Polyester resins are thermosetting; "thermosetting" means the plastic softens when initially heated, but sets permanently rigid once it has cooled (as opposed to "thermoplastics", which re-soften with heat). Polyester resin is often purchased in liquid form for the production of glass-reinforced plastic. In this case, a catalyst (typically methyl ethyl ketone peroxidebenzoyl peroxide is a somewhat less hazardous alternative suitable for some purposes.(MEKP) (also known as butanone peroxide) is used to initiate the polymerization reaction;
In general all the resins you refer to in your article are of the thermosetting type, ie they cure by heat or catalyst, once this process has taken place it cannot be reversed.
Thermoplastics OTH can be re-melted after processing.