scholarly journals Effect of Stabilizer States (Solid Vs Liquid) on Properties of Stabilized Natural Rubbers

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 741 ◽  
Author(s):  
Khwanchat Promhuad ◽  
Wirasak Smitthipong
Keyword(s):  
Natural Rubber ◽  
Liquid State ◽  
Room Temperature ◽  
Gel Formation ◽  
Rubber Industry ◽  
Gel Content ◽  
Mooney Viscosity ◽  
Mixing States ◽  
Hydroxylamine Sulfate ◽  
Stabilizer States

The main objective of this work is to study the effect of hydroxylamine sulfate or stabilizer states (solid vs liquid) on the storage hardening of natural rubber (NR). Several types of natural rubber samples were prepared: unstabilized NR samples and stabilized NR samples: (i) dry NR with 0.2 and 2.0 parts per hundred rubber (phr) of dry hydroxylamine sulfate, and (ii) natural latex with 0.2 and 2.0 phr of liquid hydroxylamine sulfate. The samples were characterized immediately (time 0) and after 12 weeks of storage at room temperature, respectively. We found that the Mooney viscosity, gel content, and Wallace plasticity of NR without a stabilizer increases with storage hardening for 12 weeks. However, two types of stabilized NR samples represent constant values of those three parameters, because hydroxylamine sulfate inhibits network and gel formation in NR. Interestingly, the mixing states (solid vs liquid) between natural rubber and the stabilizer affect the properties of stabilized NR. This could be explained by the better dispersion and homogeneous nature of liquid stabilizers in natural latex (liquid state), and thus the higher loading of the stabilizer in the liquid state. This is important, as the stabilization of NR properties as a function of time is required by rubber industry. This study is a utilization model from theory to application.

Gel Formation in Natural Rubber Latex: 2. Effect of Magnesium Ion

2003 ◽  
Vol 76 (5) ◽  
pp. 1185-1193 ◽  
Author(s):  
L. Tarachiwin ◽  
J. T. Sakdapipanich ◽  
Y. Tanaka
Keyword(s):  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Storage Period ◽  
Gel Formation ◽  
Gel Content ◽  
Gel Fraction ◽  
Rate Of Increase ◽  
2So4 Concentration ◽  
Gel Phase ◽  
Long Storage

Abstract The effect of Mg2+ ions on the gel formation in fresh and commercial high ammonia natural rubber latices (FL-latex and commercial HA-latex) was analyzed from the gel content and 2+ content after treatment with (NH4)2SO4. The gel content of rubber from commercial HA-latex decreased significantly after (NH4)2SO4 treatment comparable to that of FL-latex. Long-storage commercial HA-latex containing 50% gel fraction showed no decrease in 2+ content after (NH4)2SO4 treatment. This gel fraction was not solubilized in toluene by the treatment of a proteolytic enzyme in latex or ethanol/toluene mixed solvent extraction of rubber. The 2+ content of rubber in long-storage commercial HA-latex, 0.005% (w/w rubber), decreased after treatment with (NH4)2SO4, while the same treatment showed little change on FL-latex, 0.035%. The toluene soluble fraction of these latices showed a decrease in the Mn value with an increase in the (NH4)2SO4 concentration. The gel content of FL- and HA-lattices increased with an increasing storage period in the presence and absence of (NH4)2SO4. The initial rate of increase in the gel content was slow in the case of FL-latex. These findings indicate that the gel fraction in HA-latex is partly formed by ionic crosslinks caused by 2+ ions. Whereas, the gel phase in long-storage commercial HA-latex is presumed to be a hard gel predominantly formed by covalent bonding.

Role of Gel Content on the Structural Changes of Masticated Natural Rubber

2013 ◽  
Vol 844 ◽  
pp. 101-104 ◽  
Author(s):  
Adun Nimpaiboon ◽  
Sureerut Amnuaypornsri ◽  
Jitladda Sakdapipanich
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Shear Force ◽  
Structural Changes ◽  
Gel Content ◽  
Gel Fraction ◽  
Accelerated Storage ◽  
Strain Sweep ◽  
Mooney Viscosity

In this study, natural rubber (NR) containing various amounts of gel was prepared by accelerated storage hardening to investigate the role of gel content on the structural changes of masticated NR. The NR samples containing various amounts of gel were subjected to mastication at various times, and subsequently characterized for the change of gel content, molecular weight, and Mooney viscosity to evaluate the role of gel content on these parameters. Furthermore, an oscillatory shear experiment using a strain sweep test was applied in this study to elucidate the structural changes of rubber samples after mastication. The results revealed that the Mooney viscosity was related to the percentage of gel fraction that has been proven to be the result of the interactions of proteins and phospholipids at the chain ends. The gel fraction of NR can be decomposed into a sol fraction by shear force during mastication and the mastication time for decomposition of gel relates to the initial gel content of the rubber. After mastication for 15 min, although the gel fraction of NR can be decomposed to ~0% w/w, the interactions of proteins and phospholipids at the chain ends still existed, and their quantities is corresponded to the gel content of raw rubber.

Color and Antioxidant Changes in Various Natural Rubber Processes

2015 ◽  
Vol 754-755 ◽  
pp. 230-234 ◽  
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).

scholarly journals Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

2010 ◽  
Vol 6 ◽  
pp. 25008
Author(s):  
R. Caborgan ◽  
J.M. Muracciole ◽  
B. Wattrisse ◽  
A. Chrysochoos
Keyword(s):  
Natural Rubber ◽  
Room Temperature ◽  
Thermomechanical Analysis

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

1964 ◽  
Vol 37 (4) ◽  
pp. 866-877 ◽  
Author(s):  
M. Lowman ◽  
H. E. Keller
Keyword(s):  
Natural Rubber ◽  
Room Temperature ◽  
Dynamic Testing ◽  
Effect Of Temperature ◽  
Ethylene Propylene ◽  
Rate Decrease ◽  
Resonant Beam

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.

scholarly journals Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives

2017 ◽  
Vol 19 (47) ◽  
pp. 31823-31829 ◽  
Author(s):  
Guoquan Liu ◽  
Shu-Hao Liou ◽  
Nikolay Enkin ◽  
Igor Tkach ◽  
Marina Bennati
Keyword(s):  
Laser Irradiation ◽  
Spin Polarization ◽  
Dynamic Nuclear Polarization ◽  
Liquid State ◽  
Room Temperature ◽  
Nuclear Polarization ◽  
Continuous Wave ◽  
Continuous Wave Laser ◽  
Wave Laser ◽  
Nmr Signal Enhancement

Continuous wave laser irradiation of fullerene–nitroxide derivatives at room temperature leads to spin polarization and NMR signal enhancement of toluene solvent protons.

Gel Formation in Natural Rubber Latex: 1. Effect of (NH4)2HPO4 and TMTD/ZnO Additives

2003 ◽  
Vol 76 (5) ◽  
pp. 1177-1184 ◽  
Author(s):  
L. Tarachiwin ◽  
J. T. Sakdapipanich ◽  
Y. Tanaka
Keyword(s):  
Natural Rubber Latex ◽  
Gel Formation ◽  
Rubber Latex ◽  
Tetramethylthiuram Disulfide ◽  
Gel Content ◽  
Gel Fraction ◽  
Initial Stage ◽  
High Ammonia ◽  
Long Time ◽  
Long Storage

Abstract The rubber from commercially obtained high-ammonia latex (commercial HA-latex) increased in gel content significantly after long preservation of the latex with 1.0% w/v tetramethylthiuram disulfide (TMTD) and zinc oxide (ZnO). Deproteinization of the HA-latex did not decrease the gel content. The gel fraction of deproteinized commercial HA-latex (DPHA-latex) was not solubilized by toluene containing 1.0% ethanol, showing that the gel fraction is composed of chemically crosslinked rubber. The addition of (NH4)2HPO4, which is usually added to fresh latex (FL-latex) to remove excess amounts of Mg2+ ions by centrifugation, decreased the gel formation in FL-latex preserved with 0.6 % v/v NH4OH due to the removal of Mg2+ ions. The excess amounts of (NH4)2HPO4 accelerated the gel formation in preserved FL-latex and commercial HA-latex. The addition of 0.1% w/v TMTD/ZnO to preserved FL-latex treated with 5% w/v (NH4)2HPO4 caused an increase of gel content during storage. The gel formation in the commercial HA-latex during long time storage was presumed to be caused by excess amounts of Mg2+ ions, TMTD/ZnO and (NH4)2HPO4. Here, TMTD/ZnO accelerated the gel formation at the initial stage of storage, while (NH4)2HPO4 affected in long storage.

Preparation and Characterization of Epoxidized-30% Poly(methyl methacrylate)-grafted Natural Rubber Polymer Electrolyte

2014 ◽  
Vol 28 ◽  
pp. 163-170 ◽  
Author(s):  
Khuzaimah Nazir ◽  
Siti Fadzilah Ayub ◽  
Ahmad Fairoz Aziz ◽  
Ab Malik Marwan Ali ◽  
Muhd Zu Azhan Yahya
Keyword(s):  
Ionic Conductivity ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Room Temperature ◽  
Ionic Conduction ◽  
Lithium Triflate ◽  
Poly Methyl Methacrylate ◽  
Order Of Magnitude ◽  
Cast Technique

In this study, a freestanding thin film composed of lithium triflate (LiTf) salt (30-40 wt.%) and epoxidized-30% poly (methyl methacrylate)-grafted natural rubber (EMG30) (50, 54.6, 62.3 mol %) were prepared by a solvent cast technique. The EMG30 were found to increase the ionic conductivity of EMG30-LiTf by one order of magnitude compared to MG30-LiTf. The highest ionic conductivity achieved was 5.584 x10-3Scm-1at room temperature when 40 wt.% of LiTf salts were introduced into 62.3 mol % EMG30. The ionic conduction mechanisms in EMG30-LiTf electrolytes obey Arrhenius rule in which the ion transport in these materials is thermally assisted.

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