Materials for vibration damping, including metals, polymers, cement and their composites, are reviewed. Metals and polymers are dominant due to their viscoelasticity. Damping enhancement mainly involves microstructural design for metals, interface design for polymers and admixture use for cement.

Review: Materials for vibration damping

Gradient copolymers with gradients in composition along the chain lengths are synthesized by controlled radical polymerization, and their damping behaviors are compared to those of random and block copolymers. The effect of comonomer incompatibility is studied by comparing behaviors of strongly segregating styrene/4-hydroxystyrene (S/HS) and moderately segregating styrene/n-butyl acrylate (S/nBA) copolymers. The effect of composition gradient steepness is studied by designing “constant” or “increasing” gradients via the comonomer addition rate during semibatch polymerization. Dynamic mechanical analysis (DMA) is used to compare the temperature dependences of the storage modulus (E′), loss modulus (E″), and tan δ of the materials. A glass transition breadth (ΔTg) is defined by a temperature range over which E′ decreases from 109 Pa to 108 Pa. The gradient copolymer ΔTgs are at least four times larger than the random copolymer ΔTgs. The S/nBA gradient copolymers show strong effects of gradient steepness on ΔTg, with ΔTg being much larger for the increasing gradient than for the constant gradient. DMA data are compared to predictions by Hashimoto et al. for tapered block copolymers in the limit where the taper extends across the entire chain. The shapes of their calculated temperature dependences of E′ and E″ correspond well to the gradient copolymers with large ΔTg values, providing strong support for symmetric gradient copolymers forming nanoscale, ordered domains with sinusoidal composition profiles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 48–58, 2008

Gradient copolymers with broad glass transition temperature regions: Design of purely interphase compositions for damping applications

Dynamic mechanical properties and microstructure of an organic hybrid consisting of chlorinated polyethylene (CPE) and 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were investigated. The AO-80 clearly exhibited two second-order transitions at 6 and 69 °C in addition to the melting: the transition at lower temperature is assigned to the glass transition, and the transition at higher temperature is considered to be caused by the dissociation of hydrogen bond between the hydroxyl groups of AO-80. When blending with CPE, part of AO-80 molecules was dispersed into the CPE matrix, and most of them formed an AO-80-rich phase. As a result, a novel transition appeared above the glass-transition temperature of the CPE matrix. It was assigned to the dissociation of the intermolecular hydrogen bond between the α-hydrogen of CPE and the hydroxyl groups of AO-80 within the AO-80-rich phase. Dynamic mechanical properties and microstructure of CPE/AO-80 hybrid were controlled by the thermal treatment. It was found that the CPE/AO-80 hybrid is a good damping material and shows a shape memory effect. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2285–2295, 2000

Organic hybrid of chlorinated polyethylene and hindered phenol. I. Dynamic mechanical properties

The dynamic mechanical properties of binary hybrids of chlorinated polyethylene (CPE) and acrylic rubber (ACM) with 3,9-bis{1,1-dimethyl-2[β-(3-tert-butyl-4- hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) and their ternary hybrids were investigated. The addition of AO-80 was successful in tailoring the damping profile. The ACM/AO-80 hybrids show only one relaxation, which is larger than that of pure ACM, whereas for the CPE/AO-80 hybrids, one novel relaxation appears above the glass-transition temperature of CPE. In the case of CPE/AO-80/ACM, a supramolecular network was formed by a crosslink due to hydrogen bonding. The replacement of a part of CPE by ACM increased the value in the middle of two peaks. The AO-80 molecule, which is a bifunctional hydrogen-bonding acceptor, was found to act as a compatibilizer. In addition, in such ternary hybrids, the tan δ value in the middle of the two peaks was found to be proportional to the slope of the E′ curve at an identical temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2468–2473, 2001

Effects of a hindered phenol compound on the dynamic mechanical properties of chlorinated polyethylene, acrylic rubber, and their blend

Role of graded length side chains up to 18 carbons in length on the damping behavior of polyurethane/epoxy interpenetrating polymer networks

A high performance vibration absorber requires a high loss factor behavior over a wide temperature and frequency range. An investigation was carried out to prepare such materials based on poly(vinyl chloride), chlorinated polyethylene, and epoxidized natural rubber ternary blends. The loss factor and damping behavior of several compositions were measured using a viscoelastic spectrometer and a polymer-laminated steel cantilever-beam damping device. Suitable compositions were found to give good mechanical properties and high loss factor over a wide temperature and frequency range. It was also observed that flake-type fillers improve the damping behavior. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 855–863, 1999

H. Sasaki

Papers

Developments of high performance vibration absorber from poly(vinyl chloride)/chlorinated polyethylene/epoxidized natural rubber blend