On the evidence of crosslinking in methyl pendent PBZT fiber

Mehta, Vinay R.; Kumar, Satish; Polk, Malcolm B.; VanderHart, David L.; Arnold, F. E.; Dang, Thuy D.

doi:10.1002/(sici)1099-0488(199608)34:11<1881::aid-polb5>3.0.co;2-v

Cited by 16 publications

(5 citation statements)

References 2 publications

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“…Lack of solubility has generally been used as conclusive evidence of crosslinking in rigid‐rod polymers. However, work done on methyl‐pendant PBZT (MePBZT) fibers has shown insolubility to be inconclusive in demonstrating the presence of crosslinking 217. As‐spun MePBZT fibers are soluble in methane sulfonic acid.…”

Section: Chemical Modificationssupporting

confidence: 84%

“…Four intense bands at 960, 1 314, 1 401, and 1 485 cm −1 were assigned to the characteristic vibrations of the heterocyclic structure 124 . 13 C solid state NMR has also been used to characterize PBZT and PBO 127–129. Evidence of crosslinking was observed for heat‐treated MePBZT fiber at 550 °C for 30 min via a total disappearance of the methyl intensity at 26 ppm and a minor growth of a methylene resonance near 38 ppm.…”

Section: Structure and Morphologymentioning

confidence: 99%

“…Evidence of crosslinking was observed for heat‐treated MePBZT fiber at 550 °C for 30 min via a total disappearance of the methyl intensity at 26 ppm and a minor growth of a methylene resonance near 38 ppm. A mechanism of the crosslinking was accordingly suggested for this heat‐treated polymer 127…”

Section: Structure and Morphologymentioning

confidence: 99%

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Rigid‐Rod Polymers: Synthesis, Processing, Simulation, Structure, and Properties

Hu¹,

Jenkins

Min

et al. 2003

Macro Materials & Eng

Self Cite

174

105

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Synthesis, structure, and properties of rigid‐rod polymers with special emphasis on poly(p‐phenylene benzobisoxazole) (PBO) and poly(p‐phenylene benzobisthiazole) (PBZT) have been reviewed. Recent studies on chemical modifications and molecular simulations have also been given. After nearly 20 years of research and development, PBO fiber was commercialized in the late 1990s. However, due to processing difficulties, the concept of the so called molecular composites has not been successful. Development of the high compressive strength M5 and dihydroxy‐PBI fibers clearly suggest that there is potential for further developing properties of this class of materials. Opto‐electronic properties have also been reviewed.Synthesis of PBZT.magnified imageSynthesis of PBZT.

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Section: Chemical Modificationssupporting

confidence: 84%

Section: Structure and Morphologymentioning

confidence: 99%

See 1 more Smart Citation

Rigid‐Rod Polymers: Synthesis, Processing, Simulation, Structure, and Properties

Hu¹,

Jenkins

Min

et al. 2003

Macro Materials & Eng

Self Cite

174

105

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“…By incorporating a thermally reactive cross-linking moiety fluorene into PBZT (267,268), iii. Cross-linking benzobisthiazole rigid-rod copolymers via labile methyl or dimethylephenoxy pendent groups (261,(269)(270)(271)(272)(273)(274)(275), or forming copolymers of tetramethylbiphenyl PBZT/PBZT (276,277), iv. Cross-linking PBO fibers with polyphenylene sulfide pendent groups (278), and v. Cross-linking PBZT by introducing benzocyclobutene (BCB) crosslinking moieties in PBZT backbone (264,270,(279)(280)(281)(282).…”

Section: Compressive Properties As Listed Inmentioning

confidence: 99%

Rigid‐Rod Polymers

Wang¹,

Jiang²,

Adams³

2011

Encyclopedia of Polymer Science and Technology

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Pursuing high strength and high modulus polymer fibers and novel electrooptical properties have motivated much research activity in rigid‐rod polymers in the past 40 years. In this review, we examine the synthesis, structures, and properties of rigid‐rod polymers with emphasis on polybenzobisoxazoles (PBO), polybenzobisthiazoles (PBZT) and polybenzimidazoles (PBI), beginning with their solution properties, especially lyotropic liquid crystallinity. High performance fibers spun from lyotropic liquid crystalline polyphosphoric acid (PPA) solution are described. The characterization of fiber properties including mechanical, thermal, electrical, and optical properties is summarized. PBO (Zylon) and PIPD (M5) fibers were successfully commercialized in high strength applications such as body armor, ropes, cables, and recreational equipment in the last 10 years, and we discuss the possible causes of rapid degradation of some PBO fibers. The concepts of molecular composites and nanocomposites provide new applications in antiballistic materials, fire protection, athletic equipment, cables, strings, ropes, cordage, sails, multilayer circuits, and catalyst supports. Recently, rigid‐rod polymer films have drawn attention in the electrooptical fields, especially for phosphoric acid (PA)‐doped PBI membranes (Celtec MEAs) in the applications of high temperature fuel cells. Computer simulation has been employed as a powerful tool to predict the properties of the rigid‐rod polymers.

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“…Compared with the other two methods, introducing covalent cross‐linking among macromolecular chains is the most effective method and post cross‐linking during heat treatment is proposed . Some thermally reactive groups, such as aryl halogen and dithia‐ s ‐inda, were introduced into poly( p ‐phenylene terephthalamide) (PPTA) and cross‐linking could take place at 400 °C . But they found improvement in compressive strength was not significant and mechanical properties deteriorated obviously.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Heterocyclic Aramid Fiber Based on Solid‐Phase Cross‐Linking of Oligomers with Reactive End Group

Dai

Han

Yao

et al. 2018

Macro Materials & Eng

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Low compressive strength of aramid fiber is one of the major obstacles for its application in advanced composite materials. In this study, poly‐(benzimidazole‐terephthalamide) (PABI) fibers are fabricated by solid‐phase cross‐linking of corresponding oligomers end‐capped with norbornene anhydride (NA). Concentration of the spinning solution increases and apparent viscosity is reduced significantly through this method, which improves its processability. Reactivity and thermal stability of the NA group are measured by in situ Fourier transform infrared (FTIR) and thermogravimetric analysis and it shows high reactivity at 360 °C and adequate thermal stability under 400 °C. Results of solubility test and dynamic mechanical analysis indicate cross‐linking degree increases with decrease of molecular weight of the corresponding oligomer. Results of both 2D wide angle X‐ray diffraction and polarized FTIR illustrate orientation will be affected by cross‐linking and it decreases with the increase of cross‐linking degree. PABI fibers fabricated through this method can maintain outstanding mechanical properties and compressive strength is improved by 67% at most. Interestingly, interfacial shear strength of PABI fibers is improved by nearly 20% and damage between skin–core layers after debonding of fiber and resin is not observed.

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On the evidence of crosslinking in methyl pendent PBZT fiber

Cited by 16 publications

References 2 publications

Rigid‐Rod Polymers: Synthesis, Processing, Simulation, Structure, and Properties

Rigid‐Rod Polymers: Synthesis, Processing, Simulation, Structure, and Properties

Rigid‐Rod Polymers

Synthesis of Heterocyclic Aramid Fiber Based on Solid‐Phase Cross‐Linking of Oligomers with Reactive End Group

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