Compatibilisation of blends of poly(vinyl chloride) and poly(styrene-block-(ethylene-co-butadiene)-block–styrene) with maleic anhydride grafting

Abstract

The mechanical properties of blends of poly (vinyl chloride) (PVC) and poly (styrene-block-(ethylene-co-butadiene)-block–styrene) (SEBS) were investigated using maleic anhydride grafted SEBS (SEBS-g-MAH) as a compatibiliser. The results indicated that addition of a small amount of SEBS-g-MAH during melt blending significantly improved the mechanical properties of PVC/SEBS blends. The impact strength of the compatibilised PVC/SEBS blends was found to reach a maximum of 53·5±2·78 KJ m^?2 at room temperature and a maximum of 32·8±1·66 KJ m^?2 at ?20°C at an SEBS-g-MAH loading level of 6 phr. The two glass transition temperatures of the components in the blends converged to some degree upon addition of SEBS-g-MAH for compatibilisation. At room temperature the dynamic storage modulus of the compatibilised blends was higher than that of the blends without compatibilisation. The size of the dispersed phase domains in the blends was appreciably reduced on addition of SEBS-g-MAH during melt blending according to scanning electron microscopy. All the above observations revealed that SEBS-g-MAH enhanced the compatibility between PVC and SEBS in the PVC/SEBS blends.     

Mechanism of thermal generation of poly(p-phenylene vinylene) from poly(p-xylene-α-dimethylsulphonium halides)

The thermal conversion of poly(p-xylene-α-dimethylsulphonium halides) into poly(p-phenylene vinylene) (PPV) can occur through two concomitant reactions. The principal reaction is an elimination of dimethyl sulphide and halogen acid, while the second reaction, an undesirable one, is the nucleophilic attack of the halide counterion on a methyl group to form the methyl halide and a methyl sulphide. The two thermal processes were observed in the pyrolysis of both poly(p-xylene-α-dimethylsulphonium bromide) and poly(p-xylene-α-dimethylsulphonium chloride). On storage at room temperature, poly(p-xylene-α-dimethylsulphonium halides) undergo partial decomposition to PPV, as shown by thermogravimetric experiments. The flash pyrolysis-gas chromatography-mass spectrometry of PPV obtained by the thermal conversion of poly(p-xylene-α-dimethylsulphonium bromide) at 400°C was also investigated.     

Electrochemical study of β-diketonatobis(triphenylphosphite)rhodium(I) complexes

The electrochemical behaviour of the series of ten [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes with R, R′ = CF₃, CF₃ (1), CF₃, CH₃ (2), CF₃, Ph (C₆H₅) (3), CF₃, Fc (ferrocenyl = (C₅H₅)Fe(C₅H₄)) (4), CH₃, Ph (5), CH₃, CH₃ (6), Ph, Ph (7), Fc, CH₃ (8), Fc, Ph (9) and Fc, Fc (10) were studied in acetonitrile containing 0.100 mol dm⁻³ tetra-n-butylammonium hexafluorophosphate as supporting electrolyte utilizing a glassy carbon working electrode. Results are consistent with Rh(I) being first oxidized in an electrochemically irreversible two-electron transfer process at peak anodic potentials ranging E_pa(Rh) = 0.124–0.881 V vs. Fc/Fc⁺. For the ferrocene-containing complexes (4), and (8)–(10) the rhodium oxidation was followed by the electrochemically reversible oxidation of the ferrocenyl group in a one-electron transfer process at a slightly more positive potential. Relationships were established between the electrochemical quantity E_pa(Rh) and kinetic parameter log k₂ as well the sum of experimental group electronegativities (Gordy Scale) of the R and R′ groups (χ_R + χ_R′), the Hammett σ values (σ_R + σ_R′) and the Lever ligand parameter E_L for the [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes: E_pa(Rh) (vs. Fc/Fc⁺/V) = 0.31 (χ_R + χ_R′)–1.09 = 0.56 (σ_R + σ_R′) + 0.28 = S_M (ΣE_L) + (I_M − 0.66 V) = −0.23 log k₂ − 0.03 (k₂ = second order rate constant for the oxidative addition of methyl iodide to rhodium). A profound shift of E_pa(Rh) to a more positive potential was observed for Rh(I) substrates containing β-diketonato ligands with increasing electronegative substituents R and R′. An exponential dependence of E_pa(Rh) on the pK_a of the β-diketone was obtained.     

One-Pot Synthesis of Poly(linoleic acid)-g-Poly(styrene)-g-Poly(ε-caprolactone) Graft Copolymers

One-pot synthesis of graft copolymers by ring-opening polymerization and free radical polymerization using polymeric linoleic acid peroxide (PLina) is reported. Graft copolymers having structures of poly(linoleic acid)-g-polystyrene-g-poly(ε-caprolactone) were synthesized from PLina, possessing peroxide groups on the main chain by the combination of free radical polymerization of styrene and ring-opening polymerization of ε-caprolactone in one-step. Principal parameters, such as monomer concentration, initiator concentration, and polymerization time, which effect the one-pot polymerization reactions were evaluated. The obtained graft copolymers were characterized by ¹H-NMR and DOSY-NMR spectroscopy, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry techniques.     

Understanding the Potential In Vitro Modes of Action of Bis(β-diketonato) Oxovanadium(IV) Complexes

To understand the potential in vitro modes of action of bis(β-diketonato) oxovanadium(IV) complexes, nine compounds of varying functionality have been screened using a range of biological techniques. The antiproliferative activity against a range of cancerous and normal cell lines has been determined, and show these complexes are particularly sensitive against the lung carcinoma cell line, A549. Annexin V (apoptosis) and Caspase-3/7 assays were studied to confirm these complexes induce programmed cell death. While gel electrophoresis was used to determine DNA cleavage activity and production of reactive oxygen species (ROS), the Comet assay was used to determine induced genomic DNA damage. Additionally, Förster resonance energy transfer (FRET)-based DNA melting and fluorescent intercalation displacement assays have been used to determine the interaction of the complexes with double strand (DS) DNA and to establish preferential DNA base-pair binding (AT versus GC).     

Rheological properties of poly(ε-caprolactone) and poly(styrene-co-acrylonitrile) blends

Summary Rheological properties of poly(-caprolactone) (PCL) and Poly (styrene-co-acrylonitrile) (SAN) blends were examined as a function of the acrylonitrile (AN) content in SAN, to systematically understand the correlation between the interaction parameter and the theological properties of miscible polymer blends. When the plateau modulus (G _N ⁰) and zero shear viscosity ( ₀) of the PCL/SAN blends are plotted against the AN content in SAN, a minimum is observed. Qualitatively, the results obtained parallel the variation of the interchain interaction with the AN content. The negative deviation ofG _N ⁰ and ₀ from linearity seems to be attributed to the increase in the entanglement molecular weight between dissimilar chains which results from the chain extension caused by interchain interaction.     

List of Reviewers (2000.12-2001.12)

BAO Yongzhong（包永忠）CAI Xingxiong（蔡兴雄）CAO Guiping（曹贵平）CAO Tongyu（曹同玉）CAO Zhu'an（曹竹安）CAo Zhuyou（曹竹友）CEN Peiling（岑沛霖）CHEN Gantang（陈甘棠）CHEN Guangjin（陈光进）CHEN Huanqin（陈焕钦）CHEN Jiayong（陈家镛）CHEN Jiti（陈集体）CHEN Songying（陈诵英）CHEN Tingkuan（陈听宽）CHEN Xi（陈曦）CHEN Zhongqi（陈钟颀）DAI Gance（戴干策）DAI Yongyuan（戴猷元）DENG Xiu（邓修）     

NanoZnO initiated polymerization of N-vinylcarbazole (NVC) and evaluation of a poly(N-vinylcarbazole)–ZnO nanocomposite

The polymerization of N-vinylcarbazole was conducted in bulk in presence of ZnO without any external initiator and a nanocomposite of poly(N-vinylcarbazole)–ZnO (PNVC–ZnO) was isolated from the system. The polymerization of N-vinylcarbazole by ZnO impregnated with acetylene black (AB) and Fe³⁺ was also conducted to isolate the respective AB and Fe³⁺ loaded PNVC–ZnO composites, PNVC–ZnO(AB) and PNVC–ZnO(Fe³⁺). The formation of the poly(N-vinylcarbazole) in these systems was confirmed by FTIR, UV–vis and emission spectroscopic analysis. TGA, DSC and SEM characteristics of these composites were evaluated in details. XRD analysis revealed no crystanillity in poly(N-vinylcarbazole) moiety. PNVC–ZnO was nonconducting but PNVC–ZnO(AB) and PNVC–ZnO(Fe³⁺) systems exhibited conductivities in the range 0.12 and 10⁻³ S/cm respectively. A carbocationic propagation pathway was suggested to explain the initiation of N-vinylcarbazole by Zn⁺⁺ moiety in ZnO. Kinetic studies revealed that the polymerization is first order with respect to ZnO and the monomer concentration respectively.     

List of Reviewers (2001.12-2002.12)

CAO Kun(曹堃)CAO Xuejun(曹学君)CAO Zhu’an(曹竹安)CEN Peilin(岑沛霖)CHANG Zhidong(常志东)CHEN Biaohua(陈标华)CHEN Fengqiu(陈丰秋)CHEN Guanwen(陈观文)HAN Wei(韩伟)HE Chaohong(何潮洪)HE Xiaorong(何小荣)HU Haoquan(胡浩权)HU Shanying(胡山鹰)HU Wangming(胡望明)HU Yangdong(胡仰栋)HU Zongding(胡宗定)     

Synthesis and characterization of 4,4’–(dimethylsilylene) bis( phenyl chloroformate) and 4,4’–(dimethylgermylene)bis(phenyl chloroformate) and their use in the synthesis of poly(urethanes)

Summary The synthesis of 4,4–(dimethylsilylene)bis(phenyl chloroformate) and 4,4–(dimethylgermylene)bis(phenyl chloroformate) is described according to the same route for the synthesis of bisphenol–A bischloroformate. These compounds were characterized using elemental analysis, FT–IR and NMR spectroscopy. Poly(urethanes) derived from these bischlororformates containing silicon or germane in the main chain, were obtained in benzene solution by reaction with 4,4–methylenedianiline in the presence of pyridine. Poly(urethanes) were characterised by spectroscopic methods and the thermal properties (Tg and thermal stability) were compared with the homologue poly(urethane) obtained from bisphenol–A chloroformate.     

Adsorption of Cr (VI) on synthetic hematite (α-Fe2O3) nanoparticles of different morphologies

The adsorption of Cr (VI) from aqueous solution onto nanoparticles hematite (α-Fe₂O₃) of different morphologies synthesized by acid hydrolysis, transformation of ferrihydrite, sol gel methods has been investigated. The hematite particle sizes were in the range 15.69-85.84 nm and exhibiting different morphologies such as hexagonal, plate-like, nano-cubes, sub-rounded and spherical. The maximum adsorption capacity of Cr (VI) was found to be in the range 6.33–200 mgg^?1 for all hematite samples. The kinetics of sorption was rapid, reaching equilibrium at 45–240 minutes. Sorption kinetics and equilibria followed pseudo-second order and Langmuir adsorption isotherm models. The rate constants were in the range 0.996–2.37×10^?2 g/mg/min for all samples. The maximum adsorption was attained at pH 3.0, while adsorption decreased as the pH increased from pH 3.0 to 10.0. The study revealed that the hematite with plate-like morphology has the highest adsorption capacity. The sorption process has been found to be feasible following a chemisorption process, and adsorption of Cr (VI) onto hematite nanoparticles was by inner sphere surface complexation due to low desorption efficiency in the range 9.54–53.4%. However, the result of ionic strength revealed that the reaction was by outer sphere complexation. This study showed that morphologies play a vital role in the adsorption capacities of samples of hematite in the removal of Cr (VI) from aqueous solution.     

Use of HPLC in the identification of cis and trans-diaquabis(2,2′-bipyridine)ruthenium(II) complexes: crystal structure of cis-[Ru(H2O)2(bpy)2](PF6)2

[Ru(H₂O)₂(bpy)₂](PF₆)₂ complex was obtained by reacting HPF₆ in a [Ru(CO₃)(bpy)₂] aqueous solution. The complex can exist as cis and trans isomers and usually has been used in the preparation of several ruthenium–bipyridine species. Despite the possibility to have contamination of a specie in another, there is no analytical control involving the characterization of both complexes. Based on this we have proposed the use of high-performance liquid chromatography (HPLC) as an analytical technique to control the purity of cis and trans isomers. The separation was performed using a CLC-ODS column. The cis isomer eluted at 9.4 min while trans isomer eluted at 4.3 min. In aqueous solution the trans and cis isomer configurations were confirmed by NMR spectra (¹H). The attribution of cis isomer was also made based on the X-ray crystal structure (monoclinic, P2_1/c, a=12.320(2), b=13.852(2), c=34.220(3) Å, β=91.89(1)°, Z=8) which is reported. The six-coordinated ruthenium atom is chelated by two bipyridines and two molecules of H₂O.     

Distribution of the number of arms of (PSt)f−n-star-(PIs)n hetero-star block copolymers prepared via anionic living polymerization of macromonomers

The distributions of the number of arms (DNA) of (polystyrene)_6.2-star-polyisoprene ((PSt)_6.2-star-PIs) and (PSt)_7.6-star-(PIs)_6.3 hetero-star block copolymers and its precursors prepared via anionic living polymerization of macromonomers have been determined by plotting a weight fraction of the number of arms against the number of arms. Three-dimensional molecular weight distributions (3D-M_wD) of the two hetero-star block copolymers and its precursors were also determined by plotting a weight fraction at the ith elution volume against the corresponding molecular weight (M_i) and ith elution volume using GPC in conjunction with a low-angle laser light-scattering detector, a refractive index detector, and an ultraviolet detector. A non-linear relationship between the ith elution volume and M_i of (PSt)_6.2-star-PIs was observed and explained from a g_star perspective. The present paper describes the analytical method for determination of the DNA using the M_wD. The DNAs of the six samples were found to be narrow and similar to the M_wDs of the corresponding samples. The synthetic mechanism of the hetero-star block copolymers was discussed from a DNA perspective.     

Formation of a covalently-linked bimetallic compound upon irradiation of tris(1,4,5,8-tetraazaphenanthrene)ruthenium(II) in the presence of 5′-guanosine-monophosphate

A new type of binuclear Ru(II) complex [Ru(TAP)₂(TAP-TAP)Ru(TAP)₂]⁴⁺ (1) (TAP-TAP=2,2′-bis(1,4,5,8-tetraazaphenanthrene)) produced by photo-reaction of Ru(TAP)₃²⁺ in the presence of 5′-guanosine-monophosphate (5′-GMP) has been isolated and characterised. The formation of 1 is proposed to proceed via mono-reduced Ru(TAP)₃²⁺, i.e. [Ru²⁺(TAP)₂(TAP^⋅−)]⁺. The emission lifetime of 1 is much greater than that of Ru(TAP)₃²⁺, consistent with an increased energy gap between the ³MLCT and ³MC states in 1. This arises because of stabilisation of its ³MLCT state due to the localisation of the excited state electron on the TAP-TAP ligand.     

Thermal decomposition of some poly(β-hydroxyalkanoates)

The thermal decomposition of some polyhydroxyalkanoates (PHA) has been investigated by means of thermogravimetry and differential thermogravimetry. The thermal stability of the studied polyesters decreases slightly with increasing hydroxyvalerate (HV) comonomer. This result is different from those reported in the literature. Other results agree with reaction mechanisms proposed in the literature. The data from dynamic thermogravimetric experiments are consistent with a first order reaction, as would be expected from the reaction mechanism. Infrared spectra of the thermally degraded and undegraded copolymers are evidence of the cis-elimination mechanism. © 1999 Society of Chemical Industry