## 2 Banana Fibers
### Mechanical Properties
Examples of used SCT are:  
* Alkalization or mercerization (using sodium hydroxide (NaOH)) [77; 85; 134];* Silanization by using silanes (e.g., 3-aminopropyltriethoxysilane (APS), bis-(3-triethoxy silyl propyl) tetrasulfane (Si69), methacryloxymethyl trimethoxy silane, and vinyl triethoxy silane) [32; 34,48; 77; 93; 94; 103; 135];
* Potassium permanganate (KMnO\({}_{4}\)) treatment oracylation [77; 136], potassium metabisulfite (K\({}_{2}\)S\({}_{2}\)O\({}_{5}\)) [6], potassium hydroxide (KOH) [6], sodium lauryl, sodium hypochlorite (NaClO), sodium chlorite (NaClO\({}_{2}\)) [6], and acetic acid (CH3 COOH) [6; 32; 34; 48; 93; 103];
* Oxalic acid (C\({}_{2}\)H\({}_{2}\)O\({}_{4}\)) acetylation, methylation, cyanoethylation, benzoylation (with benzoyl chloride) [15; 19; 77; 137];
* Acrylation and the direct removal of amorphous materials/adsorbed components (which makes the NF incompatible with PM) such as lignin, fats, olefinic waxes, proteins, non-crystalline parts, and extractives by bleaching or steaming, etc. This step increases the decomposition temperature of treated NF due to the removal of amorphous and smaller molecules (and thus an increase in molecular weight) from the NF surface [19; 127; 138; 139]. In general, the alkalization and acetylation (with acrylic acid (C\({}_{3}\)H\({}_{4}\)O\({}_{2}\))) are the most effective and economical techniques for SCT [37; 38; 59; 85; 140]. The alkalization of the NF can be done according to ASTM D1965-87 standard [141]. The alkalization of the NF removes the noncellulosic and amorphous components (e.g., hemicellulose, lignin, pectins, oil, waxes, and impurities from the wall surface of BF), the smelly odors, moistures, and weak structure. It also changes the color of the NF, the network structures of hydrogen bond due to the reaction with alkaline-based solution (NaOH), and the interfibrillar region of NF, which becomes less dense, less rigid, less hydrophilic, and rougher. As a result, the adhesion of the NF to PM and the surface wettability are improved, which consequently improves the mechanical interlocking/behavior (e.g., tensile and yield strength) into the IR [3; 48; 85]. The acetylation of the natural fibers reduces their tensile strength and hygroscopicity when compared with alkaline surface chemical treatments. This is due to the loss of hemicelluloses from the NF surface and also due to the generation of an ester bond when the carboxylic group of the C\({}_{3}\)H\({}_{4}\)O\({}_{2}\) reacts with the cellulosic hydroxyl group of the NF, respectively [37; 48; 142]. An indirect method to treat the NF is the addition of a compatibilizer into the PM. Compatibilizers are generally graft, block copolymers, or graft copolymers (GC) obtained by the modification of PM. The graft can be done by monomers such as stearic acid (C\({}_{18}\)H\({}_{36}\)O\({}_{2}\)), acetic anhydride (C\({}_{4}\)H\({}_{6}\)O\({}_{3}\)), maleic anhydride (MA), methylacrylate (MTA), acrylic monomers [37; 60; 143; 144], etc. The GC can be added into the PM with initiators, namely benzoyl peroxide (C\({}_{14}\)H\({}_{10}\)O\({}_{4}\)), dicumyl peroxide (C\({}_{18}\)H\({}_{22}\)O\({}_{2}\)) [12; 96; 97], etc. The use of compatibilizers not only treats the PM, but also the NF, and significantly improves the IR interfacial adhesion by the formation of covalent linkages between the anhydride and hydroxyl groups of the cellulose of the NF [37; 60; 145; 146]. Appendix A (Table A1) presents the various methods that have been used by some authors to extract, wash, and modify the BF before their incorporation into UPM or MPM.