Morphology, structure, and properties of in situ compatibilized linear low-density polyethylene/polystyrene and linear low-density polyethylene/high-impact polystyrene blends

Blends of linear low-density polyethylene (LLDPE) with polystyrene (PS) and blends of LLDPE with high-impact polystyrene (HIPS) were prepared through a reactive extrusion method. For increased compatibility of the two blending components, a Lewis acid catalyst, aluminum chloride (AlCl3), was adopted to initiate the Friedel-Crafts alkylation reaction between the blending components. Spectra data from Raman spectra of the LLDPE/PS/AlCl3 blends extracted with tetrahydrofuran verified that LLDPE segments were grafted to the para position of the benzene rings of PS, and this confirmed the graft structure of the Friedel-Crafts reaction between the polyolefin and PS. Because the in situ generated LLDPE-g-PS and LLDPE-g-HIPS copolymers acted as compatibilizers in the relative blending systems, the mechanical properties of the LLDPE/PS and LLDPE/HIPS blending systems were greatly improved. For example, after compatibilization, the Izod impact strength of an LLDPE/PS blend (80/20 w/w) was increased from 88.5 to 401.6 J/m, and its elongation at break increased from 370 to 790%. For an LLDPE/HIPS (60/40 w/w) blend, its Charpy impact strength was increased from 284.2 to 495.8 kJ/m(2). Scanning electron microscopy micrographs showed that the size of the domains decreased from 4-5 to less than 1 mum, depending on the content of added AlCl3.

Synthesis and crystal structure of bis (tert-butyl-cyclopentadienyl)erbium ethoxide, (t-BuCp)(2)ErOEt

The formation of ( t-BuCp)(2)ErOEt was discussed. Its single-crystal structure was determined by X-ray diffraction. The crystal is monoclinic, P2(1)/c space group, a = 1.0191(2), b = 1.6203(5), c = 1.2118(3) nm, beta = 102. 960( 10)degrees, V = 1.9500 (nm(3)), Z = 2, D-c = 1.566 mg . m(-3), R = 0.0450, R-w = 0.1363. The complex is monomeric and solvent-free in the solid state. The erbium ion is coordinated by two tert-butyl-cyclopentadienyl rings and one oxygen atom of ethoxy group to form a seven-coordinated complex.

Syntheses and crystal structures of bis(tetrahydrofurfurylindenyl) lanthanocene chlorides (C4H7OCH2C9H6)(2)LnCl (Ln = Nd, Sm, Dy, Ho, Er, Yb)

Reaction of anhydrous lanthanide trichlorides with tetrahydrofurfuryl indenyl lithium in THF afforded bis(tetrahydrofurfurylindenyl) lanthanocene chlorides complexes (C4H7OCH2C9H6)(2) LnCl, Ln = Nd (1), Sm (2), Dy (3), Ho (4), Er (5), Yb (6). The X-ray crystallographic structures of all the six complexes were determined and these indicate that they are unsolvated nine-coordinate monomeric complexes with a trans arrangement of both the sidearm and indenyl rings in the solid state. They belong to the same crystal system (orthorhombic) and space group (P2(1)2(1)2(1)) with the same structure. Especially, they are more stable to air and moisture than the corresponding unsubstituted indenyl lanthanide complexes.

Synthesis and crystal structure of cyclopentylindene rare earth complex (C5H9C9H6)(3)SMCl-Li+ (THF)(4)

Rare earth complex (C5H9C9H6)(3)SmCl-Li+ (THF)(4)( I ) was synthesized by reacting anhydrous SmCl3 with two equivalents of C5H9C9H6Li. From mix-solvent of THF and hexane, red color single crystals were obtained. The crystal belongs to a cubic system, space group P2(1)3 with unit cell parameters a= b=c= 1. 754 0(2) nm, alpha=beta=gamma=90degrees, V=5. 396 4(11) nm(3), Z = 4. The ten-coordinated samarium atom is bonded to three cyclopentylindenyl rings and a chlorine atom to form the anionic part of the title complex, ring centroids and the chlorine atom form a tortured tetrahedron around samarium. In the cationic part, lithium atom coordinates to four oxygen atoms of THF molecules to form a normal tetrahedron. The Sm-C(within the same ring) distance varies from 0. 268 to 0. 299 nm.

Synthesis and characterization of tris(cyclopentylcyclopentadienyl)lanthanide complexes (C5H9C5H4)(3)NdBrLi(THF)(3) and (C5H9C5H4)(3)SmTHF

(C5H9C5H4)(3)NdBrLi(THF)(4)(1)(C5H9=cyclopentyl) was obtained from the reaction of NdCl3 with C5H9C5H4Na and LiBr (Nd:Na:Li=1:2:1 molar ratio) in THE X-ray crystallography showed that the ten-coordinated neodymium atom is bonded to three cyclopentylcyclopentadienyl(eta(5)) rings and a single bromine atom bridging a lithium which is bonded to three THF molecules. Complex 1 is triclinic, P1 space group with unit dimensions of a= 12.048(2), b= 13.498(3), c= 13.831(3)Angstrom, a = 104.16(3), beta = 104.07(3), gamma =95.96(3)degrees, V=2083.3(7)Angstrom(3), Z=2, D-c=1.35Mg/m(3) and F(000)=874. (C5H9C5H4)(3)SmTHF (2) was synthesized by reaction of anhydrous SmCl3 with C5H9C5H4Na at a molar ratio of 1:3. The structure was determined by X-ray crystallography. The ten-coordinated samarium atom is bonded to three cycloperrtylcyclopentadienyl rings and one oxygen of THF molecule to form a pseudo-tetrahedron. Complex 2 is orthorhombic, Fdd2 space group with unit cell dimensions of a =28.175(5)Angstrom, b =46.24(2) Angstrom, c =9.167(4) Angstrom(3), V=11943(8)Angstrom(3), Z= 16, D-c = 1.38Mg/m(3) and F(000)=5136.

Two new coordination polymers of Co(II) with 1,1 '-(1,4-butanediyl)bis(benzimidazole)

Two new compounds, [CoL2(H2O)(2)](NO3)(2). 8H(2)O (1) and [CoL(H2O)(2)(CH3CO2)(2)]. H2O (2), were obtained from self-assembly of the corresponding metal salts with 1,1'-(1,4-butanediyl)bis(benzimidazole) (L). In 1, each cobalt ion is coordinated to four nitrogen atoms from four molecules of L, and to two water molecules. Metal ions are bridged by L ligands to form infinite (4, 4) networks that contain 44-membered rings. The (4, 4) networks of 1 stack in a parallel fashion, resulting in the formation of large channels in the material. In 2, each cobalt ion is coordinated to two N atoms from two L molecules, two water molecules and two carboxylate O atoms from two acetate anions. Each L molecule is coordinated to two cobalt ions, acting as a bridging ligand as in 1. The bridged cobalt ions form an infinite zigzag chain structure.

A study of the crystallographic equivalence of ether and ketone groups in poly(aryl ether ketone)s

Crystallographic equivalence of ether and ketone in all para-substituted PAEKs crystallized in form I was discussed in this paper. In a word, crystallographic equivalence between ether and ketone groups is tenable when polymer contains only phenyl rings in the repeat unit. If a polymer contains a diphenyl group in the repeat unit, two cases should be distinguished. In the case of PEDEKK and PEEKDK, crystallographic equivalence between ether and ketone linkages is untenable, However, in the case of PEDK and PEDEKDK, crystallographic equivalence between ether and ketone linkages is still tenable.

Gas and water vapor transport through a series of novel poly(aryl ether sulfone) membranes

The permeation behavior of water vapor, H-2, CO2, O-2, N-2, and CH4 gases in a series of novel poly(aryl ether sulfone)s has been examined over a temperature range of 30-100 degreesC. These polymers include four alkyl-substituted cardo poly(aryl ether sulfone)s and four intermolecular interaction enhanced poly(aryl ether sulfone)s. Their water vapor and gas transport properties were compared to the unmodified cardo poly(aryl ether sulfone) (PES-C). It was found that the bulky alkyl substituents on the phenylene rings were advantageous for gas permeability, while the intermolecular hydrogen bonds and ionic bonds resulted in a considerable increase in gas permselectivity. The causes of the trend were interpreted according to free volume, interchain distance, and glass transition temperature, together with the respective contribution of gas solubility and diffusivity to the overall permeability. Of interest was the observation that IMPES-L, which simultaneously bears bulky isopropyl substituent and pendant carboxylic groups, displayed 377% higher O-2 permeability and 5.3% higher O-2/N-2 permselectivity than PES-C. Furthermore, sodium salt form PES-Na+ and potassium salt form PES-K+ exhibited water vapor permeability twice as high as PES-C and H2O/N-2 selectivity in 10(5) order of magnitude.

Metal ion and anion coordination in the thiamine-[Pt-II(NO2)(4)](2-) system. Structures of a metal complex, Pt(thiamine)(NO2)(3), and two salts, (H-thiamine)[Pt(NO2)(4)]center dot 2H(2)O and (thiamine monophosphate)(2)[Pt(NO2)(4)]center dot 2H(2)O

Reaction of thiamine or thiamine monophosphate (TMP) with K2Pt(NO2)(4) afforded a metal complex, Pt(thiamine)(NO2)(3) (1), and two salt-type compounds, (H-thiamine)[Pt(NO2)(4)]. 2H(2)O (2) and (TMP)(2)[Pt(NO2)(4)]. 2H(2)O (3), which were structurally characterized by X-ray diffraction. In 1, the square-planar Pt2+ ion is coordinated to the pyrimidine N(1'), a usual metal-binding site, and three NO2- groups. The thiamine molecule exists as a monovalent cation in 1 and a divalent cation in 2 while the TMP molecule is a monovalent cation in 3. In each compound, thiamine or TMP adopts the usual F conformation and forms two types of host-guest-like interactions with anions, which are of the bridging forms, C(2)-H . . . anion . . . pyrimidine-ring and N(4'1)-H(...)anion(...)thiazolium-ring. In 3, there is an additional anion-bridging interaction between the pyrimidine and thiazolium rings of TMP, being of the form C(6')-H . . . anion . . . thiazolium-ring. The salts 2 and 3 show similar hydrogen-bonded cyclic dimers of thiamine or TMP between which the anions are held. Results are compared with those of the other thiamine-platinum complexes. (C) 2001 Elsevier Science B.V. All rights reserved.

Host-guest-like thiamine-anion complexation in thiaminium bis(tetrafluoroborate)

In the title compound, 3-[(4-amino-2-methyl-5-pyrimidin-1-io)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium(2+) bis(tetrafluoroborate), C12H18N4OS2+. 2BF(4)(-), the divalent thiamine cation (in the F conformation) is associated with BF4- anions via two characteristic bridging interactions between the thiazolium and pyrimidinium rings, i.e. C-H . . . BF4- . . . pyrimidinium and N-H . . . BF4- . . . thiazolium interactions. Thiamine molecules are linked by N-H . . .O hydrogen bonds to form a helical chain structure.

Molecular dynamics simulation of sub-transition for polyethersulfone

Molecular dynamics (MD) simulations of a polyethersulfone (PES) chain are carried out in the amorphous state by using the Dreiding 2.21 force field at four temperatures. Two types of molecular motion, i.e, rotations of phenylene rings and torsions of large segments containing two oxygen atoms, two sulfur atoms, and five phenylene rings on the backbone, are simulated. The modeling results show that the successive phenylene rings should be in-phase cooperative rotations, whereas the successive large segments should be out-of-phase cooperative torsions. By calculating the diffusion coefficient for the phenylene ring rotations, it is found that this rotation contributes to the beta -transition of PES.

Synthesis and characterization of phenyl-capped oligoanilines

A series of phenyl-capped oligoanilines were prepared by chemical oxidation coupling. By comparing the FTIR spectra of fully reduced oligoanilines with those of oxidized oligoanilines, the intensity ratio of 1600cm(-1) to 1500cm(-1) was correlated to the content of the quinoid rings in the oligomer. In UV-Vis spectra of the oligoanilines in their oxidized state, the maximum absorption near 600nm redshifted from 540nm to 610nm with increasing polarity of the solvent, indicating the existence of tautomers in oxidized oilgoanilines.

The algorithm on ring perception of molecule

It's important to identify ring in the process of structure elucidation. In this paper, all rings and the smallest set of smallest ring(SSSR) of structure are obtained from two-dimensional connection table. The results are satisfactory by using this algorithm in ESESOC expert system as constraint.

In-situ FTIR study on adsorption and oxidation of native and thermally denatured calf thymus DNA at glassy carbon electrodes

In-situ Fourier transform infra-red (FTIR) spectra of native and thermally denatured calf thymus DNA (CT DNA) adsorbed and/or oxidized at a glassy carbon (GC) electrode surface are reported. The adsorption of native DNA occurs throughout the potential range (-0.2 similar to 1.3 V) studied, and the adsorbing state of DNA at electrode surface is changed from through the C=O band of bases and pyrimidine rings to through the C=O of cytosine and imidazole rings while the potential shifts negatively from 1.3 V to -0.2 V. An in-situ FTIR spectrum of native CT DNA adsorbed at GC electrode surface is similar to that of the dissolved DNA, indicating that the structure of CT DNA is not distorted while it is adsorbed at the GC electrode surface. In the potential range of -0.2 similar to 1.30 V, the temperature-denatured CT DNA is adsorbed at the electrode surface first, then undergoes electrochemical oxidation reaction and following that, diffuses away from the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis and characterization of soluble polyimides from 2,2-bis(4-aminophenyl)cycloalkane derivatives

New aromatic diamines [(1) and (2)] containing polycycloalkane structures between two benzene rings were synthesized by HCl-catalyzed condensation reaction of aniline hydrochloride and corresponding polycycloalkanone derivatives. The structures of diamines were identified by H-1-NMR, C-13-NMR, FTIR spectroscopy, and elemental analysis. The polyimides were synthesized from the obtained diamines with various aromatic dianhydrides by one-step polymerization in m-cresol. The inherent viscosities of the resulting polyimides were in the range of 0.34-1.02 dL/g. The polyimides showed good thermal stabilities and solubility. All the polymers were readily soluble in N-methyl-2-pyrrolidone, m-cresol, tetrachloroethane, etc. Some of them were soluble even in chloroform at room temperature. The glass transition temperatures were observed in the range of 323-363 degrees C, and all of the polymers were stable up to 400 degrees C under nitrogen atmosphere. (C) 1999 John Wiley & Sons, Inc.