دانلود رایگان مقاله لاتین سلولز میکرو کریستال از سایت الزویر
عنوان فارسی مقاله:
سلولز میکرو کریستال سطح اصلاح شده از پنبه به عنوان مواد افزودنی معدنی بالقوه در کامپوزیت ملات سیمان
عنوان انگلیسی مقاله:
Surface modified microcrystalline cellulose from cotton as a potential mineral admixture in cement mortar composite
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
The development of durable cement mortar composites reinforced with fibers and especially natural fibers is an interesting option available for the construction industry in the areas of thin walls/thin-sheet partitions, building envelope/ceilings flat sheets, roofing tiles and pre-manufactured components. Cellulosic fibers offer a variety of advantages such as wide availability, renewable resource, relatively low cost, no known health hazards, low density, adequate stiffness and strength, variety of morphologies, controllable aspect ratio and surface roughness as well as interfacial compatibility through appropriate chemical modification of the fiber surface. In this context, it is relevant to point out that the use of fique fiber as mineral admixture in cementitious roofing tiles and the effects of natural weathering on the microstructure of the composite was reported [1]. Cement mortar as well as concrete possess enough specific strength, but are brittle in nature. The incorporation of different type and size of fibers into cementitous composite reduces the matrix brittleness and increases the durability, which is proportional to the resistance to crack propagation offered by the fibers that bridge the matrix, thereby effectively transferring the load. Substantial increase in flexural strength, toughness and impact resistance post-reinforcement with cellulosic fibers has been reported [2e4]. Cellulosic fibers are also known to reduce plastic shrinkage [5], decrease the thermal conductivity [6] and improve the acoustic performance by increasing the sound absorption [7]. The use of cellulose nanocrystals to enhance the flexural strength of cementitious materials is also known [8]. Cellulosic fibers typically consist of micro fibrils of macromolecules, which in turn consist of two parts: the amorphous regions characterized by flexibility and crystalline regions that contribute to the specific strength. By the chemical treatment of cellulose fiber, especially acid treatment, most of the amorphous part of the long fiber can be reduced or eliminated. The resultant short fiber that is micrometer in size mostly consists of crystalline regions and is known as microcrystalline cellulose (MCC). It has an elastic modulus of about 150 GPa, which is superior to glass fibers (85 GPa)and aramid fibers (65 GPa) [9,10]. The use of MCC as a mineral admixture in mortar offers better distribution, greater surface area and reactivity and enhanced mechanical performance [11e14]. But the industrial production of natural fiber based cementitious composites is limited due to certain disadvantages such as longterm durability that is caused by alkali attack. The high alkalinity in the cementitious matrix degrades the cellulose fibers besides mineralization resulting in the loss of long term tenacity. In addition, fiber fracture, volume (density) variation due to reversible water absorption (due to continuous variation in the weather conditions) is also observed [15e18]. The key to overcoming these disadvantages is to decrease the water uptake of the cellulose fiber through suitable modification and in this process ensure that the fiber is untouched by the matrix while its surface is still amenable for good interfacial bonding with cement. In this context, hornification of fibers [19], immersion in slurried silica fumes prior to incorporation in the matrix and surface modification are well known [20]. The durability of silane treated eucalyptus kraft pulp cellulose on the durability of fiber-cement composited was reported [21].
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کلمات کلیدی:
Handbook of Nanocellulose and Cellulose Nanocomposites, 2 Volume Set https://books.google.com/books?isbn=3527338667 Hanieh Kargarzadeh, Ishak Ahmad, Sabu Thomas - 2017 - Science Bacterial nanocellulose (BNCs) can be surface acetylated with acetic ... The modified nanofibers showed no structural or morphological changes. Acrylic ... The cellulose types, microcrystalline cellulose or cotton linter cellulose fibers, did not ... [PDF]Full-Text PDF - MDPI www.mdpi.com/2073-4360/9/5/167/pdf by K Li - 2017 May 6, 2017 - composite film modified with microcrystalline cellulose (MCC) and metal nanoclusters (NCs) in this study. ... surface-to-volume ratios than those of conventional nanoparticles [11]. ...... cellulose from waste cotton fabrics. Recent Advances in Polymer Nanocomposites https://books.google.com/books?isbn=1466563729 Sabu Thomas, Gennady Zaikov, Valsaraj - 2009 - Technology & Engineering by the cellulose nanowhiskers due to hydrogen bonding at a certain filler content [91,92, ... with sisal cellulose whisker-filled polyvinyl acetate [77], with cotton cellulose ... filled with whiskers obtained by acid hydrolysis of microcrystalline cellulose [118]. 8.5.4 Surface Modification of Whiskers When cellulose is hydrolyzed by ... Surface modification of cellulose with plant triglycerides for ... link.springer.com/10.1007/s10570-007-9132-1 by TA Dankovich - 2007 - Cited by 60 - Related articles Hydrophobic cotton was achieved by surface modification of the cellulose with triglycerides from several plant oils including soybean, rapeseed, olive and ... Concurrent Cellulose Hydrolysis and Esterification ... - ACS Publications pubs.acs.org/doi/pdf/10.1021/acssuschemeng.5b01489 by S Spinella - 2016 - Cited by 8 - Related articles Dec 28, 2015 - CNCs.22,23 For example, surface modification of purified cotton cellulose was ... coproduct of the reaction, which is similar to microcrystalline. Superhydrophobic surfaces from surface-hydrophobized cellulose ... agris.fao.org/agris-search/search.do?recordID=US201500145543 by Y Wang - 2015 - Cited by 3 - Related articles The cellulose types, microcrystalline cellulose or cotton linter cellulose fibers, did not significantly affect the chemical modification of cellulose fibers, but the ...
