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.

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.

Alternative Methods for Accelerating Mechanical Stability of Concentrated Natural Rubber Latex

2018 ◽  
Vol 382 ◽  
pp. 26-30 ◽  
Author(s):  
Dechnarong Pimalai ◽  
Yodsathorn Wongngam ◽  
Cattaleeya Pattamaprom
Keyword(s):  
Natural Rubber ◽  
Colloidal Stability ◽  
Mechanical Stability ◽  
Natural Rubber Latex ◽  
Negative Ions ◽  
Alternative Methods ◽  
Rubber Latex ◽  
Forming Process ◽  
Slow Increase ◽  
Phospholipid Hydrolysis

The mechanical stability time (MST) of latex is an important parameter indicating the colloidal stability of concentrated natural rubber latex (CNRL). This stability is crucial for the transport and storage of CNRL before the product forming processes. A popular method to increase the MST of CNRL in Thailand is by adding laureth soap or other surfactants. Nevertheless, the laureth soap provides a steady but slow increase in the MST without reaching a stable value after 30 days. At the same time, the phospholipids on the surfaces of natural rubber latex particles will naturally undergo hydrolysis reaction leading to even higher MST. For long storage, too high MST leads to coagulation problem in the product-forming step. Therefore, alternative methods were studied in this research to expedite phospholipid hydrolysis, which results in the increase in MST for CNRL without causing problems from excessive negative ions in the product-forming process. The alternative methods including heating in the presence of metal chips and the use of enzyme lipase were compared to the popular laurate soap addition method. It was found that lipase addition was the most effective method to expedite the hydrolysis of phospholipids to reach the standard MST value within 3 days, and reach a plateau within 10 days.

Thermal Insulation Performances of Plaster Composites Based on Embedding Natural Rubber Latex Compound

2021 ◽  
Vol 904 ◽  
pp. 441-446
Author(s):  
Nuchnapa Tangboriboon ◽  
Sarun Muntongkaw ◽  
Sompratthana Pianklang
Keyword(s):  
Natural Rubber ◽  
Thermal Insulation ◽  
Water Solubility ◽  
Testing Machine ◽  
Natural Rubber Latex ◽  
Cold Weather ◽  
Mechanical And Thermal Properties ◽  
Rubber Latex ◽  
Universal Testing ◽  
Cost Of Energy

Adding 0, 20, and 50 wt% natural-rubber latex compound into the plaster ceiling matrix affected to increase the physical-mechanical-thermal performance properties of plaster ceiling composites. Adding 50 wt% natural rubber latex compound into plaster composites can increase the superior adhesion of the nail-tensile resistance equal to 57.54 N and decrease thermal conductivity equal to 0.0634 W/m.K. In addition, adding natural rubber latex compounds into plaster composites can reduce water solubility, brittleness, impact, and cost of energy consumption due to the exterior temperature. Adequate thermal insulation for roofing, ceiling, and wall systems also reduces radiative losses that chill occupants in cold weather, and reduce interior surface temperatures in the summer, thereby optimizing the comfort of building occupants. The mechanical and thermal properties of plaster composites were investigated by using a Universal Testing Machine (UTM) and heat flow meter, respectively, measured according to TIS 1211-50, TIS 219-2522, and ASTM C518.

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.

Natural rubber latex allergy: the impact on lifestyle and quality of life

2004 ◽  
Vol 51 (5-6) ◽  
pp. 317-318 ◽  
Author(s):  
V. J. Lewis ◽  
M. M. U. Chowdhury ◽  
B. N. Statham
Keyword(s):  
Quality Of Life ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Latex Allergy ◽  
Rubber Latex ◽  
The Impact

Mechanical Stability Test for Hevea Latex

1950 ◽  
Vol 23 (4) ◽  
pp. 981-994
Author(s):  
H. G. Dawson
Keyword(s):  
High Speed ◽  
Colloidal Stability ◽  
Mechanical Stability ◽  
Stability Test ◽  
Simple Method ◽  
Latex Particles ◽  
Interfacial Film ◽  
Total Solids ◽  
Stability Time

Abstract The mechanical stability test is a rapid, simple method of estimating the colloidal stability or quality of Hevea latex by high-speed stirring. Latex particles start to agglomerate as soon as the peripheral speed of the agitator reaches a certain minimum value. Progressive flocculation continues until mechanical coagulation occurs. The end point is defined as the time in seconds required to coagulate 0.5 to 1.0 per cent of the total solids. If the shear is constant, the time is proportional to the colloidal stability, which depends upon the interfacial film between the latex particles and the serum. The mechanical stability time depends critically on the size, the total solids, and the temperature of sample.

Effect of silver nanoparticle (AgNp) mixed with calcium carbonate on impact, hardness and tensile strength properties of aluminium 6063

2020 ◽  
pp. 002199832092314
Author(s):  
Adefemi Adeodu ◽  
Lateef Mudashiru ◽  
Ilesanmi Daniyan ◽  
Abdulmalik Awodoyin
Keyword(s):  
Tensile Strength ◽  
Calcium Carbonate ◽  
Aluminium Alloy ◽  
Testing Machine ◽  
Charpy Impact ◽  
Stir Casting ◽  
Optical Microscope ◽  
Tensile Testing Machine ◽  
Casting Technique ◽  
The Impact

Mechanical properties (impact, hardness and tensile strength) characterization of samples containing homogenous mixtures of Al 6063 matrix and varying amount of silver nanoparticles mixed with calcium carbonate at 2, 4, 6% weight fractions, respectively, produced by method of stir casting were carried out. Measurement of impact energy, hardness and tensile strength of the produced samples at 24℃ (ambient) temperature was done by Charpy impact, Brinell hardness and universal tensile testing machine in accordance to ASTM E23, E384 and E8/E8M-13M, respectively. The magnitude of impact and hardness increased evidently with increase in percentage weight fraction of the AgNPs. The refined samples were examined under an optical microscope. The fracture surfaces of the impact test samples were further examined by scanning electron microscopy. There is an increase in tensile strength, elongation and modulus of elasticity of Al-AgNP composites compared to as-cast aluminium alloy. The use of stir-casting technique influences the homogeneity and microstructure of the composites positively. It is concluded that Al-silver nanocomposites possess better qualities in hardness and strength and can replace conventional aluminium alloy in terms of performance and longer life in industrial application.

Thermal Insulator Made from Solid Natural Rubber: Part 1 - Formulation of Rubber Compounding, Appropriate Forming Condition and Basic Properties

2017 ◽  
Vol 737 ◽  
pp. 567-571
Author(s):  
Teeratat Sopakitiboon ◽  
Apaipan Rattanapan ◽  
Surakit Tuampoemsab
Keyword(s):  
Natural Rubber ◽  
Testing Machine ◽  
Optical Microscope ◽  
Hot Press ◽  
Tensile Testing Machine ◽  
Thermal Insulator ◽  
Closed Cell ◽  
Roll Mill ◽  
Average Maximum ◽  
Rubber Part

Closed cell rubber sponge applied as thermal insulator made from solid natural rubber (NR) was prepared by using Supercell DPT as a blowing agent. Rubber chemicals and STR 20, solid NR, were mixed on a two roll mill prior to prepare the specimen by hot press machine. Curing behaviors of the compounded solid NR with various types of sulfur and peroxide vulcanizations were characterized with moving die rheometer (MDR) at 150 and 170°C. Tensile and compressive strengths of the rubber insulator were measured by universal tensile testing machine followed by ASTM D412 and ASTM D395, respectively. Bubble size of the blown up rubber was inspected by an average maximum length of the bubble by using optical microscope. It should be notice from the experimental that all rubber formula both of sulfur and peroxide systems showed loading percentages to completely expand in a mold by about 38 to 48. Rubber insulator blown up with Supercell DPT used by semi-efficient vulcanization (semi-E.V.) unconcealed predominant results among all curing systems so that further investigations of the formulation as heat stuff will be discussed in next paper

Study of nanocomposites based on cellulose nanoparticles and natural rubber latex by ATR/FTIR spectroscopy: The impact of reinforcement

2018 ◽  
Vol 40 (5) ◽  
pp. 2076-2087 ◽  
Author(s):  
Fatma Agrebi ◽  
Nouha Ghorbel ◽  
Serge Bresson ◽  
Ouissam Abbas ◽  
Ali Kallel
Keyword(s):  
Natural Rubber ◽  
Ftir Spectroscopy ◽  
Natural Rubber Latex ◽  
Rubber Latex ◽  
Cellulose Nanoparticles ◽  
The Impact
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