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ABSTRACT
The effect of NaOH mercerization on the crosslinking properties of 1,2,3,4-butanetetracarboxylic acid (BTCA) on ramie yarn is studied, with emphasis on mercerization tension. NaOH at mercerization strength decrystallizes the ramie fibers, resulting in a higher accessibility to BTCA. Due to the change in fiber orientation caused by mercerization, tension mercerized and crosslinked ramie yarn shows a higher tenacity than the crosslinked control, while the low-tension or slack mercerized and crosslinked ramie yarn exhibits more serious tensile strength loss than the crosslinked control.
Ramie fibers offer excellent properties such as high tensile strength and excellent thermal conductivity when used as textile materials. However, they suffer from poor elasticity and harsh handle, particularly the fabrics made from ramie fibers, which have a very low wrinkle recovery angle. To be competitive, these fabrics must survive the newest technological developments at all stages of production, especially the process of dyeing and finishing. Early research on alkalization, grafting, and cellulase treatments mostly focused on improvements in elasticity and handle of ramie yams and fabrics. Among these treatments, mercerization had been extensively studied, particularly the fine structure of ramie fibers. X-ray studies showed that mercerization of ramie results in a complete conversion from cellulose I to cellulose II, together with a decrease in the crystallinity to 50% [1]. Warwicker [17] pointed out that slack mercerization at 0 or 20 deg C causes a decrease in orientation, whereas tension mercerization increases orientation. Sao [15] and Liu [8] found that ramie approaches a maximum swelling at around 16% NaOH, along with a maximum change in the crystalline index, orientation, density, and absorption. When the concentration of NaOH is below 12%, these properties change little. The physical properties of the mercerized ramie yam have also been investigated [2, 3, 5, 8], and the results show that tension mercerization improves tensile strength while slack mercerization decreases it, causing a much higher elasticity in the ramie yarn.
Hitherto, there have only been three reports on the wrinkle-free treatment of ramie fabrics. The crosslinking agent used by Naval [10] was DMDHEU, while Oh [12] applied DMDHEu and N-methylolacrylamide (NMA) on ramie fabric with an in-situ polymerization and crosslinking process. In a recent report, Oh [13] treated ramie fabric with glyoxal and polyethyleneglycol (PEG) 600...