Effect of surface roughness and process parameters on mechanical properties of fabricated medical catheters

Breakage or separation of any catheter leads to a catastrophic adverse effect on a patient's life. Polyurethane material degradation and molecular instability during in vivo pose a major risk and cause deterioration of the medical functionality on achieving the required mechanical properties of the medical catheters. Experimental data on hand available are so far been from merchandised catheters, whereas the problem of the absence of manufacturing process technicalities exists. In this experimental study, medical catheters were fabricated in varying process conditions, for getting different surface characteristics. 12 Fr (4.00 mm) catheters were fabricated from medical grade Polyurethane (PU). The dimensional specifications were kept within the acceptable tolerance of product print. The surface roughness of catheters was evaluated using an Atomic Force Microscopy (AFM). Surface morphology was investigated through the use of a Scanning Electron microscope (SEM). A tensile testing machine with a special set up was utilized for the assessment of the mechanical properties of fabricated catheters. Tensile tests were conducted on the fabricated catheters for investigating the impact of surface roughness and chemical aging on elastic modulus (E), stress (σ) and strain (ε) at the break on the catheters. Native catheters, directly obtained from extrusion as well as chemically aged catheters were subjected to a tensile test for the exploration of the role of extrusion melt temperature and catheter surface roughness. Test results show that the catheters with a rougher surface having a strength reduction of 19% compared to smoother surface catheters. Moreover, chemical aging made a reduction in the catheter strength up to 80% of its initial strength. Statistical analysis was applied to the experimental data for the investigation of the effects of process temperature and the surface roughness of the medical catheter on its mechanical properties. The results led to the conclusion that the process melt temperature and surface roughness having a significant impact on the tensile strength of the medical catheters.