Research On Synthesis Of Series Of Styrene-Acrylic Latex And Toughness Of Their Modified Mortar

Mortar is a multi-phase multi-component cement-based material,and its brittleness restricts its own advantages such as good durability and high compressive strength.adding polymer latex as an effective method to toughen mortar,it has always been concerned by researchers in the field,but the related research on its toughening mechanism and structure-activity relationship is still immature.this research starts from a complete route such as the synthesis and analysis of polymer latex,the preparation of modified mortars,and the characterization of mortar properties,and focuses on the relationship between the polymer composition and the properties of the latex film and the toughness of the modified mortar.the main research content and research results include:Five groups of styrene-acrylic(SA)latex with different ratios of soft and hard monomers were synthesized by pre-emulsified semi-continuous seeded emulsion polymerization,and Some of their properties such as the particle size,micro morphology,glass transition temperature(Tg)and minimum film forming temperature(MFFT)of different latex particles were characterized and analyzed.the relationship between latex particle composition,latex film damping properties,latex film adhesion properties and latex dosage with the ratio of compressive strength to flexural strength,fracture energy and fracture toughness of modified mortars in different ages were studied.the results show that the damping properties of the latex film is significantly affected by the ratio of soft and hard monomers in the SA latex,the damping properties of the latex film are consistent with the fracture energy of the modified mortar,the maximum value was 211.2N/m,which was 2.4 times that of blank group.but there is no significant correlation between the latex composition,the properties of the latex film with their modified mortar.The SA latex was modified with SMA which is a long-chain structure,and the fracture performance of the mortar with different emulsion dosages and different ages was investigated.the results show that after the modified with SMA,the damping temperature range of the latex film moved to low temperature,its damping loss factor at normal temperature decreased,and the fracture energy of the corresponding modified mortar also decreased.The positive correlation between the damping properties of the latex film with the fracture energy of their modified mortar was further verified.The SA latex with the highest fracture energy of modified mortar was compared with styrene-butadiene latex(SBR)and polyethylene-vinyl acetate(EVA)rubber powder.the difference between the fracture parameters of the modified mortar,such as the ratio of compressive strength to flexural strength,fracture energy and fracture toughness,was investigated.the results show that for the fracture energy,SBR will slightly reduce the fracture energy of the mortar,and EVA has no significant increase in the fracture energy of the mortar.in addition,for SA latex and EVA,there is still a positive correlation between the damping properties of the latex film and the fracture energy of the modified mortar,but SBR does not satisfy the relationship;for the ratio of compressive strength to flexural strength,SA modified mortar is the highest,EVA modified mortar is the second,and SBR modified mortar is the lowest;but compared with the fracture toughness,EVA modified mortar is the highest,SBR modified mortar is the second,and SA modified mortar is the lowest.