Multicomponent latex IPN materials: 2. Damping and mechanical behavior

Controllable Design and Synthesis of Polyurethane Elastomers Containing Polar Dangling Chains with High Mechanical Properties and Wide Damping Temperature Range

Vibration and noise severely affect the operation of mechanical equipment and is also detrimental to human health. Therefore, the development of high performance damping materials is crucial. However, current methods to improve damping properties often come at the expense of mechanical properties, resulting in inferior mechanical performance of materials. In order to address the issue of imbalance between damping properties and mechanical properties in polyurethane damping elastomers. In this study, polyester dangling chains containing polar groups are synthesized and introduced into polyurethane. The obtained polyurethane exhibited an effective damping temperature range of 154 °C (-54 °C to 100 °C) and a tensile strength of 15.82 MPa. Furthermore, dynamic mechanical analysis and broadband dielectric relaxation spectroscopy are combined to investigate the influence of polar dangling chains on the structure and properties of polyurethane. The degree of microphase separation increases after the introduction of polar dangling chains, indicating enhances intermolecular interaction forces, facilitating the formation of hydrogen bond between the main chain and dangling chains, thereby increasing molecular chain friction and energy dissipation. This work overcomes the challenge of balancing the damping and mechanical properties of polyurethane, providing a new strategy for designing high performance polyurethane damping elastomers.

Thermo-Mechanical Properties and Phase-Separated Morphology of Warm-Mix Epoxy Asphalt Binders with Different Epoxy Resin Concentrations

The performance and phase-separated microstructures of epoxy asphalt binders greatly depend on the concentration of epoxy resin or bitumen. In this paper, the effect of the epoxy resin (ER) concentration (10-90%) on the viscosity, thermo-mechanical properties, and phase-separated morphology of warm-mix epoxy asphalt binders (WEABs) was investigated using the Brookfield rotational viscometer, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and laser scanning confocal microscopy (LSCM). Due to the high reactivity of epoxy resin, the viscosity of WEABs increases with time. Furthermore, the initial viscosity of WEABs decreases with the ER concentration. Depending on the ER concentration, the viscosity-time behavior of WEABs is divided into three stages: slow (10-40%), fast (50-80%), and extremely slow (90%). In the slow stage, the viscosity slightly increases with the ER concentration, while the fast stage shows an opposite trend. DSC and DMA results reveal that WEABs with 10-80% ER exhibit two glass transition temperatures (Tgs) for cured epoxy resin and bitumen. Moreover, the Tgs of epoxy resin and bitumen increase with the ER concentration. However, WEAB with 90 % ER has only one Tg. LSCM observation shows that phase separation occurs in all WEABs. For WEABs containing 10-40% ER, spherical epoxy particles act as the discontinuous phase and disperse in the continuous bitumen phase. However, in WEABs with 50-90% ER, phase inversion takes place. Contrarily, bitumen particles disperse in the continuous epoxy phase. The damping properties of WEABs with the continuous epoxy phases increase with the ER concentration, while the crosslinking density shows an opposite trend. The occurrence of phase inversion results in a sharp increase in the tensile strength of WEABs. For WEABs with the continuous epoxy phases, the elongation at break increases with the ER concentration. The toughness first increases and then decreases with the ER concentration. A maximum toughness value shows at 70% ER.

Controllable Design and Preparation of Hydroxyl-Terminated Solution-Polymerized Styrene Butadiene for Polyurethane Elastomers with High-Damping Properties

Vibration and noise are ubiquitous in social life, which severely damage machinery and adversely affect human health. Thus, the development of materials with high-damping performance is of great importance. Rubbers are typically used as damping materials because of their unique viscoelasticity. However, they do not satisfy the requirements of different applications with various working conditions. In this study, the advantages of the high loss factor of styrene butadiene rubber (SBR) are combined with the strong designability of polyurethane. Hydroxyl-terminated solution-polymerized styrene butadiene rubbers (HTSSBRs) with different structures are prepared using anionic polymerization. HTSSBRs are then used as the soft segment during the synthesis of temperature-tunable high-damping performance polyurethane (HTSSBR-polyurethane (PU)). The prepared HTSSBR-PUs with different structures exhibit excellent loss performance, a maximum loss factor (tan δ_max ) of above 1.60, and an effective damping performance over a wide temperature range compared to traditional SBR and polyurethane. Therefore, this work offers an effective method for the design of damping materials with adjustable properties. This article is protected by copyright. All rights reserved.

Damping, Thermal and Mechanical Analyses of Polycarbonate/Cerium Oxide Composites for Structural Applications

Polycarbonate (PC)/cerium (IV) oxide (CeO2) composites are prepared by a melt-compounding method using a twin-screw extruder. The effect of the CeO2 content on the damping property of the composites was investigated using scanning electron microscopy, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). In addition, the composites' mechanical properties were studied through tensile and impact tests. The DMA results revealed that the addition of CeO2 (0.5 wt%) improved the damping property of the composite. TGA showed that the thermal stability was improved when the CeO2 became 1 wt%. Mechanical tests revealed that both the tensile and impact strengths were substantially improved when 1 wt% CeO2 was added. Finally, it can be concluded that the 0.5 wt% CeO2-filled PC composite can be used as a structural damping material.

UDM enhanced physical and mechanical properties through the formation of nanocavities in an epoxy matrix

The matrix modification of relatively low viscous epoxy based polymer treated under ultrasonic mixing (UM) and ultrasonic mixing with simultaneous stirring by a rotating impeller, referred to as ultrasonic dual mixing (UDM), and the effect of processing techniques has been investigated in terms of the formation of nanocavities in the epoxy matrix. Nanocavities of size 42±8nm have been formed uniformly in the epoxy matrix by UDM. The effect of a change in matrix morphology on the viscoelastic, tensile and thermal properties of the cured epoxy resin has been studied. The UDM processed cured epoxy matrix showed 18.26% and 88.34% improvement in tensile strength and toughness as compared to unprocessed epoxy. Thermal gravimetric analysis (TGA) of UDM processed epoxy showed significant enhancement in the thermal stability of the epoxy matrix.

Nanohybrids of organo-modified layered double hydroxides and polyurethanes with enhanced mechanical, damping and UV absorption properties

The construction of high-performance polymer–clay nanocomposites plays an important role in developing new types of organic–inorganic hybrids.

Damping and mechanical properties of polyol cross-linked polyurethane/epoxy interpenetrating polymer networks

A series of glycerol cross-linked polyurethane (g-PU)/epoxy (EP) interpenetrating polymer networks (IPNs) were prepared by sequential method. The functional group change, mechanical properties, morphology, thermal stability, and damping properties were studied. Thermogravimetric analysis result reveals that the thermal stability of these IPNs is enhanced with the increase in the content of g-PU. The result of dynamic mechanical analysis shows that the effective damping temperature range is broadened and (tan δ)max is increased through the introduction of g-PU into EP to form IPNs. Mechanical measurement indicates that the tensile and impact strength of these IPNs reaches the maximum value at the g-PU content of 10%.

Dynamic mechanical properties of polysiloxane-modified, castor oil-based polyurethane/epoxy interpenetrating polymer network composites

A series of hydroxyl-terminated poly dimethyl siloxane (HTPDMS)-modified polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites were prepared. The morphologies of impact fracture surfaces, tensile and impact strengths, damping properties as well as thermal stability properties of the HTPDMS modified IPN composites were studied systematically. The results revealed that the impact strength of the IPN composites could be significantly improved after the incorporation of HTPDMS, whereas the tensile strength of the composites was impaired when the HTPDMS content were more than 5%. The studies also showed that the addition of HTPDMS can improve the damping properties of pure PU/EP IPN and can improve the thermal decomposition temperature. It is expected that the modified IPN composites may be used as structural damping materials.