TY - JOUR
T1 - Rheology and Extrusion of Medical-Grade Thermoplastic Polyurethane
AU - Lu, Guangyu
AU - Kalyon, Dilhan M.
AU - Yilgör, Iskender
AU - Yilgör, Emel
PY - 2003/12
Y1 - 2003/12
N2 - The selection of operating conditions and geometry for the processing of thermoplastic polyurethane, TPU, is a complicated task. This complication arises from the relatively high melting temperature of the crystalline hard blocks and the oxidative and thermal degradation and crosslinking that occur at temperatures that are relatively close to the melting temperature of the TPU. This article documents the rheology, extrusion, and structure development of a medical-grade TPU. The medical application requires that the additives commonly utilized in the development of polymeric resins, i.e., stabilizers, antioxidants, and lubricants, should be minimized; the TPU of this study contains no additives. At temperatures 10-20°C lower than the melting temperature of the TPU, the morphology of the hard blocks continues to evolve to generate a reversible increase in elasticity and shear viscosity of the TPU with increasing time. At temperatures greater than the melting temperature, the TPU undergoes degradation and crosslinking reactions, which give rise to a permanent increase in the elasticity and the shear viscosity of the TPU. The ramifications of the degradation and crosslinking at temperatures greater than 200°C and morphology modification upon the continuing evolution of the hard blocks at temperatures less than 200°C on the rheology and processing were investigated.
AB - The selection of operating conditions and geometry for the processing of thermoplastic polyurethane, TPU, is a complicated task. This complication arises from the relatively high melting temperature of the crystalline hard blocks and the oxidative and thermal degradation and crosslinking that occur at temperatures that are relatively close to the melting temperature of the TPU. This article documents the rheology, extrusion, and structure development of a medical-grade TPU. The medical application requires that the additives commonly utilized in the development of polymeric resins, i.e., stabilizers, antioxidants, and lubricants, should be minimized; the TPU of this study contains no additives. At temperatures 10-20°C lower than the melting temperature of the TPU, the morphology of the hard blocks continues to evolve to generate a reversible increase in elasticity and shear viscosity of the TPU with increasing time. At temperatures greater than the melting temperature, the TPU undergoes degradation and crosslinking reactions, which give rise to a permanent increase in the elasticity and the shear viscosity of the TPU. The ramifications of the degradation and crosslinking at temperatures greater than 200°C and morphology modification upon the continuing evolution of the hard blocks at temperatures less than 200°C on the rheology and processing were investigated.
UR - http://www.scopus.com/inward/record.url?scp=1542605294&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=1542605294&partnerID=8YFLogxK
U2 - 10.1002/pen.10158
DO - 10.1002/pen.10158
M3 - Article
AN - SCOPUS:1542605294
SN - 0032-3888
VL - 43
SP - 1863
EP - 1877
JO - Polymer Engineering and Science
JF - Polymer Engineering and Science
IS - 12
ER -