Surface modification alkali treatment

The pervaporation of water/acetic acid mixmres was also evaluated with ZSM-5 membranes by the Matsukata group [129] the initial values of the separation factors in a 50 wt% acetic acid aqueous solution were around 10 to 20 due to the preferential adsorption of acetic acid which decreased the amount of water adsorbed. To increase the amount of water adsorbed, a surface modification that consisted of an alkali treatment with NaOH was carried out. After the treatment, the water flux and separation factor increased markedly, reaching values up to 381 and 0.783 kg/m h, respectively. 

The work carried out by Kalaprasad and Thomas [34] shows different chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane, and peroxides improving the interfacial adhesion and compatibility between the fiber and matrix. A polyethylene thermoplastic matrix with sisal and glass hybrid composites was developed. The results showed that in all treatments, tensile strength increased about 10-30% and peroxide treatment showed maximum tensile strength and Young s modulus [34]. 

Morrison WH, Archibald DD, Sharma HSS et al (2000) Chemical and physical characterization of water- and dew-retted flax fibers. Ind Crops Prod 12 39-46 Mishra S, Misra M, Tripathy SS et al (2002) The infiuence of chemical surface modification on the performance of sisal- polyester bio composite. Polym Compos 23(2) 164-170 Bisanda ETN (2000) The effect of alkali treatment on the adhesitm characteristics of sisal fibers. Appl Compos Mater 7 331-339... 

Out of the above mentioned methods, alkali treatment process (mercerization) has been adopted for the surface modification of Sisal Fiber (SF). The treatment of the fiber was carried out by immersing the fibers in IN sodium hydroxide (NaOH) solution for 1 hour at room temperature. Then, these fibers were washed with distilled water containing few drops of acetic add, followed by thorough washing imder continuous... 

The hydrophilicity of the polymer is increased by introducing theses carboxyl and hydroxyl groups, which can theoretically lead to better cell adhesion during seeding. Such as, Nam et al. [42] reported that the surface modification of PLGA and poly (D,Z,-lactic acid) in the NaOH solution could moderate the surface of the polymers and promote the adhesion of hepatocytes. Gao et al. [44] stated that the surface hydrolysis of PGA meshes in the NaOH solution could increase the attachment ability of vascular smooth muscle cells. However, strong alkali treatment is accompanied with extended bulk degradation of the polyester, and... 

For this reason, the polymer substrate treatment represents a very important step in the technology of metallic or ceramic coating on the polymer substrate. Therefore, noble metals and other low reactivity metals do not wet the untreated polymer surfaces, forming three-dimensional spherical clusters growing in a Volmer-Weber mode. Surface modification of the hydrophobic polymer surface onto a hydrophilic one can be achieved by wet (acid, alkali), dry (plasma), and radiation treatments (ultraviolet radiation and laser), without affecting the bulk properties. Consequently, application of different pretreatment methods represents an efficient way to improve wettability and thin metal adhesion. 

Hossain et al. [45] studied the effects of surface modification of jute libers and nanoclay on jute-Biopol green composites. Four subsequent chemical treatments including detergent washing, dewaxing, alkali treatment, and acetic acid treatment were performed to facilitate better bonding between the fiber and matrix. The scanning electron microscopy and Fourier transform infrared spectroscopy study confirmed improved fiber surfaces for better adhesion with matrix after final treatment. Enhanced thermal... 

Alkali treatment Mercerization or alkali treatment with strong alkali bases was developed as a method for cotton fibre modification by John Mercerin 1850 [55], It is a common method to produce high quality natural fibres, by removing the natural and artificial impurities from the fibre surface. The chemical treatment reduces the fibre diameter and thereby increases the aspect ratio [26]. Mercerization is usually performed applying aqueous solutions of sodium hydroxide (NaOH), at reaction times of 30 min up to 3 hr. 

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