高分子高温无润滑轴承材料

本发明涉及一种用于制造工业输送辊道中的高分子高温无润滑轴承材料。其特征在于：是由高温树脂、固体润滑剂、碳纤维复合成聚酰亚胺复合材料,合成聚酰亚胺有六组配方;其工艺过程为：首先按上述配方合成聚酰胺酸液：将上述六组配方均在乙醇溶液中反应,按下面步骤完成：①开环加成,成聚酰胺酸：②加入固体润滑剂和碳纤维,混合均匀;③环化脱水、干燥、研成粉末状聚酰亚胺复合粉。     

“黄金膜”——聚酰亚胺薄膜在深圳生产

聚酰亚胺薄膜是由均苯四甲酸二酐与4,4＇-二氨基二苯醚在强极性溶剂(二甲基乙酰胺)中,于低于50℃的条件下,合成高分子量的聚酰胺酸,再经高温(300～500℃)脱水酰亚胺化并加工成膜制得。1961年由美     

均苯型聚酰亚胺的合成与性能研究

采用均苯四甲酸二酐和4,4'-二胺基二苯醚合成均苯型聚酰亚胺,考察了两步法合成聚酰亚胺过程中单体摩尔比、加料顺序、反应温度、反应时间对聚酰胺酸溶液粘度的影响,得到了中间体聚酰胺酸的最佳合成条件为,采用正加料法,单体PMDA/ODA摩尔配比为1.02∶1,反应温度为20℃,反应时间为3h,聚酰亚胺的热分解温度为594℃,玻璃化温度为247℃.     

含噁唑环均苯型聚酰亚胺的制备和表征

为了提高聚酰亚胺材(PI)料的耐热性能,以2,6-二(对氨基苯)苯并[1,2-d;5,4-d]二噁唑为单体,采用两步法与均苯四甲酸二酐(PMDA)合成出了新型聚酰亚胺薄膜.采用红外光谱、热分析等手段对其结构与性能进行了表征.测定了聚酰亚胺的预聚体-聚酰胺酸(PAA)的特性黏度达到1.18dL/g,玻璃化温度343℃,在空气中热失重温度为626℃,表现出优异的热氧化稳定性.评价了聚酰亚胺在各种溶剂中的溶解性能,均不溶于常规的极性溶剂,甚至在浓硫酸中也不溶解.经红外光谱测定,聚酰胺酸基本转化成聚酰亚胺.     

共缩聚聚酰胺酸和聚酰亚胺的微波辐射合成研究

在N,N′-二甲基甲酰胺(DMF)溶剂中,选用3,3,′4,4′-二苯酮四羧酸二酐(BTDA)、均苯四甲酸酐(PMDA)和4,4′-二氨基二苯醚(ODA)为单体,微波辐射低温溶液缩聚合成一种共缩聚聚酰亚胺的前驱体聚酰胺酸(PAA),然后亚胺化脱水环化生成共缩聚聚酰亚胺(PI)。通过特性黏数([η])、红外光谱(FT-IR)和热重分析(TGA)对聚合物进行了结构表征和性能测试。结果表明,微波辐射溶液聚合能够提高PAA的特性黏数及产率,微波的引入大大缩短了反应时间;IR表明,在1778 cm-1和1723 cm-1处观察到聚酰亚胺特征峰;TG表明,PI在氮气中535℃左右开始降解,10%热失重温度(Td10%)为587℃。     

微波辐射合成聚酰胺酸和聚酰亚胺的研究

在N,N’-二甲基甲酰胺溶剂中,以均苯四甲酸酐和3,3’,4,4’-二苯酮四羧酸二酐为二酐单体,4,4’-二氨基二苯醚和4,4’-二氨基二苯甲烷为二胺单体,采用微波辐射低温溶液共缩聚,合成了聚酰胺酸(PAA)预聚体,然后亚胺化脱水、环化,生成共缩聚聚酰亚胺(PI)。通过红外光谱(FT-IR)、特性粘度[η]和热重分析(TG)等对聚合物进行了一系列的结构表征和性能测试。结果表明,微波辐射溶液聚合能够提高PAA的特性粘数及产率,微波的引入大大缩短了反应时间;FT-IR表明,在1 775 cm-1和1 724 cm-1处观察到聚酰亚胺特征峰;TG表明,PI的5%热失重温度(Td5%)为477℃,10%热失重温度(Td10%)为553℃。     

含噁唑环支链的苯氧型共聚聚酰亚胺的合成与表征

以3,5-二硝基苯甲酰氯和邻氨基苯酚为原料合成了含苯并噁唑基团的二胺,然后将其与二氨基二苯醚(ODA)和二苯醚四甲酸二酐(ODPA)进行常温共聚合成聚酰胺酸,最后采用两步法合成了含苯并噁唑支链的可溶性聚酰亚胺(PI)。采用红外光谱(FT-IR)、差示扫描量热法(DSC)和热重分析(TGA)等测试手段分析了该PI的结构、热性能和在各溶剂中的溶解性能。实验结果表明,经300℃热处理1h后,聚酰胺酸转化为酰亚胺化比较完全;引入苯并噁唑支链基团可以提高PI的耐热性,其玻璃化转变温度(Tg)在300℃左右,初始热分解温度为552.5℃;该PI在强极性溶剂中溶解性能良好,但不溶于一般的极性溶剂中,说明其在提高加工性能的同时仍能保持耐一般溶剂的性能。     

聚酰亚胺热处理过程中的结构化和层压板力学性能

本文用动态力学扭辫分析(TBA),差示扫描量热法(DSC)及热失重法(TG)研究聚酰胺酸热处理过程中结构转化,并对聚酰亚胺层压板室温、高温抗弯强度,抗冲强度作了对比。结果表明TBA法能测定聚酰胺酸热处理过程中的结构转化,包括聚酰胺酸亚胺化反应,聚酰亚胺玻璃化转化及交联分解反应等。热处理温度是影响聚酰胺酸结构转化和力学性能的主要因素,于360～400℃处理后聚酰亚胺产生了不可逆反应,使玻璃化温度Tg由272℃提高到285～300℃,抗弯、抗冲强度也显著提高。进一步提高温度聚酰亚胺发生交联,分解反应其起始分解温度由419℃提高到464℃。     

含嗯唑环支链的苯氧型共聚聚酰亚胺的合成与表征

以3,5-二硝基苯甲酰氯和邻氨基苯酚为原料合成了含苯并嗯唑基团的二胺,然后将其与二氨基二苯醚（ODA）和二苯醚四甲酸二酐（ODPA）进行常温共聚合成聚酰胺酸,最后采用两步法合成了含苯并嗯唑支链的可溶性聚酰亚胺（PI）。采用红外光谱（FT—IR）、差示扫描量热法（DSC）和热重分析（TGA）等测试手段分析了该PI的结构、热性能和在各溶剂中的溶解性能。实验结果表明,经300℃热处理1h后,聚酰胺酸转化为酰亚胺化比较完全;引入苯并嗯唑支链基团可以提高PI的耐热性,其玻璃化转变温度（L）在300℃左右,初始热分解温度为552．5℃;该PI在强极性溶剂中溶解性能良好,但不溶于一般的极性溶剂中,说明其在提高加工性能的同时仍能保持耐一般溶剂的性能。     

长链聚酰亚胺的制备与表征

以长链二胺4,4' 二(4 氨基苯氧基)二苯砜(BAPS)为单体,采用两步法分别与二酐PMDA、ODPA、BPADA合成了3种链长的聚酰亚胺。实验利用GPC监测0 05mol/L聚酰胺酸(PAA)的数均聚合度(Xn)及相对分子质量分布随缩聚时间的变化关系,结果表明该反应为一逐步缩聚反应,缩聚速率随二酐电子亲和性(EA)的递增而增加;与预聚体聚酰胺酸相比,热处理环化得到聚酰亚胺其数均分子质量( Mn)和特性粘度[η]均有所下降,而分布指数(D)增大。此外还利用红外光谱(FTIR)、差分扫描量热法(DSC)、热重分析(TGA)等对聚酰亚胺进行了表征,结果表明聚酰亚胺(PI)的玻璃化温度(tg)和热分解温度(td)随着聚合单元长度的增加而降低。     

Synthesis and characterization of polyimides by use of metal salts and phosphorous compounds in the presence of solvent

Polyimide precursors and polyamic acid were synthesized by direct polycondensation reaction of the 1,2,3,4-butanetetracarboxylic acid (BTCA) and diamines in the presence of metal salts and phosphorous compounds. The BTCA was reacted with an initiating species, which is the phosphonium salt of metal salts and phosphorous compounds, to form acyloxy phosphonium salt building up at moderated temperatures. The salt reacts with diamine to form polyamic acid. The reaction was markedly affected by several factors: reaction temperature and time, solvent, metal salts phosphorous compounds, and tertiary amine. The polyamic acid was converted into polyimide by chemico-thermal or thermal methods. The polyimide with a high molecular weight can be prepared from BTCA and diamines and was soluble in polar aprotic solvent. © 1996 John Wiley & Sons, Inc.     

Preparation of polyimide powder

A polyimide powder was prepared from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA). Polyimide powder having low molecular weight was prepared by imidizing low-molecular-weight polyamic acid. The molecular weight of this polyimide powder increased on heating in a solid state. The molecular weight increased with the decrease of crystallinity of polyimide. © 1996 John Wiley & Sons, Inc.     

Adhesion and interface studies between copper and polyimide

The adhesion and interface structure between copper and polyimide have been studied. Polyimide films were prepared by spinning a polyamic acid solution (Du Pont PMDA-ODA) in an NMP solvent onto a Cu foil, followed by thermal curing up to 400°C. The adhesion strength was measured by a 90° peel test. The peel strength of 25 μm thick Cu foil to 25 μm thick polyimide substrate was about 73 g/mm with the peel strength decreasing with increasing polyimide thickness. Cross-sectional TEM observation revealed very fine Cu-rich particles distributed in the polyimide. Particles were not found closer than 80-200 nm from Cu boundary. These Cu-rich particles were formed as a result of reaction of polyamic acid with Cu during thermal curing. We attribute the high peel strength to interfacial chemical bonding between Cu and polyimide. This behavior is in contrast to vacuum-deposited Cu onto fully cured polyimide.     

Positive photosensitive polyimides using polyamic acid esters with phenol moieties

Polyimide resists developable with basic aqueous solutions were realized by polyamic acid esters with phenol moieties (PPh's) and naphthoquinone diazides. The polyimide precursors (PPh's) were synthesized from diamines and dicarboxylic acids that have phenol moieties through ester linkage. A selective reaction of alcohol groups with acid dianhydride groups made the synthesis of the PPh's possible, even if the phenol groups were in the reaction mixtures. The PPh's were soluble in basic aqueous developer, but their dissolution rates were too low for use as resists. To increase the resist dissolution rate, polyamic acids were added to the PPh's. By adjusting the dissolution rates in basic aqueous developers, fine patterns could be realized. The polyimide resists had high thermal stability and reliable adhesive property to silicon substrate. © 1994 John Wiley & Sons, Inc.     

Fibers from a soluble,fluorinated polyimide

Polyimide fibers have been produced from both polyamic acid and polyimide resins, derived from 2, 2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 2, 2-bis (4-4-aminophenoxy) phenyl) hexafluoropropane, by extrusion into various aqueous organic media. Polyimide fibers obtained from polyamic acid fibers after thermal imidization exhibited round or oval cross-sections, while fibers obtained directly from a polyimide resin had dogbone, C-shaped, or oval cross-sections. The effect of polymer inherent viscosity and filament production parameters on the formation of macropores within the filament will be discussed. Tensile properties of fibers, produced under various conditions, are listed and compared. © 1993 John Wiley & Sons, Inc.     

Physicochemical characterization of alloy of polyimide with varying degree of crosslinking through diisocyanates

Polyimide alloys are prepared by blending the crosslinked and uncrosslinked polyamic acid components and followed by thermal imidization. The blend components can be synthesized by the reaction of polyamic acid with the varying concentration of crosslinker [here methylene bis (4-phenyl isocyanate or MDI)] from 1.54 × 10^?2 mol/L (i.e. hypothetically calculated critical crosslinker concentration or CCC) to 1.54 × 10^?6 mol/L. This communication discusses the synthesis and characterization of polyimide (PI) blends and alloys prepared by varying degrees of crosslinking introduced via isocyanate-amic acid reaction. The polyimides were prepared by thermally imidizing the polyamic acid blends at different curing temperatures from 50°C to 350°C. The degree of imidization and residual solvent content for blends having varying mole fractions of crosslinked (or branched) and uncrosslinked components and two extreme conditions and at specified temperature-time profiles have been studied. The resultant PI-MDI blends have exhibited synergism on mechanical properties. The improvement in mechanical properties, however, was significantly higher at the lower imidization temperature (i.e. 50°C to 150°C). The feasibility of preparing polyimide alloys with synergistic combinations of crosslinked and uncrosslinked polyimide components was inferred.     

Morphology and size control of inorganic particles in polyimide hybrids by using SiO2-TiO2 mixed oxide

Polyimide/inorganic hybrids were prepared by sol-gel reaction starting from tetraethoxysilane (TEOS), and tetrabutyl titanate (TBT) in the solution of polyamic acid in N,N-dimethylformamide. The hybrid films were obtained by the hydrolysis-polycondensation of TEOS and TBT in polyamic acid solution, followed by the elimination of solvents and imidization process. Binary polyimide/SiO₂ and polyimide/TiO₂ hybrids, as well as ternary polyimide/SiO₂-TiO₂ hybrids (with varied ratio of SiO₂ to TiO₂) were prepared to study the effects of the recipes and inorganic components on the morphologies of the polyimide hybrids. Transparent films with much higher inorganic content can be obtained in ternary polyimide hybrids, while lower inorganic content in binary hybrids. The results also indicate that the inorganic particles are much smaller in the ternary systems than in the binary systems, the shape of the inorganic particles and the compatibility for polyimide and inorganic moieties are varied with the ratio of the inorganic moieties in the hybrids. The completely imidization temperature of the polyamic acid was delayed, and furthermore, the thermal stability of polyimide was enhanced through the incorporation of the inorganic moieties in the hybrid materials.     

Thermal analysis and its application in evaluation of fluorinated polyimide membranes for gas separation

Seven polyimides based on (4,4′-hexafluoroisopropylidene) diphthalic anhydride, 6FDA, with different chemical structures were synthesized in a single pot two-step procedure by first producing a high molecular weight polyamic acid (PAA), followed by reaction with acetic anhydride to produce polyimide (PI). The resulting polymers were characterized using thermal analysis techniques including TGA, derivative weight analysis, TGA–MS, and DSC. The decarboxylation-induced thermal cross-linking, ester cross-linking through a diol, and ion-exchange reactions of selected polyimide membranes were investigated. Cross-linking of polymer membranes was confirmed by solubility tests and CO₂ permeability measurements. The thermal analysis provides simple and timesaving opportunities to characterize the polymer properties, the ability to optimize polymer cross-linking conditions, and to monitor polymer functionalization to develop high performance polymeric membranes for gas separations.     

含苯炔基侧链的聚酰亚胺树脂及其复合材料

采用联苯酐(3,4′-BPDA)与4,4′-二氨基二苯醚(4,4-ODA),3,5-二氨基-4′-苯炔基二苯甲酮(DPEB),苯炔基苯酐(PEPA)制备了不同分子质量的聚酰亚胺树脂。通过流变分析,热重分析,红外光谱,动态热力学分析及静态力学性能测试等研究了分子结构,分子质量等因素对聚酰亚胺树脂耐热性和力学性能的影响。结果表明,合成的聚酰亚胺树脂具有优异耐热性能和较高的韧性,固化后树脂的玻璃化转变温度为379℃,5%热失重温度高于550℃,并且浇注体的拉伸强度是61 MPa,断裂伸长率是6.2%.碳纤维复合材料的室温弯曲强度为1 850 MPa,层间剪切强度为84 MPa,316℃时弯曲强度为946 MPa,剪切强度为46 MPa,具有良好的高温力学保持率。     

Polyimide blend alignment layers for control of liquid crystal pretilt angle through baking

Polyimide films were used for liquid crystal (LC) alignment layers to control LC pretilt angles over the full range (8°-90°). The pretilt angles could be controlled using polyimide films prepared from polyamic acid for vertical LC alignment and using polyimide blend films prepared from two types of polyamic acids, one for vertical LC alignment and the other for planar LC alignment, by changing the baking times ranging from 40 to 180 min at 230 °C. The polyimide blend film could control the pretilt angle better than the polyimide prepared from just one polymer component. The LC alignment behavior was well correlated with the wettability of the polyimide films due to the fragmentation of the long alkyl side group on the polyimide surfaces by the baking process.