Thermoplastic Blends Research Articles

A study of reusability assessment and thermal behaviors for thermoplastic composite materials after melting process: Polypropylene/ thermoplastic polyurethane blends

In recent years, the excess amount of disposable plastic wastes has gained a concern for the environment. Polypropylene (PP) and thermoplastic polyurethane (TTPU) are both materials that can be properly heated to reform and reuse due to the inherent characteristics of thermoplastic materials. However, the using efficacy may be compromised as the waste may be overheating and thus damaged during the reheating process. Additionally, PP and TTPU are incompatible and immiscible, for which a compatibilizer - polypropylene grafted maleic anhydride (MA) was used. Hence, this study goals to investigate the synergistic effect between these materials and also discuss the compatibilized effect caused by MA. The thermal degradation behavior, melting and crystallization behaviors, and surface morphology of PP/MA/TTPU blends are evaluated under appropriate considerations. In light of the thermal degradation, the presence of thermally stable PP improves the thermal stability of TTPU accordingly. From TGA and DTG results, the addition of MA is also helpful, and therefore the third thermal degradation temperature (T3max) is increased by 5 °C averagely when compare to neat PP. T1max and T3max of PP/MA/TTPU are postponed about 2 and 4 °C when TTPU content varied from 10 to 30 wt%. SEM images show that the employment of TTPU strengthens the toughness of the surface, and with the aid of 5 wt% MA, PP and TTPU exhibit greater interfacial compatibility and better adhesion. Above all, this study aims to investigate the feasibility of using thermoplastic based on the consideration of how to sustain the excess plastic products and develop the measure to melt-blend diverse thermoplastics for reclamation. The excessive plastics via an easy and convenient melt extrusion process is expected to be regarded as an eco-friendly method for green development on mother earth.

Assessing thermomechanical properties of a reactive maleic anhydride grafted styrene‐ethylene‐butylene‐styrene/thermoplastic polyurethane blend with temperature scanning stress relaxation method

AbstractThe phenomenon of stress relaxation in thermoplastic elastomers (TPEs) is common and influences the end‐use properties of polymers. Temperature scanning stress relaxation (TSSR) method extends an advanced method to study the stress relaxation of TPEs at elevated temperatures. A reactive blend system based on maleic anhydride grafted styrene‐ethylene‐butylene‐styrene and thermoplastic polyurethane is explored for its relaxation behavior at temperature up to 200°C with TSSR meter. The relaxation spectrum revealed the transitions occurring in the blends as well as the extent of interfacial interaction present. Direct measurement of elasticity of the blends was obtained from the TSSR index (RI). Glass transition temperature of the samples was measured from dynamic mechanical analysis. The elastic nature of the blends was also pursued from the storage modulus values and results were in line with TSSR results. The density of crosslinks in the system was assessed with both TSSR and the conventional Flory‐Rehner equation and a similar trend was obtained. Atomic force microscopy and scanning electron microscopy revealed the dispersed morphology of the blends.

Simultaneously improved electromagnetic interference shielding and flame retarding properties of poly (butylene succinate)/thermoplastic polyurethane blends by constructing segregated flame retardants and multi-walled carbon nanotubes double network

Simultaneous improvement on the electromagnetic interference (EMI) shielding and flame retardancy of polymer composites is dependent on the controllable distribution of functional fillers. Herein, a facile method to control distribution of multi-walled carbon nanotubes (MWCNTs) and flame retardants in poly (butylene succinate)/thermoplastic polyurethane blends by constructing segregated structure was reported. High-efficiently conductive networks could be easily constructed in segregated structure, resulting in a low percolation threshold of 0.22 wt%. High EMI shielding effectiveness of ~45 dB could be achieved in segregated samples with 2.5 wt% MWCNTs which far exceeds commercial requirement. Furthermore, the segregated samples also exhibited excellent flame retardancy and the UL-94 rating reached V-0 with prompt self-extinguishment and disappeared melt-dripping. More importantly, this unique network could provide synergistic enhancement for the flame retardancy which increases with the increasing of MWCNTs loading. Accordingly, this work provided a promising route to fabricate various high-performance EMI shielding polymer composites with excellent flame retardancy.

Interfacial Polarization in Thermoplastic Basalt Fiber-Reinforced Composites.

The aim of this work was to study the interfacial behavior of basalt-fiber-reinforced thermoplastic blends of polypropylene and poly(butylene terephthalate) (PP/PBT). We examined the effect of two compatibilizers and two basalt fiber (BF) sizings: commercial (REF) and experimental (EXP). Differential scanning calorimetry was used to assess the influence of BFs on the phase structure of obtained composites. Furthermore, dielectric relaxation spectroscopy was used for the first time to non-destructively study the interfacial adhesion within an entire volume of BF-reinforced composites by assessing the α relaxation, DC conductivity, and Maxwell–Wagner–Sillars (MWS) polarization. The fiber–matrix adhesion was further investigated using the Havriliak–Negami model. Using complex plane analysis, the dielectric strength, which is inversely related to the adhesion, was calculated. The composites reinforced with EXP fibers showed significantly lower values of dielectric strength compared to the REF fibers, indicating better adhesion between the reinforcement and blend matrix. Static bending tests also confirmed improved fiber adhesion with EXP fibers, while also suggesting a synergistic effect between compatibilizer and sizing in enhancing interfacial properties. Thus, we conclude that substantially improved adhesion of PP/PBT BF-reinforced composites is the result of mutual interactions of functional groups of blend matrix, mostly from blend compatibilizer, and fiber surface due to sizing.

Liquefaction of corn husks and properties of biodegradable biopolyol blends

AbstractBACKGROUNDA valorization route of corn husks from agrarian practices was performed by liquefaction using glycerol as liquefaction solvent to obtain biopolyols used as bioadditives in starch blends with the aim to find a useful industrial application in polymer processing.RESULTSLow‐molecular‐weight liquefied products obtained from a practically total conversion reaction can be used for composite formulations (OH number, 310 mg KOH g−1; viscosity, 3.4 Pa s; molecular weight, 549 g mol−1). Concurrently, starch thermoplastic blends using various proportions of biopolyol (40, 30 and 20 wt%) as plasticizer were produced with maximum torque and plasticization energy ranging from 3.4 to 15.1 Nm and from 1.7 to 9.1 Nm min−1. The starch/biopolyol (70/30) sheets obtained by thermopressing showed properties similar to those of controls (starch/glycerol: 70/30), such as sensitivity to environment, retrodegradation, biodegradability and density; however, mechanical properties exhibited better performance compared to controls (Young’s modulus, 14 MPa; strain at break, 33%; tensile strength, 1.2 MPa), which indicates a material with major mechanical balance.CONCLUSIONSThe adequacy in the conversion of corn husks into biopolyols that could be used as improved biobased plasticizers to obtain biodegradable blends is revealed. Hence, this study demonstrates that liquefied corn husk residues are sustainable resources with suitable properties for polymer processing, which can be applied in bioplastics and be considered as a value‐added feature. © 2020 Society of Chemical Industry

Preparation, characterization, and permeability of novel poly (lactic acid)-based blends filled with thymol and ZnO

Novel thin sheets based on poly (lactic acid)/poly (caprolactone)/thermoplastic starch ternary blends were fabricated by incorporating thymol, zinc oxide nanoparticles (ZnO-NPs) and thymol/ZnO-NPs at different concentrations (6, 9, 12 wt% thymol and 1, 3, 5 wt% ZnO). The gas/water vapor barrier properties of the nanocomposites comprising the effects of polar and non-polar molecules and their leading mechanisms were thoroughly discussed. Moreover, the localization preference of ZnO-NPs, morphology along with mechanical, and thermal properties of the nanocomposites were investigated. A significant improvement of 58% in the water vapor impermeability by 5 wt% ZnO and 12 wt% thymol loading was achieved. Finally, the fitting of the Maxwell model on the experimental data revealed that this model cannot correctly predict the permeation behavior of ZnO-filled nanocomposites. Results suggested that these nanocomposites could be capable of being used as the packaging materials with high barrier performance.

Exploring the role of lignin structure in molecular dynamics of lignin/bio-derived thermoplastic elastomer polyurethane blends

The relaxation behavior of two lignins (Alcell organosolv, OSL, and hydroxypropyl modified Kraft, ML) and bio-based thermoplastic polyurethane (TPU) blends have been studied by Differential scanning calorimetry (DSC), Dynamic-mechanical analysis (DMA) and Dielectric relaxation spectroscopy (DRS). The effect of blending on the glass and local relaxation processes as a function of composition, frequency, and temperature has been assessed. The dielectric spectra were resolved into dipolar relaxations as well as conductive processes for differing blend compositions. Characteristic relaxation times, activation energies and dielectric relaxation strengths of lignin/xTPU blends were also investigated. It was found that blending suppresses the α-relaxation process of the blends compared to virgin TPU. On the other hand, while the position of the β-relaxation was not influenced by blending, a reduction of the activation energies, Ea, of this process was observed in the lignin/xTPU blends. Finally, changes are observed in the conductivity behavior of both blends, with conductivity processes more favorable for the OSL/xTPU blends.

Thermoplastic Elastomeric Composites Filled with Lignocellulose Bioadditives. Part 1: Morphology, Processing, Thermal and Rheological Properties.

Thermoplastic elastomer blends based on natural rubber (NR) and ethylene-vinyl acetate copolymer (EVA) with different weight ratios (30, 40, 50, 60 and 70 parts per hundred rubber (phr) of NR) and 10, 20 and 30 phr of straw were prepared and characterized. Current environmental problems were the motivation to produce this type of system, namely: the need to replace plastics at least partly with natural materials; increasing the amount of renewable raw materials and managing excess straw production. When using this bioadditive in traditional materials, the high processing temperature can be problematic, leading to the degradation of straw fibers. The solution can be polymer mixtures that are prepared at significantly lower temperatures. Scanning electron microscope (SEM) imaging was used to investigate the particle size of fibers and phase morphology of composites. Moreover, determination of the thermal properties of the filler and composites showed that the processing temperature used in the production of NR/EVA blends reduces the risk of degradation of the natural filler. Differential scanning calorimetry (DSC) was used to determine the thermal behavior of the filled composites. Finally, rheological tests of materials allow the determination of optimal processing parameters and properties of materials in dynamic conditions. The proposed blends exhibit elastic properties, and due to the lack of chemical cross-linking they can be processed and recycled like thermoplastics. In addition, they offset the disadvantages and combine the advantages of natural rubber and ethylene-vinyl acetate copolymer in the form of thermoplastic elastomeric biocomposites.

Mechanical and rheological testing to develop thermoplastic elastomer-polyborodimethylsiloxane blends for personal impact protection

To claim ‘wearability’, clothing for protection against impact injury must not only act locally as a rigid shell under impact in order to satisfy drop-weight tests, but also flex freely with normal movement and offer permeability and light weight. Previous materials used carrier textiles coated with ‘dilatant’ but mechanically weak polyborodimethylsiloxane (PBDMS) compounds. We outline a procedure for developing blends of PBDMS with thermoplastic elastomers which, while minimizing the force transmitted in standard drop-weight tests on monolithic plate, can also be injection moulded into more wearable 3D shell structures. The first successful blends were developed by trial-and-error, involving the melding and testing of many plate specimens. The new procedure uses dynamic mechanical thermal analysis and time-temperature superposition to calibrate Zener-solid models for specific conditions within the service temperature and impact-speed envelope. Each model material is then subjected to a virtual drop-weight impact test to estimate the peak transmitted impact force. These results guide the selection of blends suitable for further development, correlating well with those obtained using the previous, more laborious procedure. When distributed within a suitable blend, PBDMS contributes considerably greater impact force attenuation than bulk uniaxial tests indicate.

Automotive applications of thermoplastic vulcanizates

AbstractThermoplastic vulcanizates (TPVs) are special classes of thermoplastic elastomers, in which dynamic vulcanization of the rubber phase takes place during melt mixing with a semicrystalline thermoplastic matrix phase at elevated temperature. This review article focus on the different types of thermoplastic vulcanizates (TPVs) from various elastomer and thermoplastic blends that are suitable for the automotive applications purpose. A detailed study of the various TPVs based on polypropylene‐ethylene propylene diene rubber (PP‐EPDM) and polypropylene‐ethylene α‐olefin has been focused and their application in the automobile sector has been summarized. Most of the commercially available TPVs are PP‐EPDM based. Limited applications of that TPVs in high heat and oil resistant application purposes requires new generation of TPVs. High performance TPVs or super TPVs are new generation TPVs that exhibit high heat resistance as well as excellent oil resistance property suitable for automotive under‐the‐hood applications. Therefore TPVs based on XNBR‐PA12, HNBR‐PA12 and FKM‐PA6 system has also been explored in details in this study and the possibility of the use of those TPV system has been focused for the high temperature application purpose in the automobile sector where high and oil resistant application properties is the prime concern.

Aligning α‐alumina platelets via uniaxial pressing of ceramic‐filled polymer blends for improved sintered transparency

AbstractUniaxial warm pressing was used to align alumina platelet‐filled polyethylene‐based copolymer blends. The solids loading (30‐40 vol.%) and platelet diameter (1.2 and 11 μm) were varied to compare effects on viscosity, percent reduction, and final alignment. All ceramic‐filled thermoplastic polymer blends exhibited pseudoplastic behavior. Crystallographic alignment of green body samples was quantified by the orientation parameter (r) and grain misalignment angle (full width at half maximum, FWHM) obtained from rocking curve analysis. Blends with 11 μm diameter platelets displayed a higher temperature sensitivity constant, better flow properties, and higher alignment compared to blends with 1.2 μm diameter platelets. Optimal samples produced with blends containing 30 vol.% of 11 μm diameter platelets demonstrated an alignment of r = .251 ± .017; FWHM = 11.16° ± 1.16°. A sample with optimal alignment was hot‐pressed to transparency and obtained an in‐line transmission of 70.0% at 645 nm. The final alignment of this pre‐aligned hot‐pressed sample (r = .254 ± .008; FWHM = 11.38° ± 0.54°) improved when compared to a non‐pre‐aligned sample (r = .283 ± .005; FWHM = 13.40° ± 0.38°).

Polyvinylidene Fluoride/Hydrogenated Nitrile Rubber-Based Flexible Electroactive Polymer Blend and Its Nanocomposites with Improved Actuated Strain: Characterization and Analysis of Electrostrictive Behavior

A polyvinylidene fluoride (PVDF)/hydrogenated nitrile rubber (HNBR)-based flexible electroactive polymer blend was developed by generating a suitable morphology that showed a judicious combination of strength and flexibility. The blend, containing 30:70 wt/wt ratio of PVDF/HNBR, was thermoplastic elastomeric in nature and exhibited visible planar actuation in the presence of an electric field. To the best of our knowledge, the electromechanical actuation of the thermoplastic elastomeric blend has been reported for the first time. The maximum planar strain was 5%, and the actuation was triggered by the strong induced polarization in both PVDF and HNBR phases that gave rise to a high dielectric constant and low dielectric losses. The interphase between PVDF and HNBR was also very strong, which made the thermoplastic elastomer (TPE) susceptible to withstand high electric field. The TPE also exhibited a bending actuation of 0.6 mm at a low electric field of 20 kV/mm, promising enough to be used in microdevices. Addition of barium titanate (BT) nanoparticles increased the dielectric constant as they were homogeneously distributed in both the phases. The maximum planar actuation (∼10%) was observed at 10 wt % BT loading, whereas 5 wt % loading exhibited the maximum dielectric strength (∼120 kV/mm). At 5 wt % loading, the bending actuation was 0.9 mm at 20 kV/mm, which was 50% higher than that of unfilled TPE. Both the TPE and its nanocomposite also showed good history dependency in a cyclic electric field. In summary, the study provides an attractive and unexplored alternative of developing electromechanically active TPEs and their nanocomposites.

New low loss soft thermoplastic blends for microwave applications

All organic soft dielectrics are growing more and more interest in the electronic industry owing to their light weight, low cost and the flexibility they yield compared to the rigid devices. In the specific field of microwave communicating devices planar printed (patch) antennas on a soft dielectric substrate are sought for their conformability and advantageous compactness. In this article, two soft thermoplastic elastomer blends based on polypropylene (PP) or low-density polyethylene (LDPE) were tested. The fabrication process and the established characterization steps have been fully presented. More specifically, in order to characterize the dielectric film up to 40 GHz, the microstrip ring resonator with coplanar waveguide access has been adapted to a new configuration specimen sample. The results of the characterizations obtained showed very encouraging performances for microwave applications. Indeed, the measured dielectric constant and loss tangent up to 40 GHz were found to be and for both blends. The fabrication and the radiation characteristics of a patch antenna on a new performing PP or LDPE-based elastomer blends as the soft dielectric substrate was demonstrated and analysed. The proof of the concept of the investigated device consists of a microstrip patch antenna with an operation frequency of about 10 GHz. These dielectric features render the polyolefin based blends very promising as a soft material for microwave engineering, which is confirmed by the measured antenna properties: the gain, the directivity as well as the efficiency have been calculated from the measured radiation pattern and were recorded as 4.6 dB, 7.7 dB and 46% respectively for the r-PP based blend and 4.8 dB, 8.1 dB and 51% for the LDPE based blend.

Thermoplastic elastomer blend based on EMA and NBR; optimization of process parameters

ABSTRACTEMA–NBR has been explored to be a potential thermoplastic elastomer blend having good thermal stability as well as oil resistance property. The present investigation reports the optimization of process parameters for the novel polymer blends based on poly(ethylene‐co‐methyl acrylate) (EMA) and poly(acrylonitrile‐co‐butadiene) rubber (NBR) with criteria based on the statistical design of experiment (Taguchi L9 orthogonal array). In this case, the polymer blends were prepared by changing the polymer blending conditions such as mixing temperature, mixing time and rotor speed as per Taguchi's L9 orthogonal array. Optimization of the process parameters was carried out based on the physicomechanical properties such as tensile strength, elongation at break, hardness, and tensile impact strength of the resulting EMA/NBR blend. Each processing parameter has been optimized from the experimental data, which are converted into signal‐to‐noise ratio. The standard statistical technique of analysis of variance result was used to evaluate the proportional role of the different control variables. It has been found that the mixing temperature play very significant role trailed by rotor speed and mixing time in controlling droplet matrix morphology of the EMA/NBR blends. Predominantly, these factors affect the size of the NBR domain and its distribution in the EMA matrix, which in turn have a notable contribution to the physicomechanical properties of the blends. By the optimization of processing conditions, the NBR matrix domain size greatly decreases, leading to significant improvement in physicomechanical properties of the EMA/NBR blends. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48900.

Fungal degradation of reprocessed PP/PBAT/thermoplastic starch blends

It is well known that the inadequate disposal of polymeric materials causes significant environmental problems. Recycling and the use of biodegradable polymers are among the methods used to minimize these problems. However, the low mechanical performance of the majority of biodegradable polymers hinders the direct substitution of synthetic polymers, such as polyethylene (PE), polypropylene (PP) and polystyrene (PS), by biodegradable ones. Blending synthetic and biodegradable polymers is a way to develop recyclable biodegradable products with a good set of mechanical properties. Therefore, in this work we investigate the influence of extrusion cycles on the degradation of a polypropylene/poly (butylene adipate-co-terephthalate)/thermoplastic starch blend before and after inoculation with Aspergillus sp. and Penicillium sp. fungi degradaded for 30 days. The samples were exposed to the fungi and their mass loss, chemical structure, hydrophilicity, and morphology were observed as a function of inoculation time and processing cycles. Our results indicate that thermo-mechanical degradation favors the deposition of fungi in the samples and enables changes in film morphology and hydrophilicity.

Effect of Ethylene–Butylacrylate–Glycidyl Methacrylate on Compatibility Properties of Poly (butylene terephthalate)/ Thermoplastic Polyurethane Blends

Effect of Ethylene–Butylacrylate–Glycidyl Methacrylate on Compatibility Properties of Poly (butylene terephthalate)/ Thermoplastic Polyurethane Blends

On wear of 3D printed Al2O3 reinforced Nylon6 matrix based functional prototypes

The use of fused deposition modelling (FDM) based functional prototypes for wear resistance applications is presently limited mainly because of selective material availability of filament materials. Various research groups have reinforced several fillers in thermoplastic base to prepare feedstock filaments to improve the mechanical properties and to address the reusability issue of polymeric waste. But hitherto the effect of Al2O3 particle sizes (as single, dual and triple particle size as reinforcement) in Nylon6 thermoplastic blend has been less explored. In the present investigation an effort has been made to prepare feed stock filament for 3D printing application to explore its wear resistant properties. The current investigation suggested that dual particle size reinforced pin exhibit better wear properties followed by triple and single particle reinforced pins. The wear tracks obtained in this study shows that dual particle size based composite material is highly wear resistant as compared to virgin acrylonitrile butadiene styrene (ABS)/ Nylon6. The results have been supported by scanning electron microscopy (SEM) images of prepared pins for wear testing.

Mechanical, thermal and antibacterial performances of acrylonitrile butadiene rubber/polyvinyl chloride loaded with Moringa oleifera leaves powder

A thermoplastic elastomeric blend from acrylonitrile butadiene rubber (NBR) and plasticized polyvinyl chloride (PVC) in the ratio (1:1) was prepared. This blend was loaded with different concentrations of mechanically ground fine powder of Moringa oleifera (MO) leaves that have an antibacterial activity, to form polymeric-based composites. The prepared composites were characterized to investigate their surface morphology and swelling behaviors. Besides, their mechanical and thermal properties were investigated. The tensile and hardness properties increased upon loading (MO) up to 20 phr. Thermogravimteric analysis (TGA) and derivative thermogravimetry (DTG) curves did not show complete deterioration upon introducing MO into the polymeric matrix. Differential scanning calorimetry (DSC) showed some shifts in the endo- and exotherms of DSC curves for PVC and NBR/PVC blend in the presence and in the absence of M. oleifera. The samples were tested biologically against Gram-positive and Gram-negative bacteria to show significant antibacterial activities. The antibacterial potency of the NBR/PVC blend increased with elevating the concentration of MO powder from 5 to 25% by mass.

Compatibilization of natural rubber–polypropylene thermoplastic elastomer blend

The effects of the addition of epoxidized natural rubber/maleic anhydride-grafted polypropylene blend as a compatibilizing agent (CA) on the properties of natural rubber (NR)/polypropylene (PP) thermoplastic elastomer blend were studied. The blends were prepared in the molten state at 180°C using a Brabender Plasticorder at a rotor speed of 60 r min−1. Evidence of compatibilization was obtained from the Brabender plastograms and from the mechanical properties results as well as the morphological analysis. It was found that the addition of the CA at different contents resulted in an increase of the tensile strength and Young’s modulus and a decrease of the elongation at break. It was also found that the melting temperature remained unchanged, the % crystallinity decreased, but the thermal stability was not affected. The morphology revealed a more homogeneous distribution of the dispersed PP phase for the CA-containing systems compared to the control NR/PP blend. These effects were attributed to the interactions that developed with the blend constituents through the functional groups of the CA.

Nanocellular Polymers with a Gradient Cellular Structure Based on Poly(methyl methacrylate)/Thermoplastic Polyurethane Blends Produced by Gas Dissolution Foaming

AbstractGraded structures and nanocellular polymers are two examples of advanced cellular morphologies. In this work, a methodology to obtain low‐density graded nanocellular polymers based on poly(methyl methacrylate) (PMMA)/thermoplastic polyurethane (TPU) blends produced by gas dissolution foaming is reported. A systematic study of the effect of the processing condition is presented. Results show that the melt‐blending results in a solid nanostructured material formed by nanometric TPU domains. The PMMA/TPU foamed samples show a gradient cellular structure, with a homogeneous nanocellular core. In the core, the TPU domains act as nucleating sites, enhancing nucleation compared to pure PMMA and allowing the change from a microcellular to a nanocellular structure. Nonetheless, the outer region shows a gradient of cell sizes from nano‐ to micron‐sized cells. This gradient structure is attributed to a non‐constant pressure profile in the samples due to gas desorption before foaming. The nucleation in the PMMA/TPU increases as the saturation pressure increases. Regarding the effect of the foaming conditions, it is proved that it is necessary to have a fine control to avoid degeneration of the cellular materials. Graded nanocellular polymers with relative densities of 0.16–0.30 and cell sizes ranging 310–480 nm (in the nanocellular core) are obtained.