【摘要】 以木薯淀粉为原料、丙烯酸为接枝单体、过硫酸铵为引发剂，在固相体系中合成丙烯酸接枝淀粉，以水泥净浆流动度为评价指标，通过单因素实验得到最佳合成工艺参数为：单体用量(占淀粉干基质量分数)43%,引发剂用量(占淀粉干基质量分数)20%,反应温度60℃,反应时间3 h。FTIR、XRD、SEM结果表明木薯淀粉成功接枝上丙烯酸，淀粉接枝率为40%,接枝效率为74%。在水泥净浆、水泥砂浆和混凝土中添加0.6%(质量分数)的丙烯酸接枝淀粉时，水泥净浆流动度达到220 mm,凝结时间由330 min延长至910 min;水泥砂浆减水率为18.6%,水泥砂浆28 d的抗压强度由46.7 MPa增强至51.9 MPa;混凝土减水率达到17.9%,7 d的抗压强度达到33.8 MPa。丙烯酸接枝淀粉具有明显的缓凝减水作用，同时增强水泥的抗压强度，并延缓水泥初期水化反应速度，使水泥结构更加紧凑致密。更多还原

【Abstract】 By using cassava starch as raw material, acrylic acid as graft monomer and ammonium persulfate as initiator, acrylic acid grafted starch was synthesized in solid phase system. Based on fluidity of cement paste as the evaluation index, the optimal conditions for preparing acrylic acid grafted starch by single factor experiment are as follow: the amount of monomer(accounting for the mass fraction of starch dry basis) 43 wt%, the amount of initiator(accounting for the mass fraction of starch dry basis) 20 wt%, reaction temperature 60 ℃ and reaction time 3 h. Results of Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) and scanning electron microscope(SEM) indicated that acrylic acid groups had been introduced into starch molecules successfully where the graft ratio of acrylic acid grafted starch was 40% and the grafting efficiency was 74%. When 0.6 wt% acrylic acid grafted starch was added to the cement paste, cement mortar and concrete, the fluidity of cement paste reached 220 mm, with the coagulation time extending from 330 min to 910 min; the water-reducing rate of cement mortar was 18.6%, with the compressive strength(28 d) increasing from 46.7 MPa to 51.9 MPa; the water-reducing rate of concrete reached 17.9%, while the compressive strength(7 d) reached 33.8 MPa. Therefore, the acrylic acid grafted starch has significant water-reducing and retarding effects, and can enhance the compressive strength and delay the speed of the initial hydration reaction of cement, thus contributing to a more compact cement structure.更多还原