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The Rheological and Mechanical Performance of Polyvinyl Chloride/Ethyl Vinyl Acetate Formulations for Medical Device Applications
Author(s) -
Mcconnell D.C.,
Mcnally G.M.,
Murphy W.R.
Publication year - 2003
Publication title -
developments in chemical engineering and mineral processing
Language(s) - English
Resource type - Journals
eISSN - 1932-2143
pISSN - 0969-1855
DOI - 10.1002/apj.5500110204
Subject(s) - plasticizer , materials science , polyvinyl chloride , vinyl chloride , vinyl acetate , polyvinyl acetate , composite material , dynamic mechanical analysis , rheometry , rheology , copolymer , polymer
The incentive for this research is a result of the current issues arising over the use of flexible polyvinyl chloride (PVC) in medical devices, particularly with respect to their disposal and the use of migratory low molecular weight plasticisers. The debate at present involves consideration of the disposal of PVC by incineration, creating dioxins which environmentalists claim are harmful and the use of phthalates as leaching plasticisers which also present a health risk. This work investigates the suitability of ethyl‐vinyl acetate (EVA) copolymer as a permanent polymeric replacement plasticiser for use in flexible PVC formulations particularly for medical device applications. A range of powdered EVA copolymers and PVC formulations were compounded at ratios 100:0, 60:40, 50:50, 40:60 and 0:100 respectively. Two grades of EVA with 20% and 27% vinyl acetate (VAc) content and a grade of PVC with a K‐value of 71 were used in the investigation. Mechanical analysis was performed on injection moulded samples of these blends and the results showed that the tensile and flexural modulus decreased significantly with increasing EVA concentration. Rheological analysis was performed using dual capillary rheometry and the results showed only slight changes in shear viscosity with increasing EVA content even at lower shear rates. Dynamic mechanical thermal analysis showed partial miscibility of the PVC and EVA over the range of concentrations studied, thus indicating that EVA does have a plasticising effect on PVC.