Investigating the effects of chemical modification of clay nanoparticles on thermal degradation and mechanical properties of TPU/nanoclay composites

Thermoplastic polyurethane (TPU)/clay nanocomposites were prepared via a melt-compounding method using ester type TPU and two different modified organoclays (Cloisite 30B and Cloisite 15A) in different contents. The Effects of the chemical structure and content of the nanoclays on the thermal degradation and mechanical properties of TPU were also investigated. The effect of structural modification on dispersion during melt compounding has been studied by XRD and FTIR analysis. Barrier effect formation and thermal stability in both nanocomposites containing different nanoparticle content have been studied. The effect of chemical modification of the nanoparticles on mechanical properties in all contents has been investigated. The XRD results show that better dispersion near the exfoliated structure obtained for cloisite 30B is due to good interaction via hydrogen bonding between the TPU chains and layered silicate. A high content of the nanoparticles leads to disordering of soft and hard segments in the TPU chains, which is confirmed by FTIR. Mechanical properties analysis shows that the TPU/Cloisite 30B nanocomposites have higher modulus and tensile strength as well as elongation at break by the addition of 2% in both cloisite 30B (C30B) and cloisite 15A (C15A) than other contents of nanoclays

Synthesis of Shape Memory Polyurethane/Nanoclay Composites: Chemical Structure and Interactions between Polymer and Nanoclay Particles

Although  there  are many works  published  on  shape memory  polyurethanes, but  no  report  is  found  on  PCL-based  polyurethane  composite  using  PCL with  molecular  weight  of  2000  g/mol  and  nanoclay  particles  via  in-situ polymerization.  In  this  work,  we  try  to  approach  some  problems  concerning  the chemical structure, dispersion of a noparticles in the matrix and interaction between nanoparticles  and  polymer  in  shape  memory  of  PCL  (Mn=  2000  g/mol)-based  polyurethane/nanoclay  composites.  While  PCL  (Mn=  2000  g/mol)  polyurethane constituted the soft segments, MDI/BD formed the hard segments. The weight ratio of  soft  to  hard  segments was  found  to  be  65/35. Composites were  synthesized  in presence 1 and 3 wt% of nanoclay (Cloisite®30B) via in-situ polymerization by a two-step method. Effect of nano particles on their interactions with polyurethane chains, crystallinity, mechanical properties and shape memory have been investigated usin

Self Disinfecting Reversible Hydrocolloid Impression Gels: Effect of Composition and Nanosilver on Characteristic Properties and Gelation Temperature

We have developed a new hydrocolloid impression gel to eliminate disinfection process that caused to inaccuracy in dimensions of final mold. At first, the proper sample has been prepared based on recommended formulation in literature as well as trial and errors via experimental works. Formulations prepared by variation amounts of ingredients and also samples prepared by adding nanosilver as an antibacterial agent. Characteristic properties such as tear strength, gel temperature, compressive strength and elastic recovery of prepared hydrocolloid impression gels have been evaluated. The effect of agar, potassium sulfate and di-sodiumtetraborate (Borax) on characteristic properties has been investigated. In addition, role of nanosilver as an antibacterial which can be eliminate disinfecting process, on final properties of gels has been evaluated this work presents the role of ingredient on properties of self disinfecting agar impression gel

Intumescent flame retardant polyurethane/starch composites: thermal, mechanical, and rheological properties

Intumescent flame retardant polyurethane/starch (IFRPU/starch) composites were prepared by means of melt blending. Microencapsulated ammonium polyphosphate (MCAPP) was added to improve its compatibility with matrix, retardation of reaction between acid and carbon source, and its water resistancy. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of hydrogen bonding and entangled network between IFR system and PU matrix. Further, scanning electron microscopy (SEM) illustrated homogeneity of starch in matrix. By addition of 10 wt % of starch and 20 wt % of IFR, limiting oxygen index (LOI) increased from 22.0 to 40.0 and UL94 V0 rating was achieved. Differential scanning calorimetry (DSC) detected three endothermic transitions and one glass transition (T-g). The temperature of transition III and T-g increased with starch due to crosslinking between PU and starch. The improved thermal stability in the presence of starch was confirmed by thermogravimetric analysis (TGA). Beside the fact that starch was used as a carbonization agent to improve flame retardancy, it also effectively led to enhanced mechanical and viscoelastic properties. (C) 2014 Wiley Periodicals, Inc

Proliferation and osteogenic differentiation of mesenchymal stem cells on three-dimensional scaffolds made by thermal sintering method

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Hopes Beyond PET Recycling: Environmentally Clean and Engineeringly Applicable

International audienc