title: Properties of epsilon-caprolactone/DL-lactide (epsilon-CL/DL-LA) copolymers with a minor epsilon-CL content.
abstract: In this study the properties of DL-lactide (DL-LA) copolymers with 5, 10, 15, 20, and 30 wt % (in feed) of epsilon-caprolactone (epsilon-CL) polymerized with stannous(II)octoate (SnOct) as catalyst and glycerol, laurylalcohol, or pentaerythritol as initiator were investigated. Thermal studies showed that the addition of 5 wt % (in feed) of epsilon-CL to the P(CL/DL-LA) copolymer decreased the Tg by about 5 degrees C. Hydrolysis tests were carried out for copolymers with 20 and 30 wt % (in feed) of epsilon-CL to study the degradation rate. Molecular weights decreased dramatically during the first week of hydrolysis, with mass losses occuring a few weeks later. The influence of glycerol and pentaerythritol as initiators, and the influence of epsilon-CL content on stress-strain behavior, tension set, and rheologic properties of the P(CL/DL-LA) copolymers were also investigated. The tensile testing of P(CL/DL-LA) copolymers containing 5, 10, 15, 20 wt % (in feed) of epsilon-CL showed that the properties of copolymers varied from hard and brittle to rubbery. The permanence of elastic properties was investigated with tension set measurements. These studies showed that copolymers crept remarkably under stress. The viscosity and elasticity of P(CL/DL-LA) copolymers at 120 degrees C were investigated using rheology studies.
authors.affiliation: Department of Chemical Engineering, Helsinki University of Technology, Finland.
authors.forename: M P
authors.initials: MP
authors.lastname: Hiljanen-Vainio
authors.forename: P A
authors.initials: PA
authors.lastname: Orava
authors.forename: J V
authors.initials: JV
authors.lastname: Seppälä
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004548:Elasticity; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry*; D012212:Rheology; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; C062968:lactide-caprolactone copolymer