Effect of ZnO on the Thermal Degradation Behavior of Poly(Methyl Methacrylate) Nanocomposites

Abstract

In the memory of Janez (Janko) Jamnik our dear friend and co-worker. AbstractThe influence of ZnO nanoparticles on the thermal degradation behavior of poly(methyl methacrylate) (PMMA) was tested using thermoanalytical techniques. The studied materials were investigated using TG, DTA, EGA, XRD, SEM and TEM. The ZnO nanoparticles were synthesized via precipitation by adding LiOH into Zn 2+ water/ethylene glycol solutions. The ZnO-PMMA nanocomposites were prepared by adding the appropriate amount of ZnO into MMA and subsequent MMA radical polymerization. According to the experimental results and model-free isoconversional activation energy calculations, the addition of ZnO into PMMA played a double role. The ZnO concentrations up to 0.15% stabilized the composite by shifting the degradation interval toward higher temperatures and increasing the apparent activation energy relative to pure PMMA. At higher concentrations, the catalytic effect of ZnO started to prevail and was reflected in the lower temperature intervals of intense PMMA degradation and lower apparent activation energy. The addition of ZnO generally did not change the nature of the PMMA decomposition process.

Evolution of ZnO microstructures from hexagonal disk to prismoid, prism and pyramid and their crystal facet-dependent gas sensing properties

“…† 73 It is widely known that the (0001) polar plane of ZnO contains more oxygen vacancies than other facets and it is also proved by the PL characterization in this study. 64,65 These oxygen vacancies can significantly enhance the oxygen molecular adsorption and promote the dissociative adsorption, in which one of the oxygen atoms fills the original oxygen vacancy, while the other forms a bridging oxygen adatom between two Zn atoms, 71,74 as expressed by eqn (7) or (8) shown in the ESI. † 75 Moreover, for hexagonal ZnO, Zn atoms on the surface are usually coordinatively unsaturated, while the Zn and O atoms in the bulk are 4-fold coordinated.…”

“…As one of the important metal oxide semiconductor materials, zinc oxide (ZnO), with a wide bandgap of 3.37 eV and large exciton binding or Rydberg energy of ~60 meV, has been actively studied due to its excellent chemical/electrical/ optical properties and easy growth of desired nanostructures for functional devices, such as sensors, solar cells, light emitting diodes, and ultraviolet lasers. [1][2][3][4][5] To date, ZnO micro/ nanostructures such as zero-dimensional (0D) quantum dots; [6][7][8] one-dimensional (1D) nanorods, [9][10][11] nanowires [12][13][14] and nanotubes; 15 two-dimensional (2D) nanosheets 16 and nanobelts; 17 even three-dimensional (3D) nanoflowers 18 and hollow structures, 19 etc., have all been prepared successfully by using either physical deposition or chemical methods.…”

Microwave-assisted synthesis of ZnGa2−x−yEuxTbyO4 luminescent nanoparticles showing balanced white-light emission

“…The band at 425 cm À1 corresponds to Ga-O vibrations, 33,34 whereas the band at 597 cm À1 corresponds to the characteristic Zn-O vibrations. 35,36 This band at 597 cm À1 implies that the Zn-O bond is formed during synthesis and becomes prominent with annealing. The sharp band at 1384 cm À1 can be attributed to the nitrate ions; 37 this band vanishes when the sample was annealed at 700 1C and above, indicating that a minimum of 700 1C annealing is required to get good quality (Eu, Tb)-doped ZnGa 2 O 4 nanoparticles.…”

Thermal Degradation of Polystyrene (PS) Nanocomposites Loaded with Sol Gel-Synthesized ZnO Nanorods

“…The delay in the thermal degradation of such investigated nanocomposites was attributed to fine dispersions of used nanofillers. In addition, the high heat capacity and good thermal conductivity of ZnO nanoparticles made them act as good heat sinkers that overcame the amount of heat that the PS polymer backbone could gain and hence enhancement in thermal stability of the composites is attained [25]. Figure 5b shows the obtained DTG curves of all PS/ZnO nanocomposites.…”

“…N,Ndimethylformamide (DMF, (Alfa Aesar, Haverhill, MA, USA)) was used for the preparation of PS/ZnO nanocomposites. ZnO nanocrystals in rod-like shapes that were synthesized using sol-gel route as reported elsewhere [ 24 , 25 ] were used as nanofillers. In such a typical route, zinc acetate dehydrate (Zn(CH 3 COO) 2 .H2O), isopropanol and diethanolamine (HN(CH 2 CH 2 OH) 2 , DEA) (Sigma-Aldrich, St. Louis, MO, USA) were used as salt precursor, solvent and chelating agent, respectively.…”