Influence of Accelerator Residues on Age Resistance of Vulcanizates

1960 ◽  
Vol 33 (2) ◽  
pp. 490-501
Author(s):  
Z. T. Ossefort
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Network Structure ◽  
Dual Process ◽  
Curing Process ◽  
Active Inhibitor ◽  
The Stability ◽  
Prime Function ◽  
Better Than

Abstract It has been shown that the age resistance of elastomeric vulcanizates is influenced to a very marked degree by residues formed in situ in the vulcanizate during the curing process. By a dual process of removal of these residues and incorporation of selected ingredients subsequent to vulcanization, it has been shown that age resistance (as measured by accelerated oven-aging tests at 212° F) in rubbers cured by sulfur and/or sulfur bearing accelerators, is a prime function of these residues and nearly independent of the stability of the network structure. An extremely active inhibitor is formed in situ during vulcanization of SBR and natural rubber using thiuram accelerators. This inhibitor can be used to “reinhibit” acetone-extracted accelerator-cured rubber. When added to sulfur/accelerator, peroxide, or radiation-cured vulcanizates, it improves their age resistance, but only in the case of the sulfur/accelerator cured rubber is this improvement better than with conventional inhibitors. This leads to the conclusion that the efficiency with which an inhibitor protects a vulcanizate varies widely, and conversely it appears that certain types of network structures are more readily protected or that certain inhibitors can function more efficiently in the protection of certain structures than others. In the case of natural rubber cured with TMTD (zinc oxide present), the bulk of the accelerator residue is ZnDMDC, and this residue has been shown to function as a very efficient antioxidant when incorporated into acetone-extracted, accelerator-cured vulcanizate. It is no more effective than conventional inhibitors, however, when incorporated into an acetone-extracted, sulfur/accelerator-cured vulcanizate. Finally, it has been shown that acetone extraction of the various vulcanizates may lead to improvement or worsening of their age resistance, depending upon the nature of the residues resulting from the curing process.

The Electrical Conductivity Stability of Polyaniline Doped with Three Different Acids

2013 ◽  
Vol 774-776 ◽  
pp. 803-806
Author(s):  
Ren Chun Fu ◽  
Jun Du ◽  
Hui Huang ◽  
Zhong Cheng Guo
Keyword(s):  
Electrical Conductivity ◽  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Temperature Dependence ◽  
Methanesulfonic Acid ◽  
Variable Range Hopping ◽  
As Doping ◽  
The Stability ◽  
Better Than

The doping acid will obviously effect on the properties of polyaniline. In order to investigate the industrial acids influence the electrical conductivity stability of polyaniline, the hydrochloric acid (HCl), sulfuric acid (SA) and methanesulfonic acid (MSA) in industrial degree were chosen as doping acids to synthesize polyaniline. The stability of electrical conductivity was measured by in situ temperature. The mechanism of temperature dependence of electrical conductivity was discussed. The results revealed that the stability of polyaniline doped by hydrochloric acid (HCl) was better than that of polyaniline doped by other acids. The variable-range hopping (VRH) model could explain the temperature dependence of electrical conductivity of polyaniline.

Infrared Spectra of Reaction Products of Natural Rubber with Alkylphenol Formaldehyde Resins

1968 ◽  
Vol 41 (3) ◽  
pp. 621-625
Author(s):  
Yu N. Nikitin ◽  
V. G. Epshtein ◽  
M. A. Polyak
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Spectroscopic Studies ◽  
Formaldehyde Resin ◽  
Reaction Products ◽  
Rubber Content ◽  
Chloride Dihydrate ◽  
Unsaturated Rubber ◽  
The Stability ◽  
Recombination Reactions

Abstract Infrared spectroscopic studies were carried out with reaction products of natural rubber with 101K tertiary butylphenol-formaldehyde resin without activators and in the presence of stannous chloride dihydrate and zinc oxide. No reduction was observed in unsaturated rubber content during reaction with resin. Reaction of resin with rubber probably takes place at the α-carbon atom and not at the double bonds. A reduction in the proportion of resin phenol hydroxyl is basically due to its participation in recombination reactions of radicals formed during breakdown of ether bridges of resin. At 150° C activators accelerate decomposition of resin ether bridges, but increase the stability of phenol hydroxyl. In the case of zinc oxide, phenol hydroxyl is sufficiently resistant even at 180° C.

On the stability and in situ epoxidation of natural rubber in latex by performic acid

1991 ◽  
Vol 42 (11) ◽  
pp. 2965-2973 ◽  
Author(s):  
Nguyen Viet Bac ◽  
Levon Terlemezyan ◽  
Marin Mihailov
Keyword(s):  
Natural Rubber ◽  
Performic Acid ◽  
In Situ Epoxidation ◽  
The Stability

Effects of In Situ Formation of Magnesium Aluminate Spinel on Performance of Modified Sizing Nozzle

2013 ◽  
Vol 750-752 ◽  
pp. 1130-1136
Author(s):  
Guang Liang Yuan ◽  
Qun Hu Xue ◽  
Xiang Li ◽  
Yuan Yang
Keyword(s):  
Corrosion Resistance ◽  
Sol Gel ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Sintering Process ◽  
Stabilized Zirconia ◽  
Composite Powders ◽  
The Stability ◽  
Better Than

The modified sizing nozzle with excellent performances was successfully prepared by using of Mg,Y-PSZ as aggregates, Mg,Y,Ca-PSZ as fines, adding a certain amount of Al2O3-ZrO2 composite powders prepared by sol-gel. Effects of magnesium aluminate spinel in-situ synthesized in modified sizing nozzle on its performances were studied in this experiment. The results show that, the content of cubic zirconia in the sizing nozzle was decreased with the increasing of Al2O3-ZrO2 composite powders; the samples of modified sizing nozzle have no diameter-expanded after 30 hours service. The use effects are obviously better than that of Al2O3-ZrO2 composite powders free. The main reason is that a new bond phase magnesium aluminate spinel was in-situ generated through the reaction between Al2O3 in Al2O3-ZrO2 composite powders and the stabilizer MgO from partially stabilized zirconia in the sintering process at high temperature. The spinels embedded in the substrate of zirconia grow further and fill between zirconia particles. This prevents the stabilizer of CaO further desolventizing and also stop losing the eutectics formed by the reaction with compositions of molten steel. Therefore, the stability of zirconia and the corrosion resistance of the sizing nozzle were improved.

A Mirror Furnace for In Situ Residual Stress Measurements by Neutron Diffraction

2014 ◽  
Vol 777 ◽  
pp. 31-34
Author(s):  
Jian Bo Gao ◽  
Dong Feng Chen ◽  
Jun Hong Li ◽  
Yun Tao Liu
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Stress Measurements ◽  
Powder Diffractometer ◽  
Neutron Powder Diffractometer ◽  
The Stability ◽  
Better Than

A mirror furnace for in situ residual stress measurements by neutron diffraction is designed. Bulk and stick sample can be in situ heated up to 1000 degrees centigrade. The stability of the temperature is better than ±1 degree centigrade. This furnace is designed mainly for residual stress neutron diffraction experiments. And also it can be applied to some other neutron instruments such as neutron texture diffractometer, neutron powder diffractometer and triple axis spectrometer.

EFFECT OF IN SITU SURFACE-MODIFIED NANO–ZINC OXIDE ON THE STRUCTURE AND PROPERTIES OF CONVENTIONAL VULCANIZATION IN NATURAL RUBBER

2014 ◽  
Vol 87 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Zhongbiao Man ◽  
Li Deng ◽  
Miao Yang ◽  
Yuehui Chen ◽  
Zhengjie Jin
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
Zinc Oxide ◽  
Natural Rubber ◽  
Nano Zno ◽  
X Ray ◽  
Nano Zinc Oxide ◽  
Nano Zinc ◽  
Surface Modified

ABSTRACT In situ surface-modified nano–zinc oxide (ZnO) had been prepared by the sol-gel method. The microscopic structure of the ZnO particles was characterized by X-ray diffraction and transmission electron microscopy. Scanning electron microscopy with energy-dispersed X-ray spectroscopy was used to observe the dispersal of ZnO in conventional vulcanization of natural rubber (NR). Properties such as cure and tensile characteristics as well as heat-resistance oxygen aging properties were researched and compared. The vulcanized structure of vulcanizate was studied by the balance-swelling method and chemical-detecting process. Results demonstrated that the dispersal of in situ surface-modified nano-ZnO in NR vulcanizate was better than that of ordinary ZnO. Compared with the addition of 5 phr of ordinary ZnO in NR, the tensile strength and elongation of NR vulcanizate filled with 2 phr of in situ surface-modified nano-ZnO increased by 0.55% and 10.34%, respectively. Meanwhile, the retention of tensile strength and elongation of vulcanizate increased by 35.85% and 19.36%, respectively.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

STUDIES ON THE AROMATISATION OF NEUTRAL STEROIDS IN PREGNANT WOMEN

1964 ◽  
Vol 45 (4) ◽  
pp. 535-559 ◽  
Author(s):  
E. Bolté ◽  
S. Mancuso ◽  
G. Eriksson ◽  
N. Wiqvist ◽  
E. Diczfalusy
Keyword(s):  
Pregnant Women ◽  
Comparative Studies ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Radioactive Material ◽  
Placental Barrier ◽  
Therapeutic Abortion ◽  
Limited Ability ◽  
Better Than

ABSTRACT In 15 cases of therapeutic abortion by laparotomy the placenta was disconnected from the foetus and perfused in situ with tracer amounts of radioactive dehydroepiandrosterone (DHA), dehydroepiandrosterone sulphate (DHAS), androst-4-ene-3,17-dione (A), testosterone (T) and 17β-oestradiol (OE2). Analysis of the placentas, perfusates and urine samples revealed an extensive aromatisation of DHA, A and T; more than 70% of the radioactive material recovered was phenolic, and at least 80 % of this phenolic material was identified as oestrone (OE1), 17β-oestradiol (OE2) and oestriol (OE3), the latter being detected only in the urine. Comparative studies indicated that A and T were aromatised somewhat better than DHA and that all three unconjugated steroids were aromatised to a much greater extent than DHAS. Radioactive OE1 and OE2 were isolated and identified in the placentas and perfusates, but no OE3, epimeric oestriols, or ring D ketols could be detected in these sources, not even when human chorionic gonadotrophin (HCG) was added to the blood prior to perfusion. Lack of placental 16-hydroxylation was also apparent when OE2 was perfused. Regardless of the precursor perfused, there was three times more OE2 than OE1 in the placenta and three times more OE1 than OE2 in the perfusate. This was also the case following perfusion with OE2. The results are interpreted as suggesting the existence in the pregnant human of a placental »barrier« limiting the passage of circulating androgen. The barrier consists of a) limited ability to transfer directly DHAS and b) an enzymic mechanism resulting in the rapid and extensive aromatisation of the important androgens DHA, A and T.

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