scholarly journals The influence of shaped TiO2 nanofillers on thermal properties of polyvinyl alcohol

2012 ◽  
Vol 77 (5) ◽  
pp. 699-714 ◽  
Author(s):  
Marija Radoicic ◽  
Zoran Saponjic ◽  
Milena Marinovic-Cincovic ◽  
Scott Ahrenkiel ◽  
Natasa Bibic ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Tio2 Nanoparticles ◽  
Polymer Matrix ◽  
Oxidative Degradation ◽  
Inert Atmosphere ◽  
Titania Nanotubes ◽  
Crystallinity Degree ◽  
Degradation Temperature ◽  
Thermal Stability Of ◽  
Thermo Oxidative Degradation

PVA-based nanocomposites consisting of shaped TiO2 nanocrystals (nanoparticles, nanotubes or nanorods) were synthesized by direct blending of polymer and titania nanocrystals solution or powder. In order to elucidate the influence of shape of titania nanocrystals on thermal stability of polymer matrix and particles interaction with PVA chain, structural and thermal characterizations of PVA/TiO2 nanocomposites were performed. Faceted nanoparticles increased the thermal stability of PVA matrix. Titania nanotubes and nanorods did not show any stabilizing effect on polymer matrix in argon atmosphere. The thermo-oxidative degradation temperature of PVA increased with addition of faceted TiO2 nanoparticles. The thermo-oxidative stability of the PVA matrix was affected more by the presence of titania nanotubes and nanorods in comparison with its thermal stability in inert atmosphere. The crystallinity degree (Xc=32 %) of PVA matrix slightly decreased in the presence of faceted TiO2 nanoparticles in nanocomposite sample.

scholarly journals Characteristics of Biodegradable Polylactide/Thermoplastic Starch/Nanosilica Composites: Effects of Plasticizer and Nanosilica Functionality

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Regina Jeziorska ◽  
Agnieszka Szadkowska ◽  
Ewa Spasowka ◽  
Aneta Lukomska ◽  
Michal Chmielarek
Keyword(s):  
Thermal Stability ◽  
Oxidative Degradation ◽  
Thermoplastic Starch ◽  
Silica Content ◽  
Screw Extruder ◽  
Elongation At Break ◽  
Twin Screw ◽  
Thermal Stability Of ◽  
Better Than ◽  
Thermo Oxidative Degradation

The effect of plasticizer (polydimethylsiloxanol) and neat (SiO2) or modified (having amine functional groups) silica (A-SiO2) on morphology, thermal, mechanical, and rheological properties of PLA/TPS blends compatibilized by maleated PLA (MPLA) was investigated. Toughened PLA/MPLA/TPS (60/10/30) blend containing 3 wt.% of plasticizer and various contents (1, 3, or 5 wt.%) of silica were prepared in a corotating twin-screw extruder. From SEM, it is clear that plasticized PLA/MPLA/TPS blend continuous porous structure is highly related to the silica content and its functionality. The results indicate that polydimethylsiloxanol enhances ductility and the initial thermal stability of the plasticized blend. DSC and DMTA analyses show that nucleation ability and reinforcing effect of A-SiO2on plasticized blend crystallization are much better than those of SiO2. Silica practically had no effect on the thermo-oxidative degradation. However, the composites with A-SiO2had better thermal stability than those with SiO2. Moreover, silica significantly improved the elongation at break.

Effect of the hydrophilicity of the polymer matrix on immobilized α-chymotrypsin

1984 ◽  
Vol 49 (6) ◽  
pp. 1552-1556
Author(s):  
Minoru Kumakura ◽  
Isso Kaetsu
Keyword(s):  
Thermal Stability ◽  
Enzyme Activity ◽  
Pore Size ◽  
Polymer Matrix ◽  
Low Temperatures ◽  
Radiation Polymerization ◽  
Thermal Stability Of

α-Chymotrypsin was immobilized by radiation polymerization at low temperatures and the effect of the hydrophilicity of the polymer matrix on the enzyme activity and thermal stability was studied. The activity and thermal stability of immobilized chymotrypsin increased with the increasing hydrophilicity of the polymer matrix or monomer. The thermal stability was affected by the form and pore size of the polymer matrix; chymotrypsin immobilized on a soft-gel polymer matrix exhibited an enhanced thermal stability.

Thermal and Thermo-Oxidative Degradations of Deproteinized Natural Rubber and Natural Rubber

2011 ◽  
Vol 306-307 ◽  
pp. 50-57 ◽  
Author(s):  
Can Zhong He ◽  
Zheng Peng ◽  
Jie Ping Zhong ◽  
Shuang Quan Liao ◽  
Xiao Dong She ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Natural Rubber Latex ◽  
Oxidative Degradation ◽  
Decomposition Reaction ◽  
Nitrogen Atmosphere ◽  
Degradation Temperature ◽  
Air Atmosphere ◽  
Deproteinized Natural Rubber

Deproteinization of natural rubber was achieved in the latex stage. The structure of deproteinized natural rubber (DPNR) was characterized by fourier transform infrared spectroscopy (FTIR). The thermo degradation of DPNR was studied by thermogravimetry analysis (TG) under air atmosphere and nitrogen atmosphere. The kinetic parameters apparent activation energies (Ea) of the thermal decomposition reaction been calculated from the TG curves using the method described by Broido. And the results were compared with the thermo degradation of natural rubber (NR) under the same conditions. The effect of proteins in natural rubber latex on thermal/ thermo-oxidative stability of NR was discussed. The results show that: the absorptions of the proteins in DPNR at 1546 ㎝-1, compared to NR, become significantly weaker, nearly disappear, which indicates most of proteins has been removed from NR. The thermo degradation of DPNR in nitrogen atmosphere is a one-step reaction. The initial degradation temperature (T0) 、the maximum degradation temperature（Tp） and the final degradation temperature（Tf）as well as the Ea of DPNR are higher than those of NR, which indicates that DPNR represents a better thermal stability than NR under nitrogen atmosphere. Thermo-oxidative degradation of DPNR and NR are two-step reaction. The characteristic temperatures (T0, Tp and Tf) of DPNR are lower than those of NR. The Ea during the First Step of Thermooxidative Degradation of DPNR are also lower than those of NR. These results prove that the thermo-oxidative stability of DPNR is worse than that of NR. Protein is the key role to the thermal stability of natural rubber.

Thermal and viscoelastic behaviors of nanotube-reinforced polyethylene composite

2011 ◽  
Vol 1312 ◽  
Author(s):  
Ananta Raj Adhikari ◽  
Mircea Chipara ◽  
Karen Lozano
Keyword(s):  
Mechanical Property ◽  
Thermal Stability ◽  
Mechanical Behavior ◽  
Storage Modulus ◽  
Polymer Matrix ◽  
Loss Modulus ◽  
Polyethylene Composite ◽  
Viscoelastic Behaviors ◽  
Thermal Stability Of

ABSTRACTThe effect of processing (shear) time on the mechanical behavior and thermal stability of multiwalled nanotube reinforced polyethylene was investigated. It was observed that the mechanical property (storage modulus, loss modulus) of the composites is process dependant whereas the thermal stability does not. The increase in mechanical behavior is attributed to a stronger interface between the nanotube and the polymer matrix.

Nanocomposite of polypropylene/octadecylamine lamellar-zirconium phosphate: Influence of nanofiller and screw speed

2017 ◽  
Vol 52 (5) ◽  
pp. 701-711 ◽  
Author(s):  
Danielle M Mariano ◽  
Daniela FS Freitas ◽  
Luis C Mendes
Keyword(s):  
Thermal Stability ◽  
Zirconium Phosphate ◽  
Melt Processing ◽  
Screw Speed ◽  
Sem Images ◽  
Crystallinity Degree ◽  
Degradation Temperature ◽  
Diffraction Peaks ◽  
Melting And Crystallization Temperatures ◽  
Melting And Crystallization

Nanocomposite based on polypropylene and octadecylamine-modified lamellar-zirconium phosphate (PP/nano-ZrPOct) was prepared by melt processing. The action of the nanofiller and screw speed on the properties were evaluated. SEM images revealed that at highest screw speed, the higher nano-ZrPOct dispersion was achieved. In WAXD diffractrograms, some nanofiller diffraction peaks disappeared and a new peak was observed at low angle. There was evidence of increase of thermal stability although only discrete increasing in initial degradation temperature has been noticed. Melting and crystallization temperatures were invariable but crystallinity degree was influenced with a decreasing behavior at highest screw speed. The results strongly evidenced that the intercalation of the PP chains inside the nano-ZrPOct galleries and some degree of delamination of the nanofiller platelets have been achieved.

Thermo-Oxidative Degradation of Thick-Walled Rubber Materials Studied by IR-Technique and Computed X-Ray Tomography Scanning

1990 ◽  
Vol 63 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Bengt Mattson ◽  
Bengt Stenberg ◽  
Sture Persson ◽  
Erik Östman
Keyword(s):  
Oxidative Degradation ◽  
Attenuated Total Reflection ◽  
Low Permeability ◽  
Conventional System ◽  
X Ray ◽  
Oxidative Aging ◽  
Aging Properties ◽  
Thermal Stability Of ◽  
Tomography Scanning ◽  
Thermo Oxidative Degradation

Abstract Natural rubber cylinders vulcanized with two different systems, TMTD, which is an efficient vulcanizing system (EV system) and S/CBS, which is a conventional system, have been studied with respect to thermo-oxidative aging gradients, by the ATR-IR-technique (attenuated total-reflection infrared spectroscopy), computed x-ray tomography scanning and swelling. Observed aging processes are dominated by the formation of an oxidized layer whose low permeability to oxygen protects the interior of the material from oxidative aging processes as long as it is intact. The time to the formation of the oxidized layer is the major reason for the differences in the aging gradients. The oxidized layer is formed rapidly in the conventional system, whereas the formation is inhibited by dithiocarbamates in the EV system. Oxygen therefore diffuses into the EV materials, giving deeper oxidative aging than in the conventional materials at the same temperature. The conclusion drawn from the results of this study is that an earlier formation of an oxidized layer is advantageous with respect to thermo-oxidative aging of the bulk. Although it must be stated that, due to the better thermal stability of an EV system and to the poor mechanical properties of an oxidized layer, no objection is here raised to the accepted view that an EV system has superior aging properties.

Thermal Aging Analysis of Rubber Used for Fabric Expansion Joints

2013 ◽  
Vol 807-809 ◽  
pp. 2718-2721
Author(s):  
Li Na Ma ◽  
Yu Zeng Zhao ◽  
Hong Hua Ge ◽  
Kuai Ying Liu
Keyword(s):  
Thermal Stability ◽  
Thermal Aging ◽  
Inert Atmosphere ◽  
Expansion Joints ◽  
Chemical Structures ◽  
Before And After ◽  
The Difference ◽  
Ethylene Propylene Diene Terpolymer ◽  
Thermal Stability Of ◽  
Accelerated Thermal Aging

Several kinds of rubbers used for fabric expansion joints were studied by Thermogravimetric analysis under inert atmosphere before and after artificial accelerated thermal aging. The results showed that because of the difference of the chemical structures, the rubber aging is different. And the thermal stability of Polytetrafluoroethylene (PTFE) was obviously higher than that of other two kinds of rubbers, ethylene-propylene-diene-terpolymer rubber (EPDM) and fluororubber.

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