Electrical conductivity of waxes as model systems for polyethylene: Role of water

Hosier, I. L.; Vaughan, A. S.; Quirke, N.

doi:10.1002/app.48765

Cited by 8 publications

(6 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As such, DC conductivity values were first estimated from each data set by averaging the final 10 data points obtained ( σ DC1 ). Second, the time dependent conductivity, σ ( t ), data shown were fitted to a modified form of the Curie‐Von Schweidler law [22], which incordsporates a steady state, DC conductivity term, σ DC2 :

σ (t) = σ_{D C 2} + a t^{‐ b}

…”

Section: Resultsmentioning

confidence: 99%

Dielectric behaviours of bio‐derived epoxy resins from cashew nutshell liquid

Vaughan

2020

High Voltage

Self Cite

View full text Add to dashboard Cite

In this study, four commercially available bio‐derived epoxy systems (extracted from cashew nutshell liquid) were prepared and characterised. The glass transition temperature (T g), dielectric spectroscopy, DC conductivity and breakdown properties of these epoxy resins were studied. Differential scanning calorimetry (DSC) demonstrated that the T g of the investigated systems ranged from 67 to 122°C. The DC conductivity was very low (<10−16 S cm−1) and comparable to the conventional dielectrics at room temperature (RT). However, all systems showed a strong temperature dependence of the electrical conductivity and exhibited sharp increase around their respective T g. Arrhenius analysis led to activation energy, E a, values around 1 eV; higher E a values were observed in systems with a lower T g. Dielectric spectroscopy revealed a flat and low response at temperature below T g. However, both the real and imaginary permittivity increased with decreasing frequency at mid to low frequencies as the temperatures approached T g. The variations of AC breakdown strength of all samples were not statistically significant, but the DC breakdown strength of sample 2503A + 2002B was higher than the others, which might be due to reduced charge transport in this system. The results indicate that novel bio‐derived epoxy systems from renewable sources are potential alternatives for traditional petroleum‐based epoxy systems in certain insulation applications.

show abstract

σ (t) = σ_{D C 2} + a t^{‐ b}

…”

Section: Resultsmentioning

confidence: 99%

Dielectric behaviours of bio‐derived epoxy resins from cashew nutshell liquid

Vaughan

2020

High Voltage

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although waste polyethylene wax and its blends have not been extensively studied in the literature, there are many studies regarding various other waxes and their blends with other material 4–7 . Paraffin wax has been used as model systems for polyethylene for studying electrical conductivity, and the conductivity of wax has been studied since 1932 8 . The blends of wax and polyethylene have drawn attention to themselves since they have many valuable properties such as lightweight, good processability, and low cost 9 .…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7] Paraffin wax has been used as model systems for polyethylene for studying electrical conductivity, and the conductivity of wax has been studied since 1932. 8 The blends of wax and polyethylene have drawn attention to themselves since they have many valuable properties such as lightweight, good processability, and low cost. 9 The primary application of these blends is as phase change material (PCM).…”

Section: Introductionmentioning

confidence: 99%

Morphology, phase diagram, and properties of high‐density polyethylene/thermally treated waste polyethylene wax blends

Esmaeilzade

Sharif

Rashedi

et al. 2021

J of Applied Polymer Sci

View full text Add to dashboard Cite

Waste polyethylene wax is thermally treated using a rotary evaporator to reduce unwanted components. Fourier transform infrared proves the absence of undesirable material. Wax is extruded with high‐density polyethylene (HDPE) at various loadings to study its morphology and final properties. Scanning electron microscopy and differential scanning calorimeter were employed to obtain the phase diagram showing the immiscibility of blends containing more than 20 wt% of wax. Due to the low melting temperature of the wax and its plasticating effect on HDPE, a decrease in melting temperature, enthalpy of fusion, and crystallinity with increasing wax content of the blend is observed. The phase diagram displays four possible phases depending on temperature and wax loading. Improved processability of HDPE/wax blends is demonstrated using complex viscosity curves. Han plots prove the miscibility of wax and HDPE in the melt state even at high concentrations of wax. HDPE/wax compounds have lower crystallinity, and wax particles, acting as weak spots, lower the elastic modulus, yield stress, and stress and strain at break as wax content increases. An increase in yield strain is observed due to the more effortless extension of HDPE chains at higher wax content. In 10 wt% of wax is accepted as the upper limit for wax incorporation into the HDPE matrix.

show abstract

“…In seeking to estimate a DC conductivity value from such data, a number of strategies are possible, such as averaging a number of current measurements obtained within the apparently steady‐state regime, or fitting the raw data to some suitable function. Recently, Hosier et al [48] contrasted these two approaches and reported that, for their systems, the use of the Curie von Schweidler law [49] modified by the addition of a time‐independent steady‐state DC conduction term led to more reliable DC conductivity values. As such, the same approach was used here, but, in this case, the results were found to fall within the uncertainties associated with direct current measurements.…”

Section: Ageing Morphology and Charge Transportmentioning

confidence: 99%

Ageing behaviour of a polyethylene blend: influence of chemical defects and morphology on charge transport

2020

View full text Add to dashboard Cite

The properties of novel cable insulation systems will rely critically upon the morphology of the material. Here, a blend of high and low-density polyethylene (PE) was processed in order to generate three sets of samples with different morphologies. The influence of thermo-oxidative ageing at 120°C was then considered. The resulting chemical changes included the introduction of unsaturation and oxygen-containing groups and were determined by antioxidant consumption and oxygen permeability. Such chemical defects were found to be concentrated in the fraction of each system that was molten at 120°C and, consequently, served to inhibit recrystallisation following ageing. The resulting spatial distribution of charge trapping sites was therefore strongly dependent on morphology. The electrical conductivity of each system varied non-monotonically with ageing: short times reduced the conductivity; a rapid increase in conductivity over five orders of magnitude occurred beyond a critical ageing threshold. Despite the pronounced structural differences between the morphologically distinct sets of samples, all exhibited comparable conductivity values beyond this threshold, implying that while charge transport is strongly influenced by chemical factors, crystallinity is relatively unimportant. This experimental finding appears at odds with theoretical studies of the electronic states in crystalline and amorphous PE.

show abstract

Electrical conductivity of waxes as model systems for polyethylene: Role of water

Cited by 8 publications

References 36 publications

Dielectric behaviours of bio‐derived epoxy resins from cashew nutshell liquid

Dielectric behaviours of bio‐derived epoxy resins from cashew nutshell liquid

Morphology, phase diagram, and properties of high‐density polyethylene/thermally treated waste polyethylene wax blends

Ageing behaviour of a polyethylene blend: influence of chemical defects and morphology on charge transport

Contact Info

Product

Resources

About