Temperature and Strength

• Nylon is able to withstand temperatures up to 450 F while polypropylene is able to withstand up to 320 F. Nylon has a strength rating of "high" and polypropylene has a strength rating of "medium."
  
  

Resistance to the Environment

• Both nylon and polypropylene are rated "good" with respect to ultraviolet resistance. Both materials received a rating of "excellent" for resistance to mildew. For resistance to acids and alkalis, nylon received ratings of "poor" and "good," respectively, while polypropylene received two ratings of "excellent."
  
  

Stretch and Other Comparisons

• Nylon will expand a little when wet and will stretch approximately 25% of the rated breaking strength, while polypropylene will stretch approximately 30%. Nylon is very resistant to abrasion while polypropylene is rated as "fair." One issue found with nylon is that it absorbs water and doesn't float, which is a problem in the marine environment. Nylon has a longer life than polypropylene and is machine washable. Polypropylene does float in water and is less expensive than nylon.