Iranian Polymer Journal / Volume 5 Number 1 (1996) 4–15 ISSN: 1026-1265/1996

The Influence of Impurity Particles on the Mechanical

Properties of Unreinforced and Short Fibre

Reinforced Thermoplastic Mouldings

A. Zadhoush and M. J. Bevis

Wolfson Center for Materials Processing, Brunel University, Uxbridge, Middlesex

ABSTRACT

Whatever may be the reason for the presence of impurity particles, they are likely to have some influence on the mechanical properties and it is not safe to assume that the data obtained on samples of the particle‑free material can be used for design purposes. The type and amount of added particles, the shape and size of particles are also important in determining the failure behaviour. Based on the mechanical testing results and fractographic evidence presented in this work, several observations and conclusions about the influence of impurity particles on short- and long-term mechanical properties in short fibre reinforced thermoplastics may be noted. Unreinforced materials are more prone to failure due to impurity particles than short fibre reinforced plastics (due to the mechanism of the reinforcement of fibres).

Iranian Polymer Journal / Volume 5 Number 1 (1996) 16–22 ISSN: 1026-1265/1996

Thermal Cyclodehydration of Polyamic Acid Initiated

by UV‑Irradiation

A. Toirov and K. Tashrifov

Umarov Physical-Technical Institute, Tajik Academy of Science, Dushanbe, Tajikistan

ABSTRACT

The use of mass‑spectrometry, IR‑spectrometry, electron‑paramagnetic resonance, mechanical and theoretical methods and the influence of preliminary UV‑irradiation on solid phase thermal cyclodehydration of polyamic acid based on pyromellitic dianhydride and 4,4´‑diaminodiphenyl ether are studied. Optimum condition of thermal cyclodehydration of polyamic acid using UV‑irradiation has been found to give the high degree of turn. The mechanism of solid phase photoinitiated thermal cyclodehydration of polyamic acid is proposed. The theoretical calculation of the duration rate of imidization of polyamic acid photothermal cyclodehydration is also carried out.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 24–29 ISSN: 1026-1265/1996

Effect of Reactant Ratios on Gel Point of Sulphonated Melamine-

Formaldehyde Superplasticizer

N. Goudarzian¹, A. Rabiee¹ and H. Hamidi²

(1) Polymer Research Center of Iran, P.O. Box 14185/458, Tehran, I.R. Iran

(2) Islamic Azad University, Tehran South Unit, P.O. Box 11365/4435, Tehran, I.R. Iran

ABSTRACT

The effect of molar ratios of reactants on physical properties of sulphonated melamine‑formaldehyde (a superplasticizer) prepared under different reaction conditions is studied. It is found that the more stable products are affected slightly by melamine to formaldehyde (M/F) and melamine to sodium metabisulphite (M/S) molar ratio. In addition, the pH, temperature and time are the main controlling factors for product stability.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 30–41 ISSN: 1026-1265/1996

A Transient Finite Element Model of Mixing of Rubber

Compounds in a Banbury Mixer

M.H.R. Ghoreishy

Polymer Research Center of Iran, P.O. Box 14185/515, Tehran, I.R. Iran

ABSTRACT

The aim of this paper is to develop a mathematical model for the simulation of the flow of elastomeric materials inside a typical Banbury mixer. The model combines the non‑Newtonian behaviour of rubber compound with non‑isothermal flow regime in a transient condition. The set of the governing equations are solved using the finite element method. The momentum equations are solved using continuous penalty method and the energy equation is solved employing the Galerkin method. A streamline unwinding technique is used in the solution scheme of the energy equation to provide convergent and stable results for high Peclet number flow. The solution of the transient equations is performed using implicit q time stepping method. The overall solution strategy is based on the de‑coupling of the flow and energy equation and use of the Picard iterative scheme. The results of the simulation include the velocity, pressure and temperature distributions and the variation of these parameters with time. Comparison of these results with the available experimental data confirms the general validity of the development model.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 42–49 ISSN: 1026-1265/1996

4‑Nitrophenyl Methacrylate‑Glycidyl Methacrylate Copolymers

Synthesis, Characterization and Reactivity Ratios

S. Thamizharasi, P. Gnanasundaram, A. Venkata Rami Reddy, and K Venkata Rao

Department of Chemical Engineering, Alagappa College of technology, Anna University Guindy, Maddras 600 025, India

ABSTRACT

4‑Nitrophenyl methacrylate is prepared, characterized by IR and NMR spectroscopic techniques and polymerized in methyl- ethyl ketone using benzoyl peroxide as initiator. Copolymers of 4‑nitrophenyl methacrylate with glycidyl methacrylate are prepared in methyl ethyl ketone at 65 ºC using benzoyl peroxide as initiator. The homopolymer and the copolymers are characterized by IR, ¹H and ¹³C NMR. Their compositions are determined by ¹H NMR analysis. The monomer reactivity ratios are determined by the application of conventional linearization methods of Finmann‑Ross and Kelen‑Tϋdos. The molecular weights are determined by gel permeation chromatography. The thermal behaviour of the polymers is studied by TGA.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 50–55 ISSN: 1026-1265/1996

Radiational Graft Polymerization of Hexenes on Polystyrene

R.M. Aliguliyev, E.A.M. Efendiyev, A.E. Portiynski and R.Z. Gadjiyev

AZNIIOLEFIN, Baku, Azerbaijan Republic

ABSTRACT

The graft polymerization of isomeric hexenes on polystyrene is carried out in order to create an electrical insulation material with improved operation characteristics. Reactions are conducted by radiational‑chemical methods, applying g‑radiation and accelerated electrons. The mechanical, thermal, structural and dielectric characteristics of modified polystyrene are investigated. The grafting is proved to be most effective with application of 4‑methyl‑1‑pentene. Kinds and dosage of radiation are optimized. The described method allows improvement of dielectric losses, heat resistance and thermostability of polystyrene.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 56–59 ISSN: 1026-1265/1996

Preparation and Properties of Polyurethane Foams from Toluene

Diisocyanate and Mixtures of Castor Oil and Polyol

D.S. Ogunniyi¹ and W.R.O. Fakayejo¹ and A. Ola²

(1) Department of Chemistry, University of Ilorin, Ilorin, Nigeria

(2) Vitafoam Nigeria Plc, Ikeja, Lagos, Nigeria

ABSTRACT

Castor oil is obtained by extracting the crushed seeds in a soxhlet extractor. The oil is characterized and used wholly in the preparation of polyurethane foam. Additionally, some polyurethane foams are prepared from mixtures of castor oil and polyol (hydroxy‑terminated polyether). The mechanical properties of the foams are comparable to that in which 100% polyol is used. The use of 100% castor oil in foam synthesis produces a semi‑rigid material that can be used in various applications.

Iranian Polymer Journal / Volume 5 Number 1 (1996) 60–64 ISSN: 1026-1265/1996

Study of Paracetamol Release from a Castor Oil Based

Copolyester Matrix

M.N.V. Ravi Kumar, G. Madhava Reddy and P. Kumar Dutta

Department of Applied Chemistry, Shri G.S. Institute of Science and Technology, Indore, (M.P.) 452 003, India

ABSTRACT

The copolyester prepared from the monomers is mechanically stable and it undergoes slow hydrolytic degradation under physiological condition. Paracetamol is incorporated in the polymer during its synthesis and the release of the drug from the polymer is studied by UV spectrophotometer. After an initial boost release for the first day, the rate is gradually decreased.