Search results for " Plastic"
showing 10 items of 3463 documents
Reactive Compatibilization of PBT/EVA Blends with an Ethylene-Acrylic Acid Copolymer and a Low Molar Mass Bis-Oxazoline
2004
Polyesters and polyolefins form highly incompatible blends with poor properties and gross morphology that hinder any practical applications. In this work, the possibility to compatibilize an incompatible blend of poly(butylene terephthalate) (PBT) with ethylene vinyl acetate (EVA) by adding a bis-oxazoline compound, 2,2'-(1,3-phenylene)-bis(2-oxazoline) (PBO), and an ethylene acrylic acid copolymer (EAA) as compatibilizer precursors has been studied. The results indicate that the binary uncompatibilized blends show poor mechanical properties and a bad morphology with scarce adhesion between the phases. The situation is only slightly improved when the EAA is added while the best performance …
On the modification of the nitrile groups of acrylonitrile/butadiene/styrene into oxazoline in the melt
2000
Oxazoline functionality is well known to be highly reactive toward a lot of other functional groups like carboxyls, hydroxyls, mercaptans, and amines. In this work we report the possibility to modify the nitrile groups of an acrylonitrile/butadiene/styrene (ABS) copolymer into oxazoline in the molten state in the presence of aminoethanol as modifier agent and zinc acetate as a catalyst. The reaction has been carried out in a batch mixer and in a corotating twin screw extruder. The conversion of the nitrile groups into oxazoline has been verified by infrared spectroscopy, NMR analysis microanalysis and confirmed by thermomechanical characterization. The results indicate that the kinetic of g…
FRP reinforcement for concrete structures: state-of-the-art review of application and design
2014
Fiber reinforced polymers (FRPs) are considered to be a promising alternative to steel reinforcement, especially in concrete structures subjected to an aggressive environment or to the effects of electromagnetic fields. Although attempts to develop effective reinforcement have been followed, the application of FRPs remains limited by the solution to simple structural problems that mainly appear due to the absence of design codes, significant variation in the material properties of FRP composites and limited knowledge gained by engineers as regards the application aspects of FRP composites and structural mechanics of concrete elements reinforced with FRPs. To fill the latter gap, the current…
Measuring phenotypes in fluctuating environments
2020
Despite considerable theoretical interest in how the evolution of phenotypic plasticity should be shaped by environmental variability and stochasticity, how individuals actually respond to these aspects of the environment within their own lifetimes remains unclear. We propose that this understanding has been hampered by experimental approaches that expose organisms to fluctuating environments (typically treatments where fluctuations in the environment are cyclical vs. erratic) for a pre‐determined duration, while ensuring that the mean environment over that the entire exposure period is invariable. This approach implicitly assumes that responses to the mean and variance/predictability in th…
Acclimation capacity and rate change through life in the zooplankton Daphnia
2020
When a change in the environment occurs, organisms can maintain an optimal phenotypic state via plastic, reversible changes to their phenotypes. These adjustments, when occurring within a generation, are described as the process of acclimation. While acclimation has been studied for more than half a century, global environmental change has stimulated renewed interest in quantifying variation in the rate and capacity with which this process occurs, particularly among ectothermic organisms. Yet, despite the likely ecological importance of acclimation capacity and rate, how these traits change throughout life among members of the same species is largely unstudied. Here we investigate these rel…
Functional outcomes of peripheral nerve repair and regeneration: clinical and experimental study
This study investigated pre- and post-operative evaluation of peripheral nerve injuries and functional outcomes of peripheral nerve regeneration after different type of injuries and different type of treatments. Neuromas/scar neuritis and brachial plexus injuries are specifically addressed; literature and experimental evidence on the outcomes of vascularized nerve grafts are presented.
The face-lift smas plication (FLISP) flap for reconstruction of large temporal defect. Reconstructive surgery meets cosmetic surgery
2012
Effect of different processing techniques and presence of antioxidant on the chitosan film performance
2022
In the last two decades, the naturally occurring polysaccharides have gained great attention because of their potential applications in different sectors, for example, from food to biomedical sectors. Chitosan is a cationic polysaccharide with good transparency, and currently, it has been considered also as suitable material for the formulation film and coating in cultural heritage protection. In this work, the chitosan films (Ch), with and without natural antioxidant such as citric acid (CA), are formulated considering two different processing techniques: (i) conventional solvent casting and (ii) compression molding, that is an unconventional method for this polysaccharide, giving the poss…
Tadpole Responses to Environments With Limited Visibility: What We (Don’t) Know and Perspectives for a Sharper Future
2022
Amphibian larvae typically inhabit relatively shallow freshwater environments, and within these boundaries there is considerable diversity in the structure of the habitats exploited by different species. This diversity in habitat structure is usually taken into account in relation to aspects such as locomotion and feeding, and plays a fundamental role in the classification of tadpoles into ecomorphological guilds. However, its impact in shaping the sensory worlds of different species is rarely addressed, including the optical qualities of each of these types of water bodies and the challenges and limitations that they impose on the repertoire of visual abilities available for a typical vert…
Intergenerational fitness effects of the early life environment in a wild rodent
2019
The early life environment can have profound, long‐lasting effects on an individual's fitness. For example, early life quality might (a) positively associate with fitness (a silver spoon effect), (b) stimulate a predictive adaptive response (by adjusting the phenotype to the quality of the environment to maximize fitness) or (c) be obscured by subsequent plasticity. Potentially, the effects of the early life environment can persist beyond one generation, though the intergenerational plasticity on fitness traits of a subsequent generation is unclear. To study both intra‐ and intergenerational effects of the early life environment, we exposed a first generation of bank voles to two early life…