RESUMO A intensa atividade industrial na região Amazônica gera grande quantidade de resíduos, entre eles, os resíduos lignocelulósicos não madeireiros. O presente estudo avaliou a utilização do tegumento de murumuru (Astrocaryum murumuru Mart.) na produção de um compósito de madeira plástica, em que se utilizou a proporção 70/30 de polipropileno e tegumento de murumuru e 2% de anidrido maleico. Os compósitos de madeira plástica foram moldados por compressão em uma prensa termo hidráulica. O tegumento de murumuru foi caracterizado quanto ao seu teor de lignina e celulose e quanto a sua morfologia através de Microscopia Eletrônica de Varredura (MEV). Os compósitos foram avaliados quanto a sua morfologia por meio do MEV e quanto as suas propriedades mecânicas por meio do ensaio de resistência a flexão, onde as placas de PP puro apresentaram desempenho mecânico 21,7% superior ao compósito com 30% de resíduo, para valores de significância (P < 0,05) não houve diferença estática entre as placas. Os padrões de espectrometria de infravermelho indicaram que a composição da carga vegetal se caracteriza de constituintes como lignina, celulose e hemicelulose. Os resultados obtidos indicaram bom desempenho da madeira plástica, desta forma, o objetivo deste trabalho foi alcançado.

ABSTRACT The intense industrial activity in the Amazon region generates a large amount of waste, including non-wood lignocellulosic waste. The present study evaluated the use of murumuru tegument (Astrocaryum murumuru Mart.) in the production of a plastic wood composite, in which a 70/30 proportion of polypropylene and murumuru tegument and 2% maleic anhydride were used. The wood-plastic composites were compression molded in a thermo-hydraulic press. The murumuru tegument was characterized as to its lignin and cellulose content and as to its morphology through Scanning Electron Microscopy (SEM). The composites were evaluated for their morphology through SEM and for their mechanical properties through the flexural strength test, where the pure PP plates showed a mechanical performance 21.7% higher than the composite with 30% residue, for Significance values (P < 0.05) there was no static difference between the plates. The infrared spectrometry patterns indicated that the composition of the vegetal filler is characterized by constituents such as lignin, cellulose and hemicellulose. The results obtained indicated good performance of plastic wood, thus, the objective of this work was achieved.

RESUMO Introdução: o acúmulo de detritos na interface braquete-arco pode influenciar no atrito, mas a limpeza dos braquetes usando jatos de bicarbonato de sódio pode interferir nesse processo. Objetivo: o objetivo desse estudo foi avaliar a força de atrito e a quantidade de detritos remanescentes em braquetes ortodônticos submetidos à profilaxia com jatos de bicarbonato de sódio. Material e Métodos: avaliou-se, ao final do tratamento ortodôntico, a força de atrito e o acúmulo de detritos na superfície de 28 braquetes de pré-molares. Em uma hemiarcada, os braquetes foram jateados com bicarbonato de sódio (n = 14) por 5 segundos, enquanto a hemiarcada contralateral serviu de controle (n = 14). Foram realizados ensaios mecânicos de atrito e análise imagiológica dos braquetes de ambas as hemiarcadas, a jateada e a controle. O teste de Wilcoxon foi utilizado para a análise comparativa entre as hemiarcadas, com p < 0,05. Resultados: os braquetes submetidos à limpeza com jatos de bicarbonato de sódio apresentaram menor atrito (mediana = 1,27N), quando comparados aos do lado controle (mediana = 4,52N) (p < 0,01). A análise imagiológica demonstrou que o grupo controle apresentou maior acúmulo de detritos (mediana = 2,0), em comparação ao grupo que recebeu profilaxia com jatos de bicarbonato (mediana = 0,5) (p < 0,05). Conclusão: a limpeza dos braquetes ortodônticos por meio do jateamento com bicarbonato de sódio reduz significativamente o acúmulo de detritos na superfície deles, bem como os níveis de atrito observados durante a mecânica de deslizamento.

ABSTRACT Introduction: Debris buildup on the bracket-wire interface can influence friction. Cleansing brackets with air-powder polishing can affect this process. Objective: The aim of this study was to evaluate the frictional force and amount of debris remaining on orthodontic brackets subjected to prophylaxis with air-powder polishing. Methods: Frictional force and debris buildup on the surface of 28 premolar brackets were evaluated after orthodontic treatment. In one hemiarch, each bracket was subjected to air-powder polishing (n = 14) for five seconds, while the contralateral hemiarch (n = 14) served as control. Mechanical friction tests were performed and images of the polished bracket surfaces and control surfaces were examined. Wilcoxon test was applied for comparative analysis between hemiarches at p < 0.05. Results: Brackets that had been cleaned with air-powder polishing showed lower friction (median = 1.27 N) when compared to the control surfaces (median = 4.52 N) (p < 0.01). Image analysis showed that the control group exhibited greater debris buildup (median = 2.0) compared with the group that received prophylaxis with air-powder polishing (median = 0.5) (p < 0.05). Conclusion: Cleansing orthodontic brackets with air-powder polishing significantly reduces debris buildup on the bracket surface while decreasing friction levels observed during sliding mechanics.

The possibility of recycling and the favorable mechanical properties of the products have encouraged the study and production of thermoplastic composites from natural fibrous waste. Açaí (cabbage palm) fiber, which is removed from the seed, has been slightly investigated, as compared to what is already known about the fruit pulp. In this study, the influence of açaí fiber as an element of reinforcement in recycled everyday usage thermoplastics using simple, low cost methodology was evaluated. Recycled matrixes of high impact polystyrene and polypropylene were molded by hot compression from which the fiber composites were obtained. The FTIR technique showed that the process was efficient in preventing degradation of the açaí fibers. The influence of the fiber on the mechanical behavior of the recycled matrixes was investigated by microscopic images of compression and impact tests. The results showed better impact performance for the fiber combined with the polymeric matrixes.