RESUMO
Cellulose micro/nanofibril (MNFC) films are an interesting alternative to plastic-based films for application in biodegradable packaging. In this study, we aimed to produce and characterize MNFC films obtained from alkaline-pretreated rubberwood (Hevea brasiliensis) waste and Eucalyptus sp. commercial pulp. MNFC and films were evaluated regarding microstructure; crystallinity; stability; and physical, optical, mechanical, and barrier properties. A combined quality index (QI) was also calculated. Eucalyptus MNFC suspensions were more stable than H. brasiliensis. Both films had a hydrophobic surface (>90°) and high grease resistance (oil kit 12). H. brasiliensis films had lower transparency (26.4 %) and high crystallinity (â¼89 %), while Eucalyptus films had lower permeability and higher mechanical strength. The QI of MNFC was 51 ± 5 for H. brasiliensis and 55 ± 4 for Eucalyptus, showing that both types of raw material have potential for application in the packaging industry and in the reinforcement of composites, as well as for high value-added applications in products made from special materials.
Assuntos
Celulose , Hevea , Nanofibras , Celulose/química , Hevea/química , Nanofibras/química , Permeabilidade , Eucalyptus/química , Embalagem de Produtos , Resistência à Tração , Interações Hidrofóbicas e HidrofílicasRESUMO
The development of packaging films made from renewable raw materials, which cause low environmental impact, has gained attention due to their attractive properties, which have become an exciting option for synthetic films. In this study, cellulose micro/nanofibrils (MFC/NFC) films were produced with forest residues from the Amazon region and evaluated for their potential to generate alternative packaging to traditional plastic packaging. The MFC/NFC were obtained by mechanical fibrillation from fibers of açaí seeds (Euterpe oleracea), titica vine (Heteropsis flexuosa), and commercial pulps of Eucalyptus sp. for comparison. The fibrillation of the titica vine culminated in higher energy expenditure on raw materials. The açaí films showed a higher tensile strength (97.2 MPa) compared to the titica films (46.2 MPa), which also showed a higher permeability rate (637.3 g day-1 m-2). Films of all raw materials scored the highest in the grease resistance test (n° 12). The films produced in the study showed potential for use in packaging for light and low moisture products due to their adequate physical, mechanical, and barrier characteristics. New types of pre-treatments or fibrillation methods ecologically correct and viable for reducing energy consumption must be developed, mainly for a greater success of titica vine fibrillation at the nanoscale.
RESUMO
Using mineral and agro-industrial wastes associated with the cement matrix can add value and guarantee suitable properties for reinforced composites. This research aimed to evaluate the effect of the incorporation of quartzite and coconut fibers on masonry blocks' physical, mechanical, and thermal properties. Quartzite was evaluated replacing 0%, 25%, 50%, 75%, and 100% of the sand, whereas the coconut fibers were added in a proportion of 2.5% of the volume of gravel. Quartzite residues were analyzed regarding their granulometry, chemical composition, and pozzolanicity. The block initial formulation (control) was: 8.2% cement, 45.9% sand, and 45.9% gravel. The cement was cured at room temperature for 28 days. Subsequently, the blocks were subjected to the characterization of physical, mechanical, and thermal properties. Coconut fibers presented a low percentage of extractives, with a low inhibition index (1.93%), reducing their effect on cement hardening. The increase in the content of quartzite incorporated provided a reduction in bulk density and an increase in porosity (from 11.7 to 16.0%) and water absorption after 24 h (from 7.0 to 8.5%). The compressive strength was reduced from 50% with the insertion of the quartzite. The quartzite and coconut fibers reduced the concrete's thermal conductivity, providing essential reflections for the performance of the blocks in terms of thermal comfort in built environments. Further, incorporating these materials provided the potential to obtain blocks with characteristics of resistance and offering possible thermal comfort, besides contributing as an option for a destination for these mineral and agro-industrial wastes.