The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
J S Yang - One of the best experts on this subject based on the ideXlab platform.
-
an organically modified montmorillonite nylon 12 composite powder for selective laser sintering
Rapid Prototyping Journal, 2011Co-Authors: J S YangAbstract:Purpose – The purpose of this paper is to reinforce the selective laser sintering (SLS) parts of nylon‐12 using organically modified montmorillonite (OMMT).Design/methodology/approach – A dissolution‐precipitation process is developed to prepare an OMMT/nylon‐12 composite powder (3 wt% OMMT). X‐ray diffraction (XRD) was used to characterize nanostructure features. The dispersion of OMMT in the nylon‐12 matrix was observed by scanning electron microscope (SEM). The effect of OMMT on the thermal properties of nylon‐12 was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the SLS parts made from the composite powder and neat nylon‐12 powder were measured and compared.Findings – The X‐ray diffraction and SEM results indicate that the OMMT is intercalated by nylon‐12 molecular chains and uniformly dispersed in the nylon‐12 matrix during the dissolution‐precipitation process, and thus the OMMT/nylon‐12 intercalated nanocomposites are formed. Th...
-
An organically modified montmorillonite/nylon‐12 composite powder for selective laser sintering
Rapid Prototyping Journal, 2011Co-Authors: J S YangAbstract:Purpose – The purpose of this paper is to reinforce the selective laser sintering (SLS) parts of nylon‐12 using organically modified montmorillonite (OMMT).Design/methodology/approach – A dissolution‐precipitation process is developed to prepare an OMMT/nylon‐12 composite powder (3 wt% OMMT). X‐ray diffraction (XRD) was used to characterize nanostructure features. The dispersion of OMMT in the nylon‐12 matrix was observed by scanning electron microscope (SEM). The effect of OMMT on the thermal properties of nylon‐12 was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the SLS parts made from the composite powder and neat nylon‐12 powder were measured and compared.Findings – The X‐ray diffraction and SEM results indicate that the OMMT is intercalated by nylon‐12 molecular chains and uniformly dispersed in the nylon‐12 matrix during the dissolution‐precipitation process, and thus the OMMT/nylon‐12 intercalated nanocomposites are formed. Th...
R. A. Shanks - One of the best experts on this subject based on the ideXlab platform.
-
Effect of elastomer on polypropylene/Nylon-12 blends
Journal of Materials Science, 1996Co-Authors: Yu Long, R. A. ShanksAbstract:Various compositions of polypropylene (PP)/Nylon-12 blends with elastomer were prepared. Morphologies and mechanical properties of the blends were studied. In particular, the effect of ethylene-propylene (EP) elastomer and maleic anhydride-grafted ethylene propylene elastomer (Ma-g-EP) on the PP/Nylon-12 blends were investigated. The results showed that PP/Nylon-12 blends have inferior mechanical properties because of their poor compatibility and dispersion. The EP elastomer has a limited effect on the blends since the mechanical properties of PP/Nylon-12 blends were controlled by their interface. The Ma-g-EP elastomer improved the mechanical properties of PP/Nylon-12 blends through improvement of the interface between PP and Nylon-12, and compatibility between the elastomer and Nylon-12. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to characterize microstructures. The dispersion of components and the compatibility between PP and Nylon-12 were significantly improved with addition of the Ma-g-EP elastomer.
Young-wook Chang - One of the best experts on this subject based on the ideXlab platform.
-
Supramolecular thermoplastic elastomer with thermally scratch repairable effect from 3‐amino‐1,2,4‐triazole crosslinked maleated polyethylene‐octene elastomer/nylon 12 blends
Journal of Applied Polymer Science, 2014Co-Authors: Muhammad Kashif, Young-wook ChangAbstract:In this study, nylon 12 (5-25 wt %) was melt blended with a supramolecular thermally repairable thermoplastic elastomer (ATA-POE), which was generated by crosslinking of maleated polyethylene-octene elastomer (mPOE) with 3-amino-1,2,4-triazole (ATA), in an internal mixer. The effect of nylon 12 content on the phase morphology, thermomechanical properties, and thermally triggered scratch repairing effects of the ATA-POE/nylon 12 blends was investigated. Scanning electron microscopy results showed that nylon 12 formed a dispersed phase with submicron scale in a continuous ATA-POE phase. Fourier transform infrared spectros- copy and differential scanning calorimetry analysis revealed that there are extensive hydrogen bonding interactions between the ATA- POE and nylon 12 in the blends, which was manifested by a decrease in the melting temperature of each polymer component. Tensile and dynamic mechanical test showed that tensile modulus increased with increasing nylon 12 contents in the blend with maintaining fairly high elastic recoverability. Furthermore, the blends containing up to 20 wt % of nylon 12 showed good scratch repairing effects when they are heated above melting temperature of the ATA-POE phase in the blend. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41511.
-
Supramolecular thermoplastic elastomer with thermally scratch repairable effect from 3-amino-1,2,4-triazole crosslinked maleated polyethylene-octene elastomer/nylon 12 blends
Journal of Applied Polymer Science, 2014Co-Authors: Muhammad Kashif, Young-wook ChangAbstract:In this study, nylon 12 (5-25 wt %) was melt blended with a supramolecular thermally repairable thermoplastic elastomer (ATA-POE), which was generated by crosslinking of maleated polyethylene-octene elastomer (mPOE) with 3-amino-1,2,4-triazole (ATA), in an internal mixer. The effect of nylon 12 content on the phase morphology, thermomechanical properties, and thermally triggered scratch repairing effects of the ATA-POE/nylon 12 blends was investigated. Scanning electron microscopy results showed that nylon 12 formed a dispersed phase with submicron scale in a continuous ATA-POE phase. Fourier transform infrared spectros- copy and differential scanning calorimetry analysis revealed that there are extensive hydrogen bonding interactions between the ATA- POE and nylon 12 in the blends, which was manifested by a decrease in the melting temperature of each polymer component. Tensile and dynamic mechanical test showed that tensile modulus increased with increasing nylon 12 contents in the blend with maintaining fairly high elastic recoverability. Furthermore, the blends containing up to 20 wt % of nylon 12 showed good scratch repairing effects when they are heated above melting temperature of the ATA-POE phase in the blend. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41511.
-
Shape memory thermoplastic elastomer from maleated polyolefin elastomer and nylon 12 blends
Polymer Bulletin, 2014Co-Authors: Myung Chan Choi, Ji-yeon Jung, Young-wook ChangAbstract:Semicrystalline maleated polyolefin elastomer (mPOE) and nylon 12 were melt blended in an internal mixer at 200 °C with proportions of 90/10, 80/20, and 70/30 wt/wt, respectively. Molau test, melt viscosity measurement, differential scanning calorimetry, dynamic mechanical analysis and tensile testing were con-ducted to characterize the structure and properties of the blends. The results revealed that POE-graft-nylon 12 copolymer was formed during the mixing, and the blends show two melting transitions at 57–60 and 174–178 °C attributed to mPOE and nylon 12, respectively, which are dependent on the blend composition. The blends exhibit typical thermoplastic elastomeric behavior and their tensile modulus, strength and hardness increase with increasing nylon content. It was also observed that the blends form a physically crosslinked structure until the melting transition of nylon 12. The blends exhibit excellent thermally triggered shape memory effect, i.e., almost 100 % shape fixity rate and 100 % shape recovery rate, and the recovery occurs in a few seconds when the temporarily fixed shaped sample is heated just above the T m of mPOE phase in the blends.
Lon J Mathias - One of the best experts on this subject based on the ideXlab platform.
-
solution 13c nmr spectroscopy of polyamide homopolymers nylons 6 11 12 66 69 610 and 612 and several commercial copolymers
Polymer, 2001Co-Authors: Rick D Davis, William L Jarrett, Lon J MathiasAbstract:Abstract Well-resolved 13 C NMR spectra of nylons 6, 11, 12, 66, 69, 610, and 612 dissolved in 4:1 TFE/CDCl 3 allowed complete assignment of all major backbone peaks. In addition, several low intensity peaks were identified representing cis amide groups, acid end-groups and amine end-groups. Several peaks associated with the trans amide units in the spectra of each polyamide homopolymer were identified as uniquely characteristic of that polymer. Using these unique peaks, all the polyamides studied could be distinguished from each other as homopolymers and as repeat units in copolymers. For example, three unknown polyamides (supplied by a colleague) were identified as nylon 6, nylon 66 and nylon 610 using only solution 13 C NMR spectroscopy. Based on these results, several commercial polymers were examined. Using solution 13 C NMR spectroscopy, the copolymer compositions, molecular weights, end-group and cis amide contents, plus the amount of residual e-caprolactam were all determined. For example, Spiderwire Super Mono ® fishing line was found to have a number average molecular weight of 25,333 g/mol and to contain 82 mol% nylon 6 repeat units and 18 mol% nylon 66 repeat units. The residual e-caprolactam, acid end-group and amine end-group contents were calculated as 1.25, 0.61 and 0.0 mol%, respectively. The cis amide contents were calculated to be 1.2 mol% for nylon 6 units and 0.61 mol% for nylon 66 segments.
-
Solid-state NMR characterization of copolymers of nylon 11 and nylon 12
Solid state nuclear magnetic resonance, 1997Co-Authors: C. G. Johnson, Lon J MathiasAbstract:Solid-state 13C and 15N NMR spectroscopy, in conjunction with differential scanning calorimetry, wide-angle X-ray diffraction and infrared spectroscopy, were used to characterize a series of nylon 11 and 12 copolymers with mole percentages of nylon 12 monomer of 0, 15, 35, 50, 65, 85, and 100%. Monotonic melting point (Tm) and heat of fusion depressions were observed for the copolymer series with the 65 mol% nylon 12 copolymer having the lowest apparent crystallinity and Tm at 148 degrees C. Solid-state 15N NMR spectra showed a smooth shift of the main peak position for the as-prepared copolymers from 84 ppm for the alpha-form of pure nylon 11 to 89 ppm for the gamma-form of pure nylon 12. Similar behavior was seen for FTIR amide V and VI modes which are also sensitive to the alpha- and gamma-crystal forms. 13C NMR T1 measurements showed that the overall most mobile sample was the 65:35 copolymer. The amide group of the 1:1 copolymer was labelled using 15N-labelled amino acids available through the Gabriel synthesis; an annealed, solution-cast film of this sample showed a T1N value of 349 s, similar to values seen for annealed nylon 11 and nylon 12 homopolymers. The WAXS pattern for the 65 mol% nylon 12 sample showed a sharp peak at 2 theta = 21.3, overlapping a broad peak centered at 2 theta = 21.0. These are consistent with the values seen for gamma-form nylon 12. The 1:1 copolymer (15N labelled) was shown to be polymorphic, like the homopolymers after specific treatments, with a gamma-like phase formed upon solvent casting, and an alpha-like phase dominating for as-polymerized material and precipitated flakes.
-
Synthesis and Characterization of Copolymers of Nylon 11 and Nylon 12
1993Co-Authors: C. G. Johnson, Lon J MathiasAbstract:Abstract : A series of copolymers was prepared from 11-aminoundecanoic and 12- aminododecanoic acids by melt-condensation at 210 degree C in sealed tubes under vacuum. Mole percentages of nylon 12 monomer were 0, 15, 35, 50, 65, 85, and 100 percent in the feed. The amide group was labelled using nitrogen 15-labelled amino acids available through the Gabriel synthesis (only the 1:1 copolymer was enriched with nitrogen-15). Solid-state carbon 13 (at 100.6 MHz) and nitrogen 15 (at 20.3 MHz) NMR spectroscopy, differential scanning calorimetry, wide-angle x- ray diffraction, and infrared spectroscopy were used to characterize the copolymers. Solid-state nitrogen 15 NMR spectra showed a smooth shift of the main peak position from 84 ppm for alpha-nylon 11 to 89 ppm for gamma-nylon 12 for the as-prepared copolymers. Similar behavior was seen from amide V and VI modes which are sensitive the alpha- and gamma-crystal forms. Carbon-13 NMR T1 measurements showed that the most mobile sample was the 63:35 nylon 11-co-12 polymer
-
Solid-State NMR Investigation of Nylon 12
Macromolecules, 1991Co-Authors: Lon J Mathias, C. Greg JohnsonAbstract:Nylon 12 with > 99% 15 N labeling of the amide nitrogen was synthesized and used to prepare samples rich in the γ-form, γ'-form and α-form. Solid state 13 C and 15 N NMR were used to characterize the polymer samples.
Yu Long - One of the best experts on this subject based on the ideXlab platform.
-
Effect of elastomer on polypropylene/Nylon-12 blends
Journal of Materials Science, 1996Co-Authors: Yu Long, R. A. ShanksAbstract:Various compositions of polypropylene (PP)/Nylon-12 blends with elastomer were prepared. Morphologies and mechanical properties of the blends were studied. In particular, the effect of ethylene-propylene (EP) elastomer and maleic anhydride-grafted ethylene propylene elastomer (Ma-g-EP) on the PP/Nylon-12 blends were investigated. The results showed that PP/Nylon-12 blends have inferior mechanical properties because of their poor compatibility and dispersion. The EP elastomer has a limited effect on the blends since the mechanical properties of PP/Nylon-12 blends were controlled by their interface. The Ma-g-EP elastomer improved the mechanical properties of PP/Nylon-12 blends through improvement of the interface between PP and Nylon-12, and compatibility between the elastomer and Nylon-12. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to characterize microstructures. The dispersion of components and the compatibility between PP and Nylon-12 were significantly improved with addition of the Ma-g-EP elastomer.