Assertion: natural polymer | /r/HasProperty | modified in 19th century
Facets:
value: to form vulcanized rubber
type: PURPOSE
value: chemically
type: MANNER
value: to form celluloid
type: PURPOSE
Source sentences:
text: Natural polymers, such as cellulose and latex, were first chemically modified in the 19th century to form celluloid and vulcanized rubber.