Abstract:Nanocomposites were prepared with segmented polyurethanes and Cloisite 30B by either solution mixing or in situ polymerization and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. Cytotoxicity and genotoxicity were assessed with lymphocytes while cell viability was measured by the methyl tetrazolium assay using fibroblasts. It was found that in situ polymerization rendered exfoliated nanocomposites with higher glass t… Show more
“…Our analysis showed that in the 2θ range of 5–80°, both PLA and PLACC displayed broad peaks around 15.4 and 18.1°, respectively (Fig. 2a ), which are characteristic of neat PLA 90 thus confirming the amorphous structure and low crystallinity of the samples 79 , 91 likely induced by the high cooling rates used during the molding process of the polymer 92 . Figure 2 Physical characteristics analysis.…”
Section: Resultsmentioning
confidence: 56%
“…Similar results were obtained by Moo-Espinosa et al ., when CC was exfoliated into segmented polyurethanes at concentrations of 2, 6, or 10 wt. %, respectively 79 .…”
Addition of nanoclays into a polymer matrix leads to nanocomposites with enhanced properties to be used in plastics for food packaging applications. Because of the plastics’ high stored energy value, such nanocomposites make good candidates for disposal via municipal solid waste plants. However, upon disposal, increased concerns related to nanocomposites’ byproducts potential toxicity arise, especially considering that such byproducts could escape disposal filters to cause inhalation hazards. Herein, we investigated the effects that byproducts of a polymer polylactic acid-based nanocomposite containing a functionalized montmorillonite nanoclay (Cloisite 30B) could pose to human lung epithelial cells, used as a model for inhalation exposure. Analysis showed that the byproducts induced toxic responses, including reductions in cellular viability, changes in cellular morphology, and cytoskeletal alterations, however only at high doses of exposure. The degree of dispersion of nanoclays in the polymer matrix appeared to influence the material characteristics, degradation, and ultimately toxicity. With toxicity of the byproduct occurring at high doses, safety protocols should be considered, along with deleterious effects investigations to thus help aid in safer, yet still effective products and disposal strategies.
“…Our analysis showed that in the 2θ range of 5–80°, both PLA and PLACC displayed broad peaks around 15.4 and 18.1°, respectively (Fig. 2a ), which are characteristic of neat PLA 90 thus confirming the amorphous structure and low crystallinity of the samples 79 , 91 likely induced by the high cooling rates used during the molding process of the polymer 92 . Figure 2 Physical characteristics analysis.…”
Section: Resultsmentioning
confidence: 56%
“…Similar results were obtained by Moo-Espinosa et al ., when CC was exfoliated into segmented polyurethanes at concentrations of 2, 6, or 10 wt. %, respectively 79 .…”
Addition of nanoclays into a polymer matrix leads to nanocomposites with enhanced properties to be used in plastics for food packaging applications. Because of the plastics’ high stored energy value, such nanocomposites make good candidates for disposal via municipal solid waste plants. However, upon disposal, increased concerns related to nanocomposites’ byproducts potential toxicity arise, especially considering that such byproducts could escape disposal filters to cause inhalation hazards. Herein, we investigated the effects that byproducts of a polymer polylactic acid-based nanocomposite containing a functionalized montmorillonite nanoclay (Cloisite 30B) could pose to human lung epithelial cells, used as a model for inhalation exposure. Analysis showed that the byproducts induced toxic responses, including reductions in cellular viability, changes in cellular morphology, and cytoskeletal alterations, however only at high doses of exposure. The degree of dispersion of nanoclays in the polymer matrix appeared to influence the material characteristics, degradation, and ultimately toxicity. With toxicity of the byproduct occurring at high doses, safety protocols should be considered, along with deleterious effects investigations to thus help aid in safer, yet still effective products and disposal strategies.
“…SPU was synthesized according to Ref. 21 using a molar ratio of 2.05:1:1 of 4,4 0 -methylene bis (cyclohexyl isocyanate):1,4 butanediol:poly (tethramethylene glycol ether). The first two were purchased from Simga-Aldrich (Sigma-Aldrich, Milwaukee; www.sigmaaldrich.com) while the last one was acquired from Lyondell (Lyondell Chemical Company, Barcelona, Spain; www.lyondellbasell.com), with an approximate M n of $2000 g/mol.…”
Section: Materials Used For Composite Preparationmentioning
Multiwall carbon nanotube (MWCNT)/elastomeric composite films were fabricated using two segmented polyurethanes: an in-house synthesized one (SPU) and a commercial medical grade one (Tecoflex V R , TF). Electrical, mechanical, and electromechanical (piezoresistive) properties of both composites were evaluated as a function of the MWCNT weight concentration (1-10 wt %). An increase in electrical conductivity for both types of polymers was observed for MWCNT concentrations as low as 1 wt %. The electrical conductivity of MWCNT/TF composites was higher than that achieved for MWCNT/SPU composites. Mechanical properties of 8 wt % MWCNT/SPU composites showed a threefold increase in stiffness compared to neat SPU. The changes in electrical resistance of the composites showed higher sensitivity to strain for lower MWCNT concentrations. The piezoresistive signal of the composites allows to measure strains up to $400% before electrical depercolation occurs. The strain at which electrical depercolation occurs depends on the conductivity of the composite in its unloaded state. This kind of composites may find sensing applications in prosthetics, biomedical devices, and smart textiles.
“…Two-step decomposition usually occurs with segmented polyurethane materials and confirms good phase separation [ 49 ]. The first peak with a maximum degradation rate of ~330 °C may be due to the degradation of hard segments of PU, leading to the formation of amines, low-molecular-weight components, and carbon dioxide [ 50 ]. The shift of T max2 to lower temperatures may be caused by the higher degree of interfacial separation between soft and hard segments, which may be caused by interactions of both phases with montmorillonite plates [ 51 ].…”
Section: Resultsmentioning
confidence: 99%
“…Examples of deconvolution results are shown in Figure 4 , and results of calculations are presented in Table 4 . The area under the curves was calculated, and the percentage content of rigid segments was estimated similarly to the results obtained by Moo-Espinosa [ 50 ]. In the case of DTG curves of nanocomposite samples presented in Figure 4 a, the Gaussian calculation method was used.…”
In recent years, polyurethane nanocomposites have attracted more attention due to the massive demand for materials with increasingly exceptional mechanical, optical, electrical, and thermal properties. As nanofillers have a high surface area, the interaction between the nanofiller and the polymer matrix is an essential issue for these materials. The main aim of this study is to validate the impact of the montmorillonite nanofiller (MMT) surface structure on the properties of polyurethane thin-film nanocomposites. Despite the interest in polyurethane–montmorillonite clay nanocomposites, only a few studies have explored the impact of montmorillonite surface modification on polyurethane’s material properties. For this reason, four types of polyurethane nanocomposites with up to 3% content of MMT were manufactured using the prepolymer method. The impact of montmorillonites on nanocomposites properties was tested by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurement, X-ray diffraction (XRD), and optical coherence tomography (OCT). The results showed that chemical and physical interactions between the polymer matrix and functional groups on the montmorillonite surface have a considerable impact on the final properties of the materials. It was noticed that the addition of MMT changed the thermal decomposition process, increased T2% by at least 14 °C, changed the hydrophilicity of the materials, and increased the glass transition temperature. These findings have underlined the importance of montmorillonite surface structure and interactions between nanocomposite phases for the final properties of nanocomposites.
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