There is growing interest in developing bio-based products and innovative process technologies that can reduce the dependence on fossil fuel and move to a sustainable materials basis. Biodegradable bio-based nanocomposites are the next generation of materials for the future. Renewable resource-based biodegradable polymers including cellulosic plastic (plastic made from wood), corn-derived plastics, and polyhydroxyalkanoates (plastics made from bacterial sources) are some of the potential biopolymers which, in combination with nanoclay reinforcement, can produce nanocomposites for a variety of applications. Nanocomposites of this category are expected to possess improved strength and stiffness with little sacrifice of toughness, reduced gas/water vapor permeability, a lower coefficient of thermal expansion, and an increased heat deflection temperature, opening an opportunity for the use of new, high performance, lightweight green nanocomposite materials to replace conventional petroleum-based composites. The present review addresses this green material, including its technical difficulties and their solutions. 相似文献
Polymer nanofibers, with diameters in the nanometer range, possess larger surface areas per unit mass and permit easier addition of surface functionalities compared with polymer microfibers. Hence, polymer nanofiber mats are being considered for use as filters, scaffolds for tissue engineering, protective clothing, reinforcement in composite materials and sensors. Although some of these applications are in the development stage, a few have been commercially exploited. Research on polymer nanofibers, nanofiber mats, and their applications has seen a remarkable growth over the last few years. However, a review of the various issues related to these nanofibers has not been published. This article presents a review of the recent trends in the processing methods and characterization techniques for polymer nanofibers. Research challenges and future trends in the processing and characterization of polymer nanofibers are discussed in the article. Five processing methods have been examined in this review, namely drawing, template synthesis, phase separation, self-assembly, and electrospinning. Among these methods, electrospinning has been used to convert a large variety of polymers into nanofibers and may be the only process that has the potential for mass production. The structure, morphology, and geometry of nanofibers and the porosity and tensile properties of nanofiber mats can be investigated through conventional techniques and instruments. But new techniques are needed for the mechanical testing of single nanofibers. Although measurement of mechanical properties such as tensile modulus, strength, and elongation is difficult because of the small diameters of the fibers, these properties are crucial for the proper use of nanofiber mats. 相似文献
In this three part paper, we review the synthesis, morphology, and physical and mechanical properties of IPN's as well as the related pseudo-IPN's in which only one of the polymers is cross-linked. Recent studies have shown that the degree of phase separation achieved in these materials is strongly dependent on the compatibility of blends of the linear polymer constituents of the IPN components, as well as the kinetics of chain extension and the presence of grafting between component polymers in Part 2. We illustrate this by a series of IPN's consisting of a polyurethane and acrylic copolymer. The acrylic is a typical automotive enamel. An enhancement in properties results which is dependent on the amount of grafting and the kinetics of polymerisation. Also discussed in Part 3 are IPN's of a polyurethane and an epoxy, which exhibited a synerigsm in adhesive properties, and IPN's of a RIM polyurethane with several epoxies and unsaturated polyesters. 相似文献
Solid polymer electrolytes are light-weight, flexible, and non-flammable and provide a feasible solution to the safety issues facing lithium-ion batteries through the replacement of organic liquid electrolytes. Substantial research efforts have been devoted to achieving the next generation of solid-state polymer lithium batteries. Herein, we provide a review of the development of solid polymer electrolytes and provide comprehensive insights into emerging developments. In particular, we discuss the different molecular structures of the solid polymer matrices, including polyether, polyester, polyacrylonitrile, and polysiloxane, and their interfacial compatibility with lithium, as well as the factors that govern the properties of the polymer electrolytes. The discussion aims to give perspective to allow the strategic design of state-of-the-art solid polymer electrolytes, and we hope it will provide clear guidance for the exploration of high-performance lithium batteries.
The growing world population, evolving urbanization, and globalization have created more demand for food, which has increased challenges in food safety. Development and innovations in food packaging, one of the most important components in the food industry, is of key importance as food safety issues have gathered tremendous attention of the world. Food packaging is mainly intended to prevent a deterioration in quality of foods and beverages during distribution, sales, and consumption. Polymeric materials have been widely used as packaging materials due to their advantageous characteristics, including excellent mechanical, thermal, and corrosion-resistant properties, a lightweight nature, and ease in production. Polymer composites refer to polymers impregnated with nanomaterials and organic or inorganic compounds. Polymer composites have been applied in the packaging industry to enhance or bestow additional properties to packaging materials. This review summarizes the recent advances in polymer and polymer composites used in food packaging applications. First, progress in the polymers utilized for food packaging, with a focus on biodegradable polymers, will be introduced. Subsequently, the utilities of polymer composites in advanced food packaging will be highlighted and categorized into three classifications of packaging: improved, active, and intelligent packaging. Next, concerns on the relevant safety issues and regulations will be briefly discussed. Finally, an outlook on the future research directions of polymer and polymer composites for food packaging will be provided. 相似文献
This paper reviews recent progress in the fields of non-siliceous mesoporous materials since the year 2002. Several synthetic strategies have been developed in the last two years and non-siliceous mesoporous materials with new compositions, designable structures and controlled morphologies have been obtained. Mesostructured non-silicate metal oxides, metal sulfides, metal phosphates and other composites are very useful candidates in catalysis, electronic materials, and sensors. 相似文献
Very shortly following the discovery of single-walled carbon nanotubes laser-based methods emerged as reliable ways to produce moderate quantities with very consistent composition and properties. They have also proven to be good platforms for the systematic investigation of various synthesis parameters in the hope of better understanding the growth process. Several variations exist with differences such as laser wavelength, number of lasers, background temperature, and target composition. A number of common elements have emerged for the production of both high quality and high yields of SWNT, such as the effectiveness of bimetal catalysts like CoNi and NiY, and the need for high process temperatures and controlling the rate of cooling. Combined with the growing amount of in situ diagnostic and computational modelling data we are slowly making progress towards understanding the growth process. This article will present an overview of recent advancements in laser-based synthesis methods and what information can be extracted about the growth process. 相似文献
