Natural fiber composites interface

One of the most important focus areas of research in the development of natural fiber-reinforced polymer composites is characterisation of the fiber-matrix interface, since the interface alone can have a significant impact on the mechanical performance of the resulting composite materials, in terms of the strength and toughness. The properties of all heterogeneous materials are determined by component properties, composition, structure and interfacial interactions [62]. There have been a variety of methods used to characterize interfacial properties in natural fiber-reinforced polymer composites, however, the exact mechanism of the interaction between the natural fiber and the polymeric matrix has not been clearly studied on a fundamental level and is presently the major drawback for widespread utilization of such materials. The extent of interfacial adhesion in natural fiber-reinforced polymer composites utilizing PLA as the polymer matrix has been the subject of several recent investigations, hence the focus in this section will be on PLA-based natural fiber composites. 

A. Dufresne, Preparation of cellulose nanocomposite, in Interface engineering of natural fiber composites for maximum performance, Chapter 3, N. E. Zaferiropoulos (Ed.), pp. 82-116, Woodhead Publishing in Materials, Philadelphia, USA. (2011). 

Proper characterization of composite interfaces, whether it is for chemical, physical or mechanical properties, is extremely difficult because most interfaces with which we are concerned are buried inside the material. Furthermore, the microscopic and often nanoscopic nature of interfaces in most useful advanced fiber composites requires the characterization and measurement techniques to be of ultrahigh magnification and resolution for sensible and accurate solutions. In addition, experiments have to be carried out in a well-controlled environment using sophisticated testing conditions (e.g. in a high vacuum chamber). There are many difficulties often encountered in the physico-chemical analyses of surfaces. 

The study and application of composite materials are a truly interdisciplinary endeavor that has been enriched by contributions from chemistry, physics, materials science, mechanics and manufacturing engineering. The understanding of the interface (or interphase) in composites is the central point of this interdisciplinary effort. From the early development of composite materials of various nature, the optimization of the interface has been of major importance. While there are many reference books available on composite materials, few of them deal specifically with the science and mechanics of the interface of fiber reinforced composites. Further, many recent advances devoted solely to research in composite interfaces are scattered in different published literature and have yet to be assembled in a readily accessible form. To this end this book is an attempt to bring together recent developments in the field, both from the materials science and mechanics perspective, in a single convenient volume. 

The performance characteristics of a composite material depend on the type of reinforcing fiber (its strength and stiffness), its length, fiber volume fraction in the matrix, and the strength of the fiber-matrix interface. The presence of voids and the nature of the matrix are additional but minor factors. 

The 1-D concentric cylinder models described above have been extended to fiber-reinforced ceramics by Kervadec and Chermant,28,29 Adami,30 and Wu and Holmes 31 these analyses are similar in basic concept to the previous modeling efforts for metal matrix composites, but they incorporate the time-dependent nature of both fiber and matrix creep and, in some cases, interface creep. Further extension of the 1-D model to multiaxial stress states was made by Meyer et a/.,32-34 Wang et al.,35 and Wang and Chou.36 In the work by Meyer et al., 1-D fiber-composites under off-axis loading (with the loading direction at an angle to fiber axis) were analyzed with the... 

The surface characteristics of materials dominate the performance of the final products in many applications. For instance the mechanical behavior of composite materials are strongly dependent on the nature of the fiber/matrix interface, the lubricant properties are influenced by surface tribological effects, the success of bio-implants is mostly determined by biocompatibility, etc. 

C.A. Correa, C.A. Razzino, and E. Hage. DMTA analysis of interface adhesion in wood-plastic composites. In Eighth International Conference on Woodflber-Plastic Composites (and Other Natural Fibers), Madison, WI, 2005. 

Three parts are covered in the chapter. First, the synthesis and properties of PLA are described. The modification and process of PLA are also discussed. Then, the composites with PLA as matrix and natural fiber or nanoparticles as reinforcement are reported in the second part. The processing and the properties of the composites are also given. The interface between PLA and the reinforcement and the surface treatment methods are discussed. Finally, the application and the development of PLA and PLA-based composites in the future are proposed. 

The production of composites from epoxy resins and fibres has significantly increased in recent time. Both the fiber and polymeric phases retain their original chemical and physical identities, with mechanical properties sometimes exceeding those of the constituents. The nature of the interface of the two phases is of enormous importance, particularly where high resistance to failure is sought [21]. 

In this section, major aspects of the mechanical behavior of fiber-reitiforced composites (based on both short and continuous fibers) are briefly considered. Since, as with particulate composites, the nature of the interfacial adhesion is important in determining modulus, strength, and toughness, the role of the fiber-matrix interface is also discussed. 

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