Iranian Polymer Journal / Volume 6 Number 3 (1997) 151157 ISSN: 1026-1265/1997
M. Shahrokhi1 and M. Parvazinia2
(1) Department of Chemical Engineering, Sharif University of Technology, Tehran, I.R. Iran
(2) Polymer Research Center of Iran, Tehran, I.R. Iran
A major characteristic of polymerization reactors is their complex nonlinear behaviour. Due to this nonlinear nature, control of polymerization reactors has always been a challenging task. In this article the performances of three adaptive control schemes, namely, self‑tuning control(STC), adaptive internal model control (AIMC) and adaptive robust generic model control (ARGMC) are compared through simulation studies. The temperature control of polymerization of methyl methacrylate (MMA), which is highly exothermic, is chosen for simulation. Simulation results show that all three schemes can control the process but the best performance belongs to STC scheme.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 159167 ISSN: 1026-1265/1997
Stable, and Efficient Reducing Agent in Organic Synthesis
B. Tamami, M. Mansour Lakoraj and H. Yeganeh
Department of Chemistry, Shiraz University, Shiraz, I.R. Iran
The unstable chloroaluminum borohydride is stabilized on polyvinylpyridine, and it is used as an efficient and regenerable polymer supported transition‑metal borohydride reagent for reduction of variety of organic compounds such as, aldehydes, ketones, acid chlorides, epoxides and azides. The reagent is unable to reduce, esters, amides, oximes, and nitro compounds.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 169175 ISSN: 1026-1265/1997
onto Natural Biopolymer
G. Annadurai and M.R.V. Krishnan
Department of Chemical Engineering, Alagappa College of Technology, Anna University, Madras-600 025, India
We have investigated the possibility of using chitosan which has amino groups, and therefore, has the advantage of more adsorption capacity and much easier desorption. Chitosan is produced by deacetylation of chitin which is a natural biopolymer extracted from the shells of arthropods such as lobsters, shrimps and crabs. In the present work, results for the batch equilibrium of adsorption of reactive dye on chitosan from its aqueous solution at different particle sizes and temperatures have been reported. The adsorption isotherms are found to be described by Langmuir, Freundlich and Redlich‑Peterson types of equations. From the adsorption isotherms, the adsorption capacity, energy of adsorption, number of layers and the rate constants are evaluated. The rate of adsorption on chitosan is found to be dictated by variables such as temperature and particle size at a fixed pH. Differential scanning calorimeter signals obtained with dye adsorbed on chitosan samples indicate that the dye is chemisorbed on chitosan; and the value of DH is 23.685 J/g in the temperature range of 120‑180 ºC.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 177183 ISSN: 1026-1265/1997
Chemical Engineering Department, Razi University, Kermanshah, I.R. Iran
The critical fluxes for two deferent colloidal silica suspensions are measured. Electron microscopy is used as a tool for critical flux mechanism investigation. Above the critical flux, deposition of silica particles or formation of a cake is evident. This is usually accompanied by a drop in delivered flux. For fluxes below the critical value there is no cake formation. However, particles may deposit on the membrane surface for longer runs, or when the flux is marginally below the critical value. This is in accordance with the model of having a concentrated polarized layer with intermittent pore blockage or obstruction without permanent fouling. During the intermittent blocking, particles have more chance to settle on the membrane surface and form a small deposition. In this case the deposit has a flowing nature rather than a stagnant structure. Another explanation for small deposition, while flux remains below the critical value, is based on differences between the local and average fluxes. The measured flux which is an average of all local fluxes is below the critical value. However, the local fluxes in parts of the membrane may be higher than the critical flux, which may result in formation of small cakes in various locations on the membrane surface.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 185194 ISSN: 1026-1265/1997
Algorithm (C 4.5): A Case Study of a Conducting
Polymer Ion Detector
A. Talaie1, J.A. Romagnoli1, N. Esmaili2 and T. Taguchi3
(1) Chemical Engineering Department, The University of Sydney, Sydney, N.S.W., Australia, 2006
(2) Artificial Intelligence Department, The University of New South Wales, Kensington, N.S.W., Australia, 2033
(3) Osaka National Research Institute, Midorigaoka, Ikeda, Osaka 563, Japan
The development of an on‑line computer based classification system for the automatic detection of different existing in different solutions, is addressed in this study. Three different parameters (current, mass, and resistance) are collected simultaneously. Then these laboratory measurements are used by an algorithm software as a logged data file, resulting in to inducing a decision tree. Later, a systematic software is designed based on the rules derived from this decision tree, to recognize the type of unknown solution used in the experiment. This is a new approach to data acquisition in chemical industries involving conducting polymers.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 195203 ISSN: 1026-1265/1997
H.A. Mehrabi and J. Bowman
Physics Department, Brunel University, Uxbridge, Middlesex, UK
Fatigue and squeeze tests have been undertaken to investigate if electrofusion couplers can be used to joint cross‑linked polyethylene pipes. Two types of polyethylene pipes, each with 63 mm outside diameter and 5.8 mm wall thickness, are irradiated to various doses (5‑200 kGy) and are joined by electrofusion method. According to experimental results, the gel content varies with dose. All joints have passed the sqeeze test, regardless of the gel content of the pipes radiation. All joints have also passed 170 h of fatigue loading which is an indication of a reasonable joint strength. The results with cross‑linked PE pipe further indicate the flexibility of electrofusion jointing, showing again that the process is able to joint a very wide range of polyethylene resins. Electrofusion welding necessitates only a few manual actions from the operator. However, it is essential that these are carried out carefully. The key to success is the joints preparation.
Iranian Polymer Journal / Volume 6 Number 3 (1997) 205219 ISSN: 1026-1265/1997
Applied to Nylon and Cotton by After‑treatment
with Synthetic Tanning Agents
Textile Department, Isfahan University of Technology, Isfahan 84156, I.R. Iran
To examine the effect of after‑treatment with synthetic tanning agents (syntans)a range of suitable compounds are synthesized and applied to undyed nylon 6,6 and cotton. Syntan action is measured by estimation of restraining action. Therefore, a range of simple model hydroxy compounds are used. Effective syntans for nylon is appeared to be based on condensed phenolic rings with a water solubilizing group SO3H present. Their chemical structures are believed to be similar to an acid dye except they are colourless (or should be) and have high molecular weights and more linear structures. At first, studies on cotton condensates from naphthols and substituted phenols and formaldehyde are undertaken. The adsorption of direct dyes by cotton so treated is not reduced although in some cases these compounds are readily absorbed by cotton. One of the objectives of this work is to compare the effect of syntans on the dyeing properties of cotton. Therefore, a syntan containing stilbene groups so to give higher affinity towards cellulosic fibres is tested, but the restraining action of dye diffusion is not still so significant.