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Banana fibers are an agricultural waste material with a great exploitation potential due to their cellulose-rich content. Raw banana fibers (RBF) were treated with 3-aminopropyltriethoxy silane and glycidoxypropyltrimethoxy silane to improve the inherent limitations of banana fibers, namely its poor cell adhesion. The fibers’ modification was evaluated by inverse gas chromatography (IGC). Similar γ values were observed between the RBF and silane-treated fibers (39–41 mJ/m2), which indicates similar reactivity towards apolar probes. However, the decrease in the entropic parameter indicates the silane covalent bonding with the cellulose chains making a stiffer structure. Organosilane grafting was confirmed by an increased basic character in the silane-treated fibers (Kb/Ka from 1.03 to 2.81). The surface morphology also changed towards higher contact area (SBET increases 6.7 times) and porosity (Dp increases up to 67%). Both morphological and functional group reactivity changes suggest that the organosilane treatment offers new opportunities for these fibers to be used as adsorbents for proteins as well as to cell adhesion. Therefore, IGC proved a simple and viable technique in the characterization of silane-treated fibers.

Biodegradable colourimetric films incorporating anthocyanins which can respond to food spoilage is a novel and green development in packaging field. However, when it comes to commercial applications, these biodegradable matrices lack sufficient mechanical strength and water resistivity. Hence nanomaterials are being incorporated into the matrix to improve its properties. The aim of this work was to develop intelligent starch based biopolymer film by incorporating carbon dot (CD) and anthocyanin extracted from clitoria ternatea flower (CTE). The starch/CD/CTE film (SED) was prepared by solution casting technique and characterised as novel, high sensitive, pH indicator film having the potential to monitor the freshness of packed pork. SEM, FTIR and XRD analysis showed homogenous distribution of CD and CTE in starch matrix. SED films exhibited highest mechanical, barrier, thermal and antioxidant properties due to synergistic effect of CD and CTE. Besides, SED films exhibited colour variations in different pH due to the presence of anthocyanin in CTE. Hence SED film was used as a low cost visual indicator for monitoring freshness of packed pork sample. The film showed visual colour changes from purple to green as storage time increased. This study shows that food grade ingredients can be used to prepare active smart films which can in turn be used to monitor the freshness of food product like pork.

International audience; Natural rubber (NR)/carbon nanotube (CNT) composites containing ionic liquid (IL) at different concentrations have been prepared by using an internal mixer in the conventional mechanical mixing method. The role of a green solvent IL 1-butyl-3-methyl imidazolium chloride (BMIC) on the curing kinetics, mechanical, morphological and thermal properties of NR-CNT composites has been studied. It has been found that BMIC strongly influenced rheometric data and mechanical properties. The addition of the IL (1-ethyl-3-mehylimidazolium chloride) significantly increased the vulcanization rate, decreased scorch and cure times. The plasticizing effect of IL on the composite is well understood from the results of different analysis. The increment in the free volume of the nanocomposites by the effect of IL was studied using positron annihilation lifetime spectroscopy. The mechanical properties such as tensile strength and elongation at break increased with small amount of IL. With high amount of IL, tensile strength and elongation at break decreased due to plasticizing effects, contributing towards retarding the strain-induced crystallization in NR/CNT/IL composites. Differential scanning calorimetry analysis was done and the improvement in dispersion of the CNTs by the addition of IL has been investigated through transmission electron microscopy analysis.

Starch, as an agro-sourced polymer, has received much attention recently due to its strong advantages such as low cost, wide availability, and biodegradability. In this chapter the different steps in the processing of starch based aerogels are discussed. We also focus on the morphological properties by discussing the porosity and SEM analysis of starch aerogels.

Cellulose nanofibres (CNF) with diameter 10–60 nm were isolated from raw banana fibres by steam explosion process. These CNF were used as reinforcing elements in natural rubber (NR) latex along with cross linking agents to prepare nanocomposite films. The effect of CNF loading on the mechanical and dynamic mechanical (DMA) properties of NR/CNF nanocomposite was studied. The morphological, crystallographic and spectroscopic changes were also analyzed. Significant improvement of Young’s modulus and tensile strength was observed as a result of addition of CNF to the rubber matrix especially at higher CNF loading. DMA showed a change in the storage modulus of the rubber matrix upon addition of CNF which proves the reinforcing effect of CNF in the NR latex. A mechanism is suggested for the introduction of the Zn–cellulose complex and its three dimensional network as a result of the reaction between the cellulose and the Zinc metal which is originated during the composite formation.

Biodegradable nanocomposite films were prepared by incorporation of cellulose nanofibrils (CNF) into alginate biopolymer using the solution casting method. The effects of CNF content (2.5, 5, 7.5, 10 and 15 wt %) on mechanical, biodegradability and swelling behavior of the nanocomposite films were determined. The results showed that the tensile modulus value of the nanocomposite films increased from 308 to 1403 MPa with increasing CNF content from 0% to 10%; however, it decreased with further increase of the filler content. Incorporation of CNF also significantly reduced the swelling percentage and water solubility of alginate-based films, with the lower values found for 10 wt % in CNF. Biodegradation studies of the films in soil confirmed that the biodegradation time of alginate/CNF films greatly depends on the CNF content. The results evidence that the stronger intermolecular interaction and molecular compatibility between alginate and CNF components was at 10 wt % in CNF alginate films.

Cellulose was extracted from lignocellulosic fibers and nanocrystalline cellulose (NC) prepared by alkali treatment of the fiber, steam explosion of the mercerized fiber, bleaching of the steam exploded fiber and finally acid treatment by 5% oxalic acid followed again by steam explosion. The average length and diameter of the NC were between 200-250 nm and 4–5 nm, respectively, in a monodisperse distribution. Different concentrations of the NC (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5% by weight) were dispersed non-covalently into a completely bio-based thermoplastic polyurethane (TPU) derived entirely from oleic acid. The physical properties of the TPU nanocomposites were assessed by Fourier Transform Infra-Red spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Dynamic Mechanical Analysis (DMA) and Mechanical Properties Analysis. The nanocomposites demonstrated enhanced stress and elongation at break and improved thermal stability compared to the neat TPU. The best results were obtained with 0.5% of NC in the TPU. The elongation at break of this sample was improved from 178% to 269% and its stress at break from 29.3 to 40.5 MPa. In this and all other samples the glass transition temperature, melting temperature and crystallization behavior were essentially unaffected. This finding suggests a potential method of increasing the strength and the elongation at break of typically brittle and weak lipid-based TPUs without alteration of the other physico-chemical properties of the polymer.

The objective of this work was to develop a simple process to obtain an aqueous stable colloid suspension of cellulose nano fibrils from various lignocellulosic fibres. For the preliminary analysis we have studied three different fibres: banana (pseudo stem), jute (stem) and pineapple leaf fibre (PALF). To study the feasibility of extracting cellulose from these raw fibres we have adopted steam explosion technique along with mild chemical treatment. These processes included usual chemical procedures such as alkaline extraction, bleaching, and acid hydrolysis but with a very mild concentration of the chemicals. The chemical constituents of the fibre in each processing step were determined by ASTM standard procedures. Morphological, spectroscopic and thermal analyses of the fibres were carried out and found that the isolation of cellulose nanofibres occurs in the final step of the processing stage and they possess improved thermal stability for various advanced nanotechnological applications.

Steam explosion process is employed for the successful extraction of cellulose nanofibrils from pineapple leaf fibres for the first time. Steam coupled acid treatment on the pineapple leaf fibres is found to be effective in the depolymerization and defibrillation of the fibre to produce nanofibrils of these fibres. The chemical constituents of the different stages of pineapple fibres undergoing treatment were analyzed according to the ASTM standards. The crystallinity of the fibres is examined from the XRD analysis. Characterization of the fibres by SEM, AFM and TEM supports the evidence for the successful isolation of nanofibrils from pineapple leaf. The developed nanocellulose promises to be a very versatile material having the wide range of biomedical applications and biotechnological applications, such as tissue engineering, drug delivery, wound dressings and medical implants.

Polypropylene (PP)/banana fiber (BF) composites were fabricated from PP fiber and short BF by novel commingling method. The dynamic mechanical analysis (DMA) of the composites was performed with reference to BF loading and fiber surface treatments. By the incorporation of BF into the PP matrix, the storage modulus and loss modulus have been found to increase, whereas damping factor has been found to decrease. Glass transition temperature was found to increase with increase in BF loading. The viscoelastic properties of the composites were also found to depend on fiber surface treatments. The activation energy of the composites for the glass transition has been found to be increased by the increase in BF loading. Surface treatment of the BF further increased the activation energy of the composites, indicating a stronger interface for treated fiber composites. Scanning electron microscopy (SEM) photographs of the BF showed the physical changes induced by the surface treatments. Fourier transform infrared spectroscopy (FTIR) was used to ascertain the existence of the type of interfacial bonds. The use of theoretical equations to predict the storage modulus has also been discussed. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Alkali treatment coupled with high pressure defibrillation and acid treatment have been tried on banana fibers obtained from the pseudo stem of the banana plant Musa sapientum. The structure and morphology of the fibers have been found to be affected on the basis of the concentration of the alkali and acid and also on the pressure applied. Steam explosion in alkaline medium followed by acidic medium is found to be effective in the depolymerization and defibrillation of the fiber to produce banana nanowhiskers. The chemical constituents of raw and steam exploded fibers were analyzed according to the ASTM standards. Structural analysis of steam exploded fibers was carried out by FTIR and XRD. The fiber diameter and percentage crystallinity of the modified fibers were investigated using X-ray diffraction studies. Characterization of the fibers by SFM and TEM supports the evidence for the development of nanofibrils of banana fibers.

Using a Dynamic Mechanical Analyzer (DMA), mechanical properties like modulus and phase transition temperature of polyester composites of banana fibers (treated and untreated) are measured simultaneously. The shifting of phase transition temperature is observed in some treatments. The performance of the composite depends to a large extent on the adhesion between polymer matrix and the reinforcement. This is often achieved by surface modification of the matrix or the filler. Banana fiber was modified chemically to achieve improved interfacial interaction between the fiber and the polyester matrix. Various silanes and alkalies were used to modify the fiber surface. Chemical modification was found to have a profound effect on the fiber/matrix interaction, which is evident from the values of phase transition temperatures. Of the various chemical treatments, simple alkali treatment with 1% NaOH was found to be the most effective.

Corn starch nanocrystals were found to serve as an effective reinforcing agent for natural rubber (NR). Starch nanocrystals were obtained by the sulfuric acid hydrolysis of starch granules. After mixing the latex and the starch nanocrystals, the resulting aqueous suspension was made into coagulum and then it is mixed with the dry NR and cross linking agents, in two roll mill followed by compression molding. The composite samples were prepared by varying filler loadings, using a colloidal suspension of starch nanocrystals and NR latex and dry rubber. The morphology of the nanocomposites prepared was analyzed by Field Emission Scanning Electron Microscopy (FESEM) and FESEM analysis revealed the size and shape of the crystal and their homogeneity dispersion in the composites. The crystallinity of the nanocomposites was studied using XRD analysis which indicated an overall increase in crystallinity with increased in filler content. The mechanical properties of the nanocomposites such as stress-strain behaviour, tensile strength, tensile modulus and elongation at break were measured according to ASTM standards. The tensile strength and modulus of the composites were found to improve tremendously with increasing nanocrystal content. This dramatic increase observed in the modulus and the tensile strength can be attributed to the formation of starch nanocrystal network. This network immobilizes the polymer chains leading to an increase in the modulus and other mechanical properties. The DMA studies of the composites were carried out and it reveals the effective reinforcing mechanism of starch nanocrystal on NR matrix.

With the environmental appeal around the planet for a sustainable development, there is the need to develop new materials from renewable resources, which can be degraded in a short time in the environment, thereby maintaining the proper balance of the carbon cycle. Biopolymers from various natural botanical resources can act as a substitute for petroleum-based synthetic polymers because of their low cost, ease of availability, and biodegradability along with other organic wastes to soil humic materials. Materials which are biodegradable and fully sustainable are termed as “Green Composites”. This development not only solves the white pollution problem but also stops the overdependence on petroleum products. Development of Green Composites made from soy protein and starch has been a great challenge for the scientific community, since these materials do not possess all the desirable characteristics of the synthetic polymers, being mostly often, highly hydrophilic and also presenting poor mechanical properties to be used as engineering’s materials. Cellulose macro- and nano-fibers can be used as reinforcement in composite materials to enhance mechanical, thermal, and biodegradation properties of the composites. In this chapter we will be dealing mainly with the preparation, properties, and applications of cellulose fiber-reinforced green composites based on soy protein and starch.

The role of fibre/matrix interactions in chemically modified banana fibre composites were investigated using dynamic mechanical analysis and compared with those of untreated fibre composites. The dynamic modulus value and damping parameter, used to quantify interfacial interaction in composites were investigated with special reference to the effect of temperature and frequency. Increased dynamic modulus values and low damping value show the improved interactions between the fibre and the matrix. The damping peaks were found to be dependent on the nature of chemical treatment. Both storage modulus and damping values measured experimentally are consistent and point to the effectiveness of silane A174 coupling agent (γ-methacryloxypropyl trimethoxy silane) for improving fibre–matrix adhesion. Activation energy values for the transitions of the composites were determined from Arrhenius plots. Cole–cole plots were made to evaluate the heterogeneity of the system.

Banana fibers obtained from the sheath of the banana plant (Musa Sapientum) whose major constituent is cellulose were modified using various chemical agents in order to improve their compatibility with the polymer matrix. The change in the surface composition of the raw and chemically modified fiber was investigated using various techniques such as solvatochromism, electrokinetic measurements, and XPS. Surface characterization by XPS showed the presence of numerous elements on the surface of the fiber. Investigation of the surface after alkali treatment on the other hand showed the removal of most of the elements. Silane treatment was found to introduce a considerable amount of silicon on the surface of the fiber. The [O]/[C] ratio was found to decrease in all cases except for the fluorinated and vinyl silane treated fibers. Detailed investigation of the deconvoluted C 1s spectra revealed the change in the percentage atomic concentration of the various elements on the fiber surface. The dissolution of the various surface components by alkali treatment, which was earlier revealed by SEM, was further confirmed by XPS. The XPS results were found to perfectly agree with the solvatochromic and electrokinetic measurements.

Natural fibers are replacing synthetic fibers as reinforcement in various matrices. The composites so prepared can effectively be used as a substitute for wood and also in various other technical fields like automobile parts. However, to improve the adhesion between the fiber and matrix, chemical modification is suggested. The effect of chemical modification on the dynamic mechanical properties of banana fiber reinforced polyester composites has been analyzed to investigate the interfacial properties. The interfacial phenomenon in turn was found to be related to the acid base interactions involved, which occur due to the specific interactions between less reactive functional groups of each partner at the interface. The acid base interactions were investigated, by solvatochromy and the zeta potential measurements. Solvatochromy revealed that the overall polarity parameter was highest for the silane A151 (vinyl tri ethoxy silane) treated fiber, compared to other treatments. ζ-Potential measurements of the untreated and variously treated fibers also showed that the chemical modification alters the polarity of the already acidic cellulose fibers. The observations of the solvatochromic measurements and ζ-potential measurements are consistent. The results of the polarity parameters were correlated with the results of dynamic mechanical analysis. The storage modulus value was found to be the highest for the silane A151 treated fiber composite.

Changes in the surface composition of chemically treated cellulose fibres obtained from the sheath of banana plants were investigated using electrokinetic (ζ-potential) measurements. Scanning electron microscopy (SEM) was used to observe changes in the surface morphology of the fibres. Spectroscopic methods were also used to analyse the changes on the cellulose fibre surface. Chemical treatments such as alkali treatment, acetylation, treatment with a triazine coupling agent, various silanes, etc. reduced the hydrophilicity of the fibres. The surface morphology of the fibres showed considerable changes. Chemical treatments reduced the acidity of the already polar cellulose fibre. The high iso-electric point (IEP) of the silane A1100-treated fibres shows that basic groups dominate at these surfaces. The observations are consistent with the values obtained using solvatochromic measurements.

Isolation of cellulose nanofibers from renewable resources is becoming an important area of research. The use of these novel nature-based materials has garnered interest from the scientific community because of their high strength and stiffness combined with low weight, biocompatibility, and renewability. The nanodimensions of cellulose fibrils result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. In this context, cellulose nanofibers from banana plant have attracted much interest due to its potential use as a reinforcing agent in novel eco-friendly nanocomposite preparation. This chapter introduces the current knowledge on the extraction of nanocellulose from banana plant and the different characterization techniques employed to understand the reinforcing potential of these nanofibers.

The surface polarity of organically functionalized cellulose fibers has been characterized with linear solvation energy relationships. The Kamlet–Taft hydrogen-bond-donating ability, the hydrogen-bond-accepting ability, the dipolarity/polarizability, Gutman's acceptor number (an indicator of the electron-accepting ability), and Reichardt's ET (30) parameter have all been used to quantitatively represent the polarity of the chemically treated and untreated fiber surfaces. Three different probe dyes, cis-dicyanobis(1,10-phenanthroline)-iron(II), Michler's ketone, and aminobenzodifuranone, have been used as indicators to measure the polarity with correlation analysis of the energy of the ultraviolet–visible absorption maxima. Solvatochromic methods have been proven to be effective in characterizing chemically modified lignocellulosic fibers. Different silanes, NaOH, and long alkyl groups, used to modify the cellulose fiber surface, have changed the hydrogen-bond-donating ability of the fiber. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2546–2553, 2000

Potato starch nanocrystals were found to serve as an effective reinforcing agent for natural rubber (NR). Starch nanocrystals were obtained by the sulfuric acid hydrolysis of potato starch granules. After mixing the latex and the starch nanocrystals, the resulting aqueous suspension was cast into film by solvent evaporation method. The composite samples were successfully prepared by varying filler loadings, using a colloidal suspension of starch nanocrystals and NR latex. The morphology of the nanocomposite prepared was analyzed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM analysis revealed the size and shape of the crystal and their homogeneous dispersion in the composites. The crystallinity of the nanocomposites was studied using XRD analysis which indicated an overall increase in crystallinity with filler content. The mechanical properties of the nanocomposites such as stress-strain behavior, tensile strength, tensile modulus and elongation at break were measured according to ASTM standards. The tensile strength and modulus of the composites were found to improve tremendously with increasing nanocrystal content. This dramatic increase observed can be attributed to the formation of starch nanocrystal network. This network immobilizes the polymer chains leading to an increase in the modulus and other mechanical properties.

Cellulose nanofibers and their composites offer a highly attractive research line in recent times. Cellulose nanofibers have generated a great deal of interest as a source of nanometer-sized fillers because of their sustainability, easy availability, and the related characteristics such as a very large surface-to-volume ratio, outstanding mechanical, electrical, and thermal properties. This chapter describes the many processes to produce nanocellulose from different cellulosic sources and how to increase the compatibility between cellulosic surfaces and a variety of plastic materials. Furthermore, it provides knowledge of different nanocelluloses and nanocomposites and provides updated information on their properties and also deals with fascinating high-tech applications, especially in the medical field.

Green composites constitute a loosely defined family of materials which are obtained from renewable resources and are degradable through action of living organisms. These materials offer a possible alternative to traditional non-biodegradable materials where recycling is unpractical or not economical. Renewable sources of polymeric materials offer an answer to maintaining sustainable development of economically and ecologically attractive technology. When a biodegradable material (neat polymer, blended product, or composite) is obtained completely from renewable resources we may call it a green polymeric material. Nature provides an impressive array of polymers which are generally biodegradable, and which have the potential to replace many current polymers as biodegradation is part of the natural biogeochemical cycle. Natural polymers, such as proteins, starch, chitin and cellulose are examples of such polymers. In addition, Natural rubber latex (NR) Poly lactic acid (PLA) from corn and polyalkanoates (PHA) from bacteria are other green polymers.Green nanomaterials or bio nanomaterials could be easily prepared from animals and plants. These nano sized materials’ properties are comparable to perfect crystals. In most cases, aqueous suspensions of these nano crystallites are prepared by simple mechanical stirring and acid hydrolysis process. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. During the past decade, many studies have been devoted to mimic biocomposites by blending natural bionanomaterials with various polymer matrices. In this chapter, the recent advances on the preparation and characterization of different type of green nano materials and their polymer nanocomposites are discussed and reported. Macro micro and nanocomposites based on fully renewable polymers (which can be called fully green composites) and their applications are discussed in detail.

In this work, cellulose nanofibers were extracted from banana fibers via a steam explosion technique. The chemical composition, morphology and thermal properties of the nanofibers were characterized to investigate their suitability for use in bio-based composite material applications. Chemical characterization of the banana fibers confirmed that the cellulose content was increased from 64% to 95% due to the application of alkali and acid treatments. Assessment of fiber chemical composition before and after chemical treatment showed evidence for the removal of non-cellulosic constituents such as hemicelluloses and lignin that occurred during steam explosion, bleaching and acid treatments. Surface morphological studies using SEM and AFM revealed that there was a reduction in fiber diameter during steam explosion followed by acid treatments. Percentage yield and aspect ratio of the nanofiber obtained by this technique is found to be very high in comparison with other conventional methods. TGA and DSC results showed that the developed nanofibers exhibit enhanced thermal properties over the untreated fibers.

Steam explosion technique was used to isolate banana fibrils from banana fiber. The surface polarity of banana fiber, banana fibril, and chemically-treated banana fibril was investigated by ultraviolet/visible spectroscopy using solvatochromic probe dye molecules. The empirical Kamlet-Taft solvatochromic polarity parameters such as hydrogen bond donating ability HBD (alpha), hydrogen bond accepting ability HBA (beta), the dipolarity (pi*), Gutman acceptor number, and Reichardts ET(30) values for the banana fiber, banana fibril, and chemically-treated banana fibril were determined. It was observed that banana fibril has higher HBD value than banana fiber. Chemical treatment of the banana fibril has lowered the HBD value. The results of the empirical polarity parameters determined were found to be consistent with the results of electrokinetic measurements. The functional groups on the surface of banana fiber, banana fibril, and chemically-treated banana fibril was further analyzed using Fourier transform infrared spectroscopy (FTIR). FTIR spectra revealed the dissolution of the various components from the banana fiber after steam explosion which was further confirmed by scanning electron microscopy.

Pineapple leaf fiber (PALF) which is rich in cellulose, abundantly available, relatively inexpensive, low density, nonabrasive nature, high filling level possible, low energy consumption, high specific properties, biodegradability and has the potential for polymer reinforcement. The utilization of pineapple leaf fiber (PALF) as reinforcements in thermoplastic and thermosetting resins in micro and nano form for developing low cost and lightweight composites is an emerging field of research in polymer science and technology. In this paper we examines the industrial applicabiliy of PALF, mainly for production of composite materials and special papers, chemical feedstocks (bromelin enzyme) and fabrics.