Rubber Device Research Articles

Prediction of the optimal vulcanization of a fiber‐reinforced elastomeric isolator made of natural rubber‐ethylene propylene diene monomer blend

AbstractTo seismically isolate a structure, it is possible to interpose a rubber device between the foundation and superstructure that increases the period of the superstructure, a feature that allows the structure to be “transparent” to the seismic excitation. A package of several rubber pads typically constitutes a seismic isolator; they are 10–20 mm thick vertically interspersed with either steel laminas or fiber‐reinforced polymer dry textiles suitably treated. So, the rubber has a primary role and must be vulcanized correctly to create the polymer cross‐linking properly. All rubber mechanical properties are strongly affected by curing temperature and curing time. Under vulcanization is a typical production error that suppliers make in large‐scale productions, especially when the size of the devices is considerable. It is common to deal with elastomeric isolators where rubber pads have been treated at a largely suboptimal temperature. This article proposes a numerical model for predicting the cross‐linking degree of rubber pads used in seismic isolation and made by a natural rubber‐ethylene propylene diene monomer rubber compound. The aim is to correctly define the optimal curing temperature and exposition time for producing a rubber quadruple shear test specimen and a fiber reinforced elastomeric isolator (FREI). The model is a kinetic one and takes into consideration the induction time. An experimental investigation has been conducted to validate the model with visible inspections and hardness measurements taken on the rubber pads (quadruple shear specimens) and the rubber devices. The results have shown the reliability of the new numerical model proposed, with a homogeneous mechanical properties distribution obtained within the rubber pads and the FREI.

Natural silk-composite enabled versatile robust triboelectric nanogenerators for smart applications

Strategies to maximize the surface charge density across triboelectric layers while protecting it from humidity are crucial in employing triboelectric nanogenerators (TENGs) for commercial/real-time applications. Herein, for the first time, we propose the utility of crystalline silk microparticles (SMPs) to improve the surface charge density in materials like polyvinyl alcohol to realise its applicability for TENG devices. Moreover, these SMPs are extracted from discarded Bombyx mori silkworm cocoons by facile, inexpensive, and single-step alkaline-hydrolysis treatment. We examine the performance of these composites with counter-materials composed of waste PTFE plastic cups to show reuse in recycled products. The processing cost of TENG developed from recycled materials is not only low but eco-friendly. The TENG performance as a function of the concentration of SMPs is investigated and compared with the composite's work-function and surface-potentials, with the distance-dependent electric field theoretical model employed to optimize the performance. Consequently, the optimized TENG exhibits maximum output voltage, current, charge, and power density of ∼280 V, 17.3 μA, 32.5 nC, and 14.4 W·m−2, respectively, creating a highly competitive energy harvester that can conform to the rigorous needs of wearables and mobile applications. Furthermore, the fully packaged silicone rubber device protects it from humidity and enables the device utility for practical applications with a soft, comfortable, and skin-friendly interface.

Brain mechanisms of social touch-induced analgesia in females

Supportive touch has remarkable benefits in childbirth and during painful medical procedures. But does social touch influence pain neurophysiology, ie, the brain processes linked to nociception and primary pain experience? What other brain processes beyond primary pain systems mediate their analgesic effects? In this study, women (N = 30) experienced thermal pain while holding their romantic partner's hand or an inert device. Social touch reduced pain and attenuated functional magnetic resonance imaging activity in the Neurologic Pain Signature (NPS)-a multivariate brain pattern sensitive and specific to somatic pain-and increased connectivity between the NPS and both somatosensory and "default mode" regions. Brain correlates of touch-induced analgesia included reduced pain-related activation in (1) regions targeted by primary nociceptive afferents (eg, posterior insula, and anterior cingulate cortex); and (b) regions associated with affective value (orbitofrontal cortex), meaning (ventromedial prefrontal cortex [PFC]), and attentional regulation (dorsolateral PFC). Activation reductions during handholding (vs holding a rubber device) significantly mediated reductions in pain intensity and unpleasantness; greater pain reductions during handholding correlated with greater increases in emotional comfort, which correlated with higher perceived relationship quality and (a trend toward) greater perceived closeness with the romantic partner. The strongest mediators of analgesia were activity reductions in a brain circuit traditionally associated with stress and defensive behavior in mammals, including ventromedial and dorsomedial PFC, rostral anterior cingulate cortex, amygdala/hippocampus, hypothalamus, and periaqueductal gray matter. Social touch affects core brain processes that contribute to pain and pain-related affective distress in females, and should be considered alongside other treatments in medical and caregiving contexts.

Reduced order models for dynamic behavior of elastomer damping devices

In the context of passive damping, various mechanical systems from the space industry use elastomer components (shock absorbers, silent blocks, flexible joints,…). Among other specificities, elastomers have frequency dependent characteristics. The computational cost of the associated numerical models, using viscoelastic constitutive behavior, may become too expensive during a design process. To solve this problem, the aim of this work is to propose an efficient reduced viscoelastic model of rubber devices. The first step is to choose an accurate material model that represents the viscoelasticity. The second step is to reduce the rubber device finite element model to a super-element that keeps its frequency dependent properties. This reduced model is first built by taking into account the fact that the device's interfaces are much more rigid than the rubber core. Therefore, kinematic constraints enforce the rigid body motion of these interfaces, reducing them to twelve degrees of freedom only (three rotations and three translations per face). The super-element is then built by condensing the core of the finite element model on the interfaces via a Component Mode Synthesis (CMS) method, adapted here to viscoelastic damping. As an application, the dynamic behavior of a structure supported by four rubber devices under harmonic loads is analyzed to show the efficiency of the proposed approach.

Reduced Order Models for Dynamic Behavior of Elastomer Damping Devices

In the context of passive damping, various mechanical systems from the space industry use elastomer components (shock absorbers, silent blocks, flexible joints...). The material of these devices has frequency, temperature and amplitude dependent characteristics. The associated numerical models, using viscoelastic and hyperelastic constitutive behaviour, may become computationally too expensive during a design process. The aim of this work is to propose efficient reduced viscoelastic models of rubber devices. The first step is to choose an accurate material model that represent the viscoelasticity. The second step is to reduce the rubber device finite element model to a super-element that keeps the frequency dependence. This reduced model is first built by taking into account the fact that the device's interfaces are much more rigid than the rubber core. To make use of this difference, kinematical constraints enforce the rigid body motion of these interfaces reducing the rubber device model to twelve dofs only on the interfaces (three rotations and three translations per face). Then, the superelement is built by using a component mode synthesis method. As an application, the dynamic behavior of a structure supported by four hourglass shaped rubber devices under harmonic loads is analysed to show the efficiency of the proposed approach.

Pressure Monitoring of Multilayer Inelastic Bandaging and the Effect of Padding in Breast Cancer–Related Lymphedema Patients

This study of pressure monitoring of multilayer inelastic bandaging and the effect of padding in breast cancer-related lymphedema patients aimed to measure the resting and working sub-bandage pressures in compression therapy for lymphedema patients and to determine whether applying additional padding has an additional effect in volume reduction of the limb. Forty-eight patients with breast cancer who were beginning complex decongestive therapy for lymphedema were included. In 24 patients, padding was added to the forearm. A short-stretch bandage with or without padding was applied to the affected arm. The working pressure was measured while the patients squeezed a rubber device. The forearm limb circumference was measured before and after 2 wks of treatment. The mean (SD) of the resting pressure was 36.3 (2.2) mm Hg without padding and 49.5 (3.2) mm Hg with padding. The mean (SD) of the working pressure was 9.5 (3.7) mm Hg without padding and 24.3 (9.1) mm Hg with padding (P < 0.05). The volume loss after treatment was significantly greater in the group with added padding (P < 0.05). The working pressure during exercising with a force of 50 Pa is approximately 10 mm Hg with a short-stretch bandage applied. Adding a pad increases both the resting and the working pressure and also seems to be effective in increasing volume reduction of the limb.

Predictive Functional Control of Stiffness-changeable Finger Using Soft Rubber Device

Predictive Functional Control of Stiffness-changeable Finger Using Soft Rubber Device

Manual Application of Controlled Forces to Thoracic and Lumbar Spine With a Device: Rated Comfort for the Receiver's Back and the Applier's Hands

Purpose High volumes of manual therapy work can lead to overuse hand and wrist injuries. This study evaluated hand and back comfort in asymptomatic volunteers during spinal mobilization carried out with an instrumented manual therapy tool. Methods This crossover design study examined 36 asymptomatic physiotherapy students that were tested in pairs. One participant assumed the role of the simulated therapist and the other the simulated patient, before reversing roles. Posteroanterior mobilization conditions formed by using 2 spinal segments (thoracic/lumbar), 2 force application methods (hands/device), and 3 grades of mobilization were applied in a random order. After each combination, both participants in each pair rated hand or back comfort, respectively, on a 100-mm visual analogue scale. Data were analyzed by analysis of variance. Results Rated back comfort was greater for hands than for the device and decreased with greater applied force. When the original hard rubber device tip was changed to one of soft molded rubber, both back and hand comfort improved significantly. Although tool mobilization was still rated as significantly less comfortable than mobilization with hands only, this difference was approximately half the discomfort experienced as the grade of mobilization increased from grade I to grade III. For hand comfort when using the softer device tip, the method of force application was no longer a significant determinant of comfort. Conclusions The mobilizing tool with a molded rubber tip was acceptably comfortable in use with asymptomatic backs and hands. Further research is indicated in manual therapy settings with therapists who have experienced hand pain.

A POLYMETHYLPENTENE FIBER GAS EXCHANGER FOR LONG-TERM EXTRACORPOREAL LIFE SUPPORT

The Novalung 1.3m2 gas exchange device made of polymethylpentene (PMP) fibers was evaluated in healthy sheep (35–42kg) in order to characterize its performance and potential use in clinical ECLS. Five Novalung PMP devices were compared to 5 Kolobow silicone rubber devices (1.5m2) that were run on veno-venous ECLS for 72 hours. The two device groups were compared for differences in gas exchange, device pressure gradient, hematology, blood biochemistry and pathology. The results showed superiority in the PMP devices in both oxygen and CO2 exchange when compared at similar blood flow rates. Platelet consumption and pressure gradient were significantly less when using the PMP device. The pressure gradient across the PMP devices was 20mmHg as compared to >150mmHg for the silicone rubber devices at all blood flow rates. Changes in plasma hemoglobin, leukocytes, blood chemistries and pathological findings were not significantly different between the two device groups. Plasma leakage or device failure did not occur in any of the test devices. Overall, the Novalung PMP device performed better than the Kolobow ECMO 1500 silicone rubber device. These data support the use of the PMP device for extended circulatory support. Patients may fare better due to better biocompatibility and the low resistance may allow for wider use of centrifugal style pumps or the use of the device in a pumpless arterio-venous mode.

Kumacone II: an adapter to aid in the placement of a purse-string suture in very low anterior rectal resection.

We have designed an adapter called the "Kumacone II", being a bottle-shaped rubber device which greatly aids in placing a purse-string suture, even at the lowest level near the anorectal junction of the rectum. When this adapter is used, performing the anastomosis is much less time-consuming and not as much training is needed as for low anterior resection using conventional manual suturing. In a clinical study, the incidence of leakage and incontinence was nil in five out of five patients.

Vibration preventive rubber device for automobiles

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The Cervical Cap

The cervical cap may eventually prove to be a safe, satisfactory, noninvasive, and nonhormonal contraceptive alternative for women in the US. The cap is currently approved for investigational use only, and is available from a limited number of providers. The Prentif cavity rim cap is the most commonly used and is available in 4 sizes. The soft rubber device is thimble shaped, approximately 1 1/4 inches long, with a narrow groove along the inner surface that creates a suction seal when fitted over the cervix. The inability to match cap and cervical circumferences precisely is a recognized drawback. Theoretically, the cap alone should prevent sperm entry into the uterus, however, the use of a spermicide placed in the dome before insertion is recommended. The cap's effectiveness is not yet documented. Estimates from a 1953 study of 143 users were 92.4/100 women years of use for use effectiveness, and the theoretical effectiveness is believed to be more than 98%. Failures with the cap may result from a variety of reasons, particularly dislodgement. The advantage of the cap over other barrier methods is that it can be inserted any time prior to intercourse and left in place longer. The ideal safety period for placement has not been validated, but a range of 1-7 days has been recommended. The length of time the spermicide remains effective and the cervical effects of prolonged contact are of prime concern. The cap may be used by some women who cannot be properly fitted for a diaphragm due to vaginal or uterine anomalies. Sexual arousal and orgasmic response are reported by some cap users to be more pleasurable with the cap than with the diaphragm. Reported problems with use include discomfort during intercourse and improper fit during some days of the menstrual cycle. Contraindications for use include cervical inconsistencies, infection, allergy to the spermicide or the rubber, and inability to learn proper insertion and removal techniques. Insertion and removal may be difficult, and clients should be given sufficient time to practice. Cap placement needs to be checked manually after insertion and intercourse. With proper use, cleaning, and storage, the cap will last for several years. Instruction in use requires a significant amount of the practioner's time and methods must be sensitive to the client's needs. Attitudes of practitioners and other staff may impact on the acceptability of this method. Additional research is needed on the characteristics of cap users, partners' attitudes, the need to use spermicides, the length of time of spermicidal effectiveness and cap effectiveness rates. Further development of instructional methodologies is needed.

A Brief Note on Rubber Technology and Contraception: The Diaphragm and the Condom

The 19th century development of rubber technology which made possible the widespread use of condoms and the growth of the contraceptive industry is outlined. The use of pessaries for medical as well as contraceptive purposes enabled their history to be traced. The Mensinga pessary of 1842 was a widely used early rubber contraceptive device; in its later version it incorporated a vulcanized rubber diaphragm held in place by a coiled spring. A rubber device similar to the Mensinga diaphragm was introduced into the U. S. in the early 1860s but pamphlets recommending its use were destroyed under the Comstock act. Several pessaries not labelled as contraceptive devices were patented in the 1870s but it was not until 1923 that contraceptive diaphragms were mentioned in respectable American medical journals. Condoms were more widely used but less is known about their early history than is the case with diaphragms. Manufacture of rubber condoms was apparently possible by the 1850s. The first types were designed to cover only the tip of the penis but by 1869 a regular condom is mentioned in the literature. Rubber condoms were ubiquitous by 1900 and were often effective. The seamless cement process was the standard manufacturing technique until well into the 20th century. Quality control remained a problem until after World War II when the U. S. government entered the field.

The abortifacient and oxytocic effects of an intravaginal silicone rubber device containing a 0.5 per cent concentration of 15(S)-15-methyl-prostaglandin F2α methyl ester

Abortion was successfully induced by intravaginal insertion of a silicone rubber device impregnated with an 0.5 per cent concentration of 15(S)-15-methyl-prostaglandin F2α methyl ester in 20 of 25 patients by prostaglandin alone and in an additional three patients by prostaglandin with a concomitant oxytocin infusion. The mean abortion time for the 23 successful abortions was 15.46 hours. Uterine activity was monitored in six patients and uterine response to the vaginal insertion of the prostaglandin-impregnated device was characterized by a gradual rise in amplitude of contractions and intrauterine baseline tonus accompanied by a rapid increase in the frequency of contractions. Induction of abortion by intravaginal administration of a silicone rubber device impregnated with prostaglandin eliminates the hazards associated with intra-amniotic instillation and offers the advantage of a single administration with the option of reversibility if a patient should be hypersensitive to the drug.

Silicone rubber radium carriers for the treatment of nasopharyngeal carcinomas

A silicone rubber device can be constructed that will provide supplemental radiation therapy to patients with recurrent nasopharyngeal carcinoma. This technique provides for direct visualization of the nasopharynx and the advantage of an afterloading technique.

Sock inner sole

White fibrous connective tissue is stimulated to proliferate in areas of low metabolic activity and matures to become sear tissue. In a broad sense its purpose is to pull injured parts of the body together. By gradually increasing the controlled activity of the injured part, the metabolic activity of the part is gradually increased and scar tissue proliferation is gradually decreased. The sock inner sole is a semi-soft, inert, washable, laminated gauze and silicone rubber device of individual pattern to suit any particular case. It protects the injured part and provides a pulsating mechanism to revascularize areas which were treated by free skin grafting or flap grafting. Revascularization is stimulated in the early stages of healing by movements of the foot when sitting; in later stages of healing by movements when sitting and walking. Worn areas on the sock inner sole, after thorough cleansing, are allowed to dry. Silicone rubber and cotton gauze are then applied until the desired shape and thickness of the sock inner sole are obtained.