Joseph S. Bruno

Application of Mechanisms for Wet and Dry Wrinkle Recovery to Fabric Exhibiting the Unusual Combination of High Dry and Low Wet Recovery

By use of polyethyleneglycols and cross-linking agents in a conventional pad-dry-cure process, fabrics have been produced with the unusual combination of high dry wrinkle and low wet wrinkle recovery. These fabrics and others with the various combinations of dry and wet wrinkle recovery have been examined in terms of the mechanisms for dry and wet wrinkle recovery. On the basis of certain textile properties, an explanation is offered for this unusual combination of high dry and low wet recovery.

Moisture-Related Properties of Cotton-Polyester Blend Fabrics1

The moisture-related properties of a series of cotton-polyester blend broadcloths and sheetings were investigated. The composition of the broadcloth ranged from all-cotton to 68% polyester and 32% cotton, and the sheeting varied from all-cotton to 50% polyester and 50% cotton. The moisture properties measured were drop absorbency, wicking time, moisture regain, vapor transport, liquid transport, and total absorbency. The fabrics were tested untreated and finished with various durable-press treatments. Chemical additives either decreased or increased a number of measured moisture properties, some of which might be related to comfort.

Thermally Active Fabrics Containing Polyethylene Glycols

Polyethylene glycols (PEG) of low molecular weight (300-1,000) can be durably bound to cotton, cotton-polyester blends, and most commercially available fabrics (such as wool, acrylic and nylon) by a pad-dry-cure method utilizing a polyfunc tional crosslinking agent. The extent to which the PEGs react with and are bonded to the fabrics is dependent on the molecular weight of the polymer, the type and con centration of the crosslinking agent and the catalyst. The resultant fabrics release heat when the temperature drops and absorb heat when the temperature rises. The ther mal activity and the temperature at which the modified fabrics are thermally active are dependent on the molecular weight of the polyol and on the type and concentra tion of crosslinking agent and catalyst, but appear to be relatively independent of fiber type. Thermal storage and release properties were calculated and evaluated by differential scanning calorimetry, and were reproducible after ten heating and cooling cycles and after five machine launderings. Other textile properties such as soil release, antistatic behavior and water absorbancy appear to be beneficially affected.

The Crosslinking of Blended Fabrics

The application of a crosslinking agent (DMDHEU) to all-cotton and to polyester-cotton blended fabrics indicated that similar add-ons were observed with the various fabrics. By means of special blended fabrics, it was indicated that most of the reaction occurs with the cotton fibers. Thus, there may be some tendency to overcrosslink the cotton fibers in blended fabrics if conventional finishes for cotton are applied full strength on blended fabrics By use of other special blends of cotton and polyester, potential hazards in finishing blended fabrics were illustrated.

The Alkali-Catalyzed Reaction of Methylol Carbamates with Cotton

The alkali-catalyzed reaction of dimethylol monoalkyl carbamates with cotton cellulose proceeds through only one of the N-methylol groups and produces no cross linking. This results from à different reactivity in the second methylol group, after the first has reacted. The reaction produces a cotton containing amido hydrogens whose number or properties vary with the alkyl group of the carbamate.

Improving the Process for Treating Cotton Fabrics with Crosslinked Polyols

Addition of NaCl to pad bath solutions contaimng polyethylene gly col (50% PEG-1,000), crosslinking resm (11% DMDHEU) and mixed acid catalysts (3.3% MgCl2 · 6H 2O/citric acid) substantially mcreased the add-on of 100% cotton fabrics (compared to fabrics treated with solutions without salt) when they were dried and cured. Fabrics comprised of synthetic fibers (e.g., polypropylene) and cot ton blend fabrics containing 50% or more of synthetic fibers had only slightly higher weight gains when salt was in the pad bath solution. Concentrations of added NaCl were varied from 1 to 10% by weight and molar ratios of mixed acid catalysts were varied from 10/1 to 1/1 (MgCl2 · 6H2O/citric acid). Concentrations of added NaCl and mixed catalyst ratios to obtain highest weight gams in the cotton fabrics were 5% and 5/1, respectively. Higher weight gains for cellulosic fabrics are attributed to reduction in penetration of the DMDHEU into the fiber due to an increase in the viscosity of the polyol solutions when NaCl is present, thus permitting optimum reaction of resin with the polyol at the fiber surface. The mode of action of the NaCl is also briefly discussed in relation to hypotheses that are consistent with fundamen tal polymer and physical chemistry.

Modifying the Electrical Resistivity of Durable-Press Fabric

The influence of crosslinking on the resistivity of cotton and cotton-polyester fabrics is reported. Chemical finishes, including the use of hydrophilic grafts and swelling crosslinking treatments, were employed to produce durable-press fabrics with resistivity close to that of the untreated fabrics. Such fabrics should have improved static characteristics.