Polymer Ionomers for Rapid Prototyping and Rapid Manufacturing by Means of 3D Printing

Summary: The powder blend of poly(acrylic acid) (PAA) with zinc oxide or zinc oxide/magnesium oxide was applied successfully to produce zinc polycarboxylate during the 3D dispensing of an aqueous ink by means of 3D printers (Z402? from ZCorporation and Deskmodeler? from bmt Company). The layer‐by‐layer inkjet printing afforded zinc ionomer 3D objects with excellent water resistance, no inherent color formation and high mechanical and dimensional stabilities. In contrast to the 3D printing of conventional powders such as starch/cellulose/dextrose blends, poly(vinyl alcohol) (PVA) or plaster, no postprinting treatments were required. Excellent dimensional accuracy of the models, as evidenced by very small deviation of the dimensions from those of the corresponding CAD data, was achieved. The mechanical properties improved with increasing PAA content, ink amount (saturation value), decreasing particle size of the sintered zinc oxide ceramic. At high PAA content >7 wt.‐%, post‐treatment with aqueous zinc acetate solution improved the mechanical properties. The setting time of the zinc cements shows no significant effect on the mechanical properties, but on the water resistance of the models. The porosity of the 3D objects, measured by means of X‐ray microtomography (μ‐CT), had profound impact on the variations of the mechanical properties of the 3D objects prepared by 3D printing processes.

Comparison of three‐point‐bending tests of commercially available powders with selected zinc cements (ZC1, ZC2, ZC4, ZC19). Commercially available powders printed with recommended values of manufacturer. Zinc cements printed with saturation value 1.14 (Z402?).     

Research Advancement in High-Performance Polyamides and Polyamide Blends Loaded with Layered Silicate

Polyamide comprises one of the major classes of polymers. Layered silicates (nanofiller) may enhance properties of polyamide-based hybrids even at very low content. Aliphatic polyamides (nylons) have often been chosen for commercial applications because of excellent physical and chemical properties. Aromatic polyamides (aramids) and aliphatic-aromatic polyamides have been predominantly useful as high-performance materials due to stiffness, low density, and low cost. Recently polyamide blends have become an important route to high-performance materials. Binary blends of polyamide/polypropylene, polyamide/polystyrene, polyamide/polymethyl methacrylate, polyamide/polyurethane, and others have been reported for nanocomposite formation with organoclay. However, ternary blend nanocomposite with nanoclays (PA6/mSEBS, PA6/EPDM-g-MA/H-HDPE) is rarely explored.     

GPPre: A Python-Based Tool in Grasshopper for Office Building Performance Optimization

With the development of the economic and low-carbon society, high-performance building (HPB) design plays an increasingly important role in the architectural area. The performance of buildings usually includes the building energy consumption, building interior natural daylighting, building surface solar radiation, and so on. Building performance simulation (BPS) and multiple objective optimizations (MOO) are becoming the main methods for obtaining a high performance building in the design process. Correspondingly, the BPS and MOO are based on the parametric tools, like Grasshopper and Dynamo. However, these tools are lacking the data analysis module for designers to select the high-performance building more conveniently. This paper proposes a toolkit “GPPre” developed based on the Grasshopper platform and Python language. At the end of this paper, a case study was conducted to verify the function of GPPre, which shows that the combination of the sensitivity analysis (SA) and MOO module in the GPPre could aid architects to design the buildings with better performance.     

混凝土桥及其高性能材料2020年度研究进展

为了解2020年混凝土桥及其高性能材料研究方向的发展动态,并在总结其研究内容、方法和成果的基础上更好地开展后续研究,从混凝土桥、高性能混凝土材料及高性能加劲筋材3方面着手,查阅近期文献,并进行分类、总结和评述。研究发现：目前,混凝土桥方向较为关注运维阶段的耐久性能、极端环境下的工作性能及混凝土桥运营事故等问题;高性能混凝土材料的研究进展在高性能、绿色环保以及智能化3个方面表现突出;高性能筋材则主要围绕强度更高、更耐久的FRP筋展开研究,其在梁、板、柱等构件上的应用得到积极的探索。对现有研究的不足和有待深化的问题提出初步建议,期待与相关学者共同努力,为该方向的进一步发展做出贡献。     

一种新型水煤浆聚羧酸分散剂大单体的制备

为探索一种优化的聚羧酸系分散剂大单体生产工艺,以衣康酸、聚乙二醇为原料,考察了反应物配比、反应时间、反应温度、催化剂对活性大单体酯化率的影响。实验表明,较佳反应条件为:催化剂为对甲苯磺酸,n(衣康酸)∶n(聚乙二醇)=1∶1.5,反应温度为85℃,反应时间5 h。表面性能研究结果表明,该表面活性剂有较好的表面活性,在25℃下c,mc为5.01 mmol/L,在cmc时的γ=47.1 mN/m,Krafft点<0℃。     

高效导向筛板及填料在醋酸乙烯精馏塔中的应用

对醋酸乙烯 -醋酸甲酯精馏塔进行了技术改造。采用计算机模拟精馏塔的回流比、塔板数、能耗、冷却负荷等 ,优选出最佳方案 ,即采用回流比 15、塔板数 70 ,并应用高效导向筛板塔及填料代替原浮阀塔 ,改造后生产能力、产品质量均得到提高     

聚羧酸减水剂聚醚大单体的研究进展及展望

聚羧酸系减水剂是一种新型环保的减水剂,是国内外减水剂研究的热点。介绍了聚羧酸系减水剂大单体的种类及特点,围绕聚羧酸减水剂分子结构的可设计性,可通过引入功能化的聚醚单体,开发具有减缩性、低引气性和早强的功能化产品,以满足工程需求。     

粘土对聚羧酸减水剂性能的影响及机理研究

粘土作为杂质存在于混凝土的组分如砂石中,粘土对聚羧酸减水剂有较强的吸附性,从而影响混凝土的工作性。研究了不同粘土对掺聚羧酸减水剂的水泥浆体及砂浆流动性的影响规律,探讨了聚羧酸减水剂与粘土的相互作用机理。研究结果表明,不同粘土对水泥浆体的流动性有不同程度的影响,蒙脱土和膨润土相对于高岭土及筛分土对砂浆的流动性影响更为显著;同时,相对于不掺聚羧酸的砂浆,粘土对掺聚羧酸减水剂砂浆的流动性影响更为显著。粘土自身的吸附性与疏水基的定向吸附共同作用及粘土中的金属离子与聚羧酸的螯合作用可能是粘土吸附聚羧酸减水剂的机理。     

喷射高性能水泥复合混凝土加固石拱桥节段模型试验

为了解喷射高性能水泥复合混凝土钢筋网加固石拱桥的受力机理、承载力提高幅度和破坏形态,通过3组用喷射高性能水泥复合混凝土钢筋网加固的石拱桥节段试件以及1组对比试件在分级加载下的轴压试验,探究了不同加固方式和加固层厚度对加固性能的影响。试验结果表明,加固后的石砌体开裂荷载能提高103.1%~119.8%,极限荷载提高21.2%~36.4%,喷射高性能水泥复合混凝土是一种有效的加固方法,可供工程加固设计时参考。     

Molecular-weight distributions of degradation products in selected frying oils

Polar isolates of frying oils used for frying French fries, potato chips, or French fries/tortilla chips were analyzed for nonvolatile components by high-performance size-exclusion chromatography (HPSEC) with viscometric (VIS)/refractometric (RI) detection. The degradation products were separated on three mixed-bed polystyrene/divinylbenzene columns with tetrahydrofuran as eluent. Dual VIS/RI detection of the column effluent enabled simultaneous determination of analyte molecular weights (MW) and concentrations. MW of individual components were calculated from viscosity data with the use of a universal calibration technique. HPSEC of polar samples obtained from different oilseed lines yielded triglyceride-derived products in which the corresponding nonvolatile components had variable MW and compositions. Elevated levels of high-MW components were correlated with the extent of frying oil degradation to serve as indicators for frying oil stability. MW/concentration profiles of degradation products varied notably with frying times. The distribution patterns of degradation products were markedly affected by other frying conditions and oil varieties and therefore served as fingerprint properties of specific oils. High-oleic sunflower oil (HOSUN) (used for frying French fries) appeared to be more stable than cottonseed oil: at 30 h, the concentrations of the highest MW components were 0.63 vs. 0.89 mg/100 mg oil. HOSUN (used for frying French fries/tortilla chips) tended to be more stable than sunflower oil (SUN), as the most abundant (at 30 h, 3.99 vs. 4.34 mg/100 mg oil) species were components 4 (MW=1385) and 3 (MW=2055) for HOSUN and SUN, respectively. High-oleic soybean oil (HOSBO) was notably more stable than soybean oil: at 40 h, the concentrations of the highest MW (2980 vs. 6315) components were 0.21 vs. 4.51 mg/100 mg oil. Presented in part at the 91st AOCS Annual Meeting & Expo, San Diego, California, April 2000.