Product category:
Particle size analysis equipment
News Release from: Wyatt Technology | Subject: Mals detectors
Edited by the Laboratorytalk Editorial
Team on 14 April 2008
Characterise polyurethanes in medical
devices
New application note from Wyatt Technology demonstrates the accurate and reliable characterisation of polyurethanes in medical devices
Wyatt Technology has published a new, free-of-charge application note to demonstrate the accurate and reliable characterisation of polyurethanes used in medical applications Wyatt's multi-angle light scattering (Mals) detectors were found to provide vital information about the molecular structure of polyurethanes when coupled to the company's innovative on-line ViscoStar viscometer
This article was originally published on Laboratorytalk on 9 Sep 2004 at 8.00am (UK)
Related stories
Making absolute particle sizing easy
Integrating field flow fractionation with multi-angle light scattering detection means that reproducible absolute particle sizing can be achieved without calibration or sizing standards
HPLC software reaches for the stars
Complements multi-angle light scattering detectors to make absolute molecular weight determinations a desirable alternative to traditional liquid chromatography methods
Polyurethanes are increasingly being used in medical applications, outperforming many other materials with regards to robustness, biocompatibility, hemocompatibility, flexibility, abrasion resistance and processing versatility.
Silicone, for example, is difficult to extrude and does not bond easily to non-silicone components.
PVC is associated with increased concerns regarding leachable plasticisers while becoming brittle at low temperatures.
Further reading
Refractive index detector is revolutionary
Innovative product is said to have 256 times the detection power and up to 50 times the dynamic range of any other RI detector in existence
Viscometer design moves ahead
Said to be the only viscometer that can measure intrinsic viscosity across the peaks of monodisperse samples, providing truly accurate readings for the first time
Applications include short-term implants, artificial hearts, catheter and general-purpose tubing, surgical drains, intra-aortic balloon pumps, dialysis devices and medical garments.
It is of utmost importance to test the structure-property relationships of polyurethanes prior to production in order to ensure that factors such as chemical composition, molar mass and molecular structure are within specifications to avoid possible fatal consequences to the device users.
Valuable information about the polymer structure and polymer-solvent interactions can be obtained from the log-log relation between the intrinsic viscosity and molar mass, called a Mark-Houwink plot.
The typical way to determine a Mark-Houwink plot involves preparing narrow fractions and their characterization with batch light scattering and a capillary viscometer.
However, this procedure is laborious and unsuitable for routine work.
An efficient and rapid way to generate Mark-Houwink plots is to couple a Mals detector to an on-line viscometer and size exclusion chromatograph.
Such a configuration can achieve excellent repeatability and accuracy for sensitive comparison of slightly different samples.
For this particular application, Wyatt's Sec-mals instrument and ViscoStar viscometer were combined to measure the Mark Houwink parameters of two polyurethanes.
The curvature of the two Mark Houwink plots indicated branching in both polymers.
In addition, the plots overlapped in the region of lower molar masses, indicating an identical degree of branching.
Deviation of the plots towards higher molar masses revealed a higher branching degree of the red polymer, the plot of which became flat at the region of higher molar masses.
This fact was explained by the presence of compact sphere-like fractions, which may be important for the final properties of the material.
• Wyatt Technology: contact details and other news
• Email this article to a colleague
• Register for the free Laboratorytalk email newsletter
• Laboratorytalk Home Page
Search the Pro-Talk network of sites
