The current study focuses on giving a basic understanding of tubular graphene sheets or carbon nanotubes (CNTs) and points towards their role in fabricating elastomer composites. Since the properties and the performance of CNT reinforced elastomer composites predominantly depend on the rate of dispersion of fillers in the matrix, the physical and chemical interaction of polymer chains with the nanotubes, crosslinking chemistry of rubbers and the orientation of the tubes within the matrix, here, a thorough study of these topics is carried out. For this, various techniques of composite manufacturing such as pulverization, heterocoagulation, freeze drying, etc. are discussed by emphasizing the dispersion and alignment of CNTs in elastomers. The importance of the functionalization technique as well as the confinement effect of nanotubes in elastomer media is derived. In a word, this article is aimed exclusively at addressing the prevailing problems related to the CNT dispersion in various rubber matrices, the solutions to produce advanced high-performance elastomeric composites and various fields of applications of such composites, especially electronics. Special attention has also been given to the non-linear viscoelasticity effects of elastomers such as the Payne effect, Mullin's effect and hysteresis in regulating the composite properties. Moreover, the current challenges and opportunities for efficiently translating the extraordinary electrical properties of CNTs to rubbery matrices are also dealt with.

Carbon nanotube based elastomer composites – an approach towards multifunctional materials

Piezoresistivity, Strain, and Damage Self-Sensing of Polymer Composites Filled with Carbon Nanostructures

Transport performance in novel elastomer nanocomposites: Mechanism, design and control

Shape memory polymers (SMPs) based on fully biobased poly(lactide) (PLA)/natural rubber (NR) thermoplastic vulcanizates (TPVs) were fabricated via peroxide-induced dynamic vulcanization. Simultaneously, in situ reactive compatibilization was achieved by PLA molecule grafting onto NR chains. Differing from the general concept of spherical rubber particles being formed after dynamic vulcanization, the cross-linked NR was found to be a “netlike” continuous phase in the PLA matrix. This novel structure explained the surprising shape memory property of PLA/NR TPVs well (shape fixities ∼ 100%, shape recoveries > 95%, and fast recovery speed < 15 s at the switching temperature, ∼60 °C): the cross-linked NR continuous phase offers strong resilience and the PLA phase serves as the heat-control switch. We envision that the “green” raw materials and excellent shape memory properties of the dynamically vulcanized PLA/NR SMPs will open up a wide range of potential applications in intelligent medical devices.

Fully Biobased Shape Memory Material Based on Novel Cocontinuous Structure in Poly(Lactic Acid)/Natural Rubber TPVs Fabricated via Peroxide-Induced Dynamic Vulcanization and in Situ Interfacial Compatibilization

This paper presents the development process for a new kind of compliant piezoresistive transducer based on carbon-nanotube-filled silicone rubber composite. The methods for the composite fabrication and the sensor probe encapsulation are specified. The piezoresistive mechanism of the composite is researched based on the tunneling effect theory. The calibration and transforming method is designed based on the piezoresistivity of the composite. The signal processing system is developed to realize the data conversion, acquisition, processing, and pressure displaying. The transducer system is tested within the measurement range from 0 to 2 MPa at room temperature. The measuring error is 4% full scale. The transducer system can be used to measure the interlaminar pressure of the industrial equipment. Its key technologies can also be used to fabricate an electronic skin and a robotic haptic sensing system.

http://cms.kdis.edu.cn/csceng_neu/monographs/Academicpaper/resource/2d4906659a8880037b72dc5c631adc5c.pdf

A Review for Conductive Polymer Piezoresistive Composites and a Development of a Compliant Pressure Transducer

Conducting rubber composites of ethylene propylene diene M-class rubber (EPDM) were prepared with multi walled carbon nanotubes (MWCNTs) and organo-clay, Cloisite® 15A to develop flexible strain sensitive materials. The composites were prepared with a constant amount of organo-clay and various amounts of MWCNTs from 5 to 50 wt.%. Organo-clay led to improved dispersion of MWCNTs in the rubber matrix. Upon increasing the MWCNT contents, the tensile strength, stiffness and electrical conductivity of the composites increased significantly but the elongation at break decreased in the EPDM/MWCNT composites. The organo-clay was able to improve tensile strength, stiffness, elongation at break and electrical conductivity of the composites. The non-symmetric linear resistance change was observed by the composites under deformation.

Pil Jung Yoon

Papers

Preparation and properties of ethylene propylene diene rubber/multi walled carbon nanotube composites for strain sensitive materials