Processable Aromatic Polyimides

Abajo, Javier de; Campa, José G. de la

doi:10.1007/3-540-49815-x_2

Cited by 216 publications

(64 citation statements)

References 105 publications

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“…However, their poor processability poses limitations to their use in practical applications 3. Considerable research efforts have been focused on the synthesis of soluble polyimides that maintain the excellent properties of this class of compounds 4. Typical approaches include the introduction of bulky lateral groups,5–12 flexible linkages,13, 14 kinked15–20 or unsymmetrical structures21, 22 into the polymer backbone.…”

Section: Introductionmentioning

confidence: 99%

Effect of a closure device on complication rates in high‐local‐risk patients: Results of a randomized multicenter trial

Chevalier

Lancelin

Köning

et al. 2003

Cathet Cardio Intervent

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Clinical trials have shown that coronary stenting is associated with a high level of complications at the access site. Arterial sealing devices have proven their efficacy in obtaining immediate hemostasis after sheath removal, in allowing early ambulation, and in improving patient comfort. However, there is no report showing a reduction of local complications related to their use. The purpose of this multicenter study was to compare randomly the efficacy of Angio-Seal versus compression methods of hemostasis in reducing the rate of access site complications after coronary angioplasty in 612 selected patients with higher risk of local events satisfying at least one of the following high-risk criteria: age> 70, previous puncture at the same site, history of hypertension, treatment with ticlopidine at least 2 days before the procedure, use of abciximab, 8 Fr access, prolonged heparin treatment after the angioplasty, and use of lytics if fibrinogen > 1 g/l. Group A (n = 306) had immediate sheath removal, Angio-Seal implantation, and cessation of bed rest 4 hr after the intervention. Group B (n = 306) had sheath removal according to local practice and cessation of bed rest 6-18 hr after the hemostasis procedure, also according to local practice. Clinical follow-up was done at 1 hr, 4 hr, 24 hr, discharge, and 7 days and a systematic color flow duplex sonography was performed to confirm diagnosis of access site complication. In group A, device deployment and immediate hemostasis were obtained in, respectively, 96.8% and 87% of patients. Time to hemostasis was shorter in group A: 5 vs. 52 min (P < 0.001). Cessation of bed rest was dramatically reduced in group A (438 +/- 450 min) vs. group B (952 +/- 308 min; P < 0.001). The cumulative rate of complications, using a composite primary endpoint, at 7 days was significantly different between the two groups: 5.9% of group A patients and 18% of group B patients (P < 0.001). This difference was mainly due to the dramatic reduction of prolonged bleeding in group A patients. Angio-Seal device use in high-local-risk patients allows immediate sheath removal and hemostasis with a reduction of local event rate despite a higher level of anticoagulation, compared to regular compression techniques, directly related to a dramatic decrease of prolonged bleeding.

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Section: Introductionmentioning

confidence: 99%

Effect of a closure device on complication rates in high‐local‐risk patients: Results of a randomized multicenter trial

Chevalier

Lancelin

Köning

et al. 2003

Cathet Cardio Intervent

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“…It has been known that copolymerization is a simple and effective way for structure modification to balance desired properties, such as melt processability, thermal stability and mechanical properties [14]. Therefore, a series of copolyimides based on mixed-TDPA were prepared on the basis of the structure-property relationships for the homopolyimides with the purpose of obtaining PIs with both nice melt-processability and a relative higher T g s. Table 4 summarizes the properties of copolyimides based on mixed-TDPA and several compositions of diamines.…”

Section: Mixed-tdpa-based Melt-processable Copolyimides 321 T G Ofmentioning

confidence: 99%

“…Moreover, the synthesis of TDPA is more convenient than that of ODPA [4]. Copolymerization by incorporating monomers with flexible moieties, which disrupts the regularity of molecular chain and prevents the interaction of polymer chains, is a simple but effective way for structure modification to balance the processability and the desired properties [14,15]. For example, 3,4'-oxydianiline (3,4'-ODA) has been proved to be a diamine with polyimide derivatives having better melt flowability than polymers from its isomer 4,4'-oxydianiline(4,4'-ODA) [16].…”

Section: Introductionmentioning

confidence: 99%

Melt processable homo- and copolyimides with high thermo-oxidative stability as derived from mixed thioetherdiphthalic anhydride isomers

Han¹,

Xz²,

Xx³

2010

Express Polym. Lett.

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Abstract.A series of homo-and copolyimides based on mixed thioetherdiphthalic anhydride isomers (mixed-TDPA) were synthesized with several kinds of aromatic diamines. The properties of these polyimides were characterized by glass transition temperature (Tg), thermal decomposition temperature, and melt processability. A series of copolyimides were prepared to achieve high Tg concurrently with melt processability by means of selecting appropriate diamines and their composition in the copolyimides. As a result, we obtained rheological information for a series of polyimide resins as a function of temperature, time and shear rate. It is found that the processability (e.g., melt viscosity of polyimides) and ultimate product properties (e.g., Tg of polyimides) can be systematically varied by changing the variety and composition of the aromatic diamines. It has been demonstrated that the incorporation of meta-or flexible diamines improve the melt processability of polyimides significantly. Meanwhile, Tg of copolyimides from dual-diamines can be predicted and regulated. Accordingly, copolyimides from 1,3-phenylenediamine (m-PDA) and 3,4'-oxydianiline (3,4'-ODA) were obtained with higher Tg and lower melt viscosity. Such correlations of chemical structures and rheological behavior provide the necessary database for tailor-making new polyimide systems with desirable processability and physical properties.

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“…29 Because of their highly tunable properties, these NC materials are evaluated for potential application in a large number of fields, such as those emphasizing mechanical performance and as polymer electrolytes. 34 Therefore, extensive efforts such as introducing of bulky pendent groups, flexible linkage, noncoplanar structures and or copolymerizing from different diamines or dianhydrides have been made to improve their processability. 31 Of thermally stable organic polymers, the excellent properties of aromatic PIs such as outstanding thermooxidative stability and higher chemical resistance led to the use of PIs in different area, such as insulating materials for electronics, semipermeable membranes for gas separation, and high-temperature adhesives and coatings.…”

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confidence: 99%

In situ thermal synthesis of novel polyimide nanocomposite films containing organo-modified layered double hydroxide: morphological, thermal and mechanical properties

2015

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An organic-inorganic hybrid compound constituted by a Zn/Al layered double hydroxide (LDH) intercalated with citric acid (LDH-CA), was dispersed in polyimides (PIs) with N-benzonitrile side group, through in situ polymerization. At first, 3-(bis(4-aminophenyl)amino)benzonitrile as a diamine monomer was synthesis and then it was reacted with 4,4′-benzophenone tetracarboxylicdianhydride via thermal imidization method to formed prossable PI. To improve the thermal and mechanical properties and also to avoid the aggregation of LDH particle in the polymer matrix, small amount of LDH-CA (1, 2, 4 wt %) was added to the synthesized PI. The resulted materials were characterized by Fourier transform-infrared spectroscopy, X-ray powder diffraction, thermogravimetry analysis (TGA), field emission-scanning electron microscopy, and transmission electron microscopy (TEM) techniques. TEM results showed that the LDH-CA nanolayers were dispersed in PI matrixes. The mechanical and thermal properties of the synthesized composites are effectively enhanced by the incorporation of 2wt.% LDH-CA in the polymer matrix. For the PI/LDH-CA nanocomposites, the maximum degree of tensile strength is observed at a LDH-CA loading of 2 wt%, corresponding to an almost 32% increase in tensile strength compared to the pure PI. IntroductionOrganic/inorganic hybrid materials have attracted widespread consideration owing to their potential uses as flame retardant materials, gene and drug delivery and catalyst carriers. 1 Polymeric nanocomposites (NCs) are a new class of materials consisting of nanosized fillers in a polymeric matrix, and possess properties superior to those of conventional microsized filler composites, due to the ultrafine dimensions of the filler. 2,3 Moreover, on account of the unique properties such as enhanced mechanical and thermal properties, reduced flammability as well as high chemical stability, polymer/layered crystal NCs have been recognized as one of the most important organic/inorganic hybrid materials. 4-6 Most of the published works has focused on organically modified smectite clays, in particular montmorillonites, as fillers of polymeric composites. 7-9 Furthermore, the emphasis is placed on layered double hydroxide (LDH) systems rather than clays in recent years due to artificially preparing and highly tunable properties. 10,11 LDHs are a kind of anion clay with unique properties that are not commonly observed in layered silicates. LDHs are well characterized and conventionally used for flame retardants, 12 catalysts, 13 ion exchangers, 14 matrices for biosensors, 15 and supercapacitor electrode material. 16 Their novelty originate from their broad range of chemical composition, highly tunable properties, ease of synthetic procedures in the laboratory, stability in air, interchangeable anions and their potential industrial uses. 17 Ultrathin nanosheets, prepared by delamination of layered hydroxides, have attracted attention due to the extremely small thickness of the order of 1 nm and large lateral size of the order...

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Processable Aromatic Polyimides

Cited by 216 publications

References 105 publications

Effect of a closure device on complication rates in high‐local‐risk patients: Results of a randomized multicenter trial

Effect of a closure device on complication rates in high‐local‐risk patients: Results of a randomized multicenter trial

Melt processable homo- and copolyimides with high thermo-oxidative stability as derived from mixed thioetherdiphthalic anhydride isomers

In situ thermal synthesis of novel polyimide nanocomposite films containing organo-modified layered double hydroxide: morphological, thermal and mechanical properties

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