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.
Poly(lactic acid) (PLA) is used in packaging applications, but its moisture barrier properties are inferior to poly(ethylene terephthalate) and polystyrene. One objective of the study was to improve these by dispersing nanoclay in PLA. It was found that Cloisite 30B nanoclay showed the best dispersion based on both permeability and transmission electron microscopy results. Compression molded nanocomposite films were amorphous, and moisture permeability measurements revealed that, at the highest loading level of 5.3 vol % organoclay, permeability was reduced by 69% compared to neat PLA. Additionally, independent experiments demonstrated that moisture solubility in the polymer remains unchanged even as solubility in the nanocomposite increases with increasing clay content. A second objective was to explain the measured permeability reduction. A new model is proposed where both the mass flux and area for mass transfer are reduced due to a tortuous path around the impermeable barriers. It is shown that the permeability decreases by a factor of true(1+h2tφtrue)2 where h/t is the aspect ratio of the nanoplatelets, and ϕ is their volume fraction. Model predictions agree quantitatively with the measured permeability values when data are obtained as a function of filler volume fraction, temperature of measurement, and the concentration driving force. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46506.
The stability of bleeder entries is essential for both mine ventilation and personnel travelling through the entries. Therefore, it is imperative that bleeder pillars remain stable and bleeder entries safe during their service life. Surprisingly, there are few published investigations on ground control issues in the bleeder entries. This thesis is an attempt to analyze the ground control problems in bleeder entries especially, the structural integrity of the bleeder entry. Two numerical programs (a) displacement discontinuity program-LaModel and (b) the finite difference program-FLAC were used to investigate these problems. Modeling results from the LaModel program indicated that the vertical stresses in bleeder pillars would first increase and then remain unchanged during retreat mining. The active longwall did not influence the stress concentrations and safety factors in the bleeder pillars of the adjacent mined-out panel in multiple longwall panels. The vertical stress concentration on bleeder pillars increased with depth. For detailed analysis of roof, pillar and floor of the mine entry simulation was performed in the finite difference program-FLAC. For realistic analysis, coal was assigned as strain-softening material and the gob was simulated with double yielding material. Results showed that the roof displacement in bleeder entries increased during second mining. The stability of the bleeder entry was affected by the behavior of the gob and active mining zone. This is where my journey begins in West Virginia. After two years study in Morgantown, lots of memories were, are and will always be preserved here: the WVU Stadium, PRT (Personal Rapid Transit), Creative Art Center, Recreation Center, WVU library, Mineral Resource Building, Pineview, WVUCSSA, Christian & Missionary Alliance (CMA) Church, Cheat Lake, Metropolitan Theater, and so on. These are the places where I have experienced American culture, where I have shared my joys and sorrows with my friends, where I have learned how to live my life, and where I have found my true passion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.