Quantitative water uptake study in thin nylon-6 films with NMR imaging

Nylon-6 is widely used as an engineering plastic. Compared to other synthetic polymers, nylon-6 absorps significant amounts of water. Although the typical sorbed amounts and diffusivity of water are well-known, less is known about the relation between the diffusivity and the water content. Attempts have been made in the past to obtain such relationship from moisture content profiles as measured with NMR imaging. However, these studies were mainly performed at high temperatures and without a proper calibration of the signal. In particular, at room temperature, far below the Tg of dry nylon, plasticizing effects of water will result in a strong contribution of the polymer signal. Therefore, we have studied water uptake in 200 µm nylon-6 films in this temperature range near room temperature with NMR imaging. By calibrating the NMR signal with vapor sorption data, we were able to obtain moisture content profiles. A strongly nonlinear relation between the NMR signal and the moisture was observed at room temperature, which proves that contribution of the polymer to the NMR signal can neither be neglected nor assumed to be constant in time. Furthermore, glass transition temperature measurements combined with the water distribution provide plasticization profiles during water uptake. On the basis of the moisture content profiles, the moisture content dependency of the diffusion coefficient for water uptake is deduced through a Matano-Boltzmann analysis. This relation appeared to be highly nonlinear at room temperature. The self-diffusion coefficient was calculated through combination of the sorption-isotherm and the diffusion coefficient. Exposure of a nylon film to heavy water showed that water affects only a small fraction of the amorphous nylon phase. Water transport most likely occurs in this fraction of the amorphous phase. It is concluded that the heterogeneity of the amorphous phase is an important issue for a profound understanding of water transport in nylon-6 films

The role of basic psychological needs satisfaction in the relationship between transformational leadership and innovative work behavior

The aim of this contribution was to investigate predictors of innovative work behavior (IWB) in nonprofit organizations. For instance, in schools, innovative solutions are crucial as the quality of education and therefore the schools' competitiveness depends on their ability to keep pace with technological, economic, and societal transformations. We addressed this issue in a quantitative study with 130 teachers in Dutch secondary schools employing a time-lag design. In accordance with self-determination theory, we investigated the role of transformational leadership for enhancing IWB and the role of basic psychological needs satisfaction in mediating this relationship. By employing structural equation modeling, we found that transformational leadership was positively related to the satisfaction of the teachers' needs for autonomy and competence. Furthermore, the satisfaction of the need for competence positively predicted teachers' IWB. In addition, perceived competence fully mediated the relationship between transformational leadership and teachers' IWB. Accordingly, persons with leadership responsibilities should adopt a transformational leadership style and motivate their employees by providing individual attention, intellectual stimulation, and encouragement for goal striving. Specifically, leaders may provide feedback on employees' innovative ideas and their strategies for realizing innovative solutions, thus helping them to become increasingly confident about what they can achieve and improve concerning their contributions to innovation development. For human resource development (HRD) professionals, our findings imply that efforts toward leadership training and development (e.g., training, coaching, and mentoring) should incorporate knowledge and practical experiences about transformational leadership as well as its role for employees' IWB and their contributions to organizational and professional development