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Energy system components with embedded sensors, or smart parts, can be a pathway in obtaining real-time system performance feedback and in situ monitoring during operation. Traditional surface contact or cavity placed sensors increase the possibility of disturbing the normal operation of energy systems due to changes in part design required for sensor placement. The fabrication of smart parts using additive manufacturing (AM) technology can allow the flexibility of embedding a sensor within a structure without compromising the structure and/or functionality. The embedding of a sensor within a desired location allows an end user the ability to monitor specific critical regions that are of interests such as high temperature and pressure (e.g. combustor inlet conditions that can reach up to 810K and 2760kPa). In addition, the nonintrusive placement of the sensor within a part's body can increase the sensor's life span by isolating the sensor from the aforementioned harsh operating environments. This paper focuses on the fabrication of smart parts using electron beam melting (EBM) AM technology as well as the characterization of the sensor's functionality. The development of a "stop and go" process was explored that comprised of pausing a part's fabrication process to allow the placement of piezoelectric ceramic material into pre-designed cavities within a part's body, and resuming the process to complete the final product. A compression test was performed on the smart parts fabricated using EBM to demonstrate the sensor's capability of sensing external forces. A maximum sensing voltage response of approximately 3V was detected with a maximum pressure not exceeding 40MPa. The sensor responses showed good agreement with the applied force in four different frequency conditions (i.e., 10Hz, 15Hz, 20Hz, and 25Hz). This research work demonstrates the feasibility of fabricating smart parts with embedded sensors without the need of post-processing (e.g., CNC machining and polishing). In addition, the sensing capability of monitoring a component's performance has been validated, leading to the possibility of fabricating other smart parts that could impact industries such as energy, aerospace, automotive, and biomedical industries for applications like air/fuel pre-mixing, pressure tubes, and turbine blades.

The incorporation of viscoelastic materials represents an effective strategy to reduce the vibratory level of structural components. Thermoplastic vulcanizates (TPVs) are a special type of viscoelastic material that combines the elastomeric properties of rubbers with the easy processing of thermoplastics. In the present work, we propose innovative ways to improve the damping properties of high-performance TPVs by using rubbers with carboxylic functionalities. For that, TPVs from physical blends of carboxylated hydrogenated acrylonitrile butadiene rubber (XHNBR) and polyamide 6 (PA6) were prepared. The chain dynamics of different mixed crosslink systems containing peroxide, metal oxides and hindered phenolic antioxidants were investigated in order to find the most suitable strategy to design a high-performance TPV system with upgraded damping properties. The results indicate that the damping performance of the TPV system can be tailored by controlling the type and magnitude of the bonding interactions between the mixed crosslink system and the XHNBR rubber phase. Therefore, this study demonstrates the potential of TPV systems containing carboxylic rubbers as high-performance damping materials.

Dynamic mechanical measurements have been used to study the a-and 8-relaxation in blends of Phenoxy (PH) and poly(e-caprolactone (PCL). Single glass transition temperatures between those of the original polymers are obtained. The crystallinity causes a significant influence on the Tt values, giving rise to a positive deviation from the Tt data obtained from DSC measurements. Regarding the 8-relaxation, it is observed that the two polymers relax independently of each other in the blend, although the shift of the Phenoxy 8-relaxation to lower temperatures as PCL concentration increases is a symptom of the influence of this polymer on the secondary relaxation of Phenoxy. We discuss this influence by comparing the Phenoxy 8-relaxations of PH/PCL blends with those of acetylated Phenoxy, PH/PEO blends, and antiplasticized Phenoxy and analyzing the effect of hydrogen-bonding interactions in the rotation of the hydroxy ether groups of Phenoxy.

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With the aim of curbing air pollution and addressing climate change, the use of low density thermoplastic elastomers (TPEs) in transportation could be a useful way to lighten the vehicle weight. For that, melt blending of high performance rubber and thermoplastics is an attractive way of preparing high performance TPEs. In this work, several TPEs have been prepared by melt blending of hydrogenated acrylonitrile butadiene rubber (HNBR) with polyamide 6 (PA6), adding different amounts of carboxylated HNBR (XHNBR) as compatibilizer: 40/60/0, 40/42/18, 40/30/30 and 40/18/42 (PA6/HNBR/XHNBR). The resulting blends were investigated using melt rheological measurements, morphological observations (scanning electron microscopy and polarized optical microscopy), dynamic mechanical analysis, differential scanning calorimetry analysis and mechanical tests. A biphasic morphology was noted for all TPEs. An increase in XHNBR amount changes the morphology from dispersed to co-continuous. This evolution is explained by the change in the melt rheological properties of the HNBR/XHNBR rubber phase. Moreover, the introduction of 42% XHNBR resulted in an increase in the glass transition temperature of both rubber and PA6 phases. This double T g increase phenomenon was attributed to the interfacial interactions between the carboxyl groups in XHNBR and the amine end groups in PA6. Additionally, thermal analysis revealed a reduced crystallinity of PA6 in the blend, which corresponds to enhanced interfacial interactions. The interfacial adhesion and the co-continuous morphology resulted in an improved ductility. This study reveals the possibility of obtaining TPE blends with tunable thermal and mechanical properties by controlling both interfacial interactions and morphology.

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