Rubber Films Research Articles

Transparent flexible fluorescent films based on natural rubber composited with quantum dots for traffic equipment

Quantum dots are one of the nanotechnology materials applied in various ways like flexible electronic devices and others. In this work, we study and synthesize semiconductor quantum dots (SQDs) to produce fluorescent natural rubber films by the technique called directed blending. We illustrate the appropriate ratio of mixtures employed in our method such as quantum dot colloidal solutions and natural latex as well as moles between each substance. During the process, the liquid composite and rubber adhesive is applied to the surface for creating flexible fluorescent films that can be dried at room temperature. In addition, these flexible fluorescent films can be covered with diverse curved surfaces applied probably as a traffic device like luminous traffic cones or traffic signs that glow at night. Based on the unique properties of our products, our research provides an application developed from quantum dot nanotechnology.

Inhibition of Adherence and Biofilm Formation of Pseudomonas aeruginosa by Immobilized ZnO Nanoparticles on Silicone Urinary Catheter Grafted by Gamma Irradiation.

Nosocomial infections caused by microbial biofilm formation on biomaterial surfaces such as urinary catheters are complicated by antibiotic resistance, representing a common problem in hospitalized patients. Therefore, we aimed to modify silicone catheters to resist microbial adherence and biofilm formation by the tested microorganisms. This study used a simple direct method to graft poly-acrylic acid onto silicone rubber films using gamma irradiation to endow the silicone surface with hydrophilic carboxylic acid functional groups. This modification allowed the silicone to immobilize ZnO nanoparticles (ZnO NPs) as an anti-biofilm. The modified silicone films were characterized by FT-IR, SEM, and TGA. The anti-adherence ability of the modified silicone films was evidenced by the inhibition of biofilm formation by otherwise strong biofilm-producing Gram-positive, Gram-negative, and yeast clinical isolates. The modified ZnO NPs grafted silicone showed good cytocompatibility with the human epithelial cell line. Moreover, studying the molecular basis of the inhibitory effect of the modified silicone surface on biofilm-associated genes in a selected Pseudomonas aeruginosa isolate showed that anti-adherence activity might be due to the significant downregulation of the expression of lasR, lasI, and lecB genes by 2, 2, and 3.3-fold, respectively. In conclusion, the modified silicone catheters were low-cost, offering broad-spectrum anti-biofilm activity with possible future applications in hospital settings.

Developing ternary composite phase change materials with two different phase change temperatures for battery thermal management

Paraffin wax (PW), as a phase change material (PCM), with high latent heat, is likely to be used in battery thermal management. However, the application of PW is remarkably limited due to its low thermal conductivity, poor mechanical properties, and easy leakage after melting. Here, we prepared a novel ternary composite phase change material (CPCM) to eliminate melt leakage with high thermal conductivity, stable morphology, and two different phase change temperatures. The step cooling data confirmed that when the proportions of myristic acid (MA), palmitic acid (PA), and PW are 3:1:4, there are two phase transition points at 35.88 ℃ and 46.26 ℃, respectively. The addition of short carbon fiber (SCF) and carbon black (CB) with different particle sizes significantly improved the thermal conductivity of the PCM up to 8.7 W/mK. The addition of silicone rubber (SR) film not only avoids the liquid PCM leakage but also improves its mechanical properties. At the highest discharge rate, the maximum temperature of a large capacity square terpolymer lithium battery is 47.03 ℃ due to excellent thermos conductivity. Furthermore, the ternary CPCM does not melt completely at the end of discharge. Compared with the CPCM with single phase transition temperature, the two different phase transition temperatures have excellent balanced performance. After two phase change temperature controlling processes, the rise of battery surface temperature is effectively delayed, and the working time of the CPCM is prolonged. Hence, the developed CPCM is more suitable for the battery thermal management system (BTMS).

CuO/Ag hybrid nanomaterial coated hydrophilic natural rubber film with minimal bacterial adhesion and contact killing efficiency

The formation of biofilms and bacterial infections associated with biomedical equipment continues to be a severe clinical problem. To provide a high-efficiency bactericidal coating, CuO/Ag hybrid nanomaterial was introduced onto the surface of natural rubber polymer by a simple immersion strategy. The hybrid nanomaterial was synthesised using Carboxymethyl chitosan as the stabilising agent. The effective conjugation of CuO/Ag on rubber film was assured by inductively coupled plasma mass spectrometry (ICP-MS) and hydrophilicity of the coated and uncoated rubber films were tested by water contact angle measurements. The antimicrobial drop test results authenticate the eradication of the attached bacterial strains. The live/dead bacterial assay further confirmed the destruction of 83% of E. coli and 92% of S. aureus on the rubber film with minimal bacterial adhesion. In fact, clinical infections caused by biofilms are more challenging in the healthcare sector rather than those caused by planktonic cells. The colorimetric (crystal violet) assay depicts that there is biofilm reduction of 53.82% E. coli, 54.87% S. aureus and 49.71% P. aeruginosa on rubber film by modification with CuO/Ag. The results of qualitative and quantitative antibacterial assessments show good bacterial resistance for the coated rubber film. The modified hydrophilic surface can be selectively used in rubber-based medical devices, especially to avoid nosocomial infections.

Impact of N,N ′ -Methylene-bis-Morpholine on the Preservation of Natural Rubber Latex

Natural rubber latex (NRL) preserved by high ammonia (HA) presents substantial pollution issues despite its good all-around properties. Cleaning preservation of NRL is critical in the modern rubber industry. In this study, NRL was preserved using N,N ′ -methylene-bis-morpholine (MBM), and the impact of MBM on the preservation and characteristics of NRL was investigated. The results showed that when the MBM dose was greater than 0.15 wt%, the volatile fatty acid value (VFA No.) and viscosity value of fresh NRL were lower, and it could be stored for longer than 5 days without losing stability. Furthermore, MBM demonstrated a favorable preservation effect on concentrated NRL (CNRL). To be effective, MBM must be administered at a dosage greater than 0.3 wt%. The mechanical stability test (MST) and VFA No. of the low-ammonia (LA)-CNRL prepared by MBM combined with ammonia were somewhat lower, whereas the viscosity value was greater. The research showed that the dose of lauric acid soap needs to be increased to improve the stability of ultra-LA-CNRL made by MBM–ammonia composite preservation. After pre-vulcanization treatment, the stability of LA-CNRL preserved by MBM–ammonia composite was drastically reduced. As the stabilizer dose was increased, the CNRL viscosity value decreased, whereas the MST and heat stability improved. The LA-CNRL vulcanized film has excellent mechanical properties similar to HA-CNRL. Furthermore, the infrared spectrum of the LA-CNRL raw rubber film was similar to that of the HA-CNRL film. The thermal degradation curve and characteristic temperature were also similar to that of the HA film. The study indicates that MBM has an outstanding preservation effect on fresh NRL and LA-CNRL, and the findings constitute a significant step forward in the development of the CNRL sector.

A novel preparation of natural rubber films with a conducting nanocarbon network for antistatic applications

A novel preparation of natural rubber films with a conducting nanocarbon network for antistatic applications

The Effect of Pre-Stretched Substrate on the Electrical Resistance of Printed Ag Nanowires.

One-dimensional nanomaterials have drawn attention as an alternative electrode material for stretchable electronics. In particular, silver nanowires (Ag NWs) have been studied as stretchable electrodes for strain sensors, 3D electronics, and freeform-shaped electronic circuits. In this study, Ag NWs ink was printed on the pre-stretched silicone rubber film up to 40% in length using a drop-on-demand dispenser. After printing, silicone rubber film was released and stretched up to 20% as a cyclic test with 10-time repetition, and the ratios of the resistance of the stretched state to that of the released state (Rstretched/Rreleased) were measured at each cycle. For Ag NWs electrode printed on the pre-stretched silicone rubber at 30%, Rstretched/Rreleased at 10% and 20% strain was 1.05, and 1.57, respectively, which is significantly less than about 7 for Ag NWs at the 10% strain without pre-stretched substrate. In the case of 10% strain on the 30% pre-stretched substrate, the substrate is stretched and the contact points with Ag NWs were not changed much as the silicone rubber film stretched, which meant that Ag NWs may slide between other Ag NWs. Ag NWs electrode on the 40% pre-stretched substrate was stretched, strain was concentrated on the Ag NWs electrode and failure of electrode occurred, because cracks occurred at the surface of silicone rubber film when it was pre-stretched to 40%. We confirmed that printed Ag NWs on the pre-stretched film showed more contact points and less electric resistance compared to printed Ag NWs on the film without pre-stretching.

Multifunctional Cellulosic Natural Rubber and Silver Nanoparticle Films with Superior Chemical Resistance and Antibacterial Properties.

Composite films of natural rubber/cellulose fiber/silver nanoparticle were synthesized in a green route via the latex solution process. Hybrid cellulose filler containing carboxymethyl cellulose and cellulose microfibers was used to facilitate facile and fast preparation and to improve mechanical strength to the composites, respectively. All the composites possessed a high tensile strength of ~120 MPa, a high heat resistance of nearly 300 °C, and more than 20% biodegradability in soil in two weeks. Chemical resistance and antibacterial activity of the composite was enhanced depending on sizes and concentrations of silver nanoparticles (AgNPs). The composites containing 0.033-0.1% w/w AgNPs retarded toluene uptake to less than 12% throughout 8 h, whereas the composite containing 0.067-0.1% w/w AgNPs exhibited excellent antibacterial activities against Escherichia coli and Staphylococcus aureus. In comparison, 50 nm-AgNPs presented higher antibacterial activities than 100 nm-AgNPs. In vitro cytotoxicity test assessed after incubation for 24 h and 48 h revealed that almost all AgNPs-composite films exhibited non/weak and moderate cytotoxicity, respectively, to HaCaT keratinocyte cells.

Ti3C2/Ni2P/triphenyl phosphite as antioxidative microwave absorbers with excellent photothermal property

Microwave absorbers with the high-efficiency photothermal conversion performance are currently lacking but significantly desired as they can provide a sufficient heat energy besides the absorption property. Herein, Ti3C2/Ni2P/triphenyl phosphite (TPOP-Ti3C2/Ni2P) composite was synthesized by an ingenious one-pot solution-phase reaction and proved to be a superior antioxidative microwave absorbent with excellent photothermal properties. Ni2P can effectively optimize the impedance match of Ti3C2 MXene and consequently improve its microwave absorption (MA) performance. Results show that the minimum reflection loss value of TPOP-Ti3C2/Ni2P is −57.87 dB at 10.88 GHz, the maximum effective absorption bandwidth is 5.04 GHz, and the thickness is merely 1.8 mm. Notably, TPOP on the MXene surface can serve simultaneously as an antioxidative stabilizer and a capping agent to improve its hydrophobicity and chemical stability. The average water contact angle of TPOP-Ti3C2/Ni2P is prompted to 96.59°, while the average oil contact angle is 26.02°. Moreover, compared with the pure Ti3C2, TPOP-Ti3C2/Ni2P has an obvious antioxidant stability in aqueous solution. Additionally, Ni2P nanoparticles exhibit a dipole resonance mode under illumination conditions, which enhances the surface absorption capability of visible light. The surface temperature of the natural rubber film after introducing TPOP-Ti3C2/Ni2P increased rapidly under simulated light, showing a high photothermal conversion ability. Furthermore, the MA performance of the composite film remains basically unchanged, whether is repeatedly bent or exposed under a harsh sun. This study provides a new strategy for manufacturing MA materials with efficient photothermal properties for the possible application to design wearable devices that can combine electromagnetic protection and self-generated heat.

Higher Adhesion Strength Over 10 N/mm Between Rubber and Fluoropolymer Film When Treated by Atmospheric Plasma-Graft Polymerization

An evaluation of the adhesion between rubber and fluoropolymer films treated by atmospheric plasma-graft polymerization is conducted to realize a low-permeation fuel rubber hose covered with fluoropolymer. The low-permeation fuel rubber hose is important for reducing vehicular evaporative emissions. Although fluoropolymers have extremely low permeability for fuel, it is difficult to bond them with other materials, such as rubber, because of their low adhesive properties. Plasma surface modification has been investigated to improve the adhesive properties of fluoropolymers. However, it is difficult to realize effective and permanent surface treatment using plasma alone. Based on the new and effective combined plasma surface-modification technique for fluoropolymer films, we previously proposed an atmospheric-pressure plasma method followed by graft polymerization of hydrophilic monomers such as acrylic acid (CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = CHCOOH). In this study, three types of rubber, isobutylene isoprene rubber (IIR), ethylene acrylic elastomer (AEM), as well as white-colored ethylene acrylic elastomer (white AEM), and two types of fluoropolymer films, denatured PFA-1 and denatured PFA-2, were prepared. The treated fluoropolymer film and rubber were adhered using vulcanized adhesion, and then the 180° peeling strength test was conducted. The results show that an average peeling strength of 12.6 N/mm and a maximum peeling strength of 15.3 N/mm, which are over 10 N/mm, are attained for the sample of vulcanized bonding of the treated denatured PFA-1 and AEM.

Releasing of zinc ions from modified zinc oxide surfaces for improvement chemical crosslinks and antibacterial properties of acrylonitrile butadiene rubber films

Releasing of zinc ions from modified zinc oxide surfaces for improvement chemical crosslinks and antibacterial properties of acrylonitrile butadiene rubber films

Fingerprint-inspired surface texture for the enhanced tip pinch performance of a soft robotic hand in lubricated conditions

The core capabilities of soft grippers/soft robotic hands are grasping and manipulation. At present, most related research often improves the grasping and manipulation performance by structural design. When soft grippers rely on compressive force and friction to achieve grasping, the influence of the surface microstructure is also significant. Three types of fingerprint-inspired textures with relatively regular patterns were prepared on a silicone rubber surface via mold casting by imitating the three basic shapes of fingerprint patterns (i.e., whorls, loops, and arches). Tribological experiments and tip pinch tests were performed using fingerprint-like silicone rubber films rubbing against glass in dry and lubricated conditions to examine their performance. In addition to the textured surface, a smooth silicone rubber surface was used as a control. The results indicated that the coefficient of friction (COF) of the smooth surface was much higher than that of films with fingerprint-like textures in dry and water-lubricated conditions. The surface with fingerprint-inspired textures achieved a higher COF in oil-lubricated conditions. Adding the fingerprint-like films to the soft robotic fingers improved the tip pinch gripping performance of the soft robotic hand in lubricated conditions. This study demonstrated that the surface texture design provided an effective method for regulating the grasping capability of humanoid robotic hands.

Sulfonated, quaternized, and chlorogenic acid composited sodium alginate hydrogels/Eucommia ulmoides rubber films as in vitro antibacterial wound dressings for accelerating wound healing

It is important to improve antibacterial properties and maintain desirable humidity of wound dressings. Herein, novel antibacterial wound dressings were prepared. Sulfonated SA, quaternized SA, and chlorogenic acid composited SA hydrogels were used and coated on Eucommia ulmoides rubber (EUR) films. These hydrogels were characterized by FTIR, SEM, zeta potential, swelling behavior and rheology. Moreover, the biocompatibility of the hydrogels was studied by fibroblast cells (L929). Then, the mechanical property and water vapor permeability of wound dressings were tested. Meanwhile, the drug release behavior of the wound dressings was determined by the Korsmeyer-Peppas model and their antibacterial effects on E. coli and S. aureus were studied. Finally, wound healing performance was evaluated by mouse full-thickness wounds model. After 11 days, the wound healing rates in the treatment groups can reach more than 90%, in particular, CGA-SA/EUR group had the highest healing rate of 98%. The results from histopathological observation and immunohistochemical staining showed these wound dressings could effectively promote the wound regeneration and repairing, indicating the wound dressings can be potentially used for accelerating wound healing.

Modeling the influence of rheology on smooth rod coating systems

Rod coating methods are of interest for the application of barrier coatings, especially at off-line facilities that may run at moderate speeds and narrow web widths. At lower line speeds and lower coating solids, it is difficult to achieve good coat weight control because of poor loading of the rod. While there is extensive literature available about blade and roll coating, there seems to be less reported on the rod loading of smooth rods to obtain various coat weights. Much of the work is around metering rods working on applicator rolls at high speeds that are associated with the metered size press, with a focus on ribbing instabilities. This work employs a simplified model, neglecting some complex features of rubber deformation and film split, to estimate the influence of the process parameters such as speed, rod diameter, viscosity, and rod loading on the coat weight obtained. As found in practice, at low speed and low viscosities, the coat weight-load curve is steep, leading to poor control of the coat weight and coat weight uniformity. If the viscosity is increased, the curve is modified, and control is possible with rod loading in a normal range. For shear thinning fluids described by the Carreau model, the power law index and other parameters need to be in the correct range to obtain the desired effect. Modeling predictions show a steeper dependence of coat weight with rod pressure when compared to pilot coater data. This may be caused by missing details in the mechanical loading of the rod related to tube pressure or from neglecting the impact of filter cake formation of the applied coating in the model.

Study of Dynamic Evolution of the Shear Band in Triaxial Soil Samples Using Photogrammetry Technology

In order to avoid the influence of end restraint on triaxial stress and strain measurements, this study combines photogrammetry and computer technology to apply to the unconsolidated undrained test of triaxial soil samples. The novel method can establish an intuitive shear band evolution model of soil samples and help attain a clear and intuitive shear band evolution law. On the basis of the conventional triaxial test, this new method needs to paste the RAD (Ringed Automatically Detected) code points on the rubber film, plexiglass cover and brackets and then take pictures of the RAD code points in the loading process in a surrounding manner, with which the 3D shape of the restored soil samples can be determined. After eliminating the influence of refraction, the coded point cloud coordinates measured in the experiment can be used to calculate the axial deformation and radial deformation of the soil sample in the deformation process and determine the local stress–strain curve and three-dimensional displacement field diagram of the soil sample. The test shows that the new method can clearly determine the peak value and inflection point of the stress–strain curve in the middle region of soil samples, enabling it to reflect the shear change process of the soil sample more accurately. In addition, the displacement field can be used to directly observe the formation, development and penetration process of the shear band in soil samples.

Preparation and Characterization of Porous Natural Rubber Loaded with Silver Nanoparticles

In this study, porous natural rubber (NR) films loaded with silver nanoparticles (AgNPs) were prepared by the solvent casting method. The porous structure of the NR films was formed with hydrophilic substances such as glycerol, pectin or carrageenan. The film properties including morphology, mechanical test, hydrophilicity evaluation, water absorption, release study, and antibacterial activity were determined. From the results, the morphology of films was a continuous porous structure on the surface of films. The pectin and carrageenan enhanced porosity, hydrophilicity, and water sorption of the porous NR films. The developed porous NR films could sustain the release of Ag+ ions for 2 days and showed inhibition zones against Staphylococcus aureus and Escherichia coli. Therefore, these porous NR films have the potential to be used as chronic wound dressing.

Preparation of high‐performance deproteinized natural rubber/chitosan composite films via a green and sulfur‐free method

AbstractTo solve the environment and health issues arose from the sulfur vulcanization, a facile and completely eco‐friendly method of latex‐assembly and in situ cross‐linking is developed to prepare fully bio‐based and high‐performance rubber films. The films are featured by a “reinforced concrete” structure composed of dynamically cross‐linked chitosan framework and unvulcanized deproteinized natural rubber (DPNR) matrix. The self‐assembly of DPNR latex particles and chitosan, as well as the in situ cross‐linking of chitosan in the film forming process are confirmed by transmission electron microscope and dynamic light scattering. As green rubbers without vulcanization, the as‐designed composite films possess excellent mechanic properties comparable to those of the sulfur vulcanized DPNR film, whose tensile strength and toughness reach 15.2 MPa and 77.6 MJ m−3 respectively. Moreover, the films exhibited appropriate permeability to moisture and achievable reprocessing, which have potential applications in wearable devices.

Thermal and photo oxidative degradation of natural rubber film in the presence of iron (III) stearate

Thermal and photo oxidative degradation of natural rubber film in the presence of iron (III) stearate

(Invited) Stretchable Sensing Devices Combining Ionic Liquids and Soft Electrodes

In recent years, a variety of ultra-flexible devices have been proposed. Their applications include wearable devices and soft robots. Among ultra-flexible devices, the devices with stretchablity is attracting attention as next-generation sensing devices. In such devices, ionic liquids can be used as a sensing material. Ionic liquids are polymers in a liquid state and their structure can be easily altered, For example, ionic liquids can be developed reactive to temperature, humidity, light, gases, and many other factors. Furthermore, since they are in a liquid state, they are durable against device stretching. In this study, we report on a stretchable sensing device using ionic liquids. In particular, by using liquid metal and CNT(Carbon nanotube) as electrode materials, we propose a super-stretchable device and a super-flexible device with transparency and high breathability.<Temperature/humidity/oxygen/optical sensors using liquid metal electrodes> liquid metal was used as electrode, and ionic liquids as a sensing material. Equivalent circuit of the sensors were established based on Nyquist plot The sensor showed stable sensitivity to temperature without hysteresis as shown with a 0.039/°C increase in conductivity, which is quite high compared to other reports. We also show proof of concept for humidity, oxygen gas, and optical sensings using four kinds of ionic liquids, 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][Otf]), 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMPYR][NTf2]) and 1-butyl-3-(4-phenylazobenzyl)imidazolium bis(trifluoromethanesulfonyl)amide ([Azo][NTf2]) for optical sensing. The sensitivity of each ionic liquid to humidity and oxygen differed depending on the ionic liquid. For each type of stimuli, the sensing can be optimized by choosing the proper ionic liquid. In addition, using [Azo][NTf2], we demonstrate optical sensing and memory in this study.< Transparent and Breathable Ion Gel-based Sensors using CNT> highly transparent, ultra-flexible, and gas-permeable polymer thin-film sensors using ion gels as the sensing material, which demonstrated the capacity for selective detections, were proposed. Particularly, simultaneous and independent sensing of temperature and humidity was demonstrated in this study. The sensors were fabricated using a simple spray coating method on a thin silicone rubber film (around 25 µm thickness). Owing to their thin-film shape, they showed more than 80% visible light transmittance and a higher gas permeability of 58.7 g/m2 h than the human transepidermal water loss. Simultaneous and independent detection of temperature and humidity was achieved with a high sensitivity of 15.9%/°C and 2.5%/percentage of relative humidity, respectively, using two types of gels with ionic liquids.These results suggest that the easily modifiable nature of ionic liquids contribute to the development of stretchable electronics.

Carboxymethyl chitosan capped copper oxide nanomaterials as antibacterial and antibiofilm coating for vulcanized natural rubber film

The constant menace of infections caused by many microorganisms is one of the significant concerns to humankind. Also, implant-associated biofilms are prevalent in the healthcare sector, which opens up the need for various protective armories against diseases, including antibacterial coatings. In the current context, developing an appropriate antibacterial coating for the materials utilized in the health sector has significance. Synthesis of copper oxide (CuO) nanoparticles (NPs) by the chemical precipitation method and capping of CuO with carboxymethyl chitosan (CMC) provides outstanding antibacterial action. Natural rubber is widely used for various biomedical purposes, regardless its dormancy against most pathogens. An economical and practical method has been developed to transform the Natural Rubber Latex (NRL) film surface to be sufficiently antibacterial by CuO/CMC lamination. This paper discusses the antibiofilm activity of the rubber films against Escherichia coli (MTCC No. 729) and Staphylococcus aureus (MTCC No. 902), and the non-cytotoxicity of the NRL films after CuO/CMC lamination. Hence this surface modification over the NRL film provides excellent prospects for antibacterial polymer materials.