Navegando por Data de Publicação, começando com "2009-09-25"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 3 de 3

Influência da compatibilização interfacial seletiva nas propriedades mecânicas de compósitos híbridos ternários de PET/fibra de vidro/elastômeros olefínicos reativos
(Universidade Federal de São Carlos, 2009-09-25) Carvalho, Gustavo Baldi de; Sousa, José Alexandrino de; https://lattes.cnpq.br/7737833809468759; https://lattes.cnpq.br/2108032825479988
Poly(ethylene terephthalate) (PET) is a semi-crystalline thermoplastic widely used for packaging of aereted soft drinks, which makes the recycling of post-consumer PET material necessary to prevent the negative environmental impact of its disposal. The recycling of PET as an engineering thermoplastic can be accomplished by the incorporation of glass fiber (GF) and elastomeric impact modifier to the PET matrix, forming a ternary hybrid composite. To assure an appropriate balance of mechanical properties of stiffness, strength and toughness in this composite, it is important that the GF and rubber particles are dispersed separately in the matrix, avoiding the encapsulation of the fibers by the rubber phase and promoting, simultaneously GF reinforcement and rubber toughening mechanisms. In this work, the influence of selective interfacial compatibilization on the mechanical properties of hybrid composites of recycled PET was studied, as the matrix polymer was modified with reactive olefin elastomers of E-MA-GMA and E-EA-MAH, as well as with short GF treated with either epoxy (FV952) or aminesilanes (FV983). Ternary systems of PET/E-MA-GMA/FV952, PET/E-MA-GMA/FV983 and PET/E-EA-MAH/FV983 were compounded in a twin-screw corotating ZSK-30 extruder and, depending on the relative reactivities of PET s chain-end groups with the functionalities present on the GF surfaces and in the E-MA-GMA and E-EA-MAH terpolymers, the GF is encapsulated or not by the elastomer phase and, consequently, the mechanical properties of the hybrid composites are affected differently. Mechanical tests and torque rheometry data indicated high reactivity between PET and E-MA-GMA terpolymer, and low reactivity with the E-EA-MAH. Analysis of tensile and Izod impact tests results, as well as from fiber-polymer interfaces observations by SEM, indicated good fiber-polymer adhesion in PET/E-MA-GMA/FV952 and PET/E-MA-GMA/FV983 systems, and fiber encapsulation by rubber particles in the case of the PET/E-EA-MAH/FV983 system.
Mobilidade ascendente, identidade e estilos de vida do negro (a) no interior paulista: o caso de São Carlos e Araraquara
(Universidade Federal de São Carlos, 2009-09-25) Martins, Thais Joi; Silvério, Valter Roberto; https://lattes.cnpq.br/9421231847055027; https://lattes.cnpq.br/1495908295162360
This work has the focus to bring reflection about identity and trajectory of some black professionals and businessman from west of the State of Sao Paulo. We search to know how these black people walk their path and lifestyle and meaning and remaining their identity when reach important posts and positions at the work market, that is, when reach a raising social and economic mobility. In this way, first counting on a bibliographic review about the thematics cited above and subsequently with an analytic descriptive moment that will count on exposition and analysis of the data obtained in interviews made with middle class black people from local authority of Sao Carlos and Araraquara. It has also the intention to do a qualitative analysis so we can get more precisely results for reflection in a conclusive way about the construction of the black people s identity and insertion in the Brazilian work market.
Metaheurística tabu aplicada ao problema de carregamento de contêiner com caixas idênticas
(Universidade Federal de São Carlos, 2009-09-25) Poli, Guilherme Izidoro; Pureza, Vitória Maria Miranda; https://lattes.cnpq.br/2842453464277778
Intermodal transport, that is, the integration between different transport modes was facilitated by the use of containers. The stowage devices in the breakdown of the cargo is an important logistics activity, since the total volume actually used can affect significantly the cost of transporting the products. This approach addresses the Container Loading Problem, which more generally consists in arranging items (for example, products packaged in boxes) of various sizes within larger objects (for example, containers) with the maximum use of the available volume. In particular, it is considered the special case where the boxes to be arranged are rectangular and identical (single sized) and there is only a single container. In order to tackle these problems, the 2006´s Tabu Search heuristic by Pureza and Morabito, originally proposed for the Manufacturer s Pallet Loading Problem, was extended. From an initial solution generated by a block heuristic, moves are applied to selected blocks in order to change their box orientation and/or to expand them in one of the six directions, which result in the reduction, elimination and creation of other blocks. Criteria for stability of the load are also addressed in this work. Computational experiments using a set of instances in the literature demonstrate the performance of the proposed approach.