A self-healing supramolecular polymer composite (LP-GO) is designed and prepared via incorporation of graphene oxide (GO) to hyperbranched polymer by hydrogen-bonding interactions. The polymer matrix based on amino-terminated hyperbranched polymer is synthesized by dimer acid and diethylene triamine, while GO is prepared by the modified Hummers method. Infrared spectroscopy (FTIR), thermo gravimetric testing (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) is applied to characterize GO. Stressstrain test is utilized to characterize the obtained self-healing property of LP-GO. It is found that just a small amount of GO (up to 3 wt %) is needed to achieve a dramatic improvement in the mechanical properties, and self-healing efficiency of the polymer composites. After healing at o 60 C for 1 h, the addition of GO even restores the self-healing efficiency to 100% of its original tensile strength. In striking contrast to conventional cross-linked or thermoreversible rubbers made of macromolecules, these systems, when being broken or cut, can be simply healed by contacting fractured areas again to self-heal at suitable temperature. Building on the unique self-healing properties, the simplicity of synthesis and the availability from renewable resources, etc., LP-GO bodes well for broader applications in the near future.
Ti3SiC2, a ternary carbide, was proposed at this paper to use as the binder of polycrystalline diamonds to overcome the weaknesses of traditional metal binders and ceramic binders. Ti3SiC2was first reported to be in-situ synthesized under high pressure (4GPa) and at high temperature (1400°C) (HPHT) from the mixtures of Ti, Si and graphite powders or the mixture of Ti, SiC and graphite powders. Ti3SiC2-damond composites were also made at HPHT from the previous mixtures and diamond particles. TiCx, Ti5Si3Cxand TiSi2were main impurities and/or intermediate products of Ti3SiC2samples synthesized at HPHT. Ti3SiC2content increased as synthesized time increased from 10 min to 60 min. For as-synthesized composites, diamond particles were evenly distributed in matrix. The diamond particles are bonded well with the matrix by three types of interface.
With adopting Al as the nitrogen getter in Ni70Mn25Co5 or Fe55Ni29Co16 catalyst, High-quality type-Ⅱa large diamonds have been grown under the conditions of about 5.5GPa and 1580K by using the temperature gradient method. While Al(2.0wt%) is added in the Fe55Ni29Co16, the nitrogen concentration(Nc) in the diamond is less than 1ppm. While Al(4.0wt%) is added in the Ni70Mn25Co5, the Nc in the diamond is highly arrived at 48ppm. The different of solubility of nitrogen in both catalyst at high pressure and high temperature is the basic reason of the different effect of eliminating nitrogen of Al. It can be shown in experamentals that Al is a less efficient nitrogen getter in Ni70Mn25Co5 than in Fe55Ni29Co16. While Al(2.0wt%) is added in the Fe55Ni29Co16, the high-quality type-Ⅱa large diamond, in which nitrogen is less than 1ppm and which the size was arrived at 3.3mm, had grown by decreasing the growth rate of diamond.
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