Chopped mat weaknes is matter of context Posted by: scott_f on Dec-17-12 4:30 PM (EST)
The chopped mat I have seen is layered with woven cloth. This makes for a strong layup as chopped mat is isotropic and helps to re-enforce the weakness of bi-directional woven cloth. I have not seen cloth layers laid down at 45 degree angles to help strengthen a cloth only layup (although that layer may be hidden underneath the visible layers). Cloth is strong, but only in two directions. Pull at cloth on a 45 or even 20 degree angle and it is significantly weaker. Mat also bonds very well to other layers because its random surface strands interlace. I have also heard that chopped mat is more resistant to tearing after a puncture, but that is hearsay.