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Introduction: Laryngopharyngeal herpes simplex virus infection is rare and presents typically in the supraglottis. Findings on presentation can range from small mucosal lesions to fungating obstructive masses mimicking neoplasm. Laryngopharyngeal herpes is a medically treated disease.Objectives: Identify potential treatment in cases that are refractory to antiviral medications.Methods: Individual case with treatment adapted from other case report.Case Presentation: We report a case of bulky, obstructive supraglottic and glottic herpes virus laryngitis that presented with dysphonia, dysphagia, and airway complaints resistant to acyclovir analogues that was treated effectively with intralesional cidofovir injection.Conclusions: Our promising initial response suggests a potential novel treatment for this unusual condition.

The use of flame retardant finishing becomes necessary for cotton fleece to pass the U.S. government regulation ‘Standard for the Flammability of Clothing Textiles’ (16 CFR 1610). The objective of this research was to reduce the flammability of cotton fleece using a flame retardant finishing system consisting of a hydroxyl-functional organophosphorus oligomer (HFPO) as a flame retardant and 1,2,3,4-butanetetracarboxylic acid (BTCA) as a bonding agent. We investigated the role triethanolamine (TEA) played as a reactive additive in the HFPO/BTCA finishing system on cotton fleece. We also applied micro-scale calorimeter (MCC) to study the effectiveness of HFPO and BTCA in reducing the flammability of cotton. BTCA alone was able to reduce the peak heat release rate (PHRR) of cotton as demonstrated by the MCC data. Combining BTCA with HFPO decreased PHRR further and also significantly reduced the decomposition temperature and the temperature at PHRR of cotton. The cotton fleece treated with HFPO/BTCA/TEA passed the federal regulation (16 CFR Part 1610) and achieved ‘Class 1’ flammability. The treated cotton fleece was durable to multiple home laundering cycles. The use of TEA enhanced the performance of HFPO/BTCA and the treatment caused no significant changes in fabric physical properties.

Most cotton fleece fabrics are not able to meet the federal flammability standard for general apparel (16 CFR 1610). In this research, we applied three carboxylic acids, i.e., succinic acid (SUA), malic acid (MLA), and tartaric acid (TTA), as flame retardant finishing systems for cotton fleece. We found that all three acids are able to esterify cotton in the presence of sodium hypophosphite as the catalyst, and SUA is the most reactive and the most hydrolysis-resistant when it is bound to cotton. The a-hydroxyl group with both MLA and TTA appears to hinder esterification and to facilitate hydrolysis for MLA and TTA bound to cotton. All three bifunctional carboxylic acids are effective in reducing the flammability of cotton fleece from ‘Class 3’ to ‘Class 1’. The micro-scale combustion calorimetry data reveal that SUA reduces cotton flammability by reducing its peak heat-release rate and heat-release capacity. The cotton fleece treated with SUA also has the highest bursting-strength retention and the least fabric yellowing.

Cotton fleece does not meet the federal flammability standard (16 CFR Part 1610: `Standard for the Flammability of Clothing Textiles') without chemical treatment. In this research, the chemical reactions of maleic acid (MA) on cotton in the presence of sodium hypophosphite (NaH2PO2) and the use of the combination of MA and NaH2PO2as a flame retardant finishing system for cotton fleece are investigated. It has been found that MA esterifies cotton cellulose at relatively low temperatures in the presence of NaH2PO2as catalyst, and that MA esterified to cotton is able to further react with NaH2PO2at higher temperatures (≥150°C), which bonds phosphorus to the cotton cellulose. The reactions between MA and NaH2PO2on cotton also lead to the cross-linking of cotton cellulose. The treatment using the combination of MA and NaH2PO2is effective in reducing the flammability of cotton fleece from `Class III' to `Class I' (16CFR1610). This is a nonformaldehyde and low cost flame retardant finishing system for cotton fleece. The treated cotton fleece still maintains `Class I' flammability after 20 home laundering cycles.

Multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA), have been used as durable press finishing agents to produce wrinkle-resistant cotton. In our previous research, we used BTCA as a nonformaldehyde bonding agent in the flame retardant finishing system based on a hydroxy-functional organophosphorus oligomer (HFPO) for cotton. In this research, we investigate the application of HFPO to the 65%/35% Nomex/cotton blend fabric using BTCA as a bonding agent and triethanolamine (TEA) as a co-reactant. We found that the addition of TEA in the flame retardant finishing system improves the hydrolysis resistance of the HFPO bound to the Nomex/ cotton blend and enhances the flame retardant performance of HFPO by means of phosphorus—nitrogen synergism. Moreover, TEA reduces the deposit of calcium salt on the treated fabric during laundering by esterifying the free carboxylic acid groups on cotton. The Nomex/cotton blend fabric treated with the HFPO/BTCA/TEA system shows high flame retardant performance at relatively low add-on levels. It is a completely nonformaldehyde flame retardant finishing system.

Two bifunctional aldehydes (i.e., glyoxal and glutaraldehyde) are used as the crosslinking agents to improve paper wet strength in the presence of fully hydrolyzed poly(vinyl alcohol) (PVA) as a co‐reactant. These bifunctional aldehydes alone improve paper wet strength but diminish its folding endurance. The use of PVA as a co‐reactant not only improves paper wet strength but also increases its dry strength and folding endurance. Glutaraldehyde is able to impart much higher levels of wet strength to the treated paper than glyoxal when a catalyst is present. The wet strength of the treated paper increases as the amount of PVA added is increased, and it also increases as the molecular weight (Mw) of the PVA increases. The data suggest that the reaction between glutaraldehyde and PVA promotes the formation of interfiber crosslinking, thus improving the wet strength without diminishing the flexibility of the treated paper. The use of a catalyst is critical to achieve high levels of durable wet strength of the treated paper. We studied the effects of different Lewis acids as the catalysts for crosslinking of pulp cellulose by glutaraldehyde and found that Zn(NO3)2 is the most effective one. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1673–1680, 2004

Multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA), are effective crosslinking agents for cotton cellulose and have become the most promising nonformaldehyde durable press (DP) finishing agents to replace the traditional formaldehyde-based dimethyloldihydroxylethyleneurea (DMDHEU) and its derivatives. DP finishing imparts wrinkle resistance to cotton fabrics and also severely reduces the strength and abrasion resistance of finished fabrics. In this research, we investigated the use of poly(vinyl alcohol) (PVA) as an additive to improve the abrasion resistance of the cotton fabric crosslinked by BTCA. We found that addition of PVA improves the abrasion resistance of the crosslinked cotton fabric when the concentration of PVA exceeds 0.6% in the finish solution. We also found that the use of PVA as an additive has no negative effect on the wrinkle recovery angle (WRA), DP rating, and tensile strength of the treated cotton fabric. This is probably because the molecules of PVA stay on the surfaces of the cotton fibers due to their large molecular sizes. PVA competes with cellulose to esterify BTCA, thus reducing the number of crosslinkages formed on the cotton fiber surface. The reaction of PVA and BTCA may also form a protective layer on the fiber surface, thus reinforcing the mechanically weak points on the fiber surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3940–3946, 2004

It is necessary to use a crosslinking agent to bond a flameretarding hydroxy-functional organophosphorus oligomer (FR) to cotton so that the flame resistance of the treated cotton fabric can be durable to multiple homelaundering. Both dimethyloldihydroxyethyleneurea (DMDHEU) and melamine– formaldehyde (M-F) have been used as the binding agents between FR and cotton. The vertical flammability, limiting oxygen index (LOI) and phosphorus content after different numbers of laundering cycles as well as the wrinkle resistance and tensile strength of the cotton fabric treated with FR/DMDHEU and FR/M-F was investigated and compared in this research. We found that DMDHEU is more effective for crosslinking cotton cellulose and for crosslinking between FR and cotton than M-F. We also found that the bonding formed by DMDHEU between cotton and FR is more durable to multiple laundering cycles than that formed by M-F. M-F is a more effective nitrogen provider than DMDHEU to enhance the flame retarding performance of the treated cotton fabric through phosphorus–nitrogen synergism, therefore the presence of M-F in the flame retardant finishing system significantly increases the flame resistance of the treated fabric. DMDHEU, as an effective crosslinking agent for cotton, causes more fabric strength loss than M-F.

The combination of a hydroxy-functional organophosphorus flame retardant agent (FR) and melamine–formaldehyde (M–F) was used as a durable flame retardant finishing system for cotton fabrics. M–F functions as a binder between FR and cotton cellulose, thus making this flame retardant system durable to home laundering. M–F also provides nitrogen to this system, therefore enhances its flame retarding performance by means of phosphorus–nitrogen (P–N) synergism. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles as well as other materials. In this research, we investigated the correlation between LOI and the phosphorus content on the cotton fabric treated with the durable flame retarding system described above. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy (ICPAES). We developed a statistical model to predict the LOI of the treated cotton fabric based on the phosphorus concentration and the concentrations of the M–F in the finish solutions.

The combination of a hydroxyl-functional organophosphorus flame-retarding agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame-retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame-retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame-retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003

Polycarboxylic acids have been used as nonformaldehyde durable press finishing agents for cotton fabrics. Previously, we found that itaconic acid (IA) polymerized in situ on cotton fabric and also in an aqueous solution in the presence of a K2S2O8/NaH2PO2 initiation system. Both poly(itaconic acid) (PIA) and the polymer formed by in situ polymerization of IA are able to crosslink cotton cellulose, thus imparting wrinkle resistance to cotton. In this research, we compared the performance of the cotton fabric crosslinked by PIA and that crosslinked by in situ polymerization of IA. The fabric treated with PIA and that treated with IA had similar wrinkle recovery angles. The cotton fabric treated with IA, however, lost more tensile strength than that treated with PIA due to cellulose degradation. We determined the magnitude of the fabric tensile strength loss attributed to crosslinking by separating the tensile strength loss due to cellulose degradation from the total tensile strength loss, and found that the tensile strength loss caused by crosslinking for the fabric treated with PIA was significantly higher than that for the fabric treated with IA. This can probably be attributed to more concentrated crosslinkages formed on the near surface of the PIA-treated cotton fabric. PIA had poorer penetration into the amorphous cellulose region in fiber interior due to its much larger molecular size, thus increasing its concentration on the fabric's near surface. The data also suggest that more concentrated crosslinkages on the fabric surface reduced fabric abrasion resistance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2023–2030, 2003

Polycarboxylic acids have been the most promising durable press finishing agents for cotton to replace traditional formaldehyde-based reagents. Among the various polycarboxylic acids investigated in recent years, 1,2,3,4-butanetetracarboxylic acid (BTCA) has been the most effective crosslinking agent. Cottons treated with BTCA have shown superior durable press performance with high levels of laundering durability. In this research, we analyze a reagent grade and an industrial grade BTCA using elemental analysis and acid-base titration. The titration data indicate that the industrial grade product contains approximately 95% BTCA. The two BTCA products are studied by FTIR and FT-Raman spectroscopy, proton magnetic resonance spectroscopy (1H-NMR), mass spectroscopy (MS), and liquid chromatography/mass spectros copy (LC/MS). All the instrumental analysis data indicate the low level of impurities in the industrial BTCA. Cotton fabrics treated with the two products show similar durable press performance, indicating that the differences in effectiveness for crosslinking cotton between these two BTCA products are insignificant. The data also show that the impurity in the industrial grade BTCA does not cause fabric yellowing.

In recent years extensive efforts have been made to use multifunctional carboxylic acids as formaldehyde-free crosslinking agents for cotton to replace the traditional formaldehyde-based N-methylol reagents. In our previous research we found that a polycarboxylic acid esterifies cellulose through the formation of a five-membered cyclic anhydride intermediate by dehydration of two adjacent carboxyl groups. In this research we used Fourier transform IR (FTIR) spectroscopy to study the formation of cyclic anhydride intermediates and crosslinking of cotton by 1,2,4-butanetricarboxylic acid (BTA) and 1,2,3-propanetricarboxylic acid (PCA). BTA and PCA form five-membered cyclic anhydrides in the same temperature range. Both acids form the anhydrides at lower temperatures when a catalyst is present. When an acid molecule is bonded to cotton through an ester linkage, only PCA is able to form a second anhydride intermediate. We found that PCA is a more effective crosslinking agent, and it imparts higher levels of wrinkle resistance to the cotton fabric than BTA. Therefore, the formation of a five-membered cyclic anhydride by a polycarboxylic acid accelerates the esterification of cotton by the acid. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2142–2150, 2001

In this research, we used a new redox free radical initiation system consisting of potassium persulfate (K2S2O8) and sodium hypophosphite (NaH2PO2). In the presence of NaH2PO2, the thermal decomposition of K2S2O8 is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K2S2O8/NaH2PO2 initiation system in an aqueous solution, and monitored the polymerization process with FT-Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disappearance of the characteristic bands of MA as the thermal decomposition of K2S2O8 progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001

Durable press (DP) finishing, a process widely used by the textile industry to produce wrinkle-resistant cotton fabrics, causes considerable loss of fabric abrasion resistance. N-methylol compounds such as dimethyloldihydroxylethyleneurea (DMDHEU) are traditional durable press finishing agents. In recent years, multifunctional carboxylic acids such as 1,2,3,4-butanetetracarboxylic acid (BTCA) have been used as nonformaldehyde alternatives. In this research, we investigate the loss in fabric abrasion resistance caused by degradation and crosslinking of cellulose. Treatment of cotton by a polycarboxylic acid or a catalyst for DMDHEU results in a significant loss of its abrasion resistance. The lost abrasion resistance of cotton treated with BTCA is attributed to irreversible acid-catalyzed depolymerization and reversible crosslinking of cellulose molecules. We have removed the crosslinking of BTCA-treated cotton fabric with alkaline hydrolysis, thus determining separately the magnitude of lost fabric abrasion resistance due to the two different factors. For a warp-faced twill weave cotton, the reduced abrasion resistance in the warp direction is more severe than in the filling direction.

Cationic copolymers of butylacrylate (BA) and [3-(methacryloylamino)-propyl]trimethylammonium chloride (MAPTAC) were synthesized by free-radical-solution polymerization in methanol and ethanol. An FT-Raman Spectrometer and NMR were used to monitor the polymerization process. The copolymers were characterized by light scattering, NMR, DSC, and thermogravimetric analysis. It was found that random copolymers could be prepared, and the molar fractions of BA and cationic monomers in the copolymers were close to the feed ratios. The copolymer prepared in methanol had a higher molecular weight than that prepared in ethanol. As the cationic monomer content increased, the glass-transition temperature (Tg) of the copolymer also increased, whereas the thermal stability decreased. The reactivity ratios for the monomers were evaluated. The copolymerization of BA (M1) with MAPTAC (M2) gave reactivity ratios such as r1 = 0.92 and r2 = 2.61 in ethanol as well as r1 = 0.79 and r2 = 0.90 in methanol. This study indicated that a random copolymer containing a hydrophobic monomer (BA) and a cationic hydrophilic monomer (MAPTAC) could be prepared in a proper polar solvent such as methanol or ethanol. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1031–1039, 2001

In previous research, we found that sodium hypophosphite (NaH2PO2) reduces the temperature required for the formation of anhydride intermediates by polycarboxylic acids. We also found that a chemical reaction between the anhydride intermediate of 1,2,3,4-butanetetracarboxylic acid (BTCA) and NaH2PO2takes place when the temperature rises above 200°C. In this research, we use Fourier transform infrared (FTIR) spectroscopy and thermal analysis to confirm that NaH2PO2reacts with cis-1,2-cyclohexanedicarboxylic anhydride (CHDN) at temperatures above 170°C. NaH2PO2catalyzes the formation of the cyclic anhydride intermediate by 3-butene-1,2,3-tricarboxylic acid (BTTA) on cotton. In the presence of NaH2PO2, BTTA forms a five-membered cyclic anhydride on cotton at temperatures as low as 120°C. However, no esterification takes place on the fabric at such temperatures. The data also indicate that NaH2PO2reacts with the anhydride intermediate when the temperature rises above 180°C. We have found that esterification of cotton cellulose by BTTA takes place only when NaH2PO2is present and the temperature is above 180°C. Therefore, the catalysis effects of NaH2PO2for cotton esterification by BTTA are probably related to the reaction between NaH2PO2and the anhydride intermediate.

Multifunctional carboxylic acids have been used as nonformaldehyde durable press finishing agents for cotton. In previous research we found that maleic acid (MA) and itaconic acid (IA) polymerize in situ on cotton fabric at elevated temperatures when both potassium persulfate (K2S2O8) and sodium hypophosphite (NaH2PO2) are present, thus imparting wrinkle resistance to the treated cotton fabric. We also found that MA and IA polymerize in aqueous solutions in the presence of K2S2O8 and NaH2PO2. In this research, we compared the effectiveness of poly(itaconic acid) (PIA) applied to cotton fabric as a polymer and IA applied as a monomer and allowed to polymerize in situ for crosslinking cotton cellulose. We found that IA is more effective in esterifying cotton cellulose and imparting a high level of wrinkle resistance to the fabric as it polymerizes in situ than PIA applied as a polymer. We also found that tensile strength loss of the cotton fabric crosslinked by IA polymerizing in situ as a function of fabric wrinkle recovery angle is practically the same as that crosslinked by PIA applied as a polymer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 319–326, 2001

Durable press finishing processes are commonly used in the textile industry to produce wrinkle-free cotton fabrics by crosslinking cotton cellulose. The most common crosslink ing agents are formaldehyde-based N-methylol reagents, such as dimethyloldihydroxyl ethyleneurea (DMDHEU). In recent years, multifunctional carboxylic acids have been employed as nonformaldehyde durable press finishing agents. In this research, we use a multiple angle laser light scattering photometer to measure the change in cellulose molecular weight as a result of cotton cellulose depolymerization caused by a polycar boxylic acid, a Lewis acid used as a catalyst for DMDHEU, or their combination. Cellulose depolymerization takes place on the fabric treated with a polycarboxylic acid or a Lewis acid. The combination of Lewis and polycarboxylic acids as an "activated" catalyst for DMDHEU causes more severe cellulose depolymerization. Our results indicate a direct correlation between tensile strength loss of the treated cotton and the molecular weight of cellulose.

Polycarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid (BTCA) have been the most promising nonformaldehyde durable press finishing agents to replace the traditional N-methylol reagents. High levels of smooth fabric appearance are the direct result of ester crosslinking of cotton cellulose by a polycarboxylic acid, and appearance is therefore determined by the amount of ester crosslinks formed on the fabric. In this research, we use acid-base titration to evaluate ester crosslinking by measuring the concentrations of the ester and the free carboxylic acid and the percent of carboxyl groups forming crosslinks on the cotton treated with BTCA. We correlate the wrinkle resistance of the treated cotton with the ester concentration on the fabric. The linear correlation between wrinkle-recovery angle and ester concentration indicates that ester concentration determined by titration can be used as the basis for evaluating the effectiveness of crosslinking for durable press finished cottons.

Neither maleic acid (MA) nor itaconic acid (ITA) polymerize under conditions normally used for vinyl monomers. The literature reports that treating cotton fabric with a mixture of MA and ITA significantly improves its wrinkle resistance. In our previous research, we used FRIR spectroscopy to study cotton fabric treated with ITA and MA, and found that free radical polymerization of MA and ITA takes place on cotton at elevated temperatures when both potassium persulfate and sodium hypophosphite are present. In this research, we remove the copolymer of MA and ITA from the treated cotton with alkaline hydrolysis, and apply time-of-flight (TOF) mass spectroscopy with matrix-assisted laser desorption/ioniza tion (MALDI) and a multiple angle laser light scattering (MALLS) photometer to determine the molecular weight and molecular weight distribution of the copolymer. The MALDI/TOF mass spectroscopy and MALLS data confirm that in-situ copolymerization of MA and ITA takes place on the cotton. The molecular weight of the copolymer is in the approximate range of 2000-3000.

In recent years, extensive efforts have been made to find nonformaldehyde durable press finishes to replace the traditional formaldehyde-based reagents. In this research, glutaraldehyde is evaluated as a nonformaldehyde durable press finish for cotton fabrics. The infrared spectroscopy data show that the two aldehyde groups of glutaraldehyde react with cotton at elevated temperatures. There is a linear correlation between the fabric wrinkle recovery angle and the reduction in the carbonyl band intensity of the treated cotton cured at increasing temperatures. We have compared glutaraldehyde with low- formaldehyde DMDHEU and nonformaldehyde DHDMI as crosslinking agents for cotton. The fabric finished with glutaraldehyde shows adequate wrinkle resistance, sufficient white ness, and high strength retention. As a nonformaldehyde durable press finishing agent, the performance of glutaraldehyde is superior to that of DHDMI.

In our previous research, we investigated the strength loss of durable press cotton fabric caused by acid-catalyzed depolymenzation. In this paper, we study the relationship between the tensile strength loss of crosslinked cotton fabric and the molecular structures of the crosslinking agents. We use 1,2,3,4-butanetetracarboxylic acid (BTCA) and all-cis-1,2,3,4- petanetetracarboxylic acid (CPTA), linear and cyclic terrafunctional carboxylic acids, respec tively, to treat cotton at different concentrations and different temperatures. We find that BTCA is more effective and imparts higher levels of wrinkle resistance than CPTA, but the relationship between tensile strength loss and wrinkle recovery angle (WRA) for the treated fabric is independent of the differences in their molecular structures and reactivity. We also compare the tensile strength loss of cotton fabric treated with DMDHEU and 1,3-dimethyl-4,5-dihydroxyl ethyleneurea (DHDMI) and observe a similar phenomenon.

Polycarboxylic acids have been used as crosslinking agents for cotton fabrics and paper to replace the traditional formaldehyde-based reagents. Previously, we found that a polycarboxylic acid esterifies cotton cellulose through the formation of a five-membered cyclic anhydride intermediate. Both maleic acid (MA) and itaconic acid (ITA) are extremely difficult to polymerize under conditions normally used for free radical polymerization. It has been reported in the literature that treatment of cotton fabric with a mixture of MA and ITA significantly improved wrinkle-resistance of the fabric. In this research, we investigated the in situ copolymerization of MA and ITA on cotton fabric. Fourier transform-infrared spectroscopy was used to study the anhydride carbonyl formed on the cotton fabric treated with the mixtures of MA and ITA. A redox titration technique also was applied to determine the quantity of alkene double bonds on the treated fabric. It was found that free radical copolymerization of MA and ITA does not occur on the fabric at elevated temperatures when potassium persulfate is present as an initiator. It does occur, however, when both potassium persulfate and sodium hypophosphite are present on the fabric. The in situ copolymerization on the cotton fabric probably is initiated by a reduction–oxidation system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 327–336, 2000

In recent years, extensive efforts have been made to find formaldehyde-free durable press finishes to replace the traditional formaldehyde-based N-methylol compounds. 1,2,3,4-Butane-tetracarboxylic acid (BTCA) has been the most efficient nonformaldehyde crosslinking agent for cotton, with sodium hypophosphite (NaH2PO2) being the most effective catalyst. In our previous research, we found that a polycarboxylic acid esterifies cellulose through the formation of a five-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups. In this research, we use Fourier transform infrared spectroscopy (FTIR) to study the formation of cyclic anhydride intermediates by BTCA and poly(maleic acid) (PMA) with and without the presence of NaH2PO2. In the absence of NaH2PO2, BTCA forms the cyclic anhydride only when the temperature reaches the vicinity of its melting point. In the presence of NaH2PO2, however, the anhydride forms at much lower temperatures. We have found that NaH2PO2weakens the hydrogen bonding between the carboxylic acid groups of BTCA, contributing to accelerated anhy dride formation at lower temperatures. Sodium hypophosphite also accelerates the for mation of the anhydride intermediates by polycarboxylic acids in an amorphous state. The FTIR spectroscopy data show that there is a chemical reaction between the anhydride intermediate and NaH2PO2when the temperature climbs above 200°C.

Polycarboxylic acids have been used as crosslinking agents for cellulosic materials to replace traditional formaldehyde-based reagents. The literature reports that maleic acid (MA) and itaconic acid (ITA) can copolymerize on cotton fabric in the presence of potassium persulfate, and esterification of cotton by the copolymer imparts wrinkle resistance to the treated cotton fabric. Our previous research found that in-situ copoly merization occurs only when both potassium persulfate and sodium hypophosphite are present on the cotton fabric. In this work, we investigate in-situ homopolymerization of maleic acid and itaconic acid on cotton fabric. We use Fourier transform infrared spectroscopy to study the anhydride carbonyls formed on the cotton treated with MA and ITA. We also use a redox titration technique to determine the quantity of the remaining monomers on the treated fabric. The data indicate that MA and ITA can polymerize on the fabric at elevated temperatures when potassium persulfate is present at concentration levels higher than reported previously. This conclusion is confirmed by the performance of the cotton treated with MA and ITA in the presence of potassium persulfate at different concentration levels.

Citric acid (CA), one of the polycarboxylic acids used as crosslinking agents for cotton, is cost-effective and environmentally friendly, but its tendency to discolor fabric is a major disadvantage for white fabrics. In this research, we investigate cotton fabric yellowing caused by citric acid at elevated temperatures. We find that yellowing increases as curing temperature, curing time, and CA concentration increase. Using sodium hypophosphite as a catalyst causes less fabric yellowing than monosodium phosphate. The wet analysis data demonstrate that an alkene double bond is formed on cotton fabric treated with CA under curing conditions. Nuclear magnetic resonance (NMR) data indicate that CA is partially converted to trans-and cis-aconitic acids on cotton through dehydration. The visible spectra of fabric treated with trans-and cis-aconitic acids and cured at elevated temper atures show strong absorption in the 400-550 nm region. For polymeric multifunctional carboxylic acids, an increased number of hydroxyl groups in their molecules increases fabric yellowing. Therefore, yellowing caused by citric acid and other hydroxyl multi functional carboxylic acids can probably be attributed to the formation of unsaturated polycarboxylic acids.

Durable press finishing processes are commonly used in the textile industry to pro duce wrinkle-free cotton fabrics and garments. Crosslinking cellulose increases wrinkle resistance and reduces the mechanical strength of treated cotton fabric. Wrinkle recov ery angle (WRA) and tensile strength are the two most important parameters frequently used for evaluating the performance of crosslinked cottons. In this study, we investigate the correlation between WRA and tensile strength, and determine the amount of cross linking agent bonded to the cotton using FRIR spectroscopy. The crosslinking agents include dimethyloldihydroxylethyleneurea, 1,2,3,4-butanetetracarboxylic acid, and glutaraldehyde. We develop linear regression models to investigate the relationship between the WRA and tensile strength of the treated cotton and the carbonyl band absorbance in the infrared spectra. The data indicate that FTIR spectroscopy is a reliable technique for predicting the performance of durable press finished cotton fabrics when calibration standards are established.

Butanetetracarboxylic acid (BTCA) has been used as the most effective nonformaldehyde crosslinking agent for cotton and wood pulp cellulose. Our previous research has indicated that a polycarboxylic acid esterifies cellulose in two steps: the formation of a five-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups, and the reaction between cellulose and the anhydride intermediate to form an ester linkage. In this research, we investigated the formation of carboxylic anhydrides by BTCA and other polycarboxylic acids in powder forms, and as finishes applied to cotton fabric using thermal gravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. We found that BTCA and other polycarboxylic acids in powder forms start to form five-membered cyclic carboxylic anhydrides when the temperature reaches the vicinity of their melting points. The formation of carboxylic anhydride is accelerated above the melting points. We also found that BTCA forms anhydrides at lower temperatures when it is applied to cotton fabric as a finish. An increase in temperature increases both the amount of anhydride and the amount of ester formed on the cotton fabric. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2711–2718, 1998

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.

Polycarboxylic acids are being developed as new nonformaldehyde crosslinking agents for cotton fabrics to replace the traditional N-methylol reagents. In this research, the mechanism of esterification between polycarboxylic acids and cotton cellulose was elucidated using FT-IR spectroscopy. All the infrared spectroscopic data support the hypothesis that cyclic anhydrides are formed as intermediates, which in turn esterify with cotton cellulose. The infrared spectroscopic data also demonstrate that cyclic anhydrides are very reactive and are able to esterify with cotton cellulose without a catalyst present and at a temperature much lower than the curing temperatures used for polycarboxylic acids. Therefore, the chief role of catalysts such as sodium hypo phosphite is that they accelerate the formation of a cyclic anhydride from a polycar boxylic acid.

Polycarboxylic acids are being developed as new nonformaldehyde finishes for cotton fabrics to replace the traditional dimethyloldihydroxylethyleneurea. In this research, Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) was used to char acterize the intermolecular ester crosslinkages in cotton cellulose. When esterification occurs between a polycarboxylic acid and cotton cellulose, the carbonyls retained in the cotton exist in three forms: ester, carboxylic acid, and carboxylate anion. The FT- IR data show that the band of the ester carbonyl can be separated from the bands of the other two carbonyls; therefore, the ester crosslinkages of the finished cotton fabrics can be compared on a semiquantitative basis with FT-IR spectroscopy. FT-IR/PAS was used to study the hydrolysis of the ester linkages, the recurability of the finished cotton fabrics, and the distribution of ester crosslinkages between the surfaces of the cotton fabrics and their interiors.

Cotton fabrics were treated with dimethyloldihydroxyethyleneurea (DMDHEU) and methylated DMDHEU using conventional padding and a foam finishing tech nique. The finished fabrics were studied using Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS). Both finishing agents appeared to have a more homo geneous distribution in the foam finished fabrics than in the conventionally finished fabrics. This probably explains the observation that wrinkle recovery angle was generally higher for foam finished fabrics than for conventionally finished fabrics, since a more homogeneous distribution of the finishing agents allows more cotton cellulose to be crosslinked throughout the fabrics.

When the three sodium salts of phosphoric acid were used as catalysts for the ester crosslinking of cotton cellulose, they showed different levels of effectiveness due to the different pH values of the finish baths. In this research, the effect of finish bath pH on the esterification of cotton cellulose by 1,2,3,4-butanetetracarboxylic acid (BTCA) was investigated using Fourier transform infrared spectroscopy (FT-IR). FT- IR data indicated that the esterification by polycarboxylic acids is pH-dependent. When a cotton fabric was finished with BTCA without a catalyst, both the number of ester linkages formed in the fabric and the effectiveness of the bonded BTCA mol ecules first increased, then decreased as the pH of the finish bath increased from 1.5 to 5.5. An optimum pH range for esterification was determined. A similar phenomenon also occurred when a catalyst (phosphate or hypophosphite) was used. Therefore, it is necessary to choose the optimum pH range of a finish bath in order to achieve the most effective esterification.

Esterification of cotton cellulose by a polycarboxylic acid proceeds in two steps: the formation of a five-member cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups of the polycarboxylic acid, and the reaction between cellulose and that intermediate to form an ester. We studied the effect of finish bath pH on anhydride intermediate formation using Fourier transform infrared spectroscopy. Our previous research demonstrated that esterification of cellulose by a polycarboxylic acid was not acid-catalyzed. The infrared spectroscopy data presented here indicate that the amount of anhydride intermediate formed in a cotton fabric increases as the finish bath pH decreases from 4.5 to 1.5. Therefore, the formation of the cyclic anhydride intermediate is accelerated by an increase in proton concentration of the finish bath. Anhydride intermediate formation and cellulose esterification show different pH-de pendencies.

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) was used to investigate the effects of ultraviolet (UV) radiation on cotton cellulose. The infrared spectroscopic data revealed that carboxylic acid was the main photo-oxidation product. It was also concluded that UV radiation was able to penetrate through the cotton fabric and caused oxidation in the bulk of the fabric. However, the highest degree of oxidation occurred in the near-surface of the fabric facing the UV radiation.

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has been applied as a near-surface analysis technique for various types of samples. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) also was reported for characterizing surface species of fibrous materials. In this research, chemically modified textile fabrics, fibers, and films were studied by both FT-IR/PAS and DRIFT. The capability of near-surface analysis for both techniques was evaluated and compared. Even though diffuse reflectance infrared spectra show an enhancement in the band intensity of near-surface species, FT-IR/PAS appears to have a much smaller sampling depth than DRIFTS. All the data demonstrate that FT-IR/PAS is a useful near-surface analysis technique for polymeric fibers and films.

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) and x-ray photoelectron spectroscopy (XPS) were used to determine the location of a copolymeric finish in poly(ethylene terephthalate) (PET) fibers. The XPS studies showed that the copolymeric finish was deposited on the fiber surfaces. The FT-IR/PAS data demonstrated possible penetration of the finish from the fiber's surface into the near-surface. The combination of FT-IR/PAS and XPS appears to be very useful for the determination of finish location in chemically modified fibers.

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.

The photooxidation of a nonwoven polyethylene fabric was investigated using Fourier transform infrared photoacoustic spectroscopy. The infrared spectroscopic data indicated that hydroperoxide, alcohol, aldehyde, ketone, carboxylic acid, and anhydride groups were formed as the products of the photooxidation of the polyethylene fabric and that the relative amount of carboxyl among all carbonyls increased as the photooxidation progressed. The distribution of the photooxidation products was inhomogeneous between the two surfaces of the fabric. The highest degree of photooxidation occurred on the surface of the fabric facing the UV radiation source, whereas the lowest degree of photooxidation was on the back surface of the fabric. We also found that the polyethylene nonwoven fabric showed a slower photooxidation rate than the polypropylene nonwoven fabric. The UV radiation at 254 nm caused photooxidation of polyethylene. No photooxidation was observed in the fabric exposed to the UV radiation at 350 nm under the same conditions.

Polycarboxylic acids have been used as nonformaldehyde crosslinking agents for cotton fabrics to replace the traditional N-methylol reagents. In this research, we compared 1,2,3,4-butanetetracarboxylic acid (BTCA) with poly(maleic acid) (PMA) as crosslinking agents for cotton cellulose. BTCA and PMA have similar molecular structures with carboxyl groups bonded to their molecular backbones, and both form five-membered cyclic anhydride intermediates during a curing process. However, BTCA is a more effective crosslinking agent for cotton cellulose than PMA. This is mainly attributed to the differences in the mobility of the anhydride intermediates to access the cellulosic hydroxyl groups during a curing process. The mobility of the anhydride intermediate of PMA is reduced due to its molecular size and multiple bonding between a PMA molecule and cellulose. Consequently, more anhydride and less ester are detected on the cotton fabric treated with PMA than on the fabric treated with BTCA. The amount of the unreacted anhydride intermediate on the fabric treated with PMA is reduced whereas the amount of ester is increased when another hydroxyl-containing compound of low molecular weight is present. Thus, the infrared spectroscopy data show a clear link between the molecular weight of a polycarboxylic acid and its effectiveness for crosslinking cotton cellulose. © 1997 John Wiley & Sons, Inc.

In our previous research, we investigated the use of two polymers of maleic acid, i.e.,the homopolymer (PMA) and the terpolymer (TPMA), for crosslinking cotton cellulose. We found that PMA and TPMA were less effective than 1,2,3,4-butanetetracarboxylic acid (BTCA) due to the low mobility of the anhydride intermediates to access the cellulosic hydroxyl during a curing process. We found that the hydroxyl of citric acid (CA) hinders its esterification with cotton cellulose, and so is less effective than 1,2,3-propanetricar boxylic acid as a crosslinking agent for cotton. We also found that CA esterifies the anhydride intermediate of PMA or TPMA on the cotton fabric formed under curing con ditions. In this research, we observed a synergistic effect by combining PMA or TPMA with CA as co-crosslinking agents for cotton fabrics. The combination of TPMA/CA is more effective than the PMA/CA combination for imparting wrinkle resistance to the finished cotton fabrics. Cottons finished with the TPMA/CA combination show superior durable press performance, good laundering durability, and high fabric strength retention. The superior performance and cost effectiveness of this new finishing system makes it feasible as a replacement for formaldehyde-based durable press finishes.

Multifunctional polycarboxylic acids have been used as nonformaldehyde cross linking agents for cotton fabrics to replace the traditional N-methylol reagents. Ester ification of cotton cellulose by seventeen aliphatic and aromatic polycarboxylic acids is studied using Fourier transform infrared spectroscopy. Five-membered cyclic an hydride intermediates formed under the curing conditions are identified on cotton fabrics treated with these acids. Only those polycarboxylic acids that form cyclic an hydride intermediates esterify cotton cellulose. Formation of the cyclic anhydride intermediates and esterification of cotton cellulose take place in the same curing tem perature regions. The infrared spectroscopy data also indicate that the second carboxyl group in a bifunctional carboxylic acid is not able to esterify cotton cellulose effectively. Therefore, we can conclude that a polycarboxylic acid esterifies cotton cellulose through the formation of a cyclic anhydride intermediate. The infrared spectroscopy data also reveal that 1,2,3,4-butanetetracarboxylic acid is the most effective crosslinking agent for cotton cellulose among the acids studied.

Butanetetracarboxylic acid (BTCA) has been a promising nonformaldehyde durable press finish for cotton fabrics to replace N-methyol reagents. Acid-base titration and Fourier transform infrared (FT-IR) spectroscopy are applied as quantitative analytical techniques to determine the amount of BTCA applied to cotton fabric and the amount of ester formed on the fabric after a curing process. Acid-base equilibria of BTCA are discussed. We find that FT-IR spectroscopy is a reliable quantitative analytical technique for quantifying BTCA and its ester on cotton fabric when the calibration standards are established by acid-base titration. Calibration curves and regression equations are pre sented. To determine the amount of ester formed on the finished cotton fabric using FT-IR spectroscopy, it is necessary to use a sodium hydroxide solution to quantitatively convert carboxyl to carboxylate. The acid-base equilibria associated with this procedure are also discussed.