I'm confused by terms GRP, 'fiberglass', 'resin', etc

[Squidly-Diddly]

is the resin the 'plastic' in GlassReenforcedPlastic?

Is it epoxy(with hardener) or normally something else(with hardener)?

Is GRP something new or just the term for 'fiberglass''; as in "the boat has a fiberglass hull"?

Is the 'plastic' in GRP able to be softened, worked such as in rotomolded fiberglass kayaks?

Can fiberglass(the cloth) be used in a rotomolded design such as a plastic kayak?

Where is a good site that gives the strengths and weaknesses and general properties(as their ease of use as well as actual structures)?

[charmc]

FRP and GRP are variations on the same thing, and diferent resins can be used. There is a good introductory discussion here:

http://www.duroplastic.com/art_bbfg.html

Rotomolding uses different plastics entirely. Here is a discussion of the differences between FRP/GRP construction and rotomolded plastic construction in kayaks :

http://www.useakayak.org/equipment/b...nstuction.html

[PAR]

GRP is Glass Reinforced Plastic, FRP is Fiber Reinforced Plastic. Both terms are now interchangeable in the industry.

Resin is the material you add either a catalyst or an activator to, which starts the chemical reaction and the cure process. There are a number of different resins available, all having different physical properties when cured and needing different handling procedures.

Generally the polyester and vinylester resins will require a catalyst, while the epoxies need an activator. The differences between the different chemical combinations can get pretty complicated, so I'll leave it at that. Simply put, both activators and catalists are hardners, though they work differently in the chemical process of the cure.

Weakest on the usual suspect list are the polyester resins, followed by vinylester resin, with epoxy being the strongest and most waterproof.

I don't think these resins and reinforcement fabrics would do well in a rotary tooling type of manufacture process. Keeping the fabrics in the place you need them, would prove problematic in a rotating mold. These Roto molded pieces use a different type of plastic, generally beads or powder which spread to every corner of the mold (during rotation) while being heated to "weld" (literally) the individual plastic bits together into one homogenous whole.

It would take a considerable understanding, of the chemistry (not to mention the engineering) involved to tool up for a new approach in one off or production manufacturing of this type, be it boat shapes or other wise.