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The large deformation stress–strain behavior of thermoplastic–elastomeric polyurethanes and elastomeric-thermoset polyureas is strongly dependent on strain rate. Their mechanical behavior at very high strain rates is of particular interest due to their role as a protective coating on structures to enhance structural survivability during high rate loading events. Here we report on the uniaxial compression...
We report a high-shear processing technology that allows the homogenous dispersion of unmodified multiwalled carbon nanotubes (UMWNTs) in a thermoplastic elastomer, poly(styrene-b-butadiene-co-butylene-b-styrene) (SBBS). We demonstrated that the dispersion of UMWNTs in a polymer matrix depends greatly on the shear stress exerted during melt processing. Mechanical tests showed that the tensile modulus,...
Model calculations were performed to investigate the sensitivity of zero-shear melt viscosity (η 0 or Eta0) on the molecular weight (MW) polydispersity of linear polymers. Simulated MW distributions (MWD) were generated with the generalized exponential (GEX) distribution function for various levels of polydispersity M w /M n and M z /M w . For linear entangled...
Micelles have been prepared by mixing poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymers and poly(acrylic acid) (PAA) homopolymers in organic solvents. Complexation via hydrogen bonding occurs between the P4VP and PAA blocks. Further aggregation of the accordingly formed complexes results in micelles stabilized by a corona of PS blocks. The influence of the relative lengths of the different...
A number of urethane acrylate nano- and micro-composites have been developed using both ion exchange and silane grafting chemistry. The organically modified clays which were used contained either methacrylate or acrylate functionalities which were capable of reacting with the acrylate groups in the urethane acrylate matrix. [2-(Acryloyloxy)ethyl]trimethyl-ammonium ion (AOETMA) or [2-(methacryloyloxy)ethyl]trimethylammonium...
Structural and elastic properties of non-charged polymers of stiffness ranging from flexible to rigid chains are computed by Monte Carlo simulations. A discrete wormlike chain (WLC) model with self-interacting units is applied to chains of intermediate lengths of interest in the AFM measurements. Variations of the persistence length and mean chain dimensions with bending stiffness are presented. The...
Aromatic polyamide particles were prepared by reacting m-phthalyl chloride and 4,4′-diaminodiphenyl ether in a dioxane solution with high water content using a precipitation polymerization method. These nanoscale particles were spherical with a narrow size distribution. The morphologies and characteristic features of the polyamide products obtained depended strongly on the water content of this polymerization...
A copolyester was characterized to have 91mol% trimethylene terephthalate unit and 9mol% ethylene terephthalate unit in a random sequence by using 13 C NMR. Differential scanning calorimeter (DSC) was used to investigate the isothermal crystallization kinetics in the temperature range (T c ) from 180 to 207°C. The melting behavior after isothermal crystallization was studied by using...
The paper presents the mechanism of the polymerization of ɛ-caprolactone with the use of Zr(Acac) 4 . At the first stage of the initiation of the polymerization, a reaction consisting of proton transfer from caprolactone to acetylacetonate ligand and then ligand exchange reaction with release of free acetylacetone (HAcac) occur. Complex 1, arisen as a product of this reaction, is the actual...
The morphology change of an asymmetric polystyrene-block-poly(2-vinyl pyridine) (PS-b-PVP) diblock copolymer micellar film was investigated during solvent vapor annealing in chloroform. Initially, smaller islands in nanometer-length scale form at the film surface. Further annealing results in the growth of the islands composed of the PS-b-PVP cylinders above the bottom brush layer. For comparison,...
Calorimetric experiments at cooling rates comparable to those during injection molding, as an example, are needed to study phase transitions under conditions relevant for processing. Ultra fast scanning calorimetry is a technique which provides a means to analyze the materials of interest under rapid cooling conditions and it is a promising technique by which the crystallization behavior of composite...
A novel calcium complex, [(DAIP) 2 Ca] 2 (where DAIP-H=2-[(2-dimethylamino-ethylimino)methyl]phenol), is prepared in a one flask reaction by condensation of Ca(OMe) 2 with DAIP-H in toluene/THF. Experimental results show that in the presence of various alcohols, [(DAIP) 2 Ca] 2 efficiently initiates the ring-opening polymerization of l-lactide in a controlled...
A novel sulfonated diamine monomer, 1,4-bis(4-aminophenoxy)-naphthyl-2,7-disulfonic acid (BAPNDS), was synthesized. A series of sulfonated polyimide copolymers were prepared from BAPNDS, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and nonsulfonated diamine 4,4′-diaminodiphenyl ether (ODA). Flexible, transparent, and mechanically strong membranes were obtained. The membranes displayed slightly...
This paper investigates the decomposition mechanism and fire performance of high performance epoxy amine resins and laminate systems, using thermogravimetry (TGA), energy dispersive spectroscopy (EDS), cone calorimetry and Fourier transform infra-red spectroscopy (FTIR). Two different, commercially-important epoxy resins, tetraglycidyl methylene dianiline (TGDDM) and diglycidyl ether of bisphenol...
We report herein the synthesis of hydrophilic–hydrophilic AB diblock copolymers of 3-O-methacryloyl-d-galactopyranose (MAGP) with 2-(dimethylamino)ethyl methacrylate (DMAEMA). These materials were obtained from precursor AB diblock copolymers of 3-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose (MAIpGP) and DMAEMA. The well-defined precursor block copolymers were prepared via reversible...
The efficiency of the photoinitiator system composed of safranine and triethanolamine for the polymerization of acrylamide in water was improved by the incorporation of onium salts. The phenylonium salts employed were diphenyliodonium chloride, triphenylsulfonium triflate, tetraphenyphosphonium chloride and tetraphenylarsonium chloride hydrate. Among them, diphenyliodonium presents the highest efficiency,...
A new synthetic procedure was elaborated allowing the preparation of semiaromatic dianhydride. N-Methyl protected 4-chlorophthalic anhydride was nitrated with HNO 3 to produce N-methyl-4-chloro-5-nitrophthalimide (1). The aromatic nucleophilic substitution reaction between 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1-spirobisindane and 1 afforded spirobisindane-linked bis(N-methylphthalimide)...
A mixture of sodium polystyrene sulfonate (NaPSS) and anionic surfactant, sodium dodecyl sulfate (SDS), was used as the emulsifier in the emulsion polymerization of styrene at 60°C. The latexes prepared were stable, bearing the better resistance to the addition of electrolyte, and have the larger values in particle size and the higher polymerization rates than those counterparts prepared using SDS...
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