Potential use, mechanical and thermal studies of sabai grass fibre

Abstract

Listen

Translate article

Low-cost panels, corrugated sheets, etc., require cheap fibres such as agroforest-based materials which could be used for making composites. Sabai grass, a main construction material for thatches, walls, roofs and ropes, is inexpensive and is grown in large quantities in Raigarh, Ambikapur, Hoshangabad, Narsinghpur and Jagdalpur in Madhya Pradesh, India [1, 2]. It is used where high strength is not required [3-10]. It can also be used as a filler material in plastics and in mud matrix [10] after suitable pretreatment to the surface. The chemical composition is listed in Table I (based on dry weight). Standard methods [7] were used for the above analysis reported in TAPPI (Technical Association Pulp and Paper Industry, USA). The chemical constituents such as cellulose, lignin and ash are different in different sabai grass samples. Understanding the structure, mechanical and thermal behaviour of this grass fibre will open up new avenues for the utilization of this grass fibre. Therefore, it is necessary to know its structure, mechanical and thermal behaviour. In this study the structure, cell length in the fibre and cell wall thickness were measured. The strength and thermal degradation were determined. Sabai grass was obtained from Madhya Pradesh, India. Fibre was obtained by beating leaves with a hammer and was separated by pulling apart. The structure of this fibre was determined by observing silver-coated longitudinal sections (LS) and fractured cross-sections by scanning electron microscopy (SEM; Jeo135 CF). Samples for tensile testing were prepared by cutting a window of 5 cm in cardboard and fixing the fibre across it. An average of 20 ultimate tensile stress (UTS) values were taken as determined on a 1185 model Instron. Samples for thermal studies were prepared by chopping the fibres to a length of 1-2 mm. Thermogravimetric (TG) and differential thermogravimetric (DTG) runs were carried out on a Stanton model 730/750 thermal analyser in the temperature range 0-520 °C at a heating rate of 20 °Cmin -t in static air. Differential scanning calorimetry (DSC) runs were carried out on a Perkin-Elmer DSC-2C using aluminium pans in the temperature range 50-500 °C at a heating rate of 20 °Cmin -1. An inert atmosphere was maintained by flowing dry argon gas. The sample weight for all runs was about 5 rag. Fig. 1 shows sabai grass which is used for making rope and paper. Fig. 2 shows a longitudinal section having a large number of cells. The cell size varies from 3 to 20/zm. The cell width is 1.6-3.2/zm and the length 30-50/zm. Fig. 3 shows the stress-strain curve of sabai grass fibre tested at a crosshead speed of 0.005 mmin -1 . The UTS of sabai grass is 76 MPa. Fig. 4 shows cells fractured at a speed of testing of 0.005 m rain -a . Plant fibres of different age, source and place have different chemical compositions and hence different properties. Factors that mainly contribute to the tensile strength of a plant fibre are the cellulosic content and the microfibril angle of the fibre with cells arranged regularly bonded to each other by lignin. This type of structure can be assumed to be parallel to the fringed fibril structure, while crystalline regions (long imperfect crystals about 100 molecules in cross-section) are embedded in non-crystalline regions.