Search results for "Diethylene glycol"

1975

The density of crystals of poly(ethylene terephthalate), (PETP), Qc is checked by X-ray diffraction assuming a triclinic unit cell and the indices of reflections as found by Bunn. The following unit cell dimensions are found: a = 4,48A, b = 5,85A, c = 10,75 A, α = 99,5°, β = 118,4°, and γ = 111,2°. This gives the density Qc as 1,515g/cm3 which is about 4% higher than that reported by Bunn. Negligible differences in spacings for samples annealed at different temperatures (120°C–260°C) have been found. Only for an annealing temperature of 100°C the higher d-values lead to Qc = 1,484g/cm3. For undrawn PETP films annealed at 250°C the same value of Qc as for drawn PETP was obtained on the basis…

Theory-based improvements of continuous polymer fractionation demonstrated for poly(carbonate)

1992

For the first time, a quantitative theoretical analysis (liquid/liquid phase equilibria treated by means of the continuous thermodynamics) of the operating characteristics of continuous polymer fractionation (CPF) was performed. The results of these calculations were compared with data published for CPF of polyethylene. It turned out that the efficiency of the conventional CPF corresponds to approximately two theoretical plates only. For this reason, several improvements, suggested by theoretical considerations, were realized experimentally, for which purpose the system dichloromethane/diethylene glycol/bisphenol-A polycarbonate was chosen. The pulsating sieve-bottom column was replaced by …

Diethylene glycol (DEG)-associated myocardial changes: a pilot investigation of chronic intoxication in guinea-pigs.

1991

The myocardium of guinea pigs fed on sublethal doses of diethylene glycol (DEG) over a period of 2–11 days was examined for microscopical and ultrastructural changes. Coagulative myocytolysis and loss of myofibrils, not observed in the controls, was patchily distributed throughout the myocardium. The accompanying ultrastructural features included swelling, pleomorphism and hyperplasia of mitochondria with an associated distension of the interfibrillary spaces and a displacement, distortion and rupture of adjacent myofibrils.

An Easy Way Towardɛ-Caprolactone Macromonomers by Microwave Irradiation Using Early Lanthanide Halides as Catalysts

2002

Poly(e-caprolactone) macromonomers were synthesized under microwave irradiation from commercial caprolactone, using commercial hydrated lanthanide halides as catalysts. The molecular weight of the polymers was in the range 3 000–5 000. Higher molecular weights (5 000–20 000) and lower polydispersity indices were obtained with THF adducts of the lanthanide halides as catalysts and also by applying longer reaction times or using diethylene glycol as a coupling reagent.

1977

The reaction of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 3,6-dioxaoctane-1,8-diol (triethylene glycol), poly(ethylene oxide)s with Mn = 300,1000 and 3000, or with poly(propylene oxide)s with Mn = 425 and 2000 in excess with AIBN leads to the corresponding bis(hydroxyalkyl) 2,2′-azodiisobutyrates (1a–i). These initiators are suited to synthesize telechelics. With equimolar amounts of AIBN and 3-oxapentane-1,5-diol (diethylene glycol), poly(ethylene oxide)s with Mn = 300, 1000 and 12000, poly(propylene oxide) with Mn = 425, or with poly(tetrahydrofuran) with Mn = 1000 and 2000 polymeric azoinitiators of structure 2 are formed. Blockcopolymers may be synthesized by means of these polym…

Determination of antifreeze substances in the airport runoff waters by solid-phase microextraction and gas chromatography–mass spectrometry method

2016

Abstract A new method has been developed for the determination of antifreeze agents such as ethylene glycol (EG), propylene glycol (PG), and diethylene glycol (DEG) in the samples of airport runoff water. The method is based on headspace solid–phase microextraction (HS–SPME) of target analytes, which is coupled with gas chromatography–mass spectrometry (GC–MS). Until now, there was a lack of appropriate methodology for collecting reliable data about the concentration levels of these toxic de/anti-icing substances in the new type of environmental samples such as the airport runoff water. The evaluation of green extraction technique, i.e., HS–SPME resulted in establishing the optimal extracti…

Darstellung und eigenschaften von linearen oligourethanen mit phenylendgruppen und von cyclischen oligourethanen aus diäthylenglykol und hexamethylen…

1971

Es wurden lineare Oligourethane mit Phenylendgruppen und cyclische Oligourethane aus Diathylenglykol und Hexamethylendiisocyanat dargestellt. Der groste bisher isolierte Ring enthalt je sieben Grundbausteine und besitzt 119 Ringglieder bei einem Molekulargewicht von 1920. Eine gute Trennung der Oligomeren wurde durch Adsorptionssaulenchromatographie erzielt. Hierbei wurde ein Elutionsmittel mit Losungsmittelgradient verwendet. Schmelzpunkte, Umwandlungserscheinungen, Langperioden und Weitwinkeldiagramme der Oligomeren werden im Hinblick auf ihre Struktur diskutiert. Linear oligourethanes with phenylurethane endgroups and cyclic oligourethanes were prepared from diethylene glycol and hexamet…