Physical properties of the natural fibers are crucial in determining their suitability for different industrial applications as well as natural fiber composites. Fiber’s length, diameter, and density as well as aspect ratio, thermal conductivity, cost, and availabil­ity are considered as key criteria and properties that can determine the potential usage of any natural fiber type in different industrial applications (Al-Oqla and Sapuan 2014; Al-Khanbashi et al. 2005; Alves et al. 2010). Date palm fiber can be considered as one of the most available natural type comparing to other natural fiber used in polymer composites for automotive industry. It can be estimated that the annual world produc­tion of the date palm fiber is about 42 times more than that of coir and about 20 and 10 times more than hemp and sisal production respectively. On the other hand, the fiber density is one of the most important physical properties that contribute implementing natural fibers in different applications. That is, it can lead to lower weight composites suitable for automotive and space applications. A comparison between the date palm fibers with other natural types regarding the density property is demonstrated in Fig. 1.8. It is noticed that date palm fiber have a lower density as compared to other natural fibers which give it an added value in the field of natural fiber composites.

On the other, hand, several researches had reported the significance of the aspect ratio (length/diameter) on the properties of final composite materials. Studies had investigated and proved that this aspect ratio of the date palm fiber has an intermedi­ate value regarding other natural fiber types which can attribute its usage in different industrial applications (Al-Oqla and Sapuan 2014). Table 1.3 provides useful physi­cal properties of the date palm fibers with other natural types. The physical proper­ties such as length, diameter, density, and micro-fibril angle of the date palm fibers made it potential for wide range of applications (Al-Oqla and Sapuan 2014; Faruk et al. 2012; Sbiai et al. 2010).