Search results for "blend"

Polymer Incompatibility Caused by Different Molecular Architectures: Modeling via Chain Connectivity and Conformational Relaxation

2009

The calculation of phase diagrams for blends of linear and branched polymers made up of identical monomeric units is modeled using an approach that subdivides the mixing process into two steps: i) contact formation between the different components, keeping their chain conformations and the volume of the system constant; and, ii) relaxation of the macromolecules into their equilibrium state by molecular rearrangements. It is assumed that step (ii) causes shape-induced polymer incompatibility and that the degree of branching can be quantified in terms of the volumes the isolated coils of the branched polymer occupy in relation to the volume the linear product with the same molecular weight oc…

Novel antimicrobial ultrathin structures of zein/chitosan blends obtained by electrospinning

2009

Abstract This paper describes the formulation, morphology and biocide properties of novel antimicrobial electrospun zein based ultrathin fiber structures. From the results, it was found that the electrospun fibers of zein can turn the material into a new strong antimicrobial ultrathin-structured system due to retention of remnant amounts of trifluoroacetic acid as determined by ATR–FTIR spectroscopy. Unfortunately, this system may be considered to yield very aggressive high acidic media due to release of the strong acid, which causes the antimicrobial behavior. Nevertheless, since biocide properties are more desirable at mild acidic conditions, blending zein with the natural antimicrobial c…

The Effects of Nanoclay on the Mechanical Properties, Carvacrol Release and Degradation of a PLA/PBAT Blend

2020

The formulation of polymeric films endowed with the abilities of controlled release of antimicrobials and biodegradability is the latest trend of food packaging. Biodegradable polymer (Bio-Flex&reg

Blending PLLA with PLA so as to tune the biodegradabilty of polymeric scaffolds for soft tissue engineering

2008

Teaching Competences Through ICTs in an English Degree Programme in a Spanish Setting

2012

In this chapter I shall describe the ways in which a group of lecturers in English language and linguistics have attempted to help students acquire competencies using ICTs in an English Studies degree programme in Spain. The introduction of competence-based learning constitutes a major paradigm shift brought about by the convergence of degree systems in the European Higher Education Area, and is part of a concerted effort to make our degrees less teacher-centred with a view to giving students greater opportunities to participate in their own learning process, both inside and outside the classroom. I will outline how general and discipline-specific competences are acquired through the use of…

The Role of Motivation, Cognition, and Conscientiousness for Academic Achievement

2013

Based on a cognitive motivational process model of learning, the impact of studying behavior on learning outcome is investigated. First-year students ( N = 488) participated in the study. Two research questions were addressed: (1) Can cognitive-motivational variables and objective study behavior predict individual learning? (2) Which factors drive studying behavior? Results show low to moderate correlations between cognitive-motivational variables and performance. A cluster analysis yielded three profiles: (1) interested learners with high academic self-concept and effort investment; (2) low interest learners with high academic self-concept and low effort investment; and (3) interested lear…

Teachers' instructional scaffolding in an innovative information and communication technology-based history learning environment

2002

Abstract The nature of the role assumed by the teacher is crucial in the promotion of successful learning and collaboration in Information and Communication Technologybased (ICT-based) environments. The aim of this study was to examine how teachers with different conceptions of their teacher roles use different types of instructional scaffolding while working in an innovative learning environment. Our further aim was finding out how instructional scaffolding is related to learning activities of different kinds. The study was carried out at two secondary schools with a shared network-based learning environment. The results showed that teachers with different conceptions of the teacher's role…

Perceived Support in E-Collaborative Learning: An Exploratory Study Which Make Use of Synchronous and Asynchronous Online-Teaching Approaches

2012

This study compares four different learning environments for e-collaborative learning in two European countries related to the dimension of student's mutual support. The theoretical baseline is Vygotsky's zone of proximal development (ZOPD) and the socio-genetic approach of Piaget. The analyzed data are based on questionnaires collected over the time period of an entire semester including four different courses at the master's level. These courses applied different e-collaborative approaches including a variety of tools for supporting communication. It is assumed that these courses including communication tools e.g. virtual face-to-face meetings enhance the chances for better communication,…

Internet-based learning environments for project-enhanced science learning

2002

From Online Role-Play to Written Argumentation

2010

This chapter reports on a teaching experiment conducted during a blended learning course in social work in a Finnish university of applied sciences (polytechnic). The aim was to investigate how students’ multidimensional understanding of social problems could be fostered. As argumentative methods, the study used writing tasks, online role-play, and drama work. The data consisted of essays written by 65 students (experimental group 29; controls 36) in each of three phases, plus online discussions. The essays were based on 1) the students’ personal experiences, 2) general facts, and 3) a fictional case taken from the online role-play. Varying the focus of the writing task affected students’ s…