Cellulose-based composites chemical composition

Fig. 15.1 Schematics of competitive chemical bonds promoted by diisocyanates in all-cellulosic based composites. Chemical coupling between fibers and matrix and cross-linking between anhydroglucose units of the matrix are shown. R refers to an aliphatic or aromatic group. The matrix is hydroxypropylcellulose (HPC)...

Chemical modification with suitable chemicals and innovative technology provides a noble and facile route for the development of intrinsic negative properties of cellulose-based composites materials. Although, the chemical treatments sometimes improved the certain properties composites, however, negative effect also observed. Alkali treatment improved adhesion and compatibility considerably among all conventional... 

Asahi Chemical Industry carried out an exploratory investigation to determine the requirements for cellulose based separators for lithium-ion batteries. In an attempt to obtain an acceptable balance of lithium-ion conductivity, mechanical strength, and resistance to pinhole formation, they fabricated a composite separator (39—85 /cellulosic fibers (diameter 0.5—5.0 /pore diameter 10—200 nm) film. The fibers can reduce the possibility of separator meltdown under exposure to heat generated by overcharging or internal short-circuiting. The resistance of these films was equal to or lower than the conventional polyolefin-based microporous separators. The long-term cycling performance was also very comparable. 

The traditional pulp/paper composition metrics (e.g. specific lignin and cellulose contents) are based on chemical reaction (depolymerization) of the native biomass into fractions. Each separated fiaction is then independently pyrolysed, and the pyrolysis yields are fit to models, and the composite used to predict other woody species ... 

Hon DN-S (1989) Cellulose chemistry and technology. In Schniewind AP (ed) Concise encyclopedia of wood and wood-based materials chemical composition. Pergamon, New York... 

S. Kalia, "Development of polymer matrix based composites using grafted Flax cellulose as reinforcing agent and evaluation of some mechanical and chemical properties" Ph.D. Thesis, Punjab Technical University, Jalandhar, Punjab, 2008. 

Ibach RE, Clemons CM. Biological resistance of polyethylene composites made with chemically modified fiber or flour. Proceedings of the 6th Pacific Rim Bio-based Composites Symposium and Workshop on the Chemical Modification of Cellulosics 2002 Nov 10-13 Portland, OR. Portland (OR) Oregon State University 2002. p 574. 

Flame-retardant textiles are textiles or textile-based materials that inhibit or resist the spread of fire. Factors affecting flammability and thermal behavior of textile include fiber type, fabric construction, thermal behavior of textile polymer and its composition as well as the presence or absence of flame additives. On the other hand, flame-retardant additives can be classified by their chemical composition or by mode of action, i.e., gas phase action or by the formation of protective barrier [49, 50]. Moreover, flame-retardant functional finishes of cellulose-based textiles can be accomplished by [i] using inorganic phosphates, (ii) with organophosphorous compounds, [iii) with sulfur-derivatives or (iv) by grafting flame retardants monomers [49,50]. 

In this chapter we have reviewed some of the most important characteristics of cellulose and cellulose based blends, composites and nanocomposites. The intrinsic properties of cellulose such as its remarkable mechanical properties have promoted its use as a reinforcement material for different composites. It has been showed that cellulose is a material with a defined hierarchy that tends to form fibrillar elements such as elementary fibrils, micro fibrils, and macro fibers. Physical and chemical processes allow us to obtain different scale cellulose reinforcements. Macro fibers, such as lignocellulosic fibers of sisal, jute, cabuya, etc. are used for the production of composites, whereas nano-sized fibers, such as whiskers or bacterial cellulose fibers are used to produce nanocomposites. Given that cellulose can be used to obtain macro- and nano-reinforcements, it can be used as raw material for the production of several composites and nanocomposites with many different applications. The understanding of the characteristics and properties of cellulose is important for the development of novel composites and nanocomposites with new applications. 

The first generation of the NF membranes can be traced back to the early 1970s when most of the membranes were made of cellulose acetate (CA) and other cellulose esters. These cellulose-based membranes, however, severely limited the range of industrial applications due to their poor chemical and biological resistances coupled with insufficient water permeation. This consequently resulted in the development of a second generation of noncellulosic NF-composite membranes made of polyamide (PA) and polyurea (PU) with the aim to improve water permeability and selectivity, together with better pH and solvent stability (Schafer et al. 2003). This section does not intend to provide an exhaustive review of all the NF membranes developed to date. It simply aims to give the latest development of NF membranes in the past decade. Attention is paid to the research and development of NF prepared from two different fabrication techniques. 

Bendahou A, Habibi Y, Kaddami H et al (2009) Physico-chemical characterization of palm from phoenix dactylifera-1, preparation of cellulose whiskers and natural rubber-based composites. J Biobased Mater Bioenergy 3 81-90... 

The opacity is a critical property if the starch-based films are used for food coatings applications. Transparent films are characterized by low values of the area below the absorption curve. The obtained values showed that films with addition of organic acid modified starch microparticles CMSt were more transparent than films with no chemically modified starch [74]. Besides, the opacity of films decreased due to addition of CMSt, this tendency being more noticeable in sample modified with tartaric acid. Film opacity decreased in order TAMSt/Stcellulose filler composite samples is represented [75]. 

Chemical Modification and Properties of Cellulose-Based Polymer Composites... 

Chemical modification is an often followed route to improve specific characteristic properties of cellulose-based polymer composite materials. In this chapter, several types of chemical modifications along with the incorporation of nanocaly into cellulose-based materials are described, and their effect on the structural and mechanical properties of the resulting composites are discussed. All chemical treatments are intended to improve at least one property of the composites. They can, however, have a positive or negative impact on other composite properties. Interaction, adhesion and compatibility between the cellulose fiber and the polymer are the main concerns of chemical treatment. Furthermore, chemical modification reduces -OH groups from the cellulose fiber surface. 

Among various chemical treatments, alkali treatment with NaOH solution is often chosen to modify cellulose-based materials. Since NaOH reacts with -OH groups of cellulose and reduces hydrophilicity and impurities from cellulose fiber, it improves the compatibility between the cellulose and the polymer matrix. Consequently, significant improvement in the mechanical and morphological properties of composite such as MOE, MOR, compressive modulus, SEM morphology and XRD pattern are observed for the alkali-treated composite materials. Benzene diazonium salt is also an important chemical, which reacts with cellulose in fiber and produces 2,6-diazo cellulose by a coupling reaction. 

Also discussed in this chapter are the influence of other chemical treatments on the physical and mechanical properties of cellulose-based materials andthe effect of nanoclay on the morphological and mechanical properties of polymer composite. 

In this chapter, various types of chemical treatments including alkali, benzene diazonium salt, o-hydroxybenzene diazonium salt, succinic anhydride, maleic acid, acrylonitrile and nanocaly onto cellulose-based materials will be described and their effect on the structural and mechanical properties of the resultant composites will also be discussed. 

Cellulose-based natural fiber can be oxidized using oxidizing agent with acidic catalyst. Oxidation reactions applied to cellulose in fiber for chemical modifications [43]. Oxidation reactions occur on cellulose selectively at particular position. The reaction of sodium metaperiodate with cellulose in wood fiber in the presence of sulfuric acid catalyst at 120°C and 85 KPa pressure yielded the oxidized product. Sodium metaperiodate reacts with hydroxyl groups of cellulose and produce 2,3-dialdehyde cellulose which improved the physical and mechanical properties of polymer composites [44]. 

Cellulose-Based Polymers for Packaging Applications 483 Table 21.1 Chemical composition of some common natural vegetable fibers. 

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