Manju Kumari Thakur

Processing and characterization of natural cellulose fibers/thermoset polymer composites

Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental friendliness, flexibility, easy processing and impressive physico-mechanical properties. Natural cellulose fibers based materials are finding their applications in a number of fields ranging from automotive to biomedical. Natural cellulose fibers have been frequently used as the reinforcement component in polymers to add the specific properties in the final product. A variety of cellulose fibers based polymer composite materials have been developed using various synthetic strategies. Seeing the immense advantages of cellulose fibers, in this article we discuss the processing of biorenewable natural cellulose fibers; chemical functionalization of cellulose fibers; synthesis of polymer resins; different strategies to prepare cellulose based green polymer composites, and diverse applications of natural cellulose fibers/polymer composite materials. The article provides an in depth analysis and comprehensive knowledge to the beginners in the field of natural cellulose fibers/polymer composites. The prime aim of this review article is to demonstrate the recent development and emerging applications of natural cellulose fibers and their polymer materials.

Review: Raw Natural Fiber–Based Polymer Composites

The effective utilization of raw natural fibers as indispensable component in polymers for developing novel low-cost eco-friendly composites with properties such as acceptable specific strength, low density, high toughness, good thermal properties, and biodegradability is one of the most rapidly emerging fields of research in polymer engineering and science. In fact, raw natural fiber–reinforced composites are the subject of numerous scientific and research projects, as well as many commercial programs. Keeping in mind the immense advantages of raw natural fibers, in the present article we concisely review raw natural fiber/polymer matrix composites with particular focus on their mechanical properties.

Rapid synthesis of graft copolymers from natural cellulose fibers

Cellulose is the most abundant natural polysaccharide polymer, which is used as such or its derivatives in a number of advanced applications, such as in paper, packaging, biosorption, and biomedical. In present communication, in an effort to develop a proficient way to rapidly synthesize poly(methyl acrylate)-graft-cellulose (PMA-g-cellulose) copolymers, rapid graft copolymerization synthesis was carried out under microwave conditions using ferrous ammonium sulfate-potassium per sulfate (FAS-KPS) as redox initiator. Different reaction parameters such as microwave radiation power, ratio of monomer, solvent and initiator concentrations were optimized to get the highest percentage of grafting. Grafting percentage was found to increase with increase in microwave power up to 70%, and maximum 36.73% grafting was obtained after optimization of all parameters. Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTA/DTG) analysis were used to confirm the graft copolymerization of poly(methyl acrylate) (PMA) onto the mercerized cellulose. The grafted cellulosic polymers were subsequently subjected to the evaluation of different physico-chemical properties in order to access their application in everyday life, in a direction toward green environment. The grafted copolymers demonstrated increased chemical resistance, and higher thermal stability.

Graft copolymers of natural fibers for green composites.

In the present study, free radical induced graft-copolymerization of natural cellulosic polymers (Grewia optiva) has been carried out to develop the novel materials meant for green composites and many other applications. During the graft copolymer synthesis diverse reaction parameters that significantly affect the percentage of grafting were optimized. The structural, thermal and physico-chemical changes in the natural cellulosic polymers based graft copolymers have been ascertained with scanning electron micrography, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and swelling studies. The swelling studies of the grafted cellulosic polymers have been carried out in different solvents to assess the possible applicability of these natural polymers. Green composites were also prepared using raw/grafted cellulosic polymers. It has been found that grafted polymers (Grewia optiva) based green composites gives better tensile properties than the parent natural cellulosic polymers based composites.

Graft copolymers from cellulose: synthesis, characterization and evaluation.

Cellulose, a linear polysaccharide polymer with numerous glucose monosaccharide units is of enormous interest because of its applications in biosorption, biomedical, packaging, biofiltration and biocomposites. In this study, cellulose-graft-poly(butyl acrylate) copolymers were synthesized under microwave conditions. Effects of microwave radiation doses and different reaction parameters were optimized to get the optimum percentage of grafting. The dependence of optimum conditions for better physico-chemical properties of the cellulosic polymers was also determined. Fourier transform infrared spectroscopy (FT-IR) analysis was used to authenticate the chemical reaction taking place between cellulosic polymers and monomer. The thermogravimetric behavior of the raw and grafted cellulosic polymers was characterized by thermogravimetric analysis (TGA). The surface structure of the raw and grafted cellulosic polymers was analyzed through scanning electron microscopy (SEM). The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance.

Surface modification of cellulose using silane coupling agent

Recently there has been a growing interest in substituting traditional synthetic polymers with natural polymers for different applications. However, natural polymers such as cellulose suffer from few drawbacks. To become viable potential alternatives of synthetic polymers, cellulosic polymers must have comparable physico-chemical properties to that of synthetic polymers. So in the present work, cellulose polymer has been modified by a series of mercerization and silane functionalization to optimize the reaction conditions. Structural, thermal and morphological characterization of the cellulose has been done using FTIR, TGA and SEM, techniques. Surface modified cellulose polymers were further subjected to evaluation of their properties like swelling and chemical resistance behavior.

Development of functionalized cellulosic biopolymers by graft copolymerization.

Natural lignocellulosic polymers are one of the most promising biodegradable, non-toxic and eco-friendly polymeric materials which have been used to develop various products for number of applications especially in green composites. However, these cellulosic materials have certain drawbacks, like sensitivity to water and moisture, and need to be modified. So in this article, a treatment of lignocellulose biopolymers with suitable acrylate monomer was investigated. The influence of different reaction parameters on efficiency (grafting) was investigated. SEM, TGA and Fourier transform infrared spectroscopy (FT-IR) were used to study the graft copolymerization between the monomer and hydroxyl groups of lignocellulosic biopolymers. This article also discusses swelling, and chemical resistance properties of the both the grafted/ungrafted cellulosic biopolymer and their potential candidature for green composite applications.

Synthesis of lignocellulosic polymer with improved chemical resistance through free radical polymerization

Rising environmental awareness has resulted in a renewed interest in biological macromolecules obtained from renewable resources. So in view of technological significance of natural lignocellulosic polymers in numerous applications, the present study is an attempt to synthesize lignocellulosic polymers based graft copolymers using free radical polymerization. Different reaction conditions have been studied to synthesize the lignocellulosic graft copolymers. The graft copolymers have been characterized with scanning electron micrography (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The grafted samples have also been screened against different physico-chemical conditions to assess their applicability in different applications.

In-Air Graft Copolymerization of Ethyl Acrylate onto Natural Cellulosic Polymers

The present work deals with the graft copolymerization of ethyl acrylate (EA) onto lignocellulosic natural fibers of the Himalayan region in air in the presence of potassium persulfate (KPS) as initiator. Raw fibers and the graft copolymers after the completion of copolymerization reaction were subjected to evaluation of different properties. Correlation of physicochemical properties with the graft copolymerization reaction mechanism is discussed. Characterization of the graft copolymers was carried out with scanning electron microscopy, Fourier transform-infrared spectrophotometry, and thermogravimetric analysis.

Graft Copolymers from Natural Polymers Using Free Radical Polymerization

The present research work deals with the surface modification of natural cellulosic polymers to develop novel materials for different applications. Natural cellulose-graft-poly (methyl acrylate) copolymers were prepared using the free radical induced graft copolymerization technique. Different reaction parameters were optimized to achieve the highest percentage of grafting of natural cellulose-graft-poly (methyl acrylate) copolymers. The natural cellulose graft copolymers were characterized by FT-IR, SEM, TGA, and physicochemical studies. For the evaluation of swelling and the physicochemical mechanism, swelling and chemical resistance studies were carried out in different solvents as well as chemicals.