Jute cultivated in the tropics and subtropics. The plants

Jute (Corchorus) is one of the most
important lignocellulosic fibrous crop belonging to the Tiliaceae family,
mostly cultivated in the tropics and subtropics. The plants are generally
annual herbs, and mature plants, grows 2.5-4 m in height and a basal diameter
of about 25 mm (Ghosh et al.2013; Kumar et al. 2014; Del Rio 2009 ). The fibers are developed in the
bark region of the stem. The fibres are held together by pectinous gummy
material which keeps the fibre bundles stick with non-fibrous tissues of jute
bark. Jute fibers are 1 to 3.5 m long can be extracted from the bark of the
stem after retting process. Jute fibre is multi cellular structure composed of
variable number of cells cemented tightly by intercellular substances.  The jute cells are composite structure, long cellulosic fibrils embedded in a
matrix of hemicelluloses and lignin to form ultimate jute cell. The physical
properties of lignocellulosic fibre are dependent on the three basic components
cellulose, hemi-cellulose and lignin (Saha et
al. 2010; Gowda et al.1999; Das 2015a; Das 2017a ). Cellulose is the major component of jute
fibre, long cellulosic fibrils embedded in a matrix of hemicelluloses
and lignin and form ultimate jute cell. Jute cell is cemented together by
lignin to form a long filament (Joshi 2004; Mukheijee 1993; Das 2016). The cellulose fibrils are the main
tensile strength provider of jute fibers. The major portion of the cellulose is
micro-crystalline structure with high order of crystalline regions. The
mechanical properties of cellulosic fibres are mainly governed by cellulose
content and the spiral angle of the fibrils. Generally, fibres stiffness
increases with higher
cellulose content and lower microfibril angle of
cellulose chains. Other components of the jute fibre are hemi-cellulose, lignin
and pectin also increase fiber stiffness, they transfer load to cellulose
chains. Tensile strength and modulus of fibers is an important parameter for
their selection of uses (Bledzki, & Gassan,
1999; Mwaikambo 2009). Jute fibre
possess some advantageous physical properties, like high tensile strength, low
tensile elongation at break, low cost and eco-friendly fibres which are
renewable makes it attractive for use as reinforcing material (Jawaid 2013; Das 2017b). 

Being natural hydrophilic
cellulosic fibre, jute has some drawbacks such as high moisture absorption, poor dimensional stability, the
relatively poor thermal stability,  poor
compatibility towards a hydrophobic polymer matrix, resulting in weak
interfaces and poor mechanical properties of the composites (Doan & Brodowsky, 2012; Akil 2009; Sever et al. 2012;
Das & Bhowmick 2015b ).

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Several researchers have researched
on the physical and mechanical properties and improvement of mechanical and
interfacial properties of jute fibre composites.  (Roe and Ansel 1985)  They
prepared the unidirectional jute composite in polyester resin matrix by the
press-molding technique. The fibre strength and modulus were reported 442 MPa
and 55.5 Gpa, respectively. They reported that polyester resin formed an
intimate bond with the jute fibres up to a volume fraction of 0.6, above which
the quantity of resin was insufficient to wet out the fibres completely. Then
tensile strength and modulus of jute composite at volume fraction of 0.6 were
250 MPa, 35 GPa respectively.   Dash et al. prepared an economical
jute-polyester composite by using solution impregnation and hot curing methods.
They fabricated composites by using both untreated and bleached jute slivers in
polyester resin matrix with different percentages of fibre loading. It was
observed that tensile and flexural properties of 60 wt% fibre loading composites
yielded the best results (Dash
et al. 1999). Gassan and Bledzki reported that the treatment of the
isometric jute yarns with 25% NaOH for 20 min resulted in an improvement of
120% and 150% in the tensile strength and modulus of the jute yarn. They
reported a 60% improvement in the jute-epoxy composite’s tensile properties,
reinforced with these treated yarns (Gassan and Bledzki 1999b).

 

To the best of our knowledge, no
research work has been reported in the literature on lengthwise jute fibre
properties variation and its effect on mechanical properties of composite. In
this study, physicochemical properties variation of three portions of jute
equally cut from root to tip of a jute reed is studied. The three portions jute
fibre was used to fabricate unidirectional composites in polyester resin
matrix. The tensile and flexural properties of these composites have been
compared and reported. The primary objective of this work is to lengthwise
fibre properties variation and its effect on mechanical properties of
composite.