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Effects of State Change of Liquid Crystalline Polymer on Dynamic Visco-elasticity of its Blends with Polyethylene-terephthalate
Appl. Rheol. 17:6 (2007) 64510 (7 pages) ►
The dynamic viscoelastic properties of liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) blends were studied at two different temperatures: 265 oC at which LCP was in solid state and 285 oC at which LCP was in molten state. The PET was in molten state at both the temperatures. The storage modulus, G', loss modulus, G'', dynamic viscosity, η', of blends with different compositions were evaluated and compared. The morphology of these samples was studied using scanning electron microscope, which exhibited composition dependency. A maxima was observed in the viscosity versus composition plot corresponding to 90/10 LCP/PET blend at 285oC. The G' versus G'' plots demonstrated the composition dependency of LCP/PET blends.► Cite this publication as follows:
Hashmi SAR, Kitano T: Effects of State Change of Liquid Crystalline Polymer on Dynamic Visco-elasticity of its Blends with Polyethylene-terephthalate, Appl. Rheol. 17 (2007) 64510.
S.A.R. Hashmi, T. Kitano
Rheology of LCP/PET Blends at Solid and Molten States of LCP
Appl. Rheol. 16:3 (2006) 152-160 ►
Liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) were blended in an elastic melt extruder to make samples having different volume fractions of constituent polymers. Shear stress, shear viscosity, first normal stress difference at different shear rates under steady state conditions of these blends were evaluated at two different temperatures 265 and 285°C. The LCP was in solid state at 265° C and in melt state at 285°C and was dispersed in molten matrix of PET at both temperatures. Shear viscosity of blend increased with addition of LCP in PET matrix. A maxima was observed in viscosity versus composition plot. Blends containing more than 50 vol. % of LCP in the blend show higher viscosity as compared to the constituent polymers. First normal stress difference, N1, increased with LCP content in the blend at 285°C when ploted against shear stress whereas at 265°C this trend was opposite. The increased value of N1 with shear rate was explained assuming a tendency of asymmetric particles to rotate under velocity gradient of suspending medium. At 285°C N1 varied with shear stress in two stages. First stage was characterized with high sensitivity of N1 with shear stress, which reduced in second stage on plastic deformation of LCP droplets.► Cite this publication as follows:
Hashmi SAR, Kitano T: Rheology of LCP/PET Blends at Solid and Molten States of LCP, Appl. Rheol. 16 (2006) 152.
T. Kitano, S.A.R. Hashmi, N. Chand
Dynamic viscoelastic properties of organic/inorganic fibres reinforced LLDPE composites in molten state
Appl. Rheol. 11:5 (2001) 258-263 ►
Dynamic rheological parameters such as storage modulus, G, loss modulus, G, and dynamic viscosity, h, at 200°C were studied for Kevlar fibres, glass fibres and their hybrids reinforced linear low density polyethylene (LLDPE). Parallel plate rheometer was employed for these tests. G, G and h increased with the increased reinforcement and angular frequency, w. Two sets of reinforcement, 10 and 20 vol.% of fibres are used in LLDPE. The composition of fibres in hybrid composites was varied. The replacement of glass fibres with Kevlar increases the values of G, G and h. The values of these rheological parameters also increased with the thickness of the composite. This increase was associated with the decreased average orientation of fibres present in the composite. The effects of the change in strain amplitude on G and G is also studied and reported here.► Cite this publication as follows:
Kitano T, Hashmi SAR, Chand N: Dynamic viscoelastic properties of organic/inorganic fibres reinforced LLDPE composites in molten state, Appl. Rheol. 11 (2001) 258.
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