Civil Engineering Reference
In-Depth Information
h us production of nano/microscale cellulose i bers and their application in com-
posite materials has gained increasing attention in the past few decades. Some of the
basic advantages of the development of micro/nanocellulose-reinforced composite
material are: these i bers are mainly based on cellulose, which is the most abundant
material on our planet, and are low cost, easily available and renewable. Micro/nano-
i bers overcome certain drawbacks associated with natural i bers such as high aspect
ratio, low dimensional stability in moist environment, high porosity, etc. h e draw-
backs of natural i bers are based on their chemical composition and structure. Natural
i bers are about 10 times larger than that of synthetic i bers resulting in increased aspect
ratio in short-i ber-reinforced composites and thus decrease the load-bearing capabil-
ity. Natural i bers have a moisture absorption tendency which results in swelling of
the i bers. h ey have high degree of porosity due to the empty lumens of the ultimate
cells which account for the moisture absorption by capillary action. h e waxy materials
present on the i ber surface help to retain the water molecules on the i ber. Plant-based
natural i bers like sisal, jute, bamboo, wood and paper in their natural condition, as
well as several waste cellulose products such as shell l our, wood l our, and pulp, are
well established as i llers in polymeric matrices. h e conversion of these resources into
micro/nanosize needs systematic investigation. Scientists have been successful in the
extraction of these i bers from many natural resources. h e preparation of cellulose
nano/microi bers from natural i bers such as coir i ber [28] , banana i ber [29] , bagasse
[30], wheat straw [31], jute [32], hemp [33] and soybean [34] have been studied.
10.2
h
e Role of Isolation Methods on Composite Properties
In the recent past, the micro/nanoi bril-reinforced composites have been evaluated for
dif erent applications. A composite's properties are influenced by a number of vari-
ables, including the i ber type, environmental conditions, processing methods, and any
modification of the fibers. Generally a small weight percentage of nanoi llers results in a
large improvement in the properties of composites. h ey exhibit outstanding properties
compared to the conventional composites. h ough the cellulosic nanocomposites have
many advantages, the main drawback lies in the processing of these composites. Because
of inferior processing, the composites lack the desired or expected properties such as
mechanical behavior, thermal properties, etc. h e dispersion of these polar nanocellu-
losic components in polymer matrixes of ers a huge challenge, especially in non-polar
matrix. Besides, it is dii cult to predict the properties of nanocomposites since most of
the conventional models are not applicable in the case of cellulose nanocomposites. h e
amount of interface in nanocomposites greatly exceeds the amount in a conventional
composite with the same content but having larger phases. Proper tuning of the inter-
face can enhance the properties of composite exhibiting unique properties [35]. h ough
the extraction of cellulose micro/nanoi bers from natural resources has been well stud-
ied, the availability of these i bers in the proper format for the composite industry is a
huge challenge. h is is mainly due to their polar and hydrophilic nature, which results
in low compatibility with polymer. Also, the aggregation of extracted i bers is a factor
of major concern. Dif erent methodologies have been adopted by researchers to over-
come these issues. Proper extraction to obtain stable micro/nanoi bers, their surface
