Modeling the effect of crosslinking in methyl-pendant poly(p-phenylene benzobisthiazole)

Jenkins, Shawn; Jacob, Karl I.; Kumar, Satish

doi:10.1002/(sici)1099-0488(199812)36:17<3057::aid-polb6>3.0.co;2-k

Cited by 13 publications

(12 citation statements)

References 19 publications

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“…This cracking phenomenon in MePBZT has been investigated using atomistic simulation techniques. Simulations suggest an internal stress is generated on crosslinking 220. Experimental observations, consistent with the simulated results, have also been reported 221.…”

Section: Chemical Modificationssupporting

confidence: 81%

“…Swelling studies were used as a means to detect the presence of crosslinking in these materials, with electron radiation dosages as high as 30 Mrad being used 237. Electron radiation has also been used in an attempt to crosslink methyl and dimethyl PBZT and observe the presence of crosslinks (i.e., via solid‐state 13 C NMR) 238. Crosslinking was not detected upon exposure to as high as 1 Grad radiation dosage.…”

Section: Chemical Modificationsmentioning

confidence: 99%

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

Hu¹,

Jenkins

Min

et al. 2003

Macro Materials & Eng

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173

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: 81%

Section: Chemical Modificationsmentioning

confidence: 99%

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

Hu¹,

Jenkins

Min

et al. 2003

Macro Materials & Eng

Self Cite

173

105

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“…18,19 Other major problems are the "peeling" effect and the low resistance to compression. [20][21][22][23][24] These problems arise from the strong anisotropy of fibers, which exhibit high modulus along the fiber axis and a low one in the perpendicular direction. The reason can be attributed to weak chain-to-chain transversal interactions: the insertion of dipolar groups along the chain, as for example the polyamide, may reduce such an effect.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Molecular Structure of Cross-Linkable Rigid-Rod Liquid Crystalline Polyesters Containing Side Allyl Groups.

et al. 2000

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The synthesis and characterization of a new class of rigid-rod liquid crystalline polyesters [R( n )] bearing side groups is reported. R( n ) were prepared by interfacial polycondensation of n-alkoxyterephthaloyl chloride and 3,3‘-diallyl-4,4‘-dihydoxybiphenol exploiting the good solubility in chloroform promoted by the side flexible groups. R( n ) show a mesophase at room temperature, and crystallize in some cases (n = 4−7) upon annealing. The crystalline phase has been resolved and refined (space group P21, 2 chains per unit cell). The molecular packing is characterized by a layered organization of chains, with pendant groups placed between layers. At high temperature, R( n ) show the nematic phase. Polymers can be processed to form fibers, with the exception of R(1) which cross-links very quickly in the molten state. Heating at temperature over 200 °C or annealing in the solid-state induces cross-linking of allyl groups. In the latter case, the macro-orientation of fibrous samples can be quenched. R(5) and R(10) each show a constant tensile modulus of 1 and 0.5 GPa, respectively, in the range of temperature from about 150 to 300 °C.

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“…However, the stresses generated on intermolecular cross-linking are still a likely source for the drop in fiber tensile strength in the free-annealed fibers. 25 It can be argued that the tensile strength reduction in the free-annealed samples may be a result of degradation. However the degradation in the free-and tension-annealed samples should be comparable.…”

Section: Resultsmentioning

confidence: 99%

A Tetramethylbiphenyl Poly(benzobisthiazole): Synthesis, Chracterization, Fiber Spinning, and Properties

Polk

Kumar

2000

Macromolecules

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Poly(benzobisthiazole)s containing an o-tetramethyl substituted biphenyl moiety were synthesized based on 2,5-diamino-1,4-benzenedithiol dihydrochloride and 2,2′,6,6′-tetramethylbiphenyl-4,4′-dicarbonyl chloride. Homopolymerization of the two monomers and copolycondensation of the two monomers with terephthaloyl chloride were carried out in poly(phosphoric acid) (PPA). The interfacial polymerization technique was used to enhance the formation of a homogeneous liquid crystalline polymer solution suitable for fiber spinning. Copolymers of tetramethylbiphenyl PBZT/PBZT (25/75) were successfully spun into fibers from liquid crystalline solutions in PPA. Fibers were thermally cross-linked between 500 and 550 °C. The thermal cross-linking reaction was studied by thermogravimeteric analysis and by 13 C solid-state NMR spectroscopy. Fiber morphology and properties are also reported and discussed.

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Modeling the effect of crosslinking in methyl-pendant poly(p-phenylene benzobisthiazole)

Cited by 13 publications

References 19 publications

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

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

Synthesis, Characterization, and Molecular Structure of Cross-Linkable Rigid-Rod Liquid Crystalline Polyesters Containing Side Allyl Groups.

A Tetramethylbiphenyl Poly(benzobisthiazole): Synthesis, Chracterization, Fiber Spinning, and Properties

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