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Natural rubber foams were prepared from the vulcanization of natural rubber in a sulfur curing system at 396 K by a two roll mill with foaming agents; sodium bicarbonate (NaHCO3) or N, N'-dinitrosopentamethylene tetramine (DNPT, C5H10N6O2), and with 0, 20, 40, and 60 phr calcium carbonate (CaCO3) as a filler. The obtained natural rubber foams are l...
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... the amount of CaCO 3 fi ller particles increases, the relative foam density increases also. The crosslink density of the natural rubber foams is tabulated in Table 5. The crosslink density values for both foaming agents (NaHCO 3 and DNPT) decrease monotonically as the amount of CaCO 3 particles in- 3 219.0 ...
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... Advanced Materials and Biomaterials solvent was removed from the samples and thee samples were re-weighed as (W2). %Swelling of the prepared NR film were calculated by Eq. 3. Molar volume of the solvent (Vs), volume fraction of rubber in the swollen gel (Vr) and interaction constant (χ) are used for crosslink density (v) determination via Flory-Rehner relationship in Eq. 4 [5][6]. %Swelling and crosslink density of the film prepared from solution A are 639+3% and 5.82x10 -5 + 0.04 mol/cm 3 . ...
Easy wrap film has been widely used a single use film for dust free storage and COVID 19 prevention during the global pandemic. In the study, natural rubber (NR) latex was chosen as the domestic raw material for a coating application. Sulfur pre-vulcanized NR (PVNR) latex was prepared and purposely planned to be mixed with PVAc-co-PVA (Polyvinyl acetate-co-polyvinyl alcohol) or copolymer as the coating product for the proposed easy wrap film. Role of ratio between polymeric materials in physical, mechanical, thermal and weather resistant properties of the prepared films was elucidated. Ability of spark resistance of the easy wrap film prepared from the polymer mixtures prepared was tested.
... Isopropanol is also an organic BA with the lower decomposition temperature (83 ℃). Sodium bicarbonate is an inorganic BA which decomposes at 50℃ producing CO 2 and H 2 O and sodium carbonate (Tangboriboon et al., 2015 andKmetty et al., 2018). Natural rubber (NR) was selected as the polymeric material in this study due its natural availability and its renewable properties, in order to promote its usage replacing synthetic polymers, such as polyurethane. ...
... However there is no such support in the case of open cell structure which then leads to possible breaking of the cell walls providing higher compression values when compared to closed cell structures. The study conducted by Tangboriboon, et al., (2015) also reveals this trend with NaHCO 3 and DNPTBA. Figure 5 illustrates the effect of the BA and BA loading on the relative density of the cellular rubber compound. ...
... There is no uniformity in cell size when increasing the BA loading. Tangboriboon et al. (2015) and Charoeythornkhajhornchai, et al. (2016) have reported that cell size fluctuates when BA loading is increased. Ramesh, et al. (1991) stated that the size of the cell depends on the particle size of the BA and other chemical substances within the vulcanization process, temperature, pressure, and shear rate. ...
... While some disadvantages of gypsum ceiling without reinforcement are not practical due to brittleness, weakness in tension, low impact strength, and high-water solubility. Therefore, adding fillers such as fiber, particle, and structural reinforcement as composite materials can improve the mechanical, thermal, and physical properties of plaster products [8][9]. Gypsum powder acted as a matrix phase while the natural rubber latex compound functioned as a dispersed phase or reinforcement phase. ...
... The characteristics of natural rubber latex are sticky, milky, and white colloid. The distinct property of natural rubber latex is function as elastomer which after preparation, the processed natural latex has high tensile strength, good resilience, good elongation and toughness, high wear and tear resistance, and good thermal resistance [8][9]. ...
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.
... Industrially and commercially available natural rubber foam have mainly been manufactured via two methods depending on the starting rubber form including liquid rubber latex [168] or solid rubber. [169] The CBAs including oxydibenzenesulfonyl hydrazide (OBSH), AC, and sodium bicarbonate (NaHCO 3 ) are usually used to produce rubber foam. [170,171] Recently, an environmentally friendly physical foaming method has been developed by researchers to prepare microcellular rubber foam. ...
Elastomer foams have been widely used in many applications and have shown potential in some advanced fields because of their excellent flexibility. Elastomers foamed with a physical blowing agent solve the problems of traditional chemical foaming, endow elastomer foams with advantages of environmental-friendly features, uniform cell structure, adjustable material properties, and high processing efficiency. However, unlike foaming of thermoplastic materials, low matrix modulus and high gas diffusivity leads to serious foam post-foaming shrinkage and hinders the preparation of low density elastomer foams. In the past two decades, researchers have selected different elastomer systems and applied various foaming methods and strategies to prepare elastomer foams with improved performance through understanding the foaming mechanisms. This article reviews these investigations and discusses the developments made so far in physical foaming of elastomers.
... However, some of rubber products require the stiffness along with flexibility in certain applications, this can be achieved by adding filler to the rubber with certain size, amount and surface chemistry to suit the required applications. Several researches could be found in the literature study the influences of commercial fillers such as silica, carbon black, calcium carbonate and others on the properties of rubber/commercial fillers composites [3][4][5][6][7][8][9]. Furthermore, rubber/commercial filler composites were also used in rubber industry [10,11]. ...
In this work, Epoxidized natural rubber/sawdust short fiber (ENR-50/ SD) composites at different fiber content (5, 10, 15 and 20 phr) and size (fine size at 60-100 μm and coarse size at 10-20 mm) were prepared using the two-roll mill and electrical-hydraulic hot press machine respectively. Curing characteristics, water uptake, tensile, morphological, physical, and thermal properties of the composites were investigated. Results indicated that the scorch time and cure time became shorter whereas torque improved as SD content increase. Though the decline of tensile strength and elongation at break values, modulus, hardness and crosslinking density have shown enhancements with the increasing of SD content. The water uptake percentage of all samples has shown an increasing as SD content increase. However, the low SD content, particularly fine size have presented lower water uptake. The temperature of weight% loss (5 and 50 wt% loss) of 5 phr SD (low content) have recorded higher temperature compared to 20 phr SD (high content) in the rubber composites, which indicated higher thermal stability. The fine size of SD has recorded better overall properties than SD coarse size at the same loading in the rubber composites.
... Calcium carbonate (CaCO 3 ) in the form of chalk powder is widely used as filler in the production of building materials, plastics, rubber, paper, etc. (Thenepalli et al. 2010;Vogel et al. 2013;Tangboriboon et al. 2015;Hubbe and Gill 2016;Penkin et al. 2016;Lourenço et al. 2016;Lourenço et al. 2015b). At the same time, increasing requirements for chemical composition, dispersity and surface characteristics significantly narrow the application area of ground chalk due to its low consumer properties, such as lots of impurities, polydisperse composition, tendency to agglomerate, insufficient surface hydrophobicity, etc. ...
CaCO3 microparticles were obtained by chemical precipitation from CaCl2 solution using Na2CO3 or (NH4)2CO3 solutions (heterogeneous precipitation) or carbamide (homogeneous precipitation) as precipitation agents. The effects of various experimental conditions, such as the temperature, duration and reagent ratio on the properties of precipitated CaCO3 were experimentally investigated. It was found that the shape of particles and CaCO3 polymorphs depended on the precipitation agent and process temperature; the size of particles—on the reagent ratio, the precipitation agent and the deposition time. Biphasic calcite-vaterite spherical microparticles with the highest polydispersity coefficient (K = 0.98 with an average particle size ln ≈ 3 μm) were obtained using Na2CO3 solution as a precipitation agent under low temperature (20 °C). Calcite rhombohedral crystals (ln ≈ 3 μm) were obtained using carbamide at high temperature (100 °C). Increasing the temperature of Na2CO3 and (NH4)2CO3 solutions (70–100 °C) led to formation of the biphasic aragonite–calcite druses of needle crystals (druses size ≈ 10–30 μm). Increasing the aging time for sediments in the mother liquor up to 1 h did not affect the shape of CaCO3 particles.
... Substances that played an active role as blowing agents or foaming agents in the vulcanization process and caused the formation of rubber foam was N, N "dinitrosopentamethylene tetramine (DNPT) and NaHCO3 [9]. Najib et al. [10] reported that the difference in concentration of NaHCO3 added to NR as a blowing agent affected the foam morphology and the number of foam cells per unit volume. ...
... The cross linking formed by the fillers addition causes a slight difference in the compression set values for each formula as listed in Table 1. In addition, the filling material is added to the optimum ratio to maintain the elastic properties of rubber at a certain pressures and times [9]. ...
Modification of rubber-carbon-kaolin composite with sodium bicarbonate into sponges was carried out through the process of mastication, vulcanization and printing. The main ingredients consisted of natural rubber, carbon black, kaolin and sodium hydrogen carbonate. The research methodology was based on the development of composite rubber-carbon-kaolin by varying the composition of fillers which were kaolin and Sodium Bicarbonate. The results showed that mechanical properties of the modified sponge rubber-carbon-kaolin composite with sodium hydrogen carbonate for the formula B (Kaolin: Calcium Carbonate = 8:38 phr) had specific gravity of 0.51 g/cm³, compression set of 28,05%, tensile strength of 34,46 N/m³ and elongation at break of 212%. Based on the morphological analysis (SEM micrographs), the porosity of the composites was not homogenous. In addition, based on the thermal gravimetric analysis (TGA) there was a decrease in relative mass due to the differences kaolin and Natrium Bicarbonate loading.
... Salmazoa et al., (2016) telah melakukan penelitian karet busa dari karet alam dengan menghubungkan silang matriks polimer menggunakan sinar elektron energi tinggi pada dosis iradiasi yang berbeda (dari 50 hingga 150 kGy), busa yang diiradiasi pada dosis terendah struktur busa yang terbentuk lebih rentan terdegredasi, sementara busa disinari dengan dosis tertinggi menghasilkan struktur seluler yang lebih seragam. Tangboriboon et al, (2014) telah melakukan penelitian pengaruh natrium hidrokarbonat terhadap sifat mekanik karet busa yang menghasilkan kepadatan busa relative, crosslink densitas, pemampatan tetap, dan conductivitas thermal. Shey et al, (2006) telah melakukan penelitian sifat-sifat busa dari lateks dan pati, dimana pada penambahan aditif triton X-100 pada konsentrasi ≥ 0,05% mempunyai kemampuan untuk mencegah koagulasi. ...
... Several authors studied the effects of content and type of chemical blowing agent in elastomer. 4,5,13,14,22,23 Although Wimolmala et al. 5 and Sombatsompop et al. 22 studied the effect of azodicarbonamide content in the cellular NR system, the effect of azodicarbonamide content on the cure kinetics, kinetic parameters, thermal and physical properties of NRF has not been investigated yet. ...
The effect of azodicarbonamide as chemical blowing agent on the morphology, cure kinetics and physical properties of natural rubber foam is investigated. From the morphology, when the amount of chemical blowing agent increases from 3 to 4 phr, the bubble size in the rubber matrix slightly decreases due to the increase of vulcanization reaction rate from the presence of amine fragment species as by-products from the decomposition of azodicarbonamide. The coalescence between bubbles is observed in the specimen with 5 and 6 phr of azodicarbonamide owing to high gas content in the rubber matrix. Moreover, the scorch time slightly reduces and cure rate increases as a function of azodicarbonamide content. The autocatalytic model can be used to explain the curing reaction and mechanism of this natural rubber foam. Furthermore, the activation energy (Ea) directly relates to the bubble size and microvoid structure of natural rubber foam. When compared with the vulcanized natural rubber without adding chemical blowing agent, it is found that the bulk density of natural rubber foam significantly decreases and the volumetric expansion ratio of natural rubber foam increases at high content of chemical blowing agent. Moreover, natural rubber foam at 4 phr of azodicarbonamide exhibits the lowest thermal expansion coefficient due to the smallest bubble size with less coalescence.
... The porosity of the foam sample was determined by calculating the densities of solid and expanded foam using equation (8). In this study, an Archimedes water replacement method was used to measure the density of foam (Tangboriboon and Rortchanakarn, 2014). ...
Nowadays, green materials are of interest due to the changes of government policies in many countries towards sustainable product development. In this study, green rubber foam from reclaimed rubber glove at various sodium bicarbonate content (4, 6, 8, 10 and 12 phr) as blowing agent was prepared via melt compounding technique and expanded via two-step heat transfer foaming process. Compression testing and water absorption were performed and the results were then supported with morphological analysis. The crosslink densities determined using Flory-Rhener equation indicated the value had slightly decreased with increasing blowing agent. The 4 phr sodium bicarbonate generated the smallest cells and the highest relative density foam of 0.9. The foam exhibited the lowest water absorption rate of 1.7 × 10 g/min as well as the highest compressive strength of 105 kPa. Increasing blowing agent evidently increased the cell size and decrease the compressive strength of the foam.
