Relaxation in Physical and Mechanical Behavior of Polymers

Arzhakov, M. S.

doi:10.1201/9780429244520

Cited by 14 publications

(8 citation statements)

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“…This is likely due to the polymer chain relaxation phenomenon. 37 Figures 5, 6, and S7 also show that the maximum and minimum electrical resistances reduce slowly as the number of cycles increases. This is attributed to CNT− polymer chain interactions (supported by SEM and Raman spectroscopy; Figures S2 and S3), where during loading, PPR chains are strained into an entropically unstable condition following the mechanical deformation direction resulting in CNT rotation toward the stretching direction.…”

Section: ■ Results and Discussionmentioning

confidence: 78%

Synthesis and Characterization of Carbon Nanotube-Doped Thermoplastic Nanocomposites for the Additive Manufacturing of Self-Sensing Piezoresistive Materials

Verma

Ubaid

Varadarajan

et al. 2022

ACS Appl. Mater. Interfaces

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We present carbon nanotube (CNT)-reinforced polypropylene random copolymer (PPR) nanocomposites for the additive manufacturing of self-sensing piezoresistive materials via fused filament fabrication. The PPR/CNT feedstock filaments were synthesized through high shear-induced melt blending with controlled CNT loading up to 8 wt % to enable three-dimensional (3D) printing of nanoengineered PPR/CNT composites. The CNTs were found to enhance crystallinity (up to 6%) in PPRprinted parts, contributing to the overall CNT-reinforcement effect that increases both stiffness and strength (increases of 56% in modulus and 40% in strength at 8 wt % CNT loading). Due to electrical conductivity (∼10 −4 −10 −1 S/cm with CNT loading) imparted to the PPR by the CNT network, multifunctional in situ strain and damage sensing in 3D-printed CNT/PPR bulk composites and lattice structures are revealed. A useful range of gauge factors (k) is identified for strain sensing (k s = 10.1−17.4) and damage sensing (k d = 20−410) across the range of CNT loadings for the 0°print direction. Novel auxetic re-entrant and S-unit cell lattices are printed, with multifunctionality demonstrated as strain-and damage-sensing in tension. The PPR/CNT multifunctional nanocomposite lattices demonstrated here exhibit tunable strain and damage sensitivity and have application in biomedical engineering for the creation of self-sensing patient-specific devices such as orthopedic braces, where the ability to sense strain (and stress) can provide direct information for optimization of brace design/fit over the course of treatment.

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Section: ■ Results and Discussionmentioning

confidence: 78%

Synthesis and Characterization of Carbon Nanotube-Doped Thermoplastic Nanocomposites for the Additive Manufacturing of Self-Sensing Piezoresistive Materials

Verma

Ubaid

Varadarajan

et al. 2022

ACS Appl. Mater. Interfaces

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“…Splitting of the 1st diffraction peak can be interpreted based on a cluster model of polymers 46 . The notes of a physical grid are ordered clusters (in this case, they are constructed from segments of macrochains of the straightened conformation), which are characterized by an increased local order.…”

Section: Resultsmentioning

confidence: 99%

The impact of intense types of effects on poly(N‐vinyl caprolactam) and composites in the system nanoscale anatase – poly(N‐vinyl caprolactam)

Chikhacheva

Safyanova

Тимаева

et al. 2020

J of Applied Polymer Sci

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For the first time, the effects of microwave and ultrasonic treatments and an alternating electric field on poly(N‐vinyl caprolactam) (PVCL40) both in the original and in the composite with nanoscale anatase have been studied. Comparison of the results of studying the samples by X‐ray diffraction, IR spectroscopy, differential scanning calorimetry (DSC) before and after treatments allowed us to identify, and explain the response of objects to different types of effects with a change in their characteristics. Analysis and comparison of the results do not exclude the misorientation of the PVCL40 domains in thin films (microwave processing), which becomes flat‐ordered after their rubbing, the destruction of the PVCL40 and the disorder of the side substituent are found, accompanied by a change in the periodicity chains (microwave processing, electric field), a decrease in the water content in the system (microwave processing) and amorphization of nanoscale anatase (microwave processing, electric field) were revealed. The implementation of the revealed effects as response to microwave, ultrasonic, and electric field treatments on a similar type of polymers with a different composition and structure is not ruled out.

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“…Structures found due to this research process are globular or domain conglomerate structures, because the peripheric surface of domains has properties other than inner [ 10 , 11 ]. Inter-domain bonds are molecular, so they have less energy and are more moveable under load and heating [ 12 , 13 , 14 , 15 ]. The energy of dissipation or entropy can determine the energy of these bonds.…”

Section: Introductionmentioning

confidence: 99%

“…Inter-domain bonds are molecular, so they have less energy and are more moveable under load and heating [ 12 , 13 , 14 , 15 ]. The energy of dissipation or entropy can determine the energy of these bonds.…”

Section: Introductionmentioning

confidence: 99%

Prolonged Thermal Relaxation of the Thermosetting Polymers

et al. 2021

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The rigidity of structures made of polymer composite materials, operated at elevated temperatures, is mainly determined by the residual rigidity of the polymer binder (which is very sensitive to elevated temperatures); therefore, the study of ways to increase the rigidity of polymer materials under heating (including prolonged heating) is relevant. In the previous research, cured thermosetting polymer structure’s non-stability, especially under heating, is determined by its supra-molecular structure domain’s conglomerate character and the high entropy of such structures. The polymer elasticity modeling proved the significance of the entropy factor and layer (EPL) model application. The prolonged heating makes it possible to release adsorptive inter-layer bonds and volatile groups. As a result, the polymer structure is changing, and inner stress relaxation occurs due to this thermo-process, called thermo-relaxation. The present study suggests researching thermo-relaxation’s influence on polymers’ deformability under load and heating. The research results prove the significant polymer structure modification due to thermo-relaxation, with the polymer entropy parameter decreasing, the glassing onset temperature point (Tg) increasing by 1.3–1.7 times, and the modulus of elasticity under heating increasing by 1.5–2 times.

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Relaxation in Physical and Mechanical Behavior of Polymers

Cited by 14 publications

References 0 publications

Synthesis and Characterization of Carbon Nanotube-Doped Thermoplastic Nanocomposites for the Additive Manufacturing of Self-Sensing Piezoresistive Materials

Synthesis and Characterization of Carbon Nanotube-Doped Thermoplastic Nanocomposites for the Additive Manufacturing of Self-Sensing Piezoresistive Materials

The impact of intense types of effects on poly(N‐vinyl caprolactam) and composites in the system nanoscale anatase – poly(N‐vinyl caprolactam)

Prolonged Thermal Relaxation of the Thermosetting Polymers

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