Adhesion natural fibers

Plant based natural fibers are lignocellulosic, consisting of cellulose micro fibrils in an amorphous matrix of lignin and hemicellulose. To improve the incorporation of natural fibers into polymers and to have higher fiber/matrix interfacial adhesion, natural fibers can be altered by different physical and chemical treatments. 

The quality of the fiber matrix interface is significant for the application of natural fibers as reinforcement fibers for plastics. Physical and chemical methods can be used to optimize this interface. These modification methods are of different efficiency for the adhesion between matrix and fiber. 

The mechanical properties of composites are mainly influenced by the adhesion between matrix and fibers of the composite. As it is known from glass fibers, the adhesion properties could be changed by pretreatments of fibers. So special process, chemical and physical modification methods were developed. Moisture repel-lency, resistance to environmental effects, and, not at least, the mechanical properties are improved by these treatments. Various applications for natural fibers as reinforcement in plastics are encouraged. 

Another major drawback of polysaccharides is their hydrophilic nature leading to low degrees of adhesion between fiber and matrix [11]. Moisture absorption takes place by three types of mechanisms namely diffusion, capillarity, and transport via micro cracks [2]. Among the three, diffusion is considered to be the major mechanism. Water absorption largely depends on the water-soluble or hygroscopic components embedded in the matrix, which acts as a semipermeable membrane. While, fiber/matrix adhesion and fiber architecture also affect the moisture absorption. The results of the water sorption experiment showed an interesting trend. The extent of water uptake was not very significant and also did not increase linearly with amount of filler (Table-2). 

The synthesis of PU can be carried out by the reaction described in Eq. (2.24). If the functionality of the hydroxy-containing compounds or the isocyanate is increased beyond 2, branched and possibly crosslinked polymers are produced. Because the nature of the polyol (polyether, polyester, polybutadiene, etc.) and isocyanate components can vary widely, PU are among the most versatile polymers, producing a wide variety of materials such as elastomers, foams, coatings, adhesives, or fibers. 

Wall-to-wall carpets may feel clean, but in reality they re anything but. Usually made of synthetic materials that off-gas, a lot of time they re covered in chemical stain-resistants and backed with chemical adhesives to help bind them together. Most also require glue to adhere them to the floor, which contains VOCs. Whenever possible, we recommend a natural wood floor with a natural fiber throw carpet or rug that can be either tossed in the washing machine or cleaned with a nontoxic carpet shampoo. 

Antioxidant used for wood or other natural fiber filled polyolefins, elastomers and hot melt adhesives when light exposure and maintenance of color is important. 

Epoxy resin adhesives for aluminum, glass, and steel have been prepared by converting octaallyl or octacrotyl-sucrose to the corresponding epoxides which were cured with diethylenetriamine.157 Several plastics, resins, and adhesives have been based on soybean oil.158 Vinyl esters of the fatty acids can be used as monomers. The oil can be epoxidized, then hydrolyzed to glycols, which can be converted to acrylates or maleates for polymerization. Natural fibers, such as hemp, can be used with such materials to form inexpensive composites. 

C.A. Correa, C.A. Razzino, and E. Hage. DMTA analysis of interface adhesion in wood-plastic composites. In Eighth International Conference on Woodflber-Plastic Composites (and Other Natural Fibers), Madison, WI, 2005. 

Some of the other materials used by early human beings as adhesives are now called beeswax, rosin, rubber, shellac, sulfur, tar, and vegetable gums. Later, as people developed bows and arrows, it was found that feathers fastened to an arrow shaft helped to stabilize the arrow s flight. The same sticky or heat-softened materials soon supplemented the use of natural fibers to attach the feathers. 

This is one of the most important natural fibers. It is produced in India, Bangladesh, Thailand, Vietnam, and other countries. It contains 56-64 wt% cellulose, 29-25% hemicellulose, 11-14% lignin, and a small proportion of fats, pectin, ash, and waxes. Application of jute fiber in RPs with matrices of TS resins such as unsaturated polyester or vinyl ester resins has been widely studied. To date the poor adhesion to hydrophobic TPs, such as polyethylene and polypropylene, has to date limited application in TPs. 

Improved fiber matrbc adhesion and thereby improved mechanical properties can be accomplished by engineering a superior processing condition in preparing the bio-composites, by altering the polymer architecture of the matrix or by the surface treatment on the fiber [47]. Table 23.1 showed mechanical properties of natural fiber-reinforced PLA composites. 

PEG/Cellulose Nanowhiskers (CNW) -The adhesion of PEG to the natural fibers can explain the lubricating effect of PEG in the preparation of composites with PHB and natural fibers. [39]... 

The interfacial bonding between fiber and matrix must be optimized since it is very important for effective stress transfer. Since the fibers and matrices are chemically different, strong adhesion at the interface is required while using natural fibers as reinforcement [37], One method is to improve compatibiUzation and... 

Uses Intemiediate for acrylic latexes and S/B latexes for paper coatings, carpetbackings, nonwoven textiles, adhesives, and paints reactive comonomer for acrylic, S/B, PVAc, nitrile latexes prep, of acrylic fibers copolymerization of nylon (caprolactam base), resins, plasticizers, interm iates, paper additives aluminum anodizing reagent lube oil additive in food-contact paper/paperboard in food-pkg. adhesives natural food acid (Japan) in cellophane for food pkg. 

Incompatibility between typically hydrophilic natural fibers and hydrophobic polymer matrices resulting in poor interfacial adhesion between the phases... 

Fitzer and co-workers [103] showed that the concentration of reactive fiber surface groups on HM fiber is about one magnitude less than for HT fiber, whilst wetting measurements and nitrogen determinations showed that the adhesion between fiber and matrix is at least 50% chemical in nature. The BET surface area of oxidized HT fiber was about forty times that of HM fiber, suggesting that physical adhesion or mechanical interlocking was not a contributory factor. 

Adhesion between fiber and matrix can be altered by surface treating the fiber [16,17], Surface treatments of carbon fibers have been developed for epoxy systems, but the optimum surface treatment for epoxy systems may be inadequate for newer resin systems. It may also be possible that by tailoring the interface between fiber and matrix, the mechanical properties of the composite can be controlled. To tailor the interface, it is necessary to understand the nature of carbon fiber surfaces and their reactions when surface treated. 

Mimker M, Holtman R, Michaeli W (1998) Improvement of the fiber/matrix-adhesion of natural fiber reinforced polymers. In Proceedings of 43rd iniranational SAMPE symposium, 31 May-4 June 1998, pp 2123-2133... 

Reinforcing fibers can be modified by physical and chemical methods. Chemical and physical modifications of natural fibers are usually performed to correct the deficiencies (described above) of these materials, especially to impart bonding and adhesion, dimensional stability, and thermoplasticity. Surface modification of natural fibers can be used to optimize properties of the interface. 

Franco PJH, Valadez-Gonzalez A (2005) Fibta-matiix adhesion in natural fiber composites. In Mohanty AK, Misra M, Drzal L (eds) Natural fibers, biopolymers and biocomposites. CRC, Boca Raton... 

Still another micromechanical method for single fiber simulation of a polymer composite interfacial adhesion is the microbond test. This method was developed by Miller et al. [52] and initially applied for S3mthetic fibers. As mentioned by Craven et al. [53], the microbond test is suitable for any fiber that can carry only low loads. This is the particular case of silk, a strong natural fiber but with limited load bearing capacity due to diameters that can be finer than 50 pm. This could be the case of some lignocellulosic fibers such as the ramie with diameters of the order of 10 pm. 

---