Search results for " Plastic"
showing 10 items of 3463 documents
Molekulare Deutung der Umwandlungswärmen bei den Modifikationsübergängen des n-Tritriacontans
1978
Ausgehend von dem durch die Experimente nahegelegten Bild wurden Modellrechnungen angestellt, um die fur die drei Modifikationsumwandlungen desn-Tritriacontans gemessenen Umwandlungsenthalpien und -entropien molekular zu deuten.
Kommentar zu der Arbeit von Hans Craubner: „Lösefraktionierapparatur für makromolekulare Stoffe”
1976
Cyclopolymerisation bei zweifach-ungesättigten Monomeren
1967
Das Prinzip der Cyclopolymerisation wird erlautert; an Beispielen wird gezeigt, welche Verbindungen zu intra-intermolekularen Wachstumsschritten befahigt sind. Der Gehalt an cyclischen Grundbausteinen in den gebildeten Polymerisaten hangt auser von der Struktur der Monomeren auch von den Polymerisationsbedingungen ab. Es werden stereochemische Fragen behandelt, die im Zusammenhang mit Ringschlusreaktionen an 6- und hohergliedrigen Ringen auftreten. Chemische Umsetzungen an Cyclopolymeren konnen zu Copolymeren mit bestimmter Zusammensetzung und regelmasigem Aufbau fuhren.
Chemical Routes Toward Multicompartment Colloids
2012
The search for mimicking natural living and non-living systems with synthetic products leads to the fabrication of advanced colloidal morphologies with hierarchical micro- and nanostructures. Different chemical routes toward the synthesis of colloids with complex morphologies are presented and a tentative analogy between these routes and the four basic arithmetic operations is proposed.
Comparison of Different Processing Methods to Prepare Poly(lactid acid)–Hydrotalcite Composites
2013
The effect of the compounding method on the morphology and on the properties of poly(lactic acid) (PLA)-hydrotalcite (HT) composites was studied. Moreover, the influence of two different kinds of HT - organically modified (OM-HT) and unmodified (U-HT) - and their concentration was evaluated. The composites were prepared using either a single screw extruder (SSE), a counter rotating twin-screw compounder (TSC) or a corotating twin-screw extruder (TSE). The prepared materials were characterized by scanning electron microscopy, gel permeation chromatography (GPC) analysis, mechanical and rheological measurements. The results indicated that the best morphology, i.e., particles dimension and dis…
Distinct Patterns of Functional Connectivity During the Comprehension of Natural, Narrative Speech.
2020
Recent continuous task studies, such as narrative speech comprehension, show that fluctuations in brain functional connectivity (FC) are altered and enhanced compared to the resting state. Here, we characterized the fluctuations in FC during comprehension of speech and time-reversed speech conditions. The correlations of Hilbert envelope of source-level EEG data were used to quantify FC between spatially separate brain regions. A symmetric multivariate leakage correction was applied to address the signal leakage issue before calculating FC. The dynamic FC was estimated based on a sliding time window. Then, principal component analysis (PCA) was performed on individually concatenated and te…
Seismic evaluation of ordinary RC buildings retrofitted with externally bonded FRPs using a reliability-based approach
2020
International audience; Despite the extensive literature on reinforced concrete (RC) members retrofitted with fiberreinforced polymer (FRP) composites, few studies have employed a reliability-based approach to evaluate the seismic performance of RC buildings in terms of their collapse capacity and ductility. In this study, the performance of a poorly-confined RC building structure is investigated for different FRP retrofitting schemes using different configurations and combinations of wrapping and flange-bonded FRPs, as two well-established techniques. A nonlinear pushover analysis is then implemented with a computational reliability analysis based on Latin Hypercube Sampling (LHS) to deter…
Structural performances of pultruded GFRP emergency structures – Part 2: Full-scale experimental testing
2019
Abstract This paper presents an experimental testing of a pultruded glass fiber reinforced polymer (FRP) structure used for emergency applications continuing the discussion presented in a previous paper (part 1) where the study of the characteristics of material and elements are presented. First, the design of the composite structure and components and the evaluation of the structural behavior by means of numerical and analytical approach according to current regulatory codes are described. In this frame, the global and local response was observed according to load paths deriving from the design loads at limit states. Then, the experimental test on a full-scale 2D model is presented at diff…
Strategies for waste recycling : the mechanical performance of concrete based on limestone and plastic waste
2022
Recycling is among the best management strategies to avoid dispersion of several types of wastes in the environment. Research in recycling strategies is gaining increased importance in view of Circular Economy principles. The exploitation of waste, or byproducts, as alternative aggregate in concrete, results in a reduction in the exploitation of scarce natural resources. On the other hand, a productive use of waste leads to a reduction in the landfilling of waste material through the transformation of waste into a resource. In this frame of reference, the paper discusses how to use concrete as a container of waste focusing on the waste produced in limestone quarries and taking the challenge…
Torque rheometry investigation of model transreactions involving condensation polymers: I. Polyesters
2005
The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque-rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water-releasing substance …