Green composite methods

Nan and Weng (1999) have developed a Green function method to determine self-consistently the effective magnetostrictive properties of composites. The authors claim that their method, in principle, can be used to study the effects of material constants and microstructure, such as anisotropy, particle shape and orientation relative to the applied magnetic field. 

Two types of environmentally friendly jute fibre reinforced green composites have been studied. These are based on Mesua ferrea L. seed oil-based poly(urethane ester) and poly(urethane amide) resin blends with commercially available partially butylated melamine-formaldehyde and epoxy resins by solution impregnation and hot-curing methods. The composites were cured at a temperature of about 130-140°C under a pressure of 35.5 kg cm for around 2 h.The physical, mechanical and chemical properties of the epoxy-modified polyurethane composites were better than those of the MF-modified composites. They also possessed excellent chemical resistance and hydrolytic stability in water, acid and salt solutions, making them useful for low load-bearing applications. 

Electrophoretic infiltration is a novel technique for the fabrication of fiber reinforced composites used by Kooner et al [234]. The technique involves arranging the fibers as one of the electrodes such that deposition of the colloidal ceramic occurs in the fiber preform. This method was investigated for the carbon fiber reinforced Si3N4 composite system and produced green composite microstruetures with good infiltration uniformity and fiber distribution, with hardly any macro defects. 

The main objective of our studies was to obtain green composites from corn starch matrix and various conventional [73, 76, 77], and non-conventional cellulose sources [78]. Previously, corn starch (St) was converted to starch microparticles (StM). Further, different organic acids (adipic, malic, tartaric) were used for treatment of StM in order to obtain chemically modified starch microparticles (CMSt) according to literature data [72]. After casting and water evaporation, the starch-based films were investigated by means of X-ray diffraction and FTIR spectroscopy methods. Opacity and water uptake of starch-based films were also evaluated. 

There are several steps that need to be followed in developing green composites using starch-based resins. First, fabrication methods and variables such as pressure and temperature need to be optimized because the material is quite new and unknown. The second step is to improve the composite properties through treatment and new techniques. Once the problems are clearly defined, it is easier to set up... 

Table 12.10 Comparison of tensile properties of curaua fiber green composite fabricated using DM and PS methods [28].

Moreover, highty concentrated alkali treatment (10 wt%) was applied to curaua fibers to improve mechanical properties of green composites. Tensile test results showed that alkali-treated liber composites increased in fracture strain twice to three times more than untreated fiber composites, without a considerable decrease in strength. These results showed that highly concentrated alkali treatment is a suitable method for improving fracture strain and toughness of these composites. 

Shih et al. [27] fabricated green composites with fiber recycled from disposable chopsticks and PLA matrix by melt-mixing method. Mechanical tests showed that the tensile strength of the composites markedly increased with the fiber content, reaching 115 MPa in the case of being reinforced with 40 phr fibers, which was about three times higher than the neat PLA. 

Recently, Flores-Hernandez et al. (2014) developed a green composite chitosan-starch as matrix and keratin biofibers as reinforcement. Keratin biofibers from feathers are non-abrasive, eco-friendly, biodegradable, renewable, and insoluble in organic solvents and also have good mechanical properties, low density, hydrophobic behavior, ability to dampen sound, warmth retention, and finally low cost (Meyers et al., 2008 Martinez-Hernandez and Velasco-Santos, 2011). Flores-Hernandez etal. (2014) developed the ecocomposites using three different kinds of keratin reinforcement short and long biofibers and rachis particles. These were added separately at different concentrations to the chitosan-starch matrix and the composites were processed by a casting/solvent evaporation method. 

Properties. The composition of shale oil has depended on the shale from which it was obtained as well as on the retorting method by which it was produced. Properties of shale oils from various locations are given in Table 8. A comparison of a Green River shale oil and a Michigan Antrim shale oil, retorted under similar conditions, is given in Table 9. 

B. D. Green. Method for creating dense drilling fiuid additive and composition therefor. Patent WO 0168787A, 2001. 

The colour reaction of cholesterol and cholesterol esters with acetic anhydride and concentrated sulphuric acid provides the basis of the method attributed to Liebermann and Burchard. This reaction in not entirely specific for cholesterol or its esters because other sterols will also react. In its original form the reagent consists of acetic anhydride, concentrated sulphuric acid and glacial acetic acid and the intensity of the green colour is affected by the proportions of the reagents and the amount of water present. It is possible to achieve an increase in sensitivity if the reagent contains ferric ions. Various modifications of reagent composition have been used and some methods are fluorimetric. 

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