Simple Melt Blending Research Articles

Insulative ethylene-propylene copolymer-nanostructured polypropylene for high-voltage cable insulation applications

Worldwide, various efforts to replace crosslinked-polyethylene (XLPE) as an insulation layer in the cable industry, is becoming increasingly popular for improved recycling of polymer waste. Polypropylene (PP) has been proposed as a representative candidate because of its excellent thermomechanical and electrical performances. However, overcoming the mechanical limitations of intrinsic rigidity is required for cable applications. Herein, PP-based insulating materials were prepared via melt-blending with rubbery ethylene-1-octene copolymer (EOC), followed by mixing an ethylene-propylene random copolymer (rPP) as a surfactant for high-voltage power cable applications. Simple melt-blending of rPP formed a core-shell nanostructure composed of EOC/rPP and a fine dispersion of macron-sized EOC domains. The nanostructured PP ternary blends exhibited multiple advantages in terms of thermal stability, mechanical properties, dielectric performances, and long-term stability compared to the existing XLPE. This study provides a straightforward, rational design of environmental insulation materials for high voltage power cable applications.

Impact of Graphite on Thermomechanical, Mechanical, Thermal, Electrical Properties, and Thermal Conductivity of HDPE/Copper Composites

AbstractImpact of graphite on the physicochemical properties of high density polyethylene (HDPE)/copper composites has been investigated at various volume percentages of copper. The two sets of composites are prepared by simple melt blending and injection molding approach. Thermal conductivity increases from 0.5 W m−1 K−1 for pure HDPE to 6.5 and 8 Wm−1 K−1 for 30 and 40 vol.% of copper loading with and without graphite, respectively. A huge increment in synergistic efficiency has been evidenced for the mixed filled polymer composites. Incorporation of graphite has also improved the percolation threshold from 19 to 13 vol.% of copper loading to the HDPE matrix, which indicates the synergistic effect of mixed filler system. Development of leafy morphology of copper promotes large number of inter‐particle contacts and hence improves the percolation threshold of the composites. The corrosion resistive, mechanically robust, electrically and thermally conductive composites with good flexural properties and light in weight than conventional metallic bipolar plates suggest it a material of choice for fuel cell devices.

Preparation and Thermal Properties of Stearic Acid/n‐Octadecane Binary Eutectic Mixture as Phase Change Materials for Energy Storage

AbstractStearic acid/n‐octadecane (SA‐ODE) binary eutectic mixture was made by simple melt blending method and differential scanning calorimetry (DSC) was used to characterize the thermal properties of SA, ODE, and their binary mixtures. The phase diagram of SA‐ODE binary system displays a eutectic behavior and the corresponding mass percentage of SA at eutectic point is 4 wt%. The onset melting temperature (Ton) of binary eutectic mixture is 27.4°C, and the latent heat (ΔfusH) is 227 J g−1. The solid‐liquid phase transition temperature and the latent heat of fusion of SA‐ODE binary eutectic mixture have no obvious change after 100 repeated thermal cycles, which suggests the SA‐ODE binary eutectic mixture has good thermal durability and has potential as phase change materials for thermal energy storage.

Towards polylactide/core-shell rubber blends with balanced stiffness and toughness via the formation of rubber particle network with the aid of stereocomplex crystallites

As the most promising bio-derived and biodegradable polymers with tremendous application potential, the practical application of poly(l-lactide) (PLLA) has been severely restricted by its inherent brittleness. Unfortunately, blending with various rubbers can substantially enhance the toughness of PLLA, but usually causes a significant deterioration in mechanical strength and modulus. In this work, taking novel PLLA/core-shell rubber (CSR) blends as an example, we describe a facile and robust strategy to obtain good stiffness-toughness balance by promoting the networking of CSR particles within PLLA matrix with the aid of stereocomplex (SC) crystallites. To do this, small amounts (5–20 wt%) of poly(d-lactide) (PDLA) were incorporated into the blends through simple melt-blending. The results demonstrate that the CSR particles can be uniformly dispersed in PLLA matrix due to the good interfacial compatibility, but the stereocomplex (SC) crystallites formed between the incorporated PDLA and PLLA matrix chains induces the organization of the CSR particles into a network-like structure in the matrix. Compared with the well-dispersed structure, the network-like structure can endow the PLLA/CSR blends with dramatically enhanced impact toughness, without compromising their mechanical strength and modulus, indicating a marvelous balance between the stiffness and toughness. Furthermore, the elongation at break of the blends is also enhanced greatly. These interesting findings suggest that the formation of SC crystallites could provide a promising avenue for fabricating CSR particles toughened PLLA blends with balanced stiffness-toughness.

Effects of multi-walled carbon nanotubes (MWCNTs) on the degradation behavior of plasticized PLA nanocomposites

Polymer blend nanocomposites based on polylactic acid (PLA) were prepared via simple melt blending and investigated for its biodegradation behavior. The CNTs were surface-modified using acid treatment, and characterizations of composites were done using FTIR. FTIR spectra confirmed the surface modification of CNTs. The water uptake and weight loss behavior in hydrolytic analysis of CNT and m-CNT nanocomposites at different temperatures (25 and 45 °C) were studied. It was found that the water absorption and weight loss of nanocomposites increase by incorporation of CNTs and m-CNTs up to 2% for all samples, with and without PEG loading. In sample PLA/CNTs, 2% CNTs loading shows 1.18% water uptake at 25 °C and increases to 1.95% at 45 °C water immersion, whereas, in PLA/m-CNT nanocomposites, the water uptake reduces at 1.16% at 25 °C and 1.50% at 45 °C of analysis. In the meanwhile, the weight loss of 2% CNTs loading in PLA shows 2.88% at 25 °C and 6.28% at 45 °C, and for m-CNTs loading, the weight loss exhibits 2.09% at 25 °C and 5.29% at 45 °C. This proved the modified CNTs be able to retard the ability of nanocomposites degradation. The effect of plasticizer addition in nanocomposites was studied by loading 5 and 10% PEG. As expected, the inclusion of PEG enhanced the rate of degradation in both hydrolytic and soil burial studies. For the same amount of 2% CNTs inclusions and 10% PEG, at 45 C, the water uptake shows 5.56% as compared with 5% PEG loading, only 3.1% water uptake is shown. In soil burial test, the weight loss also increases with the addition of nanofiller. PLA/m-CNTs show lower weight loss which is only 4.50% and around 7.02% for PLA/CNTs nanocomposite. In the other hand, 10% PEG loading shows an increase in the weight loss in both CNT and m-CNT nanocomposites. Results from this study demonstrate that the inclusion of CNTs and m-CNTs into polymer matrix could increase the environmental persistence of polymers in lakes, landfills and surface waters.

The effect of MBS on the heat resistant, mechanical properties, thermal behavior and rheological properties of PLA/EVOH blend

This work focuses on improve the mechanical properties of poly(lactic acid)/poly(ethylene-co-vinyl alcohol) (PLA/EVOH) blend and simultaneously remained a high Vicat softening temperature (VST) using appropriate contents of methyl methacrylate–butadiene–styrene copolymer (MBS) via simple melt blending. The effects of MBS on the heat resistant, mechanical properties, thermal properties and rheological behavior were examined in detail with various techniques. The VST of neat PLA significantly increased to 159 °C from 66.8 °C after blending with 50 wt% EVOH. However, the VST was gradually decreased with increasing MBS content but were still much higher than that of neat PLA. On the basis of the tensile and impact tests results, PLA/EVOH/MBS blends showed a considerably higher elongation at break and impact strength. For all PLA/EVOH/MBS blends, the thermal stability was increased compared than that of PLA/EVOH blend without MBS. With increasing MBS content, the complex viscosity and storage modulus of PLA/EVOH blend increased, especially at low frequencies, indicating that MBS enhanced the chain entanglement in the PLA/EVOH matrix. In addition, the results Han curves and Cole–Cole plots indicated that the relaxation time was increased when MBS was added.

Preparation and properties of polyethylene glycol/unsaturated polyester resin/graphene nanoplates composites as form-stable phase change materials

In this study, a series of poly(ethylene glycol) (PEG)/unsaturated polyester resin (UPR)/graphene nanoplates (GNPs) form-stable PCMs (FS-PCMs) were prepared via a simple melt blending method. In this composite, PEG was used as the phase change material for thermal storage, UPR was introduced as a supporting material to prevent the leakage of melted PEG during the phase change transition and the GNPs were selected as conductive fillers to enhance the thermal conductivity of the polymer-based FS-PCMs. The test results demonstrate that the FS-PCMs exhibit an outstanding form-stable performance because of the cross-linked spatial network of UPR. According to the FT-IR and XRD results, no new chemical bonds form among PEG, UPR and the GNPs. The results obtained from TGA and DSC show that the composites possess an excellent thermal stability and a high energy storage density. Moreover, it is also found that the incorporation of GNPs remarkably enhances the thermal conductivity of the prepared FS-PCMs.

Crystallization behavior, rheology, mechanical properties, and enzymatic degradation of poly(L-lactide)/poly(D-lactide)/glycidyl methacrylate grafted poly(ethylene octane) blends

Poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA)/poly(ethylene octene) grafted with glycidyl methacrylate (GPOE) were prepared by simple melt blending method at PDLA loadings from 1 to 5 wt%. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) demonstrated the formation of the stereocomplex in the blends. The addition of PDLA led to the increase of nucleation density from polarized microscope (POM) observations. Rheological measurements indicated that the blends exhibited a rheological fluid-solid transition and an enhanced elastic behavior in that ternary system as the PDLA loadings reached up to 5 wt%. By adding 1-2 wt% PDLA, the ternary system has better tensile and impact properties. Dynamic Mechanical Analysis (DMA) results showed that SC crystal formation and its effect on the enhancement of thermal stability at higher temperature. It is interesting that the enzymatic degradation rates have been enhanced clearly in the PLLA/PDLA/GPOE blends than in the PLLA/GPOE blend, which may be of great use and significance for the wider practical application of PLLA/GPOE blends.

Facile preparation of rapidly electro-active shape memory thermoplastic polyurethane/polylactide blends via phase morphology control and incorporation of conductive fillers

Rapidly electro-active thermoplastic polyurethane (TPU)/polylactide (PLA) shape memory polymer (SMP) blends via phase morphology control and incorporation of conductive multi-walled carbon nanotubes (MWCNTs) were achieved by simple and efficient melt blending in this work. Binary TPU/PLA blends with various composition ratios were firstly prepared, and the effect of phase morphology on shape memory behavior was studied. The optimum shape memory behavior was observed for TPU50/PLA50 blends with co-continuous phase morphology. Then a small number of MWCNTs were selectively incorporated into TPU phase of TPU50/PLA50 and TPU60/PLA40 blends to realize electro-active shape memory effect. The formation of double percolation network imparted TPU/PLA/MWCNT conductive polymer composites with high electrical conductivities in low percolation thresholds, thus realized rapidly electro-active shape memory behaviors. Additionally, the mechanical properties of TPU/PLA blends (50/50, 60/40) can be enhanced by the addition of MWCNTs even at high temperature. Therefore, our work provides a simple way to fabricate polymer blends with rapid electro-active shape memory performances, good mechanical properties as well as good processing capability but low cost.

3D printing of tunable shape memory polymer blends

3D-printable tunable SMPs consisting of three kinds of cheap commercial polymers are prepared using a simple melt blending strategy.

TiO2 hybrid polypropylene/nickel coated glass fiber conductive composites for highly efficient electromagnetic interference shielding

A highly efficient electromagnetic interference shielding composite based on nickel coated glass fibers (NCGFs) and titanium dioxide (TiO2) filled polypropylene (PP) is fabricated via the simple melt blending method. Superior shielding effectiveness of 44.5 dB can be achieved with only 1.12 vol% Ni and 0.8 vol% TiO2 loadings owning to the well-formed conductive network and interfacial polarization effect of TiO2. The conductive Ni layer coating on the surface of glass fibers constructs an efficient conductive network due to its interfacial distribution between GF and PP. This interconnected Ni network provides fast electron transport channels to absorb the electromagnetic waves. Meanwhile, TiO2 dispersed among the network of NCGFs induces more interfacial polarization, and thus produces a synergistic effect to enhance the shielding effectiveness of composite. Such composite would be considered as a promising electromagnetic shielding material in aerospace and electronics.

Morphology and properties of polyphenylene sulfide (PPS)/polyvinylidene fluoride (PVDF) polymer alloys by melt blending

Polymer melt blending has become a main and important method to modify polymer materials for overcoming defects and obtaining excellent performance. The mechanical properties, compatibility, tribological properties and modification mechanisms of polyphenylene sulfide (PPS) alloys have been investigated over the last decades. However, there are few researches on PPS/polyvinylidene fluoride (PVDF) alloys, and material researchers have paid little attention to the manufacture and properties of PPS/PVDF alloys. In our research, the morphology, thermal properties and mechanical properties of PPS/PVDF alloys were first studied. PPS/PVDF alloys were prepared by a simple polymer melt blending. Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the morphology of PPS/PVDF alloys. It was found that the PPS/PVDF alloys had a “sea-island” structure with a poor adhesion at the interface between the PVDF phase and PPS matrix. The addition of PPS may also promote the transformation of α-phase to β-phase in PVDF. The thermal properties of PPS/PVDF alloys were confirmed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It indicated the addition of PVDF would accelerate the crystallization of PPS and increase the crystal perfection of PPS. It was clearly that the thermal stability of PPS/PVDF alloys could be improved by the addition of PVDF especially when the PVDF content is lower than 20 wt %. When the content of PVDF was only 5 wt %, the tensile strength and tensile modulus of PPS/PVDF alloys had a significant improvement compared with pure PPS. Furthermore, it was also found that the addition of PVDF could also increase breaking elongation rate in a small degree.

Nonisothermal crystallization kinetics of polyphenylene sulfide composites based on organic clay modified by benzimidazolium salt

Polyphenylene sulfide (PPS)/organic clay nanocomposites were prepared by simple melt blending. A synthesized benzimidazolium salt was used to modify the sodium montmorillonite in order to improve the compatibility with the PPS. The nonisothermal crystallization kinetics of PPS/organic clay composites were investigated by differerntial scanning calorimetry(DSC). It was observed that the crystallization peak temperature of PPS/organic clay composites was higher than pure PPS at various cooling rates. Several models such as the Ozawa and Mo equation were used to characterize the nonisothermal cooling crystallization kinetics of the PPS/organic clay composites. The results indicated that the Ozawa equation was not successful, while the Mo equation was successful to describe the nanoisothermal ctystallization kinetics of PPS/organic clay nanocomposites. The results also indicated that organic clay not only served as heterogeneous nucleating agents for PPS crystallization at lower content but also restricted the mobility and diffusion of PPS chains at higher content. These results were further supported by the crystallization activation energy of the samples determined by the Kissinger method.

The shape memory, and the mechanical and thermal properties of TPU/ABS/CNT: a ternary polymer composite

Polymer blend nanocomposites based on thermoplastic polyurethane (TPU) elastomer, acrylonitrile butadiene styrene (ABS) and multi-walled nanotubes (MWCNTs) were prepared via a simple melt blending process.

Proton-radiation resistance of poly(ethylene terephthalate)–nanodiamond–graphene nanoplatelet nanocomposites

Poly(ethylene terephthalate) nanocomposites reinforced with 1 wt% of nanodiamond terminated with carboxylic groups or nanodiamond and 0.3 wt% nanographene platelets were prepared by simple melt blending in a twin-screw extruder to create high-performance polymer nanocomposites for application in high radiation environments. A study of structural modifications introduced by high-energy, 3 MeV proton beam irradiation of poly(ethylene terephthalate) and its nanocomposites was conducted using attenuated total reflectance Fourier transform infrared and Raman spectroscopy, differential scanning calorimetry, and photoluminescence measurements. It was shown that the composite materials containing small concentrations of nanodiamonds or nanodiamonds plus nanographene platelets exhibit improved radiation resistance compared with neat poly(ethylene terephthalate) exposed to proton irradiation under the same irradiation conditions. The nanocomposites containing the combination of nanodiamonds and nanographene platelets exhibited the highest stability. Nanofillers, particularly nanographene platelets, stabilized the amorphous phase and increased the crystallinity of polymer matrix exposed to proton irradiation, preserving polymer conformation, molecular weight distribution, and overall thermal properties of irradiated nanocomposites.

Development of nanocomposite with epoxidized natural rubber and functionalized multiwalled carbon nanotubes for enhanced thermal conductivity and gas barrier property

Abstract Multiwalled pristine carbon nanotubes (mwCNTs) were treated with conventional mixed acid to functionalize outer surface of nanotubes with two unique chemical approaches using aminosilane solution and TiO 2 dispersion. Pristine and functionalized mwCNTs were dispersed subsequently in matrices of natural rubber (NR)–chlorobutyl rubber (CIIR) and epoxidized natural rubber (ENR)–CIIR to prepare nanocomposites by simple and eco-friendly melt blending method. The effect of surface treatment of mwCNTs, and epoxidation of NR on the composite properties was evaluated for thermal conductivity and gas barrier property. Nanocomposites prepared with surface functionalized mwCNTs and epoxidized NR were found to exhibit greater thermal conductivity and excellent gas barrier properties compared to pristine mwCNT reinforced CIIR–NR nanocomposites. A maximum thermal conductivity was observed for nanocomposite obtained from 20% ENR and 3% (by weight) mwCNTs functionalized with aminosilane. While a maximum gas barrier property was exhibited by nanocomposite with 20% ENR and 3% (by weight) mwCNTs treated with TiO 2 . Results indicate that the presence of epoxy moieties of ENR provided a stronger network formation between aminosilane treated mwCNT surface and rubber matrices to exhibit higher thermal conductivity and metal oxide particles adhered to TiO 2 treated mwCNTs found to impart maximum resistance in transfer of oxygen gaseous molecules nanocomposite.

Largely toughening biodegradable poly(lactic acid)/thermoplastic polyurethane blends by adding MDI

ABSTRACTThis work focuses on largely toughening poly(lactic acid)/thermoplastic polyurethane (PLA/TPU) blend with lower content (20 wt %) of TPU using appropriate contents of 4,4‐methylene diphenyl diisocyanate (MDI) via simple melt blending. Both scanning electron micrographs and differential scanning calorimetry curves suggest little change of the compatibility between the PLA and TPU phases by adding the MDI. Dynamic rheological test demonstrates that a reaction occurs between the TPU phase and MDI during melt blending. Combining the rheological behaviors and gel contents of the blends, it can be speculated that adding the MDI extends the TPU chains and forms branched and crosslinked structure in the TPU chains sequentially. Toughening mechanism is analyzed and different impact strengths for the blends with different MDI contents are explained based on combined effects of the decreased crystallinities for the PLA matrix and the extended, branched and crosslinked structure in the TPU chains. A 0.8 wt % MDI content is optimal in terms of the impact strength (100.6 kJ/m2) and the elongation at break (392.4%). The former is about 1.9 and 32.5 times of that for the blend without MDI and the PLA, respectively. Moreover, the MDI results in some increase in the tensile strength of the blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42511.

Modification of montmorillonite by different surfactants and its use for the preparation of polyphenylene sulfide nanocomposites

Polyphenylene sulfide (PPS)/clay composites were prepared by simple melt blending. Three different kinds of surfactants such as cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl benzene sulfonate (SDBS), and synthetic 1,3-dihexadecyl-3H-benzimidazolium bromide (Bz) were used as organic modifiers for the organic modification process. The benzimidazolium-modified montmorillonite (Bz-MMT) and CTAB-modified MMT (CTAB-MMT) exhibited larger interlayer spacing than SDBS-modified MMT (SDBS-MMT), while SDBS-MMT and Bz-MMT exhibited higher thermal stability compared with the CTAB-MMT. The morphology of the PPS/organic MMT nanocomposites was evaluated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The nanocomposites based on SDBS-MMT and Bz-MMT exhibited good overall dispersion of organic MMT with a mixed dispersion of intercalated and exfoliated structures. Differential scanning calorimetry and thermogravimetric analysis (TGA) were used to evaluate the thermal properties of PPS/organic MMT nanocomposites. The crystallization process of PPS in all nanocomposites was accelerated, and the crystallinity also increased, when compared with the pure PPS from the DSC analysis. The TGA analysis indicated that nanocomposites based on SDBS-MMT and Bz-MMT exhibited higher thermal stability than composites based on CTAB-MMT due to the well-dispersed nanoplatelets.

Improving dielectric properties and thermal conductivity of polymer composites withCaCu3Ti4O12and β-SiChybrid fillers

In this paper, we report a series of homogeneous polymeric composites with enhanced dielectric properties and thermal conductivity. The composites were constituted of polyvinylidene fluorides (PVDFs) matrix and CaCu3Ti4O12(CCTO) monolithic or CCTO/β- SiC hybrid fillers, and prepared by simple melt blending and hot moulding technique. The influence of different types of fillers and their composition on the dielectric response and thermal conductivity of the obtained composites was studied. Results show that hybrid loading is preferred and a reasonable combination of thermal conductivity (0.80 W⋅m-1⋅K-1), dielectric constant (∼50) and dielectric loss (∼0.07) at 103Hz was achieved in the PVDF composite containing 40 vol.% CCTO and 10 vol.% β- SiC . The strong dipolar and interfacial polarization derived from the fillers are responsible for the enhancement of the dielectric constant, while the formation of thermally conductive networks/chains by β- SiC whiskers contributes to the improved thermal conductivity.

Enhancing cold crystallization of poly(l-lactide) by a montmorillonitic substrate favoring nucleation

Abstract A montmorillonite (MMT) with nucleating surface (NMMT) supported by chemically calcium phenylphosphonic acid (PPCa), an effective nucleant for poly( l -lactide) (PLLA), was prepared through the chemical reaction between phenylphosphonic acid (PPOA) and calcium ion on the surface of MMT. Then, NMMT was introduced into PLLA via simple melt blending. The overall isothermal cold crystallization rates of PLLA were faster in the blends than in neat PLLA, indicative of the nucleating effect of the NMMT in the blends. The crystal structure of PLLA and its blends remained unchanged despite the addition of NMMT in the blends. For the nonisothermal cold crystallization, the crystallization process of PLLA was accelerated by increasing both heating rate and the NMMT contents. The Avrami equation and the combined Ozawa–Avrami model could describe it successfully. Moreover, the activation energy for nonisothermal cold crystallization of neat PLLA and its blends based on Friedman equation was estimated.