Iranian Polymer Journal / Volume 9 Number 3 (2000) 133142 ISSN: 1026-1265/2000
High-density/Linear Low-density Polyethylene Blends
S.H. Jafari and S.K. Rana
Centre for Polymer Science and Engineering, Indian Institute of Technology, New Delhi 110 016, India
Morphologically distinct binary polymer blends have been prepared by melt mixing of high-density polyethylene (HDPE) and various linear low-density polyethylene (LLDPEs) for the entire range of blend composition under identical processing conditions. The morphology of the tensile fracture surfaces of the parent polymers and their blends are quite interesting and show good correlation with thermal and mechanical properties. The HDPE forms linear and interpenetrating fibrils with large interfibrillar separation, whereas, octene containing LLDPE (OLLDPE) with almost equal number of branching to that of HDPE shows nicely formed twisted fibrils. On the other hand, pentene containing LLDPE (PLLDPE) manifests a straight fibrillar morphology with well defined boundary comprising many thin fibrils with alternative thick and thin regimes and perfection, whilst butene containing LLDPE (BLLDPE) shows thick comparatively smooth and well defined and imperfect boundary of tensile fracture. The blends morphology is quite distinct to that of parent polymers. The physical properties, melting and crystallization behaviour show good correlation to the fineness, twisting and discontinuity of the fibrils.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 143151 ISSN: 1026-1265/2000
Chemical Cleaning of Ultrafiltration Membranes
S.S. Madaeni and S. Sharifnia
Chemical Engineering Department, Razi University, Kermanshah, I.R. Iran
A hydrophobic polysulphone ultrafiltration membrane was used for whey processing. Fouled membranes were cleaned with acids (HCl and H2SO4), alkali (NaOH) and surfactant. The latter resulted in maximum flux recovery and resistance removal. Sodium hydroxide had moderate effect and hydrochloric acid was the weakest cleaning agent. This is due to the cleaning strength of emulsifiers compared to acid or alkali. However alkaline solutions are more efficient than acids for removal of organic compounds such as proteins. Cleaning efficiency depends on the concentration of cleaning agent being higher for higher surfactant concentration. For acids and alkali, the efficiency increases with increasing the concentration of the reagent reaches to a maximum (optimum concentration) and then decreases. Operating conditions affect the cleaning process. At higher stirring speeds (turbulent flow) or longer cleaning time better removal of deposits and higher cleaning efficiency were observed. The sequential cleaning process may or may not improve the cleaning efficiency. When alkaline cleaning was followed by acidic washing no improvement was achieved. This can be attributed to the removal of most of the reversible deposits by alkali. If the sequence is in the opposite direction an improvement in cleaning efficiency is obtained.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 153162 ISSN: 1026-1265/2000
Reinforcing Effects of Precipitated Silicas on Properties of Some
Vulcanizates of Styrene-butadiene Rubber
M.A. Ansarifar, J.P. Chugh and S. Haghighat
Institute of Polymer Technology and Materials Engineering, Loughborough University,
Loughborough, Leicestershire LE11 3TU, UK
The tear strengths of some conventional accelerated-sulphur vulcanizates of styrene-butadiene rubber (SBR) with a sulphur to accelerator ratio of ~1.8, containing no filler, 10, 30, or 50 parts per hundred rubber by weight (pphr) precipitated amorphous white silica filler type VN3 were measured. The tear tests were performed at different rates ranging from 0.017 to 8.33 mm/s, at an angle of 180º and at an ambient temperature (~23 ºC). The tear strengths of the vulcanizates improved progressively and quite substantially with silica; a trend which continued strongly when the amount of silica in the formulation was increased to 50 pphr, but remained mostly unaffected by changes in the rate of tear. For instance, the tearing energy rose by almost two orders of magnitude, from ~1.5 to ~100 kJ/m2 at a tear rate of 0.017 mm/s, when 50 pphr silica was loaded into the rubber. Likewise, the hardness of the vulcanizates, which was measured at 24.5 ºC and a 15 s instant, was enhanced significantly from ~35 to ~65 Shore A, when silica was added and then increased progressively to its full amount in the rubbers.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 163167 ISSN: 1026-1265/2000
Application of Polydimethylsiloxane as Adsorbent for
Detection of Aliphatic Hydrocarbon Compounds Vapours Using
Quartz Crystal Microbalance (QCM)
A. Mirmohseni and V. Hassanzadeh
Faculty of Chemistry, University of Tabriz, Tabriz, I.R. Iran
Polydimethylsiloxane (PDMS) was used as adsorbent for detection and determination of some aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and cyclohexane. The contamination of environment by these volatile organic compounds is a serious problem due to their potential human toxicity. Therefore, analysis of these compounds has become more and more important and various techniques have been developed to target this aim. A thin layer of PDMS was coated at the surface of an AT-cut gold-coated quartz crystal electrodes and a sensor based on the technique of quartz crystal microbalance has been developed for the detection of these organic vapours. Detection was based on the measurement of the frequency shifts due to the adsorption of the organic compounds on the polymer film. Calibration graphs were constructed by plotting the frequency changes (DF/Hz) against the concentration of organic compounds. Using this method, the detection of these organic vapours was successfully carried out at parts per million concentrations.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 169175 ISSN: 1026-1265/2000
An Investigation on Painting Polymer with Light Emission Ability
on a Substrate and Three Means to Enhance the Light Emission
to Fabricate New Display Devices
A. Talaie1,2,6,7, Y.K. Lee3, J. Jang1, D.J. Choo4, K.M. Kim3, S.H. Park4, G. Huh4, J.Y. Lee5,
T. Taguchi6, E. Maeder7and N. Esmaili8
(1) Physics Department, Kyung Hee University, Dongdaemoon-ku, Seoul, Korea
(2) Chemical Engineering Department, The Sydney University, Sydney NSW 2006, Australia
(3) Information Display Department, Kyung Hee University, Dongdaemoon-ku, Korea
(4) Chemistry Department, Kyung Hee University, Dongdaemoon-ku, Seoul, Korea
(5) Chemistry Department, The University of New South Wales, Sydney, Australia
(6) Polymer Interfaces Department, Osaka National Research Institute, Japan
(7) Polymer Institute Dresden, Hohe Strasse 6, Germany
(8) Computer Science and Engineering, The University of New South Wales, Sydney, Australia
In this paper we report on the ways to improve the light emission intensity and photoluminescence (PL) properties of poly(p-phenylene vinylene), PPV, based materials by means of doping, copolymerization and also by the use of a vacuum/inert system. We doped the polymer with iron via utilization of the laser ablation technique. Using this method, different amounts of iron were incorporated to the polymer when the laser source was used for the periods of 60 and 120 s. The improvement of PL intensity was experienced for 60 s of doping compared with undoped polymer. We also experienced improvement in PL properties of PPV based materials when 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene (MEH), 2,5-bis(chloromethyl)-methoxy-4-(2-cyclo-hexylethyl-oxy)benzene (MCHE)-PPV copolymer was used. A 1:1 ratio of MEH-PPV and MCHE-PPV was found to be the best ratio for an optimum PL intensity for this copolymer. We also pointed out that the use of vacuum and inert environment is crucially important in improvement of the light emitted from the polymer. In the final step of this investigation a computer algorithm was used to classify the copolymers from doped polymers, which was carried out with very accurate predictions of the different classes of the polymers under study.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 177181 ISSN: 1026-1265/2000
Etherial Base Azo‑2‑naphthol‑furfuraldehyde Oligomer Dyes
C.K. Desai and K.R. Desai
Department of Chemistry, South Gujarat University, Surat-395 007, Gujarat, India
A series of new oligomeric disperse dyes were prepared by coupling various aromatic ethers diazonium salts to 2‑naphthol-furfuraldehyde (2‑NF) oligo-mers. They were evaluated in terms of their yields, colour, solubility, IR and UV visible spectra, and the structure-property relationship are also discussed and their dyeing on polyester PET and nylon‑6,6 are assessed. Dyeing on polyester and nylon‑6,6 resulted in yellow, orange and cream to light pink coloration having excellent light fastness and washing fastness properties.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 183189 ISSN: 1026-1265/2000
Surface Modification of SBR and NR by Hydrophilic Monomers
(I): Effect of Structural Parameters and Inhibitors
M. Yeganeh‑Ghotbi1 and V. Haddadi‑Asl2
(1) Department of Chemistry, Faculty of Science, University of Tehran, Tehran, I.R. Iran
(2) Department of Polymer Engineering, Amir Kabir University of Technology, Tehran, I.R. Iran
Radiation grafting of two hydrophilic monomers (i.e., acrylamide and acrylic acid) onto styrene‑butadiene rubber (SBR) and natural rubber (NR) by the simultaneous method was studied. Attempts to graft SBR and NR in aqueous solution of acrylic acid and acrylamide lead to extensive homopolymerization. Metal‑based homopolymerization inhibitors including Mohr's salt and cupric nitrate were evaluated and found to prevent homopolymerization and significantly increase graft yield. The role of substrate structure on grafting efficiency for two hydrophilic monomers was investigated. The properties of the resulting copolymers have been studied by SEM techniques.
Iranian Polymer Journal / Volume 9 Number 3 (2000) 191196 ISSN: 1026-1265/2000
(II): Effect of Water Uptake, Wettability and Biocompatibility
V. Haddadi‑Asl1 and M. Yeganeh‑Ghotbi2
(1) Department of Polymer Engineering, Amir Kabir University of Technology, Tehran, I.R. Iran
(2) Department of Chemistry, Faculty of Science, University of Tehran, Tehran, I.R. Iran
Acrylamide and acrylic acid have been grafted to the surface of two vulcanizate natural and styrene‑butadiene rubbers using the simultaneous radiation method. Various conditions, including differing monomer concen-trations and additives, have been used. The treated rubbers have been characterized by measuring water uptake, hardness and tensile strength. In addition, some initial biocompatibility trials have been conducted, using cell attachment and spreading of Aveolar macrophages on the surface of the modified and unmodified samples as criteria. The physical and mechanical properties of the resulting copolymers have also been studied.