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The present work studied factors which may affect phase transfer-catalyzed (PTC) nucleophilic displacement reactions, including chloromethylated polystyrene as polymer-supported alkylating agent and 4-hydroxybenzaldehyde as an 0-nucleophilic reagent in presence of representatives for phase transfer catalysts. Some polymer-analogue conversions using the resulting polymer-supported aldehyde have been carried out.


For blends of a poly(methyl methacrylate) (PMMA) and a poly(vinylidene fluoride-co-hexafluoro acetone) [P(VDF-HFA)], we examined phase behavior and crystalline melting (T m) and glass transition (T g) temperatures. In the range 130–160°C, which is a miscible one-phase region between their lower critical solution temperature (LCST: T c ¼ 220°C; f c ⬵ 0.5) and T m ( ⬵ 120°C) of P(VDF-HFA), simultaneous measurements of transient tensile stress j(t) and birefringence Dn(t) were conducted via elongational flow opto-rheometry (EFOR) on the blends under uniaxial elongation at constant Hencky strain rates. The stress optical coefficient C(t)( ⬅ Dn(t)/j(t)) increased monotonically with increasing volume fraction f P(VDF-HFA) of P(VDF-HFA) in the blend. Molten PMMA/P(VDF-HFA) blends in the one-phase region appear to follow the stress optical rule with C(t) obeying the simple additivity: C(t) ¼ C P(VDF-HFA)f P(VDF-HFA) þ C PMMAf PMMA with the suffices being relevant to each component. The value of C(t) extrapolated to f P(VDF-HFA) ¼ 1 yielded C P(VDF-HFA) ¼ 6.5 х 10 ¹9 Pa ¹1. The C(t) vs f P(VDF-NFA) behavior suggested that C(t) can be zero for the (97/3) blend or the addition of only 3% P(VDF-HFA) to PMMA makes the blend non-birefringent. Thus, P(VDF-HFA) can be an optimal modifier when PMMA is used as a high-technology optical material, e.g., optical discs and lenses.


We have investigated the structural relaxational behavior of poly(propylene glycol), PPG, for polymer chains of increasing number of monomer units, n( ˆ 3, 7, 70), and for different end groups (OH and CH3) using Brillouin scattering and dielectric relaxation. In the case of the OH capped systems the relaxation dynamics are rather insensitive to chain length variations, whereas large effects are demonstrated when changing to CH3 end groups. For chains with n > 20, there is a radical decrease in the sound velocity and the average relaxation time, when the hydroxyl terminations are replaced by methyl terminations. By using the nonpolar CH3 endcapping the linking of adjacent chains, as is the case in the hydrogen bonded OH capped systems, is avoided.


We found that dimethyl sulfoxide (DMSO) dissolves PAAm. Direct N-alkylation of the amide groups of polyacrylamide was performed under homogeneous condition in DMSO. By using tert-butoxide, the amide groups of PAAm were turned into amide cations, followed by a coupling reaction with alkyl bromide to give N-alkylated PAAm. 1H NMR suggests that the incorporation of alkyl bromide proceeded quantitatively. Intrinsic viscosity measurements and 13C NMR spectra in DMSO suggest that undesirable side reactions such as cross linking or hydrolysis of the amide groups did not take place during the reaction.


The orientation induced by stretching uniaxially in the solid state two semi-crystalline miscible blends of poly(e-caprolactone) (PCL) with poly(viny1 chloride) (PVC) and poly(styrene-co-acrylonitrile) (SAN) was investigated by infrared dichroism. In both cases, the deformation of the solution-cast films, having a high PCL crystallinity degree of about 50% and containing up to about 40 wt% of PVC or SAN, leads rapidly to a very high segmental orientation for the crystalline PCL as a result of a structural transformation from lamellae to microfibrils. Meanwhile, the amorphous components, being miscible and located in the interlamellar regions inside the spherulites, show a much lower orientation as compared with the crystalline PCL regardless of the blend composition. SAN is found to orient to the same degree as the amorphous PCL in the PCWSAN blends, while the orientation of PVC is higher than that of the amorphous PCL in the PCL/PVC blends. Furthermore, the slow crystallization of PCL in blends containing around 40% of PVC made it possible to follow the orientation behaviour as a function of the crystallization time by stretching a series of films before and after the crystallization of PCL started. It was found that, even with as little crystalline PCL as 5% of the total blend weight, the stretching-induced crystalline orientation is almost as high as for the samples with high degrees of crystallinity. A stretching-induced crystallization forming microfibril-like crystallites of PCL is suggested to be at the origin of the high crystalline orientation for those blends, which have a dominant proportion of amorphous components during the stretching, instead of the transformation of existing lamellae to the microfibrillar structure for stretched highly crystalline blends


The miscibility and phase behaviour of poly(hydroxy ether of bisphenol-A) (phenoxy)/poly(methyl methacrylate) (PMMA) blends were investigated using Raman microscopy. It was shown that while phenoxy/PMMA blends prepared by casting from chloroform at room temperature are immiscible, the blends prepared at high temperature are miscible. The Raman technique revealed the shift of the PMMA carbonyl stretching band in the miscible blends and its absence in the immiscible blends. This may be explained by the presence of specific interactions between the groups in phenoxy and PMMA due to the increased chain mobility during the mixing at high temperature. The changes of the special features in the Raman spectra were found to be useful in identifying different phase structures and their compositions in the blends.


Molecular interactions in miscible polymer blends influence glass transition (Tg) behaviour and the increment of heat capacity at Tg. Whether the glass transition temperature and the increment of heat capacity versus composition show positive or negative deviations from linearity for blend systems depends on specific molecular interactions. In the non-interacting system, poly(vinyl acetate)/poly(methyl acrylate), the glass transition temperature and the increment of heat capacity show a linear behaviour with composition. Thermodynamic theoretical considerations concerning the non-linear behaviour of the glass transition temperature and the increment of heat capacity with composition in miscible polymer blends are developed in this paper.


Compatibility of cellulose acetate hydrogen phthalate (CAP) and poly methyl methacrylate (PMMA) has been investigated by solution viscometric, ultrasonic and differential scanning calorimetric (DSC) methods. From viscosity measurements, Krigbaum and Wall polymer– polymer interaction parameter is evaluated. Ultrasonic velocity and adiabatic compressibilites versus blend composition are plotted, and found to be linear. Tg values are calculated using Gordon–Taylor and Fox equations. The results obtained reveal that CAP forms a miscible blend with PMMA in the entire composition range. Compatibility may be due to the formation of hydrogen bond between the carbonyl group of PMMA and the free hydroxyl group of CAP. Compatibility is further predicted from dielectric measurements.


A novel approach was developed to study the non-isothermal crystallization kinetics of polymers based on the Ozawa equation. The method determines the Avrami exponent, n, using exclusively the data confined to the primary crystallization regime. It was applied to a selection of eleven semicrystalline polymers including some biodegradable polyesters. The differential scanning calorimetry exotherms were obtained from the cooling rates covering 2 to 40 K min-1 . As noted, poly(-caprolactone) and nylon 6,lO resulted in the lowest and highest rr, being equal to 1.5 and 5.1, respectively. The present findings on n were compared with those reported in the literature. Their morphological implications were also discussed


Proton and deuterium spin–lattice relaxation times (T 1), spin–spin relaxation times (T 2), and rotating frame spin–lattice relaxation times (T 1r) and Fluorine T 1 and T 2 were measured as a function of hydration and temperature in hydrated Nafion. The proton and deuterium data display an apparent dynamical transition which we have attributed to a change in the degree of order within the aqueous phase. The temperature at which this transition occurs, T t, is a function of the level of hydration, increasing for decreasing hydration. Above T t, the relaxation processes are similar to those observed in bulk water.


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У багатьох виникає питання: хто такі інженери? Інженер (франц. Ingénieur) - фахівець з вищою технічною освітою. Спочатку інженерами називали людей, які керували військовими машинами. Поняття громадський інженер з'явилося в XVI столітті в Голландії, застосовано до сфери будівництва мостів і доріг, потім інженери з'явилися в Англії, а потім в інших країнах.

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Як стати інженером?

Кожна людина в процесі свідомого життя стикається з проблемою вибору професії. Найбільш актуальною ця проблема є для учнів старших класів – випускників, які добровільно або примусово здають шкільні іспити та зовнішнє незалежне оцінювання, за результатами чого приймають участь в конкурсному відборі на навчання у ВНЗ. Щоб обрана професія не стала важким випробовуванням, потрібно ще у шкільні роки зважити всі «за» і «проти», оцінити свої здібності, схильності, можливості.