Isothermal and nonisothermal crystallization kinetics of novel odd–odd polyamide 9 11

Kang

J of Applied Polymer Sci

et al. 2018

The non-isothermal crystallization behaviors of PA56, PA66, and PA56/PA66 blends were studied by differential scanning calorimetry. The Jeziorny and Mo's methods were used to analyze their non-isothermal crystallization kinetics. The results indicated that Mo's method was better to describe the experimental data in this work. The crystallization rate of PA56 was much slower than that of PA66. The crystallization rate of PA56/PA66 blend was speeded up significantly with the increasing PA66 content when the PA66 content was less than 30 wt %. Further increase in the PA66 content only leads to relatively less increase of the crystallization rate in the PA56/PA66 blends. Activation energies have been determined with Friedman method. The activation energy of PA56/PA66 blends is decreased and lower than that of PA56. PA66 may play a role of nucleating agent toward PA56 to make it crystallize more easily in PA56/PA66 blends.

Section: Resultsmentioning

confidence: 99%

Crystallization of polyamide 56/polyamide 66 blends: Non‐isothermal crystallization kinetics

Kang

J of Applied Polymer Sci

et al. 2018

J Polym Sci B Polym Phys

“…However, there are few reports in the literature about piezoelectricity and ferroelectricity in odd‐odd polyamides. Although some researchers have predicted the potential ferroelectricity in odd‐odd polyamides, whether or not odd‐odd polyamides are ferroelectric and piezoelectric remains unknown due to the different ability of forming hydrogen bonds and thus different crystal structures compared to odd polyamides. If they are, it is still unknown which regions will be responsible for the ferroelectricity and what is the mechanism.…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric behavior and polarization mechanism in odd‐odd polyamide 11,11

Liu

Cui

et al. 2014

Ferroelectric and piezoelectric behavior in odd‐odd polyamide 11,11 are successfully detected for the first time. The maximum coercive field (Ec) of 90 MV/m, and a remnant polarization (Pr) of 40 mC/m2 are obtained at room temperature. A piezoelectric strain coefficient (d33) value as high as −3.9 pC/N has been found in stretched polyamide 11,11 film. The structural change of samples before and after poling is investigated by wide‐angle X‐ray diffraction patterns, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The results indicate that the nature of the ferroelectricity originates from amide group dipoles in the γ‐form crystal regions. Hysteresis behavior appears to result from the crystallites reversal mechanism. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1094–1099

“…The crystallization process is usually treated as a composition of two stages: the primary crystallization stage and the secondary crystallization stage . A slow increase of relative crystallinity was observed, and this was attributed to the presence of secondary crystallization .…”

Section: Resultsmentioning

confidence: 99%

The crystallization behaviors of copolymeric flame‐retardant poly(ethylene terephthalate) with organophosphorus

Liang

et al. 2013

Polymer Composites

The crystallization behaviors of copolymeric flameretardant poly(ethylene terephthalate) (PET) with organophosphorus were studied using differential scanning calorimetry (DSC). The results indicated that the degree of tacticity of molecular chain of PET declined due to the presence of organophosphorus which had an important impact on isothermal and nonisothermal crystallization behaviors apparently. In the process of isothermal crystallization, the more organophosphorus the samples contained, the faster the samples crystallized and it resulted from the special structure of PET copolymer with organophosphorus in it. The equilibrium melting temperature of PET decreased from 284.87 to 260.728C as the content of organophosphorus increased from 0 to 0.96 wt%, whereas in the process of nonisothermal crystallization, the Avrami exponent n decreased with the growth of the content of organophosphorus, and the addition of organophosphorus made the nucleation mechanism and the growing geometry less complicated. POLYM. COMPOS., 34:867-876, 2013. ª 2013 Society of Plastics Engineers INTRODUTIONAs a well-established engineering polymer, poly(ethylene terephthalate) (PET) is widely used in the manufacture of fiber, film, tape, moldings, pressurized liquid containers [1], and many other industry processes for its high melting point, good thermal and electrical insulations, excellent mechanical properties, it is and now it has already become a subject of many researches [2]. But PET is a slow crystallizing polymer, and the flammability of PET is a shortcoming in some applications like other organic materials.In order to overcome the flammability of PET, the researchers have already been focusing on the study of flame-retardant PET. For now, there are mainly two methods to improve the flame retardancy of polymers, copolymerization and compound. For example, Wang [3] with his colleagues put [(6-oxide-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)-methyl]-butanedioic acid and other phosphorus-containing flame retardants into PET in order to make into PET copolymers to perfect the flame retardancy of PET and the results showed that the limit oxygen index (LOI) values of all phosphorus-containing polysters were higher than 27%. On the other hand, Tugba [4] has ever put the nanoclay and carbon nanotubes as additives into the organophosphorus flame-retardant poly(methyl methacrylate) to improve the flame retardancy of polymer. But compared to the method of compound, copolymerization can make the flame-retardant properties durable and hardly affect other properties of polymers. The improvement of the flame retardancy of PET via the introduction of an additive flame retardant especially fluoride, chlorine, nitrogen and phosphorous has been reported in the literature [5]. The halogencontaining flame retardants play an important role because of their high efficiency while added into polymeric materials. These additives are generally satisfactory with respect to their flame-resistant characteristics, but their toxicity and corrosion will cause en...