Hyung-Min Choi

Cotton Nonwovens as Oil Spill Cleanup Sorbents

We examined partial or complete replacement of synthetic sorbents by cotton- containing nonwovens for use in oil spill cleanup. The results indicate that with light crude oil, oil sorption capacities of the needlepunched cotton-containing sorbents were slightly greater than those of sorbents made from 100% polypropylene fibers. If necessary, a small portion of polypropylene fiber could be incorporated into nonwovens to increase mechanical strength properties and to maintain fabric integrity. The cotton- containing sorbents were reusable after a simple mechanical compression to remove oil. They also floated in an artificial seawater bath for a long period of time. We found that oil sorption of cotton fiber was controlled by adsorption on the fiber surface and capillary action through its lumen. Contrarily, the main mechanism for polypropylene was through capillary bridges between fibers. Detailed evaluation using an environ mental scanning electron microscope confirmed this mechanism. Individual bundles of both cotton and polypropylene fibers sorbed more oil than did the needlepunched nonwoven fabrics prepared from the respective fibers. In addition, sorption decreased as needling density increased. This study provides preliminary data for investigating other cotton nonwoven constructions with improved oil sorption properties.

Synthesis of a Quaternary Ammonium Derivative of Chitosan and Its Application to a Cotton Antimicrobial Finish

A quaternary ammonium derivative of chitosan, N-(2-hydroxy)propyl-3-trimethy lammonium chitosan chloride (HTCC), is synthesized as an antimicrobial finish for cotton using a reaction of glycidyltrimethylammonium chloride (GTMAC) and chitosan. Results indicate that the degree of substitution (DS) in HTCC calculated by chloride content is a function of the reaction temperature and mole ratio of GTMAC and NH2 in chitosan. Excess amounts of GTMAC are generally needed to obtain a water-soluble fraction of HTCC. A minimum DS of 0.6 is needed to yield water-soluble HTCC. Syn thesized HTCC is analyzed by FTIR, H 1-NMR, TGA, and x-ray diffraction techniques. At very low concentrations, such as 0.025% owb, HTCC shows superior antimicrobial ac tivity indicated by an almost 100% bacterial reduction, whereas 1 % owb chitosan shows only 30% bacterial reduction. Since HTCC is soluble in water, we have examined several methods to increase the laundering durability of cotton treated with HTCC. Among them, application of a nonionic binder considerably improves the laundering durability of HTCC-treated cotton.

Effect of deacetylation on sorption of dyes and chromium on chitin

Deacetylated chitins (10.7-67.2fl ) were prepared by alkaline hydrolysis to determine an optimal degree of deacetylation (DD) which can effectively remove four dyes and chromium ions from textile effluent. Sorption isotherms were carried by varying the treatment time, pH, and initial concentration of dyes or chromium ions. Experimental results were analyzed in three ways: (1) equilibrium sorption capacity and sorption rate constant, (2) Langmuir isotherms, and (3) separation factor. Results indicated that except for the chitin with a 67.2% DD, rate and capacity of the dye sorption on the chitin increased with the increase of the DD in chitin for each pH but decreased with the increase of pH for each deacetylated chitin. This was mainly due to the increase of-NH 3 + groups in chitin with a high DD and the low pH of the system. On the contrary, dye desorption from the deacetylated chitin was highly effective at 80°C and pH ≥ 10, which could facilitate the reduction of-NH 3 + ions and the increase of electrostatic repulsion. The number of chromium ions sorbed on the chitin also increased with the increase of the DD at a specific time. Therefore, by controlling the DD of the deacetylated chitin maximum efficiency can be achieved in the removal of dyes and metal ions from textile effluent.

Antibiotic Treatment of Silk to Produce Novel Infection-Resistant Biomaterials

Dye-like applications of antibiotics to silk produce infection-resistant materials for potential use in biomedical applications. Two antibiotics, doxycycline (doxy) and cipro floxacin (cipro), are applied under a variety of conditions to silk and to silk that has previously been hydrolyzed at 40°C for 20, 40, and 60 minutes. FTIR spectroscopic analyses indicate that the drastically increased sorption of antibiotics by hydrolyzed silk is attributable to both chemical and conformational changes that occur with the hydrolysis. The high sorption of doxy by hydrolyzed silk does not necessarily yield a more infection- resistant material, as determined by a zone of inhibition test. Conversely, the same hydrolysis considerably increases both the sorption of cipro and the zone of inhibition of cipro-treated silk dyed at 65 and 85°C.

Nonphosphorus Catalysts for Formaldehyde-Free DP Finishing of Cotton with 1,2,3,4-Butanetetracarboxylic Acid Part II: Sodium Salts of Fumaric, Maleic, and Itaconic Acids

We examined catalyrtic activities of mono- or disodium salts of fumaric, maleic, and itaconic acids for the reaction of 1,2,3,4-butanetetracarboxylic acid ( BTCA ) with cotton cellulose. Evidence for esterification and crosslinking of cellulose with BTCA in the presence of these carboxylic acid salts was shown by improved durable press rating and conditioned wrinkle recovery angles of the treated fabric and the presence of ester groups in the treated fabric by FTIR analyses. In addition, FTIR and FT- Raman analyses revealed that these carboxylic acid salts did not participate in formation of permanent linkages with cellulose and BTCA.

Nonformaldehyde Crease-Resistant Finishing of Ramie with Glyoxal in the Presence of a Swelling Agent

The feasibility of glyoxal treatment for ramie fabric in the presence of a swelling agent is studied. Adding polyethylene glycol (PEG) 600 or a higher molecular weight PEG to the glyoxal finishing bath provides an optimum balance between the wrinkle recovery angle and strength retention by maximizing ramie swelling during the crosslinking reaction. Adding PEG also increases the water of imbibition, moisture regain, whiteness index, and color strength of treated ramie fabrics. The durability of glyoxal finished fabric in the presence of PEG is also acceptable during multiple launderings. Therefore, glyoxal treatment with PEG can be used for crease-resistant finishing of ramie and ramie-blended fabrics to obtain superior performance properties.

One-bath dyeing and nonformaldehyde durable press finishing of cotton using dialdehyde and a monochlorotriazinyl reactive dye

Cotton is subjected to one-bath dyeing and durable press finishing (ODF) with dialde hyde and a monochlorotriazinyl reactive dye. Results indicate that an optimal curing temperature is 150°C to simultaneously fix dialdehyde and reactive dye on cotton.- Changing the immersion temperature and time (40°C for 20 minutes) in the treatment bath greatly enhances the efficiency of the ODF process with dialdehyde and reactive dye.

Synthesis and characterization of a dyeable bio-based polyurethane/branched poly(ethylene imine) interpenetrating polymer network with enhanced wet fastness

Bio-based polyurethane is synthesized from biodegradable polycaprolactone, methylene diphenyl diisocyanate and 1,4-butanediol. The bio-based polyurethane is blended with branched polyethyleneimine by a solution casting method and further treated with glutaraldehyde. From nuclear magnetic resonance, Fourier-transform infrared spectroscopy, leaching tests and contact angle measurements, it was found that a semi-interpenetrating polymer network structure is induced by the glutaraldehyde treatment of the bio-based polyurethane/branched polyethyleneimine blend film, which resulting from the crosslinking of branched polyethyleneimine by imine bonds formed from the amine-aldehyde reaction between branched polyethyleneimine and glutaraldehyde. In addition, the glass transition temperature, Young’s modulus and the shape retention results show that the mechanical strength of bio-based polyurethane, which is weakened by the plasticizing effect of branched polyethyleneimine, is restored by the formation of the semi-interpenetrating network structure. We found that the bio-based polyurethane/branched polyethyleneimine with a semi-interpenetrating network shows a much higher affinity for Acid Red 4 than bio-based polyurethane, and the wet fastness of dye is significantly improved by the formation of the semi-interpenetrating network.