Browsing by Author "Mateva R."

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    Anionic polymerization of lactams in presence of activating and alloying additives
    (1995-01-01) Mateva R.; Delev O.
    The polymerization of cyclic lactams (ε-caprolactam and ω-dodecalactam) in the presence of anionic initiator and new activators (modifying additives) was studied. The compounds used as modifying additives have the following structures:The effects of the activators on the rate of polymerization, conversion, molecular weight, content of olygomer products, thermal stability were established. The polydispersity of the polyamides obtained in the presence of different activators were investigated. © 1995, The Society of Polymer Science, Japan. All rights reserved.
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    Application of the quantitative IR analysis of copolymers of trioxane
    (1997-01-01) Sirashki G.; Glavchev I.; Mateva R.
    The copolymers of trioxane and 5 to 50% phenyl-or n-butyl glycidyl ethers were investigated with elemental anlysis and IR spectroscopy. Using as an internal standard the methylene absorbance at 1470 sm-1 and the absorbance of C-O-C groups at 900, 930, 1100 and 1240 sm-1, it was determined that the absorbance at 1100 sm-1 is available for quantitative IR analysis of copolymers of trioxane and glycidyl ethers. © 1996 Elsevier Science Ltd.
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    Controlled synthesis of AB2 amphiphilic triarm star-shaped block copolymers by ring-opening polymerization
    (2009-12-01) Petrova S.; Riva R.; Jérôme C.; Lecomte P.; Mateva R.
    This paper describes the synthesis of a novel amphiphilic AB2 triarm star-shaped copolymer with A = non-toxic and biocompatible hydrophilic poly(ethylene oxide) (PEO) and B = biodegradable and hydrophobic poly(ε-caprolactone) (PCL). A series of AB2 triarm star-shaped copolymers with different molecular-weights for the PCL block were successfully synthesized by a three-step procedure. α-Methoxy-ω-epoxy-poly(ethylene oxide) (PEO-epoxide) was first synthesized by the nucleophilic substitution of α-methoxy-ω-hydroxy-poly(ethylene oxide) (MPEO) on epichlorohydrin. In a second step, the α-methoxy-ω,ω′-dihydroxy-poly(ethylene oxide) (PEO(OH)2) macroinitiator was prepared by the selective hydrolysis of the ω-epoxy end-group of the PEO-epoxide chain. Finally, PEO(OH)2 was used as a macroinitiator for the ring-opening polymerization (ROP) of ε-caprolactone (εCL) catalyzed by tin octoaote (Sn(Oct)2). PEO-epoxide, PEO(OH)2 and the AB2 triarm star-shaped copolymers were assessed by 1H NMR spectroscopy, size exclusion chromatography (SEC) and MALDI-TOF. The behavior of the AB2 triarm star-shaped copolymer in aqueous solution was studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). © 2009.
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    In-situ preparation of polyamide-6/polypropylene glycol copolymers with mineral fillers
    (2014-01-01) Krastev P.; Mateva R.
    Polyamide-6 /Polypropylene glycol (PPG) copolymers were synthesized via anionic polymerization of e-caprolactam in the presence of inorganic additives - graphite and boron carbide using isophorone diisocyanate end functionalized PPG prepared in-situ as a macroactivator. Sodium caprolactam was used as an initiator. The influence of the graphite and boron carbide fillers on the degree of conversion was investigated. The copolymers obtained were characterized by 1 H NMR and FTIR spectroscopies. The charpy impact strength of the composites was evaluated.
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    Study of multiblock polyamide-6/Poly-(isoprene) copolymers by positron annihilation spectroscopy
    (2008-11-10) Bryaskova R.; Mateva R.; Djourelov N.; Krasteva M.
    Positron annihilation lifetime spectroscopy (PALS) has been used to determine the free volume in multiblock polyamide-6/poly-(isoprene) copolymers (PA-6/PI), synthesized via activated anionic bulk copolymerization. The diisocyanate functionalized telechelic PI, blocked with caprolactam (CL) has been used as a commoner and an activator at the same time. The elastic PI block incorporated into the main chain of PA-6 affects the amorphous and crystal phase of the copolymer leading to changing in degree of crystallinity. The positron annihilation lifetime spectroscopy (PAL) and Doppler broadening of annihilation line (DBAL) technique in a set of pure PA-6 and PA-6/PI copolymers with two different compositions have been applied and evaluation of the size of free-volume holes (pores), localized mainly in the disordered regions of the PA-6/PI copolymer by measuring the o-Ps lifetime (τ3) and o-Ps intensity (I3) has been performed. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2008.