Studies On Basic Properties Of Palm Fiber

Palm fiber has been used for a long time in China, it was made into ropes, rain capes and mattresses in ancient time, while composite materials and elastic materials that belong to new areas nowadays. Palm is widely distributed in China, and palm fiber is abundant and picked off easily. However, researchers and manufactures have always paid much more attention to the utility instead of basic and deeper studies of palm fiber. From the researches of home and abroad, it can be concluded that there does not exist any systematic studies on rebound resilience, anticorrosion, morphological structure and chemical composition. This paper elaborates several achievements about palm fiber on the basis of properties studies.Pictures gained by optical microscope show that palm fiber has grooves with natural continuous but slight curves like S or Z in longitudinal surface, in addition, each fiber has only one type groove. Structure of fiber’s cross section, longitudinal section and surface is observed using SEM, also, figures reveal that palm fiber is so called vascular bundle and consists of hundreds of single fibers. The vascular bundle is not smooth with many holes as it covers by scale-like material. The cross section is near circular; also, the vessel closest to the center is bigger in diameter. Single fibers are all isolated with amount of interspaces. Each single fiber appears a hollow cavity, and there exists a piece of thin membrane owning wave-like wrinkles in inner wall like that of bamboo every other distance.The X-ray diffraction analysis shows that palm fiber is the typical cellulose I crystal with crystallinity of 37.92%. The chemical composition are qualitatively tested using infrared spectroscopy technique, then the result shows that palm fiber mainly consists of cellulose and lignin. Through quantitative analysis of chemical composition, the quantity of each component is obtained as follows:cerolipoid 3.77%, hydrotrope 2.80%, pectin 0.60%, semi-cellulose 20.60%, lignin 44.07% and cellulose 28.16%.Palm fiber is such kind of natural fiber with big, uneven diameter ranging from 199μm to 539μm, and mostly from 250μm to 400μm. The CV index of diameter is within 1.7%～18.1%, mainly 10%. Therefore, the square of cross section calculated from average diameter can be available, promising the reliability of follow-up calculation.The value range of rupture strength, Young modulus and rupture elongation gained after fracture tensile test is 89～222 MPa,0.44～1.09 GPa and 14.68～23.45%, respectively. That means palm fiber has medium strength and high elongation. The rupture strength (MPa) tends to decrease with the increase of diameter; the rupture elongation (%) increases a bit when the distance set in the test decreases.The rebound resilience appears to be excellent in research taken under circumstances of high load, stretching for a long time or being bending. The increase of work time and load do have bad effects on palm fiber’s rebound resilience, that is to say, the rebound resilience decreases. However, the rebound rate increases with longer recovery time.The rebound rate of palm fiber recovers very quickly in the first 5min of recovery time, then the recovery process slows down, because the recovery time influences the rebound rate a lot. Within 1h, the rebound rate can reach to above 50%, and bending slow elastic deformation recovers entirely in a very long time. The bending time has greater influence on bending rebound rate than load.Palm fiber’s rebound rate under constant load decreases in linearity mostly when the load increases, actually, the lowest rate can also reach to above 50%; however, the decreasing tendency of rebound rate is first gentle, then sharp with the lasting stretching time. Under the circumstance of different constant stretch values, the magnitudes of rebound rate decline after several stretching tests under the same frequency are much the same, so the recovery rate is separate with constant stretch value. Under the same constant stretch value, the rebound rate decreases gradually when the stretch frequency increases. Such decreasing tendency shows to be quicker at first, then slower. Along with the lasting of repeated stretch, the stretch frequency does not have strong influence on rebound rate any more.Hygroscopicity study indicates that palm fiber’s hygroscopicity is excellent, at the same time, the balanced moisture regain of moisture absorption and moisture releasability, and the moisture absorption hysteresis gap is respectively 16.65%,23.83%,7.2%, obviously, all of them are better than those of cotton fiber and flax fiber. The palm fiber’s moisture absorption processes more slowly than do that of flax and cotton fiber, but the former goes more quickly than do the latter two after about 10min. Among the three plant fibers, palm fiber has the biggest moisture releasability rate, then does flax fiber and cotton is the last one, but the former is slower than that of the both latter two after 35min to 40min. With time prolonging, the moisture absorption rate and moisture releasability rate of all the three kinds of fibers both slow down in exponential form.