The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Han Mo Jeong - One of the best experts on this subject based on the ideXlab platform.
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Morphological, thermal and rheological properties of the blends polypropylene/Nylon-6, polypropylene/Nylon-6/(maleic anhydride-g-polypropylene) and (maleic anhydride-g-polypropylene)/Nylon-6
European Polymer Journal, 2003Co-Authors: Sang Jin Park, Han Mo JeongAbstract:Abstract Melt blends of polypropylene(PP)/Nylon-6, PP/Nylon-6/(maleic anhydride-g-polypropylene-(MAH-g-PP)) and (MAH-g-PP)/Nylon-6 have been prepared using a Brabender plasticoder. Measured properties included steady shear viscosities from a capillary rheometer, thermal properties from DSC, and morphologies from SEM. The viscosity-composition curve, measured at low rate of shear, indicated negative deviation from the simple additive rule for PP/Nylon-6 blends, positive deviation for PP/Nylon-6/MAH-g-PP blends and positive and negative deviations for MAH-g-PP/Nylon-6 blends. The results have been interpreted in terms of morphological texture of the blends and chemical reactions between the constituent polymers.
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Nylon 6-polyethersulfone-Nylon 6 block copolymer: synthesis and application as compatibilizer for polyethersulfone/Nylon 6 blend
Polymer, 1998Co-Authors: Sung Chul Hong, Han Mo JeongAbstract:Abstract Nylon 6-polyethersulfone (PES)-Nylon 6 block copolymers were synthesized by anionic polymerization of ϵ-caprolactam using chlorine-terminated PES, a polymeric activator. The structure and properties of these block polymers were examined using infra-red, nuclear magnetic resonance, differential scanning calorimetry, transmission electron microscopy, and thermogravimetric analysis. The compatibilizing effects of this block copolymer on PES/Nylon 6 blends were investigated by examining thermal properties, morphology and dynamic mechanical characteristics. When the block copolymer was added, the size of dispersed phase in the blend decreased dramatically, and the glass transition temperatures of the constituent polymers converge. The improvement of dynamic tensile modulus and thermal resistance due to the dispersed PES phase were enhanced by the added block copolymer.
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Compatibilizing effect of polyarylate-Nylon 6 block copolymers on polyarylate/Nylon 6 blends: 1. Synthesis of polyarylate-Nylon 6 block copolymer and its miscibility in binary blends with polyarylate or Nylon 6
Polymer, 1993Co-Authors: Han Mo JeongAbstract:Abstract Polyarylate (PAR)-Nylon 6 block copolymers of various block lengths were prepared by the anionic polymerization of e-caprolactam using the polymeric activator from hydroxy-difunctional PAR and toluene diisocyanate. Phase-separated morphology of PAR-Nylon 6 block copolymer was observed by transmission electron microscopy and the thermal properties were measured by differential scanning calorimetry (d.s.c.). Partial miscibility between PAR and Nylon 6 segments was more evident with shorter constituent blocks. In binary blends of PAR or Nylon 6 with PAR-Nylon 6 block copolymer, molecular-level mixing of homopolymers with corresponding blocks of block copolymer was supposed from the thermal properties measured by d.s.c.
Donald R Paul - One of the best experts on this subject based on the ideXlab platform.
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rubber toughening of Nylon 6 nanocomposites
Polymer, 2006Co-Authors: Donald R PaulAbstract:The rubber toughening of Nylon 6 nanocomposites prepared from an organoclay was examined as a means of balancing stiffness/strength versus toughness/ductility. Nine different formulations varying in montmorillonite, or MMT, and maleated ethylene/propylene rubber or EPR-g-MA rubber content were made by mixing of Nylon 6 and organoclay in a twin screw extruder and then blending the nanocomposites with the rubber in a single screw extruder. In this sequence, the MMT platelets were efficiently dispersed in the Nylon 6 matrix. The MMT platelets did not penetrate into the rubber phase. The addition of clay affected the dispersion of the rubber phase resulting in larger and more elongated rubber particles. The tensile properties and impact strength of these toughened nanocomposites are discussed in terms of the MMT and rubber contents and morphology. There is a clear trade-off between stiffness/strength versus toughness/ductility.
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Nylon 6 nanocomposites prepared by a melt mixing masterbatch process
Polymer, 2004Co-Authors: Rhutesh K Shah, Donald R PaulAbstract:Abstract A melt mixing masterbatch process for preparing Nylon 6 nanocomposites that provides good exfoliation and low melt viscosities has been investigated. It is known that high molecular weight (HMW) grades of Nylon 6 lead to higher levels of exfoliation of organoclays than do low molecular weight (LMW) grades of Nylon 6. However, LMW grades of Nylon 6 have lower melt viscosities, which are favorable for certain commercial applications like injection molding. To resolve this, a two-step process to prepare nanocomposites based on Nylon 6 is explored here. In the first step, a masterbatch of organoclay in HMW Nylon 6 is prepared by melt processing to give exfoliation. In the second step, the masterbatch is diluted with LMW Nylon 6 to the desired montmorillonite (MMT) content to reduce melt viscosity. Wide angle X-ray scattering, transmission electron microscopy, and stress–strain analysis were used to evaluate the effect of the clay content in the masterbatch on the morphology and physical properties of the final nanocomposite. The melt viscosity was characterized by Brabender Torque Rheometry. The physical properties of the nanocomposites prepared by the masterbatch approach lie between those of the corresponding composites prepared directly from HMW Nylon 6 and LMW Nylon 6. A clear trade-off was observed between the modulus and melt processability. Masterbatches that have lower MMT content offer a significant decrease in melt viscosity and a small reduction in modulus compared to nanocomposites prepared directly from HMW Nylon 6. Higher MMT concentrations in the masterbatch lead to a less favorable trade-off.
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thermal expansion behavior of Nylon 6 nanocomposites
Polymer, 2002Co-Authors: P J Yoon, T D Fornes, Donald R PaulAbstract:The linear thermal expansion behavior of nanocomposites was measured and compared with the theory by Chow. Nanocomposites were prepared by melt mixing organically modified montmorillonite with high and low molecular weight (LMW) grades of Nylon 6 using a twin screw extruder. Thermal expansion measurements were made on samples taken from injection-molded Izod bars in the flow direction (FD), transverse direction (TD), and normal direction (ND). Addition of clay reduces the thermal expansion coefficient in both FD and TD while an increase is seen in ND; FD has a lower thermal expansion coefficient than TD. The latter suggests non-uniform orientation of exfoliated platelets about FD, since perfect alignment of disk-like platelets in an isotropic matrix must yield identical expansion coefficients for both FD and TD. High molecular weight (HMW) Nylon 6 nanocomposites resulted in lower thermal expansion than LMW Nylon 6 nanocomposites at the same organoclay content. This difference was attributed to the higher aspect ratio of particles (better exfoliation) in HMW Nylon 6 nanocomposites. Thermal expansion coefficients predicted from a theoretical composite model were compared to the experimental data. Platelet aspect ratios deduced in this way were found to be dependent on the specimen direction, which further suggests imperfect orientation of particles about FD. Morphological analysis by transmission electron microscopy support the conclusions drawn above.
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Nylon 6 nanocomposites by melt compounding
Polymer, 2001Co-Authors: Donald R PaulAbstract:Abstract Nylon 6–organoclay nanocomposites were prepared via direct melt compounding using a conventional twin screw extruder. The mechanical properties and morphology of these nanocomposites were determined and compared to similar materials made by an in situ polymerization process. The organoclay was well exfoliated into the Nylon 6 matrix when compounded with the twin screw extruder but use of a single screw extruder was far less effective. The mechanical properties of the organoclay nanocomposites were significantly increased with marginal decrease of ductility and showed much greater values than glass fiber composites.
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Impact-modified Nylon 6/polypropylene blends: 3. Deformation mechanisms
Polymer, 1995Co-Authors: A. González-montiel, Henno Keskkula, Donald R PaulAbstract:The processes that occur during the deformation of Nylon 6/polypropylene blends modified with maleated rubbers were identified by dilatometric measurements and electron microscopy. These toughening mechanisms were found to depend on the type of rubber used as modifier (ethylene-propylene random copolymer, EPR-g-maleic anhydride (MA), or styrene-ethylene/butylene-styrene triblock copolymer, SEBS-g-MA), and on the relative ratio of Nylon 6 to polypropylene (PP) in the blend. Blends based on EPR-g-MA showed significant volume dilation during deformation in a low strain rate tensile test. Electron microscopy techniques revealed that the main dilational mechanism in these blends is cavitation of the rubber dispersed as particles in the Nylon 6 phase and at the Nylon 6/PP interface. Similar results were obtained for specimens deformed in a high speed impact test. Except for one composition, Nylon 6/PP blends modified with SEBS-g-MA showed negligible changes in volume during slow tensile deformation, and no indication of dilational processes (as determined by electron microscopy) was found in broken specimens deformed under notched Izod impact conditions. However, cavitation of the rubber particles was observed in 80/20 Nylon 6/SEBS-g-MA blends deformed in the high speed impact test. This indicates that under appropriate stress and strain conditions, cavitation of SEBS-g-MA particles can occur. The structure and properties of the rubber and its particle size are factors that contribute to the differences in the extent of cavitation of Nylon 6/PP blends modified with SEBS-g-MA or EPR-g-MA.
D R Paul - One of the best experts on this subject based on the ideXlab platform.
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Morphology and mechanical properties of compatibilized Nylon 6/polyethylene blends
Polymer, 1999Co-Authors: R. A. Kudva, Henno Keskkula, D R PaulAbstract:Blends of Nylon 6 and polyethylene were investigated over a range of compositions. The polyethylenes used were grafted with maleic anhydride and, thus, have the potential to react with the amine end groups of Nylon 6 during melt processing. This study focuses on the effects of the concentration, viscosity and functionality of the maleated polyethylenes (PE-g-MA) on the rheological, morphological, and mechanical properties of Nylon 6/PE-g-MA blends. The impact properties of these blends are strongly influenced by the amount and type of maleated polyethylene used. A low viscosity maleated polyethylene was shown to be ineffective in toughening Nylon 6; this was because of the propensity of polyethylene to become continuous even when Nylon 6 was the majority component. Two higher viscosity maleated polyethylenes were able to produce blends with high impact strength and excellent low temperature toughness over a range of compositions. It was demonstrated that polyethylene materials containing a very low degree of anhydride functionality can generate blends with excellent impact properties. A brief portion of this study focused on ternary blends of Nylon 6, maleated polyethylene and nonmaleated polyethylene; in general, the impact properties of these blends improved as the Nylon 6 molecular weight increased and as the ratio of maleated polyethylene to nonmaleated polyethylene increased.
R. A. Kudva - One of the best experts on this subject based on the ideXlab platform.
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Morphology and mechanical properties of compatibilized Nylon 6/polyethylene blends
Polymer, 1999Co-Authors: R. A. Kudva, Henno Keskkula, D R PaulAbstract:Blends of Nylon 6 and polyethylene were investigated over a range of compositions. The polyethylenes used were grafted with maleic anhydride and, thus, have the potential to react with the amine end groups of Nylon 6 during melt processing. This study focuses on the effects of the concentration, viscosity and functionality of the maleated polyethylenes (PE-g-MA) on the rheological, morphological, and mechanical properties of Nylon 6/PE-g-MA blends. The impact properties of these blends are strongly influenced by the amount and type of maleated polyethylene used. A low viscosity maleated polyethylene was shown to be ineffective in toughening Nylon 6; this was because of the propensity of polyethylene to become continuous even when Nylon 6 was the majority component. Two higher viscosity maleated polyethylenes were able to produce blends with high impact strength and excellent low temperature toughness over a range of compositions. It was demonstrated that polyethylene materials containing a very low degree of anhydride functionality can generate blends with excellent impact properties. A brief portion of this study focused on ternary blends of Nylon 6, maleated polyethylene and nonmaleated polyethylene; in general, the impact properties of these blends improved as the Nylon 6 molecular weight increased and as the ratio of maleated polyethylene to nonmaleated polyethylene increased.
Benjamin S. Hsiao - One of the best experts on this subject based on the ideXlab platform.
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Solvent induced phase separation in a Nylon 6-b-polyimide-b-Nylon 6 triblock copolymer
Journal of Polymer Research, 1997Co-Authors: Qiang Fu, Bryan P. Livengood, Ching-chang Shen, Weihan Li, Frank W. Harris, Stephen Z. D. Cheng, Benjamin S. HsiaoAbstract:A series of new Nylon 6-b-polyimide-b-Nylon 6 (triblock) copolymers have been synthesized via condensation polymerization of the polyimide component and anionic polymerization of the Nylon 6 component. The polyimide component is prepared from bisphenol-A dianhydride (BisA-DA) and bisaniline-P diamine (BisP) with end-capped functional groups. After the polyimides are dissolved in caprolactam, the Nylon 6 anionic polymerization is initiated by the functional groups of the polyimides. The triblock copolymers can be dissolved in both m -cresol and 1,6-hexanediol. Of the two components present in the copolymers, Nylon 6 crystallizes partially and BisA-DA/BisP is amorphous. Based on differential scanning calorimetry, dynamic mechanical analysis, wide angle X-ray diffraction, small angle X-ray scattering and transmission electron microscopy experiments, the copolymer films prepared from the 1,6-hexanediol solution are phase separated. The BisA-DA/Bis P and the Nylon 6 components show little miscibility in the inter-lamellar amorphous region. However, in the films prepared from the m -cresol solution both components are largely miscible in the inter-lamellar amorphous region. This is due to the different solvation power of the two solvents with respect to the polyimide and Nylon 6.
