caa a22 4500 475782380 CHVBK 20180406123648.0 cr unu---uuuuu 170329e20000601xx s 000 0 eng 10.1023/A:1008977806693 doi (NATIONALLICENCE)springer-10.1023/A:1008977806693 Processing and properties of two different poly (ortho esters) [Elektronische Daten] [M. Kellomäki, J. Heller, P. Törmälä] Processing and properties of two structurally different poly (ortho esters) (POE) and their in vitro behavior have been compared. One POE was a copolymer of diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, trans-cyclohexanedimethanol and polyacetal. The other POE was a copolymer of diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, trans-cyclohexanedimethanol and trans-cyclohexanedimethanol-dilactide. The polyacetal POE was also used as a matrix incorporating two different model drugs, caffeine and furosemide. Both polymers were ultrasonically molded into slabs. The lactide modified POE was also melt-extruded into rods and self-reinforced using a solid state die-drawing technique. The initial strength values of both ultrasonically molded and extruded samples were close to those of non-oriented poly lactic acids. Self-reinforcing increased the shear strength, bending strength and modulus of the rods from 41.7±1.7 MPa to 66.7±2.3 MPa, from 78.5±22.8 MPa to 183±23 MPa and from 2.5±0.3 GPa to 4.4±0.3 GPa, respectively. In vitro hydrolysis of samples was studied either in phosphate buffer saline (PBS) or in simulated body fluid (SBF) at 37 °C. Samples degraded faster in unchanged PBS than in PBS changed weekly. The total in vitro strength retention time was relatively short varying from 14 days to 42 days depending on the processing method and polymer type. Samples retained their wet weight at initial level for a longer time but dry weight started to decrease already after the first in vitro week. Polymers or degradation products crystallized in SBF but remained amorphous when hydrolyzed in PBS. Some of the devices showed evidence of surface erosion, and the processing method affected the erosion. The storage time of these polymers was found to be limited. However, both polymers were found to be of interest in bone fixation and tissue engineering. ©2000 Kluwer Academic Publishers Kluwer Academic Publishers, 2000 Kellomäki M. Institute of Biomaterials, Tampere University of Technology, P.O. Box 589, 33101, Tampere, Finland aut Heller J. Advanced Polymer Systems, 123 Saginaw Drive, 94063, Redwood City, CA, USA aut Törmälä P. Institute of Biomaterials, Tampere University of Technology, P.O. Box 589, 33101, Tampere, Finland aut Journal of Materials Science: Materials in Medicine Kluwer Academic Publishers 11/6(2000-06-01), 345-355 0957-4530 11:6<345 2000 11 10856 https://doi.org/10.1023/A:1008977806693 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1008977806693 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kellomäki M. Institute of Biomaterials, Tampere University of Technology, P.O. Box 589, 33101, Tampere, Finland aut NATIONALLICENCE 700 1- Heller J. Advanced Polymer Systems, 123 Saginaw Drive, 94063, Redwood City, CA, USA aut NATIONALLICENCE 700 1- Törmälä P. Institute of Biomaterials, Tampere University of Technology, P.O. Box 589, 33101, Tampere, Finland aut NATIONALLICENCE 773 0- Journal of Materials Science: Materials in Medicine Kluwer Academic Publishers 11/6(2000-06-01), 345-355 0957-4530 11:6<345 2000 11 10856 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer