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A magnesium (Mg)-rich primer can provide cathodic protection for an aluminum (Al) alloy due to the lower potential of Mg. However, the Mg-rich primer prepared by simple blends shows poor flexibility and impact resistance. In this paper, bisphenol-A type epoxy resin E-20 was graft modified by hydroxyl silicon oil (HS), amino silane coupling agent an...
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... The PDMS was included in the composition in order to improve the flexibility and impact resistance of the resultant coatings, as well as to improve compatibility of the polymer phase with magnesium. Interestingly, the reaction system allowed for both dehydration and etherification ( Figure 12) to take place, leading to graft and (multi) block copolymers, respectively, with the latter being the prevalent reaction, based on IR spectroscopic investigations [30]. Thiol-functionalised polysiloxanes were equipped with imidazolium-and pyrrolidinium-derived grafts using a "grafting to" approach [29]. ...
... The PDMS was included in the composition in order to improve the flexibility and impact resistance of the resultant coatings, as well as to improve compatibility of the polymer phase with magnesium. Interestingly, the reaction system allowed for both dehydration and etherification ( Figure 12) to take place, leading to graft and (multi) block copolymers, respectively, with the latter being the prevalent reaction, based on IR spectroscopic investigations [30]. Hydroxyl-terminated PDMS was also used alongside a bisphenol-A-type epoxy resin and magnesium powders to produce Mg-filled coatings, designed as materials for cathodic protection of aluminium alloy surfaces. ...
... The PDMS was included in the composition in order to improve the flexibility and impact resistance of the resultant coatings, as well as to improve compatibility of the polymer phase with magnesium. Interestingly, the reaction system allowed for both dehydration and etherification ( Figure 12) to take place, leading to graft and (multi) block copolymers, respectively, with the latter being the prevalent reaction, based on IR spectroscopic investigations [30]. A new graft copolymer was produced via the hydrosilylation reaction of a Si-H functionalised polysiloxane and allyl polyglycidyl ether. ...
Siloxanes are adaptable species that have found extensive applications as versatile materials for functionalising various surfaces and as building blocks for polymers and hybrid organic-inorganic systems. The primary goal of this review is to report on and briefly explain the most relevant recent developments related to siloxanes and their applications, particularly regarding surface modification and the synthesis of graft copolymers bearing siloxane or polysiloxane segments. The key strategies for both functionalisation and synthesis of siloxane-bearing polymers are highlighted, and the various trends in the development of siloxane-based materials and the intended directions of their applications are explored.
To improve thermal, mechanical and adhesion properties, epoxy resin was modified with methyl phenyl silicone (MPS), acrylonitrile butadiene styrene (ABS) and graphene oxide (GO). In order to increase compatibility and stability, MPS intermediate was grafted on epoxy resin through condensation reaction. Transmission electron microscopy images showed well dispersion of GO particles in the system proving successfully preparation of the MPS grafted epoxy/ABS/GO nanocomposite. Single lap shear strength for steel-epoxy/carbon fiber composite joint in sample containing 15% MPS and 2% ABS improved up to 108% compared to neat epoxy. Such an improvement occurred when only 5% MPS, 2% ABS and 0.1% GO were used showing GO could decrease required content of modifiers in this case. Tensile strength of sample containing 5% MPS and 2% ABS was 49.89 MPa and it reached 55.23 MPa by adding 0.1% GO while it was 37.12 MPa in pure epoxy. Nanocomposite modified sample had a residual char of 20 wt%. at 600°C and increment of 30°C in initial degradation temperature and 7°C in maximum degradation temperature compared to pure epoxy. These finding beside 23% increasing in calculated activation energy using Kessinger's and FWO method's proved significantly improved thermal stability of modified epoxy resin. Scanning electron microscope images of fractured surface of specimens showed micro size domains obtained by phase separation cause toughness improvement and crack energy absorption.
Magnesium (Mg)-rich primer is considered as a substitute for high polluted chromate treatment technology to provide cathodic protection for aluminum (Al) alloy. In this paper, Mg-rich primer with comprehensive properties was prepared by modifying epoxy resin using direct mixing. Specifically, the influence factors on the dispersion of Mg powder in epoxy, the modification of epoxy resin using organic silicones and the performance of Mg-modified epoxy composite coating were studied. The results show that Mg powder with small particle size has a better dispersion in epoxy; The mechanical property such as flexibility and impact resistance decreases with the addition of Mg powder, but which was improved when using modified epoxy as the resin matrix due to introduction of Si-O-Si flexible chain; In addition, the grafting efficiency between hydroxyl terminated polydimethylsiloxane and epoxy resin was improved because of the introduced silane coupling agent like KH550 contains amino group; The electrochemical test results indicate Mg-rich primer could provide effective electrochemical protection for Al alloy by raising the corrosion potential and reducing the corrosion current density to bare substrate,respectively.
Preparation of silicon-containing epoxy composites with unique properties using silanes, siloxanes, silica, and polyhedral oligomeric silsesquioxanes (POSSs) was considered. Analysis shows that oligomeric and polymeric siloxanes with terminal and internal reactive functional groups are promising for decreasing the surface energy, increasing the contact angle with water, and enhancing the elasticity, heat resistance, and anticorrosive and antifouling properties of the coatings. It is appropriate to use organosilicon adhesion promoters with various functional groups in multilayer coating systems for enhancing the interlayer adhesion, improving the compatibility of (nano)microfillers with the polymer matrix, and thus making the coatings more durable. This opens wide possibilities for using silicon-containing composites of new generation in the technology of anticorrosive and antifouling coatings and also as electronics materials, materials with decreased flammability, semipermeable membranes, spacecraft coatings, etc.
