Synthesis Of Hyperbranched Polymer Containing Polysiloxane And Study On Heat Resistance Of Uncured Asphalt Waterproof Coating

Uncured rubber asphalt waterproof coating is a new type of waterproof coating developed in the past ten years.Its main components are rubber and asphalt,and it also contains various fillers such as tackifying resin,softening oil and additives.The addition of rubber and tackifying resin can make asphalt become a paste with good creep and viscosity at room temperature.Uncured rubber asphalt waterproof coating is widely used in non-exposed building waterproofing projects,and has the properties of waterproofing,bonding,sealing and grouting slurry.In order to obtain better creep performance and easy construction,the uncured rubber asphalt waterproof coating is usually designed to have greater fluidity under high temperature environment.In summer,the outdoor temperature can reach more than 50°C,and the surface temperature may be close to 80°C.The heat exchange between the uncured rubber asphalt waterproof coating after heating and melting and the environment becomes very slow,resulting in a very slow cooling rate of the uncured rubber asphalt waterproof coating.Therefore,during the construction process of uncured rubber asphalt waterproof coating,it is easy to flow and drip.These disadvantages limit the application of uncured rubber asphalt waterproof coating.Hyperbranched polymers can be simply described as highly branched polymers with three-dimensional network space structure,which contains a large number of active groups at its ends.Hyperbranched polymers have many special properties such as low viscosity,good film-forming properties and solubility.These characteristics make hyperbranched polymers widely used in medicine,energy,coatings,adhesives and other fields.Polysiloxane is a polymer whose molecular main chain is repeated Si-O bond,and other organic groups are connected to the silicon atom.The organic groups on the silicon atom are methyl,ethyl,phenyl,alkoxy and the like.Polysiloxane has many unique properties,such as excellent resistance to high and low temperatures,aging resistance,insulation,water repellency,and not easy to burn.At present,polysiloxane has been widely used in the fields of coatings,adhesives,thermal insulation materials,weather-resistant materials,insulating materials and waterproof materials.This article focuses on the synthesis and modification of hyperbranched polymers containing polysiloxane and their effects on the performance of uncured rubber asphalt waterproof coatings.The main contents are as follows:1.Synthesis and characterization of hyperbranched polyester amide（HBPEA）First,the succinic anhydride,maleic anhydride,and phthalic anhydride were reacted with trimethylolaminomethane respectively to prepare three AB₃ monomers;Then the AB₃ monomer is gradually polymerized at both ends of polydimethylsiloxane chain with hydroxypropyl terminal group to synthesize second-generation,third-generation and fourth-generation HBPEA.fourier transform infrared and ¹H nuclear magnetic resonance analysis proved that the AB₃ monomer and hyperbranched polymer had been successfully synthesized.In addition,the hydroxyl value analysis and elemental analysis of HBPEA also proved this conclusion from the side.The thermal stability analysis show that HBPEA has good thermal stability.2.Synthesis and characterization of modified hyperbranched polyester amide（mHBPEA）Methacrylic acid was used as a modifier to react with HBPEA to convert the terminal hydroxyl group into a double bond,and the structure of the product was characterized by fourier transform infrared and ¹H nuclear magnetic resonance.The results showed that methacrylic acid successfully reacted with HBPEA.In addition,the hydroxyl value of HBPEA is significantly reduced,which also indicates that the hydroxyl group on the surface of mHBPEA has reacted with methacrylic acid.3.Performance test of modified uncured rubber asphalt waterproof coatingMix HBPEA and mHBPEA with uncured rubber asphalt waterproof coating,and test the effect of two hyperbranched polymers on the performance of uncured rubber asphalt waterproof coating under different dosages.According to the standard JC/T 2428-2017"Uncured Rubber Asphalt Waterproof Coating",the heat resistance,low temperature flexibility and bonding strength of the modified uncured rubber asphalt waterproof coating were tested.The results are shown below:（1）With the increase of the content of hyperbranched polymers,the heat resistance of uncured rubber asphalt waterproof coatings has been improved to varying degrees,and the modification effect of hyperbranched polymers prepared with phthalic anhydride as the raw material is the most obvious.As the generation of hyperbranched polymers increases,the number of terminal active functional groups also increases,and the heat resistance of uncured rubber asphalt waterproof coatings also increases.（2）The bonding strength test results show that the bonding strength of the uncured rubber asphalt waterproof coating modified by HBPEA and mHBPEA has been greatly improved;when the addition amount is 7.5%,the modification effect of the two reaches maximum.（3）The low temperature flexibility test results show that the low temperature flexibility of the uncured rubber asphalt waterproof coating modified by HBPEA and mHBPEA has no cracks at-20°C.This shows that the low-temperature flexibility of the modified uncured rubber asphalt waterproof coating meets the product standard when the addition amount does not exceed 15%.