Part numbers definitely.

I have seen the V shaped reinforcing  design on landing flaps – The Bucker Bestmann for example – but it was a lot smaller than this.

P&P I dit a lot of natural rubber processing as a student and cutting lumps of natural rubber and then mixed with sulphur and other ingredients on a two roll mill then cured sheets for tear , resiliency and tensile testing  – so your vulcanite test sounds good. 

Polypropylene has a methyl side group that can be distributed either side of the chain – so when it is synthesized it can be produced as random, alternating or all on one side – which affects its crystallization and physical properties.  The tech terms are  atactic, syndiotactic and isotactic. Large use in ropes as it is very aliphatic and doesn’t get affected by water.

P&P I think that you need to think about these not as generic “plastics” with tradenames but as the individual polymer chains and how they react.

Nylon is a tradename for a family of polyamides- the most frequent being Nylon 6,6 or polyhexamethyleneadipamide. It is a thermoplastic with no cross linking. It is highly aliphatic from the 6 long carbon chains between each of the CO NH  linkages.

Bakelite is a phenyl formaldehyde resin is a thermoset ( heavily cross linked ) and not a thermoplastic.

Neoprene is a generic term for polychloroprene. It is neither a thermoset or a thermoplastic it is an elastomer with limited crosslinking between the polymer chains meaning that the chains are returned to the initial position when force is applied and removed It also has lower crystallisation than the resin and thermoplastics.  

All three materials mentioned behave very differently in use and in stability to light, water and oxygen.

Wind turbine blades are composites of glass or carbon fibre impregnated with a resin.