Mechanical Properties Of Polymer Blends Research Articles

Effect of mixing temperature on the dispersion and degradation behaviors of HDPE/UHMWPE blends

Abstract There is currently considerable interest in high-density polyethylene (HDPE)/ultra-high-molecular-weight polyethylene (UHMWPE) blends as recyclable all-polyolefin materials with favorable mechanical properties that can be processed by continuous melt-mixing. Optimal mixing is required to improve the mechanical properties of polymer blends by ensuring their dispersibility and low degradation. In the present study, we investigated the effects of mixing temperature on the dispersion and degradation behaviors of HDPE/UHMWPE blends. Neat HDPE and a HDPE blend comprising 5 % UHMWPE were obtained by melt-mixing while changing the input energy in an internal batch mixer under a nitrogen atmosphere. The temperature of the mixer was set at 200 °C for neat HDPE, and at 180, 200, and 220 °C for the HDPE/UHMWPE blends. Optical microscopy and thermal analysis revealed that the dispersion of UHMWPE in HDPE was accelerated at higher mixing temperatures. However, in the high input energy range, mixing at 200 °C resulted in the most favorable dispersion. Gel permeation chromatography and rheological measurements suggested that chain scission and branching/crosslinking due to degradation were accelerated at higher mixing temperatures, even when mixing in a nitrogen atmosphere. Chemiluminescence measurements suggested that chain scission and branching/crosslinking were caused by an initial oxidation reaction. Furthermore, for the same input energy, the maximum shear stress increased as the mixing temperature decreased, but the mixing time and thermal history increased as the mixing temperature increased. The results suggest that in a blend comprising HDPE and UHMWPE, mixing at the molecular level due to high temperature and fine dispersion of UHMWPE due to shear stress proceed simultaneously. On the other hand, the results also confirmed that degradation was more influenced by the promotion of oxidation due to high temperatures and prolonged mixing than by shear stress.

Bio-Based PLA/PBS/PBAT Ternary Blends with Added Nanohydroxyapatite: A Thermal, Physical, and Mechanical Study.

The physical and mechanical properties of novel bio-based polymer blends of polylactic acid (PLA), poly(butylene succinate) (PBS), and poly (butylene adipate-co-terephthalate) (PBAT) with various added amounts of nanohydroxyapatite (nHA) were investigated in this study. The formulations of PLA/PBS/PBAT/nHA blends were divided into two series, A and B, containing 70 or 80 wt% PLA, respectively. Samples of four specimens per series were prepared using a twin-screw extruder, and different amounts of nHA were added to meet the regeneration needs of bone graft materials. FTIR and XRD analyses were employed to identify the presence of each polymer and nHA in the various blends. The crystallization behavior of these blends was examined using DSC. Tensile and impact strength tests were performed on all samples to screen feasible formulations of polymer blends for bone graft material applications. Surface morphology analyses were conducted using SEM, and the dispersion of nHA particles in the blends was further tested using TEM. The added nHA also served as a nucleating agent aimed at improving the crystallinity and mechanical properties of the blends. Through the above analyses, the physical and mechanical properties of the polymer blends are reported and the most promising bone graft material formulations are suggested. All blends were tested for thermal degradation analysis using TGA and thermal stability was confirmed. The water absorption experiments carried out in this study showed that the addition of nHA could improve the hydrophilicity of the blends.

Effect of Mixing Conditions on Dispersion and Degradation Behavior of HDPE/UHMWPE Blends

High density polyethylene (HDPE) / ultra high molecular weight polyethylene (UHMWPE) blend is expected as an all-polyolefin recycle material that can achieve both mechanical properties and a continuous melt-mixing process. In order to improve the mechanical properties of polymer blends, optimal mixing is required to achieve both good dispersibility and low degradation. In this study, the effect of mixing conditions on the dispersion and degradation behavior of HDPE/UHMWPE blends were investigated. Neat HDPE and HDPE with 5% UHMWPE were obtained by melt mixing in internal batch mixer. Time of mixing, Specific Energy Input (SEI), and rotation speed of the rotors were changed. From the results of microscopic observation and a differential scanning calorimetry (DSC), the dispersibility progressed with the increase in SEI regardless of the rotor speed. The results of Gel Permeation Chromatography (GPC) show the molecular chain scission was also promoted by the increase in SEI. In the other hands, the results of oscillatory shear test show the increase in storage modulus G’ were promoted by increase in not only SEI but rotor speed. Furthermore, the molecular chain scission and increase in G’ were significantly suppressed by the nitrogen atmosphere.

Preparation and Study of Mechanical properties of Polymer Blends from Recycled Materials Polymethylmethacryalate with Different Ratios of polyester and Shilajit

Preparation and Study of Mechanical properties of Polymer Blends from Recycled Materials Polymethylmethacryalate with Different Ratios of polyester and Shilajit

Comparative experimental and modelling study of the thermal and thermo-mechanical properties of LLDPE/wax blends

The interactions and morphology of molecules in a polymer blend influence the physical properties of the blend. However, little is known about the influence of molecular interaction and morphology on the thermal and mechanical properties of LLDPE/wax blends. Although cooling rate can be used to investigate blends' thermal and mechanical properties, it is inadequate to determine interactions between the molecules in the LLDPE/wax blends. However, since the morphology is related to the thermal and mechanical properties of polymer blends and could be related to the cooling rate, LLDPE/wax samples prepared by melt mixing were cooled at different rates. The thermal and mechanical properties of the LLDPE/wax blends were modelled through molecular dynamic simulations. The modelled transitions were compared to experimentally determined mechanical relaxations of LLDPE/wax blends to investigate the effect of wax addition on the blend crystallinity. The crystallization behaviour of the blends was studied by differential scanning calorimetry, dynamic mechanical behaviour by dynamic mechanical analysis, and differences in crystallinity by X-ray diffraction. There were no significant differences between the results for the slow- and quench-cooled samples, confirming the rapid crystallization of both the LLDPE and the wax. Experiments and molecular dynamics simulations confirmed the cocrystallization of wax with LLDPE.

Recycling of Pretreated Polyolefin-Based Ocean-Bound Plastic Waste by Incorporating Clay and Rubber

Plastic waste found in oceans has become a major concern because of its impact on marine organisms and human health. There is significant global interest in recycling these materials, but their reclamation, sorting, cleaning, and reprocessing, along with the degradation that occurs in the natural environment, all make it difficult to achieve high quality recycled resins from ocean plastic waste. To mitigate these limitations, various additives including clay and rubber were explored. In this study, we compounded different types of ocean-bound (o-HDPE and o-PP) and virgin polymers (v-LDPE and v-PS) with various additives including a functionalized clay, styrene-multi-block-copolymer (SMB), and ethylene-propylene-based rubber (EPR). Physical observation showed that all blends containing PS were brittle due to the weak interfaces between the polyolefin regions and the PS domains within the polymer blend matrix. Blends containing clay showed rough surfaces and brittleness because of the non-uniform distribution of clay particles in the polymer matrix. To evaluate the properties and compatibility of the blends, characterizations using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and small-amplitude oscillatory shear (SAOS) rheology were carried out. The polymer blend (v-LDPE, o-HDPE, o-PP) containing EPR showed improved elasticity. Incorporating additives such as rubber could improve the mechanical properties of polymer blends for recycling purposes.

Novel Structure to Improve Mechanical Properties of Polymer Blends: Multilayered Ribbons

Ribbon-like dispersed phase in polymer blends can provide excellent mechanical properties for the matrix, compared with the fibrillar or spherical dispersed phase. However, it is difficult to contr...

Effect of Multi-Level Microstructure on Local and Bulk Mechanical Properties in Micro-Injection Molded PC/PET Blend

This study introduces a method to investigate the relationship between the multi-level microstructures and mechanical properties of polymer blends prepared by micro-injection molding (µIM). Special morphological features were systematically researched. Polycarbonate (PC), poly(ethylene terephthalate) (PET), and PC/PET microparts all exhibit typical “skin-core” morphologies. The thickness of the core layer is much greater than that of the skin layer, and the thickness of the skin layer gradually decreases along the flow direction. Photoacoustic Fourier transform infrared spectroscopy records reveal that the PC molecular chain has the biggest orientation degree, followed by PC/PET and PET chains under the same µIM processing conditions. Moreover, the molecular chains orientation in the skin layer is more than 50% that in the core layer. Nanoindentation tests are conducted to study local mechanical properties. The higher modulus in the shear layer is affected to a greater extent by high shear action in comparison with the frozen and core layers. Uniaxial tensile testing demonstrates that the tensile strength of PC/PET micropart is 15.5% higher than that of the PET micropart, while the toughness is 16% higher than that of the PC microparts. In-situ, high- speed tensile imaging, combined with scanning electron microscopy micrographs of the fracture section, are used to study the fracture behaviors of the microparts. The results gathered in this paper may provide a theoretical basis and data to support the feasibility and efficiency of micro-injection molded polymer blends.

Correlative analysis between solid-state NMR and morphology for blends of poly(lactic acid) and poly(butylene adipate-co-butylene terephthalate)

Morphological changes in polymer blending process were investigated using integrated analyses by solid-state NMR and magnetic relaxation. The study examined previous reported mechanical properties of polymer blends incorporating poly(lactic acid) (PLA) and poly(butylene adipate-co-butylene terephthalate) (PBAT) over a range of compositions, along with a crosslinking reagent. The X-ray diffraction (XRD) and the differential scanning calorimeter (DSC) results showed that the crystallinity of PLA decreased with increasing the PBAT content. According to the integrated analysis data and imaging by micro-focus X-ray computed tomography (CT), polymer tensile properties were dominated by interfacial affinity between the molecular mobilities of PLA and PBAT; depending on the blending ratio, the polymer morphology changed from a discontinuous “sea-island” form to a bicontinuous morphology. Addition of a crosslinking reagent was observed via X-ray CT to homogenize the PLA and PBAT blend at the micron length scale, even though both polymers were still heterogeneous at the nanoscale as elucidated by NMR analysis. As well as the morphological change in micro scale, the molecular mobility changes of the total polymer blend system, which could be evaluated by the integrated solid-state NMR analyses, brought about greater elongation at the break point in dynamic tensile testing.

Study of the effect of electron beam on thermal and mechanical properties of poly(lactic acid)/poly(butylene succinate) blends

In this research, the effect of radiation dose on thermal and mechanical properties of polymer blends between poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) were determined at the PLA/PBS weight ratios of 100/0, 80/20, and 0/100. Dicumyl peroxide (DCP) was used as additive at 0.2 phr. The radiation doses were varied at 0-150 kGy. There were some changes of chemical structure upon irradiation as observed via Fourier Transform Infrared Spectrometer (FT-IR), leading to the decrease of melting temperature (Tm) with the increase of radiation doses. Moreover, the flexural strength determined via Universal Testing Machine (UTM) were decreased with increasing radiation doses. The lowest biodegradation was found at the radiation dose of 50 kGy.

Effects of Irradiation by UV- Acceleration on Mechanical Properties of Polymer Blends (Polyester: Starch)

This work covers mixing of unsaturated polyester (un- polyester) with starch powders as polymer blends and study the effects of irradiation by UV-acceleration on mechanical properties of its. The unsaturated polyester was mixing by starch powders at particle size less than (45 µm) at selected weight fraction of (0, 0.5, 1, 1.5, 2, 2.5 and 3%). These properties involve ultimate tensile strength, modulus of elasticity, elongation percentage, flexural modulus, flexural strength, fracture toughness, impact strength and hardness. The results illustrate decrease in the ultimate tensile strength at and elongation percentage, while increasing modulus of elasticity, with increasing the weight ratio of starch powder to 3 % weight fraction, whereas the maximum value of hardness and flexural, impact properties happened at 1 % weight fraction for types of polymer blends.

Synergistic effects of Janus particles and triblock terpolymers on toughness of immiscible polymer blends

By influencing both the interfacial adhesion and the morphology, compatibilizers determine the mechanical properties of polymer blends. Here, we study the mechanical properties, in particular the fatigue crack propagation (FCP) of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN), compatibilized with Janus nanoparticles (JPs) and linear polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) triblock terpolymers. Synergistic effects of a mixture of both compatibilizers improve the FCP behavior and reveal the important role of interface stiffness and flexibility on the mechanical properties of polymer blends. The triblock terpolymer and JPs allow at the same time an elastic and stiff linkage at the blend interface and induce multiple deformation mechanisms such as crack bridging and matrix fibrillation that can dissipate energy and contribute to an improved FCP behavior. The presented concept allows tailoring macro-mechanical properties of immiscible polymer blends by adjusting blend morphology and interfacial properties.

Effect of Cationic Polypropylene on the Compatibility of Polypropylene/Poly(vinyl chloride) Blends

Graft copolymers were usually introduced to improve the compatibility and mechanical properties of polymer blends. In this paper, the effect of cationic vinyl monomer grafted polypropylene (FPP) with different grafting yields (GY) on mechanical properties of polypropylene (PP)/poly(vinyl chloride) (PVC) blends had been investigated. The results indicated that FPP could enhance compatibility of PP/PVC blend remarkably. The tensile strength and the impact strength of PP/PVC blends with a concentration of FPP (GY=16.78%) at 4 phr increased up to18.10% and 74.67%, respectively. The viscosity of PP/PVC/FPP blends had been also investigated, and the results showed PP/PVC/FPP (80/20/4) blend was higher than that of other PP/PVC/FPP when FPP (GY=16.78%) was added. The SEM micrographs suggested that the compatibility of the PP/PVC blend was optimum when FPP (GY=16.78%) was added.

Investigating Miscibility of Polymers and Its Impact on the Morphology, Thermal, and Mechanical Properties of Polymer Blends

The miscibility of polystyrene (PS)/poly(styrene-co-acrylonitrile) (PSAN) blend films, prepared by the solution casting technique using tetrahydrofuran as a common solvent, was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetry, Fourier transform infrared (FTIR) spectroscopy, and tensile testing. Morphological observations revealed partial miscibility of the blend. FTIR measurements also ascertained partial miscibility of the blend as slight variations in the spectra for various blend compositions were observed. DSC studies also confirmed the semicompatible nature of the examined blend by displaying a single \(T_{\mathrm{g}}\) for the composition, 25/75, and two \(T_{\mathrm{g}}\)’s for compositions, 50/50 and 75/25. The enhancement in thermal stability and mechanical properties which were quite pronounced for the composition, 25/75, also favored partial miscibility of the blend. The partial miscibility of the PS/PSAN blend may be attributed to the intramolecular repulsive effect, characteristic of a homopolymer/copolymer blend system, and the Pi–Pi stacking of phenyl rings of the blend components due to some structural similarities.

Morphology and Mechanical Properties of Polyoxymethylene and Acrylonitrile-Butadiene-Styrene Blends with Compatibilizer

The effects of polypropylene-graft-maleic anhydride (PP-g-MA) compatibilizers on the morphology and mechanical properties of polyoxymethylene (POM)/acrylonitrile-butadiene-styrene (ABS) blends were investigated. Two types of compatibilizers, PP-g-MA with maleic anhydride 0.50 wt% (PP-g-MA1) and PP-g-MA with maleic anhydride 1.31 wt% (PP-g-MA2) were used to study the interfacial adhesion of POM and ABS. POM/ABS blends with and without PP-g-MA compatibilizer were prepared by an internal mixer and molded by compression molding. Scanning electron microscope (SEM) was used to investigate the morphology of ABS phase in POM matrix. The results found that POM/ABS blends clearly demonstrated a two phase separation of dispersed ABS phase and the POM matrix phase, and ABS phase dispersed as spherical domains in POM matrix in a range of ABS 10-30 wt% and the blends containing ABS more than 30 wt% showed the elongated structure of ABS phase. The addition of PP-g-MA could improve the interfacial adhesion of POM/ABS blends due to the domain size of ABS phase decreased after adding PP-g-MA. The mechanical properties showed that the impact strength of POM/ABS blends decreased in a range of 10-20 wt% and did not change after 20 wt%. The addition of PP-g-MA did not change the impact strength of POM/ABS blends. The Young’s modulus of POM/ABS blends increased up to 30 wt% of ABS and then decreased. While the blends showed the decrease of tensile strength and percent strain at break with increasing ABS content. The addition of PP-g-MA increased the tensile strength of POM/ABS blends in a range of 30-40 wt% of ABS. The above results indicated that the morphology had an effect on the mechanical properties of polymer blends.

Controlling morphology, electrical, and mechanical properties of polymer blends by heterogeneous distribution of carbon nanotubes

Electrical and mechanical properties of some new composites made of copolyamide/polypropylene/carbon nanotubes (CPA/PP/CNTs) in different ratios, in correlation with their morphology, were investigated. The polymer blends based on polypropylene and low melting point copolyamide filled with CNTs were prepared by two methods. In the first procedure, CNTs were orderly distributed into the heterogeneous polymer matrix where filler occupied only one polymer component creating a highly branched conductive phase that provides a low value of the percolation threshold. In second case, CNTs were randomly distributed in the heterogeneous polymer matrix created by the blend CPA/PP yielding in a higher value of percolation threshold. Four factors influence on the distribution of filler, namely: thermodynamics, kinetics, chemical factor, and processing. Both electrical and mechanical properties are defined by spatial distribution of the conductive nanofiller in the polymer blend. POLYM. COMPOS., 37:2467–2477, 2016. © 2015 Society of Plastics Engineers

Sequential Mesoscale Approach for Determining the Effects of the Addition of a Block Copolymer Compatibilizer on the Mechanical Properties of Polymer Blends

The compatibilizing effects of the addition of a block copolymer on the mechanical properties of immiscible polymer blends were studied using a combined simulation method; this method used Meso Dyn to determine the morphology and a probabilistic lattice spring model(LSM) to determine the mechanical properties.The mechanical properties, including the Young's modulus, tensile strength, and fracture position, were analyzed as a function of the concentration of the additive. The simulation results showed that the polymer blends without any compatibilizer had poor mechanical properties, compared with the original components, primarily because of the lack of stress transfer across the sharp interface. The tensile strength increased dramatically with the addition of the compatibilizer. The fracture position moved from the interface further into the matrix with increases in the volume fraction of the compatibilizer, leading to the enhancement of the tensile strength. The Young's modulus varied slightly with increases in the concentration of the additive. These studies provide an efficient path for the correlation of the complex morphologies of polymer blends with their mechanical response.

Mechanical Properties of Poly(lactic acid) / Thermoplastic Starch Blends Crosslinked by Gamma Radiation

This research aims to determine the influences of radiation-induced crosslinking on the mechanical properties of polymer blends between poly (lactic acid) (PLA) and thermoplastic starch (TPS). PLA and TPS were mixed at different ratios (90:10, 80:20, 70:30, 60:40) in the presence of a crosslinking agent using a twin screw extruder. The blends were compression molded into films. The film samples were irradiated by gamma radiation at different doses. Gel fraction was used to determine crosslinking efficiency. Results showed that gamma radiation was able to induce crosslinking for PLA/TPS blends. The gel fraction and mechanical properties decreased with increasing TPS content. The optimum ratio of PLA:TPS with the maximum gel fraction and mechanical properties was 90:10 and the optimum dose was 40 kGy by gamma radiation.

Effect of Additive on Crystallization and Mechanical Properties of Polymer Blends of Poly(Lactic Acid) and Poly[(Butylene Succinate)-co-Adipate

The effect of additive on crystallization and mechanical properties of poly(lactic acid) (PLA) and poly(butylene succinate-co-adipate) (PBSA) blend was studied. PLA and PBSA were blended in a twin screw extruder, which incorporated poly(butylene adipate-co-terephthalate) (PBAT) as an additive in PLA/PBSA blend. The ratio of PLA/PBSA was 80/20. The contents of PBAT were varied from 0 to 50 wt%. The thermal properties and crystallization behavior of PLA/PBSA/PBAT blends were analyzed by differential scanning calorimetry. The effect of PBAT contents on non-isothermal crystallization kinetic of the composites was investigated by using Avrami equation. Tensile strength and impact performance of the PLA/PBSA/PBAT blends decreased when increasing PBAT contents. It can be noted that the addition of 20 wt% PBAT showed the maximum impact performance of the PLA/PBSA blends.

The Effect of Thermal Pretreatments on the Mechanical Properties of the Blend Consisting of Poly(Ethyl Methacrylate) and Poly(Ethylene Oxide)

The solution cast technique for the preparation of polymer blends of poly(ethylmethacrylate) (PEMA) and poly(ethylene oxide)(PEO) is described. Polymer blends of poly(ethylmethacrylate) (PEMA) and poly(ethylene oxide) (PEO) with different weight percentage ratio of the two polymers have been prepared. Effect of thermal pretreatments like annealing and quenching on the mechanical properties of polymer blends of PEMA and PEO have been reported using Vicker's microhardness testing. The thermal pretreatment produces morphological changes in the blend system investigated. These thermal pretreatments results in hardening and softening of blend systems under investigation.