RESUMEN
In this study, a brand-new, easy, and environmentally friendly approach for chemically functionalizing 2,2,6,6-tetramethylpiperidinyloxyl radical (TEMPO)-oxidized cellulose nanofiber (TOCNF) to produce modified cellulose nanofiber (octadecylamine-citric acid-CNF) was proposed. Effects of octadecylamine (ODA)/TOCNF mass ratio on the chemical structure, morphology, surface hydrophobicity and oleophobicity were studied. According to Fourier transform infrared spectroscopy (FTIR) analysis, ODA was successfully grafted onto the TOCNF by simple citric acid (CA) esterification and amidation reactions. Scanning electron microscopy (SEM) showed that a new rough structure was formed on the ODA-CA-CNF surface. The water contact angle (WCA) and the castor oil contact angle (OCA) of the ODA-CA-CNF reached 139.6° and 130.6°, respectively. The high-grafting-amount ODA-CA-CNF was sprayed onto paper, and the OCA reached 118.4°, which indicated good oil-resistance performance. The low-grafting-amount ODA-CNF was applied in a pH-responsive indicator film, exhibiting a colour change in response to the pH level, which can be applied in smart food packaging. The ODA-CA-CNF with excellent water/oil-resistance properties and fluorine-free properties can replace petrochemical materials and can be used in the fields of fluorine-free oil-proof paper.
Asunto(s)
Celulosa , Óxidos N-Cíclicos , Interacciones Hidrofóbicas e Hidrofílicas , Nanofibras , Nanofibras/química , Celulosa/química , Óxidos N-Cíclicos/química , Aminas/química , Ácido Cítrico/química , Agua/química , Espectroscopía Infrarroja por Transformada de Fourier , Flúor/química , Propiedades de SuperficieRESUMEN
Os autores analisam os resultados do tratamento de 60 casos de obstruçao intestinal por cancer colorretal atendidos noPronto-Socorro da Faculdade de Ciencias Medicas da Santa Casa de Sao Paulo (1969 a 1983). A mortalidade global desta serie foi de 23,3//. Analisam tambem os tipos de procedimentos cirurgicos e o prognostico
