Showing papers on "Polytetrahydrofuran published in 2008"

Polytetrahydrofuran/Clay Nanocomposites by In Situ Polymerization and Click Chemistry Processes

Abstract: Polytetrahydrofuran (PTHF)/clay nanocomposites were prepared by two routes: in situ cationic ring opening polymerization (CROP) and a method involving "click" chemistry. In the first method, PTHF chains were grown from the surface of the organo-modified montmorillonite clay by CROP of tetrahydrofuran (THF) through the hydroxyl functions of the clay by using trifluoromethanesulfonic anhydride, in the presence of 2,6- di-tert-butylpyridine as proton trap and dichloromethane as solvent. The polymerizations were affected by the clay content ratios. The living characteristics of the polymerization were demonstrated by the semilogarithmic first order kinetic plot. In the second method, CROP of THF has been performed independently to produce alkyne- functionalized PTHF and the obtained polymers were subsequently anchored to azide-modified clay layers by a "click" reaction. The exfoliated polymer/clay nanocomposites obtained by both methods were characterized and compared by X-ray diffraction spectroscopy, thermogravimetric analysis, and transmission electron microscopy. Compared to the virgin polymer, the nanocomposites exhibited improved thermal stabilities regardless of the preparation method. However, the nanocomposites prepared by the "click" chemistry approach appeared to be thermally more stable than those prepared by in situ polymerization. Moreover, the "click" chemistry method also provided better exfoliation.

Synthesis and characterization of organically modified attapulgite/polyurethane nanocomposites

Abstract: Polyurethane (PU) nanocomposites filled with attapulgite (ATT) nanorods were synthesized and characterized with thermal analysis, dynamic mechanical analysis (DMA), and mechanical testing. The formulations were based on 4,4'-methylene bis(phenyl isocyanate) (MDI), polytetrahydrofuran, 1,4-butanediol, and inorganic ATT premodified with MDI. The original and premodified ATT (ATT-OH and ATT-MDI) nanorods were characterized with thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The analysis revealed that 17 wt % MDI was grafted/adsorbed onto the surface of ATT as a result of the modification. Pristine PU and ATT-MDI/PU nanocomposites were characterized with scanning electron microscopy, differential scanning calorimetry, and TGA. The mechanical tests and DMA showed an increase in the storage modulus and Young's modulus with increasing ATT-MDI content. The crystallinity of the hard and soft segments and thermal stability showed enhancements over those of the neat resin.

Adhesive of epoxy resin, toughener and blocked isocyanate polytetrahydrofuran toughener

Abstract: Epoxy adhesive compositions contain an epoxy resin, rubber modification, a toughener and a curing agent. The tougher has capped epoxide-reactive groups, and at least one polytetrahydrofuran block having a mass of 2200-4500 daltons. The selection of toughener in a rubber-modified epoxy-based structural adhesive provides for very good low temperature performance.

Structural Requirements for the Intercalation of Polyether Polyols into Sodium‐Montmorillonite: The Role of Oxyethylene Sequences

Abstract: The structural requirements for the preparation of polyether polyol/Na + -montmorillonite nanocomposites, which are used in polyurethane/NaMMT nanocomposites, were evaluated using X-ray diffraction, thermogravimetric analysis and shear viscosity behavior. Nanocomposites based on homopolyetherols: poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), polytetrahydrofuran (PTHF), block-type copolyetherols and a SAN-grafted polymer polyol were prepared. Intercalation was observed only with oxyethylene (EO) units containing polyetherols. The amount of the intercalated polyetherol ranged from 15 to 30 wt.-%. EO-sequences of 5 F to 6 units proved to be sufficient for intercalation, which suggests a crown-ether type complexation of interlayer cations.

Preparation and evaluation of a linoleic-acid-modified amphiphilic polypeptide copolymer as a carrier for controlled drug release

Abstract: In the present study, we describe the synthesis, characterization and self-assembly of a novel amphiphilic linoleic acid (LA)-modified polypeptide copolymer and its drug release behavior in vitro as well. Initially, an amphiphilic ABA triblock copolymer comprising polytetrahydrofuran (PTHF) as a central hydrophobic block and poly(L-lysine)s as outer hydrophilic blocks was prepared via the ring-opening polymerization of epsilon-benzyloxycarbonyl-L-lysine N-carboxyanhydride with a distal amine-terminated PTHF as a macroinitiator, followed by the removal of the protecting group. The resulting triblock copolymer was then reacted with linoleic acid in the presence of N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCHCl)/N-hydroxysuccinimide (HOSu) to give rise to a target LA-modified polypeptide copolymer. It was found to self-assemble into nanoparticles in water. Its critical aggregation concentration was assessed by fluorescence measurement with N-phenyl-1-naphthylamine employed as a molecular probe. The particle sizes of the aggregates were determined by dynamic light scattering, and the aggregate morphologies were evidenced by transmission electron microscopy measurements. Finally, the drug-loading capacity and release behavior in vitro were investigated by using doxorubicin as a model drug.

Process for producing colorful spandex fiber

Abstract: The invention discloses a preparing method of a polyether type colored spandex fibre in spandex fiber preparing technique domain, which comprises the following steps: 1, providing Polytetrahydrofuran; 2, providing 4, 4'-diphenylmethane diisocyanate; 3, reacting; getting terminated Polytetrahydrofuran; setting the mole ratio of the diisocyanate and the Polytetrahydrofuran at 1.55-2.15; 4, providing amide compound as solvent; mixing; dissolving the terminated Polytetrahydrofuran; forming solution; 5, mixing with enlarged chain agent mixture; forming polyurethane urea solution; 6, pretreating with colorant; collecting colour; dispersing; getting suspension or coloring processor with proper density; 7, adding into polyurethane solution; stirring evenly; getting spandex spinning solution; 8, proceeding air spinning; forming colour spandex. This invention solves the problem of difficult colouration, which product possesses bright colour and high colour stability.

Process for producing polyether type comfortable spandex fibre

Abstract: The invention discloses a preparing method of a new type spandex fibre in spandex preparing technique domain, which comprises the following steps: (1)providing Polytetrahydrofuran; (2)providing 4, 4'-diphenylmethane diisocyanate; (3)reacting; getting terminated Polytetrahydrofuran; setting the mole ratio of the Polytetrahydrofuran and the 4, 4'-diphenylmethane diisocyanate at (1.55-2.15): 1; (4)providing dissolvent; mixing; dissolving the terminated Polytetrahydrofuran; forming solution; (5)mixing the solution and enlargering chain agent mixture; forming polyurethane urea solution; (6)spinning the polyurethane urea solution; forming spandex. This product possesses good hand touch and comfortable wear.

Method for preparing nano TiO2 polyester ether elastic fiber

Abstract: The invention relates to nanometer TiO2 polyether ester elastic fiber manufacturing method. It includes the following steps: preparing nanometer TiO2/1, 4-butanediol system that replacing the nanometer TiO2 by 1,4-butanediol as dispersion medium and vacuum pumping at 70-80 deg.C; preparing polyether ester elastic body that using dimethyl terephthalate, polytetrahydrofuran ether glycol, 1, 4-butanediol as material, adding 0.1-2.0% mass fraction nanometer TiO2, vacuum pumping at 50-100 deg.C, ester interchange reacting at 180-200 deg.C, condensation polymer reacting for 3-4h at 230-250 deg.C under 80Pa; melt spinning. This technology is simple. In addition, the prepared fiber has even nanometer particle disperse, good elastic recovery, low cost, suits for industrialization production.

Catalyst, its preparation and the polymerization of cyclic ethers over this catalyst

Abstract: The present invention relates to a solid, acid catalyst for the preparation of polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of these polymers by polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer, which has a BET surface area of at least 160 m2/g and an acid center density of at least 0.05 mmol/g for pKa values of from 1 to 6, to a process for preparing it and to a process for the polymerization of cyclic ethers over this catalyst.