SBS/VP homograft membrane for oxygen enrichment

Abstract

The grafting of 4-vinyl pyridine (VP) onto styrene-butadiene-styrene triblock copolymers (SBS) by homografting irradiation with dissolved oxygen was studied. Homograft membranes of various degree of grafting were prepared from a casting solution of grafted copolymer in benzene. The mechanical properties of membranes, gas permeability, and the effect of operating temperature on gas permeation were investigated.The degree of grafting of 8.4% was the largest at an irradiation time of about 15.5 h. It was smaller at both shorter and longer duration because of the interference of dissolved oxygen. It was found that the tensile strength and elongation of SBS-g-VP were similar to those of SBS. The stress relaxation of SBS-g-VP was slower than that of SBS, and this might be due to the formation of rigid microphase separation domain of poly(4-vinyl pyridine), which acted as permanent crosslinking points to reduce the stress relaxation.Using the properties of high flux of SBS and high O,/N, selectivity of poly(4-vinyl pyridine), the performance of gas permeation of 4-vinyl pyridine homografted SBS membrane was studied. The selectivity of SBS-g-VP membrane increased with increasing degree of grafting. However, it was done at the expense of a decrease in the gas permeability.When the operating temperature of gas permeation increased, the permeability of oxygen and nitrogen increased, and the O,/N, permeability ratio decreased. The activation energy (Ep) for gas permeation through different degree of grafting of SBSg-VP membrane (obtained by the Arrhenius law) increased with increasing degree of grafting. For ungrafted SBS membrane, Ep was 5.5 kcal/mol for oxygen and 7.2 kcal/mol for nitrogen. For 8.4% grafting degree SBS-g-VP membrane, Ep for oxygen and nitrogen, were 6.5 and 8.1 kcal/mol, respectively. ZUSAMMENFASSUNGEs wurde die strahleninduzierte Pfropfung von 4-Vinylpyridin (VP) auf Styrol-Butadien-Styrol-Copolymere (SBS) in Gegenwart von geldstem Sauerstoff untersucht. Pfropfcopolymer-Membranen mit unterschiedlichen Pfropfgraden wurden durch Gie-Ben aus benzolischer L.iisung hergestellt. Die mechanischen Eigenschaften, die Gaspermeabilitat sowie der EinfluB der Temperatur auf die Gasdurchlassigkeit wurden untersucht. Der hachste Pfropfgrad von 8,4070 wurde bei einer Bestrahlungszeit von 15,s h erreicht. Sowohl bei kurzeren als auch langeren Bestrahlungszeiten war der Pfropfgrad bedingt durch Storung durch den vorhandenen Sauerstoffniedriger. ReiBfestigkeit und ReiBdehnung von SBS-g-VP waren vergleichbar rnit SBS. Die Spannungsrelaxation von SBS-g-VP war langsamer als bei SBS, was auf der Bildung von starren Polyvinylpyridin(DVP)-Mikrophasen beruhen konnte, die als permanente Vernetzungspunkte wirken und die Spannungsrelaxation beeintrachtigen ktinnten.Da SBS eine hohe Gasdurchlassigkeit und PVP eine hohe 0, /N,-Selektivitat aufweisen, wurde die Gasdurchlassigkeit der Pfropfmembranen untersucht. Die Selektivitat der SBS-g-VP-Membranen stieg rnit steigendem Pfropfgrad, allerdings auf Kosten der Permeabilitat, Bei Erhohung...

Wettability and antibacterial assessment of chitosan containing radiation‐induced graft nonwoven fabric of polypropylene‐g‐acrylic acid

“…Ikada et al1–8 reported on a series of studies of the surface modification of polymers for medical applications by graft polymerization methods. In our previous studies,9–15 the grafting of various vinyl monomers onto a membrane of thermoplastic rubber by the γ‐ray irradiation method was reported. Because graft polymerization is a time‐consuming and expensive oxygen degassing process in industrial applications, Uchida et al16, 17 reported on a method for surface graft polymerization of ionic monomer onto poly(ethylene terephthalate) by ultraviolet irradiation without degassing.…”