title: Fracture energy of polymer gels with controlled network structures.
abstract: We have investigated the fracture behaviors of tetra-arm polyethylene glycol (Tetra-PEG) gels with controlled network structures. Tetra-PEG gels were prepared by AB-type crosslink-coupling of mutually reactive tetra-arm prepolymers with different concentrations and molecular weights. This series of controlled network structures, for the first time, enabled us to quantitatively examine the Lake-Thomas model, which is the most popular model predicting fracture energies of elastomers. The experimental data showed good agreement with the Lake-Thomas model, and indicated a new molecular interpretation for the displacement length (L), the area around a crack tip within which the network strands are fully stretched. L corresponded to the three times of end-to-end distance of network strands, regardless of all parameters examined. We conclude that the Lake-Thomas model can quantitatively predict the fracture energy of polymer network without trapped entanglements, with the enhancement factor being near 3.
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Akagi
authors.forename: Hayato
authors.initials: H
authors.lastname: Sakurai
authors.forename: Jian Ping
authors.initials: JP
authors.lastname: Gong
authors.forename: Ung-il
authors.initials: UI
authors.lastname: Chung
authors.forename: Takamasa
authors.initials: T
authors.lastname: Sakai
mesh_terms: D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry; D008422:Materials Testing; D015394:Molecular Structure; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D005782:Gels; D011092:Polyethylene Glycols