共查询到20条相似文献，搜索用时 62 毫秒
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对比了模压法及直接切片法制样,以及用铬酸-硫酸溶液、盐酸、乙酸乙醇等不同方法蚀刻所得的扫描电子显微镜图象,结果表明直接切片法比模压法制的试样更能反映CaCO_3/聚丙烯界面形态及CaCO_3的分布情况;试样经盐酸或乙酸乙酯蚀刻后的界面形态显露更为清楚,后者并能显露出聚丙烯酸酯在界面及基体中的分布状态;铬酸-硫酸蚀刻面主要揭示晶相与非晶相连CaCO_3粒子的分布及晶相的形态。受潮CaCO_3导致加工过程出现空穴,减压亦不能消除,受氧化的聚丙烯和聚丙烯酯均有利于CaCO_3粒子与聚丙烯的粘结。 相似文献
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先将β成核剂TMB-5制成母粒,再用于改性聚丙烯（PP）．研究结果表明TMB-5的加入对聚丙烯的拉伸强度影响小,但聚丙烯的简支梁缺口冲击强度和断裂伸长率均有较大幅度提高,TMB-5用量为0．1％时,聚丙烯的简支梁缺口冲击强度达到17．6kJ／m^2．TMB-5的加入可以提高聚丙烯的耐磨性能,TMB-5用量为0．3％时,聚丙烯的耐磨性能最佳．差示扫描量热（DSC）、广角X衍射（XRD）的研究表明：TMB-5对聚丙烯的结晶不仅具有明显的成核作用,而且部分改变了聚丙烯的晶型． 相似文献
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用流延法制备壳聚糖膜,并对其进行湿热处理。傅立叶变换红外(FT-IR)光谱图和X-射线衍射(XRD)谱图分析表明,经湿热处理后壳聚糖膜内有类似胺结构形成,并在XRD谱图中的水合结晶峰减弱和无水结晶峰增强。 相似文献
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探讨了几个反应条件制得的聚丙烯的熔体结晶形成的结构问题,表明改变聚合温度等条件,不仅产物的等规度、结晶动力学过程受影响,而且β晶的形成能力有明显差异;在现有实验条件下,乙烯共聚改性产物不形成β晶,且随结晶条件改变,2θ=21°衍射峰高不同,它反映形成聚乙烯的结晶多少不同,若共聚物中有足够的长度的聚乙烯链段的话。 相似文献
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分峰计算结晶度的问题探讨 总被引：1，自引：0，他引：1
应用分峰方法计算结晶度,首要条件是结晶聚合物的形态结构必须符合"两相模型"。通过聚合物材料的分析,发现Jade软件的分峰程序固然很好,但其受到扫描范围、基线、非晶峰位置及分布的影响很大,计算的结晶度值有一定的随意性,只能作相对比较,且结晶度值偏大。用X射线衍射法测定的结晶度与其他实验方法获得的结晶度无可比性,还常遇到背景散射的基线不平和非晶峰难以确定等现象。对此进行探讨和交流。 相似文献
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采用DSC研究了稀土化合物氧化镧、硬脂酸镧对LLDPE(线性低密度聚乙烯)非等温结晶行为的影响。随着氧化镧和硬脂酸镧浓度的增加,LLDPE的结晶度出现下降的趋势。氧化镧可起到异相成核的作用,使LLDPE的结晶速率增快,冷却结晶峰向高温移动,而硬脂酸镧没有改变结晶峰的位置,对结晶速率没有影响。广角XRD(X射线衍射)结果显示氧化镧和硬脂酸镧没有使LLDPE的晶型产生变化,但在有氧化镧的体系中,LLDPE在110和200晶面的晶粒尺寸有明显增大。力学实验显示,氧化镧使LLDPE的拉伸强度略有降低,断裂伸长率则有较大幅度的下降。硬脂酸镧对LLDPE的拉伸强度影响不大。却使断裂伸长率有大幅度提高。 相似文献
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庞键 《铜陵职业技术学院学报》2007,6(4):64-66
加入成核剂是结晶型聚合物公认最方便而有效的聚烯烃改性方法。聚丙烯成核剂可使聚丙烯的结晶细微化、结晶度增加,冲击强度、透明度、热变形温度等性能得到提高,成型性得到改善。本文综述了聚丙烯成核剂的种类、特性、国内外现状和最新进展。 相似文献
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用差示扫描量热仪（DSC）研究了聚丙烯（PP）和具有不同接枝率的聚丙烯接枝甲基丙烯酸甲酯（PP—g—MMA）的非等温结晶行为,用Avrami方程、莫志深（M0）方程、Dobreva方法和Kissinger方法对该过程进行分析,得到相应的非等温结晶动力学参数．通过对这些参数分析可得出,PP接枝MMA对PP结晶的成核和生长机理存在两方面影响：（1）起成核剂作用,促进PP的成核;（2）会破坏PP结晶的规整性,使PP难规则排列,影响其结晶过程和规整度．因此,对PP结晶来说有一最佳的接枝率,此时,接枝的MMA表现为促进PP的结晶． 相似文献
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基于Haake转矩流变仪,分别将α和β成核剂熔混到等规聚丙烯中以改变其结晶形态.用偏光显微镜法、X射线衍射法和力学性能测试方法研究了疲劳作用前后α晶和β晶相互转变及其结构性能.实验结果表明:α成核剂在降低球晶尺寸和增加结晶度同时,在晶胞内产生了内应力,在疲劳初期,结晶应力消除、拉伸强度增加,继续疲劳时,结晶度和拉伸强度都下降,疲劳后,β含量相对增加.当β成核剂用量较少时,β晶含量增加,拉伸强度降低;在β晶结晶度适中时,疲劳并不改变晶胞结构与结晶度,表现较好的耐疲劳性;结晶度较高时,疲劳降低了结晶度,但拉伸强度有所增加. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献