No abstract

SYNOPSISTwo new methods for determining Hansen's three-dimensional solubility parameters (3DSP) for lightly crosslinked polymers are presented and evaluated using commercial glove materials composed of butyl, natural, nitrile, and neoprene rubber. In the first method, the polymer 3DSPs are determined from a weighted average of the 3DSPs of a range of organic solvents, where the weighting factor is the product of the solvent molar volume and the fractional uptake of the solvent measured by immersion testing. The resultant polymer 3DSPs were used to model solvent uptake via the Hildebrand-Scott and modified FloryRehner expressions for the Flory interaction parameter. After grouping solvents of similar structure and applying an additional weighting factor, estimates of equilibrium solubility within a factor of two of experimental values were obtained for 176 of the 212 (83%) solvent-polymer combinations examined. In the second method of estimating polymer 3DSPs, the Flory interaction parameters for all solvent-polymer pairs are determined at the outset via the modified Flory-Rehner equation and used to solve for the polymer 3DSP values by multiple nonlinear regression. Solubility estimates are then back-calculated. This method provided different values of the 3DSPs for the polymers, including negative 6 , values for the butyl and natural rubber. However, the accuracy of solubility estimation was comparable to that obtained using the weighted-average method without the need for any adjustable factors. The advantages of these alternative methods over the graphical method for obtaining reliable estimates of the 3DSPs of lightly crosslinked polymers are discussed. This is the first demonstration of a general 3DSP-based approach to quantitative solubility modeling in polymer-solvent systems.

SYNOPSISThe most widely accepted method for determining Hansen's three-dimensional solubility parameters (3DSP) for crosslinked polymers entails graphically estimating the center of a spherical region in SDSP-coordinate space whose boundaries are defined in terms of the extent of swelling by solvents whose 3DSP values are known. In this article, the results of immersion tests performed a t 25OC with 53 solvents on each of four commercial polymeric glove materials are used to critically evaluate this method. Analyses reveal a number of serious shortcomings with respect to the reliability of 3DSP estimates obtained. In the context of modeling solubility or other measures of solvent-polymer compatability, it is recommended that alternative methods be sought for determining 3DSPs for crosslinked polymers.

Within the workplace, there is less reliance on engineering controls for dermal exposure protection and more reliance on the worker's motivation and training in use of personal protective equipment. Behavior thus becomes a significant determinant of dermal exposure, and its assessment paramount in examining and understanding factors influencing exposure. The main objectives of this study were to: (i) assess worker knowledge, attitudes, and perceptions (KAP) of workplace dermal hazards using a self-complete questionnaire and to examine KAP associations with behavior and exposure; (ii) compare worker and manager scores to identify potential gaps in KAP between the two groups; (iii) utilize a semiquantitative observational DeRmal Exposure Assessment Methodology (DREAM) to evaluate worker dermal exposure; and (iv) identify potential behavioral factors underlying exposure using DREAM and KAP. Nineteen industries across the Baltimore, Md. and Lancaster, Pa., regions participated in the study including a total of 89 workers and 17 managers. The scales within the KAP questionnaire that served as the outcome measure included knowledge, training, behavior, behavior beliefs, information beliefs, self-efficacy, and overall beliefs. DREAM scores ranged from 0.15 to 545 with a median of 8 and a mean (SD) of 22 (62.5). Whereas worker self-efficacy with respect to PPE use, and the group "workers with 10-20 years of experience" were marginally positively associated with protective behavior (p < 0.08 and p < 0.06, respectively), a question related to barriers to PPE use was negatively associated with precautionary behavior (p < 0.01). Dermal exposure was positively associated with workers in the age group 40-49 years as compared with those less than 40 years of age (OR = 4.86, 95% CI = 0.93, 25.62). There were no statistically significant associations between KAP and DREAM. This is one of the first studies to begin to elucidate worker knowledge, attitudes, and perceptions that underlie behaviors that lead to occupational dermal exposures. Results of the KAP questionnaire can inform strategies to improve awareness and protective practices in the workplace through factors such as increased worker dermal hazard knowledge, well-informed company PPE selection and availability, and improved worker training.

SYNOPSISThe most widely accepted method for determining Hansen's three-dimensional solubility parameters (3DSP) for crosslinked polymers entails graphically estimating the center of a spherical region in SDSP-coordinate space whose boundaries are defined in terms of the extent of swelling by solvents whose 3DSP values are known. In this article, the results of immersion tests performed a t 25OC with 53 solvents on each of four commercial polymeric glove materials are used to critically evaluate this method. Analyses reveal a number of serious shortcomings with respect to the reliability of 3DSP estimates obtained. In the context of modeling solubility or other measures of solvent-polymer compatability, it is recommended that alternative methods be sought for determining 3DSPs for crosslinked polymers.