something applied to the tow strands, to keep them together.  The acetone appears to dissolve it partly, but then there is enough left over to regain some binding properties once the acetone has evaporated.

If you have actual knowledge to this, can you please cite your sources?  I have scoured the internet, and found nothing.

Ben

[Shane_Sorbom]

Hi Ben!

The binder is called "sizing"! It is applied to the raw carbon fibers after they come out of the furnace, before they are wound onto the spools. The sizing can be thought of as a primer, as well as an added help in keeping the individual tows together on the spool. The sizing is typically proprietary to the manufacturer, but a little digging through the Technical Data Sheet will tell you about the compatibility with the resin you choose.

Sizings – Why Do They Matter - Composite Envisions

Sizing Up Fiber Sizings | CompositesWorld

 

Great question!

 

Thanks,

Shane Sorbom