What type of plastic is used to make toy trains?

Don U.

You were doing fine until you got to "Football Helmets." Materials used for the production of football helmets have evolved from leather, to harder leather, to molded polycarbonate shells.

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The following indicates relative impact strength of ABS vs Polycarbonate. 

Izod Impact Test (notched)
ABS  7.7 ft-lbs/in of notch
POLYCARBONATE 12.0-16.0 ft-lbs/in of notch

The Izod test is a precision way to whack things with a hammer.

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Steam and water pipes you mention are polyethylene.

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