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1.
采用凝胶渗透色谱(GPC)测定一种热塑性聚酰亚胺(TPI)的分子量及其分布;利用差示扫描量热仪(DSC)测定TPI的玻璃化转变温度(Tg);考察了分子量大小、热处理温度和热处理时间对玻璃化转变温度的影响.结果表明:Tg随数均分子量的增大而增加,采用Kanig-Ueberreiter方程关联Tg与数均分子量,其线性拟合度最高;由于聚酰亚胺的结构特点--存在自由端基,在高温可发生固相热环化反应,相应其分子量随处理温度的升高和处理时间的延长而增大,表现为聚合物的Tg有所升高.  相似文献   

2.
以2,3,3’,4’-联苯四甲酸二酐(a-BPDA)为二酐,以3,4’-二氨基二苯醚(3,4’-ODA)和间苯二胺(m-PDA)为混合二胺,并以邻苯二甲酸酐(PA)封端,采用高温一步法制备了4种不同分子量的具有扭曲分子主链结构的热塑性聚酰亚胺(TPIs)。并对此系列热塑性聚酰亚胺的热性能、熔体黏度及机械性能进行了一系列的考察。研究发现,TPI-B树脂具有良好的综合性能:Tg为305℃,在380℃熔体黏度为6970Pa.s,拉伸强度为62MPa,弯曲模量为135MPa,兼具高Tg及良好的加工性能。  相似文献   

3.
六十年代中期,由于航空航天技术的发展,迫切需求能用于大型机架结构的高性能复合材料。原有的C-型聚酰亚胺虽然可以承受316℃高温,但因在成型加工过程中有缩合水和残留溶剂放出的现象,即使在高压下进行成型加工,也不能制得无气隙的结构复合材料。因此,人们把主攻方向放到A-型聚酰亚胺的研究开发方面。A-型聚酰亚胺是由不同封端剂封端的低分子量齐聚物。这种聚酰亚胺的特点是:对增强材料浸润性好;在成型加工中通过加成反应机理完成交联固化反应;不放出低分子挥发性气体,因而可以制得无气隙的高性能结构复合材料。目前主要的A-型聚酰亚胺有NA酸酐封端的PMR聚酰亚胺、乙炔基封端的聚酰亚胺和双马来酰亚胺。本文仅就PMR聚酰亚胺在改性方  相似文献   

4.
非线性光学含氟PI/SiO2杂化波导纳米材料的研究   总被引:1,自引:0,他引:1  
以含氟的二胺5,5'-(六氟异丙基)-二-(2-氨基苯酚)及二酐4,4'-(六氟异丙基)-苯二酸酐为单体.首先合成了经酰胺化的主链上带有活性羟基的含氟聚酰亚胺,再通过Mitsunobu反应将活性生色分子分散红1共价链接到聚酰亚胺的侧链骨架上,合成了二阶非线性光学(NLO)含氟聚酰亚胺.采用溶胶-凝胶技术,利用偶联剂APTES制备带有发色团的及含有硅氧烷端分子的聚酰胺酸,其中的Si(OR)3基经水解、缩合后,与正硅酸乙酯在催化剂作用下反应,经杂化、凝胶后,得到热稳定性高的杂化材料.将制得的含氟聚酰亚胺/SiO2杂化材料,利用FT-IR、SEM、TEM、XRD、DSC等手段对其进行了表征.杂化材料的玻璃化转变温度(Tg)为382℃,比纯聚酰亚胺的Tg(306℃)高76℃,表现出优良的高温热稳定性.  相似文献   

5.
新型聚乳酸-聚酰亚胺嵌段共聚物的合成与表征   总被引:1,自引:0,他引:1  
用氨基封端的PEG-800(ATPEG)与均苯四甲酸酐(PMDA)共聚得到一种新型的氨基封端的可溶性聚酰亚胺(PI)。氨基封端的PI在辛酸亚锡(Sn(Oct)2)的催化作用下引发丙交酯开环共聚,形成聚乳酸-聚酰亚胺(PLA-PI-PLA)嵌段共聚物。采用傅里叶变换红外光谱(FT-IR)、核磁氢谱(1H NMR)、凝胶渗透色谱(GPC)、水接触角等对PI和PLA-PI-PLA进行了表征。FT-IR、1H NMR、GPC的结果表明成功合成了PI及PLA-PI-PLA。水接触角结果显示PLA-PI-PLA相对于聚乳酸亲疏水性明显改善,同时PI主链上的酰亚胺环能在一定的条件下发生开环反应,可提供修饰聚乳酸材料的活性位点。  相似文献   

6.
聚酰亚胺侧链功能化研究进展   总被引:1,自引:1,他引:0  
介绍了近年来在聚酰亚胺 (PI)侧链功能化研究方面所取得的进展。主要涉及新型含羟侧基聚酰亚胺的合成和PI OH/SiO2 杂化薄膜材料的制备 ;含联苯介晶基元侧链聚酰亚胺的合成 ;PI OH/SiO2 杂化薄膜中SiO2 含量和 /或偶联剂含量与微相结构、透明性、玻璃化转变温度 ,热稳定性、及力学性能之间关系 ;侧链液晶聚酰亚胺薄膜的聚集态结构、溶解性、玻璃化转变温度、热稳定性和力学性能  相似文献   

7.
通过苯乙烯和二乙烯基苯(DVB)自由基共聚方法合成了聚苯乙烯(PS)微球,并采用热交联方法对产物进行高温热处理,制备了耐热型聚苯乙烯微球。差示热分析和傅里叶红外光谱分析表明,热处理前DVB的添加量从5.5%增加到15%,其产物的玻璃化转变温度(Tg)基本保持在117℃左右不变;高温热处理使悬挂在聚合物分子链上的乙烯基双键发生自由基聚合交联反应,产物的交联密度提高,Tg明显提高,并且随着DVB添加量的增加Tg不断上升。产物热处理温度越高所需热处理时间越短,但是温度过高或时间过长,分子链会发生热降解副反应,导致Tg下降,较优的热处理条件为195℃时热处理1h。  相似文献   

8.
6FAPE基含氟聚酰亚胺的结构与性能研究   总被引:1,自引:0,他引:1  
利用含氟二胺单体4,4'-双(4-氨基-2-三氟甲基苯氧基)二苯醚(6FAPE),分别与1,2,3,4-环丁烷四酸二酐(CBDA)、3,3',4,4'-二苯醚四酸二酐(ODPA)、3,3',4,4'-联苯四酸二酐(BPDA)、3,3',4,4'-二苯甲酮四羧酸二酐(BTDA)和均苯四甲酸二酐(PMDA)进行低温缩聚反应,经热酰亚胺化制备出5种聚酰亚胺(PI)薄膜,考察了其光学透明性和热性能,研究了聚酰亚胺分子结构与性能的关系.结果表明,CBDA基含氟PI薄膜在可见光波长范围内(400~700nm)具有优异的光学透明性,450nm处的透光率为84.6%,且5种含氟PI薄膜在光通讯波段(1.30μm和1.55μm)均无明显吸收;除CBDA外,含氟PI薄膜均具有良好的热稳定性,5%热失重温度超过530℃;5种含氟PT薄膜的玻璃化转变温度Tg均在200℃以上,且CBDA基舍氟PI薄膜的Tg最高,达到265.5℃.  相似文献   

9.
采用流延法制备了聚酰亚胺(PI)薄膜,利用空间环境地面模拟设备,研究了空间环境中质子辐照对PI薄膜表面结构、化学组成和摩擦学性能的影响,探讨了质子辐照对材料的影响机理。结果表明:质子辐照导致PI分子链的结构发生了变化,PI薄膜表面发生了碳化反应,硬度与弹性模量显著提高,平均粗糙度降低。质子辐照改善了PI薄膜的摩擦磨损性能。  相似文献   

10.
塑料的高性能化已经成为当前研究的热点。选择耐水性优良的双酚A型二酐和双酚A型二胺作为反应单体,二步聚合得到分子量很高的端酸酐聚酰亚胺,利用酸酐的活性,接枝上酰基己内酰胺活性基团,聚合得到PI改性尼龙树脂,通过红外分析证明上述各步反应是成功的。聚酰亚胺(PI)改性尼龙的力学性能随着聚酰亚胺用量和分子量的增加而增加,明显优于一般工程塑料。微观分析聚酰亚胺分子并没有进入尼龙树脂的结晶相,而是形成致密的片晶存在尼龙基体中。  相似文献   

11.
The silica surface of immobilized artificial membranes containing phosphatidylcholine (IAM.PC) has approximately two aminopropyl groups per immobilized phosphatidylcholine molecule. Primary amines near the silica subsurface adsorb biomolecules and also decrease the chemical stability of IAM.PC surfaces. Consequently, subsurface amines were end-capped by several methods including silylating reagents, acetyl analogues, glycidol, methyl glycolate, short-chain anhydrides (3-6 carbons/anhydride chain), and long-chain anhydrides (10-12 carbons/anhydride chain). All end-capping reactions resulted in loss of the initially immobilized phosphatidylcholine molecule. However, the amount of PC loss during end capping was very low (for alkyl anhydride end-capping reactions) to very high (for silylation end-capping reactions). After end capping, IAM.PC showed increased chemical stability compared to non end-capped IAM.PC surfaces. The chemical stability of IAM packing material was monitored by phospholipid leaching from IAM surfaces exposed to organic and aqueous solvents using thin-layer chromatography, 1H NMR spectroscopy, infrared spectroscopy, and mass spectrometry. IAM.PC packing material end capped with long-chain anhydrides exhibited the greatest chemical stability, i.e., little or no detectable phospholipid leaching when challenged with aqueous and/or organic solvents. The chromatography of acidic and basic compounds on end-capped and non-end-capped IAM.PC surfaces was studied. Compared to non-end-capped IAM.PC HPLC columns, the chromatographic retention times of acidic compounds (deoxynucleotides) decreased after end capping. In contrast, the retention times of basic compounds (amphetamine analogues) increased on end-capped IAM.PC HPLC columns relative to non-end-capped IAM.PC HPLC columns. This indicates that these solutes have access to the silica subsurface amines during chromatography.  相似文献   

12.
可擦除式相变光盘研究   总被引:1,自引:0,他引:1  
姜复松  蒋模光 《功能材料》1993,24(4):306-310
本文综述了作者和各国研究人员对可擦除式相变光盘的研究成果。对如何提高可擦除式相变光盘记录材料在擦除速度、室温稳定性和写/擦循环次数等方面的性能提出了一系列看法。文中指出,在选择可擦除式相变光盘材料时,为了提高擦除速度,可引入T_q/T_m小的元素如Sb,Ag,Cu,Co,Pb等;为了提高室温稳定性,可引入T_g/Tm值小,T_g值高的元素,如Cu,Co等,为了提高写/擦循环次数,可在记录膜上加镀SiO_2界面膜和ZnS SiO_2混合保护膜。文中还列举了一些性能优良的可擦除式相变光6盘记录材料和保护膜,可供有关人员参考。  相似文献   

13.
Earlier studies conducted in the use of sealed tubes with polyalkylene glycol lubricants and polyethylene terephthalete (PET) films revealed that the PET films exhibited embrittlement and (visual) degradation. This led to an investigation of PET embrittlement mechanisms with the new lubricants used with HFC 134a. The lubricants studied were three polypropylene glycols (the monol, the diol and the completely end-capped glycols), pentaerythritol ester and a blend of monol and ester. The effects of moisture content, temperature and lubricant structure were studied. All lubricants in this study were of viscosity grade ISO-32 (150 SUS). The results were compared to PET film embrittlement in the presence of CFC 12 and mineral oil. This study reconfirmed the earlier findings that the PET films must be dried to lower than 0.1 wt.% moisture content for use in hermetic systems. This paper discusses the effect of the moisture content of the lubricant and the effect of the lubricant structure on PET films. The dependence of the various mechanisms on temperature is shown. Esters and end-capped polyalkylene glycols are recommended for use with HFC 134a.  相似文献   

14.
用密度泛函(DFT)方法在6-31G(d)基组优化了32种聚甲基丙烯酸酯类的结构单元,得到了其量子化学参数,用模式识别,逐步回归和人工神经网络方法探讨了这些参数与聚甲基丙烯酸酯类Tg的关系,模式识别两类Tg大小不同的聚合物基本分布在不同区域,用逐步回归和人工神经网络方法所建立的定量模型的计算值与实验值的相关系数分别为0.9760,0.9912,预报结果与实验值基本一致。  相似文献   

15.
Sputter-deposited FePt films exhibit an in-plane magnetic anisotropy when MgO is used as the capped layer. The perpendicular magnetic anisotropy of FePt films can be enhanced by introducing a Ag capped layer instead of a MgO capped layer. Although the in-plane coercivity (Hc//) of FePt films decreases slightly after introducing a Ag capped layer instead of a MgO capped layer, the perpendicular coercivity (Hc) is increased significantly from 3169 Oe to 6726 Oe. Auger electron spectroscopy analysis confirms that Ag atoms diffuse from the capped layer into the FePt magnetic layer and are mainly distributed at the grain boundary of FePt. This phenomenon results in enhancement of the grain boundary energy and inhibition of grain growth, thus increasing the perpendicular coercivity and reducing the grain size of the FePt film.  相似文献   

16.
盒式气调包装下温度对薄膜透气性能的影响   总被引:4,自引:3,他引:1  
以高阻隔膜、双层膜、聚丙烯(PP)膜及双向拉伸聚丙烯(BOPP)膜为材料,采用小袋法,分析了盒式气调包装下,各薄膜在4,10,25,30℃温度下的薄膜透气系数和透气系数比的变化规律。结果表明:随着温度的升高,4种薄膜的透气系数都呈上升趋势;同时,高阻隔膜和双层膜的透气系数比显著降低,而BOPP膜和PP膜的透气系数比则逐渐升高。同一温度条件下,PP膜的透气性能最好,BOPP膜次之,双层膜和高阻隔膜的透气性能较低。试验中,透气系数的自然对数与绝对温度的倒数满足阿累尼乌斯方程,以此可求得不同薄膜材料在其他温度下的透气系数。  相似文献   

17.
The effect of heat on the characteristics of chitosan film coated on theophylline tablets was studied. Chitosan of high viscosity grade with molecular weight in the range of 800,000-1,000,000, 80-85% degree of deacetylation was used as a film former by dissolving in 1% v/v acetic acid solution. The coated tablets had been cured at 40, 60, and 100°C for 6, 12, and 24 hr. The morphology of the film at the edge and surface of coated tablets was investigated using scanning electron microscopy. Film cracking was increased and clearly observed in the coated tablets cured at 100°C for 24 hr. As a result, more water could be absorbed into the tablets, followed by faster disintegration and faster drug release. The evidence of partial conversion of chitosonium acetate to chitin in the 13C nuclear magnetic resonance (NMR) spectra of chitosan films cured at 40, 60, and 100°C was observed, but it had no effect on drug release behavior. Theophylline tablets coated with chitosan films gave sustained release behavior in various media, i.e., distilled water, 0.1 N hydrochloric acid, pH 4.5 acetate buffer, and pH 6.8 phosphate buffer. In addition, the film coating temperature at 55-60°C and curing process at 40 and 60°C had no effect on the drug release from theophylline tablets coated with chitosan polymer. Finally, it might be concluded that both the physical and chemical properties of chitosan films were affected by heat.  相似文献   

18.
Friction tests were carried out using a microtribometer to investigate the effect of thermal treatment on microscale friction and wear between poly(methyl methacrylate) (PMMA) film and a fused silica lens. Two films were examined: one that was baked at 413 K for 2 min and one that was baked at 433 K for 24 h. The friction forces on the PMMA films were measured under atmospheric conditions as the temperature of the films was increased from 300 K to 443 K. The contact area between the films and the lens was also examined. As the temperature increased, the friction force increased for both films. The slope of the friction force with temperature and the contact area varied, depending on the state of the film surface; glassy, rubbery, and viscous flow states. The baking conditions also affected the slope, contact area, and wear generation. For temperatures at which the samples were in a glassy state, wear particles were not generated on the sample baked for 24 h. The results demonstrate that the tribological characteristics can be altered by the thermal treatment of the PMMA film as well as the temperature. When the film contains some residual solvent, the residual solvent in the PMMA film can diffuse to the PMMA surface due to heating and thus decrease the friction force under room-temperature conditions.  相似文献   

19.
硅生胶结构对补强硅橡胶的力学及加工性能的影响   总被引:2,自引:0,他引:2  
采用动态力学性能测试方法分析硅生胶分子结构对补强硅橡胶力学性能及加工性能的影响,并系统地研究了硅生胶复配体系对补强硅橡胶性能的影响.结果表明:乙烯基封端硅生胶结构规整,玻璃化转变温度Tg低,补强硅橡胶耐低温性好;硅生胶中乙烯基含量高,则补强硅橡胶的力学性能好;硅生胶分子量越高,补强硅橡胶的加工流动性越差;30份甲基封端和70份乙烯基封端的硅生胶复配体系中乙烯基含量为0.15%(质量分数)时,补强性能最佳.  相似文献   

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