High Density Polyethylene Blends Research Articles

Influence of halloysite nanotubes on processing, structural and thermal properties of poly(vinyl chloride)/high-density polyethylene composites with wood flour

ABSTRACT The aim of this work was to investigate the effect of halloysite nanotubes (HNT) on the processing, structural and thermal properties of poly(vinyl chloride) (PVC), high-density polyethylene (HDPE), and PVC–HDPE composites with various proportions of both polymer components containing 30 wt% wood flour (WF) and 5 wt% halloysite processed in the Brabender measuring mixer. The HNT content in the composites leads to a slight increase in the maximum torque and a reduction in the gelation time for PVC and PVC–HDPE matrix composites with the 90:10 component ratio. In addition, microscopic images of these materials showed a homogeneous distribution of HNT in the polymer matrix. The addition of mineral filler to the matrix, regardless of the polymer type, resulted in a slight increase in the torque values at the kneading endpoint. The PVC–HDPE–wood flour composites are characterized by higher thermal stability at processing temperature when HNT is loaded. The introduction of 5 wt% HNT into the PVC–HDPE 90:10 30 wt% WF blend resulted in an increase of the 2% weight loss temperature by 16°C. The simultaneous use of wood flour and halloysite as fillers for PVC–HDPE blends could be an eco-efficient solution for the new composite material sector.

Effects of High-Density Polyethylene (HDPE) and Additives Fuel Blends on Diesel Engine’s Performance and Emissions and NOx Prediction using Boosted Tree Model

The rising demand for eco-friendly and sustainable fuel options has prompted the investigation of alternative energy sources. This study explores the use of blends of High-Density Polyethylene (HDPE), and 7% biodiesel (B7) with additives as a substitute for diesel fuel. The research involves comparing three different mix ratios of HDPE and additives with a conventional B7 blend: a control of 100% B7, a mix of 90% B7 with 10% HDPE, and a blend of 85% B7 with 10% HDPE and 5% additives. Fourier Transform Infrared (FTIR) spectroscopy was employed to identify the fuels' functional groups. The study also measured key performance metrics, including brake-specific fuel consumption (BSFC), brake power (BP), and exhaust emissions of nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), and carbon dioxide (CO2). A Boosted Tree Model was used to establish a prediction and analysis of NOx emissions. The findings indicate that incorporating additives into the HDPE blend positively influences both engine performance and emissions. The combination of HDPE and additives with B7 resulted in reduced emissions across various engine loads and speeds, decreasing hydrocarbon and carbon-containing emissions. The Boosted Tree Model, with a configuration of 4 leaf nodes, demonstrated strong predictive accuracy, with a coefficient of determination (R2) of 0.86 and a root-mean-square error (RMSE) of 0.38 for the training dataset, and R2 of 0.97 with RMSE of 0.16 for the validation dataset. The study underscores the benefits of integrating HDPE and additives into diesel blends, highlighting their potential to lower emissions and supporting the search for viable alternative fuels.

Composition Dependence of Flow-Induced Crystallization in High-Density Polyethylene/Isotactic Polypropylene Blends.

Polyolefins, including high-density polyethylene (HDPE) and isotactic polypropylene (iPP), account for over half of the worldwide plastics market and have wide-ranging applications. Recycling of these materials is hindered due to separation difficulties as co-mingled blends of HDPE and iPP often exhibit brittle mechanical behavior because phase separated domains detach under stress due to low interfacial adhesion. Motivated to improve mechanical properties of mixed recyclates during processing, this work examines the effect of shear on the crystallization kinetics and rheological properties of HDPE-iPP blends utilizing a combination of differential scanning calorimetry (DSC), rheo-Raman spectroscopy, polarized optical microscopy, and scanning electron microscopy (SEM). In the quiescent experiments, the crystallization temperature as a function of blend composition exhibits a distinct decrease when the iPP forms the droplet phase, as expected, due to fractionated crystallization. In the presence of shear, we find elongated domains due to high capillary number. Unexpectedly, we find a compositional dependence to the flow-induced crystallization (FIC) of iPP: stronger FIC is observed in all blends compared to the pure iPP. Moreover, the flow completely counteracts the reduced crystallization arising from fractionated crystallization, indicating that the flow is able to induce nucleation in droplets to an extent such that it offsets the reduction in active nucleating agents in finite size droplets. We attribute these effects to differing microflow fields in the various morphologies as the iPP domains deform under shear.

Non-isothermal crystallization kinetics and activation energy modeling of carbon nanotubes dispersed high-density polyethylene and polypropylene blends

The study presents the effect of the reinforcement of carbon nanotubes (CNT) into high-density polyethylene (HDPE) and polypropylene (PP) blends. The Avrami exponent of CNT blends ranges within the 1.3–1.6 range. It demonstrates the 3D growth of crystals and nucleation activity during crystallization. The change in the Ozawa exponent indicates a two-stage crystallization process. The values of the Mo exponent show that the nucleation activity is affected by changing temperatures during the cooling process and the formation of high-quality crystal growth. The activation energy of the HDPE/PP matrix is 420.5 kJ/mol and adding 1.5% CNT resulted in 369.9 kJ/mol for Run-3. The polymer chains encounter difficulties in transitioning during the cooling process and release a significant amount of energy. The composition of the nanofiller in the blend affects the nucleation activity of the crystals. The permeability of the pure HDPE/PP sample obtained from sorption studies is 1.05 × 10−5 m2/s and adding 1.5% CNT in Run-3 provides a permeability of 5.2 × 10−5 m2/s. The CNT has a homogeneous dispersion in the matrix to form a net-like morphology. The crystallinity index calculated using the Seagal method for HDPE/PP, Run-3, Run-4 and Run-5 is 75%, 75.8%, 77.34% and 78%, respectively.

Quantifying the content of various types of polypropylene in high density polyethylene blends

To enhance the effectiveness of mechanical plastic recycling, it is best to separate different types of plastic during collection and recycling. This ensures the integrity and quality of recycled materials. For instance, the presence of polypropylene (PP) in recycled polyethylene (PE) can result in inconsistent and undesirable material, impacting the quality and performance of the recycled PE. This underscores the need for an analytical technique to accurately detect the presence of PP in recycled PE materials. In this study, we propose a quantitative analysis using a solution-based crystallization elution fractionation (CEF) technique to assess the polypropylene (PP) content in high-density polyethylene (HDPE) blends. The proposed methodology inherently distinguishes between the semi-crystalline PP matrix, including Homo-PP and Random copolymer PP, as well as the non-crystalline copolymer PP, and then quantifies each segment. A series of commercially available Ziegler–Natta catalyzed polymers were used to obtain the calibration curves per different type of PP materials, i.e., Homo-PP and Random copolymer PP. These calibration curves were then utilized to quantify Homo PP and copolymer PP (either semi-crystalline ethylene-propylene or amorphous ethylene-propylene) in different virgin polymer blends. The proposed methodology provides a comprehensive approach to characterizing the polypropylene content within polyethylene systems, especially in the context of qualifying polyolefin recyclate or polymer blends.

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.

Thermal, Morphological, Mechanical, and Biodegradation Properties of Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide)/High-Density Polyethylene Blends.

Polymer blends of poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) and high-density polyethylene (HDPE) with different blend ratios were prepared by a melt blending method. The thermal, morphological, mechanical, opacity, and biodegradation properties of the PLLA-PEG-PLLA/HDPE blends were investigated and compared to the PLLA/HDPE blends. The blending of HDPE improved the crystallization ability and thermal stability of the PLLA-PEG-PLLA; however, these properties were not improved for the PLLA. The morphology of the blended films showed that the PLLA-PEG-PLLA/HDPE blends had smaller dispersed phases compared to the PLLA/HDPE blends. The PLLA-PEG-PLLA/HDPE blends exhibited higher flexibility, lower opacity, and faster biodegradation and bioerosion in soil than the PLLA/HDPE blends. Therefore, these PLLA-PEG-PLLA/HDPE blends have a good potential for use as flexible and partially biodegradable materials.

Co-pyrolysis of animal manure and plastic waste study using TG-FTIR analysis

In this paper, the co-pyrolysis of blends of animal manure (AM) and high-density polyethylene (HDPE) waste was investigated using micro-thermal analysis techniques. Thermogravimetry coupled with Fourier-transform infrared spectroscopy was used to study the process kinetics and potential synergistic effects during co-pyrolysis. Dynamic co-pyrolysis experiments of animal manure (AM) and polyethylene (PE) blends in proportions of (90:10 %) and (80:20 %) were conducted at heating rates of 5, 10, 15, and 20 °C/min under an N2 atmosphere. The process was analyzed and compared to the results obtained in the pyrolysis of pure components. AM and PE co-pyrolysis exhibited a synergic effect on the pyrolysis process, leading to a favorable change in the CPI pyrolysis initiation index. This was observed in the FTIR, shifting maximum devolatilization peaks by 14 °C towards lower temperatures and a lower activation energy of the main pyrolysis stage, with a decrease from 341.49±4.65 kJ/mol to 273.04±6.93 kJ/mol after the addition of 20 wt% PE to the blend. During co-pyrolysis, the main compounds observed in the FTIR absorption spectra were CO2, CO, CH4, NH3, and aromatic hydrocarbons from AM pyrolysis. Additionally, there was an increase in CH4 and short-chain hydrocarbons due to the PE pyrolysis.

Melt-crystallization and self-nucleation of UHMWPE/bi-HDPE blends: The combined role of composition and molecular weight

Blends of bi-modal high-density polyethylene (bi-HDPE) and ultra-high molecular weight polyethylene (UHMWPE) with varying content (0–30 wt%.) and different molecular weights (MWs) (2.2, 3.5, and 4.5 M g/mol) of UHMWPE were prepared. The effect of UHMWPE content, MW, and their interplay on the microstructure, nucleation, and crystallization behavior of bi-HDPE was examined through rheology, scanning electron microscopy, and differential scanning calorimetry. The results revealed that UHMWPE serves as a partially miscible nucleating agent, effectively dispersing in the bi-HDPE matrix up to 5 wt%, thereby promoting the transition from randomly dispersed lamellae to a spherulitic morphology. The nucleating effect saturated when the UHMWPE content reached 10 wt%, leading to a diminished spherulitic structure. Beyond 10 wt% of UHMWPE, an anti-nucleation effect with segregated crystalline regions emerged. Isothermal kinetics analysis also revealed the highest crystallization rate at the optimum UHMWPE content of 5 wt%, where the critical nucleation energy barrier and fold-surface free energy were minimized. Apart from the UHMWPE content, signs of nucleation enhancement were slightly more pronounced in the bi-HDPE blend with the lowest molecular weight of UHMWPE. This phenomenon results from increased concentration fluctuations due to the larger interfacial area, as postulated from entanglement density measurements. For the first time, self-nucleation (SN) analysis revealed that the incorporation of 5 wt% of UHMWPE into bi-HDPE resulted in a wider Domain II width, indicating an increased memory effect. Notably, the crystalline memory was more pronounced in the blend containing UHMWPE with the MW of 2.2 M g/mol, exhibiting the super-nucleating effect with the highest nucleation efficiency of 218 %.

Morphological analysis of mechanically recycled blends of high density polyethylene and polypropylene with strong difference in melt flow index

Polyolefin (PO) blends are difficult to separate due to density and chemical structure similarities. The associated waste treatment in the context of mechanical recycling is therefore complicated by the establishment of multi-phase morphologies that are not yet fully understood. In the present work, a high density polyethylene (HDPE) with a very high melt flow index (MFI) and a polypropylene (PP) with a very low MFI are deliberately mingled to better understand the full spectrum of morphological variations for PO blending. The linkage with the control over injection mold-based mechanical properties such as tensile strength, elasticity modulus, elongation at break, and impact strength is made. This is done supported by the connecting of experimental analyses at different scales, including (i) the molecular scale via size exclusion chromatography and Fourier transform infrared spectroscopy (FTIR), and (ii) the meso-scale via scanning electron and polarized light microscopy as well as differential scanning calorimetry, including a differentiation between the bulk and surface region. Emphasis is both on blends processed once and re-processed either once, twice or three times. For the single processing, it is demonstrated that in most cases a droplet morphology is obtained, with smaller droplets in case HDPE is the minor component and with a dominance of HDPE at the surface even for 60% PP, due to a better HDPE flowability. It is further shown that the scission of PP chains and crosslinking of HDPE chains respectively facilitates and inhibits crystallization, at least if meso-scale -mixing as more evident during re-processing is not taking over. It is also highlighted that the properties of PP can be enhanced by adding up to 10 wt% HDPE, acting as a filler, and that the (ideally) reprocessed blends remain suitable for application.

The Effect of Processing Conditions on the Microstructure of Homopolymer High-Density Polyethylene Blends: A Multivariate Approach.

In this work, a multivariate approach was utilized for gaining some insights into the processing-structure-properties relationships in polyethylene-based blends. In particular, two high-density polyethylenes (HDPEs) with different molecular weights were melt-compounded using a twin-screw extruder, and the effects of the screw speed, processing temperature and composition on the microstructure of the blends were evaluated based on a Design of Experiment-multilinear regression (DoE-MLR) approach. The results of the thermal characterization, interpreted trough the MLR (multilinear regression) response surfaces, demonstrated that the composition of the blends and the screw rotation speed are the two most important parameters in determining the crystallinity of the materials. Furthermore, the rheological data were examined using a Principal Component Analysis (PCA) multivariate approach, highlighting also in this case the most prominent effect of the weight ratio of the two base polymers and the screw rotation speed.

Investigation of the influence of mineral fillers on the structural and mechanical characteristics of polyethylene high-density (PEHD) composites reinforced with alumina and talc

This study explores the impact of incorporating a blend of alumina and talc, ranging from 1 to 7%, into high-density polyethylene (HDPE) to modify its structural, rheological, and mechanical properties. Comparative evaluations with HDPE/Alumina and HDPE/Talc composites were conducted. The dual-filler combination was achieved through dry grinding, followed by melt processing with a Brabender plastograph. FTIR spectroscopy analysis of HDPE/ (alumina + talc) composites revealed interactions between aluminum and oxygen, with a peak at 700 cm-1 indicating alumina integration into the HDPE matrix, influencing composite properties. Impact strength decreased with talc inclusion but significantly improved with alumina. Notably, a 5% blend of HDPE/(alumina-talc) fillers exhibited the highest impact resistance. Tensile stress showed peaks at 1% talc content and a 3% filler mixture, emphasizing synergistic effects and talc's superiority over alumina. Synergism in elongation at break was observed for HDPE/ (alumina + talc) composites. Additionally, HDPE/Alumina composites displayed the highest modulus of elasticity, while HDPE/(Alumina + Talc) composites had the highest melt flow index. Surface treatments promoted uniform filler dispersion within the HDPE matrix, enhancing mechanical properties. Overall, composites with binary fillers harnessed synergistic effects, combining advantages from both components

Identification of Plastics in Mixtures and Blends through Pyrolysis-Gas Chromatography/Mass Spectrometry.

In this paper, the possibility of detecting polymers in plastic mixtures and extruded blends has been investigated. Pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) allows researchers to identify multicomponent mixtures and low amounts of polymers without high spatial resolution, background noise and constituents mix interfering, as with molecular spectrometry techniques normally used for this purpose, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy and differential scanning calorimetry (DSC). In total, 15 solid mixtures of low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyamide (PA) and polycarbonate (PC) in various combinations have been qualitatively analyzed after choosing their characteristic pyrolysis products and each polymer has been detected in every mix; thus, in extruded blends of high-density polyethylene (HDPE), PP and PS had varying weight percentages of the individual constituents ranging from 10 up to 90. Moreover, quantitative analysis of these polymers has been achieved in every blend with a trend that can be considered linear with coefficients of determination higher than 0.9, even though the limits of quantification are lower with respect to the ones reported in the literature, probably due to the extrusion process.

Modifications of Phase Morphology, Physical Properties, and Burning Anti-Dripping Performance of Compatibilized Poly(butylene succinate)/High-Density Polyethylene Blend by Adding Nanofillers.

A twin-screw extruder was used to fabricate poly(butylene succinate) (PBS)/high-density polyethylene (HDPE) blends (7:3 weight ratio) and blend-based nanocomposites. Carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and organoclays (15A and 30B) served as the nanofiller, while maleated HDPE (PEgMA) acted as an efficient compatibilizer for the blend. In the composites, individual nanofillers were mostly localized in HDPE domains, but some fillers were also observed at PBS-HDPE interfaces. The sea-island morphology of the compatibilized blend evolved into a pseudo-co-continuous morphology in the composites. Differential scanning calorimetry results confirmed that PEgMA with HDPE evidently accelerated the crystallization of PBS in the blend. The possible nucleation effect of added fillers on PBS crystallization was obscured by the formation of quasi-connected HDPE domains, causing fewer PBS nucleation sites. The presence of nanofillers improved the thermal stability and burning anti-dripping behavior of the parent blend. The anti-dripping efficiency of added fillers followed the sequence CNT > 15A > 30B > GNP. The rigidity of the blend was increased after the formation of nanocomposites. In particular, adding GNP resulted in 19% and 31% increases in the Young's modulus and flexural modulus, respectively. The development of a pseudo-network structure in the composites was confirmed by measurement of rheological properties. The electrical resistivity of the blend was reduced by more than six orders of magnitude at 3 phr CNT loading, demonstrating the achievement of double percolation morphology.

Thermomechanical Properties of Virgin and Recycled Polypropylene-High-Density Polyethylene Blends.

This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in recycled polymer blends is of critical importance in order to facilitate the re-entering of recycled materials to the consumer market and, thus, contribute towards a circular economy. This is an area that requires further research due to the inhomogeneity of recycled materials. Therefore, the thermal and mechanical properties of virgin and recycled polypropylene/high-density polyethylene blends were investigated systematically. Differential scanning calorimetry concludes that both the recycled and virgin blends are immiscible. Generally, recycled blends have lower overall crystallinity and melting temperatures compared with virgin blends while, remarkably, their crystallisation temperatures are compared favourably. Dynamical mechanical analysis showed little variation in the storage modulus of recycled and virgin blends. However, the alpha and beta relaxation temperatures are lower in recycled blends due to structural deterioration. Deterioration in the thermal and mechanical properties of recycled blends is thought to be caused by the presence of contaminants and structural degradation during reprocessing, resulting in shorter polymeric chains and the formation of imperfect crystallites. The tensile properties of recycled blends are also affected by the recycling process. The Young's modulus and yield strength of the recycled blends are inferior to those of virgin blends due to the deterioration during the recycling process. However, the elongation at break of the recycled blends is higher compared with the virgin blends, possibly due to the plasticity effect of the low-molecular-weight chain fragments.

Morphology and Mechanical Properties of High Density Polyethylene and Ethylene-Methyl Acrylate Copolymer Blends with Organoclay

In this research, the effect of ethylene-methyl acrylate copolymer (EMAC or EMAC30) and clay surface modified with aminopropyltriethoxysilane 0.5-5 wt% and octadecylamine 15-35 wt% (Clay-ASO) on the morphological, mechanical, and thermal properties of high density polyethylene (HDPE) were investigated. The polymer blends and composites were prepared by an internal mixer and then samples were molded by compression molding. The morphology analysis showed that the presence of fibrous surface at the specimen fracture surface of HDPE/EMAC30 blends. The phase morphology of HDPE blends with Clay-ASO 3, 5 and 7 phr was observed the phase separation of EMAC30 and aggregate of Clay-ASO at high EMAC30 content. Young’s modulus of HDPE/Clay-ASO composites increased with increasing Clay-ASO composites. The presence of Clay-ASO did not improve Young’s modulus and tensile strength of HDPE/EMAC30/Clay-ASO composites. The strain at break of HDPE/EMAC30 blends increased with increasing EMAC30 content. The incorporation of EMAC30 and Clay-ASO had no effect on the melting temperature of HDPE blends and composites, respectively. The percent crystallinity of HDPE/EMAC30 and HDPE/EMAC30/Clay-ASO was lower than that of pure HDPE. The addition of EMAC30 and Clay-ASO decreased the degradation temperatures of HDPE/EMAC30 blends and composites.

Plastic Waste Valorization for Fused Deposition Modeling Feedstock: A Case Study on Recycled Polyethylene Terephthalate/High-Density Polyethylene Sustainability

In this study, material development, characterization, and sustainability assessment are performed on blends from recycled post-consumer commodity plastics for fused deposition modeling (FDM) filament extrusion. A recycled polyethylene terephthalate (rPET) and high-density polyethylene (rHDPE) blend 80:20 ratio is modified using three different methods: compatibilization with Maleic Anhydride, surface functionalization of PET with sodium dodecyl sulphate (SDS), and hybridization by combination of the two methods which is a novel approach. The selected blends were reinforced with chopped glass fibers and characterized. The printability of blends was assessed, and the dimensional accuracy of the prints was calculated. In addition, a cost estimation and comparison between the developed blends and the commercially available FDM filaments was carried out. Finally, life cycle assessment (LCA) was conducted for each prepared blend to facilitate the decision of the optimum blend in relation to mechanical properties and environmental performance and hence correlate the material, economic, and sustainability advantages.

Dynamic structure transformation of char precursors during co-pyrolysis of coal and HDPE by using ReaxFF MD simulation and experiments

Understanding the effects of co-pyrolysis synergies between low-rank coal and high-density polyethylene (HDPE) on the carbon structure evolution in char and the relationship between char structure and chemical bonds evolution is very needed. A combination of ReaxFF MD and experimental approaches provides an opportunity for fully understanding the dynamic profiles of char structures and coking trends during co-pyrolysis process of coal and HDPE. In this work, consistent conclusions were obtained from fixed-bed experiments and ReaxFF MD simulations in product distribution during both individual coal pyrolysis and co-pyrolysis at different temperatures. The ReaxFF MD simulation results reveal that adding HDPE partially inhibited the coking process of coal char. The RDF results indicated higher order degree and aromaticity exist in coal/HDPE(7:3)-Char when compared to those in coal-Char, which agrees well with the findings from XRD and FTIR approaches. By analyzing the evolution of C=C, C=O, C-O, C(sp2)-C(sp3), C(sp3)-C(sp3) and C(sp2)-H bonds in C40+ fragments during secondary simulations of co-pyrolytic char, it was observed that the structural order and aromaticity of co-pyrolytic char increase with temperature, and the oxygen-containing bonds are the initial recombination sites for char formation. These findings provide rich theoretical information to complement the understanding of char structure in co-fed systems and the interaction between coal and HDPE blend.

High density polyethylene and butanol-gasoline blends: A material compatibility study

We are now well on the path of transitioning away from the fossil fuel resources on cutting down their consumption as much as possible. The fuels chosen for this study include ethanol-butanol (EB) -gasoline, acetone-butanol-ethanol (ABE) -gasoline and methanol-butanol (MB) -gasoline blends. High density polyethylene (HDPE) is a polymer that is extensively used in several auto parts and fuelling infrastructure materials. Incompatibility between these blends and fueling infrastructure system should be studied comprehensively for the adoption of these alternative fuels to be faster and hassle free. This study intends to gauge the changes in HDPE because of its immersion in the gasoline-alcohol blends mentioned for a period of 4, 30 & 90 days. The changes were ascertained by studying the mass, tensile strength, elongation, and hardness of the samples before and after immersion into blends. Sophisticated techniques were used to characterize the morphological and chemical changes of the polymer. The results showed that there was an increase in the mass of the HDPE samples as a result of the absorption of the blends by the polymeric samples. A decrease in tensile strength and hardness values were recorded for the samples whereas the elongation values were found to increase. Studies revealed that there was neither fuel degradation nor any oxidative degradation of the polymeric sample. The results indicated an increase in the mass and elongation of the HDPE as a result of the absorption of the fuel leads to lesser stable polymeric matrix and decrease in the percentage crystallinity. Hence this investigation led us to the conclusion that all the fuels blends studied are highly compatible with HDPE, even in instances where a change in the mechanical properties is seen, it is similar to that seen in gasoline.

Evaluation of the Mechanical, Thermal and Rheological Properties of Hop, Hemp and Wood Fiber Plastic Composites.

The aim of this study was to evaluate the use of waste natural fibers from milled hop bines and hemp stalks, without chemical treatment, and compare them to a commercial wood fiber for use in wood-plastic composite (WPC) materials. The fibers were characterized (density, fiber size and chemical composition). WPCs were produced by the extrusion of a blend of fibers (50%), high-density polyethylene (HDPE) and coupling agent (2%). The WPCs were characterized for their mechanical, rheological, thermal, viscoelastic and water resistance properties. Pine fiber was about half the size of hemp and hop fibers and thus had a higher surface area. The pine WPC melts had a higher viscosity than the other two WPCs. Additionally, the tensile and flexural strengths of the pine WPC were higher than those of hop and hemp WPCs. The pine WPC was also shown to have the least water absorption followed by hop and hemp WPCs. This study highlights that different lignocellulosic fibers influence their WPC properties. The properties of the hop- and hemp-based WPCs were comparable to commercial WPCs and can be improved by further milling/screening the fibers to a smaller particle size (volumetric mean of ~88 μm) to increase their surface area, fiber-matrix interactions and improve stress-transfer.