Synergistic Effects of Surface Chemistry and Topologic Structure from Modified Microarc Oxidation Coatings on Ti Implants for Improving Osseointegration

2015 ◽  
Vol 7 (16) ◽  
pp. 8932-8941 ◽  
Author(s):  
Rui Zhou ◽  
Daqing Wei ◽  
Jianyun Cao ◽  
Wei Feng ◽  
Su Cheng ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Synergistic Effects ◽  
Microarc Oxidation ◽  
Topologic Structure

scholarly journals Defluorination of Polytetrafluoroethylene Surface by Hydrogen Plasma

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2855
Author(s):  
Alenka Vesel ◽  
Dane Lojen ◽  
Rok Zaplotnik ◽  
Gregor Primc ◽  
Miran Mozetič ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Photoelectron Spectroscopy ◽  
Treatment Time ◽  
Synergistic Effects ◽  
Surface Film ◽  
Hydrogen Plasma ◽  
Contact Angles ◽  
Hydrogen Atoms ◽  
Tof Sims ◽  
Discharge Parameters

Defluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H2 plasma sustained in the E- and H-modes at various powers, pressures and treatment times. The surface finish was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The measurements of water contact angles (WCA) showed increased wettability of the pristine PTFE; however, they did not reveal remarkable modification in the surface chemistry of the samples treated at various discharge parameters. By contrast, the combination of XPS and ToF-SIMS, however, revealed important differences in the surface chemistry between the E- and H-modes. A well-expressed minimum in the fluorine to carbon ratio F/C as low as 0.2 was observed at the treatment time as short as 1 s when plasma was in the H-mode. More gradual surface chemistry was observed when plasma was in the E-mode, and the minimal achievable F/C ratio was about 0.6. The results were explained by the synergistic effects of hydrogen atoms and vacuum ultraviolet radiation.

Surface Chemistry of Nanocrystalline Cerium Oxide

1994 ◽  
Vol 351 ◽  
Author(s):  
Andreas Tschöpe ◽  
J.Y. Ying ◽  
K. Amonlirdviman ◽  
M. L. Trudeau
Keyword(s):  
Surface Chemistry ◽  
Cerium Oxide ◽  
Photoelectron Spectroscopy ◽  
Synergistic Effects ◽  
Oxygen Deficiency ◽  
High Surface ◽  
Reaction Chamber ◽  
Surface Reactivity ◽  
Promoting Effect ◽  
Reduction And Oxidation

ABSTRACTNanocrystalline cerium oxide was synthesized by magnetron sputtering of a metallic target, followed by controlled post-oxidation. The resulting cerium oxide clusters were <10 nm in size, and highly non-stoichiometric in nature. The oxygen deficiency of such materials was associated with the unusual catalytic activity in oxidation and redox reactions. This paper compares the surface chemistry of nanocrystalline CeO2−x with stoichiometric CeO2. It further explores the promoting effect of Cu-doping on surface reduction and oxidation.The oxidation states of metal cations were examined with X-ray photoelectron spectroscopy after various oxidizing and reducing heat treatments in a connected reaction chamber. Isothermal pulsed reduction and oxidation of the samples were investigated by thermogravimetric analysis. Reduction properties of the different materials are discussed in terms of their microstructure, oxygen deficiency and chemical composition. These studies will help to understand the importance of bulk defects and synergistic effects in multicomponent and multiphase materials for high surface reactivity.

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

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