Search results for "Condensation polymer"
showing 10 items of 70 documents
Die kationische ɛ-caprolactam-polymerisation. IV. Isolierung und strukturermittlung der oligomeren als beitrag zur aufklärung des polymerisationsmech…
1966
Molekulareinheitliche Oligomere von Polykondensations- und Polyadditionsreaktionen konnen zur Aufklarung von Struktur und Bildungsmechanismus der Polymeren dienen. Auf diesem Wege wird der fruher vorgeschlagene Mechanismus der kationischen Lactampolymerisation mit wasserfreien Sauren erhartet, der in einer Acylierung des Lactams durch Lactamsalz unter Bildung von Aminoacyllactamsalz und nachfolgendem Kettenwachstum durch Addition weiterer Lactammolekule an die entstandene und immer wieder neu gebildete Ammonium-Endgruppe besteht. Dazu werden aus Caprolactam und Chlorwasserstoff als Initiator unter geeigneten Bedingungen Oligomerengemische gewonnen und elektrophoretisch aufgetrennt. Mikropra…
1986
The kinetics of polyamidation was investigated for the reaction of diphenyl terephthalate as activated diester with trimethylhexamethylenediamine (1 : 1 mixture of 2,2,4- and 2,4,4-trimethyl isomers) in dimethyl sulfoxide. The good solubility of the resulting polyamide (Trogamid®(poly(iminoterephthaloylimino-x,y,z-trimethylhexamethylene))) assured a reaction in which all reactants, especially the polyamide, were soluble. The conversion was followed by analysis of the phenol set free and by measuring the number-average degree of polymerization Pn of the polyamide. The reaction obeyed an overall second order with the principle of equal reactivity of functional groups fulfilled for Pn ≿ 16. De…
1986
The aminolysis of diphenyl terephthalate by means of hexylamine was studied in dimethyl sulfoxide as a model reaction for polyamidation. The kinetic analysis showed that the two ester groups of the diphenyl ester do not react independently. Furthermore, the reaction of the first ester group was of mixed second and third order, while the reaction of the second ester group contained only a second order term. The rate constants found were used to determine the Arrhenius activation parameters.
Characterization of melt-polymerized polycarbonate: preparative fractionation, branching distribution and simulation
2001
Melt-polymerized bisphenol-A polycarbonate materials characterized by a low degree of branching were fractionated according to molecular weight by the continuous polymer fractionation (CPF) method. The distribution of two types of end-groups and in-chain salicylate moieties arising from thermal rearrangement reactions were assessed across the molecular weight distribution by analysis of the fractions. Experimentally determined branching densities of the fractions agreed well with a molecular simulation based on a random sampling polycondensation model. Both simulation and experiments showed that the branching density increases with molecular weight in the experimentally accessible range. (C…
Oligo(phenylenevinylene)s with reactive side chains: amine- and amide-bound alkoxysilanes
2002
Strongly luminescent oligo(phenylenevinylene) chromophores with monodisperse chain lengths are connected via short spacers containing a secondary amine or amide with di- and tri-ethoxysilane groups. The alkoxysilanes can be hydrolysed and condensed to cyclic and linear oligomers with high film forming capability and are also interesting functional units for hybrid materials for electro-optical applications. The luminescence properties in the solid state are influenced by hydrogen bonding of the amides resulting in strong hypsochromic shifts. The synthesis of the title compounds, their oligomerisation and the electronic spectra in the solution and solid state are presented.
Die polykondensation des p-kresoldialkohols
1952
Die Polykondensation (Hartung) des p-Kresoldialkohols, die in Platin- oder Silbergeraten ausgefuhrt wird, zeigt ubereinstimmenden Verlauf und ist abhangig von der Reinheit des p-Kresoldialkohols. Die Geschwindigkeit der Kondensation ist verschieden unter Luft und Stickstoff. Ebenso zeigt das Volumen der Schmelze bzw. deren Schichthohe einen Einflus auf die Hartungsgeschwindigkeit. Verfolgt man die Kondensation durch den Gewichtsverlust (in Verbindung mit Formaldehydbestimmungen), so ist die Trocknung der Kondensate besonders zu beachten; der Trocknungsverlust nach der Kondensation kann den Gewichtsverlust unmittelbar nach der Hartung erreichen. Bei Einhalten der angegebenen Kondensationsbed…
Torque rheometry investigation of model transreactions involving condensation polymers: I. Polyesters
2005
The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque-rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water-releasing substance …
Synthesis, characterization and fine-tuning of bimodal poly(organosiloxane) nanoparticles
2010
Abstract The acid catalyzed sol–gel type synthesis of polyorganosiloxane core-shell nanoparticles with removable PDMS core in aqueous dispersion leads to the inherent formation of a bimodal size distribution with smaller spheres having approximately 26 nm radii and larger nanoparticles with 60 nm in radius. The origin of the self-organized bimodality is investigated and finally attributed to a combination of stabilization of the growing particles due to i) a miniemulsion-type stabilization by the ultrahydrophobe PDMS and ii) by surface co-stabilization by the employed surfactant. The significant influence of temperature, pH, stirrer speed and amount of the surfactant on the particle sizes a…
Long-Chain Branched Poly(Lactide)s Based on Polycondensation of AB2 -type Macromonomers
2012
A series of long-chain branched poly(d-/l-lactide)s is synthesized in a two-step protocol by (1) ring-opening polymerization of lactide and (2) subsequent condensation of the preformed AB2 macromonomers promoted by different coupling reagents. The linear AB2 macromonomers are prepared by Sn(Oct)2-catalyzed ROP of D- and L-lactide with 2,2-bis(hydroxymethyl)butyric acid (BHB) as an initiator. Optimization of the polymerization conditions allows for the preparation of well-defined macromonomers (Mw/Mn = 1.09–1.30) with adjustable molecular weights (760–7200 g mol−1). The two-step approach of the synthesis comprises as well the coupling of these AB2 macromonomers and hence allows precise contr…
On the use of PET-LCP copolymers as compatibilizers for PET/LCP blends
1996
Copolyesters of poly[ethylene terephthalate) (PET) with a liquid crystalline polymer (LCP), SBH 1:1:2, have been synthesized by the polycondensation, carried out in the melt at temperatures up to 300 degrees C of sebacic acid (S), 4,4'-dihydroxybiphenyl (B), and 4-hydroxybenzoic acid (H) in the presence of PET. The PET-SBH copolyesters have been characterized by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, etc., and the relationships between properties and preparation conditions are discussed. The copolyesters show a biphasic nature, which is more evident for the products synthesized with a thermal profile comprising relatively lower temperatures (220-…