Extraction and surface characterization of novel bast fibers extracted from the Pennisetum Purpureum plant for composite application

Abstract

Pennisetum Purpureum, known as Napier grass, belongs to the Poaceae family. It has been introduced as forage into most tropical and subtropical regions worldwide. This grass originated from sub-Saharan tropical Africa. Napier grass was first introduced into Malaysia in the 1920s and is currently the most popular fodder grass in dairy and feedlot production systems. The worldwide acceptance of natural fiber usage has resulted in many varieties of potential fiber being explored for embedding in many applications. The main objective of this investigation was focused on the extraction of fiber from the Napier grass plant. Its characterization, in terms of its physical and chemical properties, has been recorded. Thermal degradation testing, surface chemistry analysis and a determination of the functionality of the treated fibers have been performed. The water retting method is used to extract the bast fibers. Several different concentrations of the chemical of sodium hydroxide (NaoH) (5%, 10%, 15% and untreated) have been used for the treatment. Characterization of this fiber strand is determined by its physical character after treatment, and its chemical composition content has been determined in terms of cellulose, hemicellulose, lignin and moisture. Using Thermogravimetric Analysis by thermal degradation (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) spectra, assessments have been made of the untreated and NaoH-treated fiber strand. Higher concentration use, i.e. 15% NaoH treatment, gives a better sizing for the fiber’s strand yield diameter (1.49mm). The chemical composition of the fiber was recorded, as 15% treatment resulted chemical composition content (cellulose is 54.26%, hemicellulose is 18.85%, lignin is 25.33% and the water percentage is 5.93%). TGA indicates that the thermal stability of the treated fibers increased due to the removal of hemicellulose on NaOH treatment. Thermal stability occurs in the ranges of 120-330°C and 290-330°C for untreated and NaOH-treated fiber strands respectively. These results show that treated fibers can be used as reinforcement even with thermoplastic polymers where the processing temperature is above 300°C. FTIR studies suggest a reduction of the hemicellulose and lignin content on NaOH treatment of the fibers. This strongly supports the chemical analysis data; treated fiber content removal of unwanted cells gives a better surface to the fiber. In conclusion, the surface of the fiber strand is enhanced by treatment, which gives better mechanical interlocking between the matrix and the fiber in a composite’s structure