Polycarboxylic acids appear to be the most promising nonformaldehyde durable press finishing agents to replace the traditional N-methylol reagents, 1,2,3,4-Butanetetracarboxylic acid (btca) is the most effective crosslinking agent among the acids investigated, but its exceedingly high cost has prevented its use in the textile industry on a commercial scale. In this research, we evaluate the effectiveness of two polymers of maleic acid, i.e., the homopolymer (pma) and the terpolymer (tpma), along with citric acid (ca) for crosslinking cotton cellulose., pma, tpma, and ca have molecular structures similar to btca, but are more cost effective. We have found that pma and tpma are less effective crosslinking agents for cotton than btca, probably due to the low mobility of the anhydride intermediate formed by pma or tpma to access the cellulosic hydroxyl during the curing process. We have found that the hydroxyl of ca and other α-hydroxylpolycarboxylic acids hinder the esterification of those acids with cellulose. The infrared spectroscopy data indicate that ca esterifies the anhydride intermediates of pma and tpma on cotton fabric under curing conditions. Consequently, ca is transformed from a trifunctional acid to a tetrafunctional one with the formation of an ester linkage with pma or tpma.
Severe tensile strength loss is the major disadvantage of durable press finished cotton fabrics. Such strength losses have been attributed to two main factors: acid-catalyzed depolymerization and crosslinking of cellulose molecules. In this research, we inves tigate the effects of acid degradation and cellulose crosslinking on the tensile strength of cotton fabric crosslinked by polycarboxylic acids. Multifunctional carboxylic acids such as butanetetracarboxylic acid (BTCA) are used as nonformaldehyde crosslinking agents for cotton fabrics. The strength loss caused by acid degradation is an irreversible process, and the magnitude of the loss is determined by the curing temperature and time, the dissociation constants of the acid, and the concentration and pH of the acid solution applied to the fabric. Crosslinking of cellulose molecules by a polycarboxylic acid causes a reversible fabric strength loss, which increases as the degree of crosslink ing increases. The magnitude of tensile strength loss caused by acid degradation and that by crosslinking for cotton fabrics treated with BTCA is measured. Losses caused by crosslinking can be restored after the ester crosslinking is hydrolyzed under alkaline conditions.
We studied the effects of O 2 plasma on the hydrophilic/hydrophobic contrast of film substrates. PET (polyethylene terephthalate) and FEP (fluorinated ethylene propylene) films were treated by O 2 plasma, and the surface of the films was investigated using atomic force microscopy(AFM), X-ray photoelectron spectroscopy (XPS), and contact-angle and surface energy measurements. Surface energies were calculated from the measured contact angles between several solutions and the films based on the geometric mean and Lewis acid-base method. The contact angle of PET films treated by O 2 plasma decreased with increasing treatment time in water and surfactant solution, and surface energy increased with increasing polar component of surface tension of the film. In contrast, the contact angle of the O 2 plasma-treated FEP film decreased, and surface energy decreased with decreasing nonpolar component of surface tension of the film.
In this study, multivariate statistical analysis was applied to analyze the trend of water quality and water quality in the Fourth reservoir over the last 10 years. Correlation analysis between water quality variables showed that, the correlation coefficient between COD and TOC, which is an indirect indicator of organic matter, showed a high correlation of 0.608, while water temperature showed a positive correlation with pH of 0.515 and a negative correlation with DO of -0.716. Principal component and factor analyses showed that the four major components were extracted from the total water quality and contributed 72.9% of the total variance. When analyzed for cyanobacteria occurrence, three major components were extracted and contributed 67.2% of the total variance. Factor loadings analysis of water quality variables on the factors identified the first factors as COD and TOC. Water quality of the Fourth reservoir was found to be influenced by seasonal effects such as rainfall and organic matter, in addition to the effects of phytoplankton proliferation and nutrient influx.
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