Ultrasonically-aided extrusion of blends of two thermotropic LCPs

Gunes, Kaan; Isayev, A. I.

doi:10.1134/s0965545x10110064

Cited by 7 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Apart from the material viscoelasticity, die geometric structure, and process parameters, the stick-slip effect between the melt and the die was also studied by many researchers. [14][15][16][17] Up to now, some methods such as fluoropolymer, 18 additive, 19 vibration extrusion, 20,21 etc. have been used to improve the stick-slip effect between the melt and the die.…”

Section: Extrusion Formingmentioning

confidence: 99%

See 1 more Smart Citation

Numerical and experimental studies for gas assisted extrusion forming of molten polypropylene

Ren

Huang

Liu

et al. 2015

J of Applied Polymer Sci

View full text Add to dashboard Cite

In this study, the experiments of gas-assisted extrusion (GAE) for molten polypropylene were carried out under different gas pressures, the different extrudate deformations and sharkskin defects of melt were observed. To ascertain the effects of gas on melt extrusion, non-isothermal numerical simulation of GAE based on gas/melt two-phase fluid model was proposed and studied. In the simulations, the melt extruded profile, physical field distributions (velocities, pressure drop, and first normal stress difference) were obtained. Numerical results showed that the deformation degree of melt increased with increasing gas pressure, which was in good agreement with experimental results. It was demonstrated that the influence of gas pressure on the melt extrusion could be well reflected by GAE simulation based on gas/melt two-phase fluid model rather than simplified-GAE (SGAE) based on full-slip wall boundary condition used in the past time. Experimental and numerical results demonstrate that the gas pressure induced first normal stress difference is the main reason of triggering flow behavior changes, extrudate deformations, and sharkskin defects of melt. Therefore, the reasonable controlling of gas pressure is a key in practice of GAE, and the gas layer and its influence should be considered in GAE numerical simulation.

show abstract

Section: Extrusion Formingmentioning

confidence: 99%

“…f n 50 and v s 50 (20) For the thermal boundary of melt and gas exit, the outflow thermal condition is imposed because of unknown temperature in advance.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Numerical and experimental studies for gas assisted extrusion forming of molten polypropylene

Ren

Huang

Liu

et al. 2015

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…6 Later, ultrasonically aided processing was used to prepare various polymer blends, including high-density polyethylene (HDPE)/polystyrene (PS), 7,8 polypropylene (PP)/PS, 9 PP/ethylene propylene diene methylene (EPDM) rubber, [10][11][12][13][14][15][16] PP/natural rubber (NR), 10,11,17 HDPE/NR, 10,11 HDPE/ EPDM, 10,11 HDPE/styrene butadiene rubber (SBR), 10,11 NR/SBR, 10,11 PP/ultrahighmolecular weight polyethylene, 18 linear low-density polyethylene (LLDPE)/lowdensity polyethylene, 19,20 HDPE/polyamide 6 (PA6), 21 PS/EPDM, 22,23 PP/PA6, 24 poly(lactic acid)/poly(butylene adipate-co-terephthalate), 25 ethylene-a-olefin copolymers (POE)/PS, 26 PA6/POE/POE grafted with maleic anhydride (POE-g-MAH), 27 LLDPE/POE, 28 polyethylene terephthalate (PET)/LCP, 29 polyethylene naphthalate (PEN)/liquid crystalline polymers (LCP), 30 PET/PEN, 31 blends of two different LCPs. 32 Most articles reported the in situ copolymerization of polymers by the ultrasonic treatment, as patented by Isayev and Hong. 33 The Fourier transform infrared (FTIR) analysis of HDPE/PS, 7 PP/PS, 9 PP/EPDM, 14,16 and PS/EPDM 22 blends prepared by ultrasonic treatment showed the presence of chemical structure of the dissolved polymer phas...…”

Section: Introductionmentioning

confidence: 99%

Natural rubber/styrene butadiene rubber blends prepared by ultrasonically aided extrusion

Choi

Isayev

2013

Journal of Elastomers & Plastics

View full text Add to dashboard Cite

Ultrasonically aided extrusion of natural rubber (NR), styrene butadiene rubber (SBR), and NR/SBR blends with ratio of 70/30, 50/50, and 30/70 were carried out at various ultrasonic amplitudes up to 10 mm. A die pressure of NR and NR/SBR blends continuously decreased with increase of ultrasonic amplitude, while that of SBR showed a slight increase with increase in amplitude from 5.0 to 7.5 mm due to a dominant effect of SBR gel formation. Complex dynamic viscosity, minimum and maximum torque of curing curves of NR, SBR, and NR/SBR blends, and cross-link density and gel fraction of their vulcanizates were decreased by the ultrasonic treatment at an amplitude of 10 mm, due to the molecular chain scission. The latter also led to a decrease in the hardness, modulus at a strain of 100%, and abrasion resistance of NR and NR/SBR blends. However, the modulus and abrasion resistance of SBR showed an improvement at amplitude of 7.5 mm, due to a dominant effect of gel formation. Both the tensile strength and elongation at break of ultrasonically treated NR/SBR blends showed a maximum at amplitude of 5.0 mm, with the modulus at a strain of 100% not being affected. Morphological studies using the phasecontrast optical microscope and atomic force microscopy showed a reduction in the size of rubber phases and a better homogeneity of NR/SBR blend by the ultrasonic treatment at amplitude of 5.0 mm. Accordingly, the increase in both the tensile strength and elongation at break of ultrasonically treated NR/SBR blends at an amplitude of 5.0 mm is mainly ascribed to the lower size of rubber phases and improved uniformity of blend caused by the ultrasonic treatment.

show abstract

Liquid Crystalline Composite

Isayev

2012

Wiley Encyclopedia of Composites

View full text Add to dashboard Cite

A review of novel technologies for manufacturing composites involving liquid crystalline polymers (LCPs) is presented. In particular, this review provides a classification scheme of various types of LCPs, with a special emphasis paid to the history, key approaches, milestones in developments of thermotropic LCPs, and their commercialization. Methods of characterization of LCPs by optical and electron microscopy, X‐ray diffraction, NMR, light scattering, and thermal, rheological, and mechanical techniques are discussed. The development of the concept of self‐reinforced or in situ composites based on blending LCPs with flexible‐chain polymers and LCPs with other LCPs is presented. In these composites, the dispersed fibrous reinforcing LCP species in polymer matrices are not actually present before the processing of the resin, but come into existence during the processing step. Various aspects of manufacturing of these composites are discussed including methods of mixing and compounding, transition temperatures, different factors governing LCP fibrillations, effects of LCP on crystallization of thermoplastic matrices, rheology of composites, and the use of LCP as a processing aid for thermoplastics. Special attention is paid to manufacturing and mechanical properties of the composites based on LCP/thermoplastic, LCP/LCP and ternary blends, and LCP/thermoplastic and LCP/LCP laminates. The effect of compatibilization and anisotropy of composites are also considered along with proposed approaches to reduce their anisotropy. Finally, various existing and future possibilities for industrial applications of self‐reinforced composites are discussed.

show abstract

Ultrasonically-aided extrusion of blends of two thermotropic LCPs

Cited by 7 publications

References 20 publications

Numerical and experimental studies for gas assisted extrusion forming of molten polypropylene

Numerical and experimental studies for gas assisted extrusion forming of molten polypropylene

Natural rubber/styrene butadiene rubber blends prepared by ultrasonically aided extrusion

Liquid Crystalline Composite

Contact Info

Product

Resources

About