scholarly journals SPECIALTY NATURAL RUBBER LATEX FOAM: FOAMABILITY STUDY AND FABRICATION PROCESS

2021 ◽  
Author(s):  
Roslim Ramli ◽  
Ai Bao Chai ◽  
Jee Hou Ho ◽  
Shamsul Kamaruddin ◽  
Fatimah Rubaizah Mohd Rasdi ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Cell Structure ◽  
Natural Rubber Latex ◽  
Fabrication Process ◽  
Gelling Agent ◽  
Foam Density ◽  
Foaming Process ◽  
Automotive Parts ◽  
Gelling Time ◽  
Stability Time

ABSTRACT Specialty natural rubber (SpNR) latex, namely, deproteinized natural rubber (DPNR) latex and epoxidized natural rubber (ENR) latex, has been produced to meet specific product's requirements. However, SpNR is normally used in the form of block rubber to manufacture dry rubber products such as tires and automotive parts. The applications of SpNR latex into latex foam products will be diversified. Findings indicate that foamability of SpNR latex is lower compared to normal latex (LATZ) but shows longer stability time after foamed. Findings also indicate that foam collapse and foam coagulate are two main challenges in the fabrication process of SpNR latex foam. Despite these challenges, SpNR latex foam can be fabricated at different density levels. During the foaming process, additional foaming agent is required to fabricate a SpNR latex foam, which is different from fabricating a normal NR latex foam, especially at low latex foam density. Consequently, a higher level of sodium silicofluoride, used as the gelling agent, is required to set the cell structure of the foam. Findings also indicate that foam density influenced the gelling time and volume shrinkage of the SpNR latex foam. An ideal compounding, foaming, and gelling formulation to fabricate SpNR latex foam via Dunlop batch foaming process has been developed. Morphological study showed that all latex foams are open-cell structure, with lower density foam exhibiting higher porosity and mean pore size. Comparison on hysteresis behavior between DPNR and ENR latex foam indicated that ENR latex foam exhibits higher hysteresis loss ratio compared to DPNR latex foam.

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.

A model study on the impact of metal ions on pre-vulcanization of concentrated natural rubber latex and dipped-products

2021 ◽  
pp. 147776062110629
Author(s):  
Porntip Rojruthai ◽  
Narueporn Payungwong ◽  
Jitladda T Sakdapipanich
Keyword(s):  
Natural Rubber ◽  
Metal Ions ◽  
Colloidal Stability ◽  
Mechanical Stability ◽  
Testing Machine ◽  
Natural Rubber Latex ◽  
Tensile Testing Machine ◽  
Model Study ◽  
Stability Time ◽  
The Impact

A model study on the influence of some heavy metal ions on the stability and vulcanization efficiency of uncompounded and compounded high-ammonia natural rubber (HANR) latex was carried out by an exogenous addition and then determined by Brookfield viscometer, mechanical stability time (MST) tester, and tensile testing machine. The case of pre-vulcanized HANR latex with different aging times was determined by the change in the volatile fatty acid (VFA) number, MST, and viscosity. The compounded HANR latex was coagulated by adding Mn2+and Mg2+ while it was unaltered by adding Zn2+, Fe2+, and Cu2+ ions, leading to their colloidal stability. Therefore, these metal ions were chosen further to study the pre-vulcanization of compounded HANR latex. The presence of Zn2+, Fe2+, and Cu2+ in the latex is responsible for the delay in the vulcanization process and changes the appearance of compounded latex. Before compounding, the addition of such metal ions led to the reduction in tensile strength of the obtained gloves. At the same time, there was no effect on the tensile properties of the gloves made from the compounded HANR latex containing the metal ions.

scholarly journals Enhancement of the Antibacterial Activity of Natural Rubber Latex Foam by Blending It with Chitin

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1039 ◽  
Author(s):  
Nanxi Zhang ◽  
Hui Cao
Keyword(s):  
Antibacterial Activity ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Inhibition Zone ◽  
Rubber Latex ◽  
Culture Dish ◽  
Elongation At Break ◽  
E Coli ◽  
Chitin Content ◽  
Foaming Process

To enhance the antibacterial activity of natural rubber latex foam (NRLF), chitin was added during the foaming process in amounts of 1–5 phr (per hundred rubber) to prepare an environmentally friendly antibacterial NRLF composite. In this research, NRLF was synthesized by the Dunlop method. The swelling, density, hardness, tensile strength, elongation at break, compressive strength and antibacterial activity of the NRLFs were characterized. FTIR and microscopy were used to evaluate the chemical composition and microstructure of the NRLFs. The mechanical properties and antibacterial activity of the NRLF composites were tested and compared with those of pure NRLF. The antibacterial activity was observed by the inhibition zone against E. coli. NRLF composite samples were embedded in a medium before solidification. The experimental results of the inhibition zone indicated that with increasing chitin content, the antibacterial activity of the NRLF composites increased. When the chitin content reached 5 phr, the NRLF composite formed a large and clear inhibition zone in the culture dish. Moreover, the NRLF–5 phr chitin composite improved the antibacterial activity to 281.3% of that of pure NRLF against E. coli.

The Effect of Nitrogen Bubbles on Microstructure of Natural Rubber Foams Produced by Bubbling Process

2019 ◽  
Vol 962 ◽  
pp. 91-95
Author(s):  
Kuntida Katkeaw ◽  
Benjaporn Nooklay ◽  
Rungrote Kokoo ◽  
Kalayanee Kooptarnond ◽  
Matthana Khangkhamano
Keyword(s):  
Natural Rubber ◽  
Bubble Column ◽  
Cell Structure ◽  
Natural Rubber Latex ◽  
Constant Flow ◽  
Rubber Latex ◽  
Bubble Volume ◽  
Constant Flow Rate ◽  
Cell Structures ◽  
Nitrogen Bubbles

Natural rubber latex foam (NRF) was produced using nitrogen bubbling process. The process involved flowing of nitrogen with a constant flow rate of 80 cc/min through a bubble column, filled with latex compound, to generate a high bubble-volume inside the column. Microstructure of the finished product was examined using a scanning electron microscope (SEM), in comparison with that of the purchased Dunlop foam. The results showed characteristic of the as-produced foam that they composed of spherical pores with a uniform interconnected-cell structures. On the other hand, the Dunlop foam exhibited non-spherical pores and non-uniform cell structure with broken cells.

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 Influence of fabrication process on the final properties of natural-rubber latex tubes for vascular prosthesis

2006 ◽  
Vol 36 (2b) ◽  
pp. 586-591 ◽  
Author(s):  
W. F. P. Neves-Junior ◽  
M. Ferreira ◽  
M. C. O. Alves ◽  
C. F. O. Graeff ◽  
M. Mulato ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Vascular Prosthesis ◽  
Fabrication Process ◽  
Rubber Latex

Microcellular Foaming of Biodegradable PLA/PPC Composite Using Supercritical CO2

2016 ◽  
Vol 861 ◽  
pp. 247-252
Author(s):  
Zhen Guo Ma ◽  
Xian Hua Lang ◽  
Peng Luo ◽  
Zhen Xiang Xin ◽  
Zhen Xiu Zhang
Keyword(s):  
Cell Structure ◽  
Saturation Pressure ◽  
Saturation Temperature ◽  
Poly Lactic Acid ◽  
Foam Density ◽  
Foaming Process ◽  
Composite Foams ◽  
Controlled Structure ◽  
Poly Propylene ◽  
Foaming Temperature

Poly (lactic acid) (PLA)/poly (propylene carbonate) (PPC) composite foams were microcellular foamed with CO2 through a batch foaming process. The influences of PPC contents, foaming temperature, and saturation pressure on the cell structure and foam density were investigated. The biodegradable PLA/PPC composite foam showed a controlled structure of microcellular and nanocellular. With an increase in saturation temperature and pressure, the cell size was increasing and both the cell density and foam density were decreased simultaneously.

Effect of Storage Conditions on the Properties of Latex. I.

1956 ◽  
Vol 29 (4) ◽  
pp. 1502-1508 ◽  
Author(s):  
H. M. Collier
Keyword(s):  
Natural Rubber ◽  
Acid Content ◽  
Ammonium Acetate ◽  
Mechanical Stability ◽  
Natural Rubber Latex ◽  
Storage Conditions ◽  
Rubber Latex ◽  
Air Space ◽  
Stability Time

Abstract Working with ammonia-preserved natural-rubber latex, concentrated by centrifuging, the author shows that the slight fall in mechanical stability associated with the shipment of bulk supplies of latex can be explained by the fact that, during shipment, latex does not have access to the oxygen of the air. The mechanical stability of samples taken at the time of shipment increased in value when there was an appreciable air-space in the storage bottle, but fell when the bottle was full and air was excluded. These differences were accentuated when air was replaced by oxygen and was then possible to find marked differences not only in mechanical stability time but also in the volatile fat acid content of the latexes. The increase of volatile fat acid content of the samples stored in the absence of air was much greater than in the sample stored in the presence of oxygen. The fall of mechanical stability in the absence of air is ascribed to the formation of increasing quantities of salts, such as ammonium acetate. In the presence of oxygen, the rate of formation of salts of this type is very much less, and at the same time other changes take place which lead to a marked increase of mechanical stability.

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.

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