Effect of Curing Temperature on the Technical Properties of Nitrile Rubber and Carboxylated Nitrile Rubber

1980 ◽  
Vol 53 (1) ◽  
pp. 107-115 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. K. De
Keyword(s):  
Metal Ion ◽  
Crosslink Density ◽  
Nitrile Rubber ◽  
Curing Temperature ◽  
Aging Studies ◽  
Aging Resistance ◽  
Technical Properties ◽  
Low Sulfur ◽  
Better Than ◽  
Sulfur Donor

Abstract In a mixed crosslink system (sulfur and metal carboxylate) of XNBR vulcanizate, the variations of the proportions of curatives (low sulfur/high accelerator or high sulfur/low accelerator) have little effect on the vulcanizate properties. But aging studies indicate that the metal ion crosslinks are modified in the presence of a sulfur vulcanizing system. NBR vulcanizates with a comparable recipe have less crosslink density than the corresponding XNBR ones. In general, the technical properties and aging resistance of mixed crosslink systems using ZnO2 and sulfur donor-sulfur are better than the NBR vulcanizates. Increase of curing temperature does not always lower the technical properties of XNBR and NBR vulcanizates. Addition of XNBR to NBR in XNBR-NBR blends lowers most of the technical properties, possibly due to different vulcanization characteristics.

scholarly journals Plasticization Effect of Bio-Based Plasticizers from Soybean Oil for Tire Tread Rubber

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 623 ◽  
Author(s):  
Haoshu Xu ◽  
Tao Fan ◽  
Neng Ye ◽  
Weidong Wu ◽  
Daye Huang ◽  
...  
Keyword(s):  
Soybean Oil ◽  
Crosslink Density ◽  
Plasticization Effect ◽  
Additive Content ◽  
Resistance Property ◽  
Modified Soybean Oil ◽  
Aging Resistance ◽  
Harmful Effects ◽  
Tread Rubber ◽  
Better Than

Modified soybean oil (MSO) is synthesized from soybean oil (SO) and sulfur, aiming to reduce the double bond quantity of SO and avoid harmful effects on the crosslink density and mechanical properties of rubber. MSO modified with different weight percentages of sulfur is then used to plasticize tire tread rubber (TR). It is found that the crosslink density and modulus of MSO- plasticized rubber are significantly improved compared with that of SO-plasticized TR. MSO modified with 6 wt % sulfur (MSO-6%) exhibits the best plasticization effect on TR, thus, the plasticization effect of MSO-6% on TR was further studied by adjusting its additive content. Thereafter, the Mooney viscosity, Payne effect, mechanical property of different amount of MSO-6% plasticized TR are studied to investigate their plasticization effect. At the same additive content of plasticizer, the plasticization effect of MSO-6% and a commonly used aromatic hydrocarbon plasticizer (AO) is compared to determine the potential application of MSO on tire tread rubber. It is found MSO shows similar plasticization effect on TR compared with AO. More important, the aging resistance property and wear resistance property of MSO-6% plasticized rubber are better than those of AO-plasticized rubber. Therefore, MSO-6% is a promising bio-based plasticizer for tire tread rubber.

Correlation between Curing Temperature and the Properties of Conductive Composites

2013 ◽  
Vol 750-752 ◽  
pp. 119-122 ◽  
Author(s):  
Xiao Ya Wang ◽  
Zhi Dong Xia ◽  
Zhe Li
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Crosslink Density ◽  
Fracture Morphology ◽  
Curing Temperature ◽  
Tensile Fracture ◽  
Elongation At Break ◽  
Conductive Composites ◽  
The Stability ◽  
Better Than

This study was carried out to discuss the influence of curing temperature on the performance of conductive composites filled with nickel-coated graphite (NCG). The electrical conductivity, crosslink density, mechanical properties and tensile fracture morphology have been investigated. The results indicated that curing temperature had great impact on the electrical conductivity and mechanical properties. Voluem resistivity decreased from 43.1 to 0.08 ohm-cm at 125°C-205°C, and the reason was discussed in light of formation and break of the conductive network in the composites. The stability of SR-NCG cured at 165°C-205°C were also better than those cured at other curing temperature. Besides, tensile strength increased from 2.41 to 7.19Mpa at 125°C-225°C, elongation at break have a 56% increase, and Shore A hardness also incresed from 74 to 82.

Kinetics of Crosslinking and Network Changes in Natural Rubber Vulcanizates with a Dithiodimorpholine Based Accelerator System

1980 ◽  
Vol 53 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. K. De
Keyword(s):  
Natural Rubber ◽  
Rate Constants ◽  
Crosslink Density ◽  
Curing Temperature ◽  
Side Reactions ◽  
Filler Surface ◽  
Natural Rubber Vulcanizates ◽  
Kinetics Of ◽  
Accelerator System

Abstract Kinetics of crosslinking and network changes in unfilled and filled natural rubber vulcanizates with a dithiodimorpholine based accelerator system have been studied at 150° and 180°C. Results show that addition of HAF black enhances the polysulfidic crosslinks as well as the total crosslinks. This has been explained with the help of Coran's model wherein HAK black increases the rate constants. It is likely that the filler surface prevents desulfuration and undesirable side reactions involving the crosslink precursors. Increase of curing temperature by 30°C lowers the total crosslink density and increases the sulfur inefficiency.

scholarly journals Characterization of Complexes Synthesized Using Schiff Base Ligands and Their Screening for Toxicity Two Fungal and One Bacterial Species on Rice Pathogens

2014 ◽  
Vol 2014 ◽  
pp. 1-22 ◽  
Author(s):  
T. Mangamamba ◽  
M. C. Ganorkar ◽  
G. Swarnabala
Keyword(s):  
Metal Ion ◽  
Physiological Activity ◽  
Bacterial Species ◽  
Atomic Weight ◽  
Fungal Species ◽  
Schiff Base Ligands ◽  
Rice Pathogens ◽  
Complexes With Metal Ions ◽  
Better Than

Coordination complexes with metal ions Cu(II), Ni(II), Co(II), Fe(III), Mn(II), Cr(III), and VO(II) with six ligands formed by condensation products using azides and aldehydes or ketones are characterized. Both the ligands and the complexes synthesized are characterized by C, H, N, Cl and metal analyses, IR, UV-Vis, TGA, and magnetic susceptibility for tentative structure proposal. Several of them are screened for their toxicity (i.e., physiological activity) against fungal species Rhizoctonia solani and Acrocylindrium oryzae and a bacterium, Xanthomonas oryzae on rice pathogens. The study shows that the observed physiological activity is enhanced for the metal complexes as compared to the simple metal salts or ligands, except in the case of L3 or HAEP ligand, where the free –OH and –NH2 groups on the ligand seemed to have inhibited the activity. It is also observed that the order of activity has a dependence on the increased atomic weight of the metal ion in use. In some cases, especially the VO(II) complexes, they are found to be better than the standards in use, both for the fungicides and for the bactericide.

New Accelerators for Vulcanization of Rubber—Part III: Synthesis, Characterization, and Evaluation of Some 2-Mercaptobenzimidazole Derivatives

1985 ◽  
Vol 58 (4) ◽  
pp. 713-727 ◽  
Author(s):  
D. Pal ◽  
A. Khamrai ◽  
B. Adhikari ◽  
T. Dutta ◽  
Mrinal M. Maiti ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Antioxidant Properties ◽  
Antioxidant Compounds ◽  
Dual Function ◽  
Cure Characteristics ◽  
Aging Resistance ◽  
Rubber Part ◽  
Derivatives Of ◽  
Better Than

Abstract Five derivatives of 2-mercaptobenzimidazole containing S—N bonds have been synthesized and evaluated for their action as accelerator-antioxidant in NR gum stocks. All these compounds exhibit varying degree of accelerating efficiency; some of them, viz. MBSTP, MBSPT, and MBDSPT, offer excellent cure characteristics and vulcanizate properties comparable to some of the best commercially available curatives such as CPTD. Substitution at the N or S atom of the MB molecule does not affect adversely its antioxidant properties; rather, an improvement in aging resistance has been achieved. The degree and nature of substitution play an important role in the antioxidation properties of these MB derivatives. Thus, disubstitution offers better antioxidation characteristics than monosubstitution, and the latter, in turn, is better than unsubstituted MB. Some discussion on correlation of reactivities of these MB derivatives and their cure synergism with CPTD have been reported. It was observed that these new accelerator—antioxidant compounds show very little cure synergism with CPTD but do show promise as dual-function curatives for natural rubber.

The Influence of Accelerators on EPDM Vulcanizate Structure

1972 ◽  
Vol 45 (5) ◽  
pp. 1348-1365 ◽  
Author(s):  
F. P. Baldwin
Keyword(s):  
Low Temperature ◽  
Crosslink Density ◽  
Low Rank ◽  
Type Synthesis ◽  
Cure Rate ◽  
High Concentration ◽  
Other Information ◽  
The Stability ◽  
Low Sulfur ◽  
Vulcanization Process

Abstract This study of vulcanization has revealed that in low unsaturation EPDM elastomers prepared with ethylidenenorbornene— 1. Stearic acid can be a useful additive for vulcanization. Increasing concentration in the range 0-4 phr leads to faster curing and reduced polysulfidic crosslink concentration at a given crosslink density. 2. Low sulfur and low sulfur/accelerator ratio and/or prolonged curing times are required to generate vulcanizates containing low percentages of polysulfidic crosslinks. 3. At identical crosslink densities, high temperature cures display a lower level of polysulfidic crosslinks than low temperature cures. However, olefin utilization in crosslinking is generally better with low temperature curing. 4. At high sulfur levels, variations in crosslink type distribution resulting from accelerator changes tend to disappear. 5. Mixed acceleration—a dialkylthiocarbamic acid derivative and an accelerator having the benzothiazolylthio radical—appear best suited for the combination of maximizing cure rate and producing stable (lower sulfur rank) crosslinks. Taken together with other information, the results of this study lead to the suggestion that: 6. The stability of the basic accelerator nucleus is influential both on cure rate and on the ability to generate stable crosslinks. 7. The exact structure and concentration of the olefinic moieties present in the polymer have at least as much bearing on the detailed outcome of the vulcanization process as do changes in accelerator. 8. A useful accelerator for these rubbers resulting in the production of vulcanizates containing a high concentration of low rank sulfur crosslink might derive from a MBT type synthesis based on a properly ringalkylated aniline. 9. Some effort devoted to the study of chemicals which may not accelerate crosslinking but could participate in the crosslink shortening process would appear worthwhile.

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