Civil Engineering Reference
In-Depth Information
During the last two decades micro/nanocellulose-reinforced composites have been
the subject of intensive research and a number of review papers have appeared covering
this work [14, 17, 19, 24, 53, 173, 174]. Nanocellulose either in CNC or NFC form will
result in varying reinforcement of nanocomposites. Also, dif erent types of nanocel-
lulose can be used in various forms of reinforcement, including distributed reinforce-
ments, planar reinforcements, or continuous networked structures.
Beside the above advantages of nanocellulose as reinforcement in nanocomposites,
they present some disadvantages, for instance, high moisture absorption, poor wetabil-
ity, incompatibility with most polymeric matrices and limitation of processing temper-
ature. Indeed, lignocellulosic materials start to degrade near 220°C and this character
restricts the type of matrix which can be used with natural i llers [17] . To fully utilize
the potential of nanocellulose as reinforcement in composite materials, the hydrophilic
nature of cellulose should be altered to make it more compatible with organic solvents
and nonpolar polymer matrices. h is changing improves both the incorporation of cel-
lulose into the composite materials, which results in more homogeneous composites,
and the interfacial adhesion between nanocellulose and matrix in the i nal composite.
h is section focuses on thermoplastic and thermoset polymer nanocomposites
based on nanocelluse, their production processes, characterization and application.
11.7.1
h
ermoplastic Polymer-Nanocellulose Nanocomposites
Many thermoplastic polymers have been used as matrix with nanocellulose as rein-
forcement such as poly(vinyl alcohol) (PVA) [130, 175], polyurethane [176, 177],
polypyrrolle [178], polypropylene [179], poly(latic acid) (PLA) [180], hydroxypropyl-
cellulose (HPC) [74], polyacrylamide [181], etc. Figures 11.24 [182] and 11.25 [178] are
examples of thermoplastics reinforced by nanocellulose.
Poly(vinyl alcohol), which is one of the thermoplastic polymers, is a water solu-
ble synthetic polymer, has excellent i lm forming and emulsifying properties [183],
is interfacial, easy to process, has good physical and chemical properties [184] and is
inexpensive [185]. It also has high tensile strength and l exibility [130]. Because of these
interesting properties, PVA has been the subject of much research in this i eld. For
example, Cho and Park [183] investigated the mechanical and thermal properties of
PVA-based nanocomposites reinforced with CNC isolated from MCC. h ey cast nano-
cellulose suspension-PVA on a Tel on-coated petri dish. h eir results showed that the
tensile modulus decreased at 1 wt% CNC loading, and then increased with an increase
LDPE + modiied
Whiskers C18
90: 10
LDPE + Whiskers
90: 10
LDPE
Figure 11.24
Photographs of neat i lm and nanocomposite i lm (LDPE) based on ramie CNC [182].
