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

scholarly journals Studies of the In-Situ Epoxidation of Rubber (Hevea Brasiliensis)Seed Oil by Performic Acid

2019 ◽  
Vol 1378 ◽  
pp. 022025
Author(s):  
O.R. Obanla ◽  
J.D. Udonne ◽  
O.O. Ajani ◽  
M.E. Ojewumi ◽  
O.J. Omodara ◽  
...  
Keyword(s):  
Hevea Brasiliensis ◽  
Seed Oil ◽  
Performic Acid ◽  
In Situ Epoxidation

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.

Mechanical properties, thermal behaviors and oil resistance of epoxidized natural rubber/multiwalled carbon nanotube nanocomposites prepared via in situ epoxidation

2016 ◽  
Vol 49 (2) ◽  
pp. 99-119 ◽  
Author(s):  
Saowaroj Chuayjuljit ◽  
Piyaphorn Mungmeechai ◽  
Anyaporn Boonmahitthisud
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Carbon Nanotube ◽  
Natural Rubber ◽  
Multiwalled Carbon Nanotube ◽  
Epoxidized Natural Rubber ◽  
Multiwalled Carbon ◽  
Oil Resistance ◽  
In Situ Epoxidation

Epoxidized natural rubber (ENR)/multiwalled carbon nanotube (MWCNT) nanocomposites were prepared via in situ epoxidation of natural rubber (NR) using a molar ratio of formic acid/hydrogen peroxide to isoprene unit at 0.75/0.75 with five loadings of MWCNTs, ranging from 0.5–2.5 parts per hundred parts of rubber (phr), at 50°C for 4 h. Based on Fourier transform infrared spectra, the epoxide content of ENR in the nanocomposites was about 32.5–33.2 mole%. Accordingly, the products were referred to ENR30/MWCNT nanocomposites. The curing characteristics, mechanical properties (tensile properties, tear strength, and hardness), glass transition temperature ( Tg), thermal stability, and oil resistance of these in situ ENR30/MWCNT nanocomposites were investigated and compared with NR and neat ENR30. The results showed that the scorch and cure times of ENR30/MWCNT nanocomposites were the longest followed by NR and ENR30. The incorporation of an appropriate amount of MWCNTs into the in situ epoxidation apparently improved the properties of NR. Among them, the nanocomposites filled with 2 phr MWCNTs exhibited the highest mechanical properties, Tg, thermal stability, and oil resistance. The mechanical properties of the in situ nanocomposites were also compared with those of the control nanocomposites prepared by adding MWCNTs directly in the prepared ENR30 latex. It was found that at similar MWCNT loadings, the in situ nanocomposites exhibited higher mechanical properties than the control nanocomposites.

Preparation and Properties of Poly(Lactic Acid)/Epoxidized Natural Rubber/Nano-Silica Composites

2018 ◽  
Vol 773 ◽  
pp. 20-24
Author(s):  
Auttapol Mongkolvai ◽  
Saowaroj Chuayjuljit ◽  
Phasawat Chaiwutthinan ◽  
Amnouy Larpkasemsuk ◽  
Anyaporn Boonmahitthisud
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Impact Strength ◽  
Natural Rubber ◽  
Silica Nanoparticle ◽  
Performic Acid ◽  
Epoxidized Natural Rubber ◽  
Poly Lactic Acid ◽  
Nano Silica ◽  
In Situ Epoxidation

This study aimed to improve the toughness property of poly(lactic acid) (PLA) by incorporating epoxidized natural rubber (ENR), an elastomeric material and silica nanoparticle (nSiO2), a spherical inorganic nanofiller. ENR with 30mol% epoxidation (ENR 30) was first prepared via in situ epoxidation of natural rubber by performic acid generated from the reaction between formic acid and hydrogen peroxide in the latex stage. The PLA was melt blended with three weight percentages (10, 20 and 30wt%) of ENR in an internal mixer, followed by a compression molding. The effects of ENR loadings on the mechanical properties and thermal stability of the blends were first investigated. It was found that the addition of ENR 30 increased the toughness property of the blends. The blend at 20wt% ENR 30 exhibited the highest impact strength and elongation at break, and so was selected for preparing nanocomposites with three loadings (1, 2 and 3 parts per hundred of resins) of nano-silica (nSiO2). The results showed that all PLA/ENR 30/nSiO2 nanocomposites exhibited higher impact strength and thermal stability than the neat 80/20 PLA/ENR 30 blend.

In situ epoxidation of ethylene propylene diene rubber by performic acid

Polymer ◽  
1997 ◽  
Vol 38 (21) ◽  
pp. 5407-5410 ◽  
Author(s):  
Xuehui Wang ◽  
Huixuan Zhang ◽  
Zhigang Wang ◽  
Bingzheng Jiang
Keyword(s):  
Performic Acid ◽  
Ethylene Propylene ◽  
In Situ Epoxidation ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber

scholarly journals Use of TBzTD as Noncarcinogenic Accelerator for ENR/SiO2 Nanocomposites: Cured Characteristics, Mechanical Properties, Thermal Behaviors, and Oil Resistance

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Laksamon Raksaksri ◽  
Saowaroj Chuayjuljit ◽  
Phasawat Chaiwutthinan ◽  
Anyaporn Boonmahitthisud
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Dynamic Mechanical Properties ◽  
Performic Acid ◽  
Thermal Behaviors ◽  
Oil Resistance ◽  
Curing Characteristics ◽  
Before And After ◽  
In Situ Epoxidation ◽  
Sio2 Nanocomposites

This study reported the use of tetrabenzylthiuram disulphide (TBzTD) as a noncarcinogenic accelerator in a traditional sulfur curing system of epoxidized natural rubber (ENR)/nanosilica (nSiO2) composites. ENR used in this work was synthesized via in situ epoxidation of natural rubber (NR) in the presence of performic acid generated from the reaction of formic acid and hydrogen peroxide at 50°C for 8 h to acquire the epoxide content of about 40 mol%. Accordingly, the resulting ENR was referred to as ENR 40. The curing characteristics, mechanical properties, thermal behaviors, dynamic mechanical properties, and oil resistance of ENR 40/nSiO2 nanocomposites filled with three loadings of nSiO2 (1, 2, and 3 parts per hundred parts of rubber) were investigated and compared with NR and neat ENR 40. The results revealed that the scorch and cure times of ENR 40/nSiO2 nanocomposites were slightly longer than those of NR but slightly shorter than those of ENR 40. The tensile properties and tear strength for both before and after aging of all ENR 40/nSiO2 nanocomposites were higher than those of ENR 40, while the glass transition temperature, storage modulus at −65°C, thermal stability, and oil resistance of ENR 40/nSiO2 nanocomposites were higher than those of NR and ENR 40.

PREPARATION AND CHARACTERIZATION OF SPECIALTY NATURAL RUBBER LATEX CONCENTRATE

2021 ◽  
Author(s):  
Roslim Ramli ◽  
Chai Ai Bao ◽  
Ho Jee Hou ◽  
Shamsul Kamaruddin ◽  
Fatimah Rubaizah Mohd Rasdi ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Membrane Separation ◽  
Natural Rubber Latex ◽  
Elastic Solid ◽  
Total Solid ◽  
Solid Content ◽  
Total Solid Content ◽  
Hydrolysis Process ◽  
In Situ Epoxidation

ABSTRACT Conventionally, specialty natural rubber (SpNR) latex, namely, deproteinized natural rubber (DPNR) latex and epoxidized natural rubber (ENR) latex, are prepared from low ammonia latex (LATZ) causing high material cost. To address this issue, the objective of this study is to prepare SpNR latex directly from freshly tapped NR latex. In this work, DPNR latex is prepared via a heat enzymatic hydrolysis process, while ENR latex is prepared via in situ epoxidation chemical modification process. In addition, both DPNR and ENR latex were concentrated to 60% total solid content via ultrafiltration process using membrane separation technology. Physiochemical properties of DPNR, ENR, and LATZ latex were compared. Results show that the total solid content, dry rubber content, and alkalinity level of the latexes achieved the targeted value. This study also found that nitrogen content of DPNR latex, LATZ latex, and ENR latex were at 0.11%, 0.29%, and 0.25%, respectively, indicating successful deproteinization of the DPNR latex. On the other hand, the epoxidation level of ENR latex produced in this study was at 46.3%, which is slightly lower than the targeted level of 50%. Rheological studies found that ENR latex exhibits the highest viscosity, followed by DPNR and LATZ, but all show characteristic shear-thinning behavior. This study also found that LATZ and DPNR latex are more liquid-like in nature, while ENR latex behaves more like an elastic solid. Non-ionic surfactants play a major role in influencing flow and deformation behavior of the ENR and DPNR latex.

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.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

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