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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Avaliação da ação de estabilizantes anti-UV no desempenho de compósitos de polipropileno, reforçados com fibras de coco, submetidos a diferentes técnicas de envelhecimento artificial / Evaluation of anti-uv stabilizers action in coir fiber reinforced polypropylene composites performance, submitted to different techniques artificial weathering

Staffa, Lucas Henrique 30 June 2016 (has links)
Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-10-13T13:52:59Z No. of bitstreams: 1 DissLHS.pdf: 5329246 bytes, checksum: bf67aefa7ab3954057f79b20b3f10988 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T13:47:37Z (GMT) No. of bitstreams: 1 DissLHS.pdf: 5329246 bytes, checksum: bf67aefa7ab3954057f79b20b3f10988 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T13:47:43Z (GMT) No. of bitstreams: 1 DissLHS.pdf: 5329246 bytes, checksum: bf67aefa7ab3954057f79b20b3f10988 (MD5) / Made available in DSpace on 2016-10-21T13:47:49Z (GMT). No. of bitstreams: 1 DissLHS.pdf: 5329246 bytes, checksum: bf67aefa7ab3954057f79b20b3f10988 (MD5) Previous issue date: 2016-06-30 / Não recebi financiamento / Currently, there has been a search for economically viable and sustainable products in various market segments. Lighter materials that can be recycled have become a strategic issue for many industries. In this sense, the utilization of lignocellulosic fibers in polymeric composites, are becoming increasingly viable as substitutes for inorganic minerals reinforcements, mainly glass fibers. In this study, polypropylene (PP) natural composites reinforced with coir fiber (CF), compatibilized with maleic anhydride grafted polypropylene (PPMAH) and stabilized with a hindered amine (Tinuvin® 791) and UV absorber (Hostavin® ARO 8), were prepared via extrusion. The effect of the additives and their interactions and the influence of 1000 hours exposure in two types of accelerated weathering (Ultraviolet B and xenon arc) in the PP/CF composites were analyzed by mechanical properties (tensile properties), scanning electron microscopy (SEM), differential Scanning Calorimetry (DSC) and colorimetry. The results indicate that the incorporation of coir fiber, in the presence of the compatibilizer, significantly increases tensile strength, but in the absence of the compatibilizer, the coir fiber act as stress concentrators, allowing a lower tensile strength to the sample.The joint presence of Tinuvin® and the compatibilizer has a negative effect on tensile strength and on the compatibility of the natural fiber with the matrix. UV absorber did not affect the compatibility of the PP/CF composites. Post-weathering results indicate that UVB caused more intense degradation than xenon arc. However, decreasing Tinuvin® efficiency evidence were not possible to be confirmed. Through electron micrographs, DSC analysys and tensile tests, it is noted the additive system based on (Tinuvin®+ Hostavin®) as the most effective protection system against the artificial weathering. / Atualmente, tem-se observado a busca por produtos viáveis economicamente e sustentáveis em vários segmentos do mercado. Materiais mais leves e que possam ser reciclados se tornaram uma questão estratégica para muitas indústrias. Neste contexto, a utilização de fibras lignocelulósicas em compósitos poliméricos, estão se tornando cada vez mais viáveis como substitutas de reforços minerais inorgânicos, como a fibra de vidro. Neste trabalho, compósitos naturais de polipropileno reforçados com fibra de coco (FCo), compatibilizados com polipropileno enxertado com anidrido maleico (PPMAH) e estabilizados com uma amina estericamente impedida (Tinuvin® 791) e um absorvedor de UV (Hostavin® ARO 8), foram preparados via extrusão. Os efeitos dos aditivos e de suas interações e a influência de 1000 horas de exposição em duas fontes de intemperismo acelerado (ultravioleta B e arco xenônio) dos compósitos de PP/FCo, foram analisados através das propriedades mecânicas, em tração, microscopia eletrônica de varredura (MEV), calorimetria exploratória diferencial (DSC) e colorimetria. Os resultados obtidos mostram que a incorporação da fibra de coco, na presença do agente compatibilizante, confere aumentos significativos de resistência à tração, mas que na ausência deste, as fibras de coco se comportam como concentradores de tensões conferindo menor resistência à tração. A presença conjunta de Tinuvin® e agente compatibilizante gera um efeito negativo na resistência à tração e na compatibilidade da fibra natural com a matriz. O absorvedor UV não afetou a compatibilidade dos compósitos PP/FCo. A análise dos resultados pós-intemperismo revelou que a fonte UVB gerou degradação mais intensa que a fonte de arco xenônio. Porém, evidências da diminuição da eficiência do Tinuvin® não foram possíveis de serem confirmadas. Através das micrografias eletrônicas, DSC e ensaios de tração, constata-se o sistema de aditivação composto por Tinuvin®+ Hostavin® como o mais eficaz frente ao intemperismo artificial.
2

INCORPORATION OF BIO BASED FLAX FIBER REINFORCED POLYMER SKINS FOR PACKAGING ENHANCEMENTS

Sufia Suleman Sukhyani (11679325) 20 December 2021 (has links)
This thesis provides an approach to incorporate natural composites like Flax Fiber using a resin with 30% bio-content to enhance the packaging boxes made of corrugated cardboard. The objective of introducing natural composite skins is to reduce/eliminate the compressive loading subjected to the boxes while stacking in warehouses.
3

Incorporation of Bio Based Flax Fiber Reinforced Polymer Skins for Packaging Enhancements

Sukhyani, Sufia 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis provides an approach to incorporate natural composites like Flax Fiber using a resin with 30% bio-content to enhance the packaging boxes made of corrugated cardboard. The objective of introducing natural composite skins is to reduce/eliminate the compressive loading subjected to the boxes while stacking in warehouses.

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