Polyether-polyester graft copolymer

Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer

Functioning of inorganic/organic battery separators in silver-zinc cells

The results of three experimental studies related to the inorganic/organic battery separator operating mechanism are described: saponification of the plasticizer, resistivity of the simulated separators, and zincate diffusion through the separators. The inorganic/organic separator appears to be a particular example of a general class of ionic conducting films composed of inorganic fillers and/or substrates bonded together by an organic polymer containing an incompatible plasticizer that may be leached by the electrolyte. The I/O separator functions as a microporous film of varying tortuosity with essentially no specific chemical inhibition to zincate diffusion

A review on tribological behaviour of polymeric composites and future reinforcements

Many different families of polymers are used in industries and engineering applications. The demands for studying the tribological behaviour of polymers and their composites are recently increased. This article briefs the most recent studies on the tribological behaviour of polymeric materials based on synthetic fibres. It reviews several factors which control the wear and frictional characteristics of such materials, that is, additives, fibres, interfacial adhesion, tribology environment, operating parameters, and composite geometry. In addition to that, new bioreinforcement (fibre) is introduced associated with preliminary results. The results showed that there is high potential of replacing the conventional reinforcement with the bioones

Polyphenylene ethers with imide linking groups

Novel polyphenylene ethers with imide linking units are disclosed. These polymers incorporate the solvent and thermal resistance of polyimides and the processability of polyphenylene ethers. Improved physical properties over those of the prior art are obtained by incorporating meta linked ethers and/or polyphenylene oxides into the polymer backbone. A novel process for making polymers of this type is also disclosed. The process is unique in that the expected need of high process temperatures and/or special atmospheres are eliminated

Spacecraft polymeric material interactions during decontamination, sterilization and thermal vacuum exposures

Spacecraft polymeric material interactions during decontamination, sterilization, and thermal vacuum exposure

Factors influence flexibility resistivity and zinc dendrite penetration rate of inorganic separators for alkaline batteries

Developmental work resulted in a formulation which can improve the flexibility of the inorganic-organic-type separator for silver-zinc and nickel-zinc alkaline batteries. The effects of various fillers and reactive organic additives on separator volume resistivity are described. The effects of various inert fillers on the zinc dendrite penetration rate of the separator are shown. Conclusions regarding the operating mechanism of the separator are presented

Polymeric membrane systems of potential use for battery separators

Two membrane systems were investigated that may have potential use as alkaline battery separators. One system comprises two miscible polymers: a support polymer (e.g., polyvinyl formal) and an ion conductor such as polyacrylic acid. The other system involves a film composed of two immiscible polymers: a conducting polymer (e.g., calcium polyacrylate) suspended in an inert polymer support matrix, polyphenylene oxide. Resistivities in 45-percent potassium hydroxide and qualitative mechanical properties are presented for films comprising various proportions of conducting and support polymers. In terms of these parameters, the results are encouraging for optimum ratios of conducting to support polymers

Seasonal erythemal UV, UVA and vitamin D effective UV exposures of office workers

In light of the ever changing composition of the Earth's atmosphere and the consequences of ultraviolet radiation (UVR) for the biological environment, it is important to be able to determine the specific ultraviolet radiation levels that reach humans living on the Earth's surface. Optimal human health requires a balanced amount of UV exposure as both too much and too little have different but serious potential health consequences. Sun damage can be caused by both UVB (280 320 nm) and UVA (320 400 nm) with melanoma and keratinocyte cancers being linked to UVB and UVA exposures. Humans need vitamin D to maintain good health and the best natural source of vitamin D is UVB from the Sun. Vitamin D deficiency, or insufficiency, is increasingly reported as people avoid potentially damaging UV exposure. Miniaturized dosimeters using polyphenylene oxide (PPO) as a photoactive material have been used to measure erythemal UV exposures received by humans for exposure periods of between one to seven days. In order to broaden the range of the PPO dosimeter, research was undertaken for the dual calibration of PPO dosimeters to both the erythemal and vitamin D action spectra. Through this dual calibration PPO dosimeters were able to record both types of biologically effective exposure as both are active within the UVB waveband. The calibration provided an R2 of 0.86 0.99 for erythemal UV and an R2 of 0.92 0.99 for vitamin D effective UV. A new miniaturized dosimeter using 8-methoxypsoralen (8-MOP) as the photoactive material was characterized and a technique developed for the calibration of UVA exposures. Using Mylar as a filter to remove the UVB, the spectral response showed that 8-MOP reacts only to wavelengths between 320 400 nm. The measured cosine response had an error of less than 14% for angles between 0° and 50°. Seasonal dose response tests indicated that these UVA dosimeters are able to measure exposures greater than 21.5 kJ/m2 for a continuous period of up to seven days. These two dosimeters were combined into one dosimeter badge; these combined badges were worn in research to record concurrently the personal erythemal UV, UVA and vitamin D effective UV exposures received by office workers in their occupational and recreational environments over a minimum period of a week in each season of the year. The amount of time spent outdoors, general UV protection strategies employed and the ambient UV both outdoors and within the office environment were recorded. Participants were all indoor office workers located at two sites at the sub-tropical location of Toowoomba (27°33'S 151°55'E, elevation 691 m). The participants wore a combined dosimeter badge horizontally on the shoulder for a minimum of one week in each season. The median erythemal exposure was highest during the spring and lowest during winter, as was the median vitamin D effective exposure. Median UVA exposures were at a similar level in winter and summer, autumn was higher and spring at a lower level. The behaviour of participants changed in each season; in winter 45% of the time spent outdoors was between the hours of 10:00 – 14:00 h compared to 27% in summer. The daily UVA/UVB ratio is also lowest between 10:00 – 14:00 h and also changes with the season, resulting in the differences between the distributions of exposures for each of the wavebands. Each category of exposures must be assessed individually as no association was found between any of the wavebands over the whole year, indicating that each season and each waveband had different distributions. Use of sunscreen, wearing of hats and type of clothing worn were analysed as part of the UV protection aspect of the study. Over 50% (n=128) of participants reported not using any sunscreen or wearing a hat at any time. Autumn rather than summer had the highest reported use of sunscreen and the highest proportion of people wearing hats. Clothing was separated into leg covering and arm covering. In all seasons, apart from winter, more than 25% (n=99) of participants always had short sleeves when outdoors. In winter 80% (n=29) of people had full leg cover and 30% (n=29) had full arm cover. These results indicate that the majority of people are not using UV protection on a regular basis. The results also demonstrate that, the dual film dosimeter developed and characterized with a calibration to three different biological responses, is an effective device for the concurrent measurement of the erythemal UV, UVA and vitamin D effective UV exposures for periods of a week before needing to change the dosimeters

Improved, low cost inorganic-organic separators for rechargeable silver-zinc batteries

Several flexible, low-cost inorganic-organic separators with performance characteristics and cycle life equal to, or better than, the Lewis Research Center Astropower separator were developed. These new separators can be made on continuous-production equipment at about one-fourth the cost of the Astropower separator produced the same way. In test cells, these new separators demonstrate cycle life improvement, acceptable operating characteristics, and uniform current density. The various separator formulas, test cell construction, and data analysis are described