TECHNOLOGY FOCUS - POLYMERS - Preparation: No preparation method is given. Preferred Components: The ethylene oxide copolymer having heat of crystallization is not greater than 60 mJ/mg. Preferred Process: The ethylene oxide copolymer obtained by polymerizing a monomer composition containing comonomer ( not less than 10 mol.%). The ethylene oxide copolymer is a random copolymer whose weight-average molecular weight is not less than 20000 to not greater than 500000. EXAMPLE - Toluene (286.5 parts) was dehydrated with the molecular sieve, and t-butoxy potassium (0.54 parts)(tetrahydrofuran (THF) (20 wt.%) solution) as an initiating reagent were sequentially added to the reactor vessel. Then, the headspace of the reactor vessel was replaced with nitrogen. Pressure was applied with nitrogen until pressure in the reactor became 0.3 MPa, and its temperature was increased. The temperature in the reactor vessel was 90 degrees C, ethylene oxide and a monomer composition made of butylene oxide dehydrated with the molecular sieve; and allyl glycidyl ether oxide dehydrated with the molecular sieve were supplied for 2.5 hours at quantitatively constant rates respectively of 47 parts per hour and 10.3 parts per hour, and were then further supplied for 5 hours at quantitatively constant rates respectively of 23.5 parts per hour and 5.15 parts per hour. During the supply, reaction was performed at 100 degrees C while increase in pressure and temperature inside the reactor vessel caused by heat of polymerization was monitored and controlled. After the supply, a blended content in the reactor vessel was left to stand for 5 hours to obtained ethylene oxide copolymer (test). The comparative copolymer prepared similar to test but ethylene oxide and a monomer composition of butylene oxide and allyl glycidyl ether were supplied for 2.5 hours at quantitatively constant rates respectively of 51 parts per hour and 6.3 parts per hour, and were then further supplied for 5 hours at quantitatively constant rates respectively of 25.5 parts per hour and 3.15 parts per hour. The both copolymer subjected to detection of glass transition temperature. The test/comparative showed glass transition temperature of -65.9 degrees C/-62.1 degrees C.