新型改性聚乳酸及其亲/疏水性研究

合成了基于马来酸酐改性聚乳酸（MPLA）和丁二胺的新型改性聚乳酸（BM-PLA），旨在提高聚乳酸的亲水性，克服乳酸和MPLA在降解过程中的酸性，并为进一步引入多肽和胶原等生物信号分子提供活性基团。通过红外光谱测定到了丁二胺已成功引入到MPLA中，利用接触角和吸水率评价了BMPLA的亲/疏水性变化，表明丁二胺改性所得BMPLA的亲水性相对于PDLLA和MPLA已大大改善，测定了材料在12周降解过程中的pH变化。表明丁二胺改性聚乳酸不表现酸致自加速降解特征，未出现pH陡降现象，已完全克服了聚乳酸和马来酸酐改性聚乳酸降解过程中的酸性，上述研究结果提示，丁二胺改性聚乳酸是一族新型的具有优良亲水性和良好降解行为的组织工程材料，预示着它可望具有优良的细胞亲和性，在组织工程中具有重要的应用潜力。     

反应挤出法制备马来酸酐接枝聚乳酸

采用反应挤出方法制备了聚乳酸(PLA)与马来酸酐(MAH)的接枝共聚物,研究了工艺条件和配方对产物接枝率和熔体流动速率的影响。结果表明,聚乳酸的接枝反应主要依赖于大分子侧链自由基进行,过高的螺杆转速或过高的挤出反应温度会引发聚乳酸的降解反应,不利于产物接枝率的提高;在适宜的反应条件下(马来酸酐含量2%,DCP含量0.35%,温度180℃,螺杆转速100 r/min),可以方便制得马来酸酐接枝聚乳酸产物(接枝率≥0.45%);SEM观察显示,马来酸酐接枝聚乳酸有效改善了PLA/淀粉共混材料的相容性。     

超临界CO2反复循环萃取法制备PLA/TCP多孔组织工程支架材料

相对于传统的超临界CO2（SC—CO2）一次性升压法，采用SC—CO2反复循环萃取法制备了聚乳酸（PLA）／磷酸三钙（TCP）复合多孔支架材料，以提高材料的孔洞连通率。本文研究了材料的开孔率，不同PLA和TCP配比材料的孔洞形态以及材料的力学性能。结果表明，反复循环萃取法制备的材料比传统的一次性升压法制备的材料的开孔率可以提高10%左右，孔径在200-300μm之间，孔壁上有丝网型等几种适合细胞种植的特殊微隙形态；TCP在PLA支架中的分散性很好；材料压缩模量和压缩强度分别可达71.8和7．1MPa，比单纯的PLA材料明显增加。     

MAH/GMA共接枝聚乳酸对木粉/PLA复合材料性能的影响

采用熔融接枝法分别制备马来酸酐接枝聚乳酸、甲基丙烯酸缩水甘油酯接枝聚乳酸和马来酸酐/甲基丙烯酸缩水甘油酯共接枝聚乳酸,并利用红外光谱对接枝共聚物进行结构表征。分别以三种接枝共聚物为相容剂,采用注塑成型制备了木粉/PLA复合材料。利用扫描电子显微镜(SEM)对复合材料的断面形貌进行微观分析,结果表明,加入不同接枝共聚物后木粉/PLA复合材料两相看不出明显相界面,界面相容性得到改善。对不同接枝共聚物制备的复合材料的力学性能、加工流动性能和动态流变性能测定的结果显示,加入MAH/GMA共接枝聚乳酸后的木粉/PLA复合材料和未添加相容剂的复合材料相比,拉伸强度和冲击强度分别提高了9.54%和7.23%,复合体系的平衡扭矩和剪切热提高,储能模量及复数黏度均增大。     

聚(D,L-乳酸)基仿生聚合物材料的合成与表征

探索一种新型聚乳酸基仿生聚合物材料的制备新方法.具体实验步骤是:利用聚乳酸上叔碳原子的自由基反应活性,在过氧化二苯甲酰的催化作用下,将马来酸酐引入聚乳酸侧链上,以此提供高反应活性的酸酐键;然后利用酸酐基团与-NH2发生N-酰化反应这一特点,将脂肪族二胺引入聚乳酸侧链上,从而克服聚乳酸降解产物的体液环境呈酸性的缺陷;再用碳二亚胺作缩合剂,在二胺改性聚乳酸材料中共价引入一种细胞粘附肽段Arg-Gly-Asp-Ser(RGDS),赋予材料生物活性和生物特异性,这样就制备了一种新型聚乳酸基仿生材料.采用MALLS、FTIR和XPS对仿生材料进行结构表征;采用罗丹明比色法、茚三酮显色法和氨基酸分析仪检测法对仿生材料中的马来酸酐、二胺和粘附肽RGDS进行定量测定.结果表明,按文中所述之制备技术,在不改变聚乳酸材料主链结构的前提下,该仿生材料中粘附肽RGDS的含量是5.12μmol/g.这就形成了一种具有类似细胞外基质的新型仿生材料.     

高分子专利

专利名称:一种生物活性聚乳酸的制备方法、产品及应用专利申请号:200310121036.7公开号:CN1556130申请日:2003.12.31公开日:2004.12.22申请人:潘君本发明提供了一种采用马来酸酐改性的聚乳酸和生物活性物质为原料,制备生物活性聚乳酸材料的方法及其产物和应用,方法步骤:1直接加     

E-MAH-GMA共混增韧改性PLA的研究

聚乳酸(PLA)中加入不同比例的乙烯-马来酸酐-甲基丙烯酸缩水甘油酯三元嵌段共聚物(E-MAH-GMA)对其进行增韧改性。用傅立叶变换红外光谱仪对材料进行表征;用熔融指数测量仪对流动性进行分析;同时测试了材料拉伸、冲击、弯曲等力学性能,结果表明:E-MAH-GMA对PLA有增韧作用,添加20份的E-MAH-GMA时,PLA共混材料的冲击强度为95.71kJ/m2,比纯的PLA提高了408%;拉伸强度、弯曲强度有所下降,断裂伸长率略有提高。     

马来酸酐化在聚合物材料设计中的应用

马来酸酐化在聚合物材料设计中有广泛的应用，可酸酐化的聚合物有聚烯烃、双烯烃聚合物和极性聚合物。由酸酐化聚合物可以进行以下几方面的设计：（１）极性基团的引入；（２）梳型支化结构的产生；（３）交联网络的形成；（４）荧光标记聚合物的制备；（５）界面增容作用的形成；（６）偶联作用。     

界面改性对GMT—PP复合材料力学性能的影响

研究了不同界面状态对ＧＭＴ－ＰＰ复合材料层间剪切强度,弯曲强度及模量,压缩强度及模量,冲击强度等力性能的影响。实验结果表明,基体中填加光引发和ＢＰＯ引发的马来酸酐接枝聚丙烯且玻纤表面用硅烷偶联剂处理可显著提高复合材料界面强度,进而提高其宏观力学性能。     

马来酰己二胺酸改性聚乳酸的合成与表征

以马来酸酐和己二胺为原料制备出了一种新型的马来酰己二胺酸单体（HOOC-MAH-HDA-NH2）,然后采用自由基熔融接枝技术将HOOC-MAH-HDA-NH2引入到PDLLA骨架中,形成了结构与己二胺改性聚乳酸（HMPDLLA）相似的MHP-DLLA材料。采用红外光谱（FT-IR）、核磁共振氢谱（1 H NMR）、核磁共振碳谱（13 C NMR）和DEPT 135对HOOC-MAH-HDA-NH2和MHPDLLA的化学结构进行了定性和定量表征。以PDLLA为空白,HMP-DLLA为对照,对MHPDLLA的分子量进行了测定。结果表明采用新的合成工艺使聚合物的分子量从原有的66%～68%降低到了33%～34%,且合成路线更简单。在合成路线和合成工艺上的创新为MHPDLLA用作生物活性材料或仿生材料的基质材料开辟了更广阔的空间。     

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.