Dynamic Testing of Automotive Rubber Parts by the Resonant Beam Tester. Effect of Polymer, Deflection, Age, and Temperature on Dynamic Rate

Abstract When the recipe is basically the same, different polymers differ in dynamic rate and damping. Ethylene—propylene terpolymer, SBR, neoprene, and butyl gave higher dynamic rate and higher damping than natural rubber, polyisoprene, and the blend of polyisoprene and cis 1,4-polybutadiene. The lowest dynamic rate and lowest damping is obtained with polyisoprene. At room temperature, polymers having the highest damping also have the largest ratio of dynamic to static rate. One cannot predict the effect of temperature on dynamic rate by measuring static rate at these temperatures. Increase in temperature lowers dynamic rate, decrease in temperature increases it. This effect was least with a blend of polyisoprene and cis 1,4-polybutadiene, closely followed by polyisoprene, and natural rubber. The largest change was with butyl. Dynamic rate increases with time after cure. After 26 hr, dynamic rate is a function of the logarithm of time. This effect is least with polyisoprene. Natural rubber, SBR, EPT, neoprene and a blend of polyisoprene with cis 1,4-polybutadiene all follow Equation (1). Butyl has, by far, the greatest change in dynamic rate with time. Reducing the deflection from 0.012 in. to 0.004 in. linearly increased the dynamic rate. Times of vibration between 2 minutes and 60 minutes at room temperature had no effect on dynamic rate.

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Solubility and Mobility of Sulfur in Ethylene-Propylene and Ethylene-Butene-1 Copolymers

Rubber Chemistry and Technology ◽

10.5254/1.3539596 ◽

1963 ◽

Vol 36 (3) ◽

pp. 660-667

Author(s):

L. Baldi ◽

R. Zannetti

Keyword(s):

Natural Rubber ◽

Effect Of Temperature ◽

Copolymer Composition ◽

Ethylene Propylene ◽

Vulcanization Process

Abstract Solubility and mobility of sulfur in copolymers of ethylene/propylene and ethylene/butene-1 were determined, using S 35 according to the method developed by Auerbach and Gehman for natural rubber and certain polymers and copolymers possessing elastomeric properties. We took into consideration the effect of temperature and copolymer composition, both on the solubility and on the mobility of the sulfur. Also examined was the effect of the migration of sulfur to the surface of the vulcanized product. The results are discussed in relation to the characteristics of the vulcanization process.

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Solvent-assisted osmium staining of butyl acrylate and ethylene-propylene-diene in a styrene acrylonitrile matrix

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150332 ◽

1993 ◽

Vol 51 ◽

pp. 900-901 ◽

Cited By ~ 1

Author(s):

Gudrun A. Hutchins

Keyword(s):

Butyl Acrylate ◽

Room Temperature ◽

Osmium Tetroxide ◽

Staining Procedure ◽

Reactive Site ◽

Ethylene Propylene ◽

Minimal Distortion ◽

Styrene Acrylonitrile ◽

Engineering Polymers ◽

Effective Reaction

In order to optimize the toughening effect of elastomers in engineering polymers, it is necessary to characterize the size, morphology and dispersion of the specific elastomer within the polymer matrix. For unsaturated elastomers such as butadiene or isoprene, staining with osmium tetroxide is a well established procedure. The residual carbon-carbon double bond in these materials is the reactive site and forms a 1,2-dilato complex with the OsO4. Incorporation of osmium tetroxide into the elastomer not only produces sufficient contrast for TEM, but also crosslinks the elastomer sufficiently so that ultramicrotomy can be accomplished at room temperature with minimal distortion.Blends containing saturated elastomers such as butyl acrylate (BA) and ethylene propylene diene monomer (EPDM) cannot be stained directly with OsO4 because effective reaction sites such as C=C or -NH2 are not available in sufficient number. If additional reaction sites can be introduced selectively into the elastomer by a chemical reaction or the absorption of a solvent, a modified, two-step osmium staining procedure is possible.

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Effect of Temperature on ADP-Induced Platelet Aggregation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647758 ◽

1973 ◽

Vol 29 (01) ◽

pp. 183-189

Author(s):

C. A Praga ◽

E. M Pogliani

Keyword(s):

Platelet Aggregation ◽

Incubation Period ◽

Room Temperature ◽

Important Variable ◽

Practical Significance ◽

Effect Of Temperature ◽

Induce Platelet Aggregation ◽

Cuvette Holder ◽

Exact Temperature

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.

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The effect of polyhedral oligomeric silsesquioxanes (POSSs) incorporation in ethylene-propylene-diene-terpolymer (EPDM): a thermal study

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-021-10994-x ◽

2021 ◽

Author(s):

Ignazio Blanco ◽

Traian Zaharescu

Keyword(s):

Room Temperature ◽

Thermal Characterization ◽

Polyhedral Oligomeric Silsesquioxanes ◽

Dsc Analysis ◽

Γ Irradiation ◽

Scanning Calorimetry ◽

Ethylene Propylene ◽

Oligomeric Silsesquioxane ◽

Ethylene Propylene Diene Terpolymer ◽

Dynamic Heating

AbstractA series of ethylene-propylene-diene-terpolymer (EPDM)/polyhedral oligomeric silsesquioxane (POSS) composites at different percentage of POSS were prepared and subjected to γ-irradiation. Both irradiated and non-irradiated EPDM and composites were investigated by the means of thermal analysis to verify if the presence of POSS molecules is able to reduce the oxidation level of free radicals generated during the degradation and to evaluate the effects of the irradiation. EPDM composites at 1, 3 and 5 mass% of POSS were thus degraded in a thermogravimetric (TG) balance in dynamic heating conditions (25–700 °C), in both inert and oxidative atmosphere by flowing nitrogen and air respectively. Thermal characterization was then completed by carrying out Differential Scanning Calorimetry (DSC) analysis from sub-ambient to better highlight the melting of the polymer and polymer composites occurring just above the room temperature. FTIR spectroscopy was also performed for the prepared samples to check the presence of the molecular filler in the composites and for the TG’s residue at 700 °C, in order to evaluate its nature. DSC and TGA parameters were detected and discussed to have information about the effect of the degradation’s environment, the effect of irradiation on polymer stabilization and the effect of POSS content in the polymer matrix.

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Green Biosynthesis of Silver Nanoparticles Using Leaf Extract of Carissa carandas L. and Their Antioxidant and Antimicrobial Activity against Human Pathogenic Bacteria

Biomolecules ◽

10.3390/biom11020299 ◽

2021 ◽

Vol 11 (2) ◽

pp. 299

Author(s):

Reetika Singh ◽

Christophe Hano ◽

Gopal Nath ◽

Bechan Sharma

Keyword(s):

Silver Nanoparticles ◽

Pathogenic Bacteria ◽

Leaf Extract ◽

Room Temperature ◽

Xrd Analysis ◽

Antibacterial Activities ◽

Effect Of Temperature ◽

Human Pathogenic Bacteria ◽

Carissa Carandas ◽

Antioxidant And Antimicrobial Activity

Carissa carandas L. is traditionally used as antibacterial medicine and accumulates many antioxidant phytochemicals. Here, we expand this traditional usage with the green biosynthesis of silver nanoparticles (AgNPs) achieved using a Carissa carandas L. leaf extract as a reducing and capping agent. The green synthesis of AgNPs reaction was carried out using 1mM silver nitrate and leaf extract. The effect of temperature on the synthesis of AgNPs was examined using room temperature (25 °C) and 60 °C. The silver nanoparticles were formed in one hour by stirring at room temperature. In this case, a yellowish brown colour was developed. The successful formation of silver nanoparticles was confirmed by UV–Vis, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis. The characteristic peaks of the UV-vis spectrum and XRD confirmed the synthesis of AgNPs. The biosynthesised AgNPs showed potential antioxidant activity through DPPH assay. These AgNPs also exhibited potential antibacterial activity against human pathogenic bacteria. The results were compared with the antioxidant and antibacterial activities of the plant extract, and clearly suggest that the green biosynthesized AgNPs can constitute an effective antioxidant and antibacterial agent.

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Color and Antioxidant Changes in Various Natural Rubber Processes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.754-755.230 ◽

2015 ◽

Vol 754-755 ◽

pp. 230-234 ◽

Cited By ~ 1

Author(s):

Suwimon Siriwong ◽

Adisai Rungvichaniwat ◽

Pairote Klinpituksa ◽

Khalid Hamid Musa ◽

Aminah Abdullah

Keyword(s):

Acetic Acid ◽

Natural Rubber ◽

Retention Index ◽

Total Phenolic Content ◽

Room Temperature ◽

Phenolic Content ◽

Total Phenolic ◽

Lovibond Colorimeter

Fresh field natural rubber was coagulated by acetic acid, soaked in water at room temperature (WRT) or 70°C (W70) for 1 hr, and then dried in an oven at 40°C. Non-soaked natural rubber samples (NoW) served as a control. Two grades of natural rubber, namely air-dry sheet (ADS) and ribbed smoked sheet No.3 (RSS3) derived from the same latex, were also investigated. All dry rubber samples were characterized with Lovibond colorimeter according to ASTM D3157, as well as with a HunterLab spectrophotometer. Furthermore, all the dry rubber samples were dissolved in a chloroform:methanol mixture (4:1 v:v). The rubber was then precipitated out of the solution with methanol, and the remaining solution was quantitatively analyzed for total phenolic content (TPC). The plasticity retention index (PRI) was determined for all the dried rubber samples according to ASTM D3194. It was found that WRT, W70 and ADS were similar in lightness L*, while RSS3 had the lowest L*. W70 had the lowest redness a*, which increased in the order WRT, NoW, RSS3 and ADS. W70 also had the lowest yellowness b*, which increased in the order RSS3, NoW and WRT and ADS. Moreover, TPC was the lowest for the W70 sample, increasing in the order ADS, WRT, NoW and RSS3. The PRI was highest for W70, and decreased in the order WRT, RSS3, NoW and ADS. All of the PRI values observed were comparatively high relative to blocked standard Thai rubber 20 (STR20).

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