Navin Chand

Bibliography Resource structure properties of natural cellulosic fibres — an annotated bibliography

We present a review of the work on the structure and properties of some natural lignocellulosic fibres with a classified list of references on resource, structure, physico-mechanical properties and on the uses of these fibres. This list of references includes papers published in scientific journals and in the proceedings of conferences.

Mechanical properties of sisal fibre at elevated temperatures

Sisal fibres extracted from the leaves of Agava sisalana plants 3, 5, 7 and 9 years old were tested at different temperatures for tensile strength, elongation, toughness and modulus. The tensile strength, modulus and toughness values of sisal fibre decreased with increase in temperature. The effect of plant age on tensile strength, tensile modulus and toughness of sisal fibre became very much less at 100 °C as compared to 30 °C. Fractured fibres were observed by using a scanning electron microscope. The ends of fibres fractured at elevated temperature showed a failure similar to that of inorganic fibres. Elongation values at all temperatures increased with age. Elongated capillaries were observed in fibres fractured at 80 and 100 °C, due to the removal of moisture and volatiles originally present in the fibres. The fibrils are clearly observed in the form of hollow cylinders. Fractured surfaces are composed of brittle as well as ductile phases. The ductile portion increased with the increase of temperature.

SEM and strength characteristics of acetylated sisal fibre

Lacetylation du sisal cree des faisceaux de microfibrilles en certains endroits de la fibre, diminue denviron 30% la resistance a la traction et diminue de moitie sa teneur en humidite

Potential use, mechanical and thermal studies of sabai grass fibre

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.

Surface and Strength Properties of PVC-Sb2O3 Flame Retardant Coated Sunhemp Fiber

Sunhemp fiber was coated with different compositions of anti mony compounds (Sb2O3)—Polyvinyl chloride (PVC) fire retardant solutions. Changes in surfaces, breaking strength and in thermal stability of coated sunhemp fibers were determined. It was observed that the coatings changed the surface and ultimate tensile strength (UTS) of sunhemp fiber. The DSC peak occurred at lower temperatures in the case of coated fibers.

Structure and properties of Ipomoea carnea: Its performance in polymer, clay and cement based composites

Ipomoea carnea (Besharam) which grows wild in India has been identified as a useful material for several applications including housing. Problems associated with this material for housing are listed and a study of the structure, properties, mechanical and thermal behaviour has been conducted. Ipomoea carnea is a ligno-cellulosic plant material with a measured tensile strength of the order of 15–25 MN/m2 and a high flexure strength. These results are discussed in terms of the cellulose contents and spiral angles of ligno-cellulosic materials. The width of the cells in Ipomoea is of the order of 40–50 ωm with a wall thickness of the order of 10 ωm; the length of the cells in the central part can be of the order of 250 ωm. The powder of Ipomoea carnea is stable up to nearly 200°C, above which it shows signs of degradation. Ipomoea carnea chips, and its powder mix and bond readily with polyester resin, cement and mud. Coating of cresote, polyester, cashew-nut shell liquid and copper were successfully applied on the surface of Ipomoea carnea. The tensile strength of polyester containing 3.68% vol. Ipomoea carnea powder was of the order of 22 MN/m2. The bond strength of Ipomoea carnea with mud plaster + 2.5% cement was good. The ultimate load bearing capacity of 2.5% cement stabilised mud plastered panel having 14% vol. Ipomoea gave a factor of safety of 3 for normal wind loading, indicating that it is a promising material for housing.

Role of polymeric matrices in improving wear resistance of irradiated FRP composites

The present paper reports the effect of different resin matrices on the abrasive wear behaviour of woven fabric composites based on them. Three different resin systems and a common glass fibre reinforcement were used in the present study. It was found that polymer composites based on the epoxy resin system show maximum wear resistance. This has been attributed to the fact that fibre-matrix interfacial bonding is very strong between the glass fibres and epoxide resin. The bonding resists composite failure and improves on irradiation.

Low stress abrasion of laser irradiated GFRP composites: an experimental and microstructural study

The present paper reports, the mechanism of material removal during low stress abrasive wear of high weight percent glass fibre reinforced polymer (GFRP) composites. Two different geometries of glass fibre reinforcement namely woven roving (WR) and chopped strand mat (CSM) were used. Unsaturated isophthalic polyester and bisphenol based epoxy resins were used as matrix for the reinforcement. Rubber Wheel Abrasion Tester (RWAT) was used for evaluating the abrasive wear behaviour of the composites. The composite samples were irradiated using a low power He-Ne laser for different time periods, having intensity of 5 mW. The abrasive wear performance of the composites has been determined as a function of applied load, sliding distance and laser irradiation time. The microstructural features of the abraded surfaces of both the laser irradiated and unirradiated composites have been observed by using a scanning electron microscope. Unsaturated polyester based glass fibre woven roving (WR) composite had a higher wear volume as compared to the epoxy based composite. The trend reversed in the case of chopped strand mat (CSM) composites, in which epoxy-based composite showed higher wear volume. The abrasive wear volume of all the composites decreased on irradiating it with laser. These results have been discussed, based on experimental wear data and observed microstructural features of the abraded surfaces.

Mechanical behaviour of rapidly solidified aluminium―silicon ribbon―polyester composites

Metal-polymer composites have been synthesized in recent years [1-3], with a view to achieving a tailored set of properties, which are generally not obtainable in individual materials. These composites are finding a large number of applications because of their improved electrical and thermal properties [4]. Polymerbased composites are generally produced by using various combination of metals and plastics, e.g. impregnation of metal coating with plastics, plastic layers on metallic surfaces, sintering of metal powder and powdered thermoplastics, dispersion of metal powder or metallic ribbons into thermoplastics. It has been reported [5] that the use of layered composites, produced by aluminium and thermoplastic resins, particularly those having sandwich structure, is restricted not only to the finishing step but also can be used as semi-fabricated products. Applications of anodized alucobond [6] (two thin sheets of aluminium bonded to the thermoplastic core of the polyethylene) panels and decorative silhouettes for retail stores are excellent. Festtag and Bolliger [7] have suggested that the scaling layer of aluminium plastics composites can be freely chosen to suit the requirements of food and drug packaging. Rheological behaviour [8-10] and the dynamic and static mechanical properties [11-16] of the epoxy/ metal composites were studied by several researchers. Nicodemo and Nicolais [17] have studied the elastic moduli, stress and strain at break for styreneacrylonitrile polymer (SAN) filled with iron and aluminium powders. They have observed poor adhesion in iron/SAN composites and no adhesion in aluminium/SAN composites. Ceramic reinforcements [18] such as boron and silicon carbide or glass generally offer optimum performance on a specific property, but the size effect problem associated with the brittle materials limited their use. To circumvent the above problem, it has been proposed to use metals such as steel and aluminium in ribbon form [19-22] as the reinforcement in resin materials. Strife and Prewo [18] have studied the mechanical properties of composite made out of high-strength Metglass alloy 2826 MB ribbon as the reinforcement with an epoxy-nylon adhesive, FM-1000, as matrix. They have reported that the above combination of constituents with dissimilar characteristics can produce an increase in axial and transverse tensile strength and elastic modulus. In the present letter it is proposed to reinforce rapidly solidified aluminium silicon, LM 13, alloy ribbon in polymer matrix in order to produce highperformance materials. Composites of various volume fractions of rapidly solidified ribbon with polyester matrix have been produced and the ultimate tensile strength of the composites were determined. Theoretical predictions of ultimate tensile strength (UTS) of the above composites with various volume fractions of metallic ribbons compare with the experimental data. Fracture surfaces of the composites were studied in the scanning electron microscope in order to observe the interfacial bonding between the metallic ribbon and the polymeric matrix. Aluminium-silicon, LM 13, alloy (nominally contains 11 to 13wt% Si lwt% C u l w t % Mg1.5 wt % Ni-0.8 wt % Fe-0.5 wt % Mn and the rest is aluminium) is of interest because it exhibits high strength and a low coefficient of thermal expansion. LM 13 alloy melt was rapidly quenched in the form of ribbon of 160 to 200#m thick and 3mm wide. Ribbons were cast continuously at one production run using a single roll melt spinning technique. Polyester resin was mixed with 1% accelerator and 1% hardener in a beaker. Accelerator, hardner and the resin were obtained from M. P. Polymers, Bhopal, India. Ribbons were kept in layer form one over another for increasing weight fraction in the casting mould (ASTM). After 24h resin setting, specimens were removed from the mould. These were heat set for 2 h at 80°C in an oven. The ultimate tensile strengths of the composites have been measured using an Instron machine. The fractured surfaces of the composites were coated with silver metal to avoid the charging effect, and were observed in the scanning electron microscope. Fig. 1 shows the microstructure of as-received rapidly solidified LM 13, alloy ribbon, as observed

Efficient application of chlorinated paraffin wax-antimony trioxide (Sb2O3) emulsion to sunhemp fibre for fire retardancy

Presentation dune technique de protection contre les incendies du chanvre des Indes, utilise en Inde dans les toits en chaume