Summary Infrared methods have been used in determining 1, 2-and trans-l, 4addition in polybutadiene polytnerized in the temperature range-19 to 97" and butadiene-styrene copolymers prepared at-18, 5 and 50". trans-lj4-Addition increases and 1, 2-addition decreases with decreasing temperature of polymerization. At-19") substantially all of the 1, 4- addition product is present in the trans-1, I-form. Approximately 20Vc 1," addition oc-curs ...