Dielectric and thermoanalytic behavior of moisture and water in aromatic polyamide paper

1993 ◽  
Vol 28 (3) ◽  
pp. 309-314 ◽  
Author(s):  
S. Yasufuku ◽  
M. Todoki
Keyword(s):  
Aromatic Polyamide

Ultrastrong, Free-Standing and Large Nanofilms of Pyrenearamid

2019 ◽  
Author(s):  
Amalia Rapakousiou ◽  
Alejandro López-moreno ◽  
Belén Nieto-Ortega ◽  
M. Mar Bernal ◽  
Miguel A. Monclús ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Block ◽  
Aromatic Polyamide ◽  
Free Standing ◽  
Spatial Confinement ◽  
Polymeric Structure ◽  
Reduced Modulus ◽  
Organizational Arrangement ◽  
Polycyclic Aromatic ◽  
Nanoscale Building Block

We introduce poly(1,6-pyrene terephthalamide) polymer (PPyrTA) as an aromatic polyamide analogue of poly(p-phenylene terephthalamide) (PPTA), also known as Kevlar®. This work shows that the incorporation of polycyclic aromatic pyrene moieties improves drastically the mechanical properties of the polymeric structure, increasing elastic nanoindentation-determined modulus and hardness by factors of 1.9 and 4.3, respectively. Liquid deprotonated dispersions of PPyrTA nanofibers were used as nanoscale building block for producing large-surface, free-standing polymer macroscopic nanofilms. This 2D assembly leads to further significant improvements in reduced modulus and hardness (more than twice) compared to the starting polymer macroscale fibres, due to a better re-organizational arrangement of the PPyrTA nanofibers in the nanofilms, formed under 2D spatial confinement.

Design of recyclable, fast-responsive and high temperature shape memory semi-aromatic polyamide

Polymer ◽  
2021 ◽  
Vol 216 ◽  
pp. 123427
Author(s):  
Guang-ming Yan ◽  
Han Wang ◽  
Dong-sheng Li ◽  
Hao-ran Lu ◽  
Sui-lin Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Aromatic Polyamide

Engineering all‐aromatic polyamide surface from hydrophilic to superhydrophobic and the accelerated strategy

2021 ◽  
pp. 51316
Author(s):  
Jing Lv ◽  
Longhai Guo ◽  
Chunjie Xie ◽  
Weitong Xu ◽  
Jun Ye ◽  
...  
Keyword(s):  
Aromatic Polyamide

ChemInform Abstract: Syntheses and X-Ray Structures for Model Compounds of a Pyrimidinediyl- Based Rigid-Rod Aromatic Polyamide.

ChemInform ◽  
2010 ◽  
Vol 23 (17) ◽  
pp. no-no
Author(s):  
A. G. OERTLI ◽  
W. R. MEYER ◽  
U. W. SUTER ◽  
F. B. JOHO ◽  
V. GRAMLICH ◽  
...  
Keyword(s):  
Aromatic Polyamide ◽  
Model Compounds ◽  
X Ray ◽  
Rigid Rod

Synthesis, characterisation and properties of aramid copolymers prepared from AB and AB2 monomers

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Orietta Monticelli ◽  
Stefano Fiori ◽  
Alberto Mariani ◽  
Saverio Russo ◽  
Hartmut Komber
Keyword(s):  
Liquid Crystalline ◽  
Reaction Medium ◽  
Aromatic Polyamide ◽  
Degree Of Crystallinity ◽  
Feed Ratio ◽  
Structure Evolution ◽  
Monomer Composition ◽  
Degradation Temperature ◽  
Monomer Feed ◽  
Monomer Feed Ratio

Abstract Aromatic polyamide (aramid) copolymers having a highly branched architecture were prepared by direct polycondensation of an AB2 monomer (5-(4-aminobenzoylamino) isophthalic acid) with an AB monomer (N-(4-aminophenyl)terephthalamic acid). Two synthetic routes have been followed for copolymer preparation, differing from each other in the overall monomer content and the type of salts added to the reaction medium (LiCl or LiCl + CaCl2). Otherwise, both methods used the same conditions and the same condensing agent (triphenyl phosphite). The feed ratio of the monomers affected the copolymer solubility in aprotic polar solvents such as N,N-dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide. Only high AB2/AB monomer ratios allowed obtaining completely soluble polymers in the above media. Also copolymer intrinsic viscosity was influenced by that ratio as well as by the polymerisation routes. IR measurements gave an indication of polymer structure evolution as a function of the monomer feed ratio, while 1H NMR experiments verified the actual monomer composition in the synthesized polymers. The monomer feed ratio turned out to influence polymer properties, such as degree of crystallinity, thermal degradation temperature and liquid crystalline behaviour. Some of the characterisation techniques we used (1H and 31P NMR, IR, SEM-EDS) revealed the presence of phosphorus derivatives in the copolymers, despite extensive sample purification. This presence is coming from derivatives of the condensing agent, and is directly related to the content of AB2-type structures present in the copolymers.

The methylenic sequence conformation in a series of isoelectronic molecules

1988 ◽  
Vol 66 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Suzanne Deguire ◽  
François Brisse
Keyword(s):  
Solid State Nmr ◽  
Weighted Least Squares ◽  
Direct Methods ◽  
Aromatic Polyamide ◽  
Amide Group ◽  
Trans Conformation ◽  
A Value ◽  
Isoelectronic Series ◽  
Isoelectronic Molecules ◽  
Related Compounds

The crystal structures of 1,4-dibenzoylbutane, 2DBC, and ethyleneglycol dithiobenzoate, 2DBS, have been solved by direct methods in order to follow the evolution of the geometry and the conformation of the Y—CH2—CH2—Y sequence in the isoelectronic series of C6H5—CO—Y—CH2—CH2—Y—CO—C6H5 where Y = CH2, NH, O, and S. 2DBC is monoclinic, a = 7.750(4), b = 21.287(6), c = 8.905(2) Å, β = 100.55(3)°, Z = 4. 2DBS is also monoclinic, with a = 5.702(3), b = 16.171(15), c = 8.001(4) Å, β = 98.79(4)°, and Z = 2. Both compounds belong to the P21/n space group. The weighted least-squares refinements converged to Rw = 0.049 (2DBC) and 0.043 (2DBS). The conformation of the methylenic sequence is all-trans (2DBC) and g+tg− for 2DBS (t = trans, g = gauche). The ir spectra have absorptions at 1467, 1308, and 931 cm−1 (2DBC) and at 1408, 1239, and 727 cm−1 (2DBS), respectively, characteristic of the trans conformation of the Y—CH2—CH2—Y sequence. The 13C CP/MAS solid-state nmr spectra of these and other related compounds have been recorded. It is, in turn, possible to propose that the τ torsion angle between the amide group and the methylenic sequence, has a value of 85° in the aromatic polyamide, Nylon 2T.

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