Properties of a new poly-ether-glycol copolymer.

Triblock copolymers are made of monomer segments, being the central part usually hydrophobic and the outer parts hydrophilic. By varying sizes, molecular weights and monomer types of the segments one obtains different final molecules, with different physico-chemical properties, which are directly related to the performance of the final product. Looking for new products to be used, among other possibilities, in biological applications, a new polymer (Figure 1) was synthesized by the Dow Chemical and studied by Size Exclusion Chromatography, Fourier Transformed Infrared Spectrometry, Small-angle X-ray Scattering (SAXS) and its cloud point was determined by measuring light transmittance. The studies showed low molecular polydispersivety, but different polarities in the macromolecules fractions. Due to the low solubility of Diol in water, a mixture of water/butyl diglycol was used as solvent. An extensive analysis by SAXS was performed for concentrations from 50 wt% to 80 wt% of Diol in solution. Small concentrations showed very low signal to noise ratio, making it impossible to be analysed. The scattering intensity including the form factor of polydisperse non-homogeneous spheres, and the structure factor of interacting hard spheres was fitted to the curves. As the polymer concentration is high, the fitting of form factors of direct and reverse micelles were compared. The results for direct micelles were better up to 80 wt%, whereas at 90 wt% and 95 wt% the curves were better fitted by reverse micelles. It might seem odd that direct micelles are present up to such high concentrations, but it might have been caused by the presence of butyl diglycol, which increases the solubility of Diol in water. The inner and outer radius of the micelles, electron density distribution, and interaction radius of the micelles were obtained. The polydispersivety increases with Diol concentration. Besides, the interaction radius increases with solvent concentration, even when reversed micelles are present. In the last case, accompanied by an increase of inner radius (water content), as there are fewer Diol molecules to involve the water nuclei, which become larger, further apart, and in less number.

The Acropolitan - v. 2, no. 3

In this issue...Butte, Anaconda, Silver Lake, Montana, Wilson Chemical Company, Seattle, Washington, Co-Ed Club, Professor Koenig, First-Year student course

Operation Characteristics of the Series System for Electrolytic Refining of Copper

In the copper electrolytic refining operation, two main objectives are desired: the first is the production of a metal of desired chemical composition and physical characteristics, and the second is the recovery of the valuable by-products.

A PROPOSED SAMPLE-BASED TECHNIQUE TO ESTIMATE THE STANDARDIZED MORTALITY RATIO

Evaluation of a series of deaths due to a particular disease is a frequently requested task in occupational epidemiology. There are several techniques available to determine whether a series represents an occupational health problem. Each of these techniques, however, is subject to certain limitations including cost, applicability to a given situation, feasibility relative to available resources, or potential for bias. In light of these problems, a technique was developed to estimate the standardized mortality ratio at a greatly reduced cost. The technique is demonstrated by its application in the investigation of brain cancer among employees of a large chemical company. ^

Biological treatment of high strength petrochemical wastewater /

Mode of access: Internet.

Infrared spectra of polymers and resins.

Cover title: Infrared spectra of plastics and resins.

"Grasselli dyes" & "Bayers dyes."

Contains mounted samples of dyed silk threads.

Planar vibrations of chlorinated benzenes,

Mode of access: Internet.

Physician's handbook.

Mode of access: Internet.

Penicillin : an annotated bibliography.

Vol. 2 also called Second Series.

Virginia pamphlets

A collection of miscellaneous pamphlets.

Ketones: acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK).

Mode of access: Internet.

Scientific water correction.

Mode of access: Internet.

An investigation into vibration criteria for rotating machinery

Concern had been expressed by engineers of the Shell Chemical Company regarding the validity of existing vibration criteria for rotating machinery. A survey showed that existing criteria were based solely on the amplitude of vibration, normally of the bearing housings, with no allowance being made for the dynamic properties of the support1ng structure. The feasibility of measuring the mechanical impedance of bearing supports in order to assess the severity of vibration generated by a machine has been investigated. It is suggested that in many cases the oscillatory bearing force levels obtained for these measurements will provide a quantitative indication of severity. Theoretical and experimental work has been conducted on a model rig, comprising a flexible shaft running in journal bearings housed in flexible, asymmetric supports. The accuracy with which the system behaviour could be predicted using measured support impedances is discussed together with the extraction of uncoupled support impedances from measurements on the complete rotating system. Access was available to several industrial centrifugal compressors. To enable the bearing support impedances of these machines to be measured on site considerable attention has been paid to the evolution of a technique involving the use of transient excitation. To develop this technique the model rig and a large rotary converter have been used as test structures. Methods have also been devised and developed for the analysis of the transient impedance data.

The Amplifier - v. 12, no. 5

In this issue...Canyon Creek Mine, Mineral Club, Geophysics Club, Rotary Foundation, Phil Judd, NASA, State Highway Department, Gasamat, Campus Parking