P.A. Sreekumar

Study of Wheat-Flour-Based Agropolymers: Influence of Plasticizers on Structure and Aging Behavior

ABSTRACTWheat-flour-based agropolymers are prepared using an extrusion method. The morphology of the native and extruded wheat flours are analyzed by scanning electron micrography (SEM). During plasticization using water (9%, w/w) and glycerol (12.8%, w/w), a change in morphology of native wheat flour occurs. The structure of these materials was investigated by X-ray diffraction (XRD) with special reference to the amount of plasticizers used, such as water and glycerol molecules. The introduction of these plasticizers decreases the crystallinity rate and also increases the average distance between chains in the remaining vitreous phase of the extruded wheat flour. Replacing water molecules with glycerol reduces the crystalline phase and diminishes the average size of crystalline structures. The plasticization effects were confirmed by mechanical investigations. Indeed, increasing the amount of glycerol from 12.8 to 20% decreases the stress at failure and the tensile modulus, while the strain at failure in...

Thermal behavior of chemically treated and untreated sisal fiber reinforced composites fabricated by resin transfer molding

Using thermogravimetric analysis (TGA), the thermal behavior of sisal fibers and sisal/polyester composites, fabricated by resin transfer molding (RTM), has been followed. Chemical treatments have been found to increase the thermal stability, which has been attributed to the resultant physical and chemical changes. Scanning electron microscopy (SEM) and infrared (FT-IR) studies were also performed to study the structural changes and morphology in the sisal fiber during the treatment. The kinetic studies of thermal degradation of untreated and treated sisal fibers have been performed using Broido method. In the composites, as the fiber content increases, the thermal stability of the matrix decreases. The treated fiber reinforced composites have been found to be thermally more stable than the untreated derivatives. The increased thermal stability and reduced moisture behavior of treated composites have been correlated with fiber/matrix adhesion.

Viscoelastic and thermal properties of eco-friendly composites fabricated by resin transfer molding

This article reports the result of the effect of banana fiber on the dynamic mechanical and thermal properties of polyester composites. Composites were prepared using resin transfer molding by varying the fiber content (20, 30, 40, and 50 vol.%). Studies revealed that increase in the fiber content will increase the storage modulus (E′) and the maximum is given by the composites having a fiber loading of 40 vol.% at all temperature ranges. The peak height of loss modulus (E″) and damping curves (tan δ) were lowered with respect to the fiber content. Glass transition temperature (Tg) calculated from the E″ and tan δ shifted toward high temperature with the addition of fiber. An attempt has been made to correlate the experimental and theoretical values of storage modulus and tan δ. Thermogravimetric analysis showed that incorporation of fiber to the matrix will affect the thermal stability of the composites.

Properties and Biodegradation Nature of Thermoplastic Starch

For the last few decades, the usage of plastic increased because of its specific properties such as low cost, light weight, high strength, non-biodegradability, durability, non corrosive nature, process ability and high energy effectiveness. Hence these plastics can be used for various application which includes household articles to aeronautic sector. Now a day it’s difficult to imagine a life without plastic which are mostly derived from crude oils and natural gas. Among the various polymers, polyethylene, polypropylene and polystyrene are used greatly for food packaging, biomedical field and in agriculture. According to statistics, from 1950 onwards, 9% of growth can be seen globally, in the production and consumption of plastics. In 1950 the overall production of plastic was 1.5 million tones while it reached 245 million tones in 2008.