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1.
以碳纤维为增强体,在较宽的温度范围内(50~350℃),对不同固化条件下的双酚A型聚苯并 口恶 嗪进行动态力学分析(DMA),研究其高温松弛行为。tanδ温度谱上多个峰的出现,表明双酚A型聚苯并口恶嗪有多重高温松弛行为。原子力显微镜用来研究聚苯并口恶嗪浇注体弯曲断面的微观形貌,结果表明:双酚A型聚苯并口恶嗪的交联网络为非均相结构,高模量的“致密相”分散在低模量的“疏松相”中。聚苯并口恶嗪的多重松弛行为与其微观非均相结构相关。低官能度苯并口恶嗪的加入有利于化学交联的高模量致密相的形成,使聚合物的α3松弛峰高降低。  相似文献   

2.
以二胺型苯并噁嗪为前驱体,通过浸涂和热固化的方法在低碳钢表面制备了聚苯并噁嗪涂层。二胺型聚苯并噁嗪涂层具有良好的成膜性,并对低碳钢基体具有良好的附着力。采用动电位极化测试和交流阻抗测试考察了固化温度对聚苯并噁嗪涂层防腐蚀性能的影响。结果表明:不同固化温度制备出的聚苯并噁嗪均具有良好的防腐蚀效果;其中,固化温度为150℃时所制备的涂层防腐蚀性能最佳,腐蚀电流为1.49×10~(-8) A/cm~2,相比空白低碳钢样品的腐蚀电流(6.91×10~(-6)A/cm~2)下降了2个数量级。  相似文献   

3.
以对甲酚-苯胺型苯并噁嗪为模型化合物,玉米秸秆木质素为固化催化剂,用1H-NMR研究木质素催化苯并噁嗪的聚合机理。随后将木质素与双酚A-苯胺型苯并噁嗪共混,得到不同木质素质量分数(0、0.5%、1%、2%、5%)的共混体系。通过DSC研究了共混体系的固化行为,并用DMA、TGA对固化产物热性能进行测试。结果表明:在木质素催化作用下,苯并噁嗪首先开环聚合生成含苯氧结构和Mannich桥结构的中间体,而苯氧结构中间体不稳定,会重排生成Mannich桥结构的最终产物;木质素的引入显著降低了苯并噁嗪的固化温度,且随着木质素含量的增加,共混体系的起始固化温度和固化峰值温度均逐渐降低;与聚苯并噁嗪相比,共混体系固化产物的玻璃化转变温度升高,分解温度略有下降,800 ℃时的残炭率有所提高。  相似文献   

4.
芴基苯并噁嗪单体的合成及热性能研究   总被引:1,自引:0,他引:1  
以双酚芴、环己胺和甲醛为原料,采用混合溶剂法合成了一种新型双官能度芴基苯并噁嗪单体,利用FTIR,1H NMR和13C NMR对产物结构进行了表征,以差式扫描量热仪(DSC)研究了芴基苯并噁嗪单体的固化行为,通过DSC和热重(TGA)分析了聚苯并噁嗪的热性能.结果表明,芴基聚苯并噁嗪树脂呈现出典型的热开环固化特征,放热峰顶温度为251℃,玻璃化转变温度Tg为189.4℃,初始热分解温度(热失重5%)达329℃,800℃时的残碳率达到31%.  相似文献   

5.
以4-氰基苯酚、苯胺、多聚甲醛为起始原料,以甲苯为溶剂制备了苯并噁嗪中间体。用FTIR、1 HNMR和13 CNMR对苯并噁嗪中间体进行了表征,同时,用DSC对其固化行为进行表征。通过TGA对聚苯并噁嗪的热稳定性进行了测试。DSC研究结果表明:苯并噁嗪中间体的熔融温度为117.90℃,开环聚合的起始温度为225.00℃,固化峰值温度为232.10℃,低于类似结构的苯酚/苯胺型苯并噁嗪。TGA研究表明:聚苯并噁嗪5%热失重温度为302.26℃,10%热失重温度为351.85℃,最大失重速率温度为433.91℃,残炭率为55.63%。与其他类似结构的苯并噁嗪相比,氰基的引入使其固化物的残炭率和热稳定性明显提高。  相似文献   

6.
以生物质原料双酚酸甲酯(MDP)和双酚A(BA)为酚源,以聚醚胺D230为胺源与多聚甲醛经Mannich反应制得不同比例BA与MDP的苯并噁嗪前驱体.利用核磁共振(~1H NMR)和红外光谱(FTIR)对苯并噁嗪前驱体的化学结构进行了表征,结果表明制备得到的产物与所设计的结构相符.利用差示扫描量热法(Differential Scanning Calorimeter,DSC)对得到产物的热性能进行表征,结果表明所得前驱体的固化起始温度(T_(onset))为208.0~225.9℃,固化峰值温度(T_(peak))为240.0~246.6℃,与石油基纯BA制备得到的前驱体样品比较,两者固化温度相当.通过热重分析(Thermogravimetric Analysis,TGA)和拉伸试验对聚苯并噁嗪的力学性能进行了测试,结果表明,制得的聚苯并噁嗪具有较好的热稳定性和力学性能,得到的产物中MDP所占比例最高的聚苯并噁嗪PBA/MDP010-D230具有最佳综合性能.热重分析结果表明,PBA/MDP010-D230在氮气氛围下的5%热失重温度和10%热失重温度分别为356.3℃和373.0℃,且其在氮气氛围中800℃下的残炭率可达38.3%.PBA/MDP010-D230的力学性能测试显示其拉伸强度高达68.9 MPa,同时具有6.6%的断裂伸长率,这一结果表明了其具有较好的力学性能.  相似文献   

7.
以双酚AF为原料,通过硝化和还原合成得到含氟苯并噁唑聚合物的单体2,2-双(4-羟基-3-氨基苯基)六氟丙烷(3)。将等摩尔量的对苯二甲酰氯与化合物3反应制得邻羟基酰胺聚合物5,然后再高温脱水环化即得到含氟聚苯并噁唑聚合物6。通过红外、质谱和核磁等表征手段确定了双酚AF的硝化产物2和含氟苯并噁唑聚合物单体3结构。邻羟基酰胺聚合物5及含氟聚苯并噁唑聚合物6的结构由红外表征确定。热重分析表明,含氟聚苯并噁唑聚合物6的5%失重温度为530℃,分解温度为573℃,具有良好的热稳定性。  相似文献   

8.
聚苯并噁嗪预聚体的结构与固化行为的研究   总被引:4,自引:1,他引:3  
采用以甲苯为溶剂的溶液法合成了一种成环率高的聚苯并噁嗪预聚体即聚双 (3,4-二氢-3-苯基-1-,3-苯并噁嗪)预聚体, 通过1H-NMR、FT-IR、GPC和DSC对预聚体的结构和固化行为进行了研究。结果表明 ,该预聚体的成环率与溶剂的极性有关, 溶剂极性越强, 成环率越低; 成环率对预聚体的固化温度和Tg有一定的影响, 成环率越低, 预聚体的固化温度越低, 其固化产物的Tg越低。  相似文献   

9.
通过辊涂和热固化技术在低碳钢表面制备硅烷改性主链型聚苯并噁嗪涂层,该涂层具有良好的成膜性和疏水性。采用电化学阻抗谱法研究了硅烷改性对主链型聚苯并噁嗪涂层防腐蚀性能的影响。结果表明:硅烷的引入能够提高主链型聚苯并噁嗪涂层的防腐蚀性能;当巯丙基三甲氧基硅烷与苯并噁嗪前驱体的质量比为40∶100时,所制备的涂层防腐蚀性能最优,涂层在0.01 Hz处的阻抗值达到6.29×10~8Ω·cm~2,相比空白低碳钢片提高了5个数量级。  相似文献   

10.
选取六种不同酚源的烯丙胺型苯并噁嗪,研究苯并噁嗪官能团结构上不同取代基团对此类苯并噁嗪中间体的性质及其树脂热性能的影响。FT-IR测试结果显示,取代基团影响噁嗪环的特征吸收峰值,噁嗪环特征峰随场/诱导效应常数的增大而降低。同时,场/诱导效应的增大降低了苯并嗪中间体中官能团的反应温度。通过DMTA和TG分析了六种聚苯并噁嗪树脂,结果显示,场/诱导效应的增大虽能增大噁嗪树脂的残碳率,但降低了噁嗪树脂的耐热性能和热稳定性。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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