EFFECT OF DRAWING ON THE STRUCTURE AND THE DYNAMIC-MECHANICAL BEHAVIOR OF SALTED POLYCAPROAMIDE.

Abstract Structural determinations, obtained through density, birefringence, and WAXS measurements, are reported for nylon 6/inorganic salt fiber samples as a function of draw ratio. They confirm the possibility of achieving very high amorphous orientation in these systems. Dynamic-mechanical data have also been collected which allow determination of glass transition temperatures. These are also discussed in terms of structural parameters.

A procedure is described for the preparation of a block copolymer with A-B-A sequences in which ω-ω′-dihydroxy-poly-(ethylene glycol) is inserted between two polymeric monoacidic chains of polycaproamide and bonded to them by means of ester links. The resulting material was characterized. The copolymer is isomorphous with the polycaproamide. Thermal treatments induce a crystalline transition γ α as in polycaproamide. The influence of the moisture content on the glass transition temperature and on the storage modulus is discussed. Ein Verfahren zur Herstellung eines Blockcopolymers mit A-B-A-Sequenzen wird beschrieben. In dem Copolymer ist ω-ω′-Dihydroxy-polyethylenglycol uber Esterbindungen…

THERMOTROPIC HOMOPOLYESTERS. IV. STUDY OF FIBER FORMATION.

We report a melt spinning and viscosity study of two semiflexible homopolyesters containing both rigid and flexible segments in the repeating unit. Single filaments of the polyesters formed from 4,4′-diacetoxybiphenyl and azelaic acid (PB7) and sebacic acid (PB8), and from 4′-hydroxyphenyl-4-hydroxycinnamate and azelaic acid (C7), were spun at temperatures between 205 and 255°C. The temperature dependence of the Newtonian melt viscosity of PB7 and C7 was investigated, and a range of molecular weights was studied for PB7. The spinning parameters, fiber characteristics, and viscosity-temperature behavior are related to the type of mesophase formed. The mechanical properties of fibers spun fro…

Preparation and mechanical characterization of fibres from a new copoly(ether-ester-amide) are reported. The mechanical characteristics are slightly lower than those of polyamide 6, but satisfactory for textile use, and the fibres have larger moisture absorption. This gives rise to more comfortable fibres preventing the accumulation of electrostatic charges. Die Herstellung und mechanische Charakterisierung von Fasern aus einem neuen Copoly(ether-ester-amid) werden beschrieben. Die mechanischen Eigenschaften sind etwas schlechter als die von Polyamid 6, aber ausreichend fur textile Anwendungen. Die Fasern weisen eine grosere Feuchtigkeitsabsorption auf. Dies fuhrt zu einem angenehmeren Verh…

Influence of processing conditions on some properties of anionically synthesized polycaprolactam in presence of lithium chloride

Nylon 6–LiCl systems of various concentrations were prepared by anionic polymerization of caprolactam in the presence of salt. A depression of both crystallization rate and melting temperature was evidenced through x-ray, density, and DSC analyses. Such a preliminary characterization allowed for choosing the proper conditions in order to obtain amorphous fibers from a spinning operation which was performed at a temperature lower than the pure polymer melting point. These results are of technological relevance, especially in view of obtaining, as in similar cases, large amorphous orientations through a spinning–drawing process and high-modulus fibers after subsequent crystallization. Also, t…

Crystal and molecular structure of the tris(1,10-phenanthroline)potassium salt of μ-hydridobis[pentacarbonylchromium(0)]

Abstract The crystal and molecular structure of [K(phen)3][Cr2(CO)10(μ-H)] has been determined by X-ray diffraction. The compound crystallizes in the space group P 1 with a 11.884(4), b 13.968(4), c 15.612(6) A, α 112.6(1), β 99.7(1) and γ 106.2(1)° and Z = 2. The structure was refined to R = 0.066 and RW = 0.067 for 3692 counter data with I ⩾ 3σ(I). The complex anion [Cr2(CO)10(μ-H)] adopts a bent Cr-H-Cr configuration with the equatorial carbonyl groups of the two independent Cr(CO)5 moieties in an eclipsed configuration. The Cr⋯Cr distance is 3.394(3) A and the two CrH bonds are 1.74(7) and 1.71(7) A. The CrHCr bond angle is 159(3)°. In the dimeric complex cation [K(phen)3]2, located …

Increasing the elastic modulus of polyamides

Synthesis, properties and X-ray crystal structure of schiff base organoimido complexes of rhenium(V)

Abstract Re(NR)Cl 3 (PPh 3 )( 2 (R = p-CH 3 C 6 H 4 , CH 3 ) react with polydentate ligands (LH = N-methyl-, N-phenyl-, N-tolyl-salicylideneimine, half, N,N′-ethylenebis-, half N,N′-propylenebis-(salicylideneimine), 8-hydroxyquinoline and LH 2 = N-2-hydroxyphenylsalicylideneimine) to yield complexes of the type Re(NR)Cl 2- (L)PPh 3 . With 8-hydroxyquinoline the bisubstituted Re(NR)Cl(L) 2 complexes are also obtained. The compounds were characterized by elemental analysis, molecular weight, and i.r. spectra. The crystal and molecular structures of two arylimido complexes, Re(p-CH 3 C 6 H 4 N)Cl 2 )RNCHC 6 H 4 O)PPh 3 with R = C 6 H 5 or CH 3 , were determined from X-ray crystallography base…

Hydrothermal synthesis of zeolites from rhyolitic pumice of different geological origins

Abstract Twelve samples of rhyolitic pumice from widely different origins were subjected to zeolitization in standard hydrothermal conditions (solid/liquid ratio, 1 5 ; T , 95°C; reaction time, 5 h; alkaline solution 5 N NaOH). The Si Al ratio of the starting material was of special importance in that zeolites formed with Si Al ratios similar to or smaller than that of the parent material. Pumice with low SiO 2 Al 2 O 3 , and high Fe content, preferentially gave rise to zeolites with lower SiO 2 Al 2 O 3 ratio than in the case of lower Fe and higher SiO 2 Al 2 O 3 ratio.