Copolymerization of hexafluoropropylene and tetrafluoroethylene: Effect on chain conformation and crystal structure

Correlations between microstructure and crystallization of the fluorinated terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride

“…In this picture, the size achievable for the growing crystals is limited because they impinge on the rigid AAO pore walls. Considering the frustration of the growth of PTFE‐like THV crystals by the presence of HFP units already under bulk conditions reported previously, it is reasonable to assume that THV crystals are so small that they do not experience hard confinement by the AAO pore walls. The long period of 12 nm found for crystals consisting of a THV grade with similar composition than THV‐221G in the bulk corroborates this notion.…”

“…For FEP copolymer containing 25 mol % HFP, WAXS patterns showed two overlapping peaks, resulting in a scattering intensity profile similar to those seen in Figure . A peak at 2Θ = 17.4° was assumed to represent TFE‐rich crystals with smaller d‐ spacing, whereas a peak at 2Θ = 16.2° was assumed to represent HFP‐rich crystals with a d‐ spacing enlarged by the incorporation of the HFP units into the crystals . For THV containing 52 mol % VDF, 36 mol % TFE, and 12 mol % HFP, WAXS patterns showed a reflection at 2Θ ~18°, whereas small‐angle X‐ray scattering on melt‐crystallized samples revealed a lamellar long period of 12 nm .…”

Controllable design of polytetrafluoroethylene chemical component using the “harmful” irradiation heat

“…The changes of the aggregate structure were caused by the functional groups (COF, COOH, and CF 3 ) generated during the irradiation process. These groups were attached to the surface of the macromolecular fragments produced by chain scission, and partly inserted into the crystalline region to break the regularity of the crystal, then caused more crystallization defects, which made the lattice parameters increase 44,45 . Therefore, the interplanar distance and crystallite size of the irradiated PTFE would increase compared with the unirradiated samples.…”

“…These groups were attached to the surface of the macromolecular fragments produced by chain scission, and partly inserted into the crystalline region to break the regularity of the crystal, then caused more crystallization defects, which made the lattice parameters increase. 44,45 Therefore, the interplanar distance and crystallite size of the irradiated PTFE would increase compared with the unirradiated samples. According to the above relationship between degradation index and irradiation dose (Figure 4), it could be concluded that both increased irradiation dose and shortened interval time could lead to an increase in the number of functional groups, and the effect of shortening the interval time was more significant.…”

Modification of carbon nanotubes with fluorinated ionic liquid for improving processability of fluoro-ethylene-propylene

“…Three diffraction peaks of (100), (110), and (200) could be observed in the 2-D diffraction patterns which were attributed to the typical crystal structure of FEP [7,26,27],…”