改性瓜尔胶/聚氨酯复合微球的制备及性能研究

采用环氧丙烷改性瓜尔胶制备得到羟丙基瓜尔胶,再将其与聚氨酯复合制备微球,并对复合微球的性能进行了研究。结果表明:羟丙基瓜尔胶含量在0.1%~0.3%时,复合微球球形较好;溶胀度随着羟丙基瓜尔胶含量的增加而增加;扫描电镜结果显示,复合微球表面有孔隙,内部呈半中空状态;复合微球的降解速率在碱性环境下较快,酸性环境下较慢;羟丙基瓜尔胶含量越高,药物释放速率越快。     

阳离子羧甲基羟丙基瓜尔胶的制备及其助留助滤性能研究

以1-烯丙基-3-甲基咪唑乙酸鎓盐([AMIM]Ac)为反应介质,3-氯-2-羟丙基三甲基氯化铵(CTA)、氯乙酸钠、环氧丙烷为改性剂,创新性的一步制备了阳离子羧甲基羟丙基瓜尔胶(CCMHPG)。研究了3种改性剂用量、碱用量、反应温度、反应时间对产物取代度和粘度的影响,确定了最佳制备条件。经测定,反应产物的阳离子取代度为0.24,羧甲基取代度为0.41,羟丙基取代度为0.36,产物水溶性较好,1%水溶液粘度达1 072 mPa·s。CCMHPG的红外谱图和~1H NMR谱表明季铵基团、羧甲基和羟丙基均已成功接枝到瓜尔胶分子上,电镜照片显示颗粒表面出现了褶皱及鳞片状裂纹。将CCMHPG/PAC二元微粒体系用于脱墨废纸浆,PAC添加量为0.8%、CCMHPG添加量为0.04%时的留着率为94.3%,打浆度为43°SR。     

瓜尔胶与甲基丙烯酸缩水甘油酯的接枝共聚合

以硝酸铈铵(CAN)为引发剂,采用溶液聚合法,制备了瓜尔胶与甲基丙烯酸缩水甘油酯的接枝共聚物(GGgGMA).研究了反应条件对接枝率的影响,在反应温度为50℃,瓜尔胶浓度为5g/L,硝酸铈铵占瓜尔胶单体质量分数为12%,甲基丙烯酸缩水甘油酯用量为4 mL,反应时间为6h时,接枝率达最大值,并对接枝共聚物用红外光谱FT-...     

甘蔗渣超微粉/瓜尔胶共混体系的相容性研究

利用流变仪考察了甘蔗渣超微粉(BP)/瓜尔胶共混体系的相容性。对共混物进行稳态剪切扫描和动态频率扫描测试后,根据Utraki原理、复合黏度、储存模量及损耗模量分析、Cole-Cole曲线,以及时温叠加原理等理论对数据进行处理分析,发现BP/瓜尔胶=50/100(质量比)时,两者相容性较好。同时,扫描电镜结果表明,随着BP含量的增多,BP与瓜尔胶两者相容性逐渐变差,与流变分析结果一致。     

醇对瓜尔胶高分子水溶液黏度的影响

潮定了异丙醇和乙二醇对瓜尔胶高分子水溶液黏度的影响,发现随着异丙醇的加入,瓜尔胶高分子水溶液的特性黏数逐渐减小,Huggins相互作用参数会逐渐增加;与此相反,随着乙二醇的加入,瓜尔胶高分子水溶液的特性黏数逐渐增加,Huggins相互作用参数却逐渐减小.醇和瓜尔胶高分子之间缔合导致高分子链疏水性质和空间位阻效应的改变,...     

丙烯酰胺-阳离子瓜尔胶的低温接枝聚合

用硫酸铈铵引发阳离子瓜尔胶与丙烯酰胺的低温(10℃)水溶液接枝聚合,重点研究单体与引发剂浓度对接枝参数的影响规律,获得了最佳聚合条件。实验表明,阳离子瓜尔胶与丙烯酰胺的聚合速度明显快于未改性瓜尔胶;随着单体浓度的增加,转化率、接枝率逐渐增加,接枝效率高达95%;进一步增加单体浓度(>1.3 mol/L),转化率、接枝率下降速度较快,接枝效率下降缓慢;随着引发剂浓度增加,转化率和接枝率增加到最大值,而引发剂浓度继续增加(>3.3×10-4mol/L),所有接枝参数下降。红外光谱图和热失重数据证实发生了接枝聚合反应。     

苯乙烯/黏土协同作用对瓜尔胶复合高吸水凝胶性能影响

在瓜尔胶-g-聚丙烯酸钠/无机黏土(GG-g-PNaA/Clay)体系中引入疏水单体苯乙烯(St)参与接枝共聚,水溶液聚合法合成了瓜尔胶-g-聚(丙烯酸钠-co-苯乙烯)/无机黏土(GG-g-P(NaA-co-St)/Clay)复合凝胶。用红外光谱、紫外光谱和扫描电镜对复合凝胶进行了表征,考察了St与无机黏土的协同作用对凝胶三维网络和溶胀性能的影响。实验结果表明,当黏土的质量分数为10%时,随着St的加入,凝胶平衡溶胀倍率(Qeq)呈现先增大后降低趋势;当St质量分数为1.5%时,凝胶Qeq达到最大值。St与凹凸棒黏土、海泡石和蛭石协同作用,不仅使复合凝胶表面形貌粗糙度增加,孔洞增多,而且也使Qeq分别提高了48.9%、50.3%和37.5%。此复合凝胶在0.9%NaCl溶液和一定pH溶液中的Qeq也明显提高,并且经过5次溶胀-去溶胀平衡后,均表现出良好的盐和pH响应性。     

浙江丰利瓜尔胶粉碎机市场受宠

<正>日前,国家高新技术企业浙江丰利粉碎设备有限公司迎来了一批又一批客商,他们专门前来订购瓜尔胶专用超微粉碎机。最近一种名叫瓜尔胶的粉体受到了市场热捧,从而带动了加工设备的热销。瓜尔胶是由瓜尔豆籽经磨碎、筛分、吹风除皮和胚芽、胚乳处理等工序加工制成的自由流动粉末。瓜尔胶主要分为食品级和工业级两种,是已知的最有效和水溶性最好的天然聚合物。其独特的分子结构特点及天然性使其迅速成为性能优越的新型环保造纸助剂。同时它还被广泛应用于食品、制药、化妆品、个人保健、石油、粘蚊剂、造纸和纺织印染等行业,用     

瓜尔胶-g-聚丙烯酸/OMMT纳米复合吸水性树脂的制备与表征

以瓜尔胶(GG)、季按盐改性的蒙脱土(OM-MT)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,在水溶液中通过接枝聚合反应制备了瓜尔胶-g-聚丙烯酸/OMMT纳米复合吸水性树脂.研究了OMMT的含量、MBA的浓度对产物吸水倍率的影响,考察了OMMT的引入对产物反复溶胀性能的影响.并用傅利叶变换红...     

交联度对瓜尔胶-g-聚丙烯酸/腐植酸钠高吸水性树脂性能的影响

以天然瓜尔胶(GG),丙烯酸(AA)和腐植酸钠(SH)为原料,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,过硫酸铵(APS)为引发剂,采用水溶液聚合法制备了不同交联度的瓜尔胶接枝聚丙烯酸/腐植酸钠(GG-g-PAA/SH)高吸水性树脂。研究了交联度对树脂的表面形态、溶胀动力学、盐敏感度和反复溶胀性能的影响。扫描电镜(SEM)和溶胀性能测试结果表明,交联度的增加可以改善高吸水性树脂的均匀度,提高吸水速率,降低对盐的敏感度,以及改进树脂的反复溶胀性能。     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to