Home | About Jute | Jute Prices | Organisation | Directory | Technology | Statistics | Diversification | Jute Policy | Jute News | FAQ

  Jute Reinforced Composite  Technology               

Effect of Moisture on Jute Fibres
There is, however, a major drawback associated with the application of jute fibres for reinforcement of resin matrices. Due to presence of hydroxy and other polar groups in various constituents of jute fibre, the moisture uptake is high (approx. 12.5% at 65% relative humidity & 20o C) by dry fibre[5].  All this leads to (i) poor wettability with resin and (ii) weak interfacial bonding between jute fibre and the relatively more hydrophobic matrices. Environmental performance of such composites is generally poor due to delimitation under humid conditions. 

With increase in relative humidity up to 70%, the tenacity and Young’s modulus of jute increases but beyond 70%, a decrease is observed. Thus, it is essential to pre-treat the jute fibre so that its moisture absorption is reduced and the wet ability by the resin is improved.

Modification of Jute Fibre 
In order to develop composites with better mechanical properties and environmental performance, it is necessary to impart hydrophobicity 
to the fibres by chemical reaction with suitable coupling agents or by coating with appropriate resins. Such surface modification of jute fibre would not only decrease moisture adsorption, but would also concomitantly increase wet ability of fibres with resin and improve the interfacial bond strength, which are critical factors for obtaining better mechanical properties of composites. Modification of jute and other natural cellulose fibres can be done by following means :

Food Grade Jute Bags

Chemical means 
    Coating with polymeric solutions and  Graft copolymerisation. 
Jute is chemically treated with isopropyl triisostearoyl titanate 
(abbreviated as titanate), g - aminopropyl trimethoxy silane 
(abbreviated as silane), sebacoyl chloride (SC), and toluene 
diisocynate (TDI).

All these reagents are expected to block the hydroxy groups of jute thus making the fibres more hydrophobic. These surface modifiers penetrate and deposit into lumens of cell wall of fibre, minimising the possible extent of moisture ingress.  Polymeric coating of jute fibre with phenol-formaldehyde or resorcinol formaldehyde resins by different approaches are highly effective in enhancing the reinforcing character of jute fibre, giving as high as 20-40% improvements in flexural strength and 40-60% improvements in flexural modulus. These modifications improve the fibre-matrix resin wettability and lead to improved bonding [6,7].  Jute can be graft copolymerised with vinyl monomers such as methyl methacrylate, ethyl acrylate, styrene, vinyl acetate, acrylonitrile and acrylamide in the presence of different redox initiator systems such as vanadium - cyclohexanol, vanadium - cyclohexanone, etc.

Grafting of polyacrylonitrile (10-25%) imparts 10-30% improvements in flexural strength and flexural modulus of the composites. Grafting of polymethylmethacrylate is also effective in this respect, though to a lower degree. 

Jute-Polyester Composite
Polyester resin forms an intimate bond with jute fibres upto a maximum fibre: resin ratio (volume/volume) of 60:40. At this volume fraction, the Young’s modulus of the composite is approximately 35 GN/m2. For higher volume fraction of fibre, the quantity of resin is insufficient to wet fibres completely [8].

In order to overcome the poor adhesion between resin matrix and jute 
fibres, a multifunctional resin like polyesteramide polyol has reportedly been used as an interfacial agent. Significant improvement in mechanical properties of jute fibre composites was observed by incorporation of polyesteramide polyol. Also, hybrid composites of glass at surface and treated jute fibre at inner core can be a good alternative [9,10].

There are several types of unsaturated polyester resin - general purpose, flexible, resilient, low-shrinkage (low profile), weather resistant, chemical resistant and fire resistant varieties. These polyester resins are prepared from a blend of phthalic anhydride and maleic anhydride esterified with propylene glycol to form linear polyester chains having molecular weights in the range 1000-3000.  For Curing of such unsaturated polyester resin with fibre, azo type initiators (R-N=N-R) and organic peroxides (R-O-O-R) are generally used.