Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 311 ISSN: 1017-6020/1993
Dynamic Vulcanization- An Accessible Way to Thermoplastic
Research Institute for Rubber and Plastics Processing, Bucharest, Romania
Technical and economical reasons relating to the increased performance level, greater productivity, and the economic use of materials and energy are stimulating the industry toward an accelerated increase in the use of thermoplastic elastomers. The thermoplastic elastomers obtained by mixing classical elastomers and plastomers form a class of materials with the largest prospect for commercial application. These materials are obtained by mixing rubbers with thermoplastics and realizing the crosslinking of the elastomer phase during a mixing operation frequently referred to as "dynamic vulcanization". Here the parameters of mixing and the vulcanization operation as well as the properties of the resulting thermoplastic elastomers for non‑polar polymers are reviewed.
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 1218 ISSN: 1017-6020/1993
Polypropylene/NBR Thermoplastic Elastomers Mechanics,
Rheology and Crystallinity
A.A. Katbab, M.S. Anaraki, and H. Nazokdast
Polymer Engineering Department, Amir Kabir University, Tehran, I.R. Iran
Thermoplastic elastomers based on isotactic polypropylene (PP) and acrylonitrile‑butadiene rubber are prepared. Effects of compositional variables on blend dynamic properties (tand and G) and crystallinity are studied using DMTA and DSC, respectively. Dependence of apparent viscosity (ma) and flow behaviour index (n) upon the blend composition and shear rate are also investigated. Tensile characteristics of blends are examined. AII results show that these two polymers are not compatible from the molecular point of view. Storage modulus increased and loss tangent decreased with an increase of PP content. At all compositions, pseudoplastic behaviour is observed and blend viscosity does not obey the linear additive law. Tensile strength of blends is also found to be a non‑additive function of the NBR and PP strength.
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 1925 ISSN: 1017-6020/1993
Polycondensation of Diphenyl-2,2-diiodobiphenyl-4,4-diglyoxal
with Different Di- and Tetra-Aminocompounds
A. Banihashemi, M. Amiri and B. Haghighi
Department of Chemistry, Faculty of Sciences, Shiraz University, Shiraz, I.R. Iran
Several potentially thermostable polyquinoxalines are prepared by condensation of 2, 2‑diiodobiphenyl‑4,4‑diglyoxal dihydrate (1) with several aromatic tetraamine compounds (Xl‑XIII). Polymerizations are carried out either in hexamethylphosphoric triamide solution or as a melt condensation at 300350 °C under nitrogen atmosphere. Some model compounds are also prepared from diglyoxal (I) and diaminocompounds (VIII‑X). All of them show the formation of a quinoxaline ring. The elemental analysis is consistent with the proposed structures. Melting points of all the synthesized polymers are over 340 °C with high stability at elevated temperatures.
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 2630 ISSN: 1017-6020/1993
Copolymers XIII. Study on Acrylonitrile Terpolymerization with
Vinyl-Acetate and Nonyl-Phenol-Oligoethoxylate Acrylate
M. Nicu, M. Lungu and D. Asandei,
Department of Macromolecules, Polytechnical Institute of Jassy, Romania
Department of Chemical Engineering, Polytechnical Institute of Jassy, Romania
Department of Physical Chemistry, Polytechnical Institute of Jassy, Romania
The reaction between acrylonitrile (AN), vinyl‑acetate (VA) and nonyl‑phenol‑oligoethoxylate acrylate (FA) initiated by potassium persulfate, K2S2O8 and sodium metabisulfite, Na2S2O5 at 60 °C in aqueous medium is studied. We have ascertained that the reaction is a terpolymerization which takes place after the Alfrey‑Goldfinger terminal model and that the composition and sequences distribution in terpolymers are not significantly influenced by the conversion degree. The terpolymers are formed of long AN chains gathered by monomerical unities arising from the other comonomers.
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 31 36 ISSN: 1017-6020/1993
Kinetics of Polymerization of Acrylamide by Potassium
Bromate/Thiourea Redox Pair in Water/DMF Mixture
U.D.N. Bajpai, A.K. Bajpai and A. Soni
Polymer Research Laboratory, Department of Chemistry, Rani Durgavati Vishwavidyalaya, Jabalpur, India
The kinetics of polymerization of acrylamide initiated by potassium bromate/thiourea redox system is studied at 32±0.2 °C under nitrogen atmosphere in acidic water/DMF medium. The effect of various parameters like monomers, redox components, temperature, DMF and neutral salts is studied in detail. The overall energy of activation is calculated to be 3.76 Kcal/deg.mol. The following rate expression is derived to explain the experimental findings: Rpa[Monomer] [KBrO3] [H+]/[DMF].
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 3743 ISSN: 1017-6020/1993
Pneumatic Tire Modeling by Membrane Method
Rubber Industries Engineering & Research Company, Tehran, I.R. Iran
Tires play important roles in cars performance. Since the early days of their production, many investigators have tried to find the relationship between tires' structural parameters and their performance. It has been established that mathematical methods are the most effective techniques, and are divided into different methods. This paper deals with the thin shell theory from the membrane viewpoint and its related problems of stress analysis are discussed. In further steps, the calculated results of a model for a four ply bias tire (7.0016) are presented and compared with experimental data. It is observed however that although this method is an approximate model and consists of many simplifying assumptions, the calculated results are in good agreement with experimental data.
Iranian Journal of Polymer Science and Technology / Volume 2 Number 1 (1993) 4456 ISSN: 1017-6020/1993
Hydroperoxide Formation and the Effect of Stabilizers on
Integrated Chemiluminescence in the Early Stages of
M. Ghaemi1 and G.A. George2
(1) Institute of Chemistry, University of Mazandaran, Babolsar, I.R. Iran
(2) Department of Chemistry, University of Queensland, Australia
The total chemiluminescence from polypropylene (PP) films heated in an inert atmosphere is a sensitive measurement of the hydroperoxide content in the induction period of photo‑oxidation. The PP films show a very rapid increase in the hydroperoxide content in the early stages of photo‑oxidation which could not be detected by ATR‑IR or XPS analysis. This appears as a peak in all of the films which increases in area with film thickness, indicating it is a bulk property. These are believed to form by the rapid oxidation of the PP in localized zones of high photoinstability. The integrated chemiluminescence is affected by a number of common stabilizers, particularly free radical scavengers. It was found that only the thiodipropionate ester and a 2‑hydroxy benzophenone UV absorber affected the kinetics of hydroperoxide formation and decomposition and increased the induction period as measured by carbonyl index. A hindered triphenyl phosphite produced an immediate increase in integrated chemiluminescence and was a prodegradant unless a hindered phenol was incorporated to inhibit peroxy radical attack on the stabiliser. A commercial hindered piperidine caused a lowering of the chemiluminescence which is consistent with a weak radical scavenging and hydroperoxide decomposing activity of the amine.