Hydroxide reinforcement methods

Some of these features are illustrated in Figures 14-18. A rather typical literature plot of current efficiency vs, sodium hydroxide concentration for perfluorosulfonate membranes is shown in Fig. 14. Nation 427 is a 1200-EW sulfonate membrane with fabric reinforcement. Poor hydroxide rejection occurs at catholyte concentrations above 10 wt % but a minimum is seen at higher concentrations, wtih increasing current efficiency from 28 to 40% caustic (9-14 M). The current efficiency of a 1200-EW homogeneous perfluorosulfonate film is shown in more detail over this concentration region in Fig. 15. Sodium ion transport number niol F ), which is equivalent to caustic current efficiency, is plotted vs. both brine anolyte and caustic catholyte concentration. These values were determined using radiotracer techniques, which have proven to be rapid and accurate methods for the determination of membrane performance. " " " A rather sharp maximum is seen at 14 M NaOH, and the influence of brine con-... 

Several studies have been made to optimize the properties of natural fiber-reinforced PLA composites from the point of view of fiber-matrix adhesion. Pretreatment of fibers, such as chemical modification, seems to be the most promising approach, in which covalent bonds are formed between the fiber and matrix. One of the most common and efficient methods is alkali treatment (for example, with 2% sodium hydroxide aqueous solution) of fibers, which has been used to... 

Wang et al. [54] studied the effect of WG on the degumming process of jute fiber in order to improve the fiber properties. It was found that the WG concentration, sodium hydroxide concentration, and treatment time were the three most important parameters for the degumming process. The authors concluded that the degumming process was an effective method for ranoving hemicellulose, lignin, pectin, and certain other noncellulose materials. WG or alkali treatments depend on several variables such as the concentration of the alkaline solution, temperature, and the duration of the treatment. These variables directly affect the adhesion between the fiber and the matrix, and consequently, they also affect the mechanical and thermal properties of the fiber-reinforced composites. 

A traditional chemical extraction process that uses an alkaline sodium hydroxide solution has also been applied to the same wooden material. Fibers extracted by the two methods have been used as reinforcement for the two commercial polypropylenes the conventional isotactic polypropylene, and maleic anhydride functionalized isotactic polypropylene (iPPMA). The composites have also been subjected to a water absorption treatment. To assess the reinforcement effect of fibers, composite characterization techniques and determination of mechanical properties have been performed with particular attention to the fiber-matrix interfacial characteristic. The results have been compared with those of short glass reinforced polypropylene composites. 

Alkali treatment of natural fibers, also referred to as mercerization, is an old and most widely used method for modifying ceUulose-based natural fibers [30-36]. The most favorable alkali solution for mercerization is sodium hydroxide (NaOH) aqueous solution. The effect of alkali treatment on the properties of the composite as well as on the natural fibers strongly depends on alkali solution type, alkali concentration, treatment time, treatment temperature, and treatment tool. Alkali treatment may cause fibrillation of pristine natural fibers, resulting in the breakdown of individual fibers with smaller fiber diameter. This phenomenon can not only increase the aspect ratio of reinforcing natural fibers but also roughen the fiber surfaces. As a result, the fiber-matrix interfacial adhesion may be enhanced and the... 

Potassium Hydroxide (cont) 10 50 5 Attacked low density tensile and elongation retained ASTM D543 test methods Rulon J Furon Specimen TFE with proprietary reinforcement... 

In order to consider effective strategies for the recovery and reuse of plastics recyclates, a quantitative method is described for the characterisation of polyester-based moulding compounds. Analytical procedures are described for the quantification of fibre, filler and fire retardant contents in polyester moulding compounds containing calcium carbonate filler, glass fibre reinforcement, and aluminium hydroxide flame retardant. 3 refs. 

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