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- 저자 : Maria de Fátima Vieira Marques (검색결과 2 건)
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Jose Jonathan Rubio Arias,Juliana Lunz,Bruno De Paula Amantes,Maria De Fátima Vieira Marques 한국섬유공학회 2020 Fibers and polymers Vol.21 No.6
The surface of Curauá (Ananas Erectifolius) fibers was successfully modified, characterized and applied asreinforcement on polypropylene composites through two different techniques: in situ polymerization and melt mixture. Thebest results in terms of mechanical performance were obtained for composites prepared through melt mixture technique withfibers submitted to moderate hydrolysis conditions (H2SO4 10 %, 1 h, 40 ºC, Ultrasound 30 min) and further acetylation withthe incorporation of compatibilizing agent PPMA as well as for the fiber with further silanization without PPMA. Thosefibers caused more than 100 % of elastic module improvement with respect to pristine polymer. Glass transition temperaturealso was increased with the incorporation of A. Erectifolius fibers as well as degradation temperature. Scanning electronmicroscopy permitted to verify that most of the mechanical properties is lost because of high ratio of empty spaces (mainly inthe case of in situ composites).
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Fibers of Ultra-High Molecular Weight Polyethylene Obtained by Gel Spinning with Polyalphaolefin Oil
Naiara Pirahi da Silva Chagas,Geíza Lopes da Silva Fraga,Maria de Fátima Vieira Marques 한국고분자학회 2020 Macromolecular Research Vol.28 No.12
The rapid growth of polymer technology has provided viable and more straightforward methods for the development of ultra-high molecular weight polyethylene (UHMWPE) fibers. The gel spinning process yields fibers with improved properties and less impact on the environment. The material used as a solvent for the swelling of the polymer reveals an excellent potential for the processing of new fibers. In the present work, the influence of a new spinning solvent based on polyalphaolefin (PAO100) in the UHMWPE was evaluated. All fibers were obtained by extrusion in concentrations of 0.04 to 60% m/m of PAO100 oil, with screw rotation speed increasing from 20 to 60 rpm, leaving the extruder nozzle of 1.82 mm. Besides, n-hexane was used in the process of extracting oil from UHMWPE fibers. The fibers did not undergo to the drawing process. The results show that the fibers containing 20-40% m/m of PAO100 presented higher linear density, indicating the orientation of the crystals in a compact morphology and the higher relaxation after leaving the nozzle, increasing die-swell. After extraction of PAO100 with n-hexane, huge voids were observed in SEM images, which indicates the alignment of subfibers inside the fiber. The average size of the crystallite related to the polyethylene orthorhombic crystal increased significantly, showing that the number of entanglements decreased. The results indicate that PAO100 oil acts as a lubricant, increasing the mobility of the chains, leading to higher crystallization. The present study presents exciting findings on the effects of PAO100 oil on the morphology, crystalline structures, and thermal properties of UHMWPE fibers, pointing out the oil concentration necessary for the formation of fibers with higher crystallinity and thermal resistance.
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