Polyurethane vs. Polypropylene

[zacMX5aus]

Hi all,

I am looking at buying an r package style front lip for me NA. I have found two that are reasonably priced, the only difference being one is polypropylene and one is polyurethane. I don't know much about plastics and was hoping someone could give some advice on if there is really much difference between PU and PP, is one more likely to crack/damage? is one easier to paint than the other? any other info.

Your help is greatly appreciated.

-Zac

[manga_blue]

I'd just go with style and price.

I have a high density polyethylene (HDPE) fishing kayak that I've used for years in what you might call high-risk locations (i.e. places where boats don't dare go). It's been crunched onto exposed bomboras, speared nose first into a rocky bottom, piched end over end in heavy swell, slammed against cliffs, rolled over sandy bars and dragged across oyster beds. Apart from oyster scratches there's hardly a mark on it. If HDPE survives all that it will stand up fine to use as a body kit.

In terms of toughness LPDE (low density PE) is weaker than HDPE which is weaker than polypropylene. HDPE and polypropylene should work fine. LPDE is more flexible and would probably be OK too..

In terms of painting they're all about equally difficult. All need special primers.

[StillIC]

Polyurethane (PU) is a more expensive and more robust plastic than polyprop (PP). PU is used in traffic cones, rally car mudflaps and the like...very tough. PP is used in cheap outdoor furniture, corflute signs and the like, but is still pretty good, toughness wise, considering its price. Having said all that, my guess is the PP lip will be lighter than the PU.

[93_Clubman]

r package style front lip for me NA.

Location of body part, as you seemed to be indicating (in this case a front lip) is another consideration if ground clearance in minimal due to potential contact with speed humps & kerbing when parking etc.

[hks_kansei]

For a front lip I'd be wanting whichever has the most ability to bend rather than break.

[Mr Morlock]

I reckon whatever you put on the front of an MX-5 i.e. a lip if it's below standard height its a pain. I have a modern car with a low lip - standard product but its low and it carries scratches. Too many high kerbs, traffic bumps , and dodgy driveways.