Structure and thermal reactivity of some 2-substituted 1,3-oxathiolane S-oxides

Isomerization of 2-benzylidene-1,3-dioxolane to 3-phenylbutyrolactone occurs readily under flash vacuum pyrolysis (FVP) conditions. 2-Diphenylmethyl-1,3-oxathiolane and 2-benzyl-1,3-oxathiolane have been prepared and the latter compound has been oxidized to the corresponding sulfoxide, whose structure and conformation are examined by ¹H NMR, and to the sulfone whose X-ray structure is determined. 2-Benzylidene-1,3-oxathiolane is also prepared and the behavior of the three S-oxidized oxathiolane derivatives upon FVP is examined. While extrusion of SO_n to give ethene and a carbonyl compound predominates in all three cases, the sulfoxide gives also bis(2-hydroxyethyl) disulfide, most likely formed via thiirane S-oxide and 1,2-oxathietane.     

Crystallization and Purification of 4,4′-Diaminodiphenyl Ether

The purification of 4,4′-diaminodiphenyl ether (ODA) was investigated. ODA, which contained impurities, was sublimated and anti-solvent (ethanol)-crystallized in N-dimethylformamide (DMF). Fourier transform infrared (FTIR) results revealed that the sublimated crystal was basically identical with the pure ODA sample. The influence of different amounts of ethanol on particle size distribution was analyzed during anti-solvent crystallization. The morphology of the ODA crystal was examined by scanning electron microscopy (SEM). The color of the sample enhanced from a brown powder to a colorless granular crystal. The purity of the sample could be increased from about 30 % to 87 %. With the operations of sublimation and anti-solvent crystallization, the purity, crystal morphology, and particle size distribution of ODA were significantly improved.     

装饰材料用阻燃柔性复合薄木的制备及力学性能

以厚度为0.35～0.40 mm的榉木为薄木基材、棉网格布为增强材料和PES(聚醚砜)型HMA(热熔胶)为胶粘剂,选用BL-环保阻燃剂制备装饰材料用阻燃柔性复合薄木;然后以拉伸强度、剥离强力和表观性能为衡量指标,以热压压力、热压温度、含水率和胶膜厚度为试验因素,采用正交试验法优选制备柔性复合薄木的最优方案。结果表明:以PES型HMA作为薄木/棉网格布复合用环保型胶粘剂,其不仅与BL-环保阻燃剂有很好的相容性,而且可避免脲醛树脂胶粘剂的甲醛释放等问题;增强型薄木与非增强型薄木相比,前者的横纹拉伸强度显著提高,并且前者不再表现为脆性特征;柔性复合薄木热压工艺条件的最优方案为热压压力0.7 MPa、热压温度125℃、含水率12%和胶膜厚度0.10 mm。     

消除聚苯醚砜塑料件熔接线开裂

从制品设计、模具设计、脱模剂选择及成型工艺诸方面，论述工程塑料苯醚砜塑料件熔接线开裂的产生原因及消除方法。     

Asymmetric induction in forming poly(olefin sulphone)s

Poly(1-olefin sulphone)s have been prepared from olefins with a chiral centre at the carbon atom adjacent to the double bond. In ¹³C and ¹H NMR studies on the polymers obtained by free radical copolymerisation it has been found that the chirality of a main chain methine carbon that forms part of the backbone depends upon the chirality of the carbon initially present within the same hydrocarbon residue. The introduction of bulky groups into the chiral group of the monomeric olefin increased the ratio of diastereoisomers formed within the residue. In the most favoured case 69% of the backbone chiral centres were fixed with reference to the side chain structures. By employing a simple theory based upon an enumeration of steric interactions and upon the γ-gauche effect on carbon chemical shifts, it was deduced that the main chain chiral centre preferred to adopt the opposite stereochemistry to that of the side chain when that carries an ethyl group, a methyl group and a hydrogen atom. A bias was also found at the backbone when the monomer chiral centre contained polar acid or ester groups.     

Copolymerization of aniline and 4,4′-diaminodiphenyl sulphone and characterization of formed nano size copolymer

Aniline was copolymerized chemically in presence of five different concentrations of 4,4′-diaminodiphenyl sulphone using potassium persulphate. The copolymer exhibited good solubility in DMF and DMSO. Copolymers were characterized by UV-VIS, FTIR, XRD and SEM studies. The formation of polymer through N-H group was understood from the single N-H stretching vibrational frequency at 3378 cm⁻¹ and bands at 1630 and 1494 cm⁻¹ for quinonoid and benzenoid structures, respectively. The stretching vibration of sulphone SO at 1115 cm⁻¹ clearly indicated the presence of DDS in the copolymer. The X-ray diffraction studies revealed the formation of nano sized crystalline copolymer. When more DDS was incorporated in the copolymer the crystalline nature changed from less to more. The grain size of the copolymer calculated from Scherrer's formula was 83 nm. The nano size copolymer formation was also confirmed through surface morphology (100 nm) studies. The electrical property of the copolymer was studied by four-probe conductivity meter. The synthesized polymers have conductivity of 7.21 × 10⁻³ to 2.07 × 10⁻³ S cm⁻¹. The voltammetric and spectroelectrochemical results were also presented.     

Studies on epoxy/calcium carbonate nanocomposites

The article describes the preparation of epoxy‐calcium carbonate nanocomposites using diaminodiphenyl sulfone (DDS) as a curing agent. The curing behavior of diglycidyl ether of bisphenol‐A (DGEBA) (1 mol) in the presence of varying amounts of nanocalcium carbonate was investigated by differential scanning calorimetry (DSC) using stoichiometric amounts of diaminodiphenyl sulphone (0.5 mol) as curing agent. The amount of calcium carbonate (～ 44 nm) was varied from 2% to 10% (w/w). In the DSC scans of these samples, a broad exothermic transition due to curing was observed in the temperature range of 110–335°C. As expected, heat of curing decreased with increasing amount of nanocalcium carbonate; however it did not affect the curing characteristics, thereby indicating that the filler did not hinder the curing reaction. Thermal stability of DGEBA in the presence of varying amounts of nano‐CaCO₃ after isothermal curing [(i.e., by heating in an air oven at 80°C (1 h), 100°C (1 h), 120°C (1.5 h), and 180°C (4 h)] was evaluated by thermogravimetry. All the samples were stable upto 350°C, and char yield at 800°C increased with increasing amount of nanocalcium carbonate. Rectangular bars were prepared by mixing DGEBA, DDS, and varying amounts of CaCO₃ using silicone mold. The nanocomposites were characterized by X‐ray, scanning electron microscopy (morphological characterization), and dynamic mechanical analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Characterisation of Sulphonated Poly(arylene sulphone) Terpolymers with Triphenylphosphine Oxide Moieties for Proton Exchange Membrane Fuel Cells

For application in fuel cells, a series of sulphonated poly(phenylene sulphone) terpolymers with triphenylphosphine oxide moieties as constitutional units in the polymer backbone have been prepared. The synthesis of the terpolymers represents a two‐step process including: (i) an aromatic nucleophilic substitution polycondensation of three difluoro monomers with varying ratios, i.e. 3,3′‐disulphonate‐4,4′‐difluorodiphenylsulphone, 4,4′‐difluorodiphenylsulphone and bis(4‐fluorophenyl)phenyl phosphine oxide (BFPPO), with 4,4′‐thiobisbenzenethiol yielding sulphonated poly(phenylene sulphide) terpolymers (sPPSPO) and (ii) their following oxidation with hydrogen peroxide in acidic solution to yield sulphonated poly(phenylene sulphone) terpolymers (sPPSO2PO). The structures and molecular compositions were confirmed by ¹H and ¹³C NMR spectroscopy. The ion exchange capacity (IEC) was adjusted at will choosing the appropriate ratio of sulphonated and unsulphonated monomers. Terpolymers with 1.72 ≤ IEC ≤ 2.32 have been obtained. Sulphonated poly(arylene) ionomers containing only sulphone (–SO₂–) linkages and phosphine oxide (–PO–) units rather than ether or sulphide in the backbone reveal a high thermal and oxidative stability. Membranes were cast either from dimethylformamide (DMF) or from dimethyl sulphoxide (DMSO) solutions. For all terpolymers some general characteristic trends were observed, such as an increase of the proton conductivity with increasing IEC, water uptake and temperature. The series of sPPSO2PO membranes offered high conductivities at high humidification, however, their performance strongly depends on the relative humidity. The mechanical properties of sulphonated poly(phenylene sulphone)s have been considerably improved by means of terpolymerisation with phenylene oxide moieties. Even under high humidification the terpolymers form clear, flexible membranes the stress at break of some membranes exceeds that of Nafion® under the same conditions by 40%.     

聚苯醚砜注射成型

介绍耐高温热塑性工程塑料聚苯醚砜树脂的注射成型设备、模具和注射工艺等。     

Aromatic-aliphatic copolyesters: structure and properties

Aromatic-aliphatic copolyesters synthesized by interfacial polycondensation were characterized by differential scanning calorimetry. X-ray diffraction and density measurements. A decrease in the T_g and melting temperature was observed on increasing the glycol content of the copolyesters. The wholly aromatic polyesters showed changes both in the Bragg angle position and intensity of the reflections, whereas in the aromatic-aliphatic copolyesters no sharp change was observed.