Iranian Polymer Journal / Volume 6 Number 2 (1997) 7786 ISSN: 1026-1265/1997
Improved van der Waals Equation of State
A. Eliassi and H. Modarres
Chemical Engineering Faculty, Amir Kabir University of Technology, Tehran, I.R. Iran
In this work the improved van der Waals equation of state which has been used for vapour‑liquid equilibria of polymer‑solvent mixtures by previous workers, is extended to consider liquid‑liquid equilibria by calculating and evaluating its third parameter (c) for several solvents and polymers such as benzene, cyclohexane, methylacetate, ethylacetate, propylacetate, acetone, polystyrene, polyisobutylene, polyvinylacetate. Also solvent activity in binary mixtures such as: benzene‑polyisobutylene, cyclohexane‑polyisobutylene, ethylacetate‑polyvinylacetate, propylacetate‑polystyrene, and acetone‑polystyrene at various concentrations is evaluated and compared with the experimental results and that of UNIFAC‑FV results. The molar volume and activity calculation indicated that this equation has a higher predictability in phase equilibria calculation compared with methods such as UNIFAC‑FV. The results showed that the improved van der Waals equation of state can give both upper and lower critical solution temperatures in liquid‑liquid equilibria calculations, and this can be considered as an advantage over similar calculation procedures which can only give upper critical solution temperature. It has become evident, however, that using a suitable temperature functionality for the adjustable parameter, kij, can improve the results.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 8796 ISSN: 1026-1265/1997
Investigations on Copolymerization of p‑Benzoquinone with
Vinylpyridine in Presence of Triethylamine
Y. Asif Nagiev, K. Matanat Mirmekhtieva and A. Bakhtiyar Mamedov
Institute of Polymer Materials, Azerbaijan Academy of Science, Sumgait, Republic of Azerbaijan
Copolymerization reaction of p‑benzoquinone and vinylpyridine in the presence of triethylamine has been investigated. It is found that as a result of the reaction of these comonomers, the copolymer and homopolymers of quinone and hydroquinone are formed. Using dilatometry method, the kinetics of copolymerization has been studied and an order of reaction for reacting components, rate constants and activation energies of the process have been determined. The weak intermolecular bonds in complexes of p-benzoquinone and vinylpyridine in hexane have been ascertained by means of UV‑spectroscopy. It is found that such complexes make an essential contribution both in initiation process and in formation of macromolecules. The compositions, structure and the properties of synthesized copolymer, including kinetic parameters of its oxidation by molecular oxygen in alkaline medium have been established.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 97104 ISSN: 1026-1265/1997
Mechanical Properties of CaCO3 Filled Natural
Hanafi Ismail and T.A. Ruhaizat
School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
The effect of palm oil fatty acid on curing characteristics and mechanical properties of calcium carbonate filled natural rubber compounds has been studied. Results show that the scorch time and t90 increase with increasing concentration of palm oil fatty acid, while the MHR‑ML (maximum torque - minimum torque) passes through a maximum value and decreases with acid concentration. Mechanical properties viz. tensile modulus, hardness, tensile strength and tear strength also follow the similar trend as MHR‑ML. Reversion studies indicate that incorporation of palm oil fatty acid improves the resistance to reversion of the natural rubber compounds.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 105112 ISSN: 1026-1265/1997
Cross‑linking of Some Copolymers of Tetrafluoroethylene
Through Urethane Bridge by Diisocyanate Reagents;
Kinetics of the Addition Reaction
A. Banihashemi and H. Tajik
Department of Chemistry, Shiraz University, Shiraz, I.R. Iran
An experimental kinetic study of the addition reaction between hydroxyl groups of some copolymers of poly(tetrafluoroethylene‑co‑vinyl alcohol) and isocyanate groups as cross‑linking agents has been conducted. The kinetics of the cross‑linking reaction and the extent of reaction are followed and monitored by infra‑red spectroscopy. It is found that the reaction follows a simple second order kinetics until an extent of reaction of 80% and the gel point of 85‑90% are reached. For conversion above the gel point, a negative deviation from the second‑order kinetics is observed.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 113119 ISSN: 1026-1265/1997
M.A. Semsarzadeh and A. Molaeei
Polymer Group, Chemical Engineering Department, Tarbiat Modarres University, Tehran, I.R. Iran
Polyacrylonitrile films are prepared from the polymer and dimethylformamide (DMF). The thermal treatment of the PAN film like the fibre is considered as an important step in the formation of the ladder polymer structure. The kinetics and thermodynamic studies of the PAN films indicated that the peak temperatures and the enthalpies of the reactions are lower than the PAN fibres. The properties of PAN films and fibres are studied on the basis of CN groups dipole moment and coupling, and their energetics of the reaction with potassium permanganate catalyst and other additives like acetic acid are also determined.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 121126 ISSN: 1026-1265/1997
A. Zarringhalam1‑Moghaddam, M.R. Rezaie1 and M. Mehrabzadeh2
(1) Department of Chemical Engineering, Tarbiat Modrres University, Tehran, I.R. Iran
(2) Polymer Research Center of Iran, Tehran, I.R. Iran
The combustion of a typical thermoplastic polymer, polypropylene mixed with three additive fire retardants, magnesium hydroxide, aluminium hydroxide and antimony trioxide, was assessed in a cone calorimeter. It is found that the increased Mg(OH)2 content in polypropylene, further increases the ignition time and reduces the heat release rate. Its effect on smoke density is found to be somewhat different, when present at lower percentages it increases the smoke density of fire effluents.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 127133 ISSN: 1026-1265/1997
Studies on Latex Stage Carbon Black Masterbatching of NR and
its Blend with SBR
L. Jose1, R. Joseph1 and M. S. Joseph2
(1) Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology, Cochin, India
(2) Rubber Research Institute of India, Kottayam, Kerala, India
Carbon black is incorporated in natural rubber latex in the presence of polyethylene glycol. The dispersion of carbon black in the vulcanizates is analyzed using Polaroid Mp4 land camera. The mechanical properties of the carbon black masterbatched NR/SBR blend is compared with that of conventional NR/SBR blend before and after ageing. The resilience, flex resistance and hardness are found to be superior for N‑LCM/SBR compounds. The compression set and abrasion resistance are comparable for both types of blends. The processability and die swell of these blends at different shear rates are also compared.
Iranian Polymer Journal / Volume 6 Number 2 (1997) 135143 ISSN: 1026-1265/1997
Chemistry Department, Gilan Unieversity, Rasht, I.R. Iran
To develop a biomaterial with high biocompatibility, one must take into consideration both bulk and surface properties of the material which is to be synthesized. In an attempt to produce a deposit resistant material, a group of copolymeric hydrogels, especially those of interest in contact lens industry, are synthesized and their resistance to protein spoliation is measured. Poly(2‑hydroxyethylmethacrylate) known as poly(HEMA) has a number of limitations as a biomaterial, which is illustrated in its use as soft contact lenses where, even though it is found to be mechanically adequate, ocular incompatibility is observed leading ultimately to the formation of "white spot deposits" on the lens surface. Hydrogels synthesized during this study are polyethylene oxide modified poly(HEMA) based gels. The amount of protein adsorbed on these hydrogels is calculated by measuring the UV absorbance against a blank of the same hydrogel. The cell culture studies are also examined by other members in the group and the amount of protein absorbed on each hydrogel is calculated.