What is the group of chemical substances with the lowest ultimate tensile strength whose topic's main category is Category:Nylon ?
select ?ent where { ?ent wdt:P31 wd:Q17339814 . ?ent wdt:P5479 ?obj . ?ent wdt:P910 wd:Q55272807} ORDER BY ASC(?obj)LIMIT 5 
group or class of chemical substances: Q17339814 category:nylon: Q55272807