Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Abstract

SbstractWhiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

Extraction and characterization of cellulose microfibers from Retama raetam stems

“…The presence of these peaks showed the increase in the percentage of cellulosic components after the removal of non-cellulosic materials by chemical treatments [38] . The absorption peak at ~1734 cm -1 on the spectrum of the untreated sample (a) is attributed to the C=O stretching of the acetyl and uronic ester groups of polysaccharides [9,35] , it is also related to the p-coumeric acids of lignin and/or hemicellulose [25] , the absence of this peak after successive chemical treatments indicates the removal of most of lignin and hemicelluloses from the microfibers. Another indicator of lignin and hemicellulose removal during the chemical treatments is the significant decrease in the intensity of the peak around 1236 cm -1 which is related to the -COO vibration of acetyl groups in hemicellulose and/or the C-O stretching of the aryl group in lignin [28] .…”

“…Its existence as the common material of plant cell walls was first investigated by Braconnot in 1819 [6] and Payen in 1838 [7] . It is a polydispersed linear polymer with a microfibrillar structure composed of poly-b (1→4)-D-glucose units with a syndiotactic configuration [8,9] , found in the cell walls as a network of microfibrils embedded in a non-cellulosic matrix [10] . Several plants are rich in cellulose, i.e.…”

Nanocomposite of cellulose acetate reinforced with nanocrystals modified chemically: Modification with bifunctional reagent

“…Vestena et al has pointed out a decrease of the values of crystallinity when reinforcements from NCPs have been added to PLA. According to the authors, an increase in the content of NCs in the PLA matrix has a direct influence on the number of crystallization nuclei, which causes the impingement of spherulites to occur earlier and this affects the final size of the spherulite crystals.…”

Nanoceluloses De Fontes Alternativas: Obtenção, Morfologias E Aplicações

“…Em suspensão, os nanocristais formam uma dispersão turva, de coloração clara e opalescente, enquanto na forma de filme, após remoção do meio dispersante, forma-se um material de alta transparência e iridescência, cuja extensão dos efeitos depende da concentração da suspensão. NCC podem ser dispersos em meios não-aquosos (VESTENA et al, 2016), entretanto a água é um dos melhores dispersantes tendo em vista a tendência de aglomeração observada em outros meios. Estudos mostraram ainda que a forma de secagem, ou seja, o método usado para remoção do meio dispersante, pode influenciar levemente a estabilidade térmica e a morfologia dos NCC (RÄMÄNEN et al, 2012).…”