明胶改性聚酰胺酸薄膜的化学亚胺化

采用化学脱水剂对明胶改性聚酰胺酸薄膜进行不同时间的化学亚胺化.通过红外光谱、示差扫描量热、热重分析等手段对化学亚胺化过程中薄膜的业胺化程度、热性能和力学性能进行了测定.结果表明,在化学亚胺化初期,薄膜的亚胺化程度、玻璃化温度和拉伸强度随着化学亚胺化时间的延长而增加.当化学亚胺化时间超过12 h后,继续延长化学亚胺化时间,薄膜的亚胺化程度、玻璃化温度和拉伸强度基本不变,薄膜的化学亚胺化基本完成.这时可得到玻璃化温度为205 ℃左右、耐520 ℃高温、拉伸强度较高的薄膜.     

聚酰胺酸薄膜表面热亚胺化动力学研究

采用均苯四甲酸二酐(PMDA)与4,4’-二氨基二苯醚(ODA)为单体,聚合得到表观黏度为1800m Pa·s的聚酰胺酸(PAA);通过衰减全发射红外光谱(ATR-FTIR)对聚酰胺酸凝胶膜表面亚胺化动力学进行了研究,结果表明:亚胺化程度随时间的增加和温度的升高而增大,并出现初期的快速和后期的慢速两个阶段。此外,由于薄膜下表面含有较多的残留溶剂,使其酰亚胺化程度高于上表面。用两步一级动力学模型进行关联,得到了相关的动力学参数。     

聚酰胺酸粒子亚胺化的研究

以均苯四酸二酐(PMDA)和4,4,-二氨基二苯醚(ODA)为原料合成了均苯型的聚酰胺酸(PAA)粒子.并以乙酸酐/吡啶为脱水剂,对PAA粒子进行化学亚胺化和不同温度下进行热亚胺化处理.通过红外光谱(IR),紫外光谱(UV),示差热量扫描(DSC)探讨了PAA的亚胺化条件.     

聚酰胺酸薄膜热环化过程热分析

用差热扫描量热仪(DSC)和傅立叶红外光谱仪(FTIR),考察了梯度升温过程中聚酰胺酸PAA[由4,4-二胺基二苯醚(ODA)和3,3,4,4-二苯醚四酸二酐(ODPA)制备]薄膜环化度和玻璃化温度(Tg)随反应温度的变化。结果表明,随着温度的升高,聚合物薄膜的亚胺化程度和Tg不断增大,且各恒温点的薄膜Tg均高于反应温度。另外,由亚胺化程度与Tg的关系曲线可见,在环化程度低时,薄膜Tg增长缓慢;随着亚胺化程度继续增高,薄膜的Tg迅速增大。用热环化过程中分子活动性的变化解释了酰亚胺化反应过程中环化速率的变化。     

不同亚胺化温度对聚酰亚胺无纺布膜性能的影响

本文以聚酰亚胺酸（PAA）为纺丝液,采用高压静电纺丝技术制备了醚酐型（ODPA—ODA型）PAA无纺布,通过不同的亚胺化温度获得ODPA—ODA型聚酰亚胺（PJ）无纺布。利用红外光谱仪、扫描电子显微镜和电子万能试验拉伸机研究了不同亚胺化温度对PI无纺布性能的影响。结果表明：当亚胺化温度为250℃时,聚酰胺酸只是部分发生了亚胺化;亚胺化温度为300℃,聚酰胺酸开始完全亚胺化成为聚酰亚胺,同时,聚酰亚胺纤维出现了不同程度的收缩、弯曲和交联;当亚胺化温度从2500（2升高到300℃时,PI无纺布薄膜的拉伸强度由4．92MPa提高到7．76MPa,断裂伸长率从11．3％增加到29．5％。     

化学亚胺化法聚酰亚胺材料的制备及性能研究

以对-亚苯基-双苯偏三酸酯二酐和4,4′-二氨基二苯醚为单体,乙酸酐和三乙胺为化学亚胺化试剂,通过改变亚胺化试剂的含量制备了一系列聚酰亚胺(PI)薄膜,并对薄膜的微观结构及性能进行了研究。研究结果表明,随着亚胺化试剂添加量的增加,聚酰胺酸脱水生成PI的反应程度逐渐增大,在后续薄膜成形过程中更有利于溶剂脱除,但是对最终PI的一级化学结构并没有影响。然而,亚胺化试剂的加入提高了最终PI薄膜的结晶度,同时改善了无定形区分子链段堆砌,使PI薄膜的玻璃化转变温度上升,热膨胀系数降低。     

PA封端型聚酰亚胺的合成与表征

以均苯四甲酸二酐(PMDA)和自制的1,3-双(4-氨基苯氧基)苯(TPER)在邻苯二甲酸酐(PA)封端的情况下溶液缩聚得到聚酰胺酸(PAA),通过溶液亚胺化和固相亚胺化相结合得到聚酰亚胺(PI).用傅立叶变换红外光谱仪、乌氏粘度计和热失重分析仪对PI进行了结构表征和性能测试,分析了封端剂加入量、亚胺化方式对PI性能的影响.结果表明,封端剂的加入可有效降低PI的粘度,两种亚胺化方式的结合可以降低PI的最终亚胺化温度,得到的PI热稳定性高.     

共聚型聚酰亚胺热亚胺化动力学研究

为考察共聚体系的热亚胺化动力学,今以4,4’-二氨基二苯醚(ODA),均苯二酐(PMDA),3,3’,4,4’-二苯酮二酐(BTDA)为单体合成共聚型聚酰胺酸(PAA),通过差示扫描量热分析(DSC)法测量PAA亚胺化动力学,并通过红外光谱分析仪 FT-IR 分析聚酰亚胺(PI)亚胺化程度,万能试验机测试共聚物力学性能.结果表明:随着柔性二酐(BTDA)的引入,聚合物分子链柔性增强,DSC图谱上反应出亚胺化反应相对平缓.动力学数据显示,二酐共聚体系亚胺化反应活化能最小,端基间碰撞克服的能垒最低,有利于亚胺化的进行.     

聚酰亚胺薄膜及纤维的探索研究

利用均苯四甲酸二酐(PMDA)、4,4'-二氨基二苯醚(4,4'-ODA)和自制三单体在强极性非质子有机溶剂N,N-二甲基乙酰胺(DMAc)中进行共缩聚反应,制得高粘度的聚酰胺酸(PAA)溶液,经涂膜、热亚胺化,得到坚韧透明的聚酰亚胺(PI)薄膜,其具有较好的拉伸断裂强度和合适的伸长率;同时将得到的PAA溶液进行湿法纺丝,制成PAA纤维,采用热亚胺化和高温拉伸的方法制得PI纤维,其断裂强度能达到3.67cN/dtex。     

尿素氯化胆碱低共熔溶剂催化聚酰胺酸亚胺化研究

研究了均苯四甲酸二酐（PMDA）和4，4，-二氨基二苯醚（ODA）为单体制取聚酰亚胺（PI）的清洁过程。首先在N,N-二甲基甲酰胺（DMF）中获得聚酰胺酸（PAA）。之后，以尿素-氯化胆碱低共熔溶剂（DES）为化学酰亚胺化催化剂，乙酸酐为脱水剂，协同实现PAA亚胺化。所得产物PI可通过简单过滤分离。用FTIR、TGA-DSC和元素分析等对PAA和PI的结构进行表征。同时考察了反应时间、反应温度、DES催化剂与脱水剂用量等对PAA亚胺化反应的影响。得到亚胺化最佳反应条件为：温度80 ℃，DES与乙酸酐体积比1：2、PAA与DES物质的量比1：2，在该条件下制备的样品，其热重和红外光谱分析结果证实了亚胺键的生成。此外，DES 和DMF可重复使用，过程绿色不使用有毒有害的吡啶、咪唑和喹啉类催化剂。     

Effect of film formation process on residual stress of poly(p-phenylene biphenyltetracarboximide) in thin films

Soluble poly(p-phenylene biphenyltetracarboxamine acid) (BPDA-PDA PAA) precursor, which was synthesized from biphenyltetracarboxylic dianhydride and p-phenylene diamine in N-methyl-2-pyrrolidone (NMP), was spin-cast on silicon substrates, followed by softbake at various conditions over 80–185°C. Softbaked films were converted in nitrogen atmosphere to be the polyimide films of ca. 10 μm thickness through various imidizations over 120–400°C. Residual stress, which is generated at the polymer/substrate interface by volume shrinkage, polymer chain ordering, thermal history, and differences between properties of the polymer film and the substrate, was measured in situ during softbake and subsequent imidization processes. Polymer films imidized were further characterized in the aspect of polymer chain orientation by prism coupling and X-ray diffraction. Residual stress in the polyimide film was very sensitive to all the film formation process parameters, such as softbake temperature and time, imidization temperature, imidization step, heating rate, and film thickness, but insensitive to the cooling process. Softbaked precursor films revealed 9–42 MPa at room temperature, depending on the softbake temperature and time. That is, residual stress in the precursor film was affected by the amount of residual solvent and by partial imidization possibly occurring during softbake above the onset of imidization temperature, ca. 130°C. A lower amount of residual solvent caused higher stress in the precursor film, whereas a higher degree of imidization led to lower stress. Partially imidized precursor films were converted to polyimide films revealing relatively high stresses. After imidization, polyimide films exhibited a wide range of residual stress, 4–43 MPa at room temperature, depending on the histories of softbake and imidization. Relatively high stresses were observed in the polyimide films which were prepared from softbaked films partially imidized and by rapid imidization process with a high heating rate. The residual stress in films is an in-plane characteristic so that it is sensitive to the degree of in-plane chain orientation in addition to the thermal history term. Low stress films exhibited higher degree of in-plane chain orientation. Thus, residual stress in the film would be controlled by the alignment of polyimide chains via the film formation process with varying process parameters. Conclusively, in order to minimize residual stress and to maximize in-plane chain orientation, precursor films should be softbaked for 30 min-2 h below the onset imidization temperature, ca. 130°C, and subsequently imidized over the range of 300–400°C for 1–4 h by a two-step or multi-step process with a heating rate of ? 5.0 K min⁻¹, including a step to cover the boiling point, 202°C, of NMP. In addition, the final thickness of the imidized films should be <20 μm. © 1997 Elsevier Science Ltd.     

Effects of thermal imidization on mechanical properties of poly(amide‐co‐imide)/multiwalled carbon nanotube composite films

In this study, experimental and numerical studies were performed to investigate the relationship among the functionalization method, weight fraction of MWCNTs, thermal imidization cycle, and mechanical properties of various PAI/MWCNT composite films. Poly(amide‐co‐imide)/multiwalled carbon nanotube composite films were prepared by solution mixing and film casting. The effects of chemical functionalization and weight fraction of multiwalled carbon nanotubes on thermal imidization and mechanical properties were investigated through experimental and numerical studies. The time needed to achieve sufficient thermal imidization was reduced with increasing multiwalled carbon nanotube content when compared with that of a pure poly(amide‐co‐imide) film because multiwalled carbon nanotubes have a higher thermal conductivity than pure poly(amide‐co‐imide) resin. Mechanical properties of pure poly(amide‐co‐imide) and poly(amide‐co‐imide)/multiwalled carbon nanotube composite films were increased with increasing imidization time and were improved significantly in the case of the composite film filled with hydrogen peroxide treated multiwalled carbon nanotubes. Both the tensile strength and strain to failure of the multiwalled carbon nanotube filled poly(amide‐co‐imide) film were increased substantially because multiwalled carbon nanotube dispersion was improved and covalent bonding was formed between multiwalled carbon nanotubes and poly(amide‐co‐imide) molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚酰胺酸酰亚胺化条件及其对聚酰亚胺力学性能的影响

采用均苯四酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)为单体,N-甲基吡咯烷酮(NMP)为溶剂,合成了黏度为1.87 dL/g的聚酰胺酸(PAA)。对聚酰胺酸分别进行了热酰亚胺化和化学酰亚胺化处理,研究了完全酰亚胺化所需的条件以及不同酰亚胺化方式对聚酰亚胺(PI)纤维条断裂强度的影响;对PAA初生纤维条进行拉伸和酰亚胺化处理的顺序不同,所得到的聚酰亚胺(PI)纤维条的力学性能不同,采用先酰亚胺化再拉伸的方法能得到力学性能更优异的聚酰亚胺(PI)纤维条。     

电位滴定法测定聚酰胺酸固相热环化动力学

针对二步法合成聚酰亚胺的固相热环化过程,采用改进的自动电位滴定法和GPC测定了反应的剩余聚酰胺酸含量及相对分子质量随反应时间及反应温度的变化。结果表明:聚合物平均相对分子质量随热处理时间和温度的增加而逐步增大,相对分子质量分布指数则呈现先增后降的变化趋势。聚合物剩余聚酰胺酸的质量分数随热处理时间增加而逐渐降低,并出现初期的快速和后期的慢速2个阶段。提高热处理温度,则环化速率明显增大,环化程度亦增大。采用两步一级动力学模型关联并得到了2个阶段的热环化动力学参数,快速和慢速阶段的活化能较为接近,而指前因子和过渡熵相差较大。     

聚酰亚胺纤维的制备及其结构研究

将均苯四甲酸二酐(PMDA)和4,4’-二氨基二苯醚(ODA)在N-甲基吡咯烷酮(NMP)中进行溶液聚合得到聚酰胺酸(PAA)溶液,并用该溶液进行干湿法纺丝得到PAA纤维,分别用化学酰亚胺化法和热酰亚胺化法得到聚酰亚胺(PI)纤维。研究了凝固浴组成和工艺条件对PAA形态结构和纤维性能的影响,以及不同酰亚胺化方法对PI纤维形态结构和性能的影响。结果表明:以甲醇为凝固浴制备的PAA初生纤维,无孔致密,最高拉伸强度和初始模量分别为2．21 cN/dtex和40．73 cN/dtex;采用化学酰亚胺化法制得的PI纤维中存在少许孔洞缺陷,其强度较低,热酰亚胺化法制得的PI纤维无孔致密,其强度和模量分别达到2．83 cN/ dtex和43．4 cN/dtex。     

Effect of thermal history during drying and curing process on the chain orientation of rod-shaped polyimide

Chain orientation in polyimide (PI) film is influenced by the thermal history during drying and curing process. The amount of residual solvent and the degree of imidization, among other factors, play a major role in determining the chain orientation during the process. In the present study, poly(amic acid), the precursor of PI, coated on the glass substrate was imidized to PI through different drying and curing protocols. On the way of complete imidization, the residual solvent concentration and the degree of imidization were characterized using confocal Raman spectroscopy. The poly(amic acid) began to imidize quickly while retaining more solvent in the film as the initial drying temperature increased. The degree of in-plane chain orientation in fully imidized PI film made by different process protocols was compared using polarized Raman spectroscopy. The fully imidized PI showed the lowest degree of in-plane chain orientation when it was processed by the protocol with the highest drying temperature. The difference in the degree of in-plane chain orientation among different PI films significantly influenced the in-plane thermal expansion coefficient, while no significant change in crystallinity or glass transition temperature was observed.     

聚砜酰胺酸和聚砜酰亚胺的微波辐射合成

采用4，4'-二氨基二苯砜(DDS)与均苯四酸二酐(PMDA)为单体进行微波辐射溶液聚合反应，所得的聚酰胺酸进行固相微波辐射亚酰化。考察了微波辐射时间、反应温度、单体浓度、单体配比等因素对聚合物的特性粘数、转化率的影响，并与热聚合进行比较，用红外及核磁共振的测试方法对聚合物的结构进行了表征，通过红外光谱表征了聚酰亚胺的亚酰化度。实验结果表明：微波辐射不仅能缩短缩聚反应时间，还能提高缩聚物的特性粘数和转化率。固相微波辐射使聚酰胺酸的亚酰化时间缩短，亚酰化度增大。合成的聚酰胺酸和聚酰亚胺都具有一定的荧光性能，聚酰亚胺具有一定的磁性。