Synthesis, characterization and crystallization kinetics of nanocomposites prepared by in situ polymerization of ethylene and graphene

Shehzad, Farrukh; Daud, Muhammad; Al‐Harthi, Mamdouh A.

doi:10.1007/s10973-015-5087-x

Cited by 20 publications

(15 citation statements)

References 44 publications

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“…Graphene sheets are composed of sp 2 hybridized carbon atoms linked in hexagonal structure with each carbon atom covalently bonded to three other carbon atoms [4]. So far, researchers have mainly focused on the effect of graphene content on the nucleation of thermally conductive high-density polyethylene (HDPE) nanocomposites at small supercooling [5], the functionalization and preparation methods of polyethylene, the improvement of thermal stability [6][7][8][9][10][11][12], and the study of mechanical properties of composites [13,14]. However, there is limited literature available on the effect of graphene size on thermal properties of polyethylene [12,[15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Insights into crystallization and melting of high density polyethylene/graphene nanocomposites studied by fast scanning calorimetry

et al. 2018

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Vourlias, G. (2018). Insights into crystallization and melting of high density polyethylene/graphene nanocomposites studied by fast scanning calorimetry. Polymer Testing, 67,[349][350][351][352][353][354][355][356][357][358] AbstractGraphene nanoplatelets (5 wt.%) with different diameters (5 and 25 x 10 -6 m in diameter, 6 x 10 -9 m in thickness) filled high density polyethylene nanocomposites were prepared by the melt-mixing method and the effect of graphene nanoplatelets on the polymeric matrix are then investigated by X-ray diffraction, polarized light microscopy, differential scanning calorimetry, fast scanning calorimetry, and rheology. Polarized light microscopy revealed that graphene nanoplatelets of 5 x 10 -6 m promote the decrease in the size of the spherical aggregates during crystallization compared to larger nanoplatelets. From rheological measurements, it was found that even though the viscosity of the nanocomposites with increasing filler diameter was increased significantly compared to the neat polymer, the processability of these 2 materials was not affected. Several melting events for neat high-density polyethylene and graphene nanocomposites were observed by fast scanning calorimetry associated with the small imperfect crystals grown at large supercooling, the nucleation efficiency and the diameter size of the filler. The activation energy values versus the relative extent of crystallization revealed that graphene nanoplatelets block the movement of the molecular segments and make crystallization difficult, especially at the final stage of the process. Based on this work, it can be concluded that the nanocomposite with the smaller diameter showed the most enhanced crystallization kinetics as graphene increased the number of nucleation sites, while the larger ones hindered the melted molecules in reaching full isotropization above the melting temperature. determined by conventional DSC (filled symbols) and FSC (open symbols)

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Section: Introductionmentioning

confidence: 99%

Insights into crystallization and melting of high density polyethylene/graphene nanocomposites studied by fast scanning calorimetry

et al. 2018

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“…The mass fraction is related to the time and temperature by the following relation [eq. ] :

α_{i} ((), T) = \frac{Δ H ((), T)}{{Δ H}_{italictotal}} = \frac{{[\int_{T_{o}}^{T + dT} (\frac{dH}{dT}) dT]}_{i + 1} - {[\int_{T_{o}}^{T} (\frac{dH}{dT}) dT]}_{i}}{\int_{T}^{T_{\infty}} ((), \frac{italicdH}{italicdT}) italicdT}

…”

Section: Resultsmentioning

confidence: 99%

“…HDPE and HDPE/graphene nanocomposites were synthesized by in situ polymerization. The materials and the detailed synthesis procedures are described in our previous articles . Nanocomposites containing graphene were prepared with three different compositions, that is, 0.15, 0.25, and 0.40 wt % of graphene.…”

Section: Methodsmentioning

confidence: 99%

Photooxidative degradation of graphene‐reinforced high‐density polyethylene nanocomposites

Shehzad

Ahmad

Al‐Harthi

2018

J of Applied Polymer Sci

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Natural weathering of high-density polyethylene (HDPE) and its graphene nanocomposites was studied. The nanocomposites, prepared by in situ polymerization of ethylene, were exposed to the natural environment for 30, 60, and 90 days. The effects of weathering on the crystallinity, melting temperature, and lamellar thickness distribution were studied using differential scanning calorimetry. The changes in chain microstructure and molecular weight were determined by crystallization analysis fractionation and gel permeation chromatography, respectively. The effects of weathering on the dynamic mechanical properties and the morphology of the nanocomposite were also determined. The parent HDPE suffered severe degradation as expected. However, graphene-reinforced HDPE nanocomposites show resistance to degradation. The changes in the crystallinity, lamellar thickness, molecular weight, and dynamic mechanical properties of graphene nanocomposites were less pronounced as compared to the parent HDPE.

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“…Therefore, the knowledge of polymer crystallization kinetics and resulting degree of crystallinity are helpful tools for its processing and desired characteristics . Several studies have been done for better understanding of the concepts linked with isothermal and non‐isothermal crystallization behaviour of PE . The non‐isothermal crystallization kinetics has more practical significance over the isothermal kinetics study due to its industrial applications .…”

Section: Introductionmentioning

confidence: 99%

“…[11,12] Several studies have been done for better understanding of the concepts linked with isothermal and non-isothermal crystallization behaviour of PE. [13,14] The non-isothermal crystallization kinetics has more practical significance over the isothermal kinetics study due to its industrial applications. [15] These non-isothermal melt studies successfully cover a wide range of kinetic models including Jeizorny, Ozawa, and Mo models [16][17][18] for the HDPE, LDPE, and LLDPE.…”

Section: Introductionmentioning

confidence: 99%

Crystallization behaviour and lamellar thickness distribution of metallocene‐catalyzed polymer: Effect of 1‐alkene comonomer and branch length

2016

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The effect of comonomer and branching on the melt crystallization and lamellar thickness distribution was studied for ethylene and 1‐alkene copolymers. The comonomers used in this study are 1‐hexene, 1‐octene, and 1‐decene. A notable influence of the comonomer ratio in the feed was observed on the crystallization and melting behaviour. The Ozawa and Mo models were found suitable for these copolymers. However, variation of relative crystallinity at different heating rates preferred the Mo method over the Ozawa method. The melting behaviour and lamellar thickness distribution of the copolymers were analyzed by the help of the modified Gibbs‐ Thomson equation. The activation energies (EA) for the melt crystallization were calculated using the Kissinger method. It was observed that 1‐hexene comonomer exhibits lower EA, indicating an easier crystallization process as compared to other comonomers used. Overall, crystallization was found to be more influenced by the degree of branching rather than the comonomer type.

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Synthesis, characterization and crystallization kinetics of nanocomposites prepared by in situ polymerization of ethylene and graphene

Cited by 20 publications

References 44 publications

Insights into crystallization and melting of high density polyethylene/graphene nanocomposites studied by fast scanning calorimetry

Insights into crystallization and melting of high density polyethylene/graphene nanocomposites studied by fast scanning calorimetry

Photooxidative degradation of graphene‐reinforced high‐density polyethylene nanocomposites

Crystallization behaviour and lamellar thickness distribution of metallocene‐catalyzed polymer: Effect of 1‐alkene comonomer and branch length

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