Brenda J. Trask-Morrell

Thermoanalytical Ranking of Catalysts for Use with Polycarboxylic Acids as Durable Press Reactants1

Thermoanalytical (TA) techniques were used to analyze several polycarboxylic acids (PCA) in the presence of each of three inorganic salts of phosphorus-containing acids used as catalysts—disodium phosphate, monosodium phosphate, and sodium hypo-phosphite. The influence of catalyst was measurable in differential scanning calorimetric and thermogravimetric analyses. Previously, TA data gathered on PCAs alone indicated that the acids that performed best in fabric trials produced large residues, low rates of weight loss/minute, and high total heats of reaction in J/g. Adding a catalyst to an acid increased residues and decreased rates even further. Total heat values decreased slightly in the presence of the catalyst. A mathematical transformation incorporating the three TA parameters into a single predictor factor was used to rank catalysts and predict which catalyst was best for each of four acids of interest to textile chemists. When this TA factor was compared with another factor derived from fabric durable press and strength data, the rankings agreed.

Thermoanalytical Study of Durable Press Reactant Levels on Cotton Fabrics Part I: Nonformaldehyde Polycarboxylic Acids

A current goal of our research is to identify unknown durable press (DP) finishes on cotton fabrics using only thermal analytical techniques. In pursuit of this goal, we have treated 100% cotton printcloth with five low- and nonformaldehyde finishes at four to six treatment levels. Two polycarboxylic acids—citric and butanetetracarbox ylic—were used with sodium hypophosphite catalyst to produce nonformaldehyde fabric finishes. Three formaldehyde-based finishes were produced with 1,3-dimethylol- 4,5-dihydroxyethyleneurea. Results of differential scanning calorimetric and ther mogravimetric analyses were compared with those of untreated and catalyst-treated controls. The thermal parameters tested to recognize reactants included amount of residue, maximum rates of weight loss, peak temperatures, and peak areas, along with various parameter ratios. There were progressive changes in all fabric thermograms as agent/catalyst levels increased. Even at the 2% agent level, we could detect that fabric had been treated. It was also not difficult to distinguish between the low- and nonformaldehyde DP finishes. Thermal profiles of catalyst controls indicated that the catalyst was a substantial contributor to thermal parameters. This study has brought fabric finish identification using thermal analyses much closer to reality.

Thermoanalytical Study of Durable Press Reactant Levels on Cotton Fabrics Part II: Finishes Based on DMDHEU

Cotton printcloth has been treated with five low- and nonformaldehyde finishes at multiple treatment levels. In Part I, two polycarboxylic acids, butanetetracarboxylic and citric, catalyzed with sodium hypophosphite produced the nonformaldehyde fabric finishes. Three formaldehyde-based finishes have been produced with 1,3-dimethylol- 4,5-dihydroxyethyleneurea (DMDHEU) catalyzed with magnesium chloride / citric acid and are the subject of Part II. Differential scanning calorimetric and thermogravimetric analyses are performed and the results compared with those of untreated and treated controls. Thermal parameters and various parameter ratios are analyzed for progressive changes as agent / catalyst levels increase. Thermal profiles of catalyst controls indicate that the catalyst is a substantial contributor to thermal parameters. We can distinguish between the low and nonformaldehyde DP finishes, between the three DMDHEU-based finishes, and between the four finish levels. Finish level is the most difficult. Three- dimensional comparison graphs of three parameters chosen by means of stepwise discriminate analyses allow finish level assessments to within 2%. The preponderance of evidence after parameter-by-parameter comparisons correctly assigns finish level. A current goal of our research is to identify unknown durable press finishes on cotton fabrics using only thermal analytical techniques. Quality control applications relative to finish and finish level are clearly possible at this time. This study has brought us much closer to realizing our primary goal of finish identification using only ther moanalytical procedures.

Effect of Catalysts on the Thermal Characteristics of Cotton Citric Acid DP Finishes

Citric acid-based durable press finishes catalyzed with various levels of sodium hypophosphite, sodium phosphate, or sodium phosphite have been studied systematically. Thermal characteristics are compared, beginning with visual examination of the thermograms and quantitation of multiple parameters primarily from thermogravimetric analyses, and combinations of parameters are examined in three-dimensional graphs. Such combinations are successfully used to distinguish between finishes and assess finish levels. Comparisons of samples from this series with those of previous studies show that each sample is unique. Finish identification depends critically on the catalyst used, and therefore these citric acid finishes can be recognized as different from finishes based on 1,3-dimethylol 4,5-dihydroxyethyleneurea (dmdheu) and magnesium chloride/citric acid catalyst. Successful identification of specimens using only thermoanalytical techniques is an indication that quality control in textile mills is feasible with these procedures.

Thermoanalytical and FT-IR Characteristics of Fabrics Finished with BTCA / Chloroacetates Part II: FT-IR Identification of Volatile Decomposition Products

Cotton fabrics esterified with polycarboxylic acids possess excellent smooth drying properties and have good strength retention. The best results have been obtained with catalysts of inorganic phosphorus acids, especially sodium hypophosphite monohydrate (SHP). However, because SHP is fairly expensive and there is some concern that phos phorus from finishing plants would contribute to the pollution of rivers and streams, other catalyst systems are under investigation as substitutes. This paper reports on the characterization of sodium salts of chloroacetic acids as catalysts for esterification crosslink finishing of cotton with 1,2,3,4-butanetetracarboxylic acid (BTCA). In this part of the study, we report on FT-IR identification of the volatile products formed on thermal decomposition of fabrics treated with BTCA and chloroacetate catalysts. HCl does not appear to be released at any temperature, and chloroform, which is a decom position product when trichloroacetate is used as the catalyst, is formed only above curing temperatures.

Thermoanalytical and FT-IR Characteristics of Fabrics Finished with BTCA/Chloroacetates Part I: DSC and TGA Results

Cotton durable press (DP) finishes of 1,2,3,4-butanetetracarboxylic acid (BTCA) catalyzed with sodium dichloroacetate, sodium monochloroacetate, or sodium acetate (SDCA, SMCA, or SA) were prepared at four acid / catalyst ratios, and catalyst controls were also treated. Thermal analyses were performed using differential scanning calo rimetric (DSC) and thermogravimetric (TG) techniques. Overlaid DSC or TG ther mograms indicated few visible instances of progressive changes produced with varying ratios of BTCA/catalyst. Differences in finishes were assessed when means and standard errors were tabulated. Characterization of this series involved either seventeen or five individual parameters, depending on whether the finish produced two or one weight loss region(s). Some thermal parameters, when plotted versus catalyst ratios of 1/ 0.5, 1/1, 1/1.5, and 1/2, produced a peak (or a minimum) instead of steadily in creasing, decreasing, or remaining level, as found in earlier studies. Finish identification of BTCA/SDCA was rapid; recognition of BTCA/SMCA or BTCA/SA was more compli cated. All BTcA/acetate catalyzed finishes were easily distinguished from BTCA/sodium hypophosphite finished fabrics or 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) finishes. Most distinguishing thermal features are related to catalyst. Part II discusses TGA/FT-IR studies of BTCA/acetate catalyzed samples.

Influence of Prolonged Storage on Formaldehyde Liberation from Durable Press Textiles1

Liberated formaldehyde from durable press cotton textiles has been found to originate from several sources within a finish. Different formaldehyde sources release differing degrees of formaldehyde. Changes in formaldehyde release (AATCC-112 Test), steady-state (or residual) formaldehyde, and formaldehyde transport levels in both washed and unwashed finished fabrics during ambient storage were compared for several finishes. Three dimethyloldihydroxyethyleneurea-based finishes and a dimethylolethyleneurea-based finish were used in the study with two magnesium chloride-based catalysts. Contributions from the finishing parameters were emphasized in the response to ambient storage under confined and unconfined conditions.