Aristides H. Kehayoglou

Copolymers of anionic polymerization of octanelactam with laurolactam (nylon-8/12 copolymers)—I. Preparation and general properties

Abstract Thermoplastic statistical copolyamides from nine mixtures of octanelactam (OL) and ω-laurolactam (LL) and also the corresponding homopolymers (nylon-8 and nylon-12) were obtained in high yields by activated anionic copolymerization at 180°C, using sodium hydride as catalyst and N -phenylcarbamoylcaprolactam as activator. The proportions of co-units in the copolymers (freed from oligomers) were determined by elemental analysis, u.v. spectroscopy and NMR. Samples were also characterized by T m , [ n ], d (g/cm 3 ), M n (osmotic), amino-end groups content and interplanar spacing (X-ray). The results are correlated with the molar ratio of the comonomers (OL/LL) and discussed. Minima for T m and crystallinity were indicated for the copolymers of 50 50 - 60 40 OL/LL molar compositions.

13C NMR spectra of nylon 6/12 copolymers and related model compounds

Abstract The 13C NMR spectra of model mono- to tetra-amides containing CO, (CH2)5 and (CH2)11 groups in varied sequential arrangements have been used to reinterpret assignments previously proposed for signals in the spectra of nylon 6/12 random copolyamides. From the CO signal intensities, the mean nylon 6 and nylon 12 homo-unit block lengths have been determined in copolyamides prepared by rapid (ca. 15 min) activated anionic lactam copolymerisation at 180°C. The results are virtually identical with published data for equilibrium copolymers of similar co-unit ratios made by hydrolytic polymerisation at 260°C in reaction times >144 h. Maximum sequential randomness occurs at ca. 50–60 mol% nylon 6 component, coinciding with minima in the thermal and solid-state properties.

Anionic copolymers of octanelactam with laurolactam (nylon-8/12 copolymers): 3. Glass transitions, heats of fusion, crystallinity and specific heats☆

Abstract Glass transition temperatures (Tgs), heats of fusion and crystallization and specific heats in the solid phase, for a series of statistical copolyamides (nylon-8/nylon-12), prepared by activated anionic polymerization of octane-/laurolactam (OL/LL), were determined and the results were correlated with the molar composition of the copolyamides and discussed. Minima for Tg and the heat of fusion for the initial melting and maxima for T g initial melting point (Tm) and changes in specific heat values were indicated for copolyamides with 50 50 – 60 40 molar compositions.

Polyurethanes from 4,4'-diphenylmethane diisocyanate and poly(oxyethylene) glycols. I. Preparation and general properties

Linear polyurethanes (PU) from 4,4′-diphenylmethane diisocyanate and an equimolar quantity of poly(oxyethylene) glycol (PEG) of various molecular weight (106, 200, 400, 1000, 2000, and 4000) were obtained by polymerization using 4-methylpentanone-2 as solvent at 115 °C. Alternative reaction conditions and melt polymerization were also applied. Samples were characterized by elemental analysis, solubility, I.R. spectroscopy, DSC (Tm, Tg ), [n] and [Mbar]n (osmotic). The results are correlated with the molecular weight of PEG and discussed.

Aromatic Poly(α- and β-naphthylamino)amides and Poly(α and β-naphthyl)benzodiimidazoles. II

Abstract Two new tetraamines, l,5-di(α- and β-naphthylamino)-2,4-diaminobenzene, are prepared and used in a low-temperature solution polymerization with terephthaloyl and isophthaloyl chloride or 2,5-furoyl dichloride. The newly prepared poly-(α- and β-naphthylamino)amides are converted by polycyclo-dehydration with heating to the corresponding new heat-resistant poly(α- and β-naphthyl) benzodimidazoles. The prepared polymers are characterized and the influence of the bulky naphthyl substations on their solubility and on the thermal stability of the poly(naphthyl)benzodiimidazoles with respect to the corresponding unsubstituted polymers is discussed.

Identification of nylons by thin layer chromatography

The composition of nylons by ω-amino-carboxylic acid monomers, dicarboxylic acids, and diamines is identified by thin layer chromatography, using their acid hydrolysates and determining the corresponding Rf values. Die Zusammensetzung von Nylon aus ω-Aminocarbonsauremonomeren bzw. Dicarbonsauren und Diaminen wurde mittels Dunnschichtchromatographie durch Bestimmung der entsprechenden Rf-Werte der Saurehydrolysate ermittelt.