Materials have critical roles in engineering design and applications that can lead to successful sustainable products. The proper compatibility between the material and products’ functions, performance, and recyclability became critical for engineering applications. Moreover, finding new materials with desirable distinctive characteristics can expand new design possibilities (Ashby 1992). On the other hand, several criteria and limitations usually affect the usage of a specific type of material in a particular application (Ashby 1992). Thus, selecting a proper material type for a particular appli­cation is a matter of multi-criteria decision making problem (Dweiri and Al-Oqla

2006) where proper decisions have to be carried out based upon several factors.

Recently, due to the tremendous need and awareness of environmental impact and as a result of the governmental emphasizing on the new regulations regarding the environmental impact issues and sustainability concepts as well as the growing of social, economic, and ecological awareness (Faruk et al. 2012; Kalia et al. 2011a, b), the utilization of natural resources was strongly encouraged (Govindan et al. 2014). Consequently, the natural fiber reinforced polymer composites (NFRPC), (simply NFC), became a valuable alternative material type for wide range of applications. In this NFC, natural fibers (such as jute, hemp, sisal, oil palm, kenaf, and flax) are utilized to be fillers or reinforcing material for polymer-based matrices. Such utili­zation of natural fibers can decrease the amount of waste disposal problems, and enhance reducing in environmental pollution (Kalia et al. 2011b). Such materials are attractive from environmental point of view where they can be used as an alter­native to the traditional glass/carbon polymer composites (Faruk et al. 2012; Kalia et al. 2011a, b). They can be used in different applications such as packaging, dis­posable accessories, furniture, building, insulation, and automotive industries (Al-Oqla and Sapuan 2014). Moreover, these NFC have several advantages over the traditional types of materials like the low costs and density as well as acceptable specific strength and modulus (Alves et al. 2010 ; Faruk et al. 2012; Kalia et al. 2011b) which can lead to low weight products.

Furthermore, natural fiber composites are acceptable from environmental points of view because they can participate in producing recyclable and biodegradable products after use (Alves et al. 2010; Kalia et al. 2011a; Mir et al. 2010). Comparable to synthetic fiber composites, NFC are much cheaper, good thermal as well as acous­tic insulating properties that can widen their industrial applications (Alves et al. 2010; Faruk et al. 2012). On the other hand, natural fibers have several advantages over the traditional glass fibers such as: availability, CO2 sequestration enhanced energy recovery, reduced tool wear in machining, and reduced dermal and respira­tory irritation (Al-Oqla and Sapuan 2014 ; Faruk et al. 2012 ; Kalia et al. 2011b; Sarikanat 2010). Despite of that, natural fibers have some considerable drawback demonstrated in poor water resistance, poor bonding with the matrix, and low dura­bility, The weak interfacial bonding between natural fibers and the polymer matrix can lead to undesirable properties of the composites a

and bonding. Consequently, the usage of the coupling agents and surface treatments via mechanical, chemical, and/or physical modifications was implemented (Al-Khanbashi et al. 2005; Arbelaiz et al. 2005; Faruk et al. 2012). A general clas­sification of the natural fibers can be classified based upon their origin as bast fibers, leaf fibers, fruit, and seed-hair fibers as seen in Fig. 1.1. Wide different natural fiber types had been used to reinforce different polymer matrices. Such fibers include wood, cotton, bagasse, rice straw, rice husk, wheat straw, flax, hemp, pineapple leaf, coir, oil palm, date palm, doum fruit, ramie, curaua, jowar, kenaf, bamboo, rapeseed waste, sisal, and jute (Jawaid and Abdul Khalil 2011; Majeed et al. 2013). A sche­matic diagram of the general classifications of natural fibers is shown in Fig. 1.1.