Copolyamides from adipic and truxillic acids: Synthesis and characterization by direct pyrolysis in the mass spectrometer (original) (raw)
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Journal of Polymer Science: Polymer Chemistry Edition, 1975
The thermal degradation mechanism of four isomeric t d c and truxinic polyamides were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method by detecting the thermal and electron impactrinduced fragments. The results obtained have shown that the thermal degradation products are sensibly different for the head-to-head (hh) and headr to-tail (ht) polymers and that the predominant pyrolytic process is the cyclobutane ring cleavage. In the hh isomers, both symmetrical and asymmetrical cyclobutane ring cleakage was detected, while in the ht isomers only symmetrical cleavage occurs; this explains the noticeable difference found in the thermal stability of the two polymer types. Polyamides derived from the condensation of truxillic and truxinic acid (dimers of cinna'mic acid) with aliphatic diamines are highly photodegradable materials, and their intered in this respect has been recently pointed out, in view of possible practical applications.'S2 We have now investigated the thermal stability of four isomeric polyamides of this family (I-IV) by direct pyrolysis in the mass spectrometer n U cas ca5xc0-N coN co cA.# m C&FJ I
Structural Characterization of Copolyamides Synthesized via the Facile Blending of Polyamides
Macromolecules, 2004
Ny6-Ny6,10 and Ny6-Ny4,6 copolyamides prepared by a facile melt mixing at 290-310°C of carboxyl terminated Nylon6 (Ny6-COOH) with Ny6,10 or Ny4,6, were characterized by MALDI, 13 C NMR, and DSC analysis. The results, from one side show how facile is the high yield synthesis of random copolyamides via the melt mixing of the corresponding polyamides. What makes the synthesis so facile is the use of a carboxyl terminated polyamide (Ny6-COOH) to attack the other polyamide (Ny4,6 or Ny6,10), as described herewith. The DSC data acquired provide a clear picture of the process. The second relevant point is about the sequence analysis of the copolyamides, made using their 13 C NMR spectra. The sequence has been derived directly from chain statistics principles, avoiding the use of inadequate procedures. To our knowledge, this is the first time as far as condensation copolymers are concerned. Interesting, the sequence analysis of our copolyamides has been also performed independently, by extracting pertinent information from their MALDI spectra. The results have been found in excellent agreement with those from 13 C NMR data.
Polymers, 2018
This work investigated the synthesis of a novel low melting temperature polyamide 6 (PA6) copolyamide (PA6-BABT/SA) with different aliphatic/aromatic units weight content using a melt poly-condensation process. The bio-based aromatic N1,N4-bis(4-aminobutyl) terephthalamide diamine (BABT) and long-chain aromatic polyamide salt (BABT/SA, salt of BABT, and sebacic acid), components used for the synthesis of copolyamides, were obtained from bio-based monomers. For the first time, the pertinent BABT/SA aromatic polyamide salt was isolated as a white solid and completely characterized. By varying the weight ratio of BABT/SA salt, a series of copolyamides with different molecular weights and physical properties were prepared. The aromatic BABT/SA salt disrupted crystallization of the final copolyamides and lowered the onset of melting. The Fourier transform infrared spectroscopy and X-ray diffraction results indicated a steady decrease in the degrees of crystallinity with increasing BABT/S...
The DSC Study of PA 6, Polyamides and Copolyamides
Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM, 2000
The DSC method was used to obtain more information on changes of thermal properties connected with different comonomers bound in the (co)polymer chains. The copolyamides propered were block ones which were less crystalline and compatible with poly-ε-caprolactam. The results have confirmed the crystalline nature of polyamides and copolyamides.
Journal of Polymer Science Part A: Polymer Chemistry, 1987
The thermal decomposition processes of two polyamides, derived from succinic acid and two aromatic diamines, were studied by direct pyrolysis mass spectrometry. Fast atom bombardment (FAB) mass spectrometry has been also used in order to provide additional information for the elucidation of the thermal degradation mechanism of the polymers investigated. FAB mass spectra, obtained by introducing in the FAB ion source the solid residues from polymer pyrolysis performed in thermogravimetric experiments, allowed the detection of diagnostic compounds up to about 1600 amu. Our results indicate that the thermal stability of the N-methyl-substituted polyamide is higher than that of the unsubstituted polyamide. The difference in the thermal degradation mechanism accounts for the difference in the thermal stability of the two polyamides. In fact, the unsubstituted polyamide decomposes via an intramolecular exchange and a concomitant N-H hydrogen transfer process with formation of compounds with amine and/or succinimide end groups. Instead, the N-methyl-substituted polyamide decomposes via an a C-H hydrogen transfer process from the methyl group to the nitrogen atom with formation of compounds with amine and/or 2,5-piperidinedione end groups.
Thermal degradation of new copolymers from pyromellitic anhydride
Polymer, 1989
A series of new copolyimides has been synthesized from pyromellitic anhydride. Copoly(imide esters) and copoly(imide amides) were synthesized from bis(N-methylcarboxychloride)pyromellitimide with diols and amines, respectively. One copoly(imide amine) was obtained from bis(N-allyl)pyromellitimide and piperazine via the Michael reaction. The thermal degradation of the copolymides obtained was studied by direct pyrolysis mass spectrometry. Our results show that a selective//-CH hydrogen transfer reaction occurs in copoly(imide esters) containing 1,3-propyl and 1,6-hexane diols, while an intramolecular ester exchange process takes place in copoly(imide ester) with a neopentylglycol moiety. Copoly(imide amide) containing 1,6-hexane diamine decomposes by an N-H hydrogen transfer process, although extensive crosslinking is observed, while that containing piperazine decomposes by an ct-CH hydrogen transfer. In contrast, copoly(imide amine) undergoes a very selective depolymerization process, yielding bis(Nallyl)pyromellitimide and piperazine.
Journal of Polymer Research, 2019
Six aromatic copolyamides contanining phenyl groups were synthesized and characterized. The concentrations of the paralinked phenyl groups and meta-linked phenyl groups were varied systematically on the copolymers general structure to obtain a set of random copolyamides. Effect of copolymerization on glass transition temperature (T g), tensile modulus (E), Tensile strength (σ) were measured. Changes in density were determined to estimate the effect on Fractional Free Volume (FFV). Results indicate that the substitution of para-linked phenyl group by meta-linked phenyl group causes an increase in tensile modulus E and tensile strength a decrease in T g. The observed results are attributed to the asymmetric position of the linkages in the TERE and ISO isomers, because symmetric linkages, such as TERE, induces a higher packing of the polyamide chains while the asymmetry of ISO isomer inhibits packing causing an expansion in the FFV.
Primary thermal decomposition processes in aliphatic polyamides
Polymer Degradation and Stability, 1989
The thermal decomposition mechanisms of several polyesters, derived from aliphatic diols and bicarboxylic acids, and polylactones were studied by direct pyrolysis-mass spectrometry, using both positive chemical ionization and negative chemical ionization. In fact, it was found that the thermally formed compounds are not stable under electron impact conditions. Instead, the results obtained by positive and negative chemical ionization indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation processes, causing the formation of cyclic oligomers, which are particularly stable under chemical ionization conditions. The only exception is given by poly(0-propiolactone); in this case the thermal decomposition mechanism involves @-hydrogen transfer reactions.
Polymers
N1, N6-bis (4-aminobutyl) adipamide (BABA) diamine and sebacic acid (SA), also called BABA/SA polyamide salt, were used in a typical melt polymerization processes of polyamide 6 (PA6) to form a series of PA6-BABA/SA copolyamides. The effects of BABA/SA on the isothermal crystallization kinetics of PA6-BABA/SA were studied for the first time. An isothermal crystallization analysis demonstrates that the PA6-BABA/SA matrix provided a higher crystallization rate and shorter half-crystallization time than virgin PA6 did. The degree of crystallization of the PA6-BABA/SA30 matrix was also the lowest among all of the samples considered herein. This result is attributed to the high nucleation efficacy of a small amount of BABA/SA in the crystallization of PA6. Values of the Avrami exponent (n) from 1.84 to 3.91 were observed for all of the polyamide samples, suggesting that the crystallization was involved via a two- to three-dimensional growth mechanism. These findings deepen our understand...
Polymer Degradation and Stability, 2007
Pyrolysis products with mass of up to 850 Da were detected by direct pyrolysis mass spectrometric (DPMS) analysis of a series of copoly(arylene ether sulfone)s (PESePPO) synthesized by nucleophilic condensation of either 4,4 0 -dichlorodiphenylsulfone (CDPS) or 4,4 0 -bis-(4-chlorophenyl sulfonyl) biphenyl (long chain dichloride, LCDC) with different molar ratios of hydroquinone (HQ) or dihydroxydiphenylsulfone (HDPS). Pyrolysis products retaining the repeating units of the initial copolymers were formed at temperatures ranging from 420 C to 470 C (near the initial decomposition temperature). At temperatures higher than 450 C were observed products containing biphenyl units, formed by the elimination process of SO 2 from diphenyl sulfone bridges. Products having biphenyl and dibenzofuran moieties were detected in the mass spectra recorded at temperatures above 550 C. These units were formed by loss of hydrogen atom from diphenyl ether bridges. Although the EI (18 eV) mass spectra of the pyrolysis products of the samples investigated were very similar, it was found that the relative intensity of some ions reflects the molar composition of the copolymers analysed. Cyclic and linear oligomers with very low molecular mass, present in the crude copolymers, were also detected by DPMS. Thermogravimetric analysis also showed their excellent thermal stability below 400 C. It indicates that the copolymers yield a char residue of 40e45% at 800 C, which increases with the PPO mole fraction in the samples.