Hanna J. Maria

Preparation and characterization of potato starch nanocrystal reinforced natural rubber nanocomposites

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.

Nanocelluloses from jute fibers and their nanocomposites with natural rubber: Preparation and characterization.

Nanocellulose fibers having an average diameter of 50nm were isolated from raw jute fibers by steam explosion process. The isolation of nanocellulose from jute fibers by this extraction process is proved by SEM, XRD, FTIR, birefringence and TEM characterizations. This nanocellulose was used as the reinforcing agent in natural rubber (NR) latex along with crosslinking agents to prepare crosslinked nanocomposite films. The effects of nanocellulose loading on the morphology and mechanics of the nanocomposites have been carefully analyzed. Significant improvements in the Youngs modulus and tensile strength of the nanocomposite were observed because of the reinforcing ability of the nanocellulose in the rubber matrix. A mechanism is suggested for the formation of the Zn-cellulose complex. The three-dimensional network of cellulose nanofibers (cellulose/cellulose network and Zn/cellulose network) in the NR matrix plays a major role in improving the properties of the crosslinked nanocomposites.

Clay nanostructure and its localisation in an epoxy/liquid rubber blend

Different nanoclay concentrations (1–3 phr) were incorporated into an epoxy/carboxyl terminated poly(butadiene-co-acrylonitrile) liquid rubber (CTBN) blend to obtain epoxy/clay/CTBN nanocomposites. Morphological analysis (X-ray diffraction and electron microscopy techniques) of epoxy/clay/CTBN nanocomposites revealed that the clay platelets were largely exfoliated at lower (1 phr) clay concentration. This highly exfoliated portion of the clay platelets was found to easily get inside the CTBN phase during the reaction induced phase separation process in 1 phr clay loaded epoxy/clay/CTBN nanocomposite. However, the intercalated clay platelets in epoxy/clay/CTBN nanocomposites with higher (2, 3 phr) clay concentration, locate in epoxy phase with a tendency to align along the epoxy–CTBN interface which suppresses the coalescence of the rubber particles during phase separation. It was found that the clay nanostructure and localisation among the blend components affect both viscoelastic and mechanical properties of the epoxy/clay/CTBN nanocomposites. The quantitative estimation of constrained epoxy volume confirmed the morphological findings. The thermal degradation behavior of the epoxy/clay/CTBN nanocomposites was found to depend mainly on the dispersion of clay rather than its distribution among the blend components.

Compatibilizing action and localization of clay in a polypropylene/natural rubber (PP/NR) blend

The compatibilizing action of clay in polypropylene (PP)/natural rubber (NR) blends and its effect on mechanical properties have been investigated. PP/NR blend containing organically modified nanoclay, Cloisite 20A, was prepared by melt mixing method, using Haake rheocord-90. The blend composition was fixed at the ratio of 70/30 (PP/NR). By varying the filler loading, Cloisite 20A, mechanical properties (i.e.: tensile strength, elongation at break, Youngs modulus and impact strength) showed a dramatic increase as compared to the unfilled 70/30 (PP/NR) reference blend, which is in agreement with morphological analysis carried out using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dispersed NR domain size was decreased linearly up to 3 μm with the addition of 5 phr of Cloisite 20A to PP/NR blend followed by a levelling off at higher concentrations of the clay addition indicating interfacial saturation. X-ray diffraction analysis and TEM images reveal an intercalated structure for all the compositions of PP/NR/clay nanocomposites. From high resolution TEM we have found that the clay predominantly localizes at the PP continuous phase and at the interface. This preferential localization of the clay has three important effects: (1) suppression of coalescence of the NR domains on account of the physical barrier exerted by the clay platelets, (2) decreased domain size of the dispersed NR phase due to the increased viscosity of the continuous PP phase on account of the localization of the clay in the PP phase (rheological reason). (3) Decrease of interfacial tension between PP an NR on account of the preferential localization of the clay at the blend interface. In fact the behaviour of the clay was analogous to the action of compatibilizers in binary polymer blends.

Rubber Nanocomposites: Latest Trends and Concepts

Rubber nanocomposites have a unique position both in academic and industrial point of view and extensive research studies are progressing in this area. Due to their ever increasing significance, a thorough investigation is necessary especially when the application side is considered. The enhanced surface area and high aspect ratio of nano materials lead to superior matrix/filler interaction and this results in the versatile properties and wide range of applications for the obtained nanocomposites. Nano fillers like layered silicates, carbon nanotubes (CNTs), fullerenes, silica, metallic nanoparticles, metal oxides, polyhedral oligomeric silsesquioxane (POSS), biomaterials, nanodiamonds etc. are used extensively in rubber composites fabrication. In this chapter, attempt has been made to briefly explain the recent advances in the area of nanofillers and their rubber nanocomposites. A thorough survey has been made by giving special emphasis to the filler geometry and composite morphology on one side and the composite properties on the other. Finally the study ends up with novel applications of rubber nanocomposites and the future perspectives in this area.

Extraction of bamboo microfibrils and development of biocomposites based on polyhydroxybutyrate and bamboo microfibrils

This investigation deals with the detailed procedure for the extraction of microfibrils from raw bamboo. The microfibrils obtained from raw bamboo were characterized using scanning electron microscope and the average diameter of the fibrils was found to be 10 μm. These microfibrils were then incorporated into polyhydroxybutyrate (PHB) matrix using conventional plastic processing equipments. The impact strength values of the resulting composites indicate that there is an optimum loading of microfibrils in the PHB matrix, beyond which the effect of fibril loading is not significant.

Polyolefins in Automotive Industry

Polyolefins in automobiles have experienced a great deal of interest in the last twenty years, and their applications have been increasing with a tendency of further growth compared with other materials used in automobiles. The major advantages of polyolefin materials are their functionality, cost-effective manufacturing methods, and comparatively lower fuel consumption. In automobiles, the polymeric materials can be used in the internal and external areas, in the engine section, and in the bodywork. Polyolefin can be shaped easily, their surface can be smooth, and they are chemically resistant, lighter than metals and glass, and are also good insulators. All these good properties make the polyolefin popular in the field of automotive industry.

CHAPTER 1:Natural Rubber-Based Composites and Nanocomposites: State of the Art, New Challenges and Opportunities

The discussion of this chapter begins with the brief historical perspectives of natural rubber (NR); the demand of NR, competition of NR to synthetic rubber (SR) and filled-NR for engineering applications are unveiled in the following sections. Challenges to increase the yield of NR latex will be highlighted subsequently. Opportunities to turn lignin from waste NR wood to filler, binder and extender for replacement of carbon black; marketability of NR as industrial raw materials and the potential to develop NR as the feedstock for polymer architectures are discussed. Finally the mechanical properties and applications of filled-NR and non-filled-NR with micro- to nano-fillers; inorganic- and bio-based fillers are advocated in the last section of the chapter.

Modern Trends and Applications of Solvent/Gas Transport Through Various Polymers and Their Nanocomposites

The transport behavior through polymers has enormous technological importance for a variety of barrier applications. Basic phenomena like diffusion, sorption, and permeation of solvents into elastomers play important roles in different areas of engineering and industry. For the design of polymer materials as successful applications for structural engineering materials, it is crucial to study the significance of polymers in the environment of hazardous solvents, vapors, and temperature. The development of new polymer nanocomposites for membrane application is the largest and most promising area for materials development. The performances of these composites and nanocomposite materials for barrier applications depend on the state of development and technical implementation. An overview of the state-of-the-art applications of polymeric materials in different areas is given in this chapter.

Basic structural and properties relationship of recyclable microfibrillar composite materials from immiscible plastics blends: An introduction

Abstract For suitable sustainable development, plastic materials have to show recycling ability and excellent physical, chemical, and thermal properties to reduce plastic pollution. Recently, incorporation of fibers and the compatibilizer into the plastic matrix has been one of the widely researched areas in polymer technology. A series of fibers and fillers reinforced plastics blends and composites have been produced. Various studies with these plastics blends and composites systems have been performed to predict the performance of a material and recycling ability, in which the effects of blend composition and the morphology of plastics blends and composites have been reported. However, it was found that these composites and blends are not well suited in various perspectives such as recycling, miscibility, compatibility, etc. As a result, a new composite system was introduced in the field of polymer composites, and scientists called these microfibrillar insitu composites (MFCs); the in situ composite was derived from the immiscible blends system. Various studies extensively showed and explained the excellent mechanical, thermal, and crystallization properties of MFCs. The objective of this chapter is to describe the structural and properties relationship of MFCs, which is produced from the in situ generation of fibrils from immiscible blends system.