Double glass transition in polyethylene naphthalate by MDSC, BDS, and TSDC.

In this work, we present an experimental study of the primary and secondary relaxations of the semi-crystalline polymer polyethylene naphthalate by modulated differential scanning calorimetry, Thermally Stimulated Depolarization Currents (TSDCs), and Broadband Dielectric Spectroscopy (BDS) and how they are affected by physical aging. Three dipolar relaxation modes can be observed: from slowest to fastest: the primary α relaxation, which vitrifies at the glass transition temperature, Tgα, and two secondary relaxations, named β* and β. Modulated differential scanning calorimetry results show how the secondary β* relaxation also vitrifies, giving rise to an additional glass transition at Tgβ* < Tgα.

The prevalence of sedentary behavior among university students in Saudi Arabia.

Background: A considerable body of research has demonstrated that reducing sitting time benefits health. Therefore, the current study aimed to explore the prevalence of sedentary behavior (SB) and its patterns.

Methods: A total of 6975 university students (49.

Insights into the Structural and Dielectric Behavior of Composites Produced from EPDM Waste Processed through a Devulcanization Method and SBR.

Ethylene propylene diene monomer (EPDM) is one of the most used polymers in the world. It is an elastomer, which means that the existing cross-linking between the main chains of the polymer created during the vulcanization process makes its recycling difficult. In this paper, a possible solution to this issue is studied.

Comparative dielectric and thermally stimulated-depolarization-current studies of the liquid crystal dimers 1″,9″-bis(4-cyanobiphenyl-4'-yl) nonane and heptane and a binary mixture between them, close to the glass transition.

We have performed dielectric spectroscopy and thermally stimulated-depolarization-current experiments to study the molecular dynamics of the twist-bend nematic phase close to the glass transition of two members of the 1″,7'-bis(4-cyanobiphenyl-4'-yl)alkane homologous series (CBnCB): the liquid crystal (LC) dimers CB9CB and CB7CB, as well as a binary mixture of both. By doping CB9CB with a small quantity of CB7CB, the crystallization is inhibited when cooling the sample down, while the bulk properties of CB9CB are retained and we can investigate the supercooled behavior close to the glass transition. The study reveals that the inter- and intramolecular interactions of the mixture are similar to those of pure CB9CB and confirms that there is a single glass transition in symmetric LC dimers.

Multi-Informant Assessment of Adolescents' Social-Emotional Skills: Patterns of Agreement and Discrepancy among Teachers, Parents, and Students.

Objectives: This study explores the patterns of agreement and discrepancy among informants (teachers, parents, and students) in the domains of the Social Emotional Skills Scale Assessment System-Social Skills Scales (SESAS-SS), which is a translation of the Social Skills Improvement System-Rating Scales (SSIS-RS) for use in Spain.

Methods: The sample is composed of students, 88 teachers, and 98 parents from Spanish secondary schools. Inter-rater agreements have been assessed, calculating the Pearson correlation coefficients among pairs of raters, effect size indices, and intraclass correlation coefficients at the subscale and total scale level.