Micro‐Driving behavior of carbon‐fiber‐reinforced epoxy resin for standing‐wave ultrasonic motor

Multifunctional epoxy resins are inherently brittle due to the extremely high cross‐linking density, thus the enhancement in the toughness is rather important for the industrial application. In this work, a reactive poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate) (PHEMA‐PPG‐PHEMA) is synthesized by using an atom transfer radical polymerization to toughen trifunctional diglycidyl 4,5‐epoxy cyclohexane‐1,2‐dicarboxylate (TDE‐85). A controllable system is constructed, in which the reaction temperature of TDE‐85 with the hydroxyl of PHEMA‐PPG‐PHEMA is lower than with the curing agent. As a result, both heterogeneous and homogeneous structures can be formed in composites through controlling reaction temperature. It is found that the toughness of composites with the heterogeneous structure is effectively improved without sacrificing the tensile strength, tensile modulus, and glass transition temperature. Specifically, the mode‐1 critical stress intensity factor and critical strain energy release rate of TDE‐85/10 wt% PHEMA‐PPG‐PHEMA are increased to 0.77 MPam1/2 and 146 J/m2, respectively, which are effectively enhanced by 32.8% and 70.3%. This can be ascribed to combined toughening effects from the cavitation of the PHEMA‐PPG‐PHEMA phase, the matrix shear yielding, and the enhanced interface bonding strength due to the reaction between TDE‐85 and PHEMA‐PPG‐PHEMA. Thus, this study paves a novel strategy to improve the toughness of epoxy resin by controlling the curing reaction.

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“…f ( x ) is the geometric factor, defined as

f (x) = 6 x^{1 / 2} \frac{([], 1.99 goodbreak- x ((), 1 goodbreak- x) ((), 2.15 goodbreak- 3.93 x goodbreak+ 2.7 x^{2}))}{(1 + 2 x) {((), 1 goodbreak- x)}^{3 / 2}}

where x = a/W and a is the initial notch length including the pre‐crack. The mode‐1 critical strain energy release rate is defined as

G_{1 c} = \frac{(1 - v^{2}) K_{1 c}^{2}}{E}

where E is the elastic modulus acquired from the tensile test and v is the Poisson ratio of the epoxy, which is taken to be 0.34 46 …”

Section: Characterizationsmentioning

confidence: 99%

Synthesis of poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate)reactive block copolymer with controlled reactivity for toughening multifunctional epoxy resin

Zhu

Tang

et al. 2022

J of Applied Polymer Sci

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“…Concurrently, Ishii et al [7] presented a method to predict the service life of USMs that use carbon fiber reinforced polymer as frictional materials, which was verified by the experiment. Subsequently, Lv et al [8][9][10][11][12][13][14] researched a series of polymer-based frictional materials, such as polytetrafluoroethylene (PTFE), phenolic resin, and Ekonol composites, and compared their tribological properties under different conditions to provide guidance for selecting frictional materials according to the operating condition. Wang et al [15,16] systematically studied the effect of fillers, topography, temperature, and vacuum on the wear behavior of PTFE composites and found that filling some functional additives could improve the wear resistance of the PTFE matrix.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of tribological properties of insulated and conductive polyimide composites

Song

Qiu

et al. 2019

Friction

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Insulated polyimide (PI) composites filled with short glass fibers (SGF), polytetrafluoroethylene (PTFE), SiO 2 , and polyphenylene (PPL) are specially designed, prepared, and the tribological properties are systematically investigated with references to the special requirements for frictional materials used in ultrasonic motors. The hardness and thermal decomposition temperature of the insulated PI composites are comparable to that of conductive PI composites. However, these insulated materials present excellent friction and wear performance, especially under high loads and speeds. Scanning electron microscopy (SEM) analysis of the worn surface indicates that adhesive and fatigue wear dominate the wear mechanisms.

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“…Some frictional materials have been tested for USMs, including rubber, resin, metal coatings, alloys, and ceramic composites. It was found that most of them cannot meet the requirements due to, eg, severe wear, short service life, and high noise.…”

Section: Introductionmentioning

confidence: 99%

“…Ishii et al established a method to predict the service life of USMs with a carbon‐fiber‐reinforced polymer as the frictional material. Qu et al investigated the tribological properties of polytetrafluoroethylene (PTFE), phenolic resin, and Ekonol composites in different environments and proposed a method for selecting frictional materials incorporating operation conditions. Ding et al designed polyvinylidene fluoride and potassium titanate whisker reinforced polytetrafluoroethylene (PTW/PTFE) composites and found that such composites could improve the wear performance of USMs.…”

Section: Introductionmentioning

confidence: 99%

Friction and wear behavior of PI and PTFE composites for ultrasonic motors

Zhao

Zhang

et al. 2018

Polymers for Advanced Techs

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High-performance polymer-based frictional materials have become increasingly important to improve the mechanical output properties of ultrasonic motors. This study discussed the friction and wear behavior of 2 dominating frictional materials of polymer composites for ultrasonic motors, polyimide (PI), and polytetrafluoroethylene (PTFE) filled by aramid fibers (AF) and molybdenum disulfide (MoS 2 ). To explore the wear mechanisms, the tribo-pair contact stress was theoretically characterized, and the interface temperature rise was numerically predicted. The predictions showed that the flash temperature on asperity tips could reach the glass transition temperature of the polymer materials. The experimental results indicated that the contact stress and sliding speed have a small effect on the friction of the PI composite but influence considerably the friction of the PTFE composite. A higher contact stress brings about a higher specific wear rate, but a higher sliding speed reduces the wear rate. Compared with AF/MoS 2 /PTFE, the AF/MoS 2 /PI has much better tribological performance under high loads and speeds. KEYWORDS friction and wear, polyimide, polytetrafluoroethylene, temperature, ultrasonic motors 1 | INTRODUCTION An ultrasonic motor (USM) is driven by the frictional force between its stator and rotor. Such motors have been extensively used in medical apparatus, precision positioning devices, and aerospace structures because of their fast response capacity, high torque at low speed, and self-locking without the application of external power. 1 However, there are also drawbacks which have hindered the development of USMs, including their low transfer efficiency, poor mechanical output stability, and short service life in harsh environments. To improve the performance of USMs, better frictional materials of ultralow wear rate and stable friction are required because their properties determine directly the output characteristics and service life of USMs in complex, harsh environments. Some frictional materials have been tested for USMs, 2-6 including rubber, resin, metal coatings, alloys, and ceramic composites. It was found that most of them cannot meet the requirements due to, eg, severe wear, short service life, and high noise. Polymer-based frictional materials, however, have been found to be applicable to travelling wave USMs for their excellent wear resistance, low noise, suitable hardness, and thermal stability. For instance, Rehhein and Wallaschek 7 studied the friction and wear behavior of PI composites and found that the inclusion of carbon fibers could improve the wear resistance of PI sliding against steel. Ishii et al 8 established a method to predict the service life of USMs with a carbon-fiber-reinforced polymer as the frictional material. Qu et al 3-5,9,10 investigated the tribological properties of polytetrafluoroethylene (PTFE), phenolic resin, and Ekonol composites in different environments and proposed a method for selecting frictional materials incorporating operation conditions. Ding et al ...

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Micro‐Driving behavior of carbon‐fiber‐reinforced epoxy resin for standing‐wave ultrasonic motor

Cited by 17 publications

References 16 publications

Synthesis of poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate)reactive block copolymer with controlled reactivity for toughening multifunctional epoxy resin

Synthesis of poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate)reactive block copolymer with controlled reactivity for toughening multifunctional epoxy resin

Comparative study of tribological properties of insulated and conductive polyimide composites

Friction and wear behavior of PI and PTFE composites for ultrasonic motors

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