Copolyesters. VII. Thermal transitions of poly(butylene terephthalate‐co‐isophthalate‐co‐adipate)s

Abstract

SYNOPSISThe copolyesters of 1,4-butanediol, terephthalic acid, isophthalic acid, and adipic acid with different compositions were prepared by melt polycondensation. The intrinsic viscosity of the copolyesters was controlled to be about 0.7-1.0 dL/g. Their second-run thermal properties were determined by DSC. The composition was found to be a major factor in the determination of the thermal transitions. The effect of the composition on the glass transition temperature and melt transition temperature was interesting. The glass transition temperature was found to be dependent mainly on the content of adipic acid. As the content of adipic acid increased, the glass transition decreased. When the content of terephthalic acid was not less than 35 mol % based on the total diacid monomers, the melting temperature was dependent mainly on the content of terephthalic acid and increased with increase of the content of terephthalic acid. When the content of terephthalic acid was less than 35 mol %, the melt temperature of the copolyesters did not follow a simple rule. However, the effect of the composition on their melting enthalpy showed no simple trend. I NTRO DUCT10 NThe performance of a hot melt adhesive can be controlled by its thermal transitions including glass transition temperature ( T,) , melting temperature ( T,) , and melting enthalpy.'.' A lower Tg ameliorates flexibility and thus gives better low-temperature performance. A higher T, increases the heat resistance, but always gives a higher melt viscosity, which will influence the processability. A higher melting enthalpy improves the heat resistance and the lap shear strength, but may give poorer adhesion.The copolyesters of 1,4-butanediol and two different diacids have been considered to be used as hot melt adhesives.'-' The thermal transitions can be controlled by the chemical composition to some extent. However, it will be more flexible to incor- CCC 0021-8995/94/060999-06 porate a third diacid component to regulate the properties. Based on this observation, the copolyesters of 1,4-butanediol, terephthalic acid, isophthalic acid, and adipic acid have been used as hot melt adhesives.'-13 In our laboratory, some poly (butylene terephthalate-co-isophthalate-co-adipate ) s with a molar composition of 1,4-butanediol : terephthalic acid : isophthalic acid : adipic acid = 1 : 0.45 : 0.30 : 0.25 were prepared as hot melt adhesives.14 These copolyesters were designed to have a T, of about 110°C to fit a typical hot melt gun for the shoe sole application. In the screening of the suitable copolyesters, we also found that the Tg and the melting enthalpy were also important in determining their performance in addition to the T,.There are many' different applications for copolyester-type hot melt adhesives. To optimize the performance for different applications, it is important to understand the factors influencing the thermal transitions of the copolyesters. In this article, various poly (butylene terephthalate-co-isophthalate-co-adipate) s with a wide composition range...

Properties of thermoplastic composites based on wheat‐straw lignocellulosic fillers

“…According to their results, the selected PBAT would be about 20–25% poly(butylene terephthalate) and 75–80% poly(butylene adipate). In agreement with the results shown in Table VI and Figure 7, Chang and Tsai showed that random copolyesters of poly(butylene terephthalate‐ co ‐adipate) present a single transition for T g , T c , and T m 51…”

“…Chang and Tsai51 prepared different random copolyesters with various compositions. According to their results, the selected PBAT would be about 20–25% poly(butylene terephthalate) and 75–80% poly(butylene adipate).…”

“…In agreement with the results shown in Table VI and Figure 7, Chang and Tsai showed that random copolyesters of poly(butylene terephthalateco-adipate) present a single transition for T g , T c , and T m . 51 As shown in Table VI, the addition of increasing amounts of LCR results in a slight but significant increase in T g of PBAT. According to Avella et al, 33 this tendency may be explained by intermolecular interactions between the hydroxyl groups of the fibers and the carbonyl groups of the PBAT ester functions.…”

Antimicrobial and sustainable food packaging based on poly(butylene adipate-co-terephthalate) and electrospun chitosan nanofibers

“…As can be observed, PBAT copolymer displays a single transition for T c and T m , and these temperatures are intermediate between the data of both homopolymers. 44 The incorporation of CS-NF causes a slight increase in T m , by about 5 C at 12.0 wt% loading (Table 1), which can be attributed to the intermolecular interactions between the hydroxyl and amino groups of CS and the carbonyl groups of the ester moieties of PBAT via H-bonding.…”

Biocomposites Based on Biodegradable Thermoplastic Polyester and Lignocellulose Fibers

“…Compared to most thermoplastics, T g and T f are rather low and then processing temperature are not high, around 130 C. We can notice that this copolymer presents a single transition for T g , T c , and T m due to the repartition of the different sequences. These temperatures are intermediate between the data of both homopolymers, polybutylene adipate and polybutylene terephthalate (Chang and Tsai 1994). At room temperature, PBAT is on the rubber plateau, i.e., between T g and T f .…”