Iranian Journal of Polymer Science and Technology / Volume 1 Number2 (1992) 56–61 ISSN: 1017-6020/1992
Alkaline Hydrolysis of Polyester Fibers - Structural Effects
M. Haghighatkish and M. Yousefi
Textile Department, Amir Kabir University of Technology, Tehran, I.R. Iran
Partially oriented and fully drawn poly(ethyleneterephthalate) (PET) fibers were treated with aqueous solution of 10% sodium hydroxide at 30 °C. The weight loss, density, diameters and birefringence of fibers were measured. X‑Ray diffraction studies were carried out and SEM photomicrographs of fibers were obtained. Both yarn types showed progressive weight loss and reduction of diameters with increasing time of alkaline treatment. There were no changes in orientation and crystallinity of fibers.
Surface morphology differed between partially oriented and fully drawn fibers. It is concluded that the reaction occurs preferentially in the region of low structural order on the surface of fibers.
Iranian Journal of Polymer Science and Technology / Volume 1 Number 2 (1992) 62–68 ISSN: 1017-6020/1992
Preparation and Activity of Sterically Hindered Phenol
Antioxidants for NR and SBR
M.T. Khorasani and G.R. Bakhshandeh
Polymer Research Center of Iran, Tehran, I.R. Iran
Antioxidants of 2[2, 2, 3, 4, 5, 5-hexa methyl hexyl]‑6‑tertbutyl‑4‑methyl phenol and 2[2, 2, 3, 4, 5, 5-hexa methyl hexyl]‑4,6, di‑tert butyl phenol are synthesized. The efficiency of these antioxidants and 2,6‑di‑tert butyl‑p‑cresol (BHT) and 2, 4, 6‑tri‑tert butyl phenol (TTP) and styrenated‑phenol (SP), have been studied by comparing physical and thermal properties (e.g, tensile strength elongation at break, differential scanning calorimetry) of the related non‑black NR and SBR. The work described in this paper shows that the activity depends on the substituted groups in the ortho and para position on phenol structures and the molecular weight of the antioxidants.
Iranian Journal of Polymer Science and Technology / Volume 1 Number 2 (1992) 69–77 ISSN: 1017-6020/1992
Small-Angle Light Scattering for the Characterization of
Starches and Spherulitic Polymer Studies
S.A. Hashemi and G.J.L. Griffin
Department of Material Technology, Brunel University, Uxbridge, UB8, 3PH, UK
The observed small‑angle light scattering (SALS) from spherulites is described by the theory of an anisotropic spheroid in an isotropic medium. The theory and application of small‑angle light scattering was reviewed because of its value as a technique for the characterization of starches and spherulitic polymer studies. On the basis of SALS theory the experimental arrangement is established and photometric measurement on starches is presented. Total number of 112 taro starches were characterized in terms of average particle size ranging from 3‑50 microns in order to establish the size/effect relationship in starch polymer composite. Out of the total number of starches mentioned, the results of four taros are presented in our report.
Iranian Journal of Polymer Science and Technology / Volume 1 Number 2 (1992) 78–83 ISSN: 1017-6020/1992
Stress Analysis in Elastic Bending Beams and Thick
Polymer Research Center of Iran, Tehran, I.R. Iran
For materials selection, proper design and manufacturing of polymer products used in structural and other engineering applications, rendering stress analysis is a matter of prime importance. The first part of this work is devoted to a simple manipulation of bending behavior, as the main deformation mode in beams, while in the second part expressions for the stresses in thick hollow cylinders under simultaneous internal and external pressure loading are determined. The two topics dealt with are of particular interest in connection with polymeric materials. Although the constitutive equations are derived pertaining to linear elastic materials, they can describe many aspects of small strain behavior of rigid polymers which can be utilized as structural materials.
Iranian Journal of Polymer Science and Technology / Volume 1 Number 2 (1992) 84–110 ISSN: 1017-6020/1992
Trends in Polyurethanes Elastomer Technology
Institute of Polymer Technology and Materials Engineering, Loughborough University of Technology
Loughborough, Leicestershire, LE11 3TU, UK
Polyurethane elastomers (PUs), as a unique material class and occupying special place in the materials‑properties spectrum, are defined in terms of their physical property and chemical structure relationships. Their traditional application fields are defined followed by the great upthrust of PUs into new fields in the aerospace, surface coatings and automotive industries. New polyols, copolyesters, fluorinated polyols, amine terminated polyols and their influence on new PU elastomers are covered, together with the part played by the introduction of aliphatic diisocyanates. These new synthesis reagents together with safer chain extenders based on aromatic diols and non-carcinogenic diamines have led to a renaissance in speciality PUs. Thus in later years advances in PU science have produced new products such as: UV light curable PU systems, now important industrially; and also water vapour permeable PUs introduce a new dimension to this elastomer technology. Biocompatible PUs are established in medicine and transparent PU are being important in the aircraft, automobile and military areas due to their clarity, strength and high impact resistance. The scientific understanding of property‑structure relationships that has made these application advances possible are being discussed in this paper.