Search results for "Cellulose"
showing 10 items of 318 documents
STUDY REGARDING YARN TENSION DURING KNITTING ON CIRCULAR MACHINE WITH SMALL DIAMETER
2015
If yarn tension is controlled properly during knitting, it gives an improved and uniform fabric appearance. The main objective of knitters is to feed yarn to the knitting point at a low and uniform tension. To ensure that the stress do not affect yarn properties, literature recommends that the yarn tension shall be so adjusted that it fits in the field elastic. The value of the yarn stress influences not only quality of knitted product, but also the value of the knitting machine production, by the frequency rupture of yarns. This is influenced directly by the yarn stress and yarn quality. The value of this tension is influenced by a complex of factors, such as: technological diagram of the …
Rheological and Flocculation Analysis of Microfibrillated Cellulose Suspension Using Optical Coherence Tomography
2018
A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was reflected in a monotonously decreasing floc size when the shear stress exceeded the yield stress of the suspension. The quantitative viscous behavior of the MFC suspension changed abruptly at the wall shear stress of 10 Pa, which was reflected in a simultaneous abrupt drop of the floc size. The flocs were strongly elongated with low shear stresses. With the highest shear stresses, the flocs…
Study and evaluation of nano-structured cellulose fibers as additive for restoration of historical mortars and plasters
2017
Abstract UPM bio-fibrils are nano-structured cellulose fibers (nano-fibrils) produced by UPM Kymmene-Corporation, a Finnish company. This paper reports a preliminary study about nano-fibrils to determine their possible use for restoration of historical mortars and plasters. The aim of this study is to investigate the behavior of some mixtures added with nano-fibrils in their properties for conservative purposes. These mixtures reproduce the composition of historical mortars and plasters, made of natural hydraulic lime (NHL 3.5) and river sand. After 28 days of hardening, the properties of specimens with nano-fibrils were compared with untreated one to understand how nano-fibrils interact wi…
Cellulose Nanocrystals from Lignocellulosic Raw Materials
2017
Cellulose nanocrystals (CNCs) are unique, renewable top-down nano particles from which coatings with improved gas barrier properties and new functionalities can be prepared. In this paper, the potential for obtaining such high performing nanocrystals from low-cost lignocellulosic by-products or raw materials is proved by a comparison study on CNCs obtained both from cotton linters and kraft pulp, by means of the ammonium persulfate (APS) process. Morphological and chemical characterization of the nanocrystals obtained, as well as the main functional properties of the poly(ethylene terephthalate) coated films, showed quite similar characteristics and performances of CNCs obtained from pure c…
Aloe-Based Edible Coating to Maintain Quality of Fresh-Cut Italian Pears (Pyrus communis L.) during Cold Storage
2021
Pear fruits are known for their antioxidant and nutritional characteristics. However, they are very susceptible to rapid decay. Edible coating (EC) represents a good strategy to maintain postharvest quality. The effects of two EC in slowing down the senescence processes in fresh-cut ‘Coscia’ pears were investigated: EC1 (A. vera gel, hydroxypropyl-methylcellulose and pomegranate seeds oil (PSO), EC2 (A. vera gel and hydroxypropyl-methylcellulose). Weight loss, firmness and colour decrease more slowly in both EC-treated than in untreated (CTR) slices; soluble solid content increases faster in CTR, indicating a faster ripening process. The specific investigation of undesired microorganisms di…
Thermal degradation of microcrystalline cellulose in concentrated phosphoric acid
2011
The most common renewable fuel is ethanol. It is a liquid produced by fermentation of glucose which is very abundant in cellulose based materials. Bioethanol is achieved in a two-steps process: 1. hydrolysis of the cellulose included in the ligno-cellulosic materials to fermentable reducing sugars; 2. fermentation of such sugars to ethanol. While the second fermentation step, mediated by yeasts or bacteria, is very well established, the first one must be still assessed for process optimization. Many efforts have been made to identify solvents for cellulose in order to develop methods for the achievement of fermentable glucose. In the presence of mineral acid, cellulose undergoes hydrolysis …
Le macchine molecolari deputate alla costruzione e modificazione delle pareti delle cellule vegetali
2015
Le pareti sono uno degli elementi funzionali caratterizzanti delle cellule vegetali, dove biosintesi, assemblaggio e rimodellamento sono sotto stretto controllo genetico e ambientale. La principale macchina molecolare coinvolta è la cellulosa sintasi, la cui attività permette la polimerizzazione degli zuccheri in cellulosa e la cui interazione con il citoscheletro determina l'accrescimento e la forma definitiva delle cellule mature. Altri meccanismi enzimatici sono ad oggi sotto investigazione per comprendere meglio come avvengono la costruzione e le modificazioni di questa struttura cellulare, che garantisce alle piante il necessario sostegno meccanico e fornisce al contempo all'uomo mater…
Thermal Parameters Measurements of High-Rise Building Envelope
2016
In buildings, to ensure the thermal comfort of the occupants and to keep the energy consumption as low as possible, a correct design of the thermal system is necessary. To do so, an appropriate determination of the thermo-physical properties of the wall materials is needed, particularly; new light-weight building technologies are widely used in the construction of the building envelope. One of these parameters, particularly important in Mediterranean climatic dynamic conditions is the heat capacity, due to the presence of the sun’s energy contribution in hot and cold seasons. The value of the heat capacity in such like materials is typically quite different from the declared parameter, obta…
Efficacy and safety of two artificial saliva-based polymers containing 0.1% pilocarpine for treatment of xerostomia: A randomized clinical pilot tria…
2021
Background Topical agents are the mainstay in the treatment of xerostomia, a common complaint most frequently associated with salivary dysfunction. This study aimed to compared the efficacy and safety for xerostomia treatment of 2 artificial saliva preparations containing 0.1% pilocarpine, and, either sodium carboxymethylcellulose (SCMC), or, sodium polyacrylate (SPA). Material and Methods Thirty-one xerostomia patients were randomly allocated into either a SCMC-treated group (15 patients), or, a SPA-treated group (16 patients). The formulations were taken 0.5 ml, 4 times daily for 6 weeks and double-blinded assessed before and after treatments using Xerostomia Inventory (XI) and Clinical O…
Comparison of adsorption equilibrium models and error functions for the study of sulfate removal by calcium hydroxyapatite microfibrillated cellulose…
2017
In the present study, the adsorption of sulfates of sodium sulfate (Na2SO4) and sodium lauryl sulfate (SLS) by calcium hydroxyapatite-modified microfibrillated cellulose was studied in the aqueous solution. The adsorbent was characterized using elemental analysis, Fourier transform infrared, scanning electron microscope and elemental analysis in order to gain the information on its structure and physico-chemical properties. The adsorption studies were conducted in batch mode. The effects of solution pH, contact time, the initial concentration of sulfate and the effect of competing anions were studied on the performance of synthesized adsorbent for sulfate removal. Adsorption kinetics indica…