Civil Engineering Reference
In-Depth Information
8
Cellulose-Based Liquid Crystalline Composite
Systems
J. P. Borges
1, *
, J. P. Canejo
1
, S. N. Fernandes
1
, P. Brogueira
2
, and M. H. Godinho
1
1
CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia,
FCT, Universidade Nova de Lisboa, Caparica, Portugal
2
Physics Department and ICEMS, Instituto Superior Técnico, ULisboa, Lisboa. Portugal
Abstract
Cellulose is the most abundant biopolymer on earth. It can be used in dif erent applications,
namely in the form of i bers, and cellulose can be converted into numerous cellulose deriva-
tives. Cellulose micro- and nanoi bers have been the subject of intense research in the i eld of
composites. Cellulose derivatives can show liquid crystalline chiral nematic phases, which can
be used for the production of diverse composite systems. All-cellulosic composites based on
liquid crystalline cellulosic matrices reinforced by cellulose micro- and nanoi bers can show
enhanced mechanical properties due to i ber orientation induced by the liquid crystalline
matrix. Cellulose-based i bers electrospun from liquid crystalline phases can develop dif erent
structures, which are able to mimic the shape of plant tendrils on the nano- and microscale,
opening new horizons for cellulosic membrane applications.
h e two systems mentioned above, concerning the production of cellulose composites from
liquid crystalline phases, will be surveyed in this chapter.
Keywords:
Liquid crystalline phases, cellulose-based polymer, nanocrystalline cellulose,
microcrystalline cellulose , composites , i lms , electrospun i bers
8.1
Introduction
Cellulose is the most abundant natural polymer and one of the most important renew-
able resources. Cellulose is the structural component of plant cell walls, and represents
one of the most important natural forms. Mankind has been using cellulose as a renew-
able raw material for millennia as a source of wood and i bers to apply in a wide range
of areas, from the production of tools to the manufacture of textiles. It was only in 1838
that Anselm Payen [1] determined the empirical formula of cellulose by isolating a
white powder from plant tissue previously treated with acid, or ammonia, followed by
treatment with water, alcohol or ether [2, 3]. In 1839 he coined the term cellulose for
