scholarly journals Preparation of natural rubber-OMMT nanocomposites using mechanical mixing and acid free co-coagulation methods: effect of processing method on mechanical properties

2020 ◽  
Vol 10 (3) ◽  
pp. 5640-5647
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Sodium Dodecyl ◽  
Natural Rubber Latex ◽  
Gelling Agent ◽  
Ammonium Bromide ◽  
Mechanical Mixing ◽  
Ordered Structures ◽  
Bound Rubber ◽  
Cure Time

The masterbatches were prepared by acid free co-coagulation (AFCC) method in which OMMT was incorporated into natural rubber latex (NRL) or conventional mechanical mixing. Inherent slow coagulation, and drying, stages of the AFCC method were overcome by introducing a novel gelling agent; a combination of two surfactants, namely, Cetyl tri methyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS). Six nanocomposites (A-nanocomposite, C-nanocomposite and M-nanocomposite) were prepared at the OMMT loadings of 2 and 5 phr; of them, two with gelling agent (A-2, A-5) and two without gelling agent (C-2, C-5) using AFCC method and two using mechanical mixing (M-2 & M-5). Controls of them (A-0, C-0 and M-0) were prepared without using OMMT. X-ray diffractograms and scanning electron spectroscopic images showed that a higher amount of aggregated clay structures was present in the M-nanocomposites, and less aggregated clay structures were present in C-nanocomposites. However randomly distributed ordered structures along with exfoliated clay structures were in the A-nanocomposites. Crosslink density and the bound rubber content of the A-nanocomposites were significantly higher than M-nanocomposites but lower than C-nanocomposites. The mechanical properties of the A- nanocomposites and C-nanocomposites were greater than those of the M-nanocomposites at each OMMT loading. The cure time of the A-nanocomposites and C-nanocomposites were also remarkably lowered compared to the M-nanocomposites. It was observed that the effect of the combined gelling agent had no adverse effect on mechanical properties.

scholarly journals Enhancement of mechanical properties of natural rubber–clay nanocomposites through incorporation of silanated organoclay into natural rubber latex

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 144-153 ◽  
Author(s):  
Sudarshana Jayaraj Perera ◽  
Shantha Maduwage Egodage ◽  
Shantha Walpalage
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Sodium Dodecyl ◽  
Natural Rubber Latex ◽  
Gelling Agent ◽  
Rubber Matrix ◽  
Ammonium Bromide ◽  
Clay Nanocomposites ◽  
Cetyl Trimethyl Ammonium ◽  
Clay Layers

AbstractIn this study, cetyl trimethyl ammonium bromide (CTAB) modified montmorillonite (MMT) which is called as organoclay (OMMT) was mixed with natural rubber, and masterbatches were produced using the acid-free co-coagulation (AFCC) method in the presence of a combined gelling agent, a mixture of CTAB and sodium dodecyl sulfate. The OMMT was further modified by grafting of bis(triethoxysilylpropyl)tetrasulfide as to reduce the surface energy in silanated organoclay (OMMT-S). As expected, the nanocomposites prepared with OMMT-S compared to those with OMMT exhibited greater mechanical properties due to the development of rubber–clay interactions and due to proper dispersion of small clay layers in the rubber matrix combined with the gelling agent. The improvement of elongation at break, hardness and tear strength of the nanocomposites with OMMT/OMMT-S was an added advantage when the nanocomposites are prepared using the AFCC method without having any adverse effect from the combined gelling agent.

Surfactant Treatment and Leaching Combination Process for Preparation of Deproteinized Natural Rubber Latex

2015 ◽  
Vol 659 ◽  
pp. 500-504
Author(s):  
Jirapornchai Suksaeree ◽  
Wirach Taweepreda ◽  
Wiwat Pichayakorn
Keyword(s):  
Natural Rubber ◽  
Skin Irritation ◽  
Sodium Dodecyl ◽  
Natural Rubber Latex ◽  
Rubber Latex ◽  
Combination Process ◽  
Surfactant Treatment ◽  
Leaching Process ◽  
Sodium Lauryl Ether Sulfate ◽  
Cocamidopropyl Betaine

This study aimed to improve the efficacy of protein removal from fresh natural rubber latex (NRL) and to decrease the production cost by using surfactant treatment and leaching combination processes. The 0.5-3% anionic surfactants, i.e. sodium dodecyl sulfate or sodium lauryl ether sulfate, nonionic tween80 surfactant, or an amphoteric cocamidopropyl betaine surfactant was used in surfactant treatment process. Moreover, water, aqueous surfactant solutions, and/or 1-5% organic solvents (i.e. ethanol, isopropanol and/or acetone) was then used in leaching process. The fresh NRL was preserved by paraben compounds in the presence of surfactant at ambient temperature for 20-120 minutes, and then centrifuged. This might prevent the skin irritation of deproteinized NRL (DNRL) caused by ammonium stabilizer that normally uses in latex industry. The upper rubber mass was then leached for upto three cycles with leaching solvents, and then finally redispersed in distilled water. The milky-like DNRLs were obtained by these processes. Their dry rubber contents were 41-47% that could be adjusted. Their viscosities were 9-13 centipoises with the pH of 6.04-6.61. The protein residues in these DNRLs were 0.0000-0.3244% which were lower than that of fresh NRL (1.2428%). These indicated the efficacy of studied deproteinization process for 73.90-100.0%. Types and concentrations of surfactant, incubation times, leaching solvents, and cycles of leaching process affected the efficacy of deproteinization process. Moreover, the properties of these dried films were not different from that of fresh NR film. This DNRL could be further used for several applications including medical skin products.

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.

Effect of Bio-Fibrils Incorporating with TiO2 on the Properties of Natural Rubber Foam

2016 ◽  
Vol 718 ◽  
pp. 26-29
Author(s):  
Kanokwan Seerod ◽  
Jantaravan Sangjumpa ◽  
Varinrumpai Seithtanabutara
Keyword(s):  
Natural Rubber ◽  
Smooth Surface ◽  
Testing Machine ◽  
Natural Rubber Latex ◽  
Gelling Agent ◽  
Acid Mixture ◽  
Rubber Latex ◽  
Composite Foam ◽  
Physical Strength ◽  
Universal Testing

In this study, empty fruit bunch (EFB) was pretreated and bleached with 2.5 M NaOH at 80°C for 8 h and ClNaO for 12 h, respectively. Then it was hydrolyzed in the acid mixture of 5%wt. C2H2O4 and 48%wt. H2SO4 for 24 h. The obtained bio-fibrils and titanium dioxide (TiO2) were filled into the natural rubber latex (NRL) with the help of vulcanizing agent, antioxidant, accelerators, curing agent and gelling agent to get the resulted natural rubber (NR) foams. The morphology properties and physical properties of all foam samples were checked by using scanning electron microscope and universal testing machine, respectively. The properties of EFB fibers and bio-fibrils were also compared. The density of prepared foams was found out. Resulted showed that the bio-fibrils have the smooth surface with smaller size than BFB fibers. Addition of these bio-fibrils and TiO2 particles into NRL latex contributed the significant improvement of density and physical strength of the resulted foams. The composite foam containing 1.0 phr of bio-fibrils and 2.5 phr of TiO2 had the highest value of density and tensile stress.

PROTEIN INFLUENCE ON THE MECHANICAL PROPERTIES OF NR

2021 ◽  
Author(s):  
Yayoi Akahori ◽  
Misao Hiza ◽  
Soki Yamaguchi ◽  
Seiichi Kawahara
Keyword(s):  
Mechanical Properties ◽  
Nmr Spectroscopy ◽  
Sodium Dodecyl Sulfate ◽  
Carbon Black ◽  
Natural Rubber ◽  
Hevea Brasiliensis ◽  
Sodium Dodecyl ◽  
Swelling Degree ◽  
Deproteinized Natural Rubber ◽  
Rubber State

ABSTRACT Protein effect on vulcanization of NR, obtained from Hevea brasiliensis, was investigated by analyzing the crosslinking structure of the resulting vulcanizates prepared from untreated NR, deproteinized natural rubber (DPNR), and protein-free natural rubber (PFNR) by swelling methods and rubber-state NMR spectroscopy. The proteins present in NR were removed by three methods: deproteinization with enzyme, urea, or urea–acetone in the presence of sodium dodecyl sulfate. The amount of proteins present in NR, approximately 0.238 w/w%, was reduced to 0.000 w/w% by urea–acetone deproteinization, whereas it was reduced to approximately 0.003 and 0.019 w/w% by enzyme and urea deproteinizations, respectively. Hardness, swelling degree, and crosslinking structure depended on the amount of proteins. Changes in mechanical properties for the vulcanizates prepared from not only non-filler compounds but also carbon black–filled and silica-filled compounds were attributed to the amount of proteins.

Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

2005 ◽  
Vol 21 (3) ◽  
pp. 183-199
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Three Dimensional ◽  
Elongation At Break ◽  
Tear Strength ◽  
Vulcanized Rubber ◽  
Dimensional Network ◽  
Polymeric Chains ◽  
Cure Time

De-vulcanization of vulcanized elastomers represents a great challenge because of their three-dimensional network structure. Sulfur-cured gum natural rubbers containing three different sulfur/accelerator ratios were de-vulcanized by thio-acids. The process was carried out at 90 °C for 10 minutes in an open two-roll cracker-cum-mixing mill. Two concentrations of de-vulcanizing agent were tried in order to study the cleavage of the sulfidic bonds. The mechanical properties of the re-vulcanized rubber (like tensile strength, modulus, tear strength and elongation at break) were improved with increasing concentrations of de-vulcanizing agent, because the crosslink density increased. A decrease in scorch time and in optimum cure time and an increase in the state of cure were observed when vulcanized rubber was treated with high amounts of de-vulcanizing agent. The temperature of onset of degradation was also increased with increasing concentration of thio-acid. DMA analysis revealed that the storage modulus increased on re-vulcanization. From IR spectroscopy it was observed that oxidation of the main polymeric chains did not occur at the time of high temperature milling. Over 80% retention of the original mechanical properties (like tensile strength, modulus, tear strength and elongation at break) of the vulcanized natural rubber was achieved by this mechanochemical process.

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