1. Polymer Engineering Center, Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706-1691, USA
2. Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA
3. Department of Mechanical Engineering, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681-9000, USA
4. Department of Engineering Science and Materials, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681-9000, USA