Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 82–87                                                        ISSN: 1017-6020/1994

 

 

Poly(vinylpyridine) Supported Versus Unsupported Ferric

 

Dichromate in Oxidation of Different Organic Compounds

 

B. Tamami, H. Firouzabadi, M. Mansour Lakouraj and A.R. Mahdavian

Chemistry Department, Shiraz University, Shiraz, I.R. Iran

 

ABSTRACT

 

Ferric dichromate and crosslinked polymer of 2‑ and 4‑ vinylpyridine supported ferric dichromates are prepared and used effectively as new chromium (\/I) reagents for oxidation of different organic compounds such as benzylic and allylic alcohols, aliphatic primary and secondary alcohols, aromatic hydrocarbons, olefinic and acetylinic double bonds, thiols, oximes and ketals. Unsupported ferric dichromate is more efficient. The polymer supported ferric dichromate reagents are milder, easier to handle, more selective, non-hygroscopic, regenerable and environmentally safer to use. These polymeric oxidizing agents are compared with a few other reported polymer supported chromium (VI) reagents.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 89–93                                                        ISSN: 1017-6020/1994

 

 

Kinetic Study of the Alkylation of p‑Cresol with Isobutylene to

 

Produce BHT Stabilizer for Polymer Materials

 

M.T. Khorasani and G.R. Bakhshandeh

Polymer Research Center, Tehran, I.R. Iran

N. Sharifee and M.H. Rafiée Fanood

Chemistry Department, Tehran University, Tehran, I.R. Iran

 

ABSTRACT

 

The alkylation of p‑cresol with isobutylene gas and oleum as a catalyst is studied at 75 °C in a semibatch reactor. Alkylation is carried out at isothermal conditions. For the study of the kinetic rate, a small amount of the crude products at different times during reaction is removed from the reactor and concentrations are determined by gas ‑ liquid chromatography. Results indicate that the rate of reaction depends only on the volume of p‑cresol, hence, it is infinitely slow and the reaction of p‑cresol with isobutylene at constant concentration of isobutylene is first order multiple series‑parallel. The final equation obtained, which shows that the reaction is independent of reactor height, depends only on the pressure of isobutylene gas, Henry's law constant and duration of reaction.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 95–103                                                      ISSN: 1017-6020/1994

 

 

Obtaining Poly(dimethylsiloxane)‑a, w‑Diols Using the

 

Heterogeneous Catalysis: The Optimization of the

 

Reaction Conditions

 

M. Marcu, M. Siminonescu, M. Cazacu and S. Lazarescu

Petru Poni Institute of Macromolecular Chemistry, Iassi, Romania

C. Ibanescu

Macromolecular Department, Polytechnic Institute of Iassi, Iassi, Romania

 

ABSTRACT

 

Cationic heterogeneous polymerization of a mixture of dimethylcyclosiloxanes is studied, with the aim to evaluate the influence of different factors (temperature, reaction time, the amount of catalyst and water) on the monomers conversion and on the molecular weight of the obtained polymer. A second order, central, composite, rotatable design is used in order to carry out the experiments. The experimental results are processed on a PC‑AT computer in order to obtain the regression equations or the response surfaces for the studied properties. This program allows the study of the possibilities of the process optimization.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 105–114                                                    ISSN: 1017-6020/1994

 

 

"Spacer" Modified Polymer Bonded Metal Chelating Ligands

 

M. Hojjatie, M. Valiente, X. Ribas and H. Freiser

Strategic Metals Recovery Research Facility, Department of Chemistry, University of Arizona, Tucson, AZ, USA

 

ABSTRACT

 

The effect of hydrophobic polymethylene and hydrophilic polyoxyethylene "spacer" groups between the linear polystyrene backbone and acidic phosphorus ligands in chelating polymers on metal absorption rates is studied. A considerable increase in the rate of metal uptake is observed as the length of the spacer is increased. Hydrophilic spacer groups such as oxyethylene and oxypropylene were more effective than the hydrophobic spacers. The study includes the synthesis and characterization of the resins by their acidic behaviour, elemental analysis and copper ion loading capacity.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 115–119                                                    ISSN: 1017-6020/1994

 

 

Swelling and Crosslink Density Measurements for Hydrogels

 

H. Omidian, S.A. Hashemi, F. Askari and S. Nafisi

Polymer Research Center of Iran, Tehran, I.R. Iran

 

ABSTRACT

 

The important physical properties of hydrogels depend on the precise structure of the polymer network. Of key importance is equilibrium swelling capacity. Molecular theories of rubber elasticity describe with varying accuracy the relationship between the molecular structure of a crosslinked polymer and the amount of swelling. In this article some theoretical aspects are presented and experimental results obtained from swelling measurements are reported.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 121–132                                                    ISSN: 1017-6020/1994

 

 

New Poly(vinyl chloride)‑Based Blends:

 

Aspects of Processability (Part I)

 

M. Rusu

Department of Macromolecules, Polytechnic University of Jassy, Romania

M. Dan Bucevschi

Department of Leather and Substitutes, Polytechnic University of Jassy, Romania

F. Petraru and L. Gramescu

S.C. Cerproplast S.A., Jassy, Romania

 

ABSTRACT

 

The concurrent influence of the nature and ratio of some impact modifiers, of the ratio of processing aid and of the carbon black on the main parameters characterizing the Brabender plastogram of some new rigid poly(vinyl chloride) ‑ based compounds is studied.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 133 –139                                                   ISSN: 1017-6020/1994

 

 

Simulation of Post‑Cure Inflation Process of Tires (Part II)-

 

Application of Stress/Strain/Temperature Tire Cord:

 

Mastercurves for Passenger Tire

 

M. Samadi

The Iran Tyre Manufacturing Company, Tehran, I.R. Iran

 

ABSTRACT

 

In the second part of this article tire cord stress/strain mastercurves are employed, and the process of post‑cure inflation for a bias tire size 560‑13 is simulated. The simulation has been done to verify the effect of temperature and pressure on the tire dimension and its performance. To this end the behaviour of the tire in shaping stage and in the post-cure process is analyzed and with the help of the exerted strain on a cord in each stage the optimized pressure of the post-cure is determined. To crosscheck the result, actual cured tires are post‑cured under different internal pressures and the observed strains in the tire cords are compared with the calculated results obtained from the simulation process.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 141–148                                                    ISSN: 1017-6020/1994

 

 

Dibenzyl Structures on the Macromolecular Chain‑v.

 

Polyquinazolinediones and Polybenzimidazoles

 

E. Scortanu, A. Caraculacu G. Caraculacu

“Petru Poni” Institute of Macromolecular Chemistry, Jassy, Romania

 

ABSTRACT

 

Polyquinazolinediones and polybenzimidazoles with dibenzyl structure on the macromolecular chain are synthesized. 4,4'‑2,4'‑Dibenzyldiisocyanate and, respective, 3,3',4,4'‑dibenzyl tetramine are used as monomers for the polymer syntheses. Thermogravimetric, IR spectroscopy and elemental analyses of these polymers are determined.

 


Iranian Journal of Polymer Science and Technology / Volume 3 Number 2 (1994) 149–158                                                    ISSN: 1017-6020/1994

 

 

Exact Determination of the Critical Exponents of Kinetic Self‑

 

Avoiding Random Walks on Four Simplex Fractals (Part II)

 

M.A. Jafarizadeh and S.K. Seyed‑Yagoobi

 

ABSTRACT

 

By defining some of the walks differently from those given in reference [1], we derive the critical exponents n and m for the kinetic self‑avoiding walk in three dimensions and show that the results agree with those of [1].