Generally speaking engineering plastics are those which are now replacing conventional materials such as metals and alloys in general engineering, or, they are materials which have properties which are not available in conventional materials.
A work range of plastics are now being used in engineering. These include polyolefins and their copolymers, polyacetals , polyphenylene oxide, polyarylates, epoxy resins, polyetheretherketone, polyetherimide, polyetherester amide, polyamides, polyamide-imide, polyimides, polydiallylisophalate, polyallyl phthalate, polyethyleneterephthalate, polybutylene terephthalrte, polycarbonate, polyesters, polyethylene sulphide, polyphenylene sulphide, aromatic disulphides, fluorinated ethylene-propylene, polytetrafluoro ethylene, polyvinyl fluoride, polyvinylidene fluoride, perfluoroalkoxy ethylene, ethylene-tetrafluoroethylene, ethylene chlorotrifluoroethylene and polysiloxanes.
Some mechanical properties of engineering polymers can be considerably improved by the incorporation in their formulation of reinforcing agents such as glass fiber, talc, carbon fiber, carbon nanotubes, organically modified clays and mica.
The data you have given for the unreinforced epoxy resins is totally inaccurate! The tensile strength of a typical epoxy resin is ~60-80MPa - not the 600 that you have given. The unreinforced flexural modulus is typically 3-3.5GPa, not the 80 that you have given. Thus glass fibre does increase both these properties drastically as it does the properties of other resins. Your data on elongation to break of epoxies of 13% is also suspect - very high in my opinion. Perhaps I can help. For good epoxies with a Tg of 80-100°C, elongation between 5 & 8% is normal. Resins with increasingTg have decreasing elongation to break, normally due to higher Xlink density. So a 120°C Tg resin would have 4-5% elongation to break.
Your data for the polyimide in the first table is also questionable as it is identical to the epoxy resin data. Is the data in the 1st table for "polyester" resin meant to be for unsaturated polyester resin? If so it is also incorrect. Flexural modulus does not go much higher than 3.5GPa. Your article is interesting. I gave it 1 star as you have given very inaccurate and incomplete facts about the epoxies and other resins. For the reinforced data, I cannot comment as you have not said in what form the glass fibre is - UD, fabric, non woven...