Rapid compression preparation and characterization of oversized bulk amorphous polyether-ether-ketone

Yuan, Chaosheng; Hong, Shiming; Li, X X; Shen, Ru; He, Zhongyi; Lv, Shaohui; Liu, X R; Lv, Juan; Xi, Daikun

doi:10.1088/0022-3727/44/16/165405

Cited by 14 publications

(20 citation statements)

References 30 publications

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“…For instance, Hong et al found that RC process could induce two amorphous phases of poly (ethylene terephthalate) (PET) which were different from that in quenched samples. Yu et al reported that the glassy sulfur obtained by RC process exhibited an exceptional thermodynamic and kinetic stability, and Yuan et al reported that the glassy polyether‐ether‐ketone samples prepared by RC exhibited high thermodynamic stability, excellent friction, and considerable stiffness in contrast to that prepared by quench cooling. In fact, it is increasingly believed that the glassy sample is in local‐ordered state with chain aggregation instead of perfectly amorphous state, and this local structure can exist while still providing a random large‐scale chain configuration .…”

Section: Introductionmentioning

confidence: 99%

Cold crystallization behavior of glassy poly(lactic acid) prepared by rapid compression

Zhang

Shao

et al. 2014

Polym Eng Sci

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The cold crystallization behavior of glassy poly(lactic acid) was studied by comparison among samples obtained through three different treatments, which are naturally cooling (NC), liquid nitrogen quenching (NQ), and rapidly compressing (RC). The crystallization kinetics and structural changes of these glassy samples were analyzed by using in situ Fourier transform infrared (FTIR) and in situ wide angle X-ray diffraction measurements. The results reveal that, the cold crystallization behavior is very similar between NC and NQ samples, but RC sample exhibits higher crystallization rate and lower crystallization temperature than them. FTIR investigation showed that, during the heating process for all the glassy samples, conformational adjustment in the amorphous phase occurs first, and followed by formation of the disordered crystals and then the disordered crystals further perfecting, while for RC sample the onset temperature of each step is much lower. Furthermore, for RC sample, the crystal grain number is larger and its initial a 0 form crystal induced by the heating is higher ordered than that of the others, and this unique crystallization behavior might be caused by the local ordered domains formed during the RC process. POLYM. ENG. SCI., 55:359-366, 2015. FIG. 6. Temperature dependence of the FTIR spectra in the 835-980 cm 21 range and the intensity change of indicated bands with temperature during cold crystallization.

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Section: Introductionmentioning

confidence: 99%

Cold crystallization behavior of glassy poly(lactic acid) prepared by rapid compression

Zhang

Shao

et al. 2014

Polym Eng Sci

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“…Furthermore, as shown in Figure A,B, a pronounced post‐ Tg endothermic peak is observed for the amorphous PLLA obtained under 200 to 400 MPa. Previous research have shown that the post‐ Tg endothermic peak could be assigned to the melting of the mesocrystal with certain chain ordering . Therefore, we speculate that the mesocrystal of PLLA could be formed during the compression process.…”

Section: Resultsmentioning

confidence: 76%

“…As mentioned above, it is found that there exists a critical formation pressure of amorphous PLLA in the crystallization process. Recently, it is reported that the amorphous materials can be obtained under pressure by the rapid compression method, and this approach is dependent on the higher pressure and the faster compression rate. Shao et al reported the preparation of amorphous PLLA by solidification under 2.0 GPa at a compression rate of 100 GPa/s.…”

Section: Resultsmentioning

confidence: 99%

Isothermally crystallization behavior of poly (L‐lactide) from melt under high pressure

Yuan

Yang

et al. 2018

Polymers for Advanced Techs

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The poly (L-lactide) (PLLA) samples from melt were isothermally crystallized at 175°C and 190°C under pressures (P C ) ranging from 0.1 to 400 MPa. The crystalline structures and thermal properties were investigated by using wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). On the basis of the DSC and WAXD results, it is confirmed that an α crystal was formed in the low-pressure region (P C ≤ 50 MPa), and the disordered α crystal (α′) was formed in the medium-pressure region (100 MPa ≤ P C ≤ 200 MPa) for the PLLA samples isothermally crystallized at 175°C. However, the only α crystal was formed in the pressure range from 0.1 to 200 MPa, and no α′ crystal could be found in the PLLA samples isothermally crystallized at 190°C. Interestingly, the full amorphous PLLA was obtained at 175°C and 190°C, when the P C was above 250 MPa. There seems to exist a cut-off pressure for the crystallization of PLLA, which divides the pressure into high and low regions.The peculiarities of crystalline structure could be explained by the enhanced melt supercooling and the confined crystallization behaviors of PLLA under high pressure.The effect of the compression rate on the formation of amorphous PLLA was also researched with different compression rates. The results indicate that the molten PLLA could be easy to solidify as full amorphous phase under the higher pressure at a lower critical compression rate. KEYWORDS high pressure, isothermally crystallization, melt, PLLA | INTRODUCTIONWith the development of polymer science, plastics bring us civilized conveniences. However, a large amount of waste plastics have been a serious environmental problem. We live in the plastic age (the "plasticene"), producing over 300 million tons (mt) of plastic every year globally, 5 to 15 mt of which flow into already polluted oceans. 1 Poly (L-lactide) (PLLA) has received much attention over the past few decades, because it is renewable, nontoxic, biodegradable, and biocompatible. [2][3][4] Furthermore, PLLA has unique properties, such as high modulus, high strength, and good clarity. Therefore, it has been widely applied in the fields of packing textile, and tissue engineering, making it one of the most potential alternatives for petroleum-based commodity polymers. 5,6 Due to its limited application because of its brittleness at room temperature, PLLA is usually blended with plasticizers to modify the brittle behavior for improving the application performance. 7,8 In contrast with the aforementioned approaches, regulating the crystalline structure and morphology of PLLA through controlling crystallization conditions can also effectively improve its impact resistance but can avoid aforementioned problems.Poly (L-lactide) is known to form three kinds of crystal modification, namely, the α, 9 β, 10 and γ 11 forms, along with a new α crystal modification, named the α′ form. 12 The resulting formation of crystal structure depends on various processing conditions, including temperature, shearing, and stretching. The most co...

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“…In this case, the generation of mesophase is very likely be favored . Actually, with pressurization, the formation of metastable structures has been observed for different kinds of polymers . Therefore, pressurization can induce more effects than temperature cooling (i.e., obtaining of undercooling) on crystallization, like inducing appearance of metastable structure.…”

Section: Resultsmentioning

confidence: 99%

High‐pressure induced formation of isotactic polypropylene mesophase: Synergistic effect of pressure and pressurization rate

Huang

Shao

et al. 2018

Polymer Engineering & Sci

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The crystallization induced by high pressures up to 2 GPa was studied for isotactic polypropylene (iPP) using wide angle X-ray diffraction, small angle X-ray scattering, and atomic force microscopy methods. The iPP mesophase can be induced at 200 C by high pressures with fast pressurization rate. A pressure-pressurization rate kinetic phase diagram of mesophase and γ-phase was established to systematically analyze the influences of pressure and pressurization rate on crystallization polymorphism. Under pressure not higher than 0.75 GPa, only γ-phase is formed, even the pressurization rate reaches 5 × 10 3 MPa/s. With increasing pressure to 1.0 GPa, the mesophase is possible to be generated. As pressure further increases to 1.5 GPa and higher, the pure mesophase system can be obtained for pressurization rate above the critical values (about 10 MPa/s). Moreover, the structure of iPP mesophase obtained by rapid pressurization was analyzed and compared with that prepared by temperature quenching. Also interestingly, the pressure-induced mesophase can transform into γ-phase by annealing under pressure at 200 C, and the rate of this phase transition is slowed down with increasing annealing pressure. POLYM. ENG. SCI., 59:439-446, 2019.

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Rapid compression preparation and characterization of oversized bulk amorphous polyether-ether-ketone

Cited by 14 publications

References 30 publications

Cold crystallization behavior of glassy poly(lactic acid) prepared by rapid compression

Cold crystallization behavior of glassy poly(lactic acid) prepared by rapid compression

Isothermally crystallization behavior of poly (L‐lactide) from melt under high pressure

High‐pressure induced formation of isotactic polypropylene mesophase: Synergistic effect of pressure and pressurization rate

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