Liquid Rubber Research Articles

Influence of filler concentration and type on rheological and mechanical properties of liquid isoprene rubber for high-strength parts via material extrusion

This study investigates the rheological behavior and material extrusion performance of liquid isoprene rubber (LIR) compounds filled with carbon black (CB), silica (Si), and recycled crumb rubber (CR) fillers for potential additive manufacturing applications. The rheological properties of the LIR mixtures were characterized using flow curve analysis and temperature sweeps, identifying shear-thinning behavior and temperature-dependent viscosity ultimately reflecting the final dimensional tolerance of the prints. Vulcanization time (t90) was determined using oscillatory rheometry, and the effect of filler concentration on t90 was evaluated. Mechanical testing was conducted to assess the hardness and tensile properties. The results demonstrate the influence of filler concentration on the rheological properties, printability, and mechanical performance of the LIR compounds thus resulting in the printing of high-strength (σu > 5 MPa) isoprene rubber parts capable of being additively manufactured.

The Effect Of Grain Size To Physico Mechanic Properties Of Particle Board Based On Rice Husk and Liquid Rubber Compound

Particle board research produced from a number of grain size of Rice Husk and liquid rubber compound has been carried out. First particle board was produced by mixing rice husk with a number of grain size were 10-25 mesh; 25-50 mesh; 50-75 mesh and <75 mesh with liquid rubber compound as much as 45% to form a particle board with size of 5 x 10 x 7.5 cm in length, width and height and then dried. Then the particle board is pressed to get a thickness of 2.5 cm and then carried out the characterization of the MOR, MOE, screw pull resistance, water content and density. The results showed that the best rice husk particle size was obtained at 25-50 mesh grain size. At this grain size, the value of MOR, MOE, screw pull resistance, water content, and density of particle board were 9054,8 g/mm2; 15090 g/mm2; 69 g/mm2; 4,1% and 0,83 gr/cm3 respectively. The results of this study still do not meet the standards according to SNI 03-2105-2006

PS/LIR dynamic vulcanization: new approach in TPV development using liquid rubber for impact modification

PS/LIR dynamic vulcanization: new approach in TPV development using liquid rubber for impact modification

Molecular dynamics simulation and experimental analysis on fluidity improvement of liquid rubber modified asphalt binder

Liquid styrene-butadiene rubber (LSBR) has been used as a modifier to improve high-temperature storage stability and cracking resistance of asphalt binder. However, the interaction mechanism between LSBR and asphalt binder at both micro and macro scales has not been well understood. In this study, the intermolecular dynamics, rheological and chemical properties of liquid rubber modified asphalt (LRMA) binder by laboratory experiments and molecular dynamics simulation. Five LSBR dosages (0, 0.5, 1.0, 1.5, 2.0, and 2.5% by weight of asphalt binder) were applied to prepare the LRMA binders. Frequency sweep, performance grading, and multiple stress creep recovery (MSCR) tests were conducted to assess the intermediate- and high-temperatures rheological properties of modified asphalt binders. Fourier transforms infrared (FTIR) spectroscopy was applied to evaluate the chemical properties. Molecular dynamics (MD) simulation was performed to evaluate compatibility and molecular mobility during self-healing process. The results indicated that the addition of LSBR improved the fluidity of asphalt binder at intermediate- and high- temperature, and also enhanced the susceptibility to temperature changes. FTIR results showed that LSBR could effectively delay aging of asphalt binder and ameliorate the service performance degradation. The MD simulation results indicated that the addition of LSBR could improve the solubility of different components in asphalt and the homogeneity of asphalt system. LRMA had a better capability to heal micro-crack than the unmodified asphalt binder. LSBR could improve the fluidity of base asphalt and aged asphalt. It is feasible and appropriate to use liquid styrene-butadiene rubber to improve fluidity of asphalt to meet the requirements of construction and production. Keywords: asphalt fluidity, molecular dynamics simulation, liquid styrene-butadiene rubber, self-healing, rheological property.

Enhancing Surface Temperature Uniformity in a Liquid Silicone Rubber Injection Mold with Conformal Heating Channels.

To enhance the productivity and quality of optical-grade liquid silicone rubber (LSR) and an optical convex lens simultaneously, uniform vulcanization of the molding material is required. However, little has been reported on the uniform vulcanization of LSR in the heated cavity. This paper presents a conformal heating channel to enhance the temperature uniformity of the mold surface in the LSR injection molding. The curing rate of an optical convex lens was numerically investigated using Moldex3D molding simulation software. Two different sets of soft tooling inserts, injection mold inserts with conventional and conformal heating channels, were fabricated to validate the simulation results. The mold surface temperature uniformity was investigated by both numerical simulation and experiment. In particular, both a thermal camera and thermocouples were employed to measure the mold surface temperature after LSR injecting molding. It was found that the uniformity of the mold surface for LSR injection mold with the conformal heating channel was better. The average temperature of the mold surface could be predicted by the heating oil temperature according to the proposed prediction equation. The experimental results showed that the trend of the average temperature of five sensor modes was consistent with the simulation results. The error rate of the simulation results was about 8.31% based on the experimental result for the LSR injection mold with the conformal heating channel.

Gel point investigation of liquid silicone rubber using rheological approaches

Liquid silicone rubber (LSR) is becoming increasingly popular due to its chemical, UV, and heat resistance as well as its excellent optical properties. However, there is currently a lack of research and understanding of the rheological properties of the material. During the processing of liquid silicone rubber, the material can assume different rheological states. In the present work, both the physical and the chemical gel behavior are investigated rheologically. For this purpose, measurements are carried out with a rotational rheometer and a high-pressure capillary rheometer. Depending on the temperature and pre-shear rate, times are given for the physical gel point, after which a significantly destroyed physical network is recovered. Investigations at higher temperatures, which lead to chemical crosslinking and, therefore, to a chemical gel point, resulted in a representation of the temperature-dependent chemical gel point. The presented results serve as a material database for reliable simulations.

Numerical Simulation and Comparison of the Mechanical Behavior of Toughened Epoxy Resin by Different Nanoparticles.

Adding nanoparticles as the second phase to epoxy can achieve a good toughening effect. The aim of this paper is to simulate the toughening behavior of epoxy resin by different nanoparticles using a convenient and effective finite element method. The mechanical behaviors of epoxy resins toughened by nano core-shell polymers, liquid rubber, and nanosilica were compared by numerical simulations using the representative volume element (RVE). It is indicated that the addition of a nano core-shell polymer and liquid rubber can reduce the tensile properties of epoxy resin, while nanosilica is on the contrary. With the increase of nanoparticle content, the length of crack propagation decreases, and the toughening effect of the nano core-shell polymer is the best. The failure mode is determined by the particle/matrix interface when the modulus of the nanoparticle is much larger than that of epoxy resin. However, it is determined by the interface properties of the particle/matrix and the modulus of nanoparticles in other cases. The results provide a theoretical basis for toughening nanoparticle selection of nanoparticle-toughened epoxy resin and other similar simulations in the future.

Al2O3 Nano filler’s impact on electrical, mechanical, thermal, microstructural and the chemical characteristics of liquid silicone rubber for composite insulators

This study examines the function of Al2O3 nanofiller in liquid silicone rubber (LSR) for the purpose of outdoor insulation. Several characteristics, including structural (Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), physical (density), mechanical (tensile, tear, percentage elongation at break, and shore A hardness), thermal (thermal conductivity, thermo gravimetric analysis (TGA)), electrical (dielectric constant, dielectric breakdown strength, DC volume resistivity, arc resistance, and recovery of hydrophobicity), although chemical (immersion of samples for 72 h in NaCl, HCl, and H2SO4 solutions and measurement of sample weight and PH of the solution before and after immersion) were investigated after the addition of Al2O3 nanofiller with different compositions, such as 5, 10, and 15 weight percentages. In comparison to pure LSR, it was discovered that the inclusion of nano Al2O3 particles enhanced the material’s density by 11%, thermal conductivity by 12%, dielectric constant by 24%, DC volume resistivity by 2%, arc resistance by significantly 1205%, dielectric breakdown strength by 54%, and hydrophobicity. Other improvements include a 7% rise in tensile strength, a 23% rise in tear strength, a 17% rise in hardness, and an 18% reduction in percentage elongation at break when compared to pure LSR for the composite samples. Mechanical qualities are affected by the curing process duration. More specifically, we discovered there is a proportionality relationship between the tensile strength and the elastic modulus. Findings of the chemical examination revealed that the composites have corrosion resistance in the form of negligible weight change in the sample when exposed to salt and acid solutions. The combination of these exceptional qualities makes Al2O3 composites appealing within an insulating materials realm.

Facile preparation of smart nanocomposite adhesive with superhydrophobicity and photoluminescence

Smart photoluminescent nanocomposite adhesive was developed toward simple commercial manufacturing of long-persistent luminescent and hydrophobic applications. The prepared photoluminescent glue was able to continue emitting light after turning the illumination source off even after being in the dark for up to 1.5 h. Lanthanide-doped strontium aluminum oxide (LSAO) nanoparticles (NPs) dispersed in liquid silicone rubber (SR) was prepared to function as nanocomposite glue for various surfaces. Using nano-scaled particles, LSAO was uniformly disseminated without agglomeration in the silicone rubber matrix, enabling the produced nanocomposite glue to transmit light. For the applied glues, there is an excitation peak determined at 365 nm, and an emission peak determined at 518 nm. Depending on the LSAO ratio, the photoluminescence spectra displayed either afterglow phosphorescence or fluorescence. Photochromism was monitored from transparent to greenish under UV irradiation and greenish-yellow in darkness. The glued samples benefit from enhanced superhydrophobicity and scratch resistance due to LSAO NPs embedded in the silicone rubber matrix. The glueed LSAO@SR nanocomposite showed high durability and resistance to light damages. This research established the feasibility of mass-producing smart glue for various uses such as building safety directed signs and smart windows.

Particle-reinforced elastomer model to analyse viscoelastic properties of flake-shaped electrolyte iron particle-based magnetorheological elastomer

This paper uses parallel-plate-plate rheometry to focus on the magnetic field-dependent nonlinear viscoelastic behaviour of flake-shaped electrolyte iron powder-based magnetorheological elastomer (MRE). MRE was prepared using liquid silicon rubber as a base, a curing agent and electrolyte iron particles as fillers. Three MRE samples having 60%, 40%, and 0% filler weight fractions were prepared. The curing was carried out at 300 K. The thickness of the sample was 1.00 ± 0.04 mm. Scanning electron microscopy results showed uniform dispersal of particles within a matrix. The swelling measurement technique was used to confirm the enhanced reinforced properties of elastomer by calculating the cross-link density. The magnetic volume fraction evaluated from magnetisation measurements yields values of 18.7% for MRE-60 and 8.7% for MRE-40. Both moduli’s field-induced linear and nonlinear amplitude dependence were analysed using the modified particle-reinforced elastomer model. The result indicates that filler particles adsorbed on polymer chains were essential in determining the reinforcing properties of MRE. The improved cross-link density and particle morphology were responsible for the enhanced field-induced magnetorheological effect (277%). This value is nearly three times greater than that observed in spherical particles-based MRE.

High‐consistency silicone rubber with reduced Young's modulus. An industrial option to dielectric silicone rubber

AbstractFlexible capacitive sensors based on silicone rubber have gained importance in both academic and industrial fields due to their advantages, including low power consumption and high stability to temperature, and humidity. However, pristine silicone rubber has a low dielectric constant (), requiring the use of dielectric additives such as TiO2, BaTiO3, or Sb2O3‐doped SnO2 rutile‐modified particles (ATO) to enhance electrical properties, but they also increase Young's modulus (E). To overcome this problem, liquid silicone rubbers (LSR) are commonly used in academic research due to their low E, but they often compromise mechanical integrity. In contrast, high‐consistency silicone rubbers (HCR), the industry commodity, maintain mechanical integrity even at high filler loadings but are limited in their use in dielectrics due to high E values. This paper explores the potential of vinyl‐terminated HCR for developing dielectric composites with high electromechanical response, with an improved and a reduced E while retaining mechanical and processability properties. The resulting dielectric HCR formulations exhibit optimal properties for developing flexible capacitive sensors using well‐established industrial products and processes.

Natural cardanol modified liquid polyisoprene rubber and its surface adhesion performance

Inspired by mussel protein, the adhesives based on dopamine boom due to its perfect adhesion performance. However, limited by its high price, it is of great significance to study adhesives originated from natural and renewable phenolic and polyphenol compounds which structure is similar to dopamine. The application of natural products can also reduce the consumption of non-renewable petrochemical resources. Herein, the agriculture and forestry by-products cardanol (CA) was grafted onto liquid polyisoprene rubber (LIR) molecular chains to improve its surface energy. Then, the grafting product (LCA) experienced complex formulation (GLCA) and vulcanization (v-LCA). The vulcanization crosslinking was confirmed by the weakening of double bonds absorption in IR spectra and C-C peak in XPS spectra, the enhancement of methyl proton in the α-position of quaternary carbon atom in 1H NMR spectra. The GLCA adhesive agent showed good adhesion performance on wet polar substrates because the drainage effect of LIR and the alkyl chains of CA. Moreover, CA provides the possibility of the multiple interactions as metal bonding, hydrogen bonding, cation-π interaction, π-π stacking, hydrophobic interaction and entanglement between chains. The v-LCA adhesive layer exhibits good solvent resistance. This study provides a prospect of the natural phenolic compounds from agriculture and forestry by-products to be used in the wet adhesion of industry, agriculture, or daily life.

Utilization of liquid epoxidized natural rubber as prepolymer and crosslinker in development of UV-curable palm oil-based alkyd coating

Innovation of new products from renewable resources are important for sustainable development. In this work, novel rubber-integrated palm oil-based alkyd resins were prepared using palm oil, glycerol, diacids, and liquid epoxidized natural rubber (LENR50). The synthesis started with alcoholysis of glycerol by palm oil to produce predominant mixture of monoglycerides, followed by polycondensation with diacids to form alkyd chain. In addition to glycerol, LENR50 was introduced as bio-based polyol for the alkyd synthesis. The rubber prepolymer was chemically integrated into the alkyd chain via the reaction between its epoxide or hydroxyl groups with COOH of diacids during polycondensation. Resultant alkyds were mixed with reactive diluent (styrene), crosslinker (trimethylolpropane triacrylate) and photoinitiators (benzophenone and 1-hydroxycyclohexyl phenyl ketone), and the mixtures were cured under UV irradiation. Introduction of LENR50 into the coating formulation has reduced the curing time, as well as improved some of the film properties of the coatings. Some of the LENR50-based coatings required as short as 3 mins of UV irradiation to form dry-hard films, while the control samples required much longer time. There was also notable increase in the gel content of the LENR-based alkyd coating, suggesting that the polyfunctionality of LENR50 could have increased the extent of crosslinking in the cured film. Other improvement recorded includes pencil hardness, film adhesion, solvent resistance, water resistance, and corrosion resistance. Thermal stability of the alkyd coatings is also reasonably good for general purpose coating applications. The findings from this study suggest that LENR50 could serve as an alternative polyol in synthesis of bio-based polyester binder for surface coating.

The development of composite reinforced hybrid fiber musa acuminata stem-hibiscus tiliaceust bark with filler liquid rubber as vehicle bumper

The characterized of the polyester composites reinforced of the hybrid fiber musa acuminata stem fiber (MASF)-hibiscus tiliaceust bark fiber (HTBF) with liquid rubber filler was studied. The object of research is the polyester composite material, hybrid natural fiber reinforcement and filler Carboxyl Terminated Butadiene Acrylonitryle (CTBN). The polyester composite material which is used as a vehicle bumper, is easily broken and has low heat resistance so that its shape easily changes/shrinks due to heat. This research aims to develop the tensile strength, impact toughness and heat resistance of polyester composites. The reason for using the MASF-HTBF hybrid fiber as a reinforcement for polyester composite materials is because MASF and HTBF are natural fibers that have great potential to be developed to improve the mechanical properties of polyester composites, as substitutes for synthetic fibers. In this study, the conditions of MASF and HTBF were given alkaline treatment by immersing them in 5 % NaOH solution for 24 hours then drying. The combined/hybrid ratio between the MASF and CTBF volume fractions is: 5 %:25 %, 10 %:20 % and 15 %:15 %. To increase impact toughness, CTBN filler is added with variations of 5 %, 10 %. The mechanical characteristics of the specimens were carried out by means of a tensile test and an impact test. The change in mass or shrinkage as a result is tested by TGA. The results showed that the MASF-HTBF hybrid fiber-reinforced polyester composite material with CTBN filler has better mechanical properties than single natural fibers, so it is important to develop it further as a material for making vehicle bumper

Development of an Injection Mold with High Energy Efficiency of Vulcanization for Liquid Silicone Rubber Injection Molding of the Fisheye Optical Lens

Liquid silicone rubber (LSR) techniques are experiencing exponential growth, particularly in the field of high technology due to the low-temperature flexibility, superior heat stability, chemical resistance, and aging resistance of LSR components. Enhancing the curing rate of LSR parts in liquid silicone rubber injection molding is an important research topic. In this study, an injection mold with high energy efficiency of vulcanization for the liquid silicone rubber injection molding of a fisheye lens was developed and implemented. The LSR injection mold has a conformal heating channel (CHC) and conformal cooling channel (CCC) simultaneously. The function of CHC is to enhance the curing rate of a fisheye lens in the LSR injection molding to meet the requirements of sustainable manufacturing. The curing rates of a fisheye lens were numerically examined using the Moldex3D molding simulation software. It was found that the curing rate of the fisheye optical lens cured by injection mold with CHC was better than that of the injection mold with a conventional heating channel. The curing efficiency could be increased by about 19.12% when the heating oil temperature of 180 °C was used to cure the fisheye optical lens. The simulation results showed that the equation y = −0.0026x3 + 1.3483x2 − 232.11x + 13,770 was the most suitable equation for predicting the curing time (y) through the heating oil temperature (x). It was found that the trend of the experimental results was consistent with the simulation results. In addition, the equation y = −0.0656x2 + 1.5827x − 0.894 with the correlation coefficient of 0.9974 was the most suitable equation for predicting the volumetric shrinkage of the fisheye optical lens (y) through the heating oil temperature (x). The volume shrinkage of the fisheye optical lens cured by injection mold with CHC was very similar to that of the injection mold with a conventional heating channel. The maximum volume shrinkage of the fisheye optical lens cured at 180 °C was about 8.5%.

Morphological and rheological investigation of emulsified asphalt/polymer composite based on gray-level co-occurrence matrix

Emulsified asphalt/polymer is one of the most applied composite materials in pavement industry, which is also defined as emulsified polymer modified asphalt (PMA). PMA exhibits the transition behavior of multi-physical states with corresponding viscoelastic characteristics, and studies had focused on the application performances of PMA. However, few had paid proper attention to the morphological compatibility of PMA, which dominated its viscoelastic transition and failure probability directly. This paper aims to establish a gray-level co-occurrence matrix (GLCM) model with morphology theory to quantitatively describe the morphological compatibility of PMA, combined with fluorescent microscope. Furthermore, waterborne polymers with self-crosslinking characteristics are introduced to modify emulsified asphalt, including acrylate, epoxy resin, polyurethane and liquid rubber. The rheological characteristics of PMA are comprehensively evaluated through performance grade, steady shear viscosity, and master curve tests. Finally, a statistical analysis is conducted to establish the relationship between morphological compatibility and rheological characteristics of PMA. The approach introduced in this study could be a promising method to investigate the multi-physical transition behaviors and morphological compatibility of emulsified asphalt/polymer composite material.

Optimized End Functionality of Silane-Terminated Liquid Butadiene Rubber for Silica-Filled Rubber Compounds.

As the world is shifting from internal combustion engine vehicles to electric vehicles in response to environmental pollution, the tire industry has been conducting research on tire performance to meet the requirements of electric vehicles. In this experiment, functionalized liquid butadiene rubber (F-LqBR) with triethoxysilyl groups at both ends was introduced into a silica-filled rubber compound as a substitute for treated distillate aromatic extract (TDAE) oil, and comparative evaluation was conducted according to the number of triethoxysilyl groups. The results showed that F-LqBRs improved silica dispersion in the rubber matrix through the formation of chemical bonds between silanol groups and the base rubber, and reduced rolling resistance by limiting chain end mobility and improving filler-rubber interaction. However, when the number of triethoxysilyl groups in F-LqBR was increased from two to four, self-condensation increased, the reactivity of the silanol groups decreased, and the improvement of properties was reduced. As a result, the optimized end functionality of triethoxysilyl groups for F-LqBR in silica-filled rubber compound was two. The 2-Azo-LqBR with the optimized functionality showed an improvement of 10% in rolling resistance, 16% in snow traction, and 17% in abrasion resistance when 10 phr of TDAE oil was substituted.

Enhancement of tracking resistance of silicone rubber through charge dissipation and radical capture by fluorosilane-grafted iron oxide

Fluorosilane-grafted iron oxide (F-Fe2O3) was prepared via surface grafting reaction between iron oxide and perfluorooctyltriethoxysilane. The effect of F-Fe2O3 on the tracking resistance (TR) of addition-cured liquid silicone rubber (ALSR) was investigated by the inclined-plane test (IPT), surface potential decay test (SPDT), thermogravimetry (TGA), corona aging test and scanning electron microscopy (SEM). F-Fe2O3 delayed the occurrence of the intensive arc discharge and reduced the number of arc discharges. The corona resistance and TR of ALSR were effectively improved. ALSR/F-Fe2O3 with 0.15 phr F-Fe2O3 content passed the IPT at 4.5 kV, showing an erosion mass of 3.17%. The hydrophobicity and thermal stability of ALSR were also enhanced. The SPDT showed that F-Fe2O3 effectively dissipated charge. The results of thermal stability and corona resistance tests revealed that F-Fe2O3 could capture free radicals generated by the oxidation of methyl side groups of ALSR chains and thus inhibit the thermal degradation of ALSR during the arc discharge. Moreover, the charge dissipation by F-Fe2O3 could diminish the accumulation of charges in ALSR and reduce the damage of charges to the chains during arc discharge. Therefore, the TR of ALSR was enhanced.

Enhanced Hydrophobic and Electrical Properties of Silicone Rubber Samples With ZrO2 Nanocomposites

Hydrophobicity is an important property that enhances the insulating performance of polymeric insulators. It further protects the insulator from the formation of the dry band under wet conditions which causes leakage current, flashover, and other surface effects. This work focuses on the enhancement of hydrophobicity by adding ZrO2 nanofillers in different weight percentages (1, 3, and 5 wt%) with liquid silicone rubber (LSR). The diameter of the water droplet is measured by a video measuring system (VMS), and the static contact angle is measured by ImageJ Analysis under clean conditions. As per the American Society for Testing and Materials (ASTM) D2303, the inclined plane test (IPT) is used to determine the tracking and erosion properties of the polymer insulator. IPT results are compared with surface roughness for all the prepared samples. The experimentation reveals that the 5 wt% added nanocomposite sample shows improved hydrophobic and electrical characteristics when compared to all other samples.

Characteristics of 3D Printed Biopolymers for Applications in High-Voltage Electrical Insulation.

Three-dimensional printing technology is constantly developing and has a wide range of applications; one application is electrical insulation, where the standard technology uses polymer-based filaments. Thermosetting materials (epoxy resins, liquid silicone rubbers) are broadly used as electrical insulation in high-voltage products. In power transformers, however, the main solid insulation is based on cellulosic materials (pressboard, crepe paper, wood laminates). There are a vast variety of transformer insulation components that are produced using the wet pulp molding process. This is a labor-intensive, multi-stage process that requires long drying times. In this paper, a new material, microcellulose-doped polymer, and manufacturing concept for transformer insulation components are described. Our research focuses on bio-based polymeric materials with 3D printability functionalities. A number of material formulations were tested and benchmark products were printed. Extensive electrical measurements were performed to compare transformer components manufactured using the traditional process and 3D printed samples. The results are promising but indicate that further research is still required to improve printing quality.