I'm happy using EC resin (its great) but I'm a chemist so I'm curious about resin structures and properties.  For example, does anyone know what different properties the different bis-phenols give a resin?  I'm also interested in what properties you get from different hardeners and what effect different polymer numbers have on the resins?  Links to any info would be awesome.

Thanks guys.

I'm assuming you're talking about epoxies since you mentioned bisphenols. Most epoxies used in composites are bisphenol-A based and AFAIK, the big differences amongst them is in the hardeners, which are amines most of the time. Unique qualities are IP, wouldn't know who would reveal that info

Mostly interested in epoxies yeah, but I would be interested in anything TBH.  I'm a chemist so I was looking for a little academic stimulation.  It seems like the larger polymer numbered resins have better mechanical properties but then are mega viscous. 

A complete swerve ball but do you know if anyone has produced an epoxy thread?  It'd be interesting if this could be incorperated into the cloth and crosslinked on lay-up.  It'd need some short chain resin to fill in but could work well. 

I'm also interested in any alternative new tech.  I have vague memories of a thermoplastic thread interwoven that melted on bake.  Resin free system!  I think Carr made that one.

Havent heard of threaded epoxy, but theres a material called Twintex, which is PP interwoven with glass. Very impact resistant, very cheap. Its probably the material you think Carr made. Its a fairly thick fabric.

Prepregs do just what youre asking for though.

Yes, as a general rule of thumb, the mechanical properties of epoxies are proportional to their viscosity. The more watery the resin, the weaker it is. For example I managed to source an Epoxy with a Tg of 320C, but its so viscous, its considered a Stage B material, which means it has the viscosity of an resin  that has gelled.