Abstract Nanostructured thermosetting materials based on matrices were prepared by modification of an epoxy system with linear PS‐ block ‐PB copolymers. The nanostructured thermosets obtained through PS segregation. Depending the block‐copolymer content in and its epoxidation degree, domains can display micellar, worm‐like or hexagonally‐packed cylinder structures, retaining stiffness matrix, where hexagonally cylindrical morphology lead to a significant increase fracture toughness....

Abstract The phase‐separation behavior and morphology of polycarbonate‐based polyurethanes were investigated as a function the soft‐segment molecular weight chemical structure 4,4′‐diphenylmethane diisocyanate/1,4‐butanediol based hard‐segment contents. Polarized optical microscopy atomic force images showed that surface morphologies changed content varied also when sample preparation conditions modified. An increase in soft‐ lengths led to increased phase separation with respect lower soft...

Abstract Summary: A wide range of epoxidized styrene‐block‐butadiene block copolymers were synthesized using hydrogen peroxide in the presence an situ prepared methyltrioctylammoniumtetrakis(diperoxotungstate)phosphate as catalyst system a water/dichloroethane biphasic system. 1 H NMR and FT‐IR spectra revealed that epoxidation procedure led mainly to 1,4‐epoxidized butadiene units. GPC analysis showed changed copolymer architecture into stars with fewer arms. The two glass transition...

Abstract Epoxy‐based blends containing poly(ethylene oxide)‐ co ‐poly(propylene ‐poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of generated morphologies and interactions between components on mechanical properties blends. Mechanical, morphological dynamic analyses indicate that observed increase flexural modulus can be related decrease free volume. In modified systems remain miscible, an modulus,...

Abstract The possibility of reacting chestnut and mimosa tannins with the intermediates synthesis reaction for phenolic novolacs under acid conditions has been proved using differential scanning calorimetry (DSC). amount intermediate compounds percentage free phenol formaldehyde in mixture is decisive determination stage which addition tannin suitable. Synthesis novolac resins modified 14 wt % extract or several percentages (until 40 %) have performed. pathways investigated by DSC, fourier...

Abstract The kinetics pathway of a 4,4′‐diaminodiphenylmethane‐cured diglycidyl ether bisphenol‐A (DGEBA) epoxy system modified with PEO–PPO–PEO block copolymer has been investigated by differential scanning calorimetry. curing progress this also studied dielectric relaxation spectrometry following changes in the main α‐relaxation. An interesting finding is change rate constant content. Infrared spectroscopy shows that due to interactions between hydroxyl groups growing thermoset and bonds...

Studies exploring gender differences in health-related quality of life (HRQOL) people living with HIV/AIDS (PLWHA) are scarce and contradictory. This study evaluated HRQOL 744 PLWHA median (IQR) age 44 (37-48) years HIV infection diagnosed 12 (5-20) earlier. Results showed important between genders (p < .05). Better male physical health was related to being employed, not having economic worries, receiving psychological support, injected drugs past, low negative mood HIV-related, illness...

Abstract The microstructure and fracture behavior of epoxy mixtures containing two monomers different molecular weights were studied. variation the toughness by addition other modifiers was also investigated. Several amounts high‐molecular‐weight diglycidyl ether bisphenol A (DGEBA) oligomer added to a nearly pure DGEBA monomer. cured with an aromatic amine, showing phase separation after curing. curing investigated thermal measurements. significant enhancement accompanied slight increases...

Abstract Triethylamine and sodium hydroxide catalyzed phenol/formaldehyde resole resins were investigated in terms of their behavior during both addition polymerization reactions. Amine‐catalyzed prepolymers mainly ortho‐substituted structures, whereas the catalyst directed reaction to para reactive sites. During polymerization, triethylamine led dimethylene ether bridges as principal linkages between aromatic increasing final concentration starting hydroxymethyl group increased. In...

Abstract The photoinduced graft copolymerization of acrylic acid with ultraviolet radiation onto films poly(vinyl chloride), polypropylene, and polyethylene was studied. Benzophenone used as the initiator for most experiments performed. percentage grafting determined by gravimetric measurements, characterization grafted carried out chemical analysis (Fourier transform infrared spectroscopy, volumetric titration, dye adsorption). In all samples, yield increased exposure time. High levels were...

The gang rape known as the "La Manada" case has had an unprecedented social impact in Spain. This research investigates how this been dealt with through Twitter by a collective symbolic coping process (Social Representation Theory). Discourse on was analyzed at two key points time: announcement of judgment and aggressors' release from prison. In total 6,592 tweets hashtag #lamanada were selected their content lexical analysis using Iramuteq software. results reveal both awareness phase about...

Abstract Blends composed of diaminodiphenylmethane bisphenol‐A epoxy resin and poly(ethylene oxide) (PEO) were prepared via in situ curing reaction the presence PEO. The miscibility blends before after was established by thermal (differential scanning calorimetry, DSC), microstructural (atomic force microscopy) dynamic mechanical analysis. Fourier transform infrared spectroscopy indicated that OH groups developed through cure reactions interact hydrogen bonding with After crystallinity...

Abstract Thermodynamic phase behavior was studied for polymer dispersed liquid crystal (PDLC) films consisting of blends different thermoplastics such as poly (bisphenol A carbonate) (PC), poly(methylphenylsiloxane) (PMPLSi), poly(styrene‐ b ‐ethylene oxide) (PSEO) block copolymer, and low‐molecular weight 4′‐(hexyloxy)‐4‐biphenyl‐carbonitrile (HOBC) crystals. The diagrams these PDLC systems were built up using thermal transitions determined by differential scanning calorimetry (DSC),...

Abstract Two commercial vinyl ester resins, Derakane 411‐350 (resin D) and Momentum M), were characterized. Despite the large quantity of publications in literature about few experimental results have been reported for resin M. The effect styrene content on mechanical properties morphological structure was studied. An increase produced a network with low storage modulus rubber state glass‐transition temperature. apparent average molecular weight between crosslink points temperature slightly...

Purpose – The purpose of this paper is to discuss the gender practices a female urban bus driver who retired after 40 years (1967-2007) in an company northern Spain. main objective study was explore and understand move from irreflexive reflexive perspective, uncover new key aspects relating influence women organizational changes. Design/methodology/approach This qualitative exploratory (interpretative phenomenological analysis (IPA)) contains semi-structured interviews which explore, using...

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Introducción: la inseguridad es un tema de preocupación social en Ecuador, así como muchos países latinoamericanos. La referencia a sucesos relacionados con habitual los medios comunicación y refleja situación incertidumbre que vive población cotidianamente. Objetivo: se plantea el análisis representación inseguridad. En este sentido, pretende conocer cómo jóvenes conciben explican objeto social. Metodología: mediante técnicas cualitativas, realizó recogida información. estudio, participaron...

Abstract A set of diglycidylether bisphenol‐A (DGEBA)/4,4′‐diaminodiphenylmethane (DDM) epoxy matrix modified with poly(ethylene oxide) (PEO), pre‐cured at two different temperatures, was examined by positron annihilation lifetime spectroscopy (PALS). The aim to investigate the correlation between local free volume and mechanical properties. negative deviation from linear additivity rule is observed both cure schedules. Using together results allows conclude that temperature makes small...