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Two types of SAXS and WAXS experiments have been made using synchrotron radiation to observe the transformation from smectic to crystalline phases in oriented poly(ethylene terephthalate) (PET). In step-anneal experiments, PET was drawn slowly at 30 °C and then observed after annealing at 5 °C steps up to 100 °C. In the other experiments, time-resolved observations were made while drawing at 90 °C...
A new modification direction of acrylonitrile, vinyl acetate and divinylbenzene terpolymers (A, B) are presented. The aminolysis of nitrile groups of the terpolymers using ethylenediamine or hydroxylamine hydrochloride was a first stage of the modification. The resulting amine groups reacted with dicyandiamide (DCDA), cyanamide (CA) and sodium dicyanimide (SDC) in order to obtain the biguanidyl, guanidyl...
The isothermal crystallization of three random copolymers of ε-caprolactone with different contents of 2,2-dimethyltrimethylene carbonate (DTC) (DTC: 5, 9 and 18mol%) and poly(ε-caprolactone) (PCL) was studied using DSC and PLM methods. The isothermal crystallization data were analyzed with the Avrami equation. The exponent n, from 3 of PCL to 2 of P(82%CL-ran-18%DTC), suggests a change of crystal...
A low-molecular-weight poly(ethylene oxide) (PEO) fraction with a number-average molecular weight of 4250 g/mol was used to study the melting and recrystallization behaviors during heating. After complete crystallization at 46 °C, the PEO possessed almost exclusively once-folded chain [IF(n=1)] crystals and very few extended chain IF(n=0) crystals. Comparing differential scanning calorimetry heating...
Polyimide/inorganic hybrids were prepared by sol–gel reaction starting from tetraethoxysilane (TEOS), and tetrabutyl titanate (TBT) in the solution of polyamic acid in N,N-dimethylformamide. The hybrid films were obtained by the hydrolysis-polycondensation of TEOS and TBT in polyamic acid solution, followed by the elimination of solvents and imidization process. Binary polyimide/SiO 2 and...
A project was carried out aimed at reducing the coefficient of thermal expansion (CTE) of photosensitive polyimide formulations (photoresists) through the incorporation of small amounts of an organoclay. The organoclay was formed by a cation exchange reaction between a NA + -montmorillonite clay and an ammonium salt of dodecylamine. Two polyimide precursors, a poly(amic ester) (PAE) and a...
Raman microscopy is applied to a gel-spun UHMWPE-fibre (Dyneema SK60) to determine the distribution of axial molecular stresses and their change with time (in creep and during stress relaxation). A more detailed method is proposed to quantify the observed characteristic changes in local stress distribution. The increase in highly overstressed bonds (5–8 GPa) is ascribed to the straining of tie-molecules...
This paper reports on the microstructure and deformation of one type of high modulus cellulose fibre characterised using the techniques of Raman spectroscopy and synchrotron X-ray diffraction and it compares this fibre to a lower modulus conventional viscose fibre. The crystallinity of the fibres has been determined using X-ray diffraction. The orientation parameter has been determined by measuring...
Epoxy resin networks have been modified with block copolymer of polybutadiene and bisphenol A diglycidyl ether (DGEBA)-based epoxy resin. Block copolymers prepared from isocyanate-terminated polybutadiene (NCOPBER) resulted in cured transparent epoxy networks with no discernible phase-separated morphology, as indicated by scanning electron microscopy. Epoxy resin modified with block copolymer derived...
Among the various inorganic nucleators examined, Talc and an aluminum complex of a phosphoric ester combined with hydrotalcite (NA) were found to be effective for the melt-crystallization of poly(l-lactide) (PLLA) and PLLA/poly(d-lactide) (PDLA) stereo mixture, respectively. NA (1.0phr (per one hundred resin)) can exclusively nucleate the stereocomplex crystals, while Talc cannot suppress the homo...
Blending poly(ethylene glycol) (PEG) with poly(lactide) (PLA) decreases the T g and improves the mechanical properties. The blends have lower modulus and increased fracture strain compared to PLA. However, the blends become increasingly rigid over time at ambient conditions. Previously, it was demonstrated that a PLA of lower stereoregularity was miscible with up to 30wt% PEG. Aging was due...
This article reviews recent advances in research of helical conformations of optically active polysilylenes in solution. The helical conformation induces strong circular dichroism, chain stiffness, and liquid crystallinity in polysilylene chains, and it sensitively affects electronic state in the σ-conjugated silicon backbone. The helical conformation is determined by the internal rotation potential...
Molecular orientation and strain-induced crystallization of vulcanized natural rubbers (by sulfur and peroxide) and synthetic polyisoprene rubber (by sulfur) during uniaxial deformation at 0 °C were studied by in situ synchrotron wide-angle X-ray diffraction. The high intensity of synchrotron X-rays and new image analysis methods made it possible to estimate the mass fractions of strain-induced crystals...
The formation of phase morphology of injection molded HDPE/EVA blends, under the effect of shear stress, has been investigated in detail. The shear stress was induced by dynamic packing injection molding, by which a specimen is forced to move repeatedly in the model by two pistons that move reversibly with the same frequency during cooling. Two kinds of EVA with VA content 16wt% (16EVA) and 33wt%...
The behavior of thiophenol and aliphatic thiols of different structure as chain transfer agents in the polymerization of acrylamide and 1-vinyl-2-pyrrolidone in aqueous solution at 25 °C was studied. Addition of millimolar concentrations of thiols to acrylamide polymerization reduced notably the polymer molecular weights, without change of the polymerization rate. Measurements at different pH showed...
Poly(lactide) (PLA) is rapidly gaining interest as a biodegradable thermoplastic for general usage in degradable disposables. To improve mechanical properties, a PLA with low stereoregularity was blended with polyethylene glycol (PEG). Blends with up to 30wt% PEG were miscible at ambient temperature. Blending with PEG significantly decreased the T g , decreased the modulus and increased the...
Poly(methyl methacrylate) (PMMA) is used to model the relaxation and plastic flow mechanisms of deformation, and the characteristic stress–strain response, relating it to its structure as much as it is known. The scope of this work is to identify and quantify the micro-mechanisms and the corresponding stress–strain relationships, and to assemble these into a coherent and self-consistent model for...
This paper examines the influence of processing parameters on the physical properties and structure of yarns constructed from poly(l-lactic acid) (PLLA) fibres. Commercially produced spun- and false-twist texturised (FTT) PLLA yarns, and knitted fabrics derived there from were characterised in terms of their tensile properties, and structurally using differential scanning calorimetry (DSC) and wide...
Simultaneous measurement of X-ray diffraction and Raman spectra has been performed for studying the structural changes in the photoinduced solid-state polymerization reaction of diethyl Z,Z-muconate (EMU) single crystal. As the reaction proceeded, the X-ray reflections coming from the polymer species started to appear and shifted the positions toward those of the finally attained polymer product....
Spectroscopic techniques have the potential to provide powerful, molecular-specific, non-invasive measurements on polymers during melt processing operations. An exploration is reported of the application and assessment of sensitivity of in-process vibrational spectroscopy—on-line mid-infrared (MIR), on-line near-infrared (NIR), in-line NIR and in-line Raman—for monitoring of single screw extrusion...
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