Natural Rubber Latex Films Research Articles

Effect of Ball Milled and Ultrasonic Sago Starch Dispersion on Sago Starch Filled Natural Rubber Latex (SSNRL) Films

The methods of dispersions preparation play a role in reduction of the particle size of the prepared dispersion. In the natural rubber latex compounding, the powder ingredients need to be dispersed before added in latex compounding to ensure the homogenous distribution in the compounds. In this study, two different methods of sago starch dispersion preparation, which are ball milling and ultrasonic were prepared. The effect of these methods on the mechanical properties of sago starch filled natural rubber latex (SSNRL) films was investigated. Particle size measurement test, scanning electron microscope (SEM) test and tensile test were carried out. The results showed that ball milling method has given smaller particle size and better dispersions compared to ultrasonic method. Thus, ball milled SSNRL film shown better mechanical properties due to the smaller size of starch particles.

Ion-Embedding for Soft Compliant Electrode Based on Natural Rubber Latex by UV Curing System

The soft compliant electrodes from the natural rubber latex as the matrix phase and the ionic filler solution as the dispersed phase by UV curing system have many advantages i.e. softness, flexibility, good appearance, compatibility, and good physical, electrical and mechanical properties. The electrical conductivity, Young’s modulus, tensile stress, critical strain, and curing time of soft compliant electrode added 0.5% V/V ZnCl2 ionic filler solution are 1.97 × 10-2 S/cm, 5.43 × 103 Pa, 6.97 × 104 Pa, 28.8%, 7 min. respectively. The electrical conductivity, Young’s modulus, tensile stress, critical strain, and curing time of soft compliant electrode added 0.75% V/V CuCl2 ionic filler solution are 3.26 × 10-2 S/cm, 3.03 × 103 Pa, 5.15 × 104 Pa, 6.84%, 7 min respectively. While the electrical conductivity, Young’s modulus, tensile stress, critical strain, and curing time of soft compliant electrode added 5.0% V/V CaCl2 ionic filler solution made from eggshell dissolved in HCl are 0.13 S/cm, 1.16 × 106 Pa, 7.92 × 105 Pa, 41.18%, 19 min. respectively. The electrical conductivity values of soft compliant electrode added with ZnCl2, CuCl2, and CaCl2 made from eggshell ionic filler solution are higher than that of cured natural rubber latex films without ionic filler solution with the magnitudes of 102 to 104. The eggshell is a calcium source used as the CaCl2 ionic filler solution which is potential for the soft compliant electrode and non-toxicity samples preparation. The soft compliant electrodes can be applied for various applications such as drug delivery, artificial muscle, robot, micro-pump, micro-valve, disk drive, flat panel speaker, linear motor in MRI, and etc.

Investigation of polymer degradation by addition of magnesium

ABSTRACTThe effect of alkali metal magnesium on polymer degradation of physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of Mg of different concentrations (0–30 ppm) to natural rubber latex and irradiation with various radiation doses (0–20 kGy). The radiation doses were optimized (12 kGy), and the adverse effect of Mg was studied against a reference film prepared without metal. Tensile strength, tear strength, and cross-linking density of the irradiated rubber films were decreased with increasing metal ion concentrations and decreasing radiation doses. The mechanical properties of the films were reduced by nearly 10% for 30 ppm Mg ions and at the optimum dose. In contrast, elongation at break, permanent set, and swelling ratio of the films were increased at the same conditions. The maximum tensile and tear strengths of irradiated rubber films without additive were 29.33 MPa and 47.95 N/mm, respectively, at a radiation dose of 12 kGy, and these values were about six times higher than those of blank samples. With the addition of Mg, the corresponding values decrease continuously, and the minimum values were found to be 26.35 MPa and 42.675 N/mm, respectively. The effect of divalent alkali metal on polymer chain scission can be explained by the classical electron concept reported in this article.

Effect of Filler Dispersion on Tensile Strength and Tearing Energy of Natural Rubber (NR) Latex Films

Fillers play important roles in enhancing mechanical properties of NR latex films. The effect of filler dispersion and amount of dispersing agent to the tensile strength and tearing energy of NR latex films were investigated in this study. The studies were carried out by (i) varying the amount of dispersing agent (Anchoid) added which is an anionic surfactant; and (ii) varying the speed of stirring during mixing of latex with compounding ingredients. It was observed that tensile strength and tearing energy were affected by both factors listed. In the case of NR latex film filled with 10 pphr of carbon black (Super Abrasion Furnace, SAF), the optimum stirring speed was 400 rpm and the optimum amount of surfactant was in the range of 5 to 10 % by weight. High tensile strength ranging from 29 - 31 MPa and high tearing energies ranging from 90.6 - 111.0 kJ/m2were achieved from optimization of these two factors; rendering their importance.

Characterizing Mechanical Properties of Peroxide-Vulcanized Natural Rubber Latex Films

Natural rubber latex is the material of choice for the fabrication of thin elastic films in many products such as gloves and condoms owing to its high strength, elasticity, comfort in use, good barrier properties and ‘green image’ [1, 2]. This unique combination of characteristics has its origins in the intrinsic properties of the crosslinked polymer network within the rubber matrix. The crosslinking of rubber hydrocarbon chains by free radicals generated from peroxide has been discovered for many years [3]. In peroxide crosslinking reactions, organic peroxide decomposes to produce reactive free radicals that will react to release hydrogen ions from the carbon hydrogen in the polymer chain, encouraging formation of free radicals on the rubber molecular chains. As the free radicals react with the polymer chains, the carbon hydrogen in the chains act as reactive centre that combines with centres of other rubber chains to form a network of carbon to carbon bonds which serve as crosslinks [3, 4].

Surface modification of natural rubber latex films by hydroxyethyl methacrylate

The surface modifications of natural rubber latex films by argon plasma pretreatment, followed by UV-induced graft copolymerization of hydroxyethyl methacrylate, were carried out to improve the latex hydrophilicity. The effect of plasma pretreatment time, monomer concentration and UV irradiation time on the graft densities was studied. ATR-FTIR analyses indicates the efficient grafting of poly(hydroxyethyl methacrylate) onto the surface of latex film. The surface roughness of natural rubber latex films increases to 360 nm from 9 nm, leading to a decrease of water contact angle value of NR latex film surface to about 60° from 100°, and thus confirmed improvement of the hydrophilicity of latex film. Biocompatibility of the film was evaluated with vitro cytotoxicity test; the results proved a good biocompatibility of modified latex.

Validation of an Electronic Sensor Network (ESN) Control Chamber for Monitoring the Soil Decomposition Process of Sago Starch-filled Natural Rubber Latex Films

Abstract Biodegradable sago starch-filled natural rubber latex films were subjected to soil decomposition. Decomposition indicators such as temperature, soil pH and humidity, and volume of carbon dioxide and oxygen were monitored via an electronic sensor network (ESN) control chamber. During the assessment, the environmental temperature was kept constant and a small increase in soil humidity was detected. The ESN control chamber detected the increment of soil pH and carbon dioxide level and a decrease in oxygen content during the biodegradation process. The changes in these parameters confirmed the progress of the biodegradation process. The mass loss retention for films was compared with data obtained from the ESN control chamber to get the coefficient of correlation (r) value, which describes the relationships between the two datasets. Scanning electron microscopy images confirmed the formation and growth of microorganism colonies, and Fourier transform infrared analysis indicated the breakage of double-bonded carbon in sago starch-filled natural rubber latex films and carbonyl group intensification, signifying the formation of aldehyde and ketone groups after the fourth week of soil decomposition.

Effect of Drying Time on Mechanical Properties of Natural Rubber Products Filled with Modified Kaolin Prepared from Latex Dipping

Alkanolamide-modifed kaolin was added into natural rubber latex (NRL) pre-vulcanization system at 70°C and the products were formed into films by coagulant dipping method. The dipped films then were dried at 120°C for 15 and 30 min. The effect of drying time on properties of NRL films such as crosslink density, tensile strength, tensile modulus, and elongation at break was observed in this study. Results showed that longer drying time improved the properties of NRL films due to the additional formation of crosslink process in the NRL films. The longer drying time swelled the particles more in matrix as confirmed by Scanning Electron Microscopy (SEM) micrograph.

Effect of Aging on Mechanical Properties of Natural Rubber Latex Products Filled with Alkanolamide-Modified Cassava Peel Waste Powder (CPWP)

The effect of aging on mechanical properties of natural rubber latex (NRL) products filled with alkanolamide-modified cassava peel waste powder (CPWP) was studied. CPWP used as fillers was prepared by milling and sieving it until the size of 100 mesh. The powder then was dispersed in a suspension containing water and alkanolamide in order to modify the prepared powders. The dispersion system of 10 pphr (part per hundred rubber) then was added into NRL matrix followed by pre-vulcanization at 70°C for 10 minutes. The NRL compound then were casted into films by coagulant dipping method then dried at 120°C for 10 minutes. Afterwards, the films were allowed to cool at room temperature for 24 hours before being aged in a circulation of hot air for 24 hours at 70°C. The properties such as tensile strength, tensile modulus, and elongation at break were evaluated between the aged samples and the unaged samples. From this study, it showed that the aged films have increasing value of tensile strength and tensile modulus while the value of elongation at break decreases. These datas are supported by Scanning Electron Microscope (SEM) micrographs which indicate that the change of morphology in NRL films occurs before and after aging.

Effect of Micro and Nano Zinc Oxide on the Properties of Pre-Vulcanized Natural Rubber Latex Films

Zinc oxide (ZnO) nanoparticles were synthesized through a solution free mechano-chemical route and their effects on pre-vulcanized natural rubber latex properties were investigated. Effect of nano ZnO loading on swelling, antimicrobial, mechanical and ageing properties of pre-vulcanized latex vulcanizates were examined and compared with conventional micro ZnO filled vulcanizates. In comparison with micro filled system, nano filled system exhibits better performance in all respects. The ageing resistance of nano ZnO incorporated latex films was found to be high.

Enhanced antibacterial activity of NR latex gloves with raspberry-like PMMA-N,N,N-trimethyl chitosan particles

Raspberry-like poly(methyl methacrylate) (PMMA) latex particles stabilized with silica nanoparticles (SiNPs) were prepared via the Pickering emulsion polymerization for use as substrate of N,N,N-trimethyl chitosan (TMC) adsorption. With the aims to simultaneously reduce the surface friction and improve the antibacterial activity of rubber gloves, the synthesized PMMA-SiNPs(TMC) particles were electrostatically deposited onto a sulphur prevulcanized natural rubber (SPNR) latex film. From SEM and AFM analyses, the results showed the highest surface coverage of PMMA-SiNPs(TMC) particles on the surface of SPNR film of 41% and the surface roughness of 69nm. The coated SPNR film exhibited effective antibacterial activity especially against S. aureus. Therefore, this investigation would be useful for fabrication of special gloves with antibacterial properties.

Influence of Modified Cassava Peel Waste (CPW) Loading on Tensile Properties of Natural Rubber Latex (NRL) Products

Cassava peel is one of agricultural waste that abundantly found in environment. One approach to manage this waste is to apply it as filler in natural rubber latex. In this work, the cassava peel waste (CPW) was powdered and dispersed in alkanolamide-water dispersion system to modify its surface. The amount of fillers used was 0, 5, 10, 15, 20 and 25 phr (part per hundred rubber) and loaded in natural rubber latex (NRL) formulation system. The products then were formed by dipping method after the NRL formulation was pre-vulcanized at 70°C. The observed parameter includes crosslink density, tensile strength, tensile modulus and elongation at break. Scanning Electron Microscope (SEM) was used to study the morphology of tensile fracture in NRL film. The results show that 10 phr loading of modified fillers increases the crosslink density, tensile strength, and tensile modulus but decreases the elongation at break. SEM study also reveals that higher filler loading above 10 phr will create the agglomeration in rubber matrix.

Effect of Manganese on Radiation Vulcanization of Natural Rubber

Manganese was added as a promoter to investigate physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films. RVNRL films were prepared by the addition of Mn with the concentration range 0–30 ppm to natural rubber latex and irradiated with various radiation doses (0–20 kGy). Tensile strength, tear strength, and cross-linking density of the irradiated rubber films increased with increasing the concentration of Mn ions as well as radiation doses. In contrast, elongation at break, permanent set, and swelling ratio of the films were decreased under the same conditions. The concentration of Mn ions and radiation doses were optimized and found to be 20 ppm and 12 kGy, respectively. The maximum tensile and tear strengths of irradiated rubber films were observed as 29.12 MPa and 44.78 N/mm, respectively at the optimum conditions. The mechanical properties of the films increased markedly with the addition of Mn until they attained the highest values of 33.88 MPa and 54.77 N/mm, respectively. These enhancements, which reached approximately 20% at the most favorable conditions, can be explained by the effect of transition metals in view of Fajan’s rules regarding the covalent character of ionic bonds and suggest that the higher the difference in charges between cation and anion, the higher the ability to form distortion or polarization of ions.

Effect of Poly (Butyl Acrylate) and Poly (Ethylene Oxide) Modified Sago Starch on Natural Rubber Latex Films Physical Properties

Sago starch is modified with 1 wt % Poly butyl acrylate (PBA) and Poly ethylene oxide (PEO) monomer and 1 wt% of initiator, potassium persulfate (PPS) at temperature 80°C for 2 hours. Modified sago starch is cooled under room temperature for 24 hours prior to Natural Rubber Latex (NRL) compounding process. Results indicates that NRL films with PBA modified sago starch have higher mechanical properties compared to PEO modified sago starch and unmodified sago starch. Swelling test indicates that PEO gives lowest percentage of swelling and crosslink density. This is due to higher reaction probability that produce more closely packed structure with NRL matrix compared to PBA which only improved the compatibility of sago starch particle with rubber matrix. Thus, chemically modified sago starches are preferable to be used as fillers to produce better interaction between fillers and rubber matrix.

Natural Latex Films as Carrier for Casearia sylvestris Swartz Extract Associated with Ciprofloxacin

In order to create a new sustained drug delivery system applied for tissue regeneration, this study beget a natural rubber latex (NRL) film with Casearia sylvestris extract and ciprofloxacin. Manipulated from the biomaterial latex obtained by the rubber tree Hevea brasiliensis , the NRL film has shown to be a great angiogenic compound and also has shown a great potential in being a possible carrier for sustained drug release. In order to increase the therapeutic spectrum of the film two substances was added to it: the C. sylvestris extract which has antiulcer, anti-inflammatory and Original Research Article

Preparation of Positively Charged Membrane from Natural Rubber Latex Blending with Chitosan

Film formation of natural rubber latex (NRL) blended with various concentrations of chitosan was investigated. Atomic force microscopy (AFM) images clearly showed that the NRL film covered chitosan phase. Roughness of the films which was calculated from AFM image increases with increasing chitosan concentration. Miscibility of NRL and chitosan in solution was investigated by using dynamic mechanical thermal analysis (DMTA) and found that chitosan incorporated with NRL less than 40 weight percentage (wt%) was partially miscible. Films of the chitosan blending with higher NRL contents exhibited two peaks of glass transition temperatures. Interfacial polarization and dielectric properties of polymer films were improved with increasing NRL contents. Chemical structure of the blends was characterized by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).

The Influence of Starch Gelatinization on Mechanical Properties of Natural Rubber Latex Films

The addition of starch in natural rubber (NR) latex films tends to decrease the mechanical properties of NR latex films due to poor dispersion of the fillers. As an alternative, starch was gelatinized before being added into NR latex compounds. The dispersion of 10% starch was mechanically prepared through ball milling together with dispersing agent. The other dispersion of 10% starch was gelatinized using alkali. The influenced of ball milled starch and alkali gelatinized starch filled NR latex films were studied through scanning electron microscopy, tensile properties, tear strength, and swelling properties. The rough freeze fracture surface with less agglomeration of fillers was observed on the alkali gelatinized starch NR latex films. The NR latex films filled with alkali gelatinized starch showed improvement in tensile properties, tear strength, and swelling resistance compared to the ball milled starch NR latex films. It can be concluded that the alkali gelatinization improved the dispersion of starch in NR matrix thus enhanced the mechanical properties of NR latex films.

Effect of Different Thickness of Core Layer on Tensile Properties of Laminated Natural Rubber Latex Film

Laminated natural rubber latex with cleaning agent and waste latex compound was prepared by arranging half-cured latex sheets with various thicknesses of core layer then moulding using hot press according to the Rheometer graph. Laminated layers consist of outer layer (natural rubber latex films with cleaning agent) and core layer (waste natural rubber latex film). The core layer and outer layer are prepared through casting method with different thickness. For core layer, three different thickness of film is cast and for outer layer the thickness is control. The aim of this paper is to study the effect of different thickness of core layer and the different molding temperature on tensile and swelling properties of laminated films. The tensile test was carried out to acquire good interfacial adhesion between the laminates films. The fractured surface morphologies were carried out using digital microscope (Dino-Lite) to understand the interfacial interaction between core and outer layer of the films. The use of NRL lamination films with NRL waste will contribute to novel materials for as mould cleaning product with green and easier cleaning compare to conventional cleaning process.

Reinforcement of Natural Rubber Latex Film by Starch Nanocrystal

Starch nanocrystals obtained from acid hydrolysis, and the starch/natural rubber latex film was prepared by blending the starch nanocrystals with natural rubber latex. The latex properties such as viscosity and mechanical stability, water and toluene uptake, crosslinking density and mechanical properties of the latex films were investigated. The results showed that the mechanical stability of natural rubber latex reinforced by starch nanocrystals increased, but the change of viscosity was not obvious. By adding starch nanocrystals in natural rubber latex, the swelling by toluene decreases and the swelling by water increased. The mechanical properties and crosslinking density of films were enhanced with the increase of starch loading.

Contribution of hydrogen and/or covalent bonds on reinforcement of natural rubber latex films with surface modified silica

ABSTRACTA macromolecular coupling agent containing hydrophilic and hydrophobic groups is made to react with precipitated silica. Interfacial interactions between OH groups of silica and COOH groups of macromolecule are found to be created through either hydrogen bonds alone or through hydrogen bonds and covalent bonds. Aqueous dispersions of unmodified and modified silica are prepared and the colloidal stability and particle size distribution of the dispersions are observed. The dispersions at neutral pH are incorporated into vulcanized/unvulcanized natural rubber latex. The formation of hydrogen bonds and/or covalent bonds is studied via FTIR spectroscopy and their contribution in encouraging filler‐rubber interactions is emphasized through mechanical and swelling properties. Uniform distribution and dispersion of modified filler particles throughout the rubber matrix is confirmed by the microstructures of the latex films cast from filler added natural rubber latex. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40380.