Concentrated Latex Research Articles

Desulfurization of H2S‐rich biogas using water scrubbing: Performance in pilot scale scrubber and scale‐up estimation for the concentrated latex factory

AbstractA high about 3% H2S concentration in the biogas produced from concentrated latex process wastewater needs to be removed before further utilization. Water scrubbing is appropriate for the latex factory having plenty of recycled water available. Effects of liquid to gas (L/G) ratios at 0.5–4.0 on H2S removal were tested at 0.06 m3/h biogas flow rate using a pilot scale scrubber. The experimental results were then simulated to validate the scale‐up for the factory, using the process simulation software Aspen HYSYS (HYSYS, Hyprotech and Systems). The highest 99.71% H2S removal was obtained by using L/G ratio 4.0. Interestingly, using L/G ratio 1.0 provided 96.01% H2S removal, which is slightly lower than on using L/G ratio 4.0, but is more practically appropriate for the real volumes of recycled water and biogas generated from the factory. The experimental data agree with the simulations well. The packed column diameter and height were estimated as 0.5 and 3 m for 40 m3/h biogas. Key characteristics of the scrubber effluent were analyzed for further discharge management. The scrubber effluent qualified for direct discharge to the post‐treatment ponds. This work shows that using recycled water for desulfurization of the H2S‐rich biogas is feasible at atmospheric pressure operation.

Fast determination of total solids content (TSC) and dry rubber content (DRC) of para rubber latex using near-infrared spectroscopy

A rapid measurement method of total soluble solids content (TSC) and dry rubber content (DRC) of para rubber latex (PRL) is required for trading and production control purposes. The objective of this study was to develop the TSC and DRC prediction model of a PRL sample based on the near-infrared (NIR) spectroscopy method. The samples were scanned using the transflectance method, wherein the effect of the pathlength to model accuracy and precision were investigated. NIR spectra were collected, incorporating a wavelength region of 860–1760 nm. The models were developed using partial least squares (PLS) regression with either raw spectra or spectra pre-treated by a baseline offset, a standard normal variate (SNV), multiplicative scatter correction (MSC), and a fractional order derivative (FOD). The results of the TSC model developed using NIR spectra from a 8 mm pathlength had the highest performance, with R2p, RMSEp, Bias, and RPD of 0.97, 1.15%, 0.43% and 6.17, respectively. Meanwhile, the NIR spectra from a 4 mm pathlength developed with a FOD at 0.25 gave the best performance in DRC prediction, whose R2p, RMSEp, Bias, and RPD were 0.96, 1.20%, − 0.52% and 5.40, respectively. Therefore, the author concluded that the developed models could be used to evaluate the TSC and DRC of a PRL sample as a real-time method in factory.

Experimental Study on Mechanical Properties of Cement Doped with Different Latex Contents

Experimental Study on Mechanical Properties of Cement Doped with Different Latex Contents

Nutritional Content and Antimicrobial Activities of Latex from Artocarpus heterophyllous Lam. on a Few Bacterial and Fungal Species

Nutritional Content and Antimicrobial Activities of Latex from Artocarpus heterophyllous Lam. on a Few Bacterial and Fungal Species

Thiol‐ene emulsion step polymerization in a photochemical stirred tank reactor: Molecular weight, cyclization, and fragmentation

AbstractUnlike many step polymerizations, the polymerization of bifunctional thiol and alkene monomers can be carried in emulsion to prepare a range of sulfur‐containing polymer particles differing markedly from conventional emulsion chain polymers. This study examines how the change of polymerization mechanism affects polymer molecular weight, structure and composition. A 2,2′‐dimercaptodiethyl sulfide/diallyl phthalate emulsion is photopolymerized in a photochemical stirred‐tank reactor equipped with Light‐emitting diodes (LEDs) to yield a 30% solids content latex with a high weight‐average molecular weight (100 kDa) and a broad molecular weight distribution (Đ = 8.5). Intramolecular cyclization occurs during polymerization by the addition of a thiyl radical to the unsaturated end group of the same molecule. Irreversible ring‐closure takes place to produce “dead” cyclic oligomers in the early stage of the reaction, whereas chain‐growth continues at high conversion. Consequently, the particles are composed of high molecular weight linear chains and a fraction of stable oligomer cycles, showing a broad and bimodal molecular weight distribution. The linear poly(thioether) chains include occasionally disulfide units due to thiyl radical recombination. The reversibility of disulfide bonds causes a decrease of molecular weight during storage. The addition of radical inhibitor to the latex stops fragmentation of SS bonds.

Isolation, purification and partial characterization of ficin from Ficus carica latex

This study aimed at the isolation, purification and characterization of fig latex ficin. Samples were collected from fruit joint with the fig tree. Supernatant was decanted from fig latex after centrifugation at 3000 rpm which represents crude enzyme extract. Latex content was concentrated by sucrose powder. Purification steps were carried out with ion-exchange and gel filtration using DEAE- cellulose and sephadex G-50 columns respectively. Enzyme yield and purification folds were 51.688% and 15.635 respectively with specific activity 148.336 U/mg. By using gel filtration, molecular weight of the purified enzyme was estimated to be 22.725 Da. The pH at which ficin showing activity ranged between 6-8.5. Ficin showed a good stability in pH ranging between 6-8. Optimum temperature for activity and stability were 50 C○ and 25-40 C○ respectively. Activation energy for substrate conversion of this enzyme was calculated to be 10.22 Kca/mol.

Performances of UHPC bonded cementitious composite systems containing styrene-butadiene rubber latex in a chloride-rich environment

• The green and sustainable cement-based material—UHPC was used as the repairing material to strengthen the existing cementitious substrate. • Mechanical, electrochemical and microstructural characteristics of the bonded composite systems were investigated. • The performance developments of the composite systems in a chloride-rich environment were presented. • Styrene-butadiene rubber (SBR) latex were considered to enhance the bonding properties and the electrochemical performances of the composite systems. This study investigates the mechanical, electrochemical and microstructural characteristics of UHPC bonded cementitious composite systems concerning the influences of chloride attack. The bonded composite systems with styrene-butadiene rubber (SBR) latex content of 0, 2 %, 4 %, 6 %, 8 % in UHPC layers were prepared. The experimental groups were immersed in saturated sodium chloride solution whereas the reference groups were cured in clean water. The compressive, bonding and flexural strength of the bonded systems were tested at different curing ages. The free corrosion potential, AC impedance spectroscopy and polarization resistance were considered to figure out their electrochemical behaviors. Furthermore, X-ray diffraction (XRD), pore structure characteristics as well as scanning electron microscope (SEM) observations were employed to show some light on the internal mechanism at a microscale level. Results indicate that the chloride-rich environment demonstrated certain adverse effects on the system’s mechanical properties, especially the bonding strength, which could be reduced by 20 % on average at 56d. Proper content of SBR latex was conducive to the system’s bonding strength. However, when the dosage was too large, a remarkable adverse effect on compressive strength was seen. The addition of SBR latex could further delay the corrosion of the reinforcement inside the system, from 28d of the systems without latex to 42d with 4 % SBR latex. The microstructural investigations confirmed that in a chloride-rich environment, the total pore volume was reduced by 29.4 % at 28d. A dense transition zone was observed between the substrate and the UHPC layer with a width of about 0.1 μm in clean water curing, whereas it became relatively loose and obvious bonding holes appeared in this area under severe chloride attack.

Synthesis of low crystalline thermally insulating calcium silicate hydrate via a simple template-assisted sol–gel method

Internally structured porous calcium-silicate-hydrate (CSH) particles were made by a simple template-assisted sol–gel process involving an inexpensive and renewably produced templating material (skimmed natural rubber (NR), a waste generated during production of concentrated rubber latex) and a cheap silica source (sodium silicate). The CSH particles were then added to cement to produce mortar with excellent thermal insulation performance. Effects of the following factors on morphology, porosity, crystallinity and thermal insulation performance of CSH and CSH-mortar were studied: the CSH synthesis parameters (time and temperature for hydrothermal aging; the NR/silica mass ratio) and CSH/cement mass ratio in mortar. The CSH particles produced were mainly amorphous. The tobermorite and truscottite phases developed as both the time and temperature of hydrothermal aging were increased; however, a high value of NR/silica mass ratio hindered crystallization. Irrespective of the presence of crystalline phases, CSH particles improved the thermal insulation performance of mortars. The crystallization affected the meso- and macropores within the CSH solids and contributed to enhancing their thermal insulation performance. The NR template was crucial to develop the porous structure that enhanced the thermal insulation performance of CSH and the mortar incorporating it.

In Silico Pharmacokinetic Profiling of the Identified Bioactive Metabolites of Pergularia tomentosa L. Latex Extract and In Vitro Cytotoxic Activity via the Induction of Caspase-Dependent Apoptosis with S-Phase Arrest.

The in vitro cytotoxic efficacy of plant latex from Pergularia tomentosa L. was studied using five human cancer cell lines: HeLa cells (cervical carcinoma cells), A-549 (lung carcinoma), Panc-1 (pancreatic carcinoma cells), MDA-MB-231 (metastatic mammary adenocarcinoma), and MRC-5 (lung fibroblast cell line) cells. The phytonutrient content of plant latex was identified using the liquid chromatography/mass spectra-quadrupole time of flight (LC/MS-QTOF) technique. In silico studies of polyphenols were carried out to clarify the potential mode of action of the plant latex’s constituents. The treatment of different tumor cell lines with different concentrations of plant latex revealed a potent efficacy on the human lung carcinoma cell line (A-549) (IC50 = 3.89 µg/mL) compared with that with vinblastine as a positive control (IC50 = 7.12 µg/mL). The effect of the potent concentration of plant latex on the A-549 cell line induced cell arrest, upregulated the expression of pre-apoptotic markers, and downregulated the expression of antiapoptotic markers. Seven identified polyphenols were selected for the in silico study. A docking assessment using the epidermal growth factor receptor kinase (EGFRk) and eltronib as a positive control showed a higher affinity for the enzyme receptor of the selected polyphenols, except for methyl orsellinate and ginkgotoxin. The ADMET assessment demonstrated the inhibitory effect of the polyphenols on CYP450, except for ouabagenin and xanthyletine. The selected polyphenols obey Lipinski’s drug-likeness with no significant toxicity effect. In conclusion, the plant latex of P. tomentosa L. showed cytotoxic activity on the A-549 cell line, and the selected polyphenols showed a promising prodrug agent with a low profile of toxicity in the study.

Nanoscale polymer encapsulated pigment hybrid latexes with high pigment content for binder-free pigment printing of cotton/polyester blend fabrics

Pigment printing of cotton/polyester (C/P) blend fabrics is an environment-friendly technology for achieving cleaner fabric coloration. However, the application of conventional pigment-printing technology is restricted owing to the stiff feeling and low crocking fastness of the printed goods. In this study, a novel polymer-encapsulated pigment hybrid latex with nanoparticle morphology and high pigment content was synthesized for binder-free pigment printing of C/P fabrics via sulfur-free reversible addition-fragmentation transfer (SF-RAFT) emulsion polymerization using allyloxy polyoxyethylene (10) nonyl ammonium sulfate (DNS-86) as the reactive surfactant. The pigment content of the hybrid latex was as high as 83.8%, with an average particle size of 251 nm. The surface of single C/P fibers was uniformly wrapped by the hybrid latex film, where the highly encapsulated pigment accelerated pigment fixation on the fibers, improving the color depth, color fastness, air-permeability, and hand-feel of the binder-free printed C/P fabrics in comparison with those of the control system with low pigment content (traditional free radical polymerization). More importantly, the highly encapsulated pigment hybrid latex particles promoted the formation of a new discontinuous film coating on the surface of single fibers, which opens up a promising avenue for replacing conventional fabric printing techniques.

Evaluation of Latex Polymeric mortar properties for laying bricks in non-structural masonry

Polymeric mortars (PM) or Latex Polymeric mortars are a class of building material that can replace Portland cement mortar. PM are produced with polymer resin, which acts as a binder that allows excellent bonding between brick layers. The goal of this study was to evaluate polymeric mortars based on poly (styrene-acrylic ester) latex, water based, cementless and ready to use in laying bricks in non-structural masonry. The polymeric mortars were obtained with different polymer contents, starting with a minimum value of content. The properties were evaluated using different techniques aiming to find the most suitable techniques to analyze these new materials. The mortars were characterized by the consistency in the fresh state, mechanical properties (tensile and compressive strength), thermal properties, thermal resistance and the swelling degree. SEM and optical microscopy showed that surface morphology and porosity distribution varied with change in resin content. Thus, most of the analyzed properties are sensitive to variations of the polymeric latex content. Small increments in the formulation increased mechanical properties, making the material obtained more compatible and suitable for commercial application. In general, the mortars showed different porosity for high and low polymeric latex content. The methodologies used to characterize the mortars showed to be adequate for the new material, except for the shear strength in ceramic blocks, which showed the rupture of the blocks instead of the mortar.

EFFECT OF AMMONIA AND COD TO SULFATE RATIO ONTREATMENT PERFORMANCE OF CONCENTRATED LATEXPROCESSING WASTEWATER

The objective of this study is to investigate the effects of ammonia nitrogen (NH3-N) and COD to sulfate ratio on the treatment performance of concentrated latex processing wastewater (CLPW). In a batch experiment, the CLPW influent COD, % granular sludge and pH were controlled at about1,200 mg/l, 10% and 7, respectively. The influent NH3-N concentrations varied at 100, 500, 1000 and3000 mg/l, whereas COD/sulfate ratio varied at 0.3, 0.6, 1 and 1.3. Treatment performance was determined by methane generation rate and COD removal efficiency at different NH3-N and COD to sulfate ratio. The NH3-N concentration at 100 and 500 mg/l (which were presented in the real CLPW), did not result in inhibition on methane producing bacteria (MPB), since methane generation was detected. Inhibition on MPB was observed at 1,000 mg/l NH3-N. Strong inhibition occurred at 3,000 mg/l NH3-N, since % COD removal was relatively reduced to 7.98 % and nomethane generation. The COD/sulfate ratio at lower than 0.6 resulted in inhibition of MPB, but in the real CLPW the ratio is normally higher than 0.6. Ammonia concentration higher than 1000 mg/l and COD to Sulfate at lower than 0.6 resulted in inhibition of methane producing bacteria in the treatment of CLPW.

Investigation of Field Performance and Film Properties of Natural Rubber Latex Preserved with a Novel Chemical

The traditional long-term preservative system of latex has an impact on environmental air pollution by ammonia and leads to the production of carcinogenic nitrosamine substances by tetramethyl thiuram disulfide (TMTD). In this research, ammonia and a novel preservative with a polysulfidic link were compounded and tested as a novel traditional long-term latex preservative system, to overcome the drawbacks of traditional preservative systems. Control samples were prepared with ammonia as the standard preservative. In addition, ammonia and the novel chemical mixed samples were also prepared for investigating the combined effect. After the preservation treatment, the stable nature of field NR latex was evaluated via the Volatile Fatty Acid (VFA) test based on ASTM D 1076 standard. The Dry Rubber Content (DRC) test and Total Solid Content (TSC) test were carried out for VFA calculation purposes based on ISO126:2005 and ASTM D 1076 standards, respectively. The alkalinity test was carried out to maintain the required ammonia content in latex. In the first trial, traditional dispersion preparation of novel chemical dispersion failed due to the large particle size of the novel chemical. Therefore, two different novel chemical dispersions were prepared in the second trial, where dispersions 1 and 2 were prepared with wetting agents and without using a wetting agent, respectively. It was found that 0.020%v/v and 0.025% v/v concentrations of the novel chemical from dispersion 1 allowed the preservation of field NR latex for 8 days. A low concentration (0.015% v/v) of the novel chemical was able to keep latex with good stability for 5 days. The novel chemical dispersion without a wetting agent exhibited a marvelous preservative system to NR latex than with a wetting agent, because the wetting agent creates a barrier between particles of novel chemical and latex particles. The novel preservative acts as a good preservative while reducing the fumes of ammonia being emitted and eliminating the carcinogenic nitrosamine emission from TMTD.

Influence of Non-Rubber Components on the Properties of Unvulcanized Natural Rubber from Different Clones.

Natural rubber from different Hevea braziliensis clones, namely RRIM600, RRIT251, PB235 and BPM24, exhibit unique properties. The influences of the various fresh natural rubber latex and cream concentrated latex on the non-rubber components related properties were studied. It was found that the fresh natural rubber latex exhibited differences in their particle size, which was attributed to the non-rubber and unique signature of clones which affect various properties. Meanwhile, the cream concentrated latex showed the protein contents, surface tension, and color of creamed latex to be lower than the fresh natural latex. However, TSC, DRC, viscosity, particle size and green strength of concentrated latex were found to be higher than the fresh natural latex. This is attributed to the incorporation of HEC molecules. Also, the rubber particle size distribution in the RRIM600 clone exhibited a large particle size and uniform distribution, showing good mechanical properties when compared to the other clones. Furthermore, the increased green strength in the RRIM600 clone can be attributed to the crystallization of the chain on straining and chain entanglement. These experimental results may provide benefits for manufacturing rubber products, which can be selected from a suitable clone.

Dynamic water penetration behavior of top coating color and its effects on structure properties of double-coated layer

The relationship between the dynamic water penetration behavior of top coating color and double-coated paper properties, including pore structure, surface roughness, gloss, and surface latex content, was investigated. Top coating was applied onto the precoated paper prepared using different pigment types, thereby having different pore structures. To investigate the effect of dwell time on pore structure and surface latex content, coating speed and the distance between two coating heads of a laboratory coater were adjusted. As the number of pores of the precoated layer increased, the amount of water that penetrated the precoated paper increased, regardless of low shear viscosity of the top coating color. The relative pore ratio and surface properties of the top coated layer were proportional to those of the precoated layer. A UV absorbance analysis was conducted to examine latex binder migration. The latex content on the surface of the coating layer was mainly affected by the dwell time to the dryer after coating.

Enzymatic approach in accelerating colloidal stability of concentrated natural rubber latex and its effect on rubber products

In this work, enzymatic treatment was thoroughly investigated as an environmentally benign method for accelerating the colloidal stability and maturation rate of concentrated natural rubber latex (CNRL). It was found that the treatment of CNRL with lipase, an enzyme that catalyze the hydrolysis of lipids and phospholipids, was much more effective in boosting the colloidal stability of CNRL than the use of commercial ammonium laurate soap without causing an over-stabilized problem at longer time. The investigation of lipase treatment in CNRL obtained from different production lots indicated that the lipid content in CNRL was the key parameter in determining maturation rate of lipase-treated latex: the latex lot with higher lipid content could be maturated faster. Moreover, lipase treatment could also reduce the use of ammonia by at least 50% (from 0.6 to 0.7 to less than 0.29 wt%) and could completely replace the use of zinc oxide and tetramethylthiuram disulfide (TMTD), a carcinogenic chemical commonly used in low-ammonia latex, without affecting its colloidal stability. For the effect on the downstream processes, it was found that lipase treatment did not cause any adverse effect to downstream product-forming process but could also lead to stronger cross-linking bonds and better rubber product quality.

The Effect of Type of Vibration to the Quality of Concentrate Latex on the Creaming Process

So far, the manufacture of concentrated latex still requires expensive equipment investment if using the centrifugation method and requires a long time if using the creaming method. Therefore, two prototypes of creaming equipment with orbital and horizontal vibrations have been designed, which are expected to produce concentrated latex with a fast creaming time using simple equipment. This study aimed to obtain a type of vibrator that can produce concentrated latex according to the ISO 2004 quality standard. The experimental design used a nonfactorial, Completely Randomized Design, namely the treatment of orbital vibrators and horizontal vibrators. This equipment worked at a speed of 114 rpm for 6 hours and a creaming time of 63 hours. The results showed that the concentrated latex produced using a horizontal vibration had a better quality when compared to using a linear vibration with a DRC value of 66.67%, pH 10.8, TSC 67, 61% and MST 1078, 2 seconds. This value has entered the ISO 2004 quality standard.

Utilization of Natural Rubber (Latex) as Raw Material for Flexible Pavement Industry

The rapid development of structures so far needs to be balanced with road construction, but there are many road damages that use asphalt flexible pavements are damaged and changes or deformations in the pavement, this can be caused by the influence of heat, radiation, rainfall, volume or high traffic loads and will be overcome with the addition of natural rubber to reduce the bad things above. The research implemented.at the Road and Bridge Laboratory and the Lampung State Polytechnic Analysis Laboratory for 6 months. The treatment that will be applied in this research is the manufacture of additives with the creaming method in the Analysis Laboratory which finally concentrates latex with variations of 3%, 5% 7 and 9% of the weight of pure asphalt which will be applied with asphalt and aggregate materials. pavement to form a denser bond. Variations in making samples using the FCR (Design Mixed Formula) method or DMF design mix formula, using concentrated latex as an additive and testing using the Marshall Test testing method in road and bridge laboratories so that from the research results obtained for asphalt and latex the treatment has an effect on the value MQ (Marshall Quotient), but the interaction results show that the ANOVA table shows that asphalt, latex and the interaction between asphalt and latex show significant values. Duncan’s analysis with an alpha of 0.05 shows that the additives provide significant added value from the MQ (stability/Fatigue) kg/mm value and it is shown that the asphalt mixture with samples A and E after being mixed with additives gives a value according to the applicable standards in the table. requirement 2 for LL (traffic) Weight The min value of MQ 200 and the maximum of MQ 350 lies in a mixture of Type A 3% asphalt content and Type E with 9% asphalt content after adding latex and according to duncan’s analysis of the relationship between Asphalt Content and MQ Value. and for the best result for Flexible Pavement Industry Type A with 3% content can be recommended to be used

Deciphering the discoloration in the manufacturing of natural rubber

Many naturally occurring color components, especially non-rubber components, are present in natural rubber (NR) latex, limiting some NR applications, particularly for light-colored NR products in high demand. Non-rubber components, like lipids and proteins, can be removed from NR to reduce its yellow color. This study looked at the factors that influence the yellow index (YI) in NR and NR latex discoloration techniques. Proteins were a crucial factor directly determining the YI of NR. Thus, increasing the number of centrifugation washings, speed, and time was used to remove proteins to minimize the YI of NR. Percentage of total solid content (% TSC) of field NR latex, the blend ratio between cream rubber and skim latex, or bottom fraction from fresh-field NR latex collected from centrifugation process, were also important factors. The addition of sodium metabisulphites as a polyphenol oxidase (PPO)-reducing agent reduced the YI significantly. The oxidative breakdown of endogenous non-rubber components at high temperatures was also confirmed to serve the increase in YI value due to air-drying conditions of NR.

Freeze-gelcasting of aqueous alumina powder suspension using natural rubber latex

A new and non-toxic aqueous alumina gelcasting system using natural rubber (NR) latex as a gel former has been studied. A gel of reasonable strength is achieved by freezing concentrated alumina-NR latex co-dispersions in a mould followed by mould removal and aging in acetone. Gelation is achieved by coagulation of latex particles due to the breakdown of the protein layer on their surface during ice crystal growth. The minimum concentration of rubber required to percolate and form a soft and stable gel is 8 wt % of alumina. Aging of the frozen body in acetone for solvent exchange results in strengthening of the alumina-rubber gel network by further coagulation leading to reasonably high strength (∼60 kPa). The frozen body passes through a semi-fluid state during aging in acetone which enables the gel to reorganize and fill the space created by melting of ice crystals and thereby preventing the occurrence of pores in the green ceramics. The exchange of water in the gelled body with acetone enables easy and faster gel drying at room temperature. The diametrical compressive strength of the green body increases from 0.35 to 2.14 MPa during annealing at 200 °C due to the cross-linking of rubber. The cross-linked rubber in the green body undergoes near-steady state burnout without creating any crack. Debinding followed by sintering of the gelcast bodies at 1550 °C produce ceramics of ∼96% density. The sintered ceramics show a dense microstructure with an average grain size of 1.3 μm. The gelcasting using the NR latex is capable of producing complex near-net-shapes.