“…As the catalyst increased to a certain dosage, the substrate concentration was constant and the increased active site of the catalyst was not combined with sufficient reactants. Its time change slowed down . Insufficient dosage of catalyst may lead to a long reaction time, which was not in favor of the later chain extending reaction due to inappropriate resulted viscosity.…”
“…As the catalyst increased to a certain dosage, the substrate concentration was constant and the increased active site of the catalyst was not combined with sufficient reactants. Its time change slowed down . Insufficient dosage of catalyst may lead to a long reaction time, which was not in favor of the later chain extending reaction due to inappropriate resulted viscosity.…”
“…These factors are known as cell identification and varied linearly by cell size variation. 62,63 Figure 4.PU microstructural parameters in the SEM image. 61 …”
Offshore pipelines are vulnerable against erosion/wear deterioration mechanisms that can be controlled through the use of proper surface coatings, such as polymer matrix nano-composite (PMNC) coatings that are well-known for their ease of production, availability and applicability. Epoxy, as a versatile rigid and brittle resin and polyurethane with proper chemical/mechanical properties, are potential candidates to make the matrix of these composites. A combination of these polymers can also enhance the mechanical behaviors, glass transition temperature and flexibility. In addition, the desired coating characteristics, such as adhesion to metal substrate, mechanical properties, erosion/wear resistivity and UV absorbance, can be further improved through the addition of appropriate nanoparticles within the polymer matrix. Especially, nanoparticles can improve the erosion/wear resistance of polymers because of establishing high strength bonds between the polymer chains and the reinforcements besides enhancing other required properties. The present work is a review on PMNC coatings that contain epoxy, polyurethane or EP/polyurethane as a polymer matrix along with the details of the nanoparticle reinforcements, such as alumina, silica, titanium oxide, zinc oxide, clay and carbon-based materials. The effect of these nanoparticles on the properties of composite coatings has also been investigated.
“…1, the smallest size of PDMS spheres inside the bicontinuous structure leads to the highest interfacial contact by increasing the number of spheres. Considering the research involving the increase in interphase compatibility between TPU and PDMS, [41][42][43] one may expect that the introduction of some compatibilizer could either, reduce the content of PDMS to create the bicontinuous phase, or the size of the PDMS spheres. Thus, addition of a compatibilizer could increase the interfacial contact between TPU and PDMS at a given content, inducing higher electromechanical strain comparing to the current system without any compatibilizer.…”
Herein we report the highly improved electromechanical actuation of thermoplastic polyurethane (TPU) by blending with polydimethylsiloxane (PDMS) to construct a bicontinuous structure. TPU/PDMS blend films with various PDMS loadings were fabricated through a simple solution-assisted casting method. Infrared spectroscopy measurements confirmed that TPU and PDMS are thermodynamically incompatible with each other. For TPU 80 with 80 parts of PDMS, a bicontinuous phase structure was achieved. The TPU 80 film showed greatly decreased elastic modulus and improved elongation at break compared to pristine TPU. It also showed the highest dielectric constant among the TPU/PDMS blend films with various contents of PDMS due to strong interfacial polarization. Most importantly, the TPU 80 film exhibited a maximum areal strain of 2.3% under an electric field of 40 V mm À1 , which is about 60 times higher than that of pristine TPU. The results described in this work demonstrate that the construction of a bicontinuous interface structure at the micrometer scale is very effective to develop elastomers with superior electromechanical actuation performance.
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