Synthesis and Nonisothermal Crystallization Kinetics of Poly(Butylene Terephthalate-co-Tetramethylene Ether Glycol) Copolyesters

Hytrel-like Copolymers Based on Furan Polyester: The Effect of Poly(Butylene Furanoate) Segment on Microstructure and Mechanical/Elastic Performance

This paper aims to compare the performance of two Hytrel-like segmented copolymers: “classic” PBT-b-PTMG and fully bio-based PBF-b-PTMG, containing poly(butylene furanoate) as the rigid segment. The idea behind this research is to assess whether the sustainable copolymers can successfully replace those “classic” once at the thermoplastic elastomers’ market. Two series of copolymers were synthesized under the same process parameters, had the same compositions, but differed in aromatic ring structure in terephthalate/furanoate unit. Furthermore, the materials were processed by injection moulding as typical Hytrel products. Then, the samples were subjected to extensive characterisation including NMR, GPC, FTIR, DSC, WAXS, DMTA, TGA techniques and mechanical tests with particular interest in the microstructure formed during processing and its effect on the copolymers’ mechanical and elastic behaviour. The detailed analysis proved that PBF-b-PTMG and PBT-b-PTMG copolymers represent two kinds of materials with similar chemical structure, some features of thermoplastic elastomers, but evident differences in their physical properties.

A Rapid Thermal Absorption Rate and High Latent Heat Enthalpy Phase Change Fiber Derived from Bio-Based Low Melting Point Copolyesters

A series of poly(butylene adipate-co-hexamethylene adipate) (PBHA) copolymers with different content of 1,4-cyclohexanedimethanol (CHDM) was synthesized via one-step melt polymerization. The PBHA copolymer with 5 mol% CHDM (PBHA-C5) exhibited a low melting point (T_m) and high enthalpy of fusion (∆H_m) of 35.7 °C and 43.9 J g⁻¹, respectively, making it a potential candidate for an ambient temperature adjustment textile phase change material (PCM). Polybutylene terephthalate (PBT) was selected as the matrix and blended at different weight ratios of PBHA-C5, and the blended samples showed comparable T_m and ∆H_m after three cycles of cooling and reheating, indicating good maintenance of their phase changing ability. Samples were then processed via melt spinning with a take-up speed of 200 m min⁻¹ at draw ratios (DR) of 1.0 to 3.0 at 50 °C. The fiber’s mechanical strength could be enhanced to 2.35 g den⁻¹ by increasing the DR and lowering the PBHA-C5 content. Infrared thermography showed that a significant difference of more than 5 °C between PBT and other samples was achieved within 1 min of heating, indicating the ability of PBHA-C5 to adjust the temperature. After heating for 30 min, the temperatures of neat PBT, blended samples with 27, 30, and 33 wt% PBHA-C5, and neat PBHA-C5 were 53.8, 50.2, 48.3, 47.2, and 46.5 °C, respectively, and reached an equilibrium state, confirming the temperature adjustment ability of PBHA-C5 and suggesting that it can be utilized in thermoregulating applications.

The Impact of Artificial Marble Wastes on Heat Deflection Temperature, Crystallization, and Impact Properties of Polybutylene Terephthalate

As artificial marble is abundant and widely used in residential and commercial fields, the resource utilization of artificial marble wastes (AMWs) has become extremely important in order to protect the environment. In this paper, polybutylene terephthalate/artificial marble wastes (PBT/AMWs) composites were prepared by melt blending to maximize resource utilization and increase PBT performance. The research results showed that the filling of AMWs was beneficial to the improvement of PBT-related performance. X-ray diffraction analysis results indicated that after filling AMWs into the PBT matrix, the crystal structure of PBT was not changed. Heat deflection temperature (HDT) analysis results indicated that the HDT of PBT composites with 20 wt% AMWs reached 66.68 °C, which was 9.12 °C higher than that of neat PBT. Differential scanning calorimetry analysis results showed that heterogeneous nucleation could be well achieved when the filling content was 15 wt%; impact and scanning electron microscope analysis results showed that due to the partial core-shell structure of the AMWs, the impact strength of PBT was significantly improved after filling. When the filling amount was 20 wt%, the impact strength of the PBT composites reached 23.20 kJ/m², which was 17.94 kJ/m² higher than that of neat PBT. This research will not only provide new insights into the efficient and high-value utilization of AMWs, but also provide a good reference for improved applications of other polymers.

Poly(butylene succinate-co-butylene acetylenedicarboxylate): Copolyester with Novel Nucleation Behavior

Big spherulite structure and high crystallinity are the two main drawbacks of poly(butylene succinate) (PBS) and hinder its application. In this work, a new type of copolyester poly(butylene succinate-co-butylene acetylenedicarboxylate) (PBSAD) is synthesized. With the incorporation of acetylenedicarboxylate (AD) units into PBS chains, the crystallization temperature and crystallinity are depressed by excluding AD units to the amorphous region. In contrast, the primary nucleation capability is significantly strengthened, without changing the crystal modification or crystallization kinetics, leading to the recovery of total crystallization rate of PBSAD under the same supercooling condition. The existence of specific interaction among AD units is found to be crucial. Although it is too weak to contribute to the melt memory effect at elevated temperature, the interaction continuously strengthens as the temperature falls down, and the heterogeneous aggregation of AD units keeps growing. When the aggregating process reaches a certain extent, it will induce the formation of a significant amount of crystal nuclei. The unveiled nucleation mechanism helps to design PBS copolymer with good performance.

Synthesis, Characterization and Non-Isothermal Crystallization Kinetics of a New Family of Poly (Ether-Block-Amide)s Based on Nylon 10T/10I

A series of novel thermoplastic elastomers based on (poly(decamethylene terephthalamide/decamethylene isophthalamide), PA10T/10I) and poly(ethylene glycol) (PEG) were synthesized via a facile one-pot, efficient and pollution-free method. The thermal analysis demonstrates that the melting points of the resultant elastomers were in the range of 217.1-233.9 °C, and their initial decomposition temperatures were in the range of 385.3-387.5 °C. That is higher than most commercial polyamide-based thermoplastic elastomers. The tensile strength of the resultant elastomers ranges from 21.9 to 41.1 MPa. According to the high-temperature bending test results, the resultant samples still maintain considerably better mechanical properties than commercial products such as Pebax® 5533 (Arkema, Paris, France), and these novel thermoplastic elastomers could potentially be applied in high-temperature scenes. The non-isothermal crystallization kinetics of the resultant elastomers and PA10T/10I was investigated by means of Jeziorny and Mo's methods. Both of them could successfully describe the crystallization behavior of the resultant elastomers. Additionally, the activation energy of non-isothermal crystallization was calculated by the Kissinger method and the Friedman equation. The results indicate that the crystallization rates follow the order of TPAE-2000 > TPAE-1500 > PA10T/10I > TPAE-1000. From the crystallization analysis, the crystallization kinetics and activation energies are deeply affected by the molecular weight of hard segment.