检索结果-南通市图书馆

Studies on Rheological, Thermal, and Mechanical Properties of Polylactide/Methyl Methacrylate-Butadiene-Styrene Copolymer/Poly(propylene carbonate) Polyurethane Ternary Blends

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第12期37卷 1273-1282,I0007页

作者： Ji-li Zhao Hong-Wei Pan hui-li yang Jun-Jia Bian hui-liang Zhang Ge Gao li-Song Dong College of Chemistry Jilin UniversityChangchun 130012China Department of Science Beihua UniversityJilin 132013China Key Laboratory of Polymer Ecomaterials Chinese Academy of SciencesChangchun Institute of Applied ChemistryChangchun 130022China Zhejiang Zhongke Applied Chemistry Technology Co. Ltd.Hangzhou 310000China

Polylactide(PLA),methyl methacrylate-butadiene-styrene copolymer(MBS),and poly(propylene carbonate)polyurethane(PPCU)were blended and subjected to blown film *** rheological,mechanical,morphological,thermal,and crystalline properties of the PLA/MBS/PPCU ternary blends and the mechanical properties of the resulting films were *** of mechanical test showed that PPCU and MBS could synergistically toughen *** impact strength of 50/10/40 PLA/MBS/PPCU blend(74.7 k J/m^2)was about 7.5 times higher than that of the neat PLA(10.8 k J/m^2),and the elongation at break of 50/10/40 PLA/MBS/PPCU blend(276.5%)was higher by about 45 times that of PLA(6.2%).The tear strength of PLA/MBS/PPCU films was 20 k N/m higher than that of PLA,and the elongation at break(MD/TD)of 50/10/40 PLA/MBS/PPCU films was 271.1%/222.3%,whereas that of PLA was only 2.7%/3.0%.POM observations displayed that the density of spherulite nucleation increased and the size of crystalline particles decreased with the addition of *** increasing PPCU content from 5%to 20%,the density of spherulite nucleation increased and the size of crystalline particles decreased continuously,but the nucleation density of spherulites was slightly lowered with increasing PPCU content from 30%to 40%.The PLA/MBS/PPCU films exhibited excellent mechanical properties,which expanded the application range of these biodegradable films.

关键词： Biodegradable Polylactide Poly(propylene carbonate)polyurethane Methyl methacrylate-butadiene-styrene copolymer Films

身体姿势如何影响沉浸式虚拟现实环境下的学习?——基于学习者的空间能力视角

在线全文

学校读者我要写书评

暂无评论

现代教育技术 2024年第5期34卷 84-93页

作者：王雪成雨薇李慧洋何连青潘新叶天津师范大学教育学部天津300387 北京市朝阳区黑庄户乡人民政府北京100021 天津市第二十一中学天津300070 江门市新会华侨实验小学广东江门529100 潢川第一高级中学河南信阳464000

在沉浸式虚拟现实(Immersion Virtual Reality,IVR)应用于提升学习效果的过程中,学习者的空间能力与身体姿势是重要的影响因素。基于此,文章首先从学习者的空间能力视角,通过分组对比实验探究IVR环境下不同空间能力学习者的身体姿势对... 详细信息

在沉浸式虚拟现实(Immersion Virtual Reality,IVR)应用于提升学习效果的过程中,学习者的空间能力与身体姿势是重要的影响因素。基于此,文章首先从学习者的空间能力视角,通过分组对比实验探究IVR环境下不同空间能力学习者的身体姿势对学习的影响,结果发现:低空间能力学习者为追求良好的学习体验时可选择站位姿势,为获得更好的学习效果时可选择坐位姿势;高空间能力学习者不同的身体姿势对学习影响不大,但采用坐位姿势可以维持平和的情绪状态。之后,文章通过结构方程模型分析,揭示了不同空间能力学习者的身体姿势影响学习的路径:低空间能力学习者的站位姿势通过提升沉浸感、存在感与结果性积极情绪改善学习体验,坐位姿势则可直接提升学习效果;高空间能力学习者的坐位姿势可提升过程性中性情绪,存在感的提升也可直接提升学习效果,并通过提升沉浸感来增强结果性积极情绪。最后,文章针对IVR环境的设计与教学应用提出相关建议,以期促进IVR及教育元宇宙的良性发展,从而助推我国的教育数字化转型。

关键词： IVR环境空间能力身体姿势学习体验学习效果

维普期刊数据库博看期刊

Entropy of Dirac Field in Non-stationary and Slowly Changing Reissner-Nordstrom Black Hole

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2005年第5X期44卷 955-960页

作者： li hui-ling yang Shu-Zheng JIANG Qing-Quan Institute of Theoretical Physics China West Normal University Nanchong 637002 China

Using the thin film brick-wall model and WKB approximation, the entropy of the Dirac field in the non-stationary and slowly changing Reissner-Nordstrom (R-N) black hole is calculated. The result shows that the entropy... 详细信息

关键词： slowly changing thin brick-wall model Dirac field entropy of black hole

Cardioprotective effect of liposomal prostaglandin E1 on a porcine model of myocardial infarction reperfusion no-reflow

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第8期12卷 638-643页

作者： Jia-hui li Peng yang Ai-li li Yong WANG Yuan-nan KE Xian-lun li Department of Cardiology China-Japan Friendship Hospital Beijing 100029 China

Objective： To evaluate whether liposomal prostaglandin E1 （lipo-PGE1） can decrease reperfusion no-reflow in a catheter-based porcine model of acute myocardial infarction （AMI）. Methods： Twenty-two male Chinese mini-swines were randomized into three groups： six in a sham-operation group, and eight each in the control and lipo-PGE1 groups. The distal part of the left anterior descending coronary artery （LAD） in the latter two groups was completely occluded for 2 h, and then reperfused for 3 h. lipo-PGE1 （1 pg/kg） was injected 10 min before LAD occlusion until reperfusion for 1 h in the lipo-PGE1 group. Hemodynamic data and proinflammatory cytokines were examined before AMI, 2 h after occlusion, and 1, 2, and 3 h after reperfusion. Myocardial contrast echocardiography （MCE） and double staining were performed to evaluate the myocardial no-reflow area （NRA）. Results： Left ventricular systolic pressure and end-diastolic pressure significantly improved in the lipo-PGE1 group after reperfusion compared with the control group and also 2 h after AMI （P〈0.05 for both）. MCE and double staining both showed that lipo-PGE1 decreased reperfusion NRA after AMI （P〈0.05, P〈0.01）. lipo-PGE1 decreased serum interleukin-6 （IL-6） and tumor necrosis factor-a （TNF-a） after myocardial infarction reperfusion （P〈0.05 for both）. Conclusions： lipo-PGE1 is cardioprotective in our porcine model of myocardial infarction reperfusion no-reflow, decreasing NRA and attenuating the inflammatory response.

关键词： liposomal prostaglandin E1 (lipo-PGE1) Reperfusion no-reflow Myocardial infarction

Biodegradable Foaming Material of Poly(butylene adipate-co-terephthalate)(PBAT)/Poly(propylene carbonate)(PPC)

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2022年第2期40卷 208-219页

作者： Han-lin Tian Ze-Peng Wang Shi-ling Jia Hong-Wei Pan li-Jing Han Jun-Jia Bian Ying li hui-li yang hui-liang Zhang Changchun University of Technology School of Chemical EngineeringChangchun 130012China Key Laboratory of Polymer Ecomaterials Chinese Academy of SciencesChangchun Institute of Applied ChemistryChangchun 130022China Jilin COFCO Biochemistry Packaging Co. Ltd.Liaoyuan 136300China

A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion ***,PBAT was modified by bis(tert-butyl dioxy isopropyl)benzene(BIBP)for chain extension,and then the extended PBAT(E-PBAT)was foamed with PPC using a twin(single)screw *** analyzing the properties of the blends,we found that Young’s modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC 50/*** viscosity of the polymer has a critical influence on the formation of *** with neat PBAT(N-PBAT),the viscosity of E-PBAT increased by 3396 Pa·s and E-PBAT/PPC 50/50 increased by 8836 Pa·***,the dynamic mechanical analysis(DMA)results showed that the storage modulus(E’)at room temperature increased from 538 MPa to 1650 *** various phase morphologies(“sea-island”,“quasi-co-continuous”and“cocontinuous”)and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC ***,through the analysis of phase morphology and foaming mechanism,we concluded that the E-PBAT/PPC 70/30 component has both excellent strength and the best foaming performance.

关键词： Poly(butylene adipate-co-terephthalate) Poly(propylene carbonate) Phase structure Biodegradable foam Extrusion foaming

Experimental and theoretical analysis on the procedure for estimating geo-stresses by the Kaiser effect

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 514-518页

作者： Yuan-hui li Yu-jiang yang Jian-po liu Xing-dong Zhao College of Resources and Civil Engineering Northeastern University Shenyang 110004 China

Acoustic emission tests of the core specimens retrieved from boreholes at the depth over 1000 m in Hongtoushan Copper Mine were carried out under uniaxial compressive loading, and the numerical test was also done by using the rock failure process analysis （RFPA2D） code, based on the procedure for estimating geo-stresses by the Kaiser effect under uniaxial compression. According to the statistical damage mechanics theory, the Kaiser effect mechanism was analyzed. Based on these analyses, it is indicted that the traditional method of estimating geo-stresses by the Kaiser effect is not appropriate, and the result is usually smaller than the real one. Furthermore, the greater confining compression in the rock mass may result in a larger difference between the Kaiser effect stresses acquired from uniaxial loading in laboratory and the real in-situ stresses.

关键词： rock stresses Kaiser effect cyclic loading acoustic emission

Biodegradable Poly(butylene adipate-co-terephthalate)/Poly(glycolic acid) Films: Effect of Poly(glycolic acid) Crystal on Mechanical and Barrier Properties

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第7期41卷 1123-1132页

作者： Hong-Wei Pan Ye Wang Shi-ling Jia Yan Zhao Jun-Jia Bian hui-li yang Yan-Ping Hao li-Jing Han hui-liang Zhang Key Laboratory of Polymer Ecomaterials Chinese Academy of SciencesChangchun Institute of Applied ChemistryChangchun130022China School of Pharmaceutical Sciences Changchun University of Chinese MedicineChangchun130117China Changchun University of Technology Changchun130012China Shandong Dawn Polymer Co. Ltd.Longkou265700China

Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing conditions. PGA crystals played a major role in enhancing the mechanical and barrier properties of the films. For Film Ⅰ, there were initial PGA crystals before the film blowing process, the PGA molecular chain further crystallized, forming the oriented crystallization of PGA. Moreover, the Xcand crystalline size in Film Ⅰ were higher than those in Film Ⅱ. Compared with the different processing methods, Film Ⅰ has excellent mechanical and oxygen barrier properties due to the crystallization and orientation. The tensile strength reached 45.0 MPa, and tear strength exceeded 138.2 kN/m, while the elongation at break was as high as 750% for PBAT/PGA 85/15 in Film Ⅰ. The WVTR, WVP coefficients, and OP coefficients of PBAT/PGA films were decreased obviously with increasing the PGA content both in Film Ⅰ and Film Ⅱ. Moreover, the barrier properties of oxygen in Film Ⅰ were better than that in Film Ⅱ. This work reveals a feasible processing technique by introducing of initial crystallization of PGA to blow PBAT/PGA films with excellent mechanical and barrier properties.

关键词： Poly(butylene adipate-co-terephthalate) Poly(glycolic acid)(PGA) Biodegradable polymers Films

Rheological, Thermal and Mechanical Properties of Biodegradable Poly(propylene carbonate)/Polylactide/Poly(1,2-propylene glycol adipate) Blown Films

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2015年第12期33卷 1702-1712页

作者： Yan-ping Hao hui-li yang Gui-bao Zhang 张会良 Ge Gao li-song Dong College of Chemistry Jilin University Key Laboratory of Polymer Ecomaterials Chinese Academy of Sciences Changchun Institute of Applied Chemistry

Poly（propylene carbonate）（PPC） was blended with polylactide （PLA） and poly（1,2-propylene glycol adipate）（PPA） using a twin screw extruder. Then the PPC/PLA/PPA films were prepared using the blown film technique. DMA results showed that PPA could act as a plasticizer and improve the miscibility between PPC and PLA. Crystal morphology displayed that blending PLA with the amorphous PPC led to a decrease of the spherulite size of PLA. The results of mechanical tests indicated that PPC-rich films showed high elongation at break and PLA-rich films showed high tear strength and good optical properties. The content of PPC and PLA significantly affected the physical properties of the films. With increasing PPC content, the melt strengths of the PPC/PLA/PPA films were enhanced. These findings contributed to the biodegradable materials application for designing and manufacturing polymer packaging.

关键词： Poly(propylene carbonate) Polylactide Plasticizer Blown films.

Measurement of acceleration and angular velocity of particles during a 3D silo discharge

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第9期92卷 61-71页

作者： Tongtong Mu Yiming li Quan Chen Ran li hui yang College of Medical Instrument Shanghai University of Medicine and Health SciencesShanghai201318China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai200093China

Accurate measurement of the three-dimensional(3D)movement of discrete particles is crucial for comprehending complex granular rheology in *** this paper,the acceleration and angular velocity of particles in 3D silos are measured by using a spherical detector based on inertial technology and magnetic positioning *** acceleration of particles is the largest in the center of silos,which suggest that the resistance generated by friction and extrusion is the ***,the angular velocity distribution follows lognormal function except for particles near the *** correlation between acceleration and angular velocity is opposite in different flow *** reveals for the first time that the extent to which the resultant force on the particles affects their rotational motion is related to the flow *** results have practical significance for regulating the granular flow pattern and optimizing the structural design of silos.

关键词： Granularflow Silo Angular velocity Acceleration