Observation of a new high-temperature transition in polytetrafluoroethylene

Khanna, Y. P.; Chomyn, Georgette; Kumar, Rakesh; Murthy, N. Sanjeeva; O'Brien, Kennedy P.; Reimschuessel, A. C.

doi:10.1021/ma00211a015

Cited by 16 publications

(9 citation statements)

References 4 publications

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“…41) but may vary depending on material state, prehistory, irradiation dose, etc. [45][46][47] In this context, DSC testing of new PTFEcontaining composite materials around T m becomes Fig. 11 High-resolution 19 F NMR spectra of composites I (1), II (2) (for details see Table 4) and commercial PTFE (3).…”

Section: Dsc Curvesmentioning

confidence: 99%

Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization

et al. 2015

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Section: Dsc Curvesmentioning

confidence: 99%

Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization

et al. 2015

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“…PTFE molding powder is compressed into billets and sintered at high temperature (340-380 8C) prior to skiving sheets or machining parts [1,3]. On a laboratory scale, PTFE can be extruded using a capillary rheometer [4], while special PTFE bimodal molecular weight blends can be melt processed [5].…”

Section: Introductionmentioning

confidence: 99%

Supercritical CO2 processing and annealing of polytetrafluoroethylene (PTFE) and modified PTFE for enhancement of crystallinity and creep resistance

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et al. 2005

Polymer

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“…The X-ray diffraction (XRD) results in Figure 6a-c show two reflection peaks at Bragg angles of 24 • 2θ (3.7 Å) and 21 • 2θ (4.2 Å), related to the reflections of the crystalline planes (002)/(202) and ( 200) respectively, referring to monoclinic α-phase with higher tensile strength [27,28]. The reflection peak at a diffraction angle of 21 • , which corresponded to the γ-form of PA6, started appearing in the samples containing an EtMgBr concentration (Figure 6a) higher than 50%, pointing towards the loss of tensile strength.…”

Section: X-ray Diffraction Studymentioning

confidence: 99%

Optimising Crystallisation during Rapid Prototyping of Fe3O4-PA6 Polymer Nanocomposite Component

2022

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Polymer components capable of self-healing can rapidly be manufactured by injecting the monomer (ε-caprolactam), activator and catalyst mixed with a small amount of magnetic nanoparticles into a steel mould. The anionic polymerisation of the monomer produces a polymer component capturing magnetic nanoparticles in a dispersed state. Any microcracks developed in this nanocomposite component can be healed by exposing it to an external alternating magnetic field. Due to the magnetocaloric effect, the nanoparticles locally melt the polymer in response to the magnetic field and fill the cracks, but the nanoparticles require establishing a network within the matrix of the polymer through effective dispersion for functional and uniform melting. The dispersed nanoparticles, however, affect the degree of crystallinity of the polymer depending on the radius of gyration of the polymer chain and the diameter of the magnetic nanoparticle agglomerates. The variation in the degree of crystallinity and crystallite size induced by nanoparticles can affect the melting temperature as well as its mechanical strength after testing for applications, such as stimuli-based self-healing. In the case of in situ synthesis of the polyamide-6 (PA6) magnetic nanocomposite (PMC), there is an opportunity to alter the degree of crystallinity and crystallite size by optimising the catalyst and activator concentration in the monomer. This optimisation method offers an opportunity to tune the crystallinity and, thus, the properties of PMC, which otherwise can be affected by the addition of nanoparticles. To study the effect of the concentration of the catalyst and activator on thermal properties, the degree of crystallinity and the crystallite size of the component (PMC), the ratio of activator and catalyst is varied during the anionic polymerisation of ε-caprolactam, but the concentration of Fe3O4 nanoparticles is kept constant at 1 wt%. Differential Scanning Calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), XRD (X-ray diffraction) and Thermogravimetric analysis (TGA) were used to find the required concentration of the activator and catalyst for optimum properties. It was observed that the sample with 30% N-acetyl caprolactam (NACL) (with 50% EtMgBr) among all of the samples was most suitable to Rapid Prototype the PMC dog-bone sample with the desired degree of crystallinity and required formability.

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Observation of a new high-temperature transition in polytetrafluoroethylene

Cited by 16 publications

References 4 publications

Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization

Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization

Supercritical CO2 processing and annealing of polytetrafluoroethylene (PTFE) and modified PTFE for enhancement of crystallinity and creep resistance

Optimising Crystallisation during Rapid Prototyping of Fe3O4-PA6 Polymer Nanocomposite Component

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Observation of a new high-temperature transition in polytetrafluoroethylene

Cited by 16 publications

References 4 publications

Polymer composites prepared by low-temperature post-irradiation polymerization of C2F4 in the presence of graphene-like material: synthesis and characterization

Polymer composites prepared by low-temperature post-irradiation polymerization of C2F4 in the presence of graphene-like material: synthesis and characterization

Supercritical CO2 processing and annealing of polytetrafluoroethylene (PTFE) and modified PTFE for enhancement of crystallinity and creep resistance

Optimising Crystallisation during Rapid Prototyping of Fe3O4-PA6 Polymer Nanocomposite Component

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Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization

Polymer composites prepared by low-temperature post-irradiation polymerization of C₂F₄ in the presence of graphene-like material: synthesis and characterization