The old name of Kevlar is Poly(para-phenylene terephthalamide). When mechanical drawing is done to it, the polymeric chains are oriented to largely planar sheet-like structures & this causes the inter-yarn slippage besides the existing inter-chain secondary bonds between the neighboring macro molecules. The 2o bonds are nicely arranged in a way that will hinder adhesion with other substrates.

My humble suggestion is to try Nomex which is called Poly(meta-phenylene isophthalamide). Structure of this aramide may impart better characteristics than the other aramide with regard to what you are looking for.

You need to use a crosslinker to check interchain slippage and an interfacial adhesive for better adhesion of the polymer with the kevlar reinforced composite.

Interesting