Rapid survey analysis of polymeric materials by laser ablation-inductively coupled plasma spectrometry. An analytical note

An Nd-Yag laser (1064 nm) in combination with a multichannel emission spectrometer was used for rapid survey analysis of polymers and paints. A novel design feature of the ablation chamber was the incorporation of a graphite furnace to effect electrothermal pretreatments of samples. Transient emission signals were studied as a function of laser operating mode, laser duration and flashlamp energy.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Thermomechanical behavior of a polyphenylimide-quinoxaline

Linear polyphenylimide-quinoxalines (PPIQ) can be crosslinked by isothermal heat treatment in an inert atmosphere. To show this, three polyphenylimide-quinoxalines were prepared which differed only in molecular weight and polymer chain endings. Apparent activation energies of thermal crosslinking were then obtained from the rates of change of T_g as a function of time and temperature. The values (60 kcal/mole) were essentially the same as those for the thermal degradation of the same polymer in vacuum. Differences in polymer molecular weight had a distinct effect on the rates of change of T_g but the polymer chain ends seemed to have a lesser effect than previously observed on polyphenylquinoxalines (PPQ). Nevertheless, the rate of change in T_g is greater for PPIQ than for PPQ of a similar molecular weight. This indicates that the imide portion of the polymer chain leads to faster crosslinking under isothermal conditions.     

The determination of microgram amounts of beryllium using acetyl acetone

This paper describes the development of a method for the determination of μg quantities of beryllium using acetyl acetone. This reagent is first used to isolate the beryllium, after interfering elements have been complexed with ethylene diamine tetra-acetic acid. The beryllium is then determined absorptiometrically as the acetyl acetone complex using radiation of wavelength 2950 A. The method will detect 0.25 μg of beryllium with certainty and determine larger amounts with a precision of about ± 5 per cent.     

Micellisation and gelation of block-copoly(oxyethylene/oxybutylene/oxyethylene) E58 B17 E58

A triblock-copoly(oxybutylene/oxyethylene), denoted E₅₈ B₁₇ E₅₈ (80 wt-% E), was prepared by sequential anionic copolymerisation and its micellar and gelation properties in aqueous solution were determined. The oxybutylene/oxyethylene copolymer had the advantage over comparable oxypropylene/oxyethylene copolymers of greater uniformity of composition and chain length. The methods generally used were surface tension, light scattering intensity, photon correlation spectroscopy, together with observation of gelation. Measurements were made at 30°, 40° and 55° C over a full concentration range from dilute solution into the gel (>200 g dm^–3) and at specified concentrations, including the gel, over the temperature range from 10° to 70° C. The lower and upper temperature boundaries of the gel region were identified, and the occurrence of syneresis was noted. The properties investigated and discussed include critical micelle and gel concentrations, micellar weights and sizes, and structures and mobilities in the gel.