The melting temperature range of polymers

Gasparyan, K.A.; Borokhonovskii, V.A.; Sevast'yanov, L.K.; Mirzoyev, R.G.; Баранов, В. Г.

doi:10.1016/0032-3950(76)90258-6

Cited by 3 publications

(3 citation statements)

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“…In addition, the diffraction peaks had a slight shift, which indicated that the distance between crystal planes may be influenced by heat aging. It should be emphasized that the diffraction peaks of FDY shifted more seriously than that of UVFDY, which also illustrated that the crosslinked structure restricted the regular rearrangement of molecules in amorphous phase, so that high temperature played an insignificance role on crystalline interplanar spacing of UVFDY 31 …”

Section: Resultsmentioning

confidence: 99%

“…It should be emphasized that the diffraction peaks of FDY shifted more seriously than that of UVFDY, which also illustrated that the crosslinked structure restricted the regular rearrangement of molecules in amorphous phase, so that high temperature played an insignificance role on crystalline interplanar spacing of UVFDY. 31 The X C,W of FDY and UVFDY at different aging time were calculated by Equation 2 (Figure 4c). It presented that the X C,W of FDY and UVFDY also decreased after short time aging (<2 h) and then increased when the aging time exceeded 2 h, which trends corresponded to that of X C,D .…”

Section: Waxd Analysismentioning

confidence: 99%

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Thermal aging behavior and heat resistance mechanism of ultraviolet crosslinked ultra‐high molecular weight polyethylene fiber

Dong,

Niu,

Qiang

et al. 2024

J of Applied Polymer Sci

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As advances in heat resistant ultrahigh molecular weight polyethylene (UHMWPE) fiber via ultraviolet (UV) crosslinking, it is worth paying attention to its thermal aging behavior and heat resistance mechanism. UHMWPE fibers in different forms, the fully drawn yarn (FDY) and the UV crosslinked FDY (UVFDY), are subjected to isothermal aging at 135°C. The effects of thermal aging on their surface morphology and mechanical properties are studied and compared initially. The results demonstrate that UVFDY is a kind of a heat‐resistant fiber. Subsequently, to reveal the heat resistance mechanism of UVFDY, its crystalline and orientation structure evolution during thermal aging are further studied. It is indicated that the formation of dense‐packing crystals and disorientation behavior lead to fiber shrink, so that a number of grooves appear on the fiber surface. Since the crosslinked stucture of UVFDY hinders its molecules movement, the crystallization and disorientation behavior of UVFDY are weaker than those of FDY, resulting in UVFDY possesses slighter thermal shrinkage (Ts), fewer grooves and better mechanical properties than those of FDY. Therefore, the heat resistance of the fiber improves effectively after UV crosslinking. This work provides insights into the structure–property relationship of UVFDY during thermal aging, and offers basis data for its application in specific conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Waxd Analysismentioning

confidence: 99%

Thermal aging behavior and heat resistance mechanism of ultraviolet crosslinked ultra‐high molecular weight polyethylene fiber

Dong,

Niu,

Qiang

et al. 2024

J of Applied Polymer Sci

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“…Based on the melting curves measured in the first heating phase, the crystallinity and melting range are calculated by using the following two equations [12], [20],…”

Section: A Annealing Effect On Thermal Performancementioning

confidence: 99%

Rejuvenation of Retired Power Cables by Heat Treatment: Experimental Simulation in Lab

et al. 2020

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In this work, heat treatment was performed on three retired 110 kV AC cables with service years of 0, 15 and 30, and the effects on the thermal and electrical performance of the cable insulation were investigated. First, each cable with a length approximately of 5 m was prepared and cut into five equal segments. Four segments of each cable were annealed at a temperature of 90, 95, 100, or 105 • C by building a small circuit to simulate cable operation. Then, a section at the middle of each segment was cut out, and the insulation layer was peeled away. The peeled-off layers from the inner, middle and outer positions were selected as the test samples. Subsequently, Fourier transform infrared spectrometry (FTIR), and differential scanning calorimetry (DSC) were performed, and the DC conduction current and dielectric breakdown strength were measured. The best thermal properties of the highest melting point, crystallinity, and smallest melting range were found when the cables were annealed at 100, 105, and 105 • C for the inner, middle, and outer positions, respectively. The highest dielectric breakdown strength and lowest electrical conductivity were found at temperatures of 95 or 100 • C for the inner and middle positions, respectively, and at 105 • C for the outer position. The FTIR results showed that thermal annealing for hundreds of hours did not adversely affect the molecular chains. It is found that this type of heat treatment could be a feasible method to rejuvenate retired cables, and a conservative temperature of 95 • C is regarded as the optimum annealing temperature. INDEX TERMS Cable, DSC, melting point, crystallinity, electrical conductivity, dielectric breakdown strength.

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