Characterization of poly(p-phenylene-cis-benzobisoxazole) in methanesulfonic acid

Roitman, Daniel B.; Wessling, Ritchie A.; McAlister, Jan

doi:10.1021/ma00071a030

Cited by 60 publications

(37 citation statements)

References 15 publications

(28 reference statements)

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“…The rotational freedom of PVP monomer units around -C-C-single bonds can provide a less-flexible chain [10,11,15]. We have tried to adjust our curve, by the second-order least-squares regression [13]. This adjustment is presented in Fig.…”

Section: Intrinsic Viscositymentioning

confidence: 99%

“…In this article we also propose an equation, based on the second order least-squares regression, relating the intrinsic viscosity to the molecular mass of polymer as a special case to determine, in the other hand, the approximate values of MarkHouwink-Sakurada exponents [13]. Still, the motivation of this study came from the observation of difference between the molecular weight M w and "viscosity-average" molecular weight M η  , especially at higher masses [14].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques

2007

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Abstract:The behavior of poly(vinyl pyrrolidone) (PVP) in methanol was examined using several independent methods. The hydrodynamic radius (R h ) of individual samples, over a range of molecular weights (10,000-360,000), was determined using dynamic light scattering (DLS) measurements. Dynamic Light Scattering (DLS) techniques directly probe such dynamics by monitoring and analyzing the pattern of fluctuations of the light scattered from polymer molecules. Some viscosity measurements were also performed to complete the DLS measurements and to provide more information on the particle structure. The results obtained with PVP-methanol system showed that plotting the variation of intrinsic viscosity versus the logarithm of the molecular mass of this polymer, we observe one crossover point. This crossover point appears when we reach the Θ-solvent behavior and delimit two molecular mass regions. The second order least-squares regression was used as an approach and was in excellent agreement with viscometric experimental results.

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Section: Intrinsic Viscositymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques

2007

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“…It is formed from a complex ring but the direction of the molecule is close to a straight line 1,2 . Therefore, the choice of a good solvent for the molecule is much limited for spinning and polyphosphoric acid is a reasonable choice for selecting a good solvent 3 .…”

Section: Introductionmentioning

confidence: 99%

A Novel Random Preferential Orientation of the Crystal A‐axis Along the Radial Direction Confirmed on the Poly‐<i>p</i>‐phenylenebenzobisoxazole (PBO) Fiber Made with a Water

2015

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“…To improve this mechanical properties much higher, we have been looking into the structural formation of fiber during coagulation and found that a non-aqueous coagulant gives a different fiber structure 1 . The fiber is expected to have a higher molecular orientation with less structural inhomogeneity along the fiber axis, which has been revealed by small and wide-angle X-ray diffraction (SAXS and WAXS) techniques and high-resolution transmission electron microscope (HREM) observation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Figure 1 shows the relationship between fiber modulus and the crystallite orientation of the (200) diffraction of the PBO crystal estimated by X ray, in which the three fibers show high molecular orientation to the fiber axis than other conventional fibers 19 .…”

Section: Introductionmentioning

confidence: 99%

The Effect of Non-Aqueous Coagulation in the Structure of Poly-<i>p</i>-phenylenebenzobisoxazole (PBO) Fibers

Kitagawa¹,

Sugihara²,

Tsutsumi³

2015

Sen-i Gakkaishi

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IntroductionA recent success of the development of poly-pphenylenebenzobisoxazole (PBO) fiber gives highstrength and high-modulus materials, which might be useful in such an area like an aerospace industry to replace heavy metals. To improve this mechanical properties much higher, we have been looking into the structural formation of fiber during coagulation and found that a non-aqueous coagulant gives a different fiber structure 1 . The fiber is expected to have a higher molecular orientation with less structural inhomogeneity along the fiber axis, which has been revealed by small and wide-angle X-ray diffraction (SAXS and WAXS) techniques and high-resolution transmission electron microscope (HREM) observation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Figure 1 shows the relationship between fiber modulus and the crystallite orientation of the (200) diffraction of the PBO crystal estimated by X ray, in which the three fibers show high molecular orientation to the fiber axis than other conventional fibers 19 . A newly-developed ultra-high modulus PBO fiber (code name : HM+) made through such a non-aqueous coagulation process followed by a heat-treatment under tension shows 360 GPa in modulus, which value is definitely greater than that of the commercial high modulus type PBO HM fiber (280 GPa) 1 . It is noted that the HM fiber is made with aqueous coagulation before heat treatment with tension. High mechanical properties inevitably will be a reflection of such structural features of the PBO HM+ fibers. Also the fiber shows much structural difference in skin and core parts if it is compared with the commercial PBO fibers 17 .There arose another interest to see a relationship between surface and internal structures of the PBO fibers. Because the HM+ fiber has a different internal fiber structure from the viewpoint of molecular orientation especially when one look into the difference of molecular orientation of the fiber axis along the radial direction of the fiber 17 , the surface structure is inevitably more affected and shows relatively higher molecular orientation Abstract: This article concerns surface roughness of PBO fibers. Atomic force microscopy is applied to measuring the surface roughness of the PBO AS, HM and HM+ fibers. Also linear thermal expansion was measured. The reason that the surface roughness is decreased as fiber modulus increases is discussed from the viewpoint of microscopic fiber surface structure. There is a discussion in that the smoothness of fiber surface has relation with fiber modulus, molecular orientation and crystallinity of the fibers. The coefficient of thermal expansion is also measured. The PBO HM+ fiber shows a lower value (−8.7 × 10 −6 K −1 ) of coefficient of thermal expansion than that of the PBO HM.

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Characterization of poly(p-phenylene-cis-benzobisoxazole) in methanesulfonic acid

Cited by 60 publications

References 15 publications

Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques

Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques

A Novel Random Preferential Orientation of the Crystal A‐axis Along the Radial Direction Confirmed on the Poly‐<i>p</i>‐phenylenebenzobisoxazole (PBO) Fiber Made with a Water

The Effect of Non-Aqueous Coagulation in the Structure of Poly-<i>p</i>-phenylenebenzobisoxazole (PBO) Fibers

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