Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 156168 ISSN: 1017-6020/1995
Studies of Mechanical Properties, Thermal Behaviour and
Morphology of Polyamide 11 and Nitrile Rubber Blends:
Effect of Rubber and Acrylonitrile Content
M. Mehrabzadeh and R.P. Burford
Department of Polymer Science, The University of New South Wales, P.O. Box 1, Kensington, NSW 2033, Australia
The impact behaviour of polyamide 11 when modified with butadiene-acrylonitrile copolymers ("nitrile rubbers") are studied. The effects of rubber addition concentration and the acrylonitrile content are examined. At higher nitrile contents relatively large amounts of rubber are needed for toughness but this will reduce stiffness and strength. However, low‑nitrile content elastomers enhance toughness, even at rather low (20%) levels. The thermal behaviour of polyamide 11/nitrile rubber blends are studied. Sections of tensile and/or impact test‑pieces are then analyzed by DSC and DMA. These two methods are combined to show trends in Tg, Tm modulus and tan d. The polyamide Tm and Tg decreased and the Tg's of the nitrile rubber increased. These changes indicate partial miscibility between the rubber and the thermoplastic. Similarly, DMA tan d data also reflect polymer miscibility. Changes in modulus at various temperatures are measured for each blend. At a given rubber loading, the lower AN rubber blends give low modulus values at room temperature, correlating with improved impact performance. Phase morphology and mechanism of fracture surface morphology of PA11/NBR blends are studied by scanning electron microscopy (SEM).
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 170179 ISSN: 1017-6020/1995
V. Haddadi‑Asl, R.P. Burford and J.L. Garnett
School of Chemical Engineering and Industrial Chemistry, The University of New South Wales
P.O. Box 1, Kensington, NSW 2033, Australia
Radiation grafting of N‑vinyl‑2‑pyrrolidone (NVP) onto ethylene‑propylene elastomers (EPM rubbers) by the simultaneous method is studied. The present work centers upon gamma radiation induced grafting of N‑vinyl‑2‑pyrrolidone (NVP) onto four different EPM rubbers. Metal based homopolymerization inhibitors including Mohr's salt, Cu(NO3)2 and FeSO4 are evaluated and found to prevent homopolymerization and significantly increase graft yield. Lithium nitrate is also evaluated as a graft promoter. The role of the type of EPM rubber on grafting efficiency for a variety of monomers is investigated, to optimize grafting conditions for each EPM rubber and monomer. The effect of multifunctional acrylic additives including TMPTA, PEGDA and PGTA is also studied. The structures of the resulting grafted EPM rubber are studied by SEM.
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 180196 ISSN: 1017-6020/1995
Flow and Solidification During the Filling of Cold Cavities with
Crystallizing Viscoelastic Polymers
T.D. Papathanasiou1 and M.R. Kamal2
(1) Department of Chemical Engineering and Chemical Technology, Imperial College of Science
Technology and Medicine, London SW7 2BY, UK
(2) Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 2A7, Canada
This article presents a model for the filling of cold cavities with solidifying, semi‑crystalline viscoelastic polymers. Based on this model, prediction on the extent of wall solidification, skin crystallization and pressure drop as functions of processing conditions during filling are presented. The mathematical model considers two‑dimensional creeping flow and three‑dimensional transient heat transfer, coupled with the White‑Metzner viscoelastic constitutive model and the Nakamura non-isothermal crystallization kinetics model. The resulting set of partial differential equation is non‑linear, since the material properties are function of processing conditions. Geometry‑adaptive body fitted curvilinear coordinates are used for the discretization of the flow field and the resulting set of finite difference equations is solved using iterative methods on curvilinear structured meshes. The numerical model is presented in some detail and the obtained solutions are extensively validated by comparison with analytical results and by mesh refinement. Simulation results show that wall solidification during filling is mainly affected by conductive cooling to the mold walls and, to a lesser extent, by convective heating due to polymer melt flow. The level of surface crystallinity at the end of the filling stage depends on the prevailing heat flux conditions. The temperatures at the surface of the cavity during filling are largely unaffected by the fountain flow effect.
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 198208 ISSN: 1017-6020/1995
Chemical Setting of Nylon 6 Multifilament Yarns in Twist and
M. Haghighat Kish and T. Moini
Textile Engineering Department, Amir Kabir University of Technology, Tehran, I.R. Iran
Effects of different solvents on tensile mechanical properties of nylon 6 filament yarns are examined. Treatment with these solvents decreases the yarn strength and increases the breaking elongation. Aqueous solutions of phenol and chlorophenol are used to set the mechanical deformation in twisted yarn and knitted fabrics. Properties of solvents set and heat set yarns are compared. The results are explained with reference to current literature.
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 210216 ISSN: 1017-6020/1995
The Effect of Acrylonitrile Content of Styrene‑Acrylonitrile
Copolymer on Styrene- Acrylonitrile/Styrene‑
Butadiene‑Styrene Alloy System
Jin Kuk Kim
Department of Polymer Engineering, Gyeongsang National University, Chinju, Gyeongnam, Korea, 660-701
As toughening the brittle polymers with the rubber components has been recently drawing attention, the investigation of the characteristics of toughened SAN/SBS polymer blend has been made in this study. The microphotography showed the SBS (styrene‑butadiene‑styrene) domain in the SAN (styrene‑acrylonitrile) matrix. This study concentrates on the effect of acrylonitrile content on the mechanical properties and the optical properties of SAN/SBS alloy system. This paper describes the role of the acrylonitrile (AN) in SAN/SBS by comparing SAN only with SAN/SBS blend.
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 218225 ISSN: 1017-6020/1995
Swelling of Acrylamide‑Tartaric Acid Hydrogels
E. Karadag1, D. Saraydin1 and O. Gόven2
(1) Department of Chemistry, Cumhuriyet University, 58140 Sivas, Turkey
(2) Department of Chemistry, Hacettepe University, Beytepe, 06532 Ankara, Turkey
Acrylamide/tartaric acid hydrogels in the form of rods are prepared by irradiating aqueous solutions of 1 g of acrylamide and varying quantities of tartaric acid between 0‑60 mg in 1 mL of water, with 2.60‑5.71 kGy g‑rays. The influence of dose and relative content of tartaric acid on the swelling properties, diffusional behavior of water, diffusion coefficients and network properties (i.e., number‑average molar mass between crosslinks, crosslink density, number of elastically effective chains, number of repeating units between crosslinks and mesh size) of hydrogel systems is examined. Hydrogels are swelled in the range 700‑1400%, while polyacrylamide hydrogels are swelled in the range 650‑700%. Water diffusion to hydrogels is non‑Fickian type diffusion.
Iranian Journal of Polymer Science and Technology / Volume 4 Number 3 (1995) 226234 ISSN: 1017-6020/1995
Simulation of Stress‑Strain Behaviour of Fibre Reinforced
Cementitious Composites in Flexure
M. Razavi Nouri and J. Morshedian
Polymer Research Centre of Iran, Tehran, I.R. Iran
This work attempts to characterize the stress‑strain behaviour of fibre reinforced cementitious composites in flexure. An analytical model that was originally designed by Fanella to show how the addition of several types of fibres to concrete affects the compressive stress‑strain curves is used here by the authors to reproduce the results of the flexural tests. The validity of the analysis is shown by the close agreement between the prediction of the model and the experimental stress‑strain behaviour of cementitious composites consisting of 1% to 6% volume fractions of two types of polyacrylonitrile (Dolanit 10 & 11) and E‑glass fibres. Nevertheless, it is observed that the simulation brought about by this model cannot always be valid and for orthodox stress‑strain behaviour, for example, in composite samples of 1% volume fraction of Dolanit 11, the shortcoming of the model is clear.