Effective Damping Temperature Range Research Articles

Synthesis and research of basalt microfiber‐reinforced polyurethane elastomer composites

AbstractBasalt microfiber‐reinforced polyurethane elastomer composites (BMF/PUE) were prepared by semi‐prepolymer method in this study. The degree of microphase separation and quantitative analysis of H‐bonding formation in polyurethane were determined by infrared spectroscopy. The fiber surface and the morphology at the tensile fracture interface of the composite materials were observed by scanning electron microscopy. The mechanical properties of composite materials were further measured on an electronic universal testing machine. Dynamic thermomechanical analysis and acoustic impedance tube were used to study the damping and acoustic properties of composite materials, respectively. The results indicated that the composite material prepared by adding 6 g of basalt microfibers treated with 3 min' crushing had the best overall performance. Compared with the matrix, BMF/PUE showed good sound insulation performance with a much wider effective damping temperature range. On the basis of ensuring its excellent overall performance, the mechanical properties were increased by 50.4% in tensile strength, 28.1% in elongation at break, and 14.2% in tear strength.

Damping and Electromechanical Behavior of Ionic-Modified Brominated Poly(isobutylene-co-isoprene) Rubber Containing Petroleum Resin C5

To improve the damping properties of rubbers, organic tackifiers such as hydrocarbon resins, rosin esters, and polyterpenes are often incorporated to increase the intermolecular friction of the rubber, thus increasing the energy dissipation (damping) during dynamic loading. However, this is often at the expense of the cross-linking density and mechanical properties of the rubbers. Ionic cross-links introduce unique properties to rubbers, such as a combination of mechanical reinforcement and high extensibility, as well as self-healing and damping, thanks to the reversible ionic association. Hence creating an ionic network would be an interesting alternative to adding small molecular tackifiers to rubbers. The reversible ionic association inevitably causes structural instability over time (i.e., creep) or at elevated temperatures (ionic transition generally happens at 60–80 °C). To balance the dynamic damping, viscoelasticity, and mechanical stability of these materials, we prepared 1-vinyl imidazole modified brominated poly(isobutylene-co-isoprene) (BIIR) elastomers by solid-state rubber compounding and curing processes, and we investigated the effects of ionic networks and an aliphatic petroleum resin (C5) on the viscoelastic and electromechanical properties of the ionic-cross-linked elastomers. We found that the mechanical reinforcement can be achieved simultaneously with a broad effective damping temperature range through optimizing the ionic network and C5 concentrations. The polar ionic clusters also increased the dielectric permittivity while maintaining a low dielectric loss of the elastomers. The ionic modified BIIR exhibited actuation and energy harvesting properties similar to those of the commercial VHB-4910 elastomer under similar configurations, which provides alternative dielectric elastomers with reprocessability for vibration and energy harvesting applications.

Structure and performance control of high‐damping bio‐based thermoplastic polyurethane

AbstractThermoplastic polyurethane (TPU) has become the focus of attention in the green and sustainable materials field because of its superior processability and recyclability. In this paper, a series of polylactic acid (PLA) and polycaprolactone (PCL)‐based TPUs were successfully prepared by selecting PLA glycol, PCL glycol, isophorone diisocyanate (IPDI) and 1,4‐butanediol (BDO) through a one‐step polymerization method. The properties of the PLA and PCL‐based TPUs are comprehensively characterized by Fourier transform infrared spectroscopy, 1H NMR spectra, gel permeation chromatography, differential scanning calorimetry, thermalgravimetric analyzer, tensile test, dynamic mechanical analysis, scanning electron microscope, and so forth. The effect of hard segments content and PLA glycol molecular weight on the properties of PLA and PCL‐based TPUs was systematically studied. Notably, their performance shows a certain degree of regularity and can be controlled by adjusting the hard segments content or the molecular weight of the PLA glycol. The prepared PLA and PCL‐based TPUs have a tensile strength of 24.71 MPa, excellent thermal stability and out‐standing damping performance. Its tan δ max of 1.40 and an effective damping temperature range of 50°C also make it a green damping material with great potential.

Effects of boron nitride and carbon nanotube on damping properties, thermal conductivity and compression stress relaxation behavior of BIIR

AbstractAs highly integrated electronic components and devices are used under high electrical power and mechanical vibration, the thermal conductivity, damping properties, and compression stress relaxation of protection materials have become critical factors which affect the long‐term durability and reliability of the materials. Damping rubbers are widely used, but their thermal conductivity and compression stress relaxation are rarely studied. Herein, the effects of boron nitride (BN) and carbon nanotube on the damping properties, thermal conductivity, and compression stress relaxation behavior of brominated butyl rubber (BIIR) are investigated. BN increases the damping factor of BIIR and widens its effective damping temperature range. The maximum damping factor of BIIR composite with 12.3 wt% BN is 0.95, and the effective damping temperature range is −41 to 60°C. Moreover, the thermal conductivity of BIIR with 12.3 wt% BN is 0.46, much higher than that of BIIR. With increasing BN content, the thermal conductivity of BIIR/BN composites increases gradually, while their stress relaxation rate decreases. Carbon nanotube can further increase the thermal conductivity of BIIR/BN composites. BIIR/BN composites with high damping properties and thermal conductivity have a great application potential in the heat dissipation and vibration reduction of electronic devices.

MoS2/CF synergistic reinforcement on tribological properties of NBR/PU/EP interpenetrating polymer networks

NBR based water-lubricated bearings have attracted tremendous attention with the dramatic oil leakage pollution of oil-lubricated bearings even the implementation of environmentally friendly and ecologically sustainable development strategies. In this paper, MoS2 and CF are used to reinforce NBR based IPNs composites. Results reveal that the damping factor of fillers/IPNs composites reaches to 0.75 and their effective damping temperature range accomplishes to 50.3 ℃. The minimum friction coefficient and wear rate are 0.033 and 3.09 × 10−5 mm3/Nm respectively, which is decreased by 51 % and 68 % compared with original IPNs. This indicates that MoS2 and CF have a brilliant synergistic effect on improving damping and tribological properties of IPNs, which is attributed to the prominent dispersion of CF and its synergistic effect with MoS2. The knowledge obtained in this work will be promising for preparing water-lubricated bearings materials with excellent damping and tribological performances.

Preparation and molecular dynamics study of polyurethane damping elastomer containing dynamic disulfide bond and multiple hydrogen bond

Using damping materials is an effective measure to control vibration and noise, which is widely used. However, it is relatively difficult for polymer damping materials to find a balance between damping and mechanical properties. Herein, a polyurethane is designed containing dynamic disulfide bonds and hydrogen bonds of different strength to address the dilemma. The polyurethane is endowed with good damping and mechanical properties (effective damping temperature range of 117 °C and a tensile strength of 14.98 ± 0.50 MPa). The molecular dynamics were studied by combining dynamic mechanical analysis (DMA) and broadband dielectric relaxation spectroscopy (BDRS). The microphase separation morphology and degrees of separation were used to help explain molecular dynamics. The segmental motion of soft phase becomes difficult in the glass-transition temperature (Tg) and faster in a high temperature with increasing 2, 2′-Dithiodibenzoic acid (DTSA) contents. These results explain the mechanism improving damping performance and provide some references for designing damping materials in the future.

A novel ternary interpenetrating polymer networks based on NBR/PU/EP with outstanding damping and tribological properties for water-lubricated bearings

Water-lubricated bearing is an indispensable component in propulsion systems on the ship and submarine. Currently, when water-lubricated bearing operates, enormous device damages caused by wear loss and friction-induced vibration of bearing materials will result in lack of concealment and safety. Therefore, a higher performance bearing material is urgently needed. In this paper, a novel kind of ternary Nitrile butadiene rubber/Polyurethane/Epoxy (NBR/PU/EP) interpenetrating polymer networks (IPNs) are successfully prepared and the damping and tribological properties are systematically investigated. Results show that NBR/PU/EP IPNs with a mass ratio of 100:40:60 possess the widest effective damping temperature range, lowest coefficient of friction and specific wear rate under water lubrication conditions. Excellent damping and tribological properties are attributed to unique micro-phase continuous structure evidenced by TEM analysis. The present work is expected to provide a new idea and practical basis for preparing higher performance rubber-based water-lubricated bearing materials.

Temperature- and frequency-dependent vibroacoustic response of aluminium extrusions damped with viscoelastic materials

Viscoelastic materials are commonly used as damping materials for noise and vibration control in composite structures. However, their effective damping temperature range is usually extremely narrow, and a comprehensive understanding of their temperature- and frequency-dependent properties is lacking. Therefore, in this study, we analyse the temperature- and frequency-dependent vibroacoustic response of aluminium extrusions damped with viscoelastic materials. First, three kinds of modified butyl rubbers with the best damping performance at different temperatures were fabricated. Their glass transition temperatures were measured using differential scanning calorimetry, and their temperature- and frequency-dependent damping loss factors and elastic moduli were determined through dynamic mechanical analyses and using the time–temperature equivalence rule. Subsequently, to practically apply the viscoelastic materials to a high-speed train carbody, the heat transfer characteristics of aluminium extrusions were analysed using the finite element method, and the vibroacoustic behaviours of the composite structure were investigated considering the temperature- and frequency-dependent damping loss factors and elastic moduli of the viscoelastic materials. Finally, the key parameters of the viscoelastic materials that affect the radiated sound power of the composite structure were discussed, and multilayer damped aluminium extrusions using three different viscoelastic materials were analysed. The results demonstrate that in order to control the noise and vibration of composite structures over a wide range of temperatures, not only the temperature range and damping performance of viscoelastic materials should be broadened and improved, respectively, but also the damping loss factor and elastic modulus should be matched considering temperature and frequency variations.

Damping efficiency of two-layer polyurethane composites

In this work, based on the results of dynamic mechanical studies, the damping efficiency of two-layer polyurethane (PU) composites designed by gluing two films of synthesized PU with different glass transition temperatures (Tg) was estimated. The damping efficiency was estimated by the parameters of the mechanical losses (tanδ) peak. To vary Tg, three types of PU with different chemical nature and structure were synthesized. The effect of an increase in the difference between the Tg of the initial PU (ΔTg) on the damping efficiency of the two-layer PU composites formed from them is analyzed. The effective damping temperature range (ΔT) was estimated as the temperature range under conditions tanδ ≥ 0,3 and tanδ ≥ 0,6. It was shown that at ΔТg = 7 °С a two-layer PU composite has one relaxation maximum, and its temperature range of damping efficiency expands in comparison with ΔТ for individual PU. Under the conditions ΔТg = 23 °С and ΔТg = 30 °С, two-layer PU composites exhibit damping efficiency in two temperature regions at tanδ ≥ 0,3, which provides an additional temperature range of effective damping. The essential role of the PU structure of each of the layers in the formation of a two-layer composite by gluing has been determined. Easier penetration of residues of the adhesive organic solvent into the surface of the PU film with a linear structure leads to plasticization of the corresponding layer in the composite and reduces Tg. It is shown that a two-layer structure can be used to solve specific problems related to the adjustment or broadening the effective damping temperature range.

Effects of chain structure on damping property and local dynamics of phenyl silicone rubber: Insights from experiment and molecular simulation

The dynamic mechanical property of silicone rubbers with different phenyl units and phenyl contents were comprehensively investigated by means of experiments combined with molecular dynamics (MD) simulation. Experimentally, the results indicate that the phenyl units are randomly distributed in the polymer chains and the damping capacity is considerably improved with the augment of phenyl contents. Compared with methylphenyl units, diphenyl units endow the silicone rubber with enhanced mechanical stability, which leads to a wider glass transition region and effective damping temperature range. Furthermore, the MD simulation reveals the equilibrium structures and local dynamics by monitoring the changes of molecular interactions, bond rotation, conformational transition and molecular diffusion during the cooling process, which correlates the dynamic mechanical response to the molecular relaxation behavior. This work provides a deeper insight into the relationship among the composition, microstructure and damping property, which may promote theoretical predictions and scientific basis for the designs of silicone rubber with desired performances.

Stable ion bond for high damping, high wet resistance, and low rolling resistance high vinyl polybutadiene rubber‐based dicarboxylate ionomer

AbstractSince the implementation of European Union (EU) tire label, the focus of recent attention has been focused on high performance green tire with low rolling resistance, high wet resistance, low noise, and excellent auto‐braking properties. However, it is a significant challenge to simultaneously achieve these performances for rubber materials. In this research, we developed a novel concept on the construction of stable ion bonds for high performance high vinyl polybutadiene rubber (HVBR)‐based dicarboxylate ionomers. HVBR‐based dicarboxylate sodium ionomer (hereafter referred as Na ionomer) was fabricated through complexation reaction of some or all of carboxylic functional groups on the preprepared maleinized HVBR molecular chains with sodium hydroxide. In the case of Na ionomers, the formation of sodium carboxylate group was certified from Fourier transform infrared spectra. Physical and dynamic mechanical measurements indicated that the tensile strength, wear resistance, wet skid resistance, dry sliding resistance, low rolling resistance, and low heat buildup of the Na ionomer were significantly improved compared to that of HVBR, and Na ionomer simultaneously showed better damping properties and the effective damping temperature range was broadened from −8.8 to 30.1°C, which was closer to the room temperature. Consequently, the approach and results collectively represent a significant advance toward the development of high performance green tire rubber materials.

Effect of Aromatic Petroleum Resin on Damping Properties of Polybutyl Methacrylate.

The damping properties of polybutyl methacrylate (PBMA)/aromatic petroleum resin (C9) composite were investigated in this work. In particular, a trace of styrene (St) was introduced to copolymerize with PBMA to improve the compatibility between C9 and matrix. The structure of the copolymer, P(BMA-co-St), was characterized by FTIR and 1HNMR. The P(BMA-co-St)/C9 composites were tested by differencial scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamical mechanical analysis (DMA). DSC curves of all P(BMA-co-1wt%St)/C9 composites expressed only one glass transition temperature (Tg). SEM images showed that C9 had good compatibility with the matrix after St was introduced. DMA curves indicated that the addition of C9 had a positive effect on the damping properties of PBMA. The loss tangent (tanδ) peak moved to a higher temperature with the increment content of C9, and the effective damping temperature range increased significantly. The influence of aromatic resin C9 and aliphatic resin (C5) on PBMA damping performance was compared. It was further shown that C9 with benzene ring effectively improved the damping performance of PBMA.

Evaluation of new aspect of styrene-butadiene-styrene modified bitumens: Damping property and mechanism

Damping is essential to bearing dynamic loads of construction structures, such as bridges, pavements, and high-speed rails. This paper presents a novel and preliminary understanding of the damping property and mechanism of styrene-butadienestyrene modified (SBS-modified) bitumens. The damping property was evaluated based on the temperature spectra of the loss factor (LF) by a dynamic shear rheometer and the damping mechanism was interpreted from molecular structure, morphology, and thermal analysis, respectively. The results first demonstrated that the SBS-modified bitumens appeared to maintain good damping property with a wide effective damping temperature range, low damping temperature susceptibility, and relatively high LF in normal working temperature range of pavement. In addition, the damping property seemed to be further improved separately by the crosslinker and plasticizer and the synthetic role on improving damping capacity was also observed by the combination of these two additives. Furthermore, the damping property of the SBS-modified bitumens appeared to be considerably influenced by temperature and the integrity of the hybrid via polymers blending and the use of additives. It was noted that the plasticizer promoted the swelling process of SBS polymers, by which improved the dispersion and chain movement ability. Moreover, the crosslinker increased the internal friction by forming denser polymer network. The findings in this paper will facilitate the development and application of the SBS-modified bitumen based damping materials in noise and vibration reducing and controlling to some extent.

Design and synthesis of phenyl silicone rubber with functional epoxy groups through anionic copolymerization and subsequent epoxidation

In this paper, we have developed epoxidized phenyl silicone rubber (EMVPQ) with good oil and radiation resistance by anionic ring-opening copolymerization and further epoxidation modification. Silicone rubbers with both phenyl and epoxy groups were firstly synthesized and main properties of the material were characterized. When the phenyl content in EMVPQ was increased from 5% to 20%, the damping loss peak shifted to the high temperature by 36 °C and the effective damping temperature range was widened by 3 °C. The tensile strength of EMVPQ with 20% phenyl content did not change before and after irradiation. When the epoxy content is only 13%, the EMVPQ retained mechanical properties after immersion at 25 °C or 100 °C for 72 h, but a commercial sample substantially lost its mechanical properties. This work not only promotes the research of epoxidized phenyl silicone rubber, but also opens an effective way for the preparation of high-performance aerospace materials.

Preparation and Properties of Rubber Blends for High-Damping-Isolation Bearings

To improve the energy dissipation capacity of rubber isolation bearings, it is important to find a new rubber material with good applicability and high damping properties. Two types of blends were prepared using nitrile rubber (NBR), brominated butyl rubber (BIIR) and ethylene-vinyl acetate copolymer (EVA): NBR/BIIR and NBR/BIIR/EVA. The vulcanization, mechanical and damping properties of the blends were analyzed. The results show that both blends exhibit excellent vulcanization plateaus and mechanical properties. For NBR/BIIR, as the BIIR content increases, the complementary effects of NBR and BIIR afforded by blending are enhanced. Two damping peaks appeared in the tanδ-T curve and shifted toward lower and higher temperatures, respectively, which clearly widened the effective damping temperature range. However, the damping value in the valley of the tanδ-T curve was as low as 0.39. For NBR/BIIR/EVA, the addition of EVA greatly increased damping in the valley of the tanδ-T curve to approximately 0.54. EVA was observed to be the optimal polymer for improving the compatibility of the NBR/BIIR blend. Moreover, hot air thermal aging tests showed that both blends demonstrated good stability.

Design of regulable chlorobutyl rubber damping materials with high-damping value for a wide temperature range

In this paper, a kind of specific damping material with high damping and wide effective damping temperature range (ΔT) was designed by regulating glass transition temperature (Tg). The damping material was prepared based on chlorobutyl rubber (CIIR), which exhibits high initial damping performance but also low Tg and narrow ΔT. 40 phr carbon black (CB) was added to promote the Tg of CIIR as well as acted as the reinforcing agent. Simultaneously, different dosages of terpene resin (TR) were incorporated to further control the Tg and ΔT, and improve the interfacial compatibility between CIIR with CB. Consequently, the Tg and ΔT of the composites could be regulated by changing the amount of TR under the premise of ensuring good damping and mechanical properties. Especially, when the content of TR was 30 phr, the Tg of composite was tuned from −30 °C of blank sample to 0 °C and ΔT was widen from (−60 °C, 35 °C) to (−60 °C, 60+ °C). Maximum loss factor (Tanδmax) was increased from 1.1 to 1.3 as well. In addition, this kind of damping material possessed outstanding actual shock absorption and noise reduction performances corroborated by resonance test and noise reduction test. Therefore, this damping material shows great potential in high-quality damping rubber products.

Preparation of polyurethanes with broad damping temperature range and self-healing properties

It is urgent for polyurethane (PU) damping materials to broaden the effective damping range. Based on the designability of PU, this study is focused on the role of long dangling chain, wherein prepared by the reaction of polyethylene glycol monomethyl ether with toluene-2,4-diisocyanate. Notably, the introduction of long dangling chain not only makes the dangling chain longer and enhances the intermolecular interaction but also equips the dangling chain with strong polar carbamate group, bringing about more excellent compatibility of the soft and hard segments and lower degree of microphase separation under the condition of hydrogen bonding. The results show that the damping performance increases with the synergistic effect of significant hydrogen bonding and decreased degree of microphase separation, and the effective damping temperature range (tan δ ≥ 0.3) can exceed 150°C (−50°C to 100°C). Simultaneously, the addition of long dangling chains endows PU with self-healing property, the self-healing rate of system reaches maximum 70% with shore A hardness of 15 because of the synergistic effect above with the addition of 60% dangling chain, which extends the service life of PU damping materials.

Damping, thermal, and mechanical performances of a novel semi‐interpenetrating polymer networks based on polyimide/epoxy

ABSTRACTIn this article, a series of novel semi‐interpenetrating polymer networks (s‐IPNs) based on linear polyimide (PI) and crosslinked epoxy (EP) were firstly prepared aiming at controlling violent vibration and noise originating from operation of the machine. The damping, thermal, and mechanical performances of s‐IPNs films were systematically investigated in terms of the structure of polyimide (the molar ratios of diamines) and the component ratios of PI/EP. The results indicate that PI/EP s‐IPNs films exhibit prominent damping properties, and the effective damping temperature range can reach up to 58.8 °C when molar ratio of diamines is 1:3 within PI and component ratio of PI/EP is 70:30. Meanwhile, all the PI/EP s‐IPNs films show good thermal stability compared to cured EP and certain mechanical behaviors due to the formation of semi‐interpenetrated structure. Meaningfully, the prepared novel PI/EP s‐IPNs will be used as effective damping materials and have a potential application in damping fields. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48032.

Understanding damping performance and mechanism of crumb rubber and styrene-butadiene-styrene compound modified asphalts

Abstract This paper presents a preliminary study of the damping performance (DP) and mechanism of crumb rubber modified (CRM) asphalt. The loss factor (LF) temperature spectra of a dynamic shear rheometer was applied to evaluate the damping performance of crumb rubber (CR) and styrene-butadiene-styrene (SBS) compound modified (CSCM) asphalts using with four criteria. The results showed that CSCM asphalts exhibited a good damping performance with a wide effective damping temperature range, low damping temperature susceptibility, and relatively high LF in normal working temperature range of pavement. This finding served as an indirect but novel explanation for the superior noise reduction of CRM asphalt pavement. Then, an initial investigation of the damping mechanism of CSCM asphalts was conducted by analyzing molecular structure, thermal behavior, and morphology. The results showed that the integrity (synergistic effects of each component in the polymer system) strongly influenced the damping performance of CSCM asphalts through the temperature and blending of polymers and additives. The finding would facilitate the application of CRM asphalts-based damping materials, which can assist to develop sustainable solutions to tackle worldwide environmental problems to some extent.

A direct polymerization approach toward hindered phenol/polymer composite latex and its application for waterborne damping coating

The building of polymer composite particles in their confined colloidal-scale space is a highlighted topic, leading to advanced structure complexity and high performance in functional coating applications. Here, we demonstrate a direct emulsion polymerization (EP) approach to synthesize composite latex with hindered phenol (HP), a kind of functional small molecules, successfully loaded inside colloidal polymer particles. Monomer conversion as well as the evolution of droplet/particle size has been traced as a function of polymerization time. The results evidence the smooth running of the polymerization process with high HP loading in situ in the aqueous dispersion which could reach 30 phr. As-synthesized HP/polymer latex could be conveniently used for the formation of coating films. The films are unique for the greatly improved damping properties. With HP content of 30 phr, the effective damping temperature range can be broadened to 112 ℃, and the a maximum loss factor can rise to 2.7. The weak hydrogen bonding is found to be the key for the incorporation of HP with the polymer segments, and contributes to the dissipation of vibration energy in the films. Combined with the environmental benefits, waterborne composite latex here is of potential application for the building of green damping coating systems.