David Karst

Care of PLA Textiles

The appropriate laundering conditions for the care of polylactide (PLA) textiles have been found. One problem with PLA is its poor resistance to hydrolysis and dramatic loss in strength at conditions typically used in textile processing such as alkaline conditions and elevated temperatures. In this study, PLA fabrics underwent 50 home laundering cycles at various pH levels (8 or 10), washing temperatures (35°C or 55°C), and drying conditions (line dry at 21°C/65% relative humidity or tumble dry at 50 or 70°C). After every 10 laundering cycle, the breaking tenacity, breaking elongation, and modulus of yarns in the PLA fabric were measured. It was found that washing PLA fabrics at pH 8 and 35°C and line drying it at 21°C and 65% relative humidity resulted in greater retention in mechanical properties than washing them at pH 10 and 55°C and tumble drying at 70°C. The authors therefore recommend the following care instructions for PLA textiles: use mild detergents with relatively low pH (pH 8), machine wash cold (35°C), and line dry. If machine drying is desired, tumble dry at the low heat setting or permanent press setting (50°C) is recommended.

Method for predicting sorption of small drug molecules onto polylactide

A method has been developed to predict the percent sorption of small drug molecules onto polylactide (PLA). In this method, molecular modeling is first used to calculate the interaction energy between the adsorbate and PLA. Alternatively, the adsorbate-PLA interaction energy can be calculated by summing the adsorbate functional group contributions to the interaction energy. These functional group contributions have been found in this study. The adsorbate-PLA interaction energy is then substituted into a linear equation to predict the natural log of the sorption equilibrium constant, and the percent sorption is obtained from this value. This linear equation has been developed based on experimental sorption data for dyes on PLA. The predicted percent sorption of two small drugs on PLA has been verified with experimental data. Our method possibly could be used to select appropriate drugs for use in controlled release studies involving PLA. This method also could be used to calculate the functional group contributions to the interaction energies between other drugs and polymers and to predict their percent sorption onto those polymers, which could be used to select drugs suitable for controlled release studies involving those polymers.

The Modeling of Liquor Flow in Textile Beam Dyeing

Abstract In fabric beam dyeing, it is difficult to apply the dye uniformly to the fabric because the fabric remains stationary while dye liquor is circulated through it. The uniformity of the liquor flow profile is critical to obtain uniform shade. This study used Computational Fluid Dynamics to determine how using metal collars and end-caps affect the liquor flow profile through the fabric during dyeing. This research found that placing the collars a distance of about 30% of the winding height under each side of the fabric gave the most uniform liquor flow profile of any collar position. In addition, the use of end-caps gave more uniform liquor flow than did the use of collars. A more uniform liquor flow profile would be expected to provide a more level dyeing.