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

Abstract

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...

The flame‐retardant properties and mechanisms of poly(ethylene terephthalate)/hexakis (para‐allyloxyphenoxy) cyclotriphosphazene systems

“…The results indicated that the crystalline of PET/PACP composites was strengthened. It was caused by the phenyl group‐containing PACP was a kind of heterogeneous nucleation agent . Meanwhile, a slight decrease of the Tc and △ H C of PET/PACP appeared with the increase of PACP contents, for instance, the Tc of PET/15%PACP decreased from that of PET/5%PACP (200.2°C) to 197.0°C, △ H C from 41.95 J/g to 35.80 J/g as well.…”

High-Temperature Auto-Cross-Linking Cyclotriphosphaznene: Synthesis and Application in Flame Retardance and Antidripping Poly(ethylene terephthalate)

“…The results indicated that the crystallinity of PET/HPAIPC composites was strengthened. This was caused by the phenyl group containing HPAIPC acting as a kind of heterogeneous nucleation agent. − In addition, the T m of PET/HPAIPC composites slightly increased, in contrast to that of pure PET; the corresponding Δ H m of PET/10%HPAIPC and PET/15%HPAIPC increased by 1.46 J/g and 0.63 J/g, respectively. Therefore, one simple conclusion was summarized: the crystallinity of PET/HPAIPC composites could be promoted by the melt-blending of HPAIPC into PET matrix, which could meet application requirements.…”

Preparation of Hybrid Nanoparticle Nucleating Agents and Their Effects on the Crystallization Behavior of Poly(ethylene terephthalate)

“…For PET, the values of n were 3.1–3.9, which indicates that the nucleation of pure PET may be homogeneous with three-dimensional growth. While the values of n for the composites were 2.9–3.3, implying that the crystal growth of composites was likely linear growth (two-dimensional and three-dimensional growth) after heterogeneous nucleation [ 25 , 26 , 27 , 28 , 29 , 30 ]. The values of Z c increased with the addition of nucleating agents at the same cooling rate, suggesting a higher crystallization rate was caused compared with PET.…”