Modification Of The Inner Surface Of Polyvinyl Chloride Tube By DC Glow Discharge Plasma

Narrow polyvinyl chloride (PVC) tubs are widely used in medical device for its excellent properties, such as smooth, light weight, corrosion resistance and low cost of production, etc. It is important to improve the inner-surface properties of the PVC tube to satisfy the medical standards. In this paper, the inner-surface of the PVC tube with 4mm inner diameter and 50 mm length were treated by DC glow discharge plasma. The effect of treatment time, gas flow rate and bias voltage on hydrophilic properties and inhibition of plasticizer leaching were investigated. The results are shown as follows:1) Improvement in hydrophilic propertiesThe water contact angle of inner-surface of the PVC tubes was remarkably improved after plasma treatment. The influence of treatment time, gas flow rate and bias voltage on the inner surface hydrophilic properties was investigated. It was found that the water contact angle of inner-surface decreased to 43°from 75°for untreated sample after 20 min treatment at 700 V and 30 SCCM gas flow rate. The improvement in hydrophilicity of the inner surface were enhanced with increasing treatment time and bias voltage, while were decreased with increasing the gas flow rate. The hydrophilicity of the inner surface degenerate while the plasma treated PVC tube was exposed in the ambient air, but it will reach a plateau after 72 hours. The plateau value is still significant better than that for the untreated one.2) Inhibition of plasticizer leachingBy using the extraction device developed in present work, the amount of plasticizer leaching from the inner-surface of the PVC tubes before and after plasma treatment was studied. The influence of treatment time, gas flow rate and bias voltage on the plasticizer leaching was investigated. The results show that the amount of plasticizer leaching from the inner surface of PVC tube significantly decreased after plasma treatment. After 192 h extraction, the amount of plasticizer leaching from the inner surface of PVC tube treated at 700 V and 30 SCCM gas flow rate for 20 min decreased to 122μg/ml from 304μg/ml for untreated sample.Under the same extraction time,the amount of plasticizer leaching from the inner-surface decreases with increasing the treatment time and increases with increasing gas flow rate,while electrode bias voltage has no significantly effect on it.