synopsisHydrolysis of polyester fabrics with sodium hydroxide has been studied with a view to imparting hydrophilicity and other comfort-related properties to polyeater textiles. E f f e c t of reaction parameters such as treatment time, concentration of alkali, and temperature on the extant of hydrolysis is examined and the modified fabrics are waluated for their important physical, mechanical, and physicochemical properties. The mechanism of hydrolytic degradation of polyester fabrics, as determined by the weight loss, has also been ascertained. Alkali p r o msively degrades polyester by saponification of its ester linkages and results in a loss in weight of the fabric. Weight loss increases linearly with treatment time and nonlinearly with alkali concentration and reaction temperature. A linear correlation exists between strength loss of the fabric and its weight loss. By alkaline hydrolysis, surface hydrophilicity and feel of the fabric are considerably improved, whereas such properties' as moisture regain, crease recovery angle, etc., remain practically unchanged. Attempts have been made to explain the results in terms of modifications in the surface characterktics of polyeater fabrics.

SynopsisThermal analysis has been carried out on polyester (PET) fibers after subjecting them to different physical modifications, such as drawing and heat setting. The relationship between structure and the various thermal transitions observed in the thermograms of poly(ethy1ene terephthalate) has been examined. It has been shown that the endothermic transition near the glass transition region and the exothermic transition a t about 140°C, observed for amorphous PET fibers, may be associated with mesomorphic phase changes. The premelting endotherm is sensitive to the orientation, crystallite size distribution, and thermal prehistory. This transition actually represents melting of smaller crystals and recrystallization into larger crystals. Heat of fusion does not always necessarily represent the actual crystallinity, or order of the fiber prior to differential scanning calorimetry and may be influenced by several factors. The fusion curves give more information regarding crystallite size distribution than crystallinity.

A simple nondestructive method for the quantitative analysis of textile fiber blends has been suggested. The method requires measurement of moisture regain of the blend and its component fibers. Experimental studies have been made with cotton-viscose, polyester-wool, and cotton-wool blends.For comparison, blends have also been analyzed by known chemical methods. It has been found that, in all cases, moisture regain of the blend can be obtained by linear combination of the moisture regains of its constitutent fibers.

We present the temperature dependent elastic and ultrasonic properties of sodium borohydride. The second and third order elastic constants of NaBH 4 have been computed in the temperature range 0-300K using Coulomb and Born-Mayer potentials. The sodium borohydride crystallizes into NaCl-type structure. The computed values of second order elastic constants have been applied to evaluate the temperature dependent mechanical properties such as bulk modulus, shear modulus, tetragonal modulus, Poisson's ratio and Zener anisotropy factor and ultrasonic velocity to predict futuristic information about sodium borohydride. The fracture to toughness ratio (bulk modulus/shear modulus) in sodium borohydride varied from 1.91 to 1.62, which shows its behavioral change from ductile to brittle on increasing the temperature. Then, ultrasonic Grüneisen parameters have been computed with the use of elastic constants in the temperature regime 100-300K. The obtained results have been discussed in correlation with available experimental and theoretical results.

A physicochemical nondestructive method for the quantitative analysis of cotton-polynosic blends is described. The method is based on the moisture regain of cotton, polynosic, and their blends. It is found that the moisture regain is a linear function of the blend composition.