Showing papers on "Polytetrahydrofuran published in 2003"

Binary blends of polyethers with fatty acids: A thermal characterization of the phase transitions

Abstract: A series of binary blends of poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and polytetrahydrofuran (PTHF), characterized by similar average molecular weights, with selected fatty acids (capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid) were prepared by melt mixing. Differential scanning calorimetry was applied to characterize the phase transitions of melting and crystallization, and a synergistic effect was found to occur for PEO/fatty acid blends, as evidenced by the values of the enthalpy of the phase transition. This effect was probably due to hydrogen bonding between PEO and the fatty (carboxylic) acids, which facilitated the formation of crystalline structures; an analysis of IR spectroscopy data showed a shift in the absorption bands of OH groups. The morphology development of the PEO/carboxylic acid blends, as observed with polarizing light microscopy, could be described as spherulitic growth with spontaneous selection of the lamellar thickness. The textures of the individual fibrils, consisting of stacks of several tens of lamellae corresponding to PPO and PTHF, were less regular than the texture of PEO and showed large macroscopic heterogeneity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 861–870, 2003

Segmented polymer networks containing amino‐dendrimers

Abstract: Polymer networks in which poly(propylene imine) dendrimers (Astramol™) are connected to each other by linear polytetrahydrofuran (polyTHF) segments, were prepared by two methods The first method was a one-step procedure in which bifunctionally living polyTHF, obtained by initiation of the THF polymerization with trifluoromethane sulfonic anhydride (triflic anhydride), was reacted with an amino-dendrimer This reaction was very fast but did not allow formation of the end products The second method was a two-step procedure In a first step, living polyTHF, prepared with acryloyloxybutyl triflate as initiator, was grafted on an amino-dendrimer, to form a star-like, acrylate-terminated polyTHF multi-macromonomer with the dendrimer as core In a second step, networks were obtained by Michael addition between the acrylate end-groups and unreacted amino-groups of the dendrimer This cross-linking reaction occurred spontaneously upon heating of the solution of the multi-macromonomer with gelation times varying from a few minutes to a few hours, depending on the temperature and the composition of the prepolymers With this method it was possible to prepare networks in the form of coatings or films © 2003 Society of Chemical Industry

Aqueous polyurethane dispersion comprising polytetrahydrofuran polyol

Abstract: An aqueous polyurethane dispersion comprises a polyurethane obtained by the reaction of: (A) an isocyanate-terminated prepolymer formed from components which comprise (i) 10 to 25 wt% of polyisocyanate(s); (ii) 40 to 80 wt% of polytetrahydrofuran polyol(s); (iii) 0 to 5 wt% of polyol(s) containing ionic or potentially ionic water-dispersing groups having two or more isocyanate-reactive groups; (iv) 0 to 50 wt% of a component(s) not comprised by (i), (ii) or (iii); where (i), (ii), (iii) and (iv) add up to 100 wt%; and (B) an active-hydrogen chain extending compound. Also claimed are polyurethane dispersions wherein the polyisocyanates comprise a mixture of hexamethylene diisocyanate and isophorone diisocyanate. An adhesive composition according to the formulation is also claimed. The dispersion may be used to form a glove by a dipping process.

Swelling and drying kinetics of polytetrahydrofuran and polytetrahydrofuran–poly (methyl methacrylate) gels: A photon transmission study

Abstract: A bifunctional polytetrahydrofuran (PTHF) macromonomer was synthesized by termination of the living polymerization of tetrahydrofuran (THF) initiated by triflic anhydride and the subsequent termination by sodium methacrylate. The PTHF macromonomer thus prepared was polymerized and copolymerized with methyl methacrylate (MMA) by free-radical polymerization to yield a network and a segmented network of PTHF, both being homogeneous, respectively. These PTHF and PTHF–PMMA gels were used for swelling experiments in chloroform and chloroform vapor. Drying processes were monitored after removing the gels from the solvent and solvent vapor. Photon transmission from PTHF and PTHF–PMMA gels was monitored during swelling and drying processes using a UV-visible (UVV) spectrophotometer. Transmitted light intensities, Itr, from these gels increased when they were immersed in chloroform and/or subjected to its vapor. The increase in Itr was attributed to the homogeneous lattice structure of PTHF and PTHF–PMMA gels which appeared during swelling. The increase in Itr was modeled using the Li–Tanaka equation from which time constants, τ1, and cooperative diffusion coefficients, DC, were determined. A decrease in Itr after removing choloform and/or its vapor from the cell was observed and attributed to the decrease in homogeneity of lattice structures during drying of the corresponding gels. Time constants, τ2, for the drying processes were also determined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 632–640, 2003

Comparative study of liquid-crystalline ordering in a monomer, linear polymer, and graft copolymer by the photon transmission technique

Abstract: The photon transmission technique was used to study the phase transitions of a liquid crystalline acrylate monomer, 6-(4-cyanobiphenyl-4′oxy)hexyl acrylate (LC6), its homopolymer (PLC6) and its graft copolymer (GLC6) with polytetrahydrofuran grafts. The phase transitions were also confirmed by DSC and polarizing microscopy. We observed the phase transition sequence isotropic–nematic–smectic A–smectic C in the LC6 monomer. In PLC6 and GLC6 polymers, the nematic and smectic A phases appear dominant. The apparent nematic–smectic A transition is of first order in PLC6 and of second order in GLC6, with the transition temperature remaining the same. The effects of quenched random constraints introduced in GLC6 are consistent with the theory of quenched random interactions. The critical exponents were also evaluated.

Catalyst, method for producing the same and method for the polymerisation of cyclic ethers on said catalyst

Abstract: The invention relates to a solid, acid catalyst for the production of polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of said polymers by the polymerisation of tetrahydrofuran in the presence of at least one telogen and/or comonomer. Said catalyst has a BET surface area of at least 160 m2/g and an acid site density of at least 0.05 mmol/g for pKs values of between 1 and 6. The invention also relates to a method for producing the catalyst and to a method for the polymerisation of cyclic ethers on said catalyst.

Thermoplastically processable polyurethane molding material

Abstract: A thermoplastically processable polyurethane molding material which is composed of a blend of at least two thermoplastic polyurethane, with at least 5 percent by weight, as a component A, being composed of a thermoplastic polyurethane which is obtained by reacting one or a plurality of aliphatic polyols which have a molecular weight of 800 to 4000 g/mol and a hydroxyl number of 20 to 235 and which are selected from the group of polyadipates, polycaprolactones, polycarbonates, polytetrahydrofurans and corresponding copolymers or mixtures thereof with 1,6-hexamethylene diisocyanate and the chain-extending agent 1,6-hexanediol in an equivalent ratio of the 1,6-hexamethylene diisocyanate to the polyol of 1.5:1 to 14.0:1, the NCO index formed from the quotient, which is multiplied by 100, of the equivalent ratios of isocyanate groups to the sum of the hydroxyl groups of polyol and chain-extending agent lying within a range of 96 to 105, and 100 percent by weight of the rest, as a component B, being composed of one or a plurality of further thermoplastic polyurethane which is obtained by reacting one or a plurality of aliphatic polyols which have a molecular weight of 800 to 4000 g/mol and a hydroxyl number of 20 to 235 and which are selected from the group of polyadipates, polycaprolactones, polycarbonates, polytetrahydrofurans and corresponding copolymers or mixtures thereof with the diisocyanates: 1,6-hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate and a chain-extending agent selected from the group of 1,4-butanediol, 1,5 pentanediol, 1,4-cyclohexanediol, bis(hydroxymethyl)cyclohexane, bis(hydroxyethyl)hydroquinone, polycaprolactone having a number average molecular weight of 350 to 600 g/mol and polytetrahydrofuran having a number average molecular weight of 200 to 600 g/mol in an equivalent ratio of the diisocyanate to the polyol of 1.5:1 to 14.0:1, the NCO index formed from the quotient, which is multiplied by 100, of the equivalent ratios of isocyanate groups to the sum of the hydroxyl groups of polyol and chain-extending agent lying within a range of 96 to 105.

Method for producing monoesters and diesters of polytetrahydrofuran and of tetrahydrofuran copolymers

Abstract: The present invention provides a process for preparing mono- or diesters of polytetrahydrofuran or of tetrahydrofuran copolymers by polymerizing tetrahydrofuran in the presence of at least one telogen and/or of a comonomer over an acidic catalyst, wherein the polymerization reactor is started up using a mixture of polytetrahydrofuran, the mono- or diesters of polytetrahydrofuran and/or of the THF copolymers, tetrahydrofuran, any comonomer and at least one carboxylic acid and/or one carboxylic anhydride.

Method for the polymerization of cyclic ethers

Abstract: The invention relates to a method for producing polytetrahydrofuran, polytetrahydrofuran copolymer, polytetrahydrofuran diester, or polytetrahydrofuran monoester by polymerizing tetrahydrofuran in the presence of at least one telogen and/or comonomer and an acid heterogeneous catalyst based on activated layered silicates or mixed metal oxides in a fluidized bed.

Method for the production of polytetrahydrofuran with a reduced cyclical oligomeric ether content

Abstract: The invention relates to a method for producing polytetrahydrofuran (PTHF) or tetrahydrofuran (THF) copolymers having an average molecular weight of 650 to 6000 and a cyclical oligomeric ether content of less than 1 percent by weight by means of a treatment with a solvent. The inventive method is characterized by the following steps: a) PTHF or THF copolymers is/are extracted in one or several steps with an aliphatic, linear or branched, cycloaliphatic or olefinic hydrocarbon containing 1 to 15 hydrocarbon atoms, mixtures of said hydrocarbons, or mixtures containing at least 50 percent by weight of said hydrocarbons at temperatures ranging from 20 to 120° C; b) the PTHF phase or THF copolymer phase is separated from the hydrocarbon phase; c) the PTHF phase or THF copolymer phase is largely liberated of hydrocarbon; d) the hydrocarbons are separated from the hydrocarbon phase obtained in step b) by means of distillation; and e) the mixture of cyclical oligomeric ethers and linear PTHF oligomers or oligomeric THF copolymers resulting from step d) is cat-cracked back to THF, and THF is optionally returned to polymerization.

Cross-linked polyurethanes consisting of polytetrahydrofuran

Abstract: The invention relates to a cross-linked polyurethane consisting of: A) at least one polytetrahydrofuran of general formula (I), in which n = 4 to 40; B) at least one compound that contains more than 2 active hydrogen atoms per molecule; C) at least one compound that contains at least 2 active hydrogen atoms per molecule and at least one ionogenic and/or ionic group per molecule, whereby said groups are anionogenic, anionic, cationogenic or cationic groups; D) at least one diisocyanate; E) optionally one compound that differs from B) and C), contains at least two active hydrogen atoms and has a molecular weight of between 60 and 5,000; or the salts thereof.

Method for manufacturing cyan-based catalyst using zinc chloride, hexacyanocobaltate and organic complexing agent

Abstract: PURPOSE: To provide a catalyst manufacturing method that reduces activation time of catalyst during epoxy reaction by finely controlling particle size of catalyst, reduces manufacturing time including separation time and drying time of precipitates, organic complex and washing solution produced by reaction of zinc chloride and hexacyanocobaltate and improves yield of catalyst manufactured. CONSTITUTION: In a method for manufacturing a double metal cyan-based compound catalyst used in the epoxy based polymer manufacturing process, the method for manufacturing a high activated double metal cyan-based catalyst is characterized in that the high activated double metal cyan-based catalyst is manufactured by using zinc chloride, hexacyanocobaltate and organic complexing agent, and drying and filtrating a slurry, wherein the dry filtration is spraying a solution with a sparge into dryfilter, and wherein the complexing agent is one or more selected from ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, polypropylene glycol, polyethylene glycol, and polytetrahydrofuran.

Functional segmented polymer networks based on polytetrahydrofuran and poly(vinylbenzyl chloride)

Abstract: Abstract Functional segmented polymer networks (FSPNs) were synthesised via free radical initiated copolymerisation of polytetrahydrofuran (PTHF) bis-macromonomers with vinylbenzyl chloride (VBCl). The purpose of this work was to create FSPNs, providing supports with a functional group that can be substituted and may serve to immobilise other reagents such as catalysts. After the preparation and detailed characterisation of several PTHF bis-macromonomers, FSPNs were prepared with varying molecular weight of the PTHF chain and varying PTHF/ PVBCl ratio. Measurements of the soluble fraction and elemental analyses demonstrated that FSPNs with a wide composition range could be prepared. From dynamic-mechanical and thermal analyses, it could be concluded that most FSPNs showed some degree of compatibility and complete absence of crystallinity. The mechanical properties of the FSPNs are directly related to their composition. The degree of substitution of all networks is close to quantitative.

Binders for inorganic powders for producing shaped metallic and ceramic bodies

Abstract: A binder B for inorganic powders comprises a mixture of b1 from 80 to 995% by weight of a polyoxymethylene homopolymer or copolymer B1 and b2 from 05 to 20% by weight of a polymer system B2 which is not miscible with B1 and comprises b21 from 5 to 100% by weight of polytetrahydrofuran B21 and b22 from 0 to 95% by weight of at least one polymer B22 of C2-8-olefins, vinylaromatic monomers, vinyl esters of aliphatic C1-8-carboxylic acids, vinyl C1-8-alkyl ethers or C1-12-alkyl (meth)acrylates

Method for producing polytetrahydrofurane having a low color indices

Abstract: The invention provides a process for preparing polytetrahydrofuran, tetrahydrofuran copolymers, their monoesters or diesters and the monoesters or diesters of polytetrahydrofuran having a low color number in the presence of a catalyst, which comprises converting crude tetrahydrofuran which has been prepared in a manner per se into pure tetrahydrofuran by distillation, subsequently subjecting the latter to essentially complete hydrogenation and using the high-purity tetrahydrofuran obtained in this way for the polymerization directly after its preparation.

Method for reducing the portion of cyclical oligomeric ethers in polytetrahydrofuran or tetrahydrofuran copolymers

Abstract: Disclosed is a method for reducing the portion of cyclical oligomeric ethers contained in polytetrahydrofuran (PTHF) or tetrahydrofuran (THF) copolymers, according to which the PTHF or the THF copolymers is/are extracted in one or several steps with a aliphatic, linear, branched, cycloaliphatic, or olefinic hydrocarbon containing 4 to 15 C atoms, mixtures of said hydrocarbons, or mixtures containing at least 50 percent by weight of said hydrocarbons at temperatures ranging from 30 to 200 DEG C, and the PTHF phase or THF copolymer phase is separated from the hydrocarbon phase. The extraction process takes place in a column comprising a central stirrer which extends across several superimposed stirring areas. The ratio between the circumferential speed cubed of the stirrer and the height of the stirrer is greater than 0.5 m2/s3.

Polymeric formula with high adhesive qualities, particularly for the manufacture of soles for footwear, and soles for footwear made with this formula.

Abstract: Polymeric formula with high adhesive qualities, particularly for the manufacture of soles for footwear, and soles for footwear made with this formula which comprises a polyol composition, which in turn includes a diol (for example 1,4-butanediol) and a linear polyether of low molecular weight (preferably polytetrahydrofuran), and a prepolymer of low molecular weight with a linear polyether chain and containing predetermined active isocyanate (NCO) groups: in particular, this prepolymer is the product of a reaction between a polytetrahydrofuran of a molecular weight of 1000 and diphenylmethane diisocyanate, (MDI).