1993 рік

Poly(amide sulfonamide)s 1-4 were synthesized by low-temperature solution polycondensation of diamino monomers 5 and 6 with isophthaloyl chloride/terephthaloyl chloride in N,N-dimethylacetamide (DMAc). The polymers were adequately characterized for their properties. Membranes were fabricated from PASA 2 under different casting conditions by varying the casting solution composition, evaporation temperature and evaporation time. The reverse osmosis (RO) tests for these membranes were performed with 1000 ppm aqueous sodium chloride feeds at 20 to 40 kg cm- 2 operating pressure. Membranes showed salt rejections of up to 97.9% at a flux of over 11.9cm per day. The RO performances of the membranes remained unchanged after treatment with dilute acid, alkali and oxidizing agent.

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~-Vinyl-p-xylylene (16) has been shown to be an intermediate in the base-catalysed decomposition of both p-allylbenzyltrimethylammoniumb romide (17) and p-methylcinnamyltrimethylammoniumb romide (19). Cyclic dimers (28) and (29) (EE and ZZ isomers, respectively ) are produced via the conjugatively extended vinyl head h' to head h' and tail to tail bond-forming reactions, which accompany a copolymer formed mainly via the contrasting head (vinyl-substituted head h and h') to tail linking of ct-vinyl-p-xylylene.

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I.r. spectroscopic analysis, in particular by means of the technique of attenuated total reflection, is used to characterize the grafting of polypropylene (PP) films by poly(acrylic acid). A method allowing us to separate the grafted part from that of unmodified PP is also used. Finally, we compare the results obtained when the film to be modified is initially treated or not to eliminate some of the additives present. We show that whatever the case, the grafting always starts from the interface between the PP and the polymerization solvent. Therefore, grafting in all the material can be easily obtained when the additives are extracted

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Isothermal cold crystallization of the thermoplastic polyimide NEW-TPI has been investigated from 300 to 360°C. The fastest crystallization took place at 330°C where the time to maximum exothermic heat flow was 148 s. A single Avrami exponent could be used to describe the bulk crystallization kinetics for degrees of conversion from 0.02 up to 0.95, indicating that most crystallization takes place at the growth front by a single mechanism, nearly up to the completion of crystallization. The Avrami exponent is 3.5 for T~ < 330°C, and decreases as T c increases. A regime II to III transition is indicated by a slope change seen in In(I/tl/2)+U/R(T-T,) vs. 1/TATf These results indicate that NEW-TPI cold crystallization can be modelled according to heterogeneous nucleation and three-dimensional crystal growth. From T m vs. Tc analysis, the infinite-crystal melting point of NEW-TPI is estimated to be 400°C. With regard to the glass transition, Tg was affected by cold crystallization in a systematic but minor way. The heat-capacity increment of semicrystalline NEW-TPI at Tg shows a small negative deviation from that predicted on the basis of the degree of crystallinity. The absence of secondary crystallization processes has been used to explain the different glass transition behaviour and small negative heat-capacity deviation in NEW-TPI. Real-time small-angle X-ray scattering (SAXS) was used to monitor the structure change as a function of cold crystallization time at 300°C. Systematic change of long period, lamellar thickness, invariant and volume fraction of crystallinity were obtained from the one-dimensional electron density correlation function analysis. At T~=300°C, lamellar thickness as a function of t~ ranges from 37 to 52 ~, or about 1.5 2.0 times the monomer repeat unit. The thickness of the interphase region was determined from SAXS to be about 17 ,~ independent of cold crystallization time at 300°C.

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~-Phenyl-p-xylyene (7) has been shown to be an intermediate in the base-catalysed decomposition of both p-benzylbenzyltrimethylammonium bromide (11) and p-methylbenzhydryltrimethylammonium bromide (12). All the possible cyclic trimers of unsymmetrical linking are formed (i.e. phenyl-substituted head h to h and tail to tail links), which accompany a polymer formed mainly via the contrasting head to tail linking of ct-phenyl-p-xylylene.

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A series of random copolymers of 4-vinylphenol with n-alkyl methacrylates were synthesized by free-radical copolymerization of 4-t-butyldimethylsilyloxystyrene and the corresponding alkyl methacrylates, followed by selective removal of the t-butyldimethylsilyl protective group. Copolymerizations were performed in benzene at 60°C using azobisisobutyronitrile as an initiator and reactivity ratios were determined using the Kelen-TiidSs method. Removal of the protective group was effected by tetrabutylammonium fluoride in tetrahydrofuran at ambient temperature. An infra-red spectroscopic characterization of these copolymers is reported.

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The morphology and mechanical properties of the mouldings of a poly(styrene-block-butadiene-blockstyrene) triblock copolymer (KR05, Phillips Petroleum Co.) were examined. All the mouldings exhibit lamellar morphology and their mechanical properties depended on the lamellar orientation. KR05 with oriented lamellae shows excellent Izod impact strength and large elongation since under tensile stress the lamellae shear yield extensively with dominant expansion and cavitation of the polybutadiene lamellae. That with wavy lamellae shows enhanced rigidity and heat resistance since the lamellae also shear yield but offer more resistance against the deformation because of the close and complicated networks of the polybutadiene phase with the rigid polystyrene phase. Stereoscopic structural examination of the mouldings revealed that the appreciable mechanical anisotropy results from the anisotropy of the microdomain structure formed on cooling the melt.

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A new series of liquid crystalline (LC) monomers based on an unsymmetrically disubstituted cyanostilbene containing hydroxy- and carboxylic acid groups has been synthesized and characterized. The monomers could be polymerized in the presence of N,N-dicyclohexylcarbodiimide and 4-pyrrolidinopyridine to give a new class of main-chain LC polymers which may have potential applications in the field of non-linear optics.

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A multistep synthetic route for the preparation of a series of poly(oxy-l,4-phenyleneoxycarbonyl-l,4- phenyleneoxypolymethylene)s having a varying length of the polymethylene spacer from the di- to the hexamethylene group is reported. The polymers prepared were characterized particularly for their liquid crystalline properties by differential scanning calorimetry, wide-angle X-ray diffractometry and observation of their textures on a polarizing optical microscope. All the polymers, with the exception of the trimethylene polymer, formed the nematic phase in melt. They exhibited the well known odd-even effect at melting temperature as well as at isotropization temperature.

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a-(3-Aminopropyl-l-amino)polystyrene (~-amino-PS) was melt-blended with styrene/maleic anhydride copolymers (SMA) containing 28 wt% maleic anhydride groups. The terminal primary amino group can react with the maleic anhydride monomer units in SMA, forming imides. The resulting product turned out to be an efficient emulsifier for SMA blends with poly(phenylene oxide) (PPO). At constant weight fraction of added ~-amino-PS, the size of the dispersed PPO particles decreased with decreasing molar mass, i.e. increasing mole fraction, of the ~-amino-PS. In a second series of experiments, ct-amino-PS with ]~n > ]~entangl .... t, was used to compatibilize SMA/PPO blends which also contained poly(acrylonitrileco- butadiene-co-styrene) and some poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer. Although, in this case, it was not possible to detect major changes in the phase texture or morphology, it could be shown that the addition of ct-amino-PS improved the impact strength significantly. For comparison, blends were also prepared with unmodified PS of a similar M,. No corresponding improvement of the mechanical properties was observed in this case.

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