SAP内养护混凝土抗冻性能研究进展

综述了近几年国内外超吸水性树脂(SAP)应用于内养护混凝土抗冻方面的研究进展。介绍了SAP种类及在混凝土中的应用现状,阐述了SAP合成方法、吸释水原理、额外引水量设计方案,探讨了SAP粒径、掺量、合成方法及额外引水量等因素对混凝土抗冻性能的影响。总结了SAP内养护混凝土的研究要点,并展望了SAP内养护混凝土在高寒高海拔地区的研究方向,包括开发适用于特种环境下的SAP材料、建立不同环境下的额外引水量模型、掺杂自愈合生物菌落等。     

高吸水性树脂对超高性能混凝土性能的影响

本试验研究了不同种类SAP的使用对UHPC流动性、强度及自收缩的影响.试验结果表明,SAP的使用使UHPC流动度降低,流动度损失减缓;同时,如果选择适当粒径、掺量及吸水量的SAP,其掺入不会降低UHPC的抗压强度和抗折强度;另一方面,使用SAP后,UHPC的28 d自收缩明显降低,SAP是一种较理想的内部自养护材料.     

MBS树脂（M-338）的合成和应用

研究了影响丁苯胶乳粒径大小的主要因素,其中包括乳化剂、电解质、固含量及单体加入方式,实现了一步法合成粒径200～300nm的丁苯乳胶。以该胶乳接枝苯乙烯和甲基丙烯酸甲酯共聚单体合成甲苯丙烯酸甲酯/丁二烯/苯乙烯共聚物（MBS）树脂M-338,并研究了MBS微观形态及其改性硬PVC性能的影响因素。     

基于体视学的SAP混凝土气孔结构分析与研究

为了研究混凝土在添加高吸水性树脂后其内部气孔结构的变化规律,以及内部气孔结构的变化对混凝土试样抗压强度的影响,基于定量体视学的电子显微图像分析方法,对添加SAP混凝土的内部气孔结构特征展开了相关试验研究.采用干拌的方法拌和SAP混凝土,对不同配合比和不同SAP掺量的混凝土进行分批试验,测定出各组试样的气孔结构参数和抗压强度等,以深层次的剖析SAP对混凝土强度和内部气孔结构的影响.研究结果表明:混凝土内部气孔的平均孔径与间距系数随着SAP含量和水灰比的增加而增大,而混凝土抗压强度则呈现出相反的变化趋势.在配合比相同的情况下,小粒径SAP颗粒对混凝土气孔率的提高效果更为明显,而大粒径SAP颗粒对混凝土气孔平均孔径的提高效果更为明显;水灰比对气孔平均间距系数影响显著,而SAP粒径对混凝土内部气孔平均间距系数的影响不明显.     

自养护路面混凝土抗盐冻性能及疲劳特性

为有效增强路面混凝土耐久性能,基于盐冻试验、盐冻前后的断裂性能试验及弯拉荷载疲劳试验,探索了高吸水性聚合物(SAP)自养护路面混凝土抗盐冻性能及疲劳特性随SAP掺量、粒径的变化规律,并结合自养护水泥浆体孔隙参数、微观形貌及骨料-水泥石界面过渡区(ITZ)特征,揭示了性能影响机理。结果表明:小粒径SAP形成的残留孔洞能有效释放拉应力,降低结冰点,细化孔结构,从而增强路面混凝土抗盐冻性能;当SAP粒径为100目(150 μm),掺量为0.145%(质量分数)时,路面混凝土在冻融30次时的断裂韧度损失率、断裂能损失率分别比基准组降低了25.25%、10.51%;小粒径SAP对疲劳寿命的提升程度随应力水平的提高而增大,当应力水平为0.80时,自养护组的疲劳寿命相比基准组提升了2.65倍;SAP能够有效提升水泥混凝土结构内部密实度,吸持ITZ区域部分水分,增强水泥石和骨料之间的粘结性,从而改善混凝土抗盐冻性能和疲劳特性。     

自蔓延高温技术制备ZrC粉体(英文)

采用自蔓延高温合成(self-propagating high-temperature synthesis,SHS)技术,以 Zr+C 为反应体系合成了 ZrC 粉末。研究了实验参数对 SHS过程中点火电流、燃烧温度的影响。采用了 3 种碳源,研究了其对最终产物形貌及化学组成的影响。通过添加不同含量的 NaCl 作为 SHS 稀释剂,控制产物粒径及形貌。结果表明:炭黑是高温自蔓延法制备 ZrC 粉体的最佳碳源。由该体系制备的 ZrC 粉末粒径在 0.5～1 μm之间,氧含量为 0.38%。随稀释剂 NaCl 含量增加,体系燃烧温度降低,产物粒径减小。当 NaCl 含量为 30% (质量分数)时,体系燃烧温度下降至 1 810 K,产物 ZrC 粉末的粒径减小至 50 nm。     

聚丙烯酸酯微乳液平均粒径影响因素的研究

探讨了利用预乳化种子法合成聚丙烯酸酯微乳液的聚合过程中,去离子水用量、阴离子与非离子乳化剂配比及用量、聚合温度、功能性单体用量及混合单体配比对平均粒径的影响.结果表明,在反应过程中,控制去离子水用量为总质量的60%、乳化剂十二烷基硫酸钠(SDS)和壬基酚聚氧乙烯醚(OP-10)质量比为4:1及复合乳化剂的用量为总质量的3%～5%时,合成的微乳液粒径小、分布好;聚合温度对聚丙烯酸酯微乳液平均粒径的影响较小;随功能性单体甲基丙烯酸用量的增加,微乳液平均粒径增大明显,其加人量以不超过总质量的1.8%为宜;当甲基丙烯酸甲酯(MMA)的用量等于或大于丙烯酸丁酯(BA)的用量时,可得到纳米级微乳液.     

石油焦原料对合成碳化硅粒径及形貌的影响

原料碳化硅粉体的形貌、粒径对所制备碳化硅多孔陶瓷的孔形状和孔径大小及分布有重大影响。以不同粒径的石油焦为碳源,直接与硅粉进行反应合成了Si C粉体,X射线衍射分析表明所合成的粉体为纯的β-Si C。通过分析软件Image Pro Plus测得了SEM图中的颗粒的粒径和圆度,研究了石油焦形貌、粒径及反应温度对碳化硅形貌、粒径的影响,并分析了不同温度下石油焦粒径与碳化硅粒径之间的关系。研究结果表明:Si C在1600℃时继承了石油焦层状和片状形貌;当温度为1700℃时,碳化硅由片状转变为具有一定球形度的球状,但随着温度升高球形度变差;Si C粒径受石油焦粒径和温度的共同影响,在1800℃时石油焦的粒径可以控制碳化硅的粒径。     

影响苯丙乳液黏度与粒径的因素分析

采用种子乳液聚合法,以苯乙烯、丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯等为主要原料合成了用于制备胶粘剂的苯丙乳液。重点研究了引发剂、乳化剂及种子单体的用量及硬软单体不同配比对苯丙乳波黏度和粒径的影响。实验结果表明,当引发剂用量为0.5％（占单体总质量,后同）、乳化剂用量为1％、种子单体用量为8％、硬软单体配比为30／46的条件下,合成的笨丙乳液黏度较高、粒径小、粒度分布宽,用该乳液制备的胶粘剂具有优良的施工性能.     

核壳型苯丙微乳液的配方设计与性能研究

结合粒子设计以及"Winsor I-like"型微乳液聚合法,合成了具有核壳结构的苯乙烯-丙烯酸酯微乳液。考察了核壳单体用量、苯乙烯等用量对微乳液粒径及性能的影响。结果表明:核单体用量为30%时,聚合物微乳液的粒径最小,苯乙烯用量不宜超过30%,NMA为2%时,添加0.3%的DVB能使成膜物吸水率由10.67%下降至4.32%。     

复合高吸水性树脂的制备及其性能的研究

高吸水性树脂是一种新型多功能高分子材料,由于其具有独特的吸水保水性能,高吸水树脂在农林园艺、卫生用品、沙漠绿化及建筑等多个领域具有广泛的应用。传统的高吸水树脂主要由有机分子直接合成,这类树脂虽然吸水率高,但具有耐盐性差、吸水凝胶强度低和合成成本高等缺点,通过加入无机矿物质可大大提高树脂的性能。本文采用溶液聚合的方法,以N,N′-亚甲基双丙烯酰胺作为交联剂,过硫酸铵为引发剂,丙烯酸、丙烯酰胺为反应单体,制备出复合高吸水性树脂。研究了高岭土添加量,丙烯酰胺用量,交联剂用量,引发剂用量对树脂的吸水率的影响,同时还考察了保水性能,并对复合高吸水性树脂进行了红外表征。     

Internal curing of blended cement pastes with ultra-low water-to-cement ratio: Absorption/desorption kinetics of superabsorbent polymer

Internal curing by superabsorbent polymer (SAP) is an effective method to mitigate the autogenous shrinkage of cement-based materials with low water-to-cement ratio (w/c). In this study, the water absorption/desorption kinetics of SAP were studied quantitatively in blended cement pastes with ultra-low w/c. An absorption process at a rate of 0 to 6 g/(g h) was calculated at early ages. After that, SAPs showed mainly two distinct water desorption behaviors with a rate of 0 to 1.1 g/(g h), which was mainly governed by the osmotic pressure and capillary pressure triggered by the drop of internal relative humidity (IRH). The size and amount of SAP played a predominant role in controlling its absorption and desorption kinetics in the cement paste. Compared with ordinary Portland cement, a different desorption process with a higher release rate was noticed in binary and ternary cement pastes, primarily due to the changes in osmotic pressure resulting from the acceleration of cement hydration by silica fume at early ages. Overall, the mitigation of autogenous shrinkage is found to be highly dependent on SAP's absorption and desorption kinetics.     

黄原胶/膨润土复合高吸水性树脂的制备与性能研究

采用水溶液聚合法制备了黄原胶(XG)/膨润土有机-无机复合SAP(高吸水性树脂)。通过单因素试验法和正交试验法优选出制备复合SAP的最佳工艺条件。结果表明:丙烯酸(AA)、丙烯酰胺(AM)、XG与膨润土之间发生了接枝共聚反应;当m(AA)∶m(AM)=5∶1、AA中和度为75%、w(膨润土)=5%、w(引发剂)=1.0%和w(交联剂)=0.08%时,相应的复合SAP具有最大的吸水倍率(863.8 g/g)和吸盐水倍率(109.4 g/g)。     

Preparation of a monolithic and macroporous superabsorbent polymer via a high internal phase Pickering emulsion template

A superabsorbent polymer (SAP) possesses an ability to absorb an aqueous solution up to several hundred times its own weight. To utilize a SAP effectively, a high absorption rate is also essential in addition to a high absorption capability. Herein, using a template based on a high internal phase Pickering emulsion (HIPPE) stabilized by aluminum oxide (Al₂O₃) nanoparticles, we synthesize a SAP with a high absorption rate by forming macropores. In particular, by adjusting three different parameters, the concentration of the crosslinker, the internal volume fraction of the emulsion, and the particle concentration, we successfully formed a HIPPE-templated SAP with a high absorption rate for a saline solution, which was 51.6 g g⁻¹ of the absorbency within 10 s. We confirm that the swelling kinetics is mainly determined by the interconnectivity between the internal macro-pores. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48133.     

亚微米氧化铝粉体在建筑陶瓷板材中的应用研究

采用建筑陶瓷板的制备工艺,将亚微米氧化铝粉体加入到陶瓷板材坯料中,研究了其对陶瓷板材外观、烧结性能和力学性能的影响。结果表明:在常规的生产条件下,亚微米氧化铝粉体主要以α-Al₂O₃颗粒的形式均匀分布在坯体中,具有较强的增白效果。当氧化铝粉体加入量在15%(质量分数)以内时,陶瓷板材样品的吸水率低于0.1%,烧结致密化程度较高,抗弯强度随加入量增加而提高。当加入量继续增加,吸水率增大,抗弯强度下降。氧化铝粉体加入量为15%(质量分数)时,样品的抗弯强度达到最高值96 MPa,比未外加氧化铝的样品提高了30%。在白度较低的低品质原料中,通过加入亚微米氧化铝粉体可大幅度提高产品的白度和强度,既可减少优质资源的消耗,又能较好地满足陶瓷板材对装饰效果和力学性能的要求。     

Sulfonated polystyrene: A catalyst with acid and superabsorbent properties for the esterification of fatty acids

In this work, catalysts with acid and superabsorbent properties were obtained by sulfonation of expanded polystyrene and used to promote the esterification of oleic acid with ethanol. The prepared superabsorbent polymers (SAP) showed high concentration of active sulfonic acid sites (0.7-5.9 mmol acid sites g⁻¹) and high water absorption capacity (445-900 g_water g⁻¹). It was observed that the catalytic activity increased with the number of acid site and water absorption capacity. Turnover frequencies suggested that the catalytic activity depends on the accessibility/diffusion processes determined by the crosslinks in the polymer. Commercial sulfonic acid resins and polyacrylate based superabsorbent polymers showed very low activities compared with the SAP produced. The SAP also showed higher activity compared to the homogeneous catalyst p-toluenesulfonic acid. The higher activity of the prepared SAP is discussed in terms of the acidity of sulfonic groups combined with the water absorption which shifts the esterification equilibrium.     

Investigation of water absorption performance of polyester-woven fabrics coated with super absorbent polymer

Superabsorbent polymers (SAPs) constitute a special class of polymers widely used in various fields, especially in the hygiene and healthcare sectors. This study investigates the feasibility of achieving high water absorption capacity surfaces by coating powdered SAP using conventional coating methods onto textile surfaces. For this purpose, water-based coating pastes containing micronized SAP powder based on acrylamide/acrylic acid copolymer were coated onto polyester (PES)-woven fabric surfaces using a knife-over-roll coating technique. As the working parameters, the pH value of the coating paste, the coating thickness (the distance between the cloth and the knife), the drying/fixing temperature and time, the SAP concentration, and the water absorption capacity according to time were investigated. The results were evaluated by applying the coating thickness, the amount of coating material transferred to the fabric on the SAP-coated samples, water absorbing capacity, and centrifugal water retention tests. The obtained results have demonstrated that textile surfaces with high water absorption capacity (on average 200%–350%) can be achieved by coating hydrophobic fabric surfaces, such as PES, with SAP under suitable conditions.     

高吸水聚合物材料在防沙治沙中的应用

介绍了高吸水聚合物的发展状况、吸水机理和性能特征，总结了合成高吸水聚合物及半合成高吸水聚合物的技术条件及若干种制备方法，并提出利用低成本植物纤维素（取自植物落叶、农作物茎杆等）、淀粉等天然原材料来制备高吸水性聚合物；探讨了以高技术、低成本、大面积可实施及效果显著为技术优势，利用高吸水聚合物进行荒漠和沙漠治理的方法和发展方向。     

Visualization of water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography

Concrete cracks due to its low tensile strength. As both harmful gases and fluids may enter the concrete by migrating into cracks, the durability is endangered. The service life decreases, repair costs rise and buildings could structurally decline. In the current research, crack sealing is enhanced by the use of superabsorbent polymers (SAP). When cracking occurs, SAP particles are exposed to the humid environment and swell, sealing the crack. By means of neutron radiography, the moisture distribution is studied during capillary absorption and water permeability tests. Capillary absorption in a crack and water permeability through a crack are reduced in specimens containing SAP particles. SAP particles are able to seal the crack, thus allowing a recovery of the water-tightness of the structure. The total uptake of potentially harmful substances hereby lowers, leading to an enhanced long-term durability and lower maintenance costs.