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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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
ABSTRACT
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.