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195 results on '"Vancso, G.J."'

3. Interactions between sorbitol-type nucleator and additives for polypropylene

Author

Nguon, O.J., Charlton, Z., Kumar, M., Lefas, J., and Vancso, G.J.

Subjects
Crystallization -- Analysis, Nucleation -- Analysis, Polypropylene -- Usage, Sorbitol -- Usage, Engineering and manufacturing industries, Science and technology
Abstract

The thermal properties of a sorbitol-type nucleating agent (viz. 1,2,3-trideoxy4,6:5,7-bis-0-[(4-propylphenyl)methylene]-nonitol (TBPMN)) were examined in this study, and the influence of common processing additives assessed. In addition, we describe a novel approach to monitor in situ the self-assembly of the nucleator in presence of additives by optical microscopy. The performance of sorbitol compounds is closely associated to their chemical structure and ability to self-assemble. TBPMN formed elongated fibrils from the melt under inert atmosphere, in molted polypropylene, or in presence of antioxidants. However, calcium stearate (CaSt) and glycerol monostearate hampered growth, and yielded thinner fibrils. In presence of the additives, melting point depression of the nucleator occurred, and resulted in a lower degree of crystallinity upon cooling. Performance evaluation of the nucleator in polypropylene blends revealed an increased crystallization temperature when antioxidants were present, while CaSt inhibited nucleator activity. The effect of monoglycerides was found highly dependent on the processing conditions. Noteworthy, blends containing all the additives displayed the highest performance. This study highlights the importance of the preparation method of polymer additive blends to achieving the best performance in the final product. Characterization was performed by thermogravimetric analysis, Fourier-transform infrared spectroscopy, optical microscopy, and differential scanning calorimetry. KEYWORDS additives, clarifier, crystallization, nucleator, polypropylene, self-assembly, sorbitol, 1 | INTRODUCTION The versatile and attractive properties of polypropylene (PP) have established this polyolefin as one of the leading thermoplastic materials, with a global production reaching 56 million metric [...]

Published
2020
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9. Editor's note on 'Molecular-level insight of gas transport in composite poly(4-methyl-2-pentyne) and nanoparticles of titanium dioxide': (European Polymer Journal (2018) 102 (82–89), (S0014305717321973), (10.1016/j.eurpolymj.2018.03.022))

Author

Vancso, G.J. and Materials Science and Technology of Polymers

Abstract

Dr. Gary S. Grest contacted the journal with concerns about the publication of this paper and following investigation we are publishing this note to correct the scientific record. We have received written confirmation from the institute that no one of the name Gary Y. Grest was employed previously or currently, in either a temporary or permanent role at any of the Sandia Sites. In addition, to avoid any potential confusion we would like to clearly state that the named co-author Gary Y. Grest is not and should not be mistaken with Gary S. Grest. Dr. Gary S. Grest is a prestigious scientist with a genuine affiliation to Sandia National Laboratories and he is in no way related to or involved with any of the work described in this paper. Original text (mistake underlined): Gary Y. Grestb bSandia National Laboratories, Livermore, CA 94551-0969, United States Corrected text (underlined): Gary Y. Grestb bNo known affiliation Original text (mistake underlined): Acknowledgments. We acknowledge financial support from the National Science Foundation under Grants DMR-1309892, DMR-1436201, and DMR-1121107, the National Institutes of Health under Grants P01-HL108808 and 1UH2HL123645. Corrected text (underlined): The entire acknowledgments section should be removed from the paper. The reason for removing the listed funding sources is that these grants are all either past or current grants awarded to Dr Michael Rubinstein from Duke University who was in no way related or involved with any of the work described in this paper. Neither Quan Yang nor Gary Y. Grest were named or involved in the projects funded by these grants.

Published
2020

12. Studies of optical haze and surface morphology of blown polyethylene films using atomic force microscopy

Author

Smith, P.F., Chun, I., Liu, G., Dimitrievich, D., Rasburn, J., and Vancso, G.J.

Subjects
Polyethylene -- Research, Surface roughness -- Research, Engineering and manufacturing industries, Science and technology, Research
Abstract

Atomic force microscopy (AFM) has been used to examine the inner and outer surfaces of commercial blown polyethylene films. When this technique has been used, direct-space images of surface lamellae have been obtained, and the surface roughness determined. The haziness of the films has been measured, both in the as-produced state and when coated with suitable oil. Thus, both surface and bulk contributions to the apparent turbidity have been estimated. The aim of this study has been to correlate in turn the haziness, roughness, and surface morphology. Results obtained showed that the haze is related primarily to the surface roughness and can be reduced by lowering the frost line. AFM images unveiled lamellar features that were oriented predominantly in the transverse direction. The observed wide-angle X-ray diffraction (WAXD) intensities were consistent with an a-axis type of orientation., INTRODUCTION Polyethylene films produced by blown film extrusion account for the use of approximately 70% of the supply of linear low-density polyethylene (LLDPE) (1). For the majority of end uses [...]

Published
1996

16. Magnetic properties of large-area particle arrays fabricated using block copolymer lithography

Author

Cheng, Joy Y., Ross, C.A., Thomas, E.L., Smith, Henry I., Lammertink, R.G.H., and Vancso, G.J.

Subjects
Magnetism -- Research, Block copolymers -- Usage, Cobalt, Particles -- Research, Lithography -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

50-nm period arrays of Co particles with widths of 35 nm and heights of 5-20 nm have been made using a self-assembled block copolymer lithography. The magnetic particles have in-plane anisotropy due to their shape, and show thermally activated reversal with an activation volume larger than their physical volume, which is attributed to magnetic interactions between the particles. Index Terms--Activation volume, block copolymer lithography, cobalt nanoparticles, self-assembly.

Published
2002

19. Magnetic reversal phenomena of perpendicular magnetic islands fabricated by block copolymer lithography

Author

Ilievski, Filip, Ross, C.A., and Vancso, G.J.

Subjects
Cobalt alloys -- Magnetic properties, Magnetization -- Analysis, Platinum -- Magnetic properties, Physics
Abstract

The magnetic properties of perpendicular CoCrPt magnetic uniaxial islands, which are fabricated by templated block copolymer lithography, are studied. Magnetic analysis has indicated that the ligands have reversed their magnetization in a coherent and independent fashion.

Published
2008

31. Surface nano-and microstructuring with organometallic polymers

Author

Korczagin, I., Lammertink, Rob G.H., Hempenius, Mark A., Golze, S., Vancso, Gyula J., Vancso, G.J., Reiter, G., and Materials Science and Technology of Polymers

Subjects
Nanolithography, Materials science, Microcontact printing, Polymer chemistry, Nanotechnology, Substrate (electronics), Dewetting, Reactive-ion etching, Thin film, METIS-249851, Lithography, Soft lithography
Abstract

This paper gives an overview of the use of poly(ferrocenylsilane)s in the surface patterningof silicon substrates. Due to the presence of iron and silicon in their main chain, poly(ferrocenylsilane)sshow a very high resistance to reactive ion etching, allowing one to transfer polymer patternsdirectly onto the substrate. Methods for introducing etch-resistant polymer patterns on substratesurfaces include soft lithography approaches such as microcontact printing, directed dewetting, andcapillary force lithography. Next to top-down methods, self-assembly strategies are discussed. Phaseseparation in thin films of asymmetric organic–organometallic block copolymers leads to theformation of nanoperiodic organometallic patterns. The use of such thin films as nanolithographictemplates is demonstrated. Surface patterning can also be realized using electrostatic self-assemblyof organometallic polyions. Layer-by-layer deposition of poly(ferrocenylsilane) polyanions and polycationson chemically patterned substrates allows one to guide the growth of multilayer thin films and toproduce patterned organometallic coatings.

Published
2006
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37. Controlled Carbon Nanotube Growth on Block Copolymer Templates

Author

Hinderling, C., Keles, Y., Stöckli, T., Knapp, H.F., De los Arcos, T., Oelhaven, P., Korczagin, I., Hempenius, M.A., Vancso, G.J., Pugin, R., Heinzelmann, H., and Materials Science and Technology of Polymers

Subjects
METIS-221828
Published
2004

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