Civil Engineering Reference
In-Depth Information
Based on this consideration, kenaf has potential as raw material to produce cellulose
nanoi bers [2] or whiskers.
Cellulose whiskers could be dei ned as the formation of high-purity single crystals
of nanoi bers which have been grown under controlled conditions [3]. h e morphol-
ogy, such as size, shape and dimension, of whiskers dif ers according to the nature of its
sources and hydrolysis conditions [3-4]. h e diameter of whiskers ranges from 5 to 10
nm, while the length ranges from 100 to 500 nm [5]. Whiskers contain a small number
of defects since they are devoid of chain folding. h erefore, whiskers application in
composite reinforcement is promising.
Cellulose acetate butyrate (CAB) is a group of cellulose esters. h ese polymers are
produced from renewable materials sources. Acting as thermoplastic polymers proper-
ties when CAB, which is highly-purii ed cellulose, has been plasticized [6]. CAB was
introduced as a tougher versions of CA. It exhibits inelasticity properties and tendency
to creep under load because of the rigid rod nature of the cellulose backbone [7]. h e
higher butyryl content of CAB, l exibility, solubility, hydrocarbon tolerance, and com-
patibility will increase. Otherwise, chemical resistance, grease resistance, and hard-
ness decrease [7]. Moreover, the higher molecular weight, compatibility and solubility
decrease, toughness and melting point increase, and hardness and density are unaf-
fected [7] .
Ayuk
et al.
used cellulose nanowhiskers (CNW) from microcrystalline cellulose
(MCC) as reinforcement in the CAB matrix [8]. h ey found an increasing of dynamic
mechanical and thermal stability properties, while the transparency decreased with
increasing CNW content. Siquera
et al.
used nanowhiskers and microi brillated cel-
lulose (MFC) from sisal to observe the inl uence of i ber loading on polycaprolactone
(PCL) [9]. Although a limited reinforcing ef ect was performed by sisal whiskers, the
glass transition, crystallization, melting temperatures and the degree of crystallinity of
the PCL matrix were increased.
Numerous studies have investigated the ef ect of cellulose whiskers on nanocompos-
ite. Based on our knowledge no information has been reported on CAB/Kenaf whiskers
nanocomposite properties. h erefore, the main objective of this work was to character-
ize the properties of kenaf whiskers/CAB nanocomposite. h e inl uence of dif erent
whiskers loading percentages on chemical, thermal and dynamic mechanical proper-
ties wereinvestigated.
13.2
Experimental
13.2.1
Materials
Four-month old kenaf stems of variety 36 were obtained from the experimental plot
of the National Kenaf and Tobacco (NKTB) Company, Malaysia. h e harvested kenaf
stems were peeled to separate the outer part (bast) from the inner part (core). h e bast
was then dried in an industrial oven to a moisture content of 9.8%. Acetone was sup-
plied by Mallinckrodt. Sulfuric acid (95%), chloroform, and CAB were purchased from
Aldrich, while sodium chlorite and sodium hydroxide were supplied by RND I-Tech
Sdn., Malaysia. CAB had a number average molecular weight of 70,000, a density of
