نتایج جستجو برای: polyurethane foams
تعداد نتایج: 10571 فیلتر نتایج به سال:
Introduction The presence of certain heterocyclic rings with nitrogen atoms in an organic polymer may significantly improve its thermal stability. For typical polyurethane foams, the upper temperature range of save usage is usually considered to be 90-110°C [1, 2]. This limit can be improved by applying an oligoetherol component containing a thermostable heterocyclic ring with nitrogen atoms, s...
One of the most important challenges in polyurethane (PU) science is characterization of foam morphologies, which provides information to help understand material properties and improve synthesis conditions. Atomic force microscopy (AFM) is a very useful technique to obtain such information. A key challenge is to apply this technique to PU foams without destroying their cell structure. In this ...
The utilization of post-consumer car tires is an essential issue from ecological and economic point view. One the simplest least harmful methods their material recycling resulting in ground tire rubber (GTR), which can be further applied as fillers for polymer-based composites. Nevertheless, insufficient interfacial interactions implicate necessity GTR modification before introduction into poly...
in this research the composition of polyurethane closed cell (pucc) with two different concentrations of sio2 nanoparticles (1.0 and 2.0 wt%) have been prepared. optical microscopy and sem imaging, watering uptake, ftir and raman spectroscopy of the synthesized samples were carried out. the optical microscopy imaging of samples showed differences in the appearance of matrix produced by applying...
This paper investigates the impact of the irregular microgeometry of polyurethane acoustic foam on the macroscopic acoustic behavior predicted by a unit-cell model. Two semi-empirical unit-cell models coupled to a rigorous sensitivity analysis technique are used for this purpose. In these models, the porous material is idealized as a packing of a periodic unit-cell (PUC) representative of the d...
A variety of materials require functionally graded cellular microstructures whose porosity is engineered to meet specific applications (e.g. mimic bone structure for orthopaedic applications; fulfil mechanical, thermal or acoustic constraints in structural foamed components, etc.). Although a huge variety of foams can be manufactured with homogenous porosity, there are no generic processes for ...
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