Surface modification of ultrafiltration membranes by low temperature plasma II. Graft polymerization onto polyacrylonitrile and polysulfone

Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV) damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degradation. In this present study, the effects of UV light on the chemical, mechanical and physical properties of cured epoxy structure, as well as the effect of an organic UV absorber, Tinuvin 1130, on the epoxy properties were investigated. Chemical changes in a cured epoxy system as a result of the presence and absence of Tinuvin 1130 were determined using Fourier transform infrared spectroscopy (FT-IR) analyses. The effect of Tinuvin 1130 on the surface morphology of the epoxy systems was also investigated by scanning electron microscopy (SEM) imaging. Additionally, the glass transition temperatures (Tg) before and during UV radiation were measured. After an 800 h UV radiation, mechanical test results revealed that the lack of the UV absorber can lead to a ~30% reduction in tensile strength. However, in the presence of Tinuvin 1130, the tensile strength was reduced only by ~11%. It was hypothesized that the use of Tinuvin 1130, as an organic UV absorber in the epoxy-amine system, could decrease the undesirable effects, arising from exposure to UV light.

/pdf/the-effects-of-uv-light-on-the-chemical-and-mechanical-4m21box2ke.pdf

The Effects of UV Light on the Chemical and Mechanical Properties of a Transparent Epoxy-Diamine System in the Presence of an Organic UV Absorber

https://www.dora.lib4ri.ch/eawag/islandora/object/eawag%3A14377/datastream/PDF2/Bourgin-2017-Effect_of_operational_and_water-%28accepted_version%29.pdf

Effect of operational and water quality parameters on conventional ozonation and the advanced oxidation process O 3 /H 2 O 2 : kinetics of micropollutant abatement, transformation product and bromate formation in a surface water

Modification of polysulfone membranes 1. CO2 plasma treatment

Role of metals and metal-deactivators in polymer degradation

Elevated temperatures and high humidity decrease the molecular weight and impact strength of polycarbonate. Hydrolysis of injection molded polycarbonate (PC) bars stored in glass containers at 85°C and 96% relative humidity (RH) produced brown surface crystals within 30 days. Aging of PC bars at 96% RH and temperatures of 70°C and lower for longer periods of time formed a brown liquid coating on the PC. X-ray, DSC, and GPC measurements indicated that about 70 wt% of the surface crystals were bisphenol A (BPA). The remaining portion of hydrolysis products appeared to be higher molecular weight oligomers of BPA. The brown liquid was composed of supercooled liquid BPA, BPA oligomers, and water. Initial growth of BPA on the surface of a PC bar took place at the interface between the PC and the glass wall of the container. Apparently a water soluble extract from the glass container accelerated the hydrolytic degradation of PC; nevertheless, hydrolysis of PC occurred in the absence of glass—although at a slower rate. Hydrolysis studies were carried out on several commercial PC formulations. The PC resin containing only a heat stabilizer was least affected. Of the fiame retardant grades, the brominated PC hydrolyzed less rapidly than these particular compositions containing alkali metal sulfonic acid salts. A glass fiber reinforced PC was less stable than its unfilled parent compound. A hydrolytic stabilizer was ineffective against the attack of water under these conditions.

Hydrolysis of polycarbonate to yield BPA

Polysulfone, polycarbonate, and phenoxy resins were aged under thermal and ultraviolet light conditions. Thermoxidative processes in polysulfone and polycarbonate are of such minor significance as not to impart noticeable losses in these materials below 125°C. In phenoxy, however, thermal oxidation above 100°C results in rapid deterioration of all physical properties. This probably results from the low glass transition temperature of this polymer. Photo-oxidation rapidly degrades polysulfone. This appears to be a consequence of scission at the sulfone link. In polycarbonate, however, the only serious result of short-term irradiation is discoloration. For phenoxy resin, crosslinking through reactions at the hydroxyl group is the principal result of photo-oxidation. In all processes the bisphenol A portion of the three polymers appears to play only a small role.

Oxidation of bisphenol a polymers

The thermal oxidation and photo-oxidation of poly(2,6-dimethyl-1,4-phenylene oxide) have been examined. Oxidation of the plastic results in the evolution of carbon dioxide, nitrogen and traces of hydrogen, the introduction of considerable crosslinking, and increased absorption in the hydroxyl and carbonyl regions of the infrared spectrum. A free-radical oxidation mechanism is postulated.

Thermal oxidation and photo‐oxidation of poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Commercial thermoplastics may be classified by the types of rate curves obtained on thermal oxidation. The rate of oxidation of an acrylonitrile-butadiene-styrene plastic is affected by sample thickness and appears to be diffusion-controlled. Pigmentation increases the reaction rate of this compound in all the cases studied because of the catalytic effect of the metals present. Carbon black adversely affects the oxidation rate of stabilized polypropylene. The acetal plastics decompose under oxidative condition at 140°C. Of the thermoplastics examined, polytetrafluoroethylene, fluorinated ethyleneproplyne copolymer, poly(vinylidene fluoride), poly(ethylene terephthalate), and polysulfone are the most resistant to thermal oxidation at 140°C.

Thermal oxidation of thermoplastics

Infrared spectroscopy was used to study the thermal oxidation, accelerated and natural photooxidation of acetal homopolymer and copolymer. Chain scission is the predominant reaction, as revealed by changes observed in the hydroxyl, carbonyl, and methylene absorption regions of the infrared spectra. Photolysis accelerates the degradation of both plastics. Reaction mechanisms are presented to explain the behavior of these materials under oxidative conditions.

Investigation of thermal oxidation and photooxidation of acetal plastics by infrared spectroscopy

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