Behavior of aromatic polyamides in dilute sulfuric acid solutions

Koretskaya, A. I.; Babushkina, M. P.; Kudryavtsev, G. I.; Mileshkina, L. V.

doi:10.1007/bf00548038

Cited by 2 publications

(3 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Relative to PPTA, the intrinsic viscosity strongly decreases with the incorporation of methylene units. The decrease in the viscosity is in accordance with the reduction in chain stiffness …”

Section: Resultssupporting

confidence: 58%

“…The decrease in the viscosity is in accordance with the reduction in chain stiffness. 25 The solubility of the aromatic−aliphatic polyamides has been further investigated in 100% H 2 SO 4 and in a NMP/CaCl 2 (10% w/w) solution. All aromatic−aliphatic polyamides show solubility in H 2 SO 4 up to ∼35% (w/w) and in NMP/CaCl 2 up to ∼20% (w/w).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Conformational and Structural Changes with Increasing Methylene Segment Length in Aromatic–Aliphatic Polyamides

et al. 2016

View full text Add to dashboard Cite

The synthesis and structural characterization of various aromatic–aliphatic polyamides are reported in this study. The polymers are obtained by solution polymerization of p-phenylenediamine with various aliphatic diacid chlorides. The resulting polyamides are labeled PA P-X, where X varies between 5 and 10 and corresponds to the number of carbon atoms of the dicarboxylic acid monomers used in the synthesis. The polyamides are obtained with M n values of 10 kg/mol or higher, as determined by solution NMR spectroscopy and gel permeation chromatography (GPC). The polymers PA P-5 to PA P-8 degrade prior to melting, whereas only PA P-10 shows melting on heating. The structural changes in the polymers, with increasing methylene segments, are investigated by X-ray diffraction and molecular modeling. Conformational changes as a function of temperature have been studied by solid-state NMR spectroscopy. These studies have been illustrative in following the phase transformations in the aromatic–aliphatic polymers. For the crystal packing of the polymer based on the odd acid (PA P-5) a sheetlike structure, similar to that of the aromatic polyamide PPTA, is observed. Despite the presence of the odd spacer, PA P-5 exhibits a hydrogen bonding length very similar to that of PPTA, whereas the intersheet distance increases and the interchain distance decreases. As a result, the crystal structure of PA P-5 is distinctively different from that of the aliphatic polyamides having the same odd diacid, e.g. PA 65. In contrast, the crystal packing of PA P-6 with even diacid is similar to that of the α form of PA 46. The change of the chemical shift of the carbonyl groups with increasing number of methylene units suggests a weakening in the hydrogen bonding with respect to PPTA. For PA P-10 this weakening ultimately translates to melting of the polymer prior to degradation.

show abstract

Section: Resultssupporting

confidence: 58%

Section: ■ Results and Discussionmentioning

confidence: 99%

Conformational and Structural Changes with Increasing Methylene Segment Length in Aromatic–Aliphatic Polyamides

et al. 2016

View full text Add to dashboard Cite

show abstract

“…For PPTA, it was found that [11] = 1.3rllo ~ [3]. Using this expression, we can determine [11] and M w with one measurement of Tlrel.…”

mentioning

confidence: 97%

Effect of the molecular weight of poly-para-aramids and structural changes in heat treatment on the mechanical indexes of the fibres

Kiya-Oglu¹,

Volokhina²,

Banduryan³

1999

Fibre Chem

View full text Add to dashboard Cite

The mechanical indexes of fibres based on tuv types of poly-para-aramids were investigated as a function ofC is the concentration of polymer in 96% sulfuric acid, equal to 0.5 g/dl. For PPTA, it was found that [11] = 1.3rllo ~ [3]. Using this expression, we can determine [11] and M w with one measurement of Tlrel. According to the equations reported above, the curve of Mw(qlog) is almost linear.Fibres with a linear density of 30 and 58.8 tex consisting of 100 and 300 filaments, respectively, were fabricated by spinning 20 wt. % liquid-crystalline (LC) sulfuric acid solutions of copolyamides through an air gap using spinnerets with an 0.08 mm opening diameter into an aqueous spinning bath with a temperature of 10~ at a take-up rate of 100 m/rain according to [4] with washing and drying of the 30 tex fibres on perforated bobbins at 20~ and continuous washing and Terlon Limited Partnership; All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi.

show abstract

Behavior of aromatic polyamides in dilute sulfuric acid solutions

Cited by 2 publications

References 4 publications

Conformational and Structural Changes with Increasing Methylene Segment Length in Aromatic–Aliphatic Polyamides

Conformational and Structural Changes with Increasing Methylene Segment Length in Aromatic–Aliphatic Polyamides

Effect of the molecular weight of poly-para-aramids and structural changes in heat treatment on the mechanical indexes of the fibres

Contact Info

Product

Resources

About