Investigation of Un-Vulcanized Natural Rubber by Means of Temperature Scanning Stress Relaxation Measurements

2013 ◽  
Vol 718-720 ◽  
pp. 117-123 ◽  
Author(s):  
Miao Wu ◽  
Michael Heinz ◽  
Norbert Vennemann
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
Branch Points ◽  
Relaxation Spectra ◽  
Green Strength ◽  
Testing Method ◽  
Relaxation Measurements ◽  
Different Types ◽  
Temperature Scanning

Two different types of un-vulcanized natural rubber, air dried sheets (ADS) and SVR-3L block rubber, were investigated by a new testing method and the results are compared with other mechanical properties. It was found that green strength is strongly reduced if the sample is ther­mal­ly treated before testing. Presumably, the decrease of strength is caused by a decrease of branch points, mainly composed of phospholipids, which are linked to the a - terminal groups of the rubber molecules. The existence of two different types of branch points is indicated by relaxation spectra, obtained from temperature scanning stress relaxation (TSSR) measurements.

Determination of Crosslink Density and Network Structure of NR Vulcanizates by Means of TSSR

2013 ◽  
Vol 844 ◽  
pp. 482-485 ◽  
Author(s):  
Norbert Vennemann ◽  
Christina Schwarze ◽  
Claudia Kummerlöwe
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Network Structure ◽  
Crosslink Density ◽  
Relaxation Spectrum ◽  
Strong Impact ◽  
Relaxation Spectra ◽  
Peak Separation ◽  
Temperature Scanning

Unfilled vulcanizates based on natural rubber (NR) were investigated by temperature scanning stress relaxation (TSSR) measurements. Different sulfur based cure systems, i.e. conventional (CV), semi-efficient (SEV) and efficient (EV) vulcanization system, were used to prepare the vulcanizates. It was found that sulfur/accelerator - ratio has a strong impact on the shape of the relaxation spectrum, deduced from TSSR measurements. By deconvolution of the relaxation spectra, peak separation was performed and 3 different peaks were found in case of CV - cured samples. In contrast, only a single peak was found, in case of the EV-cured sample. After thiolamine treatment the shape of the relaxation spectra altered significantly in case of the CV-cured sample whereas the spectra of the SEV-and EV-cured sample exhibited only slight differences. Additionally, the crosslink density of the samples decreased after thiolamine treatment. This is due to selective cleavage of polysulfidic crosslinks. It has been concluded, that the significant peak in the relaxation spectrum at about 120 °C can be attributed to the cleavage of polysulfidic crosslinks. Furthermore, a linear relationship between the percentage of polysulfidic crosslinks and the sulfur/accelerator - ratio is assumed.

Influence of the Type of Alkylamine Organic Modifiers on Thermal Mechanical Behavior and other Related Properties of Natural Rubber/Clay Nanocomposites

2013 ◽  
Vol 844 ◽  
pp. 217-220 ◽  
Author(s):  
Uraiwan Sookyung ◽  
Woothichai Thaijaroen ◽  
Norbert Vennemann ◽  
Charoen Nakason
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
The Other ◽  
Clay Nanocomposites ◽  
Organic Modifier ◽  
Organic Modifiers ◽  
Different Types ◽  
Thermal Stability Of

Sodium-montmorillonite (Na-MMT) nanoclay was modified with different types of alkylamine organic modifier including primary and quaternary alkylamines. Influence types of alkylamine on properties of natural rubber/clay nanocomposites was investigated. It was found that organoclays caused improvement of mechanical properties of natural rubber, and accelerated vulcanization reaction with higher degree of crosslinking. In addition, organoclay modified with quaternary alkylamine showed significance cure reversion phenomenon which caused reduction of thermal stability. On the other hand, primary alkylamine modified nanoclay caused improvement of thermal stability of natural rubber. Moreover, stress relaxation was observed at the melting temperature of the modifying agent.

scholarly journals Mechanical Properties of Natural Rubber Nanocomposites Filled with Thermally Treated Attapulgite

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Jihu Wang ◽  
Dajun Chen
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Curing Process ◽  
Immiscible Blends ◽  
Microscope Images ◽  
Different Types ◽  
Modified Attapulgite ◽  
Rubber Nanocomposites ◽  
Thermal Stability Of ◽  
Scanning Electron

Natural rubber (NR) nanocomposites were prepared in a double-roller plasticator mixer with purified attapulgite (PAT) or modified attapulgite, which was treated at 450°C (PAT-450) and 850°C (PAT-850) for two hours. The structures of the pristine, purified, and modified attapulgite were characterized by FTIR, TEM, XRD, and BET. The results indicated that the structure of attapulgite changed with the increased temperature. The effects of the PAT treatment and content on the mechanical properties of the NR nanocomposites were also investigated. The results showed that AT increased curing process of natural rubber. A significant improvement in the tensile strength, wearability, and solvent resistance of the nanocomposites was observed with the addition of different types of attapulgite as compared to those of pure NR. Scanning electron microscope images showed that the filler was located at the interface, which induced compatibilization in the immiscible blends. Thermogravimetric analysis revealed a significant improvement in the thermal stability of the NR/PAT nanocomposites.

scholarly journals Influence of Filler from a Renewable Resource and Silane Coupling Agent on the Properties of Epoxidized Natural Rubber Vulcanizates

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Wiphawadee Pongdong ◽  
Charoen Nakason ◽  
Claudia Kummerlöwe ◽  
Norbert Vennemann
Keyword(s):  
Mechanical Properties ◽  
Metal Oxide ◽  
Natural Rubber ◽  
Elevated Temperatures ◽  
Polymer Network ◽  
Renewable Resource ◽  
Dynamic Mechanical Properties ◽  
Epoxidized Natural Rubber ◽  
Cure Characteristics ◽  
Temperature Scanning

Rice husk ash (RHA) was used as a reinforcing filler in epoxidized natural rubber (ENR) with various loading levels (0, 10, 20, and 30 phr), and silica filled ENR was also studied for comparison. The effects of RHA content on cure characteristics, mechanical properties, dynamic mechanical properties, and thermoelastic behavior of the filled ENR composites were investigated. It was found that the incorporation of RHA significantly affected the cure characteristics and mechanical properties. That is, the incorporation of RHA caused faster curing reactions and increased Young’s modulus and tensile strength relative to the unfilled compound. This might be attributed to the metal oxide impurities in RHA that enhance the crosslinking reactions, thus increasing the crosslink density. Further improvements in the curing behavior and the mechanical properties of the filled composites were achieved byin situsilanization with bis(triethoxysilylpropyl) tetrasulfide (Si69). It was found that the rubber-filler interactions reinforced the composites. This was indicated by the decreased damping characteristic(tan ⁡δ)and the other changes in the mechanical properties. Furthermore, the ENR composites with Si69 had improved filler dispersion. Temperature scanning stress relaxation (TSSR) results suggest that the metal oxide impurities in RHA promote degradation of the polymer network at elevated temperatures.

Investigation of modified SEBS-based thermoplastic elastomers by temperature scanning stress relaxation measurements

2005 ◽  
Vol 45 (11) ◽  
pp. 1498-1507 ◽  
Author(s):  
Aron Barbe ◽  
Klaus Bökamp ◽  
Claudia Kummerlöwe ◽  
Henner Sollmann ◽  
Norbert Vennemann ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Thermoplastic Elastomers ◽  
Relaxation Measurements ◽  
Temperature Scanning

scholarly journals A Clinically Relevant Method of Quantifying the Mechanical Properties of RockTape® Kinesiology Tape at Different Elongation Lengths

2021 ◽  
Vol 30 (1) ◽  
pp. 173-176
Author(s):  
Scott W. Cheatham ◽  
Russell Baker
Keyword(s):  
Mechanical Properties ◽  
Young Modulus ◽  
Future Research ◽  
Sports Performance ◽  
Testing Method ◽  
Different Types ◽  
Novel Method ◽  
Kinesiology Tape ◽  
Validation Research ◽  
University Laboratory

Context: Kinesiology tape (KT) is a therapeutic intervention used to treat different musculoskeletal conditions and to enhance sports performance. The evidence is inconclusive, with researchers attributing the variable outcomes to different manufactured KT used in the research. Researchers have begun to measure and document the mechanical properties of different brands, using machines versus professionals. This prevents a clear translation to clinical practice, as it may be difficult to reproduce outcomes. There is a need to measure the mechanical properties of KT using more clinically relevant methodology. Objective: The purpose was to document a clinically relevant method of measuring the mechanical properties of 2 different types of precut RockTape® tape at common elongation lengths and to establish the methodology for future validation research on this testing method. Design: Controlled laboratory study. Setting: University laboratory. Participants: One researcher conducted all measurements. Procedures: Each tape was measured at 3 elongation lengths with a force gauge. Main Outcome Measures: Force, stress, and Young modulus. Results: The RockTape® 2 and RockTape® 3 elongation force were 25% = 2.27 (0.21) and 2.12 (0.26) N, 50% = 6.51 (0.27) and 5.93 (0.20) N, and 75% = 30.13 (0.63) and 21.23 (0.41) N. The stress values for the RockTape® 2 and RockTape® 3 were 25% = 0.88 (0.05) and 0.82 (0.03) kPa, 50% = 2.52 (0.03) and 2.29 (0.01) kPa, and 75% = 11.67 (0.04) and 8.23 (0.02) kPa. The Young modulus values for the RockTape® 2 and RockTape® 3 were 25% = 3.51 (0.00) and 3.29 (0.00) kPa, 50% = 5.04 (0.00) and 4.60 (0.00) kPa, and 75% = 15.57 (0.00) and 10.96 (0.00) kPa. Conclusion: This investigation documented a novel method of measuring the mechanical properties of 2 types of RockTape® KT. Future research should attempt to validate these testing methods.

Stress Relaxation during the Thermal Oxidation of Vulcanized Natural Rubber

1960 ◽  
Vol 33 (2) ◽  
pp. 423-432
Author(s):  
J. R. Dunn ◽  
J. Scanlan ◽  
W. F. Watson
Keyword(s):  
Free Radical ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
Thermal Aging ◽  
Elevated Temperatures ◽  
The Other ◽  
Tetramethylthiuram Disulfide ◽  
Oxidative Aging ◽  
Relaxation Measurements ◽  
Cross Links

Abstract The photoinitiated oxidative aging of peroxide vulcanized natural rubber (which contains only carbon-carbon cross-links) was found by stress relaxation measurements to be autocatalytic and to be sensitive to the presence of free radical retarders and catalysts. Similar behavior would be expected in thermal aging. However, earlier work in these laboratories indicated that the thermal aging of peroxide vulcanizates was not autocatalytic. Because of this discrepancy the stress relaxation of peroxide vulcanizates at elevated temperatures has now been reinvestigated and the study has been extended to include also the aging of the other types of networks which are produced on vulcanization by tetramethylthiuram disulfide in the absence of sulfur, by sulfenamide-sulfur, and by sulfur alone.

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