Solid Rubber Research Articles

Successive self-nucleation and Annealing technique applied to polypropylene/butyl rubber composites: Recycling alternatives for vacuum bagging materials

The aerospace sector uses butyl rubber to manufacture carbon fiber components through an autoclave or infusion. Both manufacturing techniques require a high vacuum to achieve adequate impregnation of the carbon fiber fabrics with epoxy resin, and butyl rubber is used as the sealant. The aerospace sector discontinues materials with shelf life expired, and butyl rubber is one of the materials most discontinued for not being used within the designated time. This work presents the development of composites using polypropylene and discontinued butyl tape. Composites with 30, 50, and 70 wt% of butyl rubber content were prepared using a twin-screw extruder. The structural analysis showed that the composites with 50 wt% and 70 wt% are similar to butyl rubber, while the compound with 30 wt% of butyl is similar to polypropylene. The degree of crystallinity of the compound with 50 wt% of butyl content was 18% higher than the PP, and the melting temperature decreased by 30% with the higher butyl content. SSA revealed that the highest enthalpic contribution occurred in the crystalline fraction of higher perfection, except for the compound with 50 wt% of butyl content, whose less perfect crystalline populations grew at the expense of the most perfect crystals. The reduction of the crystalline fraction implies that butyl interferes with the formation of crystals, developing populations with lower lamellar thickness that favors the overall crystallinity of the compound. Young’s modulus, yield strength, and nominal strain decreased with butyl rubber content. The composites showed rough failure surfaces with solid butyl rubber particles and poor adhesion to polypropylene. Butyl particles with diverse sizes and geometries lead to sudden failure of the composites and high dispersion in strain values.

A New Approach to Prevent Injuries Related to Manual Handling of Carts: Correcting Resistive Forces between Floors and Wheels to Evaluate the Maximal Load Capacity

Test methods that use pushing forces to evaluate the maximal load capacities of carts in design standards require a flat, smooth and horizontal steel plate and thus do not take into account the real conditions of work. Resistive forces of a single wheel of a cart in a uniform rectilinear motion were measured using a unique test bench with five loads. Forty-four wheels were tested (varying diameters, treads and bearings) with one steel plate and four resilient floor coverings. Based on a linear mixed model, all the following results were significant (p < 0.05). Resistive forces were increased linearly with the load and depended on the characteristics of both the wheel and floor. These forces decreased as the diameter increased. They were important for wheels with sleeve bearings but decreased for cone ball bearings and precision ball bearings. Resistive forces depended on the material of the tread and were higher for solid rubber treads. In contrast, the hardness of the tread had little effect. Resistive forces strongly depended on the hardness of the base foam of resilient floor coverings: the softer the base foam, the higher the resistive forces. Test methods in design standards should be reviewed, using corrective forces based on these present results, to prevent musculoskeletal disorders.

Research and Application of Temporary Plugging Agent Technology for High-Pressure Wells in Gas Storage Facilities

Before various construction of gas storage well, in order to ensure safety, the reservoir must be temporarily blocked, degassed by circulation and no gas in the well can be operated. There are many temporary plugging methods for oil and gas wells. This paper studies the more advanced micro mesh gel temporary plugging technology in the industry and its application in gas storage wells, which mainly solves the problems of poor degradation backflow effect and difficult permeability recovery caused by weak formation stability after temporary plugging of gas storage wells. Research points: (1) On the basis of ordinary gel, through the fusion with cross-linking agent with special structure, a micron network polymer with significant steric hindrance effect on water molecules is finally formed, which improves the strength and stability of the gel system. (2) Add hexamethylene tetramine, bisphenol propane, delayed cross-linking agent and stabilizer into the polymer aqueous solution. It is verified by laboratory tests that the micron mesh gel can be formed after constant temperature coagulation for 3h~70h at ambient temperature of 90°C~170°C. (3) The temperature resistance, permeability and gel breaking of micron mesh gel are tested in the laboratory, and the results can meet the construction requirements. (4) After the temporary plugging operation of Well Su 49K-2X in the gas storage reservoir of Huabei Oilfield is completed, the degradation products of gel breaking will flow back smoothly to ensure that the well can be put into normal injection and production quickly. The test results show that: (1) Micron mesh gel has the advantages of long plugging validity, high temperature resistance, low viscosity after gel breaking, no residue, thorough gel breaking, no formation plugging pollution, and no impact on the original reservoir permeability. It is a new green plugging technology suitable for deep buried high-temperature depleted oil and gas reservoirs. (2) Before construction, the well temperature shall be measured to conduct test injection, so as to prevent gas invasion from affecting the construction effect. The pump injection displacement is designed to be redundant, so as to prevent the low molecular solution from not reaching the design position in the well on time, and the formation of solid rubber plugs at other positions in the well from affecting the construction.

Recyclable Rubber Flooring in Farrowing Crates and Its Influence on the Development and Welfare of Piglets in the Maternity Phase

To boost productivity in pig production, it is essential to improve the litter size per sow. However, achieving this goal requires reducing newborn mortality rates and increasing their weight gain. In this regard, prioritizing animal welfare and adopting practices that promote sustainability in the activity is crucial. The study aimed to evaluate the sustainable flooring coverage of farrowing crates, considering piglet adaptation, thermal comfort, animal development, and increased productivity. Three types of flooring treatments were defined: T1—wood shavings; T2—solid rubber mat; T3—perforated rubber mat, for 12 litters (±50 animals/treatment). Behavior, physiology, piglet production indices, and facility microclimate were assessed. The facility’s microclimate indicated the possibility of cold stress. There was a greater preference for the mat treatments among the animals, as they remained on them for longer periods and showed increased activity in the farrowing crates. The presence of mats resulted in lower mortality due to crushing, positively contributing to production. These findings suggest the potential of using recyclable rubber mats in pig production and encourage the exploration of new designs and installation locations.

The Impact of Utilizing Waste Tire and Solid Natural Rubber as Asphalt Binder Substitutions on the Asphalt Concrete-Wearing Course Mixtures

The Impact of Utilizing Waste Tire and Solid Natural Rubber as Asphalt Binder Substitutions on the Asphalt Concrete-Wearing Course Mixtures

LATEX AGGLOMERATION AND COAGULATION IN LATICIFERS OF LIVE TARAXACUM KOK-SAGHYZ (RUBBER DANDELION) ROOTS

ABSTRACT The commercialization of Taraxacum kok-saghyz (rubber dandelion) as an alternative rubber crop requires fundamental knowledge of latex, an aqueous suspension of rubber particles, and rubber yield and quality. Rubber particles are formed in the root laticifers from Golgi bodies via the vesicular trafficking system in the cytosol and are then translocated into the vacuoles for storage. However, when freshly harvested roots are processed to extract the latex, much of the latex has already coagulated into solid rubber, reducing the commercial viability of latex extraction from this species. The process of in vivo loss of the latex fraction was investigated histologically, by transmission electron microscopy, in roots of plants grown in soil or hydroponically. In both root types, some rubber particles agglomerated in the cytosol as a precursor to coagulation. Other rubber particles agglomerated and then coagulated after rubber particles were translocated into vacuoles, and also after the cell internal cytoplasmic structure degraded. Uniquely large rubber particles were formed in the vacuoles of hydroponically grown plants by particle coalescence, but were not found in soil-grown roots. Eventually, some root laticifers of both root types filled with solid rubber. The instability of the aqueous latex phase postontogeny through rubber particle agglomeration, coalescence, and coagulation suggests that commercial processes likely would involve root drying to convert residual latex into solid rubber followed by aqueous- or solvent-based extraction.

Effect of fillers on the piezocapacitive behaviour of silicone rubber particulate composites

Robotics and fluid dynamics applications have created demand for development of electronic skins with embedded pressure sensors. These applications require simple and low-cost fabrication processes with large area deployment. Both structured and unstructured material approaches to sensor development have been followed. Among the various sensing mechanisms, piezo capacitive transduction is superior. This paper reports the influence of fillers on the piezo capacitive characteristics of unstructured solid silicone rubber composites. Dielectric, conductive and conductive-dielectric fillers were incorporated into solid silicone rubber and fabricated using high temperature compression moulding to form dielectric-dielectric, conductive-dielectric and conductive-dielectric dielectric composites. The results reveal that piezo capacitive sensitivity varies with filler type, filler loading, curing agent loading, mixing time and curing temperature. The experiments reveal improved normalized capacitance with pressure characteristics of linearity and sensitivity of 3.9 × 10−3 (kPa)−1 in the 0–20 kPa range of pressure. These composites are thus candidate materials for flexible pressure sensing applications.

A novel Foley catheter made of high-intensity near-infrared fluorescent silicone rubber for image-guided surgery of lower rectal cancer

BackgroundUrethral injury occurs in 1–6 % of male cases during minimally invasive surgery of lower rectal cancer. A Foley catheter emitting near-infrared (NIR) fluorescence of sufficient intensity has been expected to locate the urethra during image-guided surgery. Although it has been difficult to impart NIR fluorescent properties to biocompatible thermosetting polymers, we have recently succeeded in developing a NIR fluorescent compound for silicone rubber and a NIR fluorescent Foley catheter (HICARL). Here, we evaluated its NIR fluorescence properties and visibility performance using porcine anorectal isolation specimens. MethodsThe HICARL catheter was made of a mixture of solid silicone rubber and a NIR fluorescent compound that emits fluorescence with a wavelength of 820–880 nm, while a conventional transparent Foley catheter was made of solid silicone rubber only. As a standard for comparison of the intensity of NIR fluorescence, a transparent Foley catheter the lumen of which was filled with a mixture of indocyanine green (ICG) and human plasma was used. As a comparison to assess the visibility performance of the HICARL catheter, a transparent Foley catheter into which a commercially available NIR fluorescent polyurethane ureteral catheter (NIRC) was placed was used. ResultsA NIR fluorescence quantitative imaging analysis revealed that the Foley-NIRC catheter and the HICARL catheter emitted 3.42 ± 0.42 and 6.43 ± 0.07 times more fluorescence than the Foley-ICG catheter, respectively. The location of the HICARL catheter placed in the anorectum with a wall thickness of 3.8 ± 0.1 mm was clearly delineated in its entirety by NIR fluorescence, while that of the Foley-NIRC catheter was faintly or only partially visible. ConclusionsThe HICARL catheter emitting NIR fluorescence of sufficient intensity is a promising and easy-to-use tool for urethral visualization during image-guided surgery of lower rectal cancer.

Solid Rubber Fenders to Prevent Structural Damage in a Lowspeed Collision Between a Ship-Shaped Offshore Installation and a Shuttle Tanker Working Side-by-Side in Offloading Operation

Ships and ship-shaped offshore installations are commonly equipped with pneumatic or solid rubber fenders to absorb kinetic energy during collisions, thereby reducing structural damage. The energy absorption capacity of these fenders must be precisely evaluated via reliable experimental, analytical, and numerical methods to ensure that the fenders are capable of preventing collision-associated structural failures. Accordingly, this study developed computational modelling techniques for analysing the energy absorption capacity of solid rubber fenders. Modelling was performed using LS-DYNA, a commercial software package for finite element simulation, and the developed models were validated by comparison with data from crushing tests on two types of solid rubber fender models – circular tube and V-shaped rubber fenders. The validated computational models were applied to examine a case study of a low-speed collision between a Suezmax class shuttle tanker and a very-large-crude-oil-carrier (VLCC) class ship-shaped offshore installation working side-by-side in offloading operation, with the latter equipped or not equipped with V-shaped rubber fenders, respectively. The results revealed that such fenders were effective protection against structural damage in such a collision scenario.

Innovation in natural rubber latex coagulation using CO2 microbubbles

Traditionally, acids have been employed in the production of raw rubber sheets. Using concentrated acids to coagulate natural rubber latex has led to issues such as subpar product quality and the generation of a significant volume of acidic latex serum waste. In contrast, opting for weak acids results in increased production costs. To address these limitations, this research adopts an innovative approach that leverages CO2 microbubbles as a process intensification technique. CO2 was bubbling into a bubble column filled with fresh natural rubber latex and closely monitored the pH and coagulation percentage over time. The physical and mechanical properties of the solid rubber products were characterized, in comparison with the products gained from conventional techniques. The use of CO2 microbubbles yielded shorter processing times and reduced the generation of acidic waste serum. Notably, this approach also led to significant improvements in key properties such as initial Wallace plasticity (P0), plasticity retention index (PRI), nitrogen content, and biodegradability in soil of the rubber samples. Interestingly, the utilization of CO2 as a feedstock highlights its role in promoting a sustainable process. This innovative approach not only minimizes environmental impact but also results in the production of value-added rubber products with enhanced properties.

Rheological Characteristics of Asphalt with a Crumb Rubber and Solid Natural Rubber Combination

Rheological Characteristics of Asphalt with a Crumb Rubber and Solid Natural Rubber Combination

Thermo-mechanical behavior of solid rubber tire under high-speed free rolling conditions

Thermo-mechanical behavior of solid rubber tire under high-speed free rolling conditions

Peroxide‐based crosslinking of solid silicone rubber, part II: The counter‐intuitive influence of dicumylperoxide concentration on crosslink effectiveness and related network structure

AbstractApplication of elastomers in general demands the conversion of their soluble networks into crosslinked structures. This abrupt change causes several modifications, both in the atomic/molecular level and at the macro‐scale. In this study, solid silicone rubber (high molecular weight poly(dimethylsiloxane)), was crosslinked with dicumylperoxide (DCP), a widely used crosslinking agent by the rubber industry. The changes caused by different DCP concentrations were investigated, aiming to bring attention to the molecular transformations, usually neglected when processing‐oriented studies are conducted. DCP concentration showed a limited contribution to the network's molecular dynamics, which was found to be mainly dominated by entanglements. The dominance of entanglements over other molecular constraints, like crosslink points, justifies the threshold and counter‐intuitive behavior of tensile and hardness properties. However, differences were found in the crystallization ability after crosslinking, when the more crosslink points were introduced, the lower the crystallinity was and the less stable the PDMS crystallites were. In addition to providing a deeper understanding of an industrially applied rubber system n terms of the effective concentration of DCP, and the reasoning behind such concentration, the findings of this study add to the state‐of‐the‐art comprehension of elastomeric networks, and how they behave on a molecular level.

Fourier spectral theory of pulsed photothermal radiometry, signal analysis, and parametric measurements in two-layered media

A theoretical model of pulsed photothermal radiometry based on conduction-radiation theory is introduced for a two-layered medium with a first layer having optical and thermal properties different from those of the semi-infinite substrate. This geometry closely represents the optical and thermal properties of biotissues, a major intended application. The theory derives the spatial distribution of the frequency spectrum of the pulsed photothermal signal from the composite two-layer boundary-value problem and matches the spectral frequency domain results to the measured photothermal transients through an efficient inverse Fourier transformation algorithm, which involves the optical, thermal, and geometric parameters of the experimental system. This approach avoids the complicated and computationally expensive analytical Laplace transform approach usually adopted in similar studies and yields a complete conduction–radiation description of photothermal signals without simplifying, yet restrictive, approximations encountered in the literature. Numerical and experimental tests of the model using intralipid solution as layer 1 and semi-infinite solid samples such black rubber and anodized aluminum as layer 2 of the medium are described. The radiation heat transfer coefficients from the air–intralipid and intralipid–solid interfaces were introduced to complement the conductive blackbody-radiated infrared signal component at the detecting camera. The best-fitted parameters and heat transfer coefficients are compared to theoretical and experimental data, and the results of these tests were found to be consistent with the theoretical model.

The implementation of an easy-to-apply NMR cryoporometric instrument for porous materials

Time-domain NMR has been extensively utilised to study various characteristics of fluid-saturated porous,materials for instance their mobility, dynamics, stiffness, viscosity and rigidity features, particularly for solid hydrocarbons, rubbers and other polymers. As a unique time-domain technique available for over 30 years, NMR cryoporometry (NMRC) may be used to obtain pore-size distributions of the measured samples. To accurately control the sample temperature, a Peltier thermo-electrically cooled variable temperature probe has been developed and integrated with a highly compact precision NMR time-domain relaxation spectrometer, therefore providing the community with a high-performance instrument for NMR Cryoporometry. To extend the application of aforementioned high-performance NMRC instrument into more senarios, we designed a series of light-weight, compact and integral models with optional NMR frequencies from 12 MHz up to 23 MHz. The measured sample temperature can be precisely controlled from about −60 °C to +80 °C, with an excellent temperature resolution of 10 mK or better near the probe liquid bulk melting point. Therefore, it offers a fairly wide NMRC pore-size distribution ranging from about 1 nm to 2 μm by using water as the probe liquid in the pores, significantly wider than is possible when applying generic NMR Spectrometers for NMRC. A preliminary example of NMR Cryoporometric measurements on two special cement samples is shown in the paper in which the measured pore scales as well as their repeatability are demonstrated. Furthermore, various nano-materials, such as MOF, zeolite and shale kerogen would be potential materials to study by using these new available NMRC instrument models. We aim to offer this technique as a quantitative and easy-to-apply unitary benck-top tool for an even wider range of porous material.

Characterization of Natural Rubber, Styrene Butadiene Rubber, and Nitrile Butadiene Rubber Monomer Blend Composites Loaded with Zinc Stearate to Be Used in the Solid Tire Industry

Vulcanization is an important step in the manufacture of solid tires in which the crosslinking process occurs. In vulcanization, the materials commonly used as activators and coactivators are ZnO and stearic acid, respectively. In this research, ZnO and stearic acid were replaced with zinc stearate to improve the characteristics of vulcanized rubber. Zinc stearate was applied in four formulas with a composition of 5 to 9 phr. A formula that is often used in the rubber industry was used as a comparison, and ZnO and stearic acid of 5 phr and 2.5 phr, respectively, were applied. The rubber compound for solid tire production was developed using an open mill at a compounding temperature of 45 °C ± 5 °C. The vulcanization process of developing the rubber compound into vulcanized rubber was carried out at 150 °C for 20 min. Rubber compound test results showed that the use of zinc stearate at a ratio of 8 phr accelerated the curing time (t90) between 58.3% and 69%, the scorch time (ts2) between 22.4% and 95.5%, and the torque delta (Δs) between 17.67 and 24.21 kg-cm. In addition, the vulcanized rubber mechanical properties test results for the compression set parameter increased between 28.6% and 57.1%. Scan results with SEM–EDS showed that using ZS could improve the homogeneous distribution of the material in the vulcanized matrix of solid tire rubber.

High temperature resistant rubber asphalt

Rubber Asphalt is the asphalt with rubber addition. The addition of rubber to asphalt was expected to have higher stiffness and longer durability that can be identified by its properties, that are softening point, penetration and ductility. The 60/70 penetration asphalt has been mixed with 7% rubber. Mixing of rubber with asphalt was quite a challenge. The liquid rubber or solid rubber should be processed through prevulcanization in the asphalt plant. The properties of the rubber asphalt have been investigated in the laboratory of BPJN West Sumatera. Hence, the properties of rubber asphalt have followed the Bina Marga standard for pavement mixture, i.e. the softening point value is >52°C, the ductility is more than 140 cm, and the burning point was above the 310°C. By determined the index penetration of the rubber asphalt that is. Thus, it can be concluded that the 7% rubber asphalt has resulted in the higher resistance to higher temperature binder.

Thermo-mechanical-abrasive coupling analysis of solid rubber tire under high-speed rolling

High friction and large deformation under high-speed sideslip landing conditions cause rapid heating and severe abrasion of aircraft tire, which seriously threatens landing safety. Therefore, theories of energy dissipation and transient heat transfer are discussed. A thermo-mechanical-abrasive (TMA) coupling analysis method is proposed for solving the thermomechanical problem. Laws of temperature and abrasion under different slip angles are revealed experimentally. Results show that sideslip conditions lead to increase of friction energy dissipation and wear as well as an asymmetric distribution of temperature field; Considering abrasion can effectively improve prediction accuracy of thermomechanical analysis (an increase of 27.65%), the predicted temperature and abrasion profile are in good agreement with the experiment data.

Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach.

Predicting the curing behaviour of industrially employed elastomeric compounds under typical processing conditions in a reliable and scientifically driven way is important for rubber processing simulation routines, such as injection moulding. Herein, a rubber process analyser was employed to study the crosslinking kinetics of solid silicone rubber based on the concentration of dicumylperoxide. A model was proposed to describe the optimal cure time variation with peroxide concentration and temperature, based on the analysis of processing parameters applying kinetic and thermodynamic judgments. Additionally, the conversion rate was described with the aid of a phenomenological model, and the effect of dicumylperoxide concentration on the final crosslink state was investigated using kinetic and thermodynamic explanations. Optimal curing time was affected both by temperature and dicumylperoxide concentration. However, the effects were less pronounced for high temperatures (>170 C) and high concentrations (>0.70 phr). A limit on the crosslink state was detected, meaning that the dicumylperoxide capacity to crosslink the silicone network is restricted by the curing mechanism. Curing restrictions were presumed to be primarily thermodynamic, based on the proton abstraction mechanism that drives the crosslinking reaction. In addition to providing more realistic crosslinking models for rubber injection moulding simulation routines, the results of this study may also explain the chemical behaviour of organic peroxides widely used for silicone crosslinking.

Geometrical Parameters Optimization of Malaysia Rubber Wood through Honeycomb Structure as Composite Sandwich Core

Rubber wood has multiple functions especially in the furniture industry and other wood products such as plywood whereas the sawdust is further processed to become medium density fiberboard or wood plastic composites. These composites are useful yet are unable to become the structural components where mechanical performance is critical. An investigation was carried out to find out the mechanical properties of rubber wood honeycomb core in the fiber reinforced composites with glass fiber as its facesheet and epoxy as its matrix. Cell diameter fabricated at 7 mm with increasing cell wall thicknesses ranging from 1 mm to 3 mm respectively. In the flatwise tensile test, the results showed that the interfacial bonding strength increased by 21.6% with increasing wall thickness. As higher density increased and minimum strength improvement, the specific strength will be reduced. Meanwhile, wall thickness of 3 mm is only 1% away from the sandwich composite with solid rubber wood which has the most similar bonding strength as in climbing drum peel test with lower density.