全封闭型茉莉香精微胶囊的制备和表征

采用原位聚合法以有机合成密胺树脂为壁材对茉莉香精进行包覆制备香精微胶囊,并用无机纳米二氧化硅对微胶囊进行表面改性,制备出全封闭型茉莉香精微胶囊。用扫描电镜(SEM)、红外光谱仪、热重分析仪、紫外分光光度计等手段对微胶囊样品的形貌、化学组分、结构、包埋率以及封闭性进行了表征。结果表明,本文制备的全封闭型茉莉香精微胶囊具有单核壳核结构,微胶囊的囊壁具有密闭特性,香精包埋率达到18%。     

稀土离子改性有机蒙脱土及其在PET阻燃中的应用

采用离子交换法将十四烷基三丁基季膦盐和氯化稀土插入到钠基蒙脱土层间制备稀土离子改性有机蒙脱土(La-P-OMT),并采用熔融共混法制备聚对苯二甲酸乙二酯/微胶囊红磷/改性蒙脱土(PET/MRP/La-P-OMT)复合体系,对材料的热稳定性和阻燃性能进行研究。当向PET/MRP中引入La-P-OMT后,材料的热稳定性及残炭均高于不含稀土的对照体系;当PET中加入4%La-P-OMT和4%MRP之后,材料可以通过UL 94 V-0级,改性蒙脱土的加入可以促进均一、完整的炭层生成。     

哌嗪改性木质素/磷酸铝双重包覆红磷的制备与阻燃性能

以哌嗪改性木质素(LP)和磷酸铝为囊材,制备了具有多层次阻燃性能的无卤微胶囊化红磷阻燃剂,并用于改善丙烯腈-丁二烯-苯乙烯(ABS)树脂的阻燃性能。利用透射电子显微镜、扫描电子显微镜、红外光谱和热重分析等测试手段对阻燃剂的形貌和结构进行了表征,研究了阻燃剂添加量对ABS阻燃性能的影响。结果表明,红磷被LP和磷酸铝严密包覆;添加25%阻燃剂的ABS复合材料燃烧后可形成致密、厚实的残炭层,阻燃级可达到UL94 V-0等级,极限氧指数达到26.1%。与未添加阻燃剂ABS树脂相比,热释放速率峰值降低了63.1%,总烟雾释放量降低了25.8%。     

改性脲醛树脂-石蜡相变储能微胶囊的制备及表征

以三聚氰胺改性的脲醛树脂为囊壁,通过原位聚合法分别对非离子型和阴离子型石蜡乳液进行包覆,制备微胶囊。研究结果表明,采用由硬脂酸和氨水制备得到的阴离子型石蜡乳液为囊芯材料,囊芯与囊壁质量比为1.6时,包覆率达52.41%,囊壁可提供良好的热传导能力。制备得到的微胶囊热焓值为166 J/g,具有较好的相变储能效果。     

氧化石墨烯改性密胺树脂/石蜡相变微胶囊的制备及性能

通过原位聚合法制备了氧化石墨烯(GO)改性的密胺树脂(MF)/石蜡相变微胶囊。采用红外光谱、扫描电镜、差示扫描量热分析、热重分析等手段分析了相变微胶囊的微观结构及热性能,研究了GO含量对相变微胶囊形貌、包覆率和渗漏率的影响。研究结果表明,制备的相变微胶囊为较规则的球形,GO的加入并没有改变壁材或芯材的化学结构;GO改性使相变微胶囊的包覆率由91.39%提高至94.08%,增大了相变微胶囊的储能能力;GO改性相变微胶囊的防渗性能得到大幅提升,250h时的渗漏率由9.43%下降至2.68%,下降了71.6%,相变微胶囊的使用寿命得到提高。     

氧化石墨烯改性密胺树脂/石蜡相变微胶囊的制备及性能EI北大核心CSCD

通过原位聚合法制备了氧化石墨烯(GO)改性的密胺树脂(MF)/石蜡相变微胶囊。采用红外光谱、扫描电镜、差示扫描量热分析、热重分析等手段分析了相变微胶囊的微观结构及热性能,研究了GO含量对相变微胶囊形貌、包覆率和渗漏率的影响。研究结果表明,制备的相变微胶囊为较规则的球形,GO的加入并没有改变壁材或芯材的化学结构;GO改性使相变微胶囊的包覆率由91.39%提高至94.08%,增大了相变微胶囊的储能能力;GO改性相变微胶囊的防渗性能得到大幅提升,250h时的渗漏率由9.43%下降至2.68%,下降了71.6%,相变微胶囊的使用寿命得到提高。     

纺丝原液原位合成相变材料微胶囊制备石蜡/PVA储能纤维

以聚乙烯醇(PVA)纺丝原液为分散介质, 常温相变材料RT27石蜡为芯材, 正硅酸乙酯(TEOS)为聚合单体形成SiO₂囊壳, 通过原位聚合直接制备含有石蜡微胶囊的PVA纺丝原液, 之后通过湿法纺丝制备石蜡/PVA储能纤维。通过正交实验优化, 结合粒径分布软件, 分析各因素对微胶囊粒径的影响, 选择适合纺丝的微胶囊合成条件。采用FTIR-ATR、SEM、EDS及TEM表征了纤维及微胶囊的化学成分及形态, 通过DSC、TGA表征了微胶囊的包覆率、纤维的储能性及热稳定性。结果表明: PVA纺丝原液中合成了SiO₂凝胶包裹的相变微胶囊, 其平均粒径为1.39 μm, 大小及分布适合纺丝。纤维相变焓值为45.39 J/g, 石蜡包裹率高达94.72%, 纺出纤维具有较高的储能性和较好的热稳定性。     

纳米石墨改性石蜡相变微胶囊的制备及性能表征

以石蜡为芯材,聚砜为壳材,纳米石墨为改性剂,采用溶剂挥发法制备了纳米石墨改性石蜡相变微胶囊.通过SEM、FT-IR、DSC、TGA等对相变微胶囊进行表征,研究添加不同剂量纳米石墨对相变微胶囊的表面形貌、化学结构、相变特性、热稳定性以及包裹率的影响.结果表明,当纳米石墨添加量为1.5％时,微胶囊的整体性能最好,平均粒径为...     

苯并噁嗪与微胶囊红磷及丁腈橡胶对ABS的阻燃增韧

采用苯并噁嗪(BOZ)与微胶囊化红磷(MRP)复配制备了无卤阻燃丙烯腈-丁二烯-苯乙烯共聚物(ABS)。研究了BOZ/MRP质量比和用量对阻燃ABS性能的影响。然后固定BOZ和MRP的用量,考察丁腈橡胶(NBR)的添加量对BOZ/MRP/ABS阻燃体系阻燃性能和力学性能的影响。结果表明,BOZ/MRP质量比为3:2,总量为20%(质量分数)时,可制得氧指数(LOI)达24.4%,垂直燃烧达UL-94 V-0级的无卤阻燃ABS;BOZ受热产生的酚羟基与红磷燃烧产生的氧化磷等发生酯化反应减缓了ABS的分解;NBR添加量为8%时,阻燃体系垂直燃烧达V-0级,拉伸强度为30.8 MPa,缺口冲击强度达11.4 kJ/m2。     

不同粒度及包覆改性高氯酸铵的热分解性能和安全性能研究

采用扫描电子显微镜和X射线衍射仪对不同粒度及包覆改性高氯酸铵(AP)颗粒的分散性及晶相进行了表征,并通过差示扫描量热法和机械感度测试研究不同AP样品的热分解性能和安全性能。结果表明,随着AP粒度增加,颗粒分散性得到一定改善,相同粒度的包覆改性AP分散性优于普通AP;不同粒度及包覆改性AP的晶相均一致;AP粒度越小,其热分解性能越好,对于粒度相同的AP,包覆改性对其热分解性能影响不大;随着AP粒度增加,其撞击感度和摩擦感度均降低,平均粒径(d_(50))分别为1μm、3μm和6μm的AP其撞击感度和摩擦感度分别为96%、80%、64%和28%、28%、16%;包覆改性可以明显降低AP的感度,d_(50)为3μm的包覆改性AP与粒度相同的普通AP相比,撞击感度和摩擦感度分别降低了28%和16%。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.