EFFECT OF CHEMISTRY ON THERMO-MECHANICAL SHAPE-MEMORY PROPERTIES OF ACRYLATE NETWORKS
Shape-memory acrylate networks are novel materials for both biomedical and industrialapplications.The purpose of this study is to understand how the chemical structure dictatesthermo-mechanical properties of shape-memory acrylate networks,specifically strain tofailure and toughness.The strain to failure is useful because it is pivotal to know how muchrecovery strain the material experiences.To understand how the structure is related tomechanical properties,such as strain to failure,materials of differing chain stiffness ratio,C∞,are compared at varying percentages of cross-linker.First,a set of networks ischaracterized to understand the trends in the basic thermo-mechanical properties of themonomers once cross-linked.Thirty-one acrylates are separated into two groups: linearchain builders and cross-linkers.The networks are systematically synthesized by varyingthe linear chain builders with poly(ethylene glycol) dimethacrylate Mn～550 (PEGDMA550)as the cross-linker,and varying the cross-linker while holding tert-butyl acrylate constant asthe linear chain builder.A dynamic mechanical analyzer evaluates the glass transitiontemperature and rubbery modulus.Subsequently,strain to failure tests are performed at theglass transition temperature of each respective mixture.The linear chain builders withPEGDMA550 have glass transition temperatures ranging from -29 to 112 ℃,and rubberymoduli from 2.75 to 17.5 MPa.The cross-linkers co-polymerized with tert-butyl acrylatehave glass transition temperatures ranging from -3 to 98 ℃,and rubbery moduli from 6 to130 MPa.Materials can be selected to independently vary the glass transition temperatureand rubbery modulus.Based upon the initial screening results,networks with different C∞are formed at varying percentages of cross-linker.C∞ values typically apply only for purelinear chain builders,not networks,and here we demonstrate how chemical cross-linkingalters the impact of C∞ on strain to failure.The comparison of these networks yields insightinto the relationship between chemical structure and mechanical properties leading to arelationship between C∞,percentage cross-linker,and strain to failure.
David Safranski Ken Gall
School of Materials Science and Engineering,Georgia Institute of Technology,Atlanta,GA,USA School of Materials Science and Engineering,Georgia Institute of Technology,Atlanta,GA,USA Woodruff
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
637
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）