The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The 3-n-propyl-1-azonia-4-azabicyclo[2.2.2]octanechloride/silica hybrid polymer was synthesized, using the sol–gel method, by varying the organic content. The samples were characterized using infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N 2 adsorption–desorption isotherms and thermogravimetric analysis. The polymer morphology could be controlled by the choice and amount...
The physical aging of the epoxy network consisting of a diglycidyl ether of bisphenol A (BADGE n=0) and m-xylylenediamine (m-XDA) were studied by differential scanning calorimetry. The following aging temperatures have been used in this work: 60, 70, 80, 90, 100 and 110 °C. The glass transition temperature and the variation of the specific heat capacities have been calculated using the method based...
The effects of composition and compatibilizers on the molecular orientation in thermotropic liquid crystalline polymer (TLCP)/PP in situ composite films have been investigated using wide angle X-ray scattering (WAXS) techniques. The degree of preferred orientation for each component was evaluated using a novel separation technique based on a description of the scattering through spherical harmonic...
Spider dragline silk has a unique combination of desirable mechanical properties—low density, high tensile strength and large elongation until breaking—that makes it attractive from an engineering perspective [Nature 410 (2001) 541]. Nevertheless, this outstanding performance is threatened by the way mechanical properties are affected by a wet environment, particularly if the stress of these fibers...
We demonstrate that all solid polymers are intrinsically brittle and will undergo a ductile to brittle fracture transition based on the nature of their bonding alone. The most effective way of avoiding a ductile to brittle transition is to reduce the plastic resistance to delay reaching the brittle strength which in unoriented polymers is governed by intrinsic cavitation. While a number of possibilities...
The development of morphological solid-state structures in sulfonated poly(arylene ether sulfone) copolymers (acid form) by hydrothermal treatment was investigated by water uptake, dynamic mechanical analysis (DMA), and tapping mode atomic force microscopy (TM-AFM). The water uptake and DMA studies suggested that the materials have three irreversible morphological regimes, whose intervals are controlled...
Copolymerization of carbon dioxide and propylene oxide was carried out employing (RC 6 H 4 COO) 3 Y/glycerin/ZnEt 2 (R=–H, –CH 3 , –NO 2 , –OH) ternary catalyst systems. The feature of yttrium carboxylates (ligand, substituent and its position on the aromatic ring) is of great importance in the final copolymerization. Appropriate design of substituent...
Cold-drawn poly(ethylene terephthalate) (PET) samples annealed at different undercoolings are studied by means of differential scanning calorimetry and dynamic mechanical thermal analysis. When heating from room temperature, the onset of the glass transition region in cold-drawn, un-annealed samples is found to be significantly lower than in the case of un-oriented PET. On the contrary, the presence...
The kinetics of the individual key reactions involved in the formation of unsaturated polyester resins have been studied using the very reactive glycol, 2-methyl-1,3-propanediol (MPD). This diol has been reacted in turn with maleic anhydride (MA), phthalic anhydride (PA) and isophthalic acid (IA) under isothermal conditions in the temperature range 180–210 °C and the kinetic constants for the following...
We report the synergistic, rapid gelation of solutions of isotactic polypropylene (i-PP) and the nucleating agent 1,3:2,4-bis-(3,4-dimethyl benzylidene) sorbitol (DMDBS) in decalin. Cooling to room temperature of a solution comprising, for instance, 3.0wt% of a moderately high molecular weight i-PP (M v =1.3×10 6 g/mol) and as little as 0.0075wt% DMDBS (0.25wt% based on the polymer)...
A network model is applied to describe the deformation behaviour of melt-spun Nylon-6 fibres obtained at different spinning and drawing conditions. The network draw ratio is determined from analysis of true stress–strain curves and correlated with fibre orientation. From this analysis it appears that the deformation behaviour of Nylon-6 fibres adheres to a pseudo-affine mechanism. The results are...
The scale-up of the synthesis of high purity hydrogen-bonded supramolecular polymers is described. The synthesis involves functionalization of telechelic hydroxy-terminated poly(ethylenebutylene) with 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonding groups via dibutyltindilaurate catalyzed urethane formation. A procedure with optimized reaction conditions was developed and applied on a 10dm...
Liquid-crystalline polyesters with solubilizing side chains on aromatic rings have been synthesized by melt polycondensation of diacid dichlorides and silylated hydroquinones. Corresponding copolyesters incorporated with lactide units were obtained by addition of oligolactides. The molecular structures of these polymers were verified by spectroscopy techniques. Molecular weights were characterized...
Intercalated nanocomposites with poly(butylene terephthalate) (PBT) incorporated between the montmorillonite layers were synthesized from dimethyl terephthalate and 1,4-butane diol by using an in situ interlayer polymerization. The PBT nanocomposites were melt-spun at different organoclay contents to produce monofilaments. The samples were characterized by using wide angle X-ray diffraction, electron...
By addition of a small amount of poly(methyl methacrylate) (PMMA) into polystyrene (PS), we present a novel approach to inhibit the dewetting process of thin PS film through phase separation of the off-critical polymer mixture (PS/PMMA). Owing to the preferential segregation of PMMA to the solid SiO x substrate, a nanometer thick layer, rich in PMMA phase, is formed. It is this diffusive PMMA-rich...
A series of partial ladder copolymers were synthesized by chemically oxidative polymerization of m-phenylenediamine (MPD) and o-ethoxyaniline (EOA) using inorganic oxidants in inorganic acidic aqueous media. The polymerization yield, intrinsic viscosity, solubility, and thermal property of the copolymers were systematically studied by changing the comonomer ratio, initial polymerization temperature,...
Blown polyethylene (PE) film was exposed to UV irradiation while under tensile stress. Tests were conducted on unpigmented PE and on a series of five PEs containing TiO 2 pigments with different photo-activities. The yield strengths measured in tensile tests on unexposed films were typically 10% greater in the longitudinal (machine) direction than in the transverse direction. UV exposures...
Observations of individual lamellae within spherulites of linear polyethylene, drawn under affine conditions between room temperature and ∼100 °C, show lamellae surviving to sample failure, thereby providing a strong memory of the initial morphology in the final product. Lamellae rotate and deform according to the angle their plane makes with the draw direction. Those parallel to the draw direction...
We studied the effect of electrospinning parameters on the morphology and fiber diameter of regenerated silk from Bombyx mori. Effects of electric field and tip-to-collection plate distances of various silk concentrations in formic acid on fiber uniformity, morphology and diameter were measured. Statistical analysis showed that the silk concentration was the most important parameter in producing uniform...
The plane stress fracture toughness of amorphous copolyester (PETG) sheets plasticized by various amount of neopentylglycol dibenzoate (NPGDB in 0, 5, 10 and 20wt%) was studied in as-received (AR) and rejuvenated (RJ) states by adopting the essential work of fracture (EWF) method. EWF tests were performed on deeply double-edge notched tensile loaded (DDEN-T) specimens at various deformation rates...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.