Complex sentence: Elsie had a fictional, cartoon mate, Elmer the Bull, who was created in 1940 and lent to Borden's then chemical-division as the mascot for Elmer's Glue.
Split into simpler sentences: Elsie had a fictional, cartoon mate, Elmer the Bull. Created in 1940 and lent to Borden's then chemical-division as mascot for Elmer's Glue.