Preparation Of Polyolefin Polyurethane Coatings And Their Antifouling And Anti-cavitation Erosion Performance

Marine organism fouling caused by the adhesion of fouling organisms and cavitation corrosion on the surface of sea-immersed materials has become a key and difficult problem in the field of marine material protection technology.However,the development of materials that are suitable for the marine environment and have good anti-fouling and anti-cavitation capabilities are still facing huge challenges.Polyurethane elastomer material has become a potential anti-cavitation material due to its excellent mechanical properties,high elasticity,good structural designability,and the characteristics of acid resistance,alkali resistance,weather resistance,and good abrasion resistance.However,the poor water resistance and weak antifouling propertie of polyurethane materials still limit its further application.Therefore,this thesis proposes a research idea of introducing fillers and functional segments into polyurethane matrix materials to improve the comprehensive performance of polyurethane materials from the two research perspectives of micro-nano functional filler doping and polymer segment structure design,and five kinds of polyurethane-based anti-cavitation and antifouling coatings were prepared based on this idea.The polyurethane clove oil antifouling microcapsules(CMO)were prepared by interface and in-situ polymerization technology using natural plant extract clove oil as the antifouling component,and a series of polyurethane coating(PCMOH)with antifouling and anti-cavitationerosion resistance properties were prepared by blending the microcapsules as the filler.The secondary deposition of the CMO microcapsule shell improves the mechanical properties of the microcapsule,and adjust the clove oil release ability of the PCMOH series coating,in addition,the antifouling ability of the PCMOH coating also can be adjusted by controlling the deposition time.The antifouling ability test of the PCMOH series coatings shows that the antifouling ability of the PCMOH coating is proportional to the release rate of clove oil.The PCMOH1 and PCMOH2 coatings obtained outstanding anti-algae adhesion abilities by adding microcapsules which has 15 and 30 min secondary deposition time;Combining the environmental friendliness and the results of the actual sea test,the PCMOH2 coating has the best comprehensive antifouling ability,but the long-term antifouling performance needs to be further improved.The cavitation corrosion resistance of the PCMOH series coatings has not been strengthened simultaneously,and the cumulative mass loss of the PCMOH1 coating with the best cavitation corrosion resistance for 30 hours of continuous cavitation erosion is 8.9 mg.In order to solve the problem of unsimultaneous improvement of the antifouling and anti-cavitation ability of the coating by the anti-fouling microcapsules,this paper chooses Fe₃O₄nanoparticles(FN)as the basic nano-filler,due to its low-cost,non-toxic,environmentally friendly and certain antifouling ability.FN and antifouling functionalized Fe₃O₄ nanoparticles(FPN)modified by phytic acid were synthesized by the hydrothermal method.Two composite coatings which named FN-PU and FPN-PU were constructed by nanocomposite method using PU elastomer as matrix resin,and a series of basic structure and performance characterization of FN-PU and FPN-PU composite coatings were carried out to explore the influence of FN nanoparticles and post-functionalized FPN nanoparticles on coating performance.Subsequently,the results of the anti-algae adhesion test and the real sea static suspension test both show that FPN-PU has a good antifouling ability.The FPN nanoparticles have successfully enhanced the antifouling ability of the polyurethane coating.However,the results of the anti-cavitation test showed that the anti-cavitation ability of FPN-PU coating decreased due to the introduction of incompatible antifouling active ingredients.The cumulative mass loss of FN-PU after 30 hours of cavitation is 5.4 mg,which is significantly lower than FPN-PU coating(13.3 mg).A series PHZ composite anti-fouling and anti-cavitation coatings were prepared using multi-scale ZIF-8 with anti-biological activity as functional nano-filler,and the influence of ZIF-8 nano-fillers of different sizes on the structure and performance of the coating was studied.The basic structure,thermal stability and mechanical properties of the PHZ composite coating were systematically investigated.ZIF-8 NP can form a?bond between the segments of the PU matrix to form a stable whole to enhance the performance of PHZ composites,the small particle size ZIF-8 NP-Z1 has the most obvious enhancement on the PU matrix,the initial decomposition temperature of the PHZ1 coating has increased by 43?.At the same time the ultimate tensile strength increased to 6.78 MPa.The anti-algae adhesion test shows that the PHZ1 coating has the best antifouling performance among PHZ composits coatings,and the algae adhesion area is only 0.51%.The PHZ1 coating retains the excellent cavitation resistance of the original PU coating,and the cumulative mass loss of the PHZ1 coating is 9.9 mg after 30hours of cavitation exposure.The results show that the PHZ1 coating with nearly 50 nm ZIF-8NP is more suitable for practical applications.A series of fluorosilicated antifouling and cavitation resistant polyurethane coating SFPU-x(x=0,2,5 and 8)with a heterogeneous surface microstructure is prepared by introducing a fluorine-containing segment whcih is thermodynamically incompatible with the polyurethane(PU)matrix,the heterogeneous surface microstructure was induced by the microphase separation mechanism.The basic structure and performance of the SFPU-x coating were characterized.The influence of the heterogeneous microstructure on the anti-adhesion performance of the SFPU-x series coating was exploredthrough a series of anti-algae and anti-protein adhesion experiments.The protein and seaweed coverage on the surface of the SFPU-5 coating that has the most obvious heterogeneous microstructure is only 1.1%and 1.5%.Further real sea tests also show that the SFPU-5 coating has good practical application potential.The simulated cavitation test proves that the heterogeneous microstructure with higher hardness helps to improve the cavitation resistance.The cumulative mass loss of the SFPU-5 coating in deionized water and artificial seawater for 30 hours of cavitation erosion is only 5.8 and 6.3 mg.The research results prove that the heterogeneous microstructure can effectively improve the anti-fouling and anti-cavitation ability of the coating.PGH with guanidine group and PGHPA with both guanidine and phosphate groups were synthesized by melt polymerization method,using guanidine and phosphate groups as antifouling active ingredients and phytic acid as the donor of phosphate group.The PGH-PU coating and the PGHPA-PU anti-cavitation PU antifouling coating with long-term antifouling ability have been uccessfully prepared by the designability of PU segment structure.A series of basic characterizations for the two composite coatings were carried out to explore the influence of guanidine and phosphate groups on the performance of the coatings.After introducing guanidine and phosphate ester groups,the PGHPA-PU coating reveals excellent antifouling ability.The results of anti-seaweed and mussel adhesion experiments of the PGHPA-PU composite coating confirm great anti-seaweed adhesion ability and avoidance effect for mussels.Combined with the results of environmentally friendly and marine field tests,PGHPA-PU coating exhibits outstanding practical application potential.Promising cavitation resistance results of PGH-PU and PGHPA-PU coatings are performed from the anti-cavitation test with only 4.7 and 3.5 mg cumulative mass losses,respectively,after 30 hours of cavitation.The cavitation resistance of the PGH-PU coating benefits from its excellent mechanical properties,while that of the PGHPA-PU coating comes from the combined effect of its mechanical properties and the hydration layer.