Search results

The purpose of this paper is to enhance the water resistance and the heat resistance of poly(vinyl acetate) (PVAc) emulsion adhesive, by providing the emulsion with controllable thermosetting capability.

Emulsion polymerisation was used to synthesise PVAc/VeoVa 10 copolymers with varying proportions of acetoacetoxyethyl methacrylate (AAEM) incorporated in the copolymer chains. The AAEM component provided sites for crosslinking the chains via reaction of diamines with AAEM. The emulsion copolymers formed crosslinked films on addition of a range of diamines, during drying at ambient temperature. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterise the copolymerisation and crosslinking reaction. Glass transition temperatures of the polymer films were measured using dynamic mechanical thermal analysis to quantify the effects of copolymer composition variation and crosslinker. The performance of the crosslinked emulsions as wood adhesives was evaluated in accordance with the ISO 6238 standard by measuring the maximum shear stress of wood joints.

The crosslinking reaction between acetoacetoxy groups in the copolymer chains and the added diamines gives enamine structures, and occurs rapidly at ambient temperature. Major changes in the ¹³C NMR spectrum include the appearance of an enamine signal at 82 ppm, and disappearance of the acetoacetoxy carbonyl signal at 202 ppm. The new vibrational band at 1,597‐1,606 cm⁻¹ in the FTIR spectrum is assigned to the vibrations of the enamine double bond. The experimental results showed substantial increases in T_g and viscosity as the AAEM proportion in the copolymer emulsion increased. The crosslinked adhesives showed superior wood adhesive performance to unmodified PVAc emulsion.

It was necessary to adjust the pH of the emulsion for extended shelf life.

The method developed provides a simple and practical route to emulsions with improved water and heat resistance and bonding strength.

The method for enhanced water and heat resistance of PVAc wood adhesive was novel, straightforward and environmental friendly.

Both the criteria which can be used to assess the effectiveness of schools and the means by which effectiveness can be increased have received considerable attention during the last two decades. These criteria have usually been shown to revolve around school climate, leadership, shared decision making, effective teaching, and parental and community involvement. However, identification of universal criteria has been criticised on grounds such as poor methodology, differences in context and culture, assumptions of causality, and neglect of the influence of the external environment. Primary schools have goals and styles of operation which contrast markedly with those of secondary schools. Using approaches which differed from those commonly used in effectiveness studies, two Alberta studies asked principals (headteachers) to identify items which were (a) critical for planning and (b) important for judging the overall effectiveness of primary schools. Emphasis was placed on climate, high expectations for students, leadership, the morale and satisfaction of staff and students, effective teaching and student attitudes.

The job satisfaction and effectiveness of principals, the effectiveness of their schools, and relationships among those three variables were investigated by questionnaires and interviews involving elementary school teachers, principals, and area superintendents in Alberta. Job satisfaction of principals was closely associated with the effect of the job on their personal lives, and it was highest in respect of working relationships with teachers and students. An appropriate school climate emerged as the most important and most effective individual aspect of the performance of schools, but a multidimensional perspective was supported. Effective principalship was seen to encompass many high priority areas, and principals′ overall effectiveness related most strongly to their decision‐making effectiveness. Principals′ job satisfaction was only weakly associated with the effectiveness of schools and principals, but the two effectiveness variables were significantly related. Teachers and area superintendents tended to rate the effectiveness of schools less positively than did principals.

Drawing on the results of the previous chapters, this chapter looks at current progress in terms of climate disaster risk incorporation into development planning and practice at three levels (national government, municipalities, and communities) and analyzes gaps, challenges, and opportunities. The chapter also discusses potential factors for enhancing local disaster risk management (DRM) capacity by collaborating with three levels of stakeholders.

Mindfulness-based interventions are on the rise in workplace settings to enhance Well-Being and address work stress. Their popularity is in part due to the fact that they are often assumed to have a net positive impact on both workers’ Well-Being and organizational functioning. However, the majority of workplace mindfulness practice and research focuses on individual-level mindfulness interventions and their associated outcomes, like reduced stress. However, the modern workplace is highly dependent on positive team functioning, and the impact of mindfulness in teams is lesser known. This review differentiates individual mindfulness from team mindfulness and explores how both individual and team mindfulness impact team functioning. The authors review mindfulness and teams’ literature to understand antecedents, correlated mediators, and consequences of mindfulness in team contexts, team processes, and the boundary conditions related to mindfulness outcomes. This review adds to the budding theoretical conversation regarding mindfulness at work and contributes valuable insight into the practical applications of mindfulness in teams.

It's not enough to simply acquire alternative and small‐press materials. They must also be made easily accessible to library users by means of accurate, intelligible, and thorough cataloging.

Leaders have a profound impact on the work lives of the employees they supervise. This chapter explores the experiences of employees whose leaders exhibit toxic behaviors and the impact of this toxicity on employee engagement. The authors report the findings of a qualitative study involving in-depth interviews with 13 participants. First, the authors describe the participants’ experiences before and after experiencing toxicity. Next, the authors outline three critical toxic leadership styles: the nightmare (leaders who have unbalanced emotional control and who are overly fond of power), the pretender (leaders whose authenticity and integrity seem low, who play different characters depending on the circumstances), and the runaround (leaders who change directions too often or give unclear instructions). Finally, the authors address organizational, leadership, and individual strategies to identify and remove toxic leaders from the workplace.