Peroxide vulcanization of natural rubber. Part II: effect of peroxides and co-agents

2015 ◽  
Vol 35 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Ján Kruželák ◽  
Richard Sýkora ◽  
Ivan Hudec
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
The State ◽  
Rubber Matrix ◽  
Cross Linking ◽  
Type I ◽  
Type Ii ◽  
Rubber Compounds ◽  
Rubber Part

Abstract Four types of peroxides in combination with two types of co-agents were used as cross-linking agents for the preparation of rubber compounds based on natural rubber. The effects of Type I and Type II co-agents on cross-linking and physical-mechanical properties of vulcanizates were investigated. The correlation between mechanisms of the interaction of co-agents with the rubber matrix in relation to the characteristics of tested systems was discussed. The results showed that the Type I co-agent influenced the rate and the state of cure. Physical-mechanical properties were improved by addition of the Type I co-agent. By contrast, the Type II co-agent had no contribution to the rate and state of cure. Moreover, physical-mechanical properties of vulcanizates deteriorated in the presence of this type of co-agent.

Calophyllum Inophyllum Oil as Plasticizer in Natural Rubber Compounds

2009 ◽  
Vol 25 (2) ◽  
pp. 113-128 ◽  
Author(s):  
P. Raju ◽  
V. Nandanan ◽  
Sunil K.N. Kutty
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Thermal Studies ◽  
Calophyllum Inophyllum ◽  
Compression Set ◽  
Peak Rate ◽  
Rubber Compounds ◽  
Cure Time ◽  
Calophyllum Inophyllum Oil ◽  
Control Compound

Mechanical properties and the thermal degradation characteristics of natural rubber compounds with calophyllum inophyllum oil were compared to that of the control compound containing naphthenic oil. The compounds containing calophyllum inophyllum oil showed improved tensile strength, tear strength, modulus, compression set, abrasion resistance and resilience. Cure time was higher than the naphthenic oil mixes. Thermal studies showed an increase of 8 °C in the temperature of initiation of degradation and an increase of 6 °C in temperature at which the peak rate of degradation occurred. The peak rate of degradation was comparable to the control mix containing naphthenic oil.

scholarly journals Thermal analysis of halogenated rubber cured with a new cross-linking system

2019 ◽  
Vol 138 (6) ◽  
pp. 4395-4405 ◽  
Author(s):  
Anna Dziemidkiewicz ◽  
Magdalena Maciejewska ◽  
Martyna Pingot
Keyword(s):  
Mechanical Properties ◽  
Cross Linking ◽  
Curing Agent ◽  
Metal Acetylacetonates ◽  
Damping Properties ◽  
Rubber Blends ◽  
Rubber Compounds ◽  
Curing Agents ◽  
Brominated Butyl Rubber ◽  
Thermal Stability Of

Abstract The aim of this work was to examine the influence of new curing agents proposed for brominated butyl rubber (BIIR) on the cross-linking process of rubber compounds and the thermal behavior of the vulcanizates. Rubber blends that were filled with carbon black and contained acetylacetonates of different transition metals in the presence of triethanolamine (TEOA) as new cross-linking agents were prepared. The performed studies showed that metal acetylacetonates (Me(acac)) are effective cross-linking agents for BIIR, which was confirmed by high values of the torque increment (∆M) and significant cross-linking degree of the vulcanizates (α(T)). The most active curing agent seems to be iron acetylacetonate (Fe(acac)). Its application results in a shorter optimal vulcanization time, lower onset vulcanization temperature and similar vulcanization enthalpy compared to the BIIR cured with a sulfur curing system. The BIIR vulcanizates cured with Me(acac) reveal good mechanical properties with tensile strengths in the range of 9–14 MPa and better damping properties comparing to the sulfur-cured rubber. The proposed curing agents do not significantly affect the thermal stability of the BIIR vulcanizates.

Some discriminatory characteristics of earthquakes near the Kariba, Kremasta, and Koyna artificial lakes

1972 ◽  
Vol 62 (2) ◽  
pp. 493-507 ◽  
Author(s):  
Harsh K. Gupta ◽  
B. K. Rastogi ◽  
Hari Narain
Keyword(s):  
Mechanical Properties ◽  
Time Distribution ◽  
Focal Mechanisms ◽  
Type I ◽  
Type Ii ◽  
B Values ◽  
Artificial Lakes ◽  
Earthquake Sequences ◽  
Frequency Magnitude

abstract The behavior of earthquakes near the artificial lakes at Kariba, Kremasta, and Koyna, where earthquakes of magnitude exceeding 6 have occurred, is examined. Foreshock-aftershock patterns of these earthquake sequences correspond with Mogi's type II model, whereas the normal earthquakes of these regions belong to type I. Three similar relations could be fitted in the time distribution of aftershocks of the main earthquakes. Quite contrary to normal earthquakes, foreshock b values are found to be comparable with the aftershock b values in the frequency-magnitude relations. Focal mechanisms of the largest earthquakes of these sequences have been determined and compared. Dip-slip components of the motion are such that the lakes are situated on the downthrown blocks. These regions are characterized by a volcanic past and the presence of rocks such as limestones and red boles which are easily affected by water. These findings are useful in distinguishing the reservoir-associated earthquakes from normal earthquakes and suggest that the artificial lakes are responsible for changing the mechanical properties of the strata and releasing the accumulated strains.

scholarly journals Detailed Study on the Mechanical Properties and Activation Energy of Natural Rubber/Chloroprene Rubber Blends during Aging Processes

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Quang Nguyen Trong ◽  
Hung Dang Viet ◽  
Linh Nguyen Pham Duy ◽  
Chuong Bui ◽  
Duong Duc La
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Dynamic Loading ◽  
Dynamic Properties ◽  
Activation Energies ◽  
Rubber Matrix ◽  
Static Properties ◽  
Rubber Blends ◽  
Aging Conditions ◽  
Mechanical Aging

Selection of a suitable thermal aging process could render desirable mechanical properties of the rubbers or blended rubbers. In this work, the effect of the aging processes on the mechanical properties and activation energies of natural rubbers (NR) and NR/chloroprene rubbers (CR) blends with low CR contents (5–10%) was investigated. Three aging processes including heat aging (at 110°C for 22 hours), mechanical aging (under dynamic loading to 140% strain for 16000 cycles), and complex aging (heat and mechanical aging) were studied. The results revealed that the compatibility of CR in natural rubber matrix had a significant effect on the dynamic properties of the blended rubber and negligible effect on the static properties. The changes in activation energies of the blended rubber during aging processes were calculated using Arrhenius relation. The calculated changes (ΔUc, ΔUd, and ΔUT) in activation energies were consistent with the results of mechanical properties of the blended rubber. Interestingly, the change in activation energies using complex aging conditions (ΔUc) was mostly equal to the total changes in activation energies calculated separately from heat aging (ΔUT) and mechanical aging (ΔUd) conditions. This indicates that, in complex aging conditions, the heat and dynamic loading factors act independently on the properties of the blended rubber.

scholarly journals Physiological and Clinical Significance of Disordered Cross-Linking of Fibrin

1977 ◽  
Author(s):  
L. Lorand
Keyword(s):  
Class Ii ◽  
Class I ◽  
Cross Linking ◽  
Type I ◽  
Type Ii ◽  
Zymogen Activation ◽  
Primary Defect ◽  
Plasma Clot ◽  
Autoimmune Antibodies ◽  
Hereditary Disorders

Disorders of fibrin stabilization are hemorrhagic conditions in which the patient’s plasma clot is lacking in inter-fibrin γ-glutamyl-ε-lysine isopeptide linkages. The primary defect occurs either because no fibrinoligase (FXIIIa) activity can be generated or because the enzyme cannot act on fibrin in the patient’s plasma. Distinction is made between hereditary disorders (Class I) and those appearing later in life because of an acquired inhibitor (Class II) directed against one of the steps on the pathway of fibrin stabilization: Of the genetic deficiencies (Class I), Type I is characterized by a lack of zymogen activity in plasma and Type II by the unreactivity of the cross-linking sites of the patient’s fibrin [“dysfibrin(ogen)emias”] towards fibrinoligase.There are three varieties of Class II abnormalities. In Type I, the acquired inhibitor interferes with zymogen activation. Type II inhibitors affect transamidation by competing against fibrin for the enzyme. The Type III inhibitor combines with fibrin rendering it unreactive towards fibrinoligase. The Type I and III inhibitors appear to be autoimmune antibodies.(Ann. N. Y. Acad. Sei., 202, 6, 1972).Differential diagnostic criteria for this family of molecular disorders will be discussed.

Characterization of Snap-On Calf Nipple Product and Development of its Compound Formulation Based on Natural Rubber

2017 ◽  
Vol 744 ◽  
pp. 282-287
Author(s):  
Sarawut Prasertsri ◽  
Sansanee Srichan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Calcium Carbonate ◽  
Carbon Black ◽  
Natural Rubber ◽  
Soxhlet Extraction ◽  
Rubber Compound ◽  
Rubber Compounds ◽  
Rubber Component

This research aimed to develop the formulation of natural rubber filled with carbon black, silica and calcium carbonate for rubber calf nipple application. The reverse engineering was performed on the calf nipple product to analyze the rubber type and component by using Soxhlet extraction, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques. Furthermore, mechanical properties were examined to act as benchmark for the rubber compound design. The results showed that rubber component in the nipple product was natural rubber, whereas two filler types revealed as carbon black and calcium carbonate with 10 and 35 of the total weight. In addition, rubber nipple showed the hardness of 46±1 Shore A and tensile strength of 5.3±0.60 MPa. From the investigation of the properties of developed rubber compounds in this work, it was found that the mechanical properties depended on type and content of filler. The required mechanical properties of vulcanizates were achieved at 20 phr of carbon black (N330), 20 phr of silica and 120 phr of calcium carbonate.

Properties of Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

2015 ◽  
Vol 1109 ◽  
pp. 195-199 ◽  
Author(s):  
Abd Aziz Azira ◽  
Dayang Habibah Abangismawi I. Hassim ◽  
D. Verasamy ◽  
Abu Bakar Suriani ◽  
M. Rusop
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Natural Rubber ◽  
Considerable Increase ◽  
Physical And Mechanical Properties ◽  
Rubber Matrix ◽  
Rubber Composites ◽  
Transmission Electron ◽  
Maximum Conductivity ◽  
Polymer Latex

In order to achieve improvements in the performance of rubber materials, the development of carbon nanotube (CNT)-reinforced rubber composites was attempted. The CNT/epoxidised natural rubber (ENR) nanocomposite was prepared through latex technology. Physical and mechanical properties of the CNT/ENR nanocomposites were characterized in contrast to the carbon black (CB)/ENR composite. The dispersion of the CNTs in the rubber matrix and interfacial bonding between them were rather good; monitored transmission electron microscopy and scanning electron microscopy. The mechanical properties of the CNT-reinforced ENR showed a considerable increase compared to the neat ENR and traditional CB/ENR composite. The storage modulus of the CNT/ENR nanocomposites greatly exceeds that of neat ENR and CB/ENR composites and a maximum conductivity of about 1 S m-1 can be achieved. The approach presented can be adapted to other CNT/polymer latex systems.

scholarly journals Use of waste materials in rubber matrix

2018 ◽  
Vol 157 ◽  
pp. 07009 ◽  
Author(s):  
Mariana Pajtášová ◽  
Zuzana Mičicová ◽  
Darina Ondrušová ◽  
Slavomíra Božeková ◽  
Róbert Janík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Loss Modulus ◽  
Rolling Resistance ◽  
Dynamic Mechanical Properties ◽  
Waste Materials ◽  
Partial Replacement ◽  
Rubber Matrix ◽  
Loss Angle ◽  
Rubber Compounds ◽  
Tan Δ

The presented paper deals with the use of waste materials as ecological fillers into rubber matrix. Waste materials were used as partial replacement of the commercial filler – carbon black, designated as N339. These prepared rubber compounds were characterized on the basis of the rheology and vulcanization characteristics – minimum torque (ML), maximum torque (MH), optimum time of vulcanization (t(c90)), processing safety of compound (ts), rate coefficient of vulcanization (Rv). In the case of the prepared vulcanizates, physical-mechanical properties (tensile strength, tensibility and hardness) and dynamic-mechanical properties (storage modulus, loss modulus, loss angle tan δ) were investigated. Using the dependency of loss angle on temperature, the selected properties for tyre tread vulcanizates were evaluated, including traction on snow and ice, traction on the wet surface and rolling resistance.

Sign in / Sign up

Export Citation Format

Share Document