Aleksandra Szalla

Surface modification of thin polymeric films by air-plasma or UV-irradiation

Abstract Commercial, purified poly(vinyl chloride) (PVC) in a form of thin film was used for modification by low-temperature air-plasma or short-wavelength UV-irradiation. The changes of surface properties were monitored by contact angle measurements allowing for calculation the surface free energy as well as its polar and dispersive components. Both modification sources cause surface oxidation of PVC films, which is connected with formation of functional groups enhancing polymer wettability. This process is very fast and efficient in air-plasma but slower during PVC exposure to UV. Storage of modified PVC indicates that in plasma also conformational changes occur. In case of UV-irradiated PVC secondary, dark reactions (mainly oxidation) take place during storage at ambient conditions.

Study of poly(acrylic acid)–poly(vinylpyrrolidone) complexes and their photostability

Abstract The poly(acrylic acid)(PAA)–poly(vinylpyrrolidone) (PVP) complexes with different stoichiometric ratio were obtained from aqueous solutions at different concentrations and pH values. The structure of complexes in solutions and in solid state has been studied using mainly FTIR spectroscopy. Least-square curve fitting method has been applied to calculate the contribution of different types of carbonyl groups (free and hydrogen bonded) in the PAA/PVP mixtures. Both polymers and their blends at different compositions were UV-irradiated (λ=254 nm ) in air. It has been found that PAA/PVP complexes are generally more photostable than pure polymers. This stabilisation effect was explained by the high amount of intermolecular hydrogen bonds reinforcing the polymer structure. Photocrosslinking is an additional factor influencing the stability of PAA/PVP complexes.

The influence of transition metal salts on photo-oxidative degradation of poly(ethylene oxide)

Abstract The influence of iron (III), cobalt (II) or nickel (II) chlorides on photo-oxidative degradation of poly(ethylene oxide) (PEO) has been investigated. The rates and efficiencies of photochemical reactions occurring in PEO containing small amounts (1–3%) of the transition metal chlorides were compared. The mechanism of reaction induced by UV-irradiation in doped PEO is discussed. The role of active Cl atoms and chlorine radical anion Cl 2 − (formed in the first step of metal salt photolysis) in initiation of polymer degradation is pointed out. The iron salt was found to be the most effective agent accelerating PEO photodegradation.

Changes of poly(ethylene oxide) photostability by doping with nickel(II) chloride

Abstract The influence of small addition of nickel(II) chloride on photooxidative degradation of poly(ethylene oxide) (PEO) in solution and in solid state has been investigated. Gel permeation chromatography, viscometry, differential scanning calorimetry, infrared and UV–Vis absorption spectroscopy has been used in these studies. It was found that nickel salt accelerates photodegradation and photooxidation of PEO. Photoinduced changes of PEO crystallinity and influence of macrochains conformation on the efficiency of photodecomposition has also been discussed.

Accelerated Degradation of Polymers

Abstract Application of photochemical processes for the environment protection against plastic waste has been shown in this communication. The ways of acceleration of decomposition of high molecular compounds including the effect of UV-radiation, metal salts and hydrogen peroxide are shown. The results of photo-oxidative degradation of selected commercial polymers using IR, UV-Vis spectroscopy, viscometry, gel permeation chromatography and optical microscopy has been presented.

Method of Utilization of the Spent Vanadium Catalyst

Abstract A spent vanadium catalyst, from the plant of metallurgical type, was leached in a potassium hydroxide solution to recover vanadium. The effect of time, temperature, concentration of basic, catalyst particle size and phase ratio was studied. The results showed that for a 160-750 μm catalyst leached for 4 h at 313.15 K in the presence of 10% potassium hydroxide solution at a liquid: solid ratio of 20:1, the extent of leaching of V was about 87%. Additionally, separation of vanadium from such a solution was investigated by the ion exchange method. Two types of polymer strongly basic ion exchangers were used. The ion exchange tests indicate that vanadium were loaded from the post-leaching solution with high effi ciency. On this basis a fl owsheet for the proposed process of a complex utilization of the spent vanadium catalyst is presented.