title: Thermal treatment of expanded polytetraflu-oroethylene (ePTFE) membranes for reconstruction of a valved conduit.
abstract: The unique micro porous structure of expanded polytetrafluoroethylene (ePTFE) that allows bio-integration for fixation, as well as overall mechanical integrity make it used successfully in a number of biomedical and clinical applications, which include the reconstruction of the pulmonary valve in in right ventricular outflow tract reconstruction (RVOT) operations. The objective of this study was to determine the effects of the thermal treatment on physical and mechanical properties of ePTFE membranes. ePTFE sheets were cut into 16 rectangle strips (10 mm by 60 mm) and evenly separated into 4 groups. One group was the blank control (group A), while the rest of the three groups (group B to D) were heated to 350°C and cooled to 24°C at different cooling rates (10°C/min, 20°C/min and rapid ambient air cooling) in a temperature controlled atmosphere. The mechanical and morphological characteristics of all the samples were tested using a tensile test machine and a scanning electron microscopy (SEM). The results show that the elastic modulus of group B to D was 24.95%, 33.45% and 72.76% higher than group A. The percentage elongation of groups B to D was found to be between 2.3% and 40.45% lower than group A. The proportion of pores in the ePTFE membrane was reduced following the thermal treatment. There were no morphology differences observed between groups B to D. In summary, the selection of cooling rate was important for preserving the mechanical properties of ePTFE membranes under thermal treatment. These findings may provide useful information for the preparation of molded ePTFE valve in RVOT operations.
authors.affiliation: School of Energy and Power Engineering, Xi'an Jiaotong University, 28 Xian Ning West Rd, 710049, Xi'an, Shaanxi, China.|Department of Cardiothoracic Surgery, KK Women's and Children's Hospital, 100 Bukit Timah Rd, 229899, Singapore.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Zhu
authors.affiliation: School of Energy and Power Engineering, Xi'an Jiaotong University, 28 Xian Ning West Rd, 710049, Xi'an, Shaanxi, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yuan
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Ave, 639798, Singapore.
authors.forename: Joon
authors.initials: J
authors.lastname: Hock Yeo
authors.affiliation: Department of Cardiothoracic Surgery, KK Women's and Children's Hospital, 100 Bukit Timah Rd, 229899, Singapore.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Nakao
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis*; D055119:Elastic Modulus; D019544:Equipment Failure Analysis; D006350:Heart Valve Prosthesis; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008567:Membranes, Artificial; D011138:Polytetrafluoroethylene / Q000138:chemical synthesis*; D016062:Porosity; D011474:Prosthesis Design; D011664:Pulmonary Valve / Q000601:surgery*; D019651:Plastic Surgery Procedures / Q000295:instrumentation*; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011138:Polytetrafluoroethylene
keywords: Expanded polytetrafluoroethylene (ePTFE); mechanical properties; thermal treatment