Plastic Blends Research Articles

Isothermal combustion kinetics of synthetic refuse plastic fuel (RPF) blends by thermogravimetric analysis

Thermal behavior of wastewater sludge, plastic and synthetic blends during combustion process was studied to identify potential of refused derived fuel application. Experiments were conducted in a large-scale thermogravimetric analyzer at temperatures ranging from 400°C to 700°C in the presence of air flow at 8L/min. Isothermal modeling was performed to find system kinetic parameters including combustion reaction rate constant (k), order of reaction (n), Arrhenius pre-exponential factor (A) and activation energy (E). Results revealed that with increase in temperature from 400°C to 700°C, maximum rate of combustion was observed to increase from 1.6%/min to 7.12%/min and 2.09%/min to 21.9%/min for wastewater sludge and plastics, respectively. The corresponding time for maximum weight loss rate was observed to decrease from 15min to 3.1min for wastewater sludge and from 47min to 3.8min for plastic. Thermogravimetric profile and activation energy indicated that refuse plastic fuel blends with higher percentage of plastic required higher activation energy than wastewater sludge from 12.43kJ/mol to 58.60kJ/mol. Experimental results show the potential to explain and predict combustion behavior and activation energy of combustion of wastewater sludge and plastic blends in practical RPF applications.

Effects on Oxygen‐barrier Properties of Pretreating Paperboard with a Starch–Poly(Vinyl Alcohol) Blend before Polyethylene Extrusion

Polyethylene (PE) extrusion coating was performed on paperboard pre‐coated with water‐borne barrier coatings based on starch–poly(vinyl) (PVOH)–plasticizer blends in order to investigate that how the addition of a plasticizer to the pre‐coating affects the oxygen‐barrier properties of the board after PE extrusion coating. The plasticizers used were glycerol, polyethylene glycol (PEG) and citric acid (CA). Photomicrographs showed that the barrier coating layers were rather smooth, but defects were observed in the starch–PVOH layers when a plasticizer was added. Starch–PVOH layers had oxygen‐barrier properties similar to those of pure PVOH without plasticizers. When a sufficient number of layers (four layers) were applied to cover defects, the starch–PVOH layers containing CA showed oxygen transmission rate (OTR) values similar to those of starch–PVOH layers without plasticizer. The adhesion of PE to pre‐coated paperboard decreased when a plasticizer was added to the pre‐coating recipes. PE extrusion coating resulted in a reduction in the OTR in the case of pre‐coating formulations containing plasticizers. A lower OTR after polyethylene extrusion was observed with PEG as plasticizer than with CA as plasticizer. This could be explained by the increase in brittleness due to cross‐linking under the high temperature load during the extrusion process. Dynamic mechanical analysis of the films showed a substantial increase in storage modulus between 100°C and 200°C for CA‐containing starch–PVOH films. The contact angle of diiodomethane on the pre‐coating layer decreased when a plasticizer was added to the coating recipe indicating an increase in wetting of the PE melt. Addition of PEG to the pre‐coating led to a greater wetting than the addition of CA, and this may have sealed some defects in the pre‐coating leading to lower OTR values.

The Influence of Compatibilizer Addition and Gamma Irradiation on Mechanical and Rheological Properties of a Recycled WEEE Plastics Blend

Waste electrical and electronic equipment (WEEE) is growing rapidly, and the plastics within WEEE have an important role in fulfilling the recovery and recycling targets defined in the European WEEE Directive. This study considers recycling of WEEE plastics by making a blend of the different plastics instead of separating them. The mechanical and thermal properties can be enhanced by adding a compatibilizer. It was found that one compatibilizer, a styrene-b(ethylene-co-butylene)-b-styrene (SEBS) copolymer named Kraton® G1652 E, had a large impact on the ductility of the recycled WEEE plastics blend. By adding 2.5 weight % (wt%) of this copolymer, the elongation at break increased by more than five times compared with the non-compatibilized samples, with only a small decrease in stiffness and strength. The storage modulus (G’) decreased slightly with increasing compatibilizer amounts while the impact strength increased with increasing amounts of compatibilizer, from 2.1 kJ/m2 (reference material) to 3.6 kJ/m2 (5 weight % (wt%) compatibilizer). It was found that Kraton® FG1901 E (styrene-b(ethylene-co-butylene)-b-styrene (SEBS) grafted with maleic anhydride (MAH)), Royaltuf® 372P20 (styrene acrylonitrile (SAN) modified with ethylene-propylene-diene elastomers (EPDM)) and Fusabond® P353 (polypropylene (PP) with a high degree of grafted MAH) were ineffective as compatibilizers to the blend. Gamma irradiation (50 kGy) did not improve the mechanical properties however: the impact strength of the gamma-irradiated samples was lower than that of the non-irradiated samples.

Mechanical and Thermal Characterization of Melt-Filtered, Blended and Reprocessed Post-Consumer WEEE Thermoplastics

A melt-blended and melt-filtered real post-consumer and recyclable waste electrical and electronic equipment plastics blend (WEEEBR) was studied, where the WEEEBR contained mainly acrylonitrile-butadiene-styrene copolymer (~40 wt %), high impact polystyrene (~40 wt %) and polypropylene (~10 wt %). The main aim was to better understand the influence of different reprocessing conditions on the mechanical and thermal properties of WEEEBR and to compare these properties with the corresponding properties of model material blends of samples from single screw extrusion, twin screw extrusion and injection molding. For all the reprocessing alternatives studied, WEEEBR was found to be processable and an acceptable surface character could be obtained within narrow processing condition windows. It was found in particular that the reprocessing conditions influenced the elongation at break of WEEEBR, and to a lesser extent also the width of the polypropylene melting temperature region. The highest yield stress and elongation at break of WEEEBR was obtained after twin-screw extrusion at low barrel temperatures (180–200 °C) and a low screw rotation rate (60 rpm). Injection molding produced brittle materials with low impact strength, possibly due to molecular orientation effects.

Enhancement of mechanical properties of waste-sourced biocomposites through peroxide induced crosslinking

The enhancement of mechanical performance of waste-sourced biocomposites through peroxide induced crosslinking was investigated in order to expand their range of applications. Biocomposites containing 25 to 35wt% of residual Kraft-pulp cellulose fibers, 1.5wt% of a selected maleic-anhydride-modified polyethylene coupling agent and a 60/40 (w/w) of recycled agricultural plastic/post-consumer plastic blend were compounded in an extrusion-compounding pilot-plant. Changes in the blend structure due to the presence of the organic peroxide used were studied by spectroscopy and thermal analysis. It was found that the addition of extremely low amounts of peroxide (0.025–0.050wt%) results in remarkable improvements in stiffness, strength and toughness of biocomposites, without compromising processability. Thus, their tensile strength and energy at break increased up to 89.4% and 138%, respectively, with regard to uncrosslinked biocomposites. Scanning electron microscopy revealed an improvement of the fiber–matrix adhesion due to the treatment with the peroxide.

Tailored Nanostructured Thermoplastic Elastomers from Polypropylene and Fluoroelastomer: Morphology and Functional Properties

Conventional thermoplastic elastomer from rubber–plastic blends has rubber domains of a few micrometers dispersed in a plastic matrix. Nanotailoring of novel thermoplastic elastomeric blends from polypropylene (PP) and fluoroelastomer (FKM) by a special green technique generated a unique morphology in which FKM was dispersed in the nanometer range (50–70 nm) into the continuous PP matrix. The evolution of the unique nanostructure morphology was explained with the help of a viscoelastic drop breakup mechanism. The nanostructured blends exhibited superior physical properties and outstanding oil swelling resistance and thermal stability, which increased upon vulcanization of the rubber phase in situ. For example, volume swell of nanostructured PP/FKM blends was 8–10% in ASTM oil #3 at 100 °C for 72 h, which was the lowest in this type of thermoplastic elastomer. Insights into how the unique morphology influenced the functional properties of thermoplastic elastomers was provided. These new thermoplastic elastomers can be used in the automotive industry, particularly as a liner material for car hoses where superior flexibility, oil resistance, and heat resistance are desirable properties.

Non-invasive identification of plastic materials in museum collections with portable FTIR reflectance spectroscopy: Reference database and practical applications

In this work, portable Fourier transform infrared (FTIR) reflectance spectroscopy was used for the contactless, non-invasive, and in situ analysis of historic plastics. For the first time, this paper presents the complete database of polymer spectra of a set of reference materials widely used in the cultural heritage community. Over 100 samples from the ResinKitTM and SamCo (Popart Project) collections, which also include samples such as foams, thin films, dark plastics, and other challenging materials, were analyzed. The extensive database of spectral signatures that was acquired for this work represented the departure point for a field study aiming at the identification of the components of a variety of plastic artifacts in the collections of Architecture and Design and Contemporary Art of the Art Institute di Chicago. Reflectance FTIR spectroscopy was confirmed in situ to be a fast and effective method of identification of historic plastics. In some cases, in addition to the main polymers, it was also possible to identify additives in plastic blends, such as plasticizers and inorganic fillers.

Investigation on the co-pyrolysis of waste rubber/plastics blended with a stalk additive

This study presents an experimental investigation of co-pyrolysis of discarded rubber and plastics in a tube furnace. The properties of the pyrolysis oil and solid residue under various blending ratios of rubber and plastics were investigated. The impacts of the stalk additive and the heating rate on the pyrolysis oil yield and feedstock-to-oil energy conversion efficiency (FOECE) were studied. Compared with the pyrolysis of rubber or plastics separately, the co-pyrolysis of rubber and plastics produced a higher oil yield with a higher oil heating value. When the mass fraction of the rubber was 60wt%, the pyrolysis oil yield and FOECE reached their maximum values. When adding 10% stalk additive at a rubber-to-plastics ratio of 4:1, a higher oil yield was achieved, and the oil yield increased by 10.3wt%, where the heating value of the pyrolysis oil reached 39.93MJkg−1. The stalk additive only had a slight impact on the solid residue and the completeness of the pyrolysis reactions. The stalk additive increased the FOECE and postponed the highest yield point to the 80wt% rubber blend because the greater volatility promoted the pyrolysis reaction and the production of condensable gaseous components. A higher heating rate improved the oil yield. According to the elemental analysis, a small fraction of sulfur existed in the oil. The stalk additive increased the H/C ratio in the oil. Through the GC–MS analysis, the primary components in the pyrolysis oil from the rubber and plastics blend were identified as alicyclic hydrocarbons and aromatics, whereas the oxygen-rich stalk additive increased the contents of alcohols, esters, and ketones. Overall, the stalk additive significantly improved the yield and the FOECE when co-pyrolysis of rubber/plastic blends was performed.

Fluidity of Plastic Blends with a Recycled Filler

This research paper deals with an investigation of the fluidity of plastic blends with a recycled filler. Five different blends with three filler concentrations were prepared. As a fillers were radiation crosslinked plastics used. Fluidity was determined by the spiral test where a cavity with the Archimedes spiral is used and a length of the resulting spiral is evaluated and compared. Results show that the more filler is used the worse fluidity there is; however lower concentrations have fluidity almost identical to the non-filled material and the difference is almost negligible. At higher concentrations is the difference more significant and thus it has to be taken into account. Particle size of the filler should be also taken into a consideration but its influence greatly depends on the matrix.

Analyzing the environmental impacts of laptop enclosures using screening-level life cycle assessment to support sustainable consumer electronics

The market growth of consumer electronics makes it essential for industries and policy-makers to work together to develop sustainable products. The objective of this study is to better understand how to promote environmentally sustainable consumer electronics by examining the use of various materials in laptop enclosures (excluding mounting hardware, internal components, and insulation) using screening-level life cycle assessment. The baseline material, is a fossil plastic blend of polycarbonate-acrylonitrile butadiene styrene. Alternative materials include polylactic acid, bamboo, aluminum, and various combinations of these materials known to be currently used or being considered for use in laptops. The flame retardants considered in this study are bisphenol A bis(diphenyl phosphate), triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and borax-boric acid-phosphorous acid. The Tool for the Reduction and Assessment of Chemical and other environmental Impacts v2.1 was used for the assessment of impacts related to climate change, human and ecological health, and resource use. The assessment demonstrates that plastics, relative to the other materials, are currently some of the better performing materials in terms of having the lowest potential environmental impact for a greater number of impact categories based on product life cycle models developed in this study. For fossil plastics, the material performance increases with increasing post-consumer recycled content. To best characterize and improve the environmental sustainability of bio-based materials like polylactic acid, it will be necessary to better model end-of-life options for this application. The impacts of using pressed bamboo materials in laptop enclosures can be lessened by improving key sub-processes, such as strip gluing. The final issue highlighted by this study is the need to develop more sustainable alternatives for flame retardants and fillers because they can represent a significant portion of the cradle-to-grave life cycle impacts, even though they often constitute a small portion of the weight of the final product.

Structure and property of biodegradable soy protein isolate/PBAT blends

In this study, the structure and properties of biodegradable plastic blends from soy protein isolate (SPI) and poly(butylene adipate-co-terephthalate) (PBAT) was studied. Using scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), mechanical test, and biodegradation test, the compatibility and phase behavior of the components were investigated. In the blends, SPI acted as a filler in the PBAT matrix, which exhibited a reinforcing effect on the PBAT matrix. With increasing SPI content, the tensile strength and elongation at break of SPI/PBAT blends reduced; the thermal stability decreased at 200–400°C and increased at higher temperatures. However, the blends with as high as 28.6wt% SPI still possessed a good ductility. Soy protein was easily degraded in the soil and thus made the blends biodegradable as a whole.

Sustainable eco-composites obtained from agricultural and urban waste plastic blends and residual cellulose fibers

The use of blends of recycled agricultural plastic and post-consumer high-density polyethylene from municipal solid wastes, as matrices for sustainable eco-composites, was investigated with the aim of boosting the use of recycled materials and reducing the waste plastic environmental impact. It was proposed that proper selection of blends of different waste plastics will allow the production of composites with optimized properties. The two plastics and their blends were characterized by using different spectroscopic techniques and thermal analysis, and measuring the flow curves. The eco-composites were obtained by compounding a selected blend of recycled agricultural plastic and post-consumer polyethylene with different proportions of coupling agent and waste cellulose fibers in a pilot-plant twin-screw extruder. The structure of the final materials and the role of the coupling agent were analyzed by using scanning electron microscopy. Finally, the novel eco-composites were compared to their counterparts without post-consumer polyethylene, revealing that the incorporation of polyethylene increases the strength and stiffness of the eco-composites, without compromising the impact strength. The incorporation of 40 wt% of polyethylene caused increases in moduli as high as 175% for the polymer and 47% for composites with 30% of fibers. The tensile strength increased up to 21% for the same composites. The decreases in processability caused by the incorporation of polyethylene can be corrected by increasing the coupling agent content. The improved balance between stiffness, strength and toughness without compromising processability can increase the recyclability of the polymer and cellulose wastes used in this work.

Effect of nanofiller CeO2 on structural, conductivity, and dielectric behaviors of plasticized blend nanocomposite polymer electrolyte

A novel combination of nanoparticles of rare earth oxide ceria (CeO2) dispersed in polyethylene oxide (PEO)/polyethylene glycol (PEG) blend polymer doped with cation donor salt lithium perchlorate (LiClO4), and ethylene carbonate (EC) nanocomposite polymer electrolyte (NCPE) was prepared by standard solution casting technique. The X-ray diffraction (XRD) patterns reveal that the amorphous nature of the nanocomposite has been increased considerably on dispersion of nanofiller. The complexation was further confirmed by Fourier transform infrared (FTIR) analysis. The impedance spectroscopy technique was used to measure the ionic conductivity and activation energy of the nanocomposite electrolytes. The maximum ambient temperature conductivity of 1.18 × 10−4 Scm−1 was obtained for the nanocomposite of 68 % PEO, 16 % PEG, 11 % LiClO4, 5 % EC, and 1 % CeO2 by weight percentage. The ac conductivity follows the universal power law. The variation of dielectric permittivity, dielectric loss, and modulus spectra with frequency and temperature was consistent with conductivity. The activation energy calculated from temperature-dependent imaginary modulus well coincides with that of conductivity. The loss tangent ascertains the presence of conductivity relaxation and the minimum relaxation time for highest conducting electrolyte.

Leaching behaviour and ecotoxicity evaluation of chars from the pyrolysis of forestry biomass and polymeric materials

The main objective of this study was to assess the environmental risk of chars derived from the pyrolysis of mixtures of pine, plastics, and scrap tires, by studying their leaching potential and ecotoxicity. Relationships between chemical composition and ecotoxicity were established to identify contaminants responsible for toxicity. Since metallic contaminants were the focus of the present study, an EDTA washing step was applied to the chars to selectively remove metals that can be responsible for the observed toxicity. The results indicated that the introduction of biomass to the pyrolysis feedstock enhanced the acidity of chars and promote the mobilisation of inorganic compounds. Chars resulting from the pyrolysis of blends of pine and plastics did not produce ecotoxic eluates. A relationship between zinc concentrations in eluates and their ecotoxicity was found for chars obtained from mixtures with tires. A significant reduction in ecotoxicity was found when the chars were treated with EDTA, which was due to a significant reduction in zinc in chars after EDTA washing.

New dibenzoate plasticizer blends for PVC applications

Dibenzoates plasticizers are well‐established and are used in PVC applications. Chemically, these plasticizers are non‐phthalates and function well as high‐solvating. In the past, new benzoates, dibenzoate blends, and grades were developed to keep pace with formulators' needs. More recently, a new generation of dibenzoate triblend platform has been developed to offer formulators an improved high solvator to complement general purpose plasticizer performance. A basic plastisol evaluation protocol was utilized to help determine how to formulate with these new blends. In addition to the basic data that were developed, examples of performance in starting plastisol formulations are shown. J. VINYL ADDIT. TECHNOL., 20:137–142, 2014. © 2014 Society of Plastics Engineers

Improvement of mechanical properties of recycled plastic blends via optimizing processing parameters using the Taguchi method and principal component analysis

In this paper, the Taguchi method and principal component analysis (PCA) are used to improve the mechanical properties of recycled polypropylene (PP) blends in injection moulding procedure, with detailed assessments performed on each method and comparison was made based on results of both the methods. The experimental design was carried out by adopting a L9-34 Taguchi orthodoxy array (OA), which has four controllable factors (i.e., melt temperature, mould temperature, injection speed and packing pressure) at three levels. Injection moulded specimens made from different compositions of virgin-recycled PP were tested to determine the optimal conditions for the injection moulding procedure. The effects of the processing parameters and the proportion of recycled plastic in composites on the mechanical properties were investigated, the optimal conditions for desired properties were obtained and then verified. The appropriate blending ratio of virgin and recycled plastic was evaluated. The results reveal that deteriorations in the mechanical properties of products produced from recycled plastic can be improved by optimizing the processing parameters during the injection moulding procedure.

Characterization of Gamma Irradiated Plasticized Carboxymethyl Cellulose (CMC)/Gum Arabic (GA) Polymer Blends as Absorbents for Dyestuffs

Polymer blends based on carboxymethylcellulose (CMC) and gum arabic (GA) were prepared by solution casting method. Glycerol was added to the polymer blend solution as a plasticizer with different ratios (2·5, 5, 10 and 20%). Then, the plasticized blends were exposed to gamma irradiation at different doses (5, 10 and 20 kGy). The physical properties of the plasticized polymer blends were investigated in terms of gel fraction (%) and swelling percent (%). Thermal properties were investigated by TGA. Also, the structure of the plasticized polymer blends was characterized by Fourier transform infrared spectroscopy. Scanning electron microscope was investigated in order to examine the compatibility between two polymers in the blend and also between polymer blend and plasticizer. The prepared plasticized polymer blends were used as an adsorbent for different dyestuffs. The sorption of dyestuffs by the plasticized polymer blend was determined by a method based on spectroscopic analysis. The results showed that the plasticized polymer blend has a high affinity for basic, acid, reactive and direct dyes. The obtained results showed that using glycerol as plasticizer improved the swellability of polymer blend and also the dye uptake (%).

TG/FTIR analysis on co-pyrolysis behavior of PE, PVC and PS

The pyrolysis and co-pyrolysis behaviors of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) under N2 atmosphere were analyzed by Thermal gravimetric/Fourier transform infrared (TG/FTIR). The volatile products were analyzed to investigate the interaction of the plastic blends during the thermal decomposition process. The TGA results showed that the thermal stability increased followed by PVC, PS and PE. The pyrolysis process of PE was enhanced when mixed with PS. However, PS was postponed when mixed with PVC. As for PE and PVC, mutual block was happened when mixed together. The FTIR results showed that the free radical of the decomposition could combine into a stable compound. When PE mixed with PVC or PS, large amount of unsaturated hydrocarbon groups existed in products while the content of alkynes was decreased. The methyl (CH3) and methylene (CH2) bonds were disappeared while PVC mixed with PE.

Long-Term Physical Stability of Plasticized Hemicellulose Films

Oat spelt arabinoxylan (OsAX) and spruce galactoglucomannan (GGM) are hemicelluloses that can be extracted in large quantities from side-streams of the agriculture and forest industries. They both form self-standing films, making them potential future packaging materials. This systematic study focuses on the effect of long-term storage on the physical stability of hemicellulose-based films. OsAX and GGM films were plasticized with 40% (w/w of the polysaccharide) of glycerol, sorbitol, or their blends, and their stability was followed for four months. Ageing especially affected the glycerol-containing films, in which the tensile strength and Young’s modulus increased and elongation at break decreased. Although the mechanical properties were altered, storage did not affect crystallinity of the films. Oxygen gas permeability (OP) and water vapor permeability (WVP) properties were monitored in OsAX films. Interestingly WVP decreased during storage; more than a 40% decrease was seen when plasticizer blends contained 50% or more glycerol. In contrast, there were no drastic changes in the OP during storage; all the OPs obtained were between 3.7 and 8.9 [cm3 µm/ (m2 d kPa)].

Toward computational design of efficient plasticizers for nylon

Polyamides are semi-crystalline polymers useful in a wide range of applications in the plastics industry. Some applications require higher flexibility and workability of the polyamides. Therefore, plasticizers are added to ease compounding and processing procedures and produce the desired product properties. The goal of the present study was to use computational tools to estimate plasticizer efficiency in plasticizing nylon 66/6. It is known that plasticizer efficiency is greatly influenced by structural effects of the plasticizer and the nature of the polymer, and therefore in this research, a systematic study is reported to explore these factors. A homology series of esters of 4-hydroxybenzoate with various chain lengths of the alcohol moiety was examined. Also, the efficiency of linear plasticizers was compared to branched ones and stereoisomers were considered. Plasticizer efficiency was determined by calculating cohesive energy density (CED), solubility parameters, free volume and interaction intensities of pristine nylon and the nylon–plasticizer blends. It was found that plasticizer efficiency of esters with linear alcohol moiety is higher than branched chains. Whereas plasticizer efficiency increases when the branched side chain is more bulky, no coherent trend was observed for the linear side chain of the alcohol moiety. Surprisingly, a significant difference was observed between the pair of enantiomers. The most efficient plasticizer of the eight examined was the chiral molecule (R)-2-Methylbutyl-4-Hydroxybenzoate (R-MB4HB), increasing the free volume of the nylon by 60-fold (3-fold greater than the original Methyl 4-Hydroxybenzoate (M4HB)). Copyright © 2013 John Wiley & Sons, Ltd.