Polyolefin Research Articles

Preparation process and performance of thermoplastic polyurethane/amorphous poly alpha olefin compound modified bitumen

As a bitumen modifier, waste thermoplastic polyurethane (TPU) could effectively improve the intermediate and low temperature pavement performance of bitumen and increase the recycling rate of waste. However, the high temperature performance of TPU modified bitumen is insufficient, which limits the application of TPU modified bitumen in pavement engineering. The objective of this study is to improve the high temperature performance of TPU-modified bitumen by compounding amorphous poly alpha olefin (APAO). The orthogonal test of TPU/APAO modified bitumen was conducted to determine the preparation process parameters. The physical and rheological properties of TPU/APAO modified bitumen were investigated by penetration, softening point, ductility, elastic recovery, viscosity, dynamic shear rheometer (DSR, including temperature sweep and multiple stress creep recovery), and bending beam rheometer (BBR) tests. The compatibility and modification mechanism of TPU/APAO modified bitumen were studied by storage stability, fluorescence microscopy (FM), and Fourier transform infrared spectroscopy (FTIR) tests. The test results show that the optimum preparation process of TPU/APAO compound modified bitumen is 5000 rpm for 60 min at 190 °C. The addition of APAO reduces penetration and ductility, increases softening point and viscosity of TPU modified bitumen. The low temperature performance is not sacrificed with the improvement of the high temperature PG grade. Besides, the anti-aging properties and creep recovery rate of compound modified bitumen are optimal at 2% TPU and 6% APAO. The proper content of APAO can improve the compatibility between TPU and bitumen. APAO is physically mixed with bitumen, but the free isocyanate in TPU can react with the polar carboxyl group (asphaltene) and their product is closely related to the PU bond.

Terpene resin prepared from renewable turpentine oil as a new type of cold flow improver for soybean biodiesel-diesel blends

The widespread use of biodiesel-diesel blends in society is one of the main ways to alleviate the global petrochemical energy shortage. Cold flow improvers (CFIs) can effectively improve the cold flow properties of biodiesel-diesel blends. Traditional CFIs are specific types of polymers synthesized from petrochemical products such as polymethacrylate, ethylene-vinyl acetate and poly alpha-olefin. To reduce the dependence on these non-renewable resources, terpene resin synthesized from renewable turpentine is used as a new type of CFI for biodiesel-diesel blends, and the effects of terpene resin on improving the cold flow properties of biodiesel-diesel blends are studied for the first time. The results indicate that the depression effects are extensively affected by the molecular weight of terpene resin, their addition amount and volume ratio of diesel and biodiesel in the blends. The terpene resin with an average molecular weight of 1212 presents the best depressive effect at the addition of 2000 ppm, and the cold filter plugging point (CFPP) of B30 (30 vol%. biodiesel + 70 vol%. diesel) decreases by 10 °C. Furthermore, using a differential scanning calorimeter, polarization optical microscope and rheological analysis, the paraffin crystallisation and morphology of wax crystals for diesel biodiesel-diesel blends before and after treatment with terpene resin are studied, and the mechanism of improving cold flow properties is discussed.

Trimethylolpropane trioleate as eco-friendly lubricant additive

Approximately 17.9% of fuel energy is used to overcome engine friction in passenger cars with engine frictional losses further broken down into losses along hydrodynamic (40%), elastohydrodynamic – due to pure sliding motion (40%), mixed (10%) and boundary (10%) lubrication regimes. Therefore, to assess the tribological influence of TMP trioleate as an eco-friendly additive to a low viscosity Polyalphaolefin (PAO) at different lubrication regimes, the present study adopted a Stribeck-type analysis. Through this study, the viscosity index of PAO was found to increase significantly when blended with 5-vol% TMP trioleate. Tribologically, across the tested conditions at different sliding velocities and applied normal loads, it was determined that this blend could potentially reduce friction power and wear scar diameter by up to 6.09% and 39.65%, respectively, when compared with the neat PAO. Such an improvement was demonstrated to also synergistically enhance the friction modifier effect of this blend at the mixed lubrication regime, delaying the onset of boundary lubrication regime when the contact is lubricated by this mixture.

Impacts of engine lubrication oil-derived ash on soot oxidative reactivity on a catalytic gasoline particulate filter

Characterizing soot oxidation kinetics is crucial for understanding how gasoline particulate filters (GPFs) perform both in terms of filtration efficiency and pressure drop. The most common method for measuring soot oxidative reactivity is thermogravimetric analysis (TGA). Because TGA is an offline method, it may inaccurately predict how soot oxidizes on a GPF, especially if a catalytic washcoat is present that may enhance oxidation rates through surface interactions as the soot loads on the filter. In this work, a novel in-situ soot oxidative reactivity measurement method was developed. The method involved loading a catalytic GPF under high temperature conditions conducive to soot oxidation and measuring the filtration efficiency of 100 nm particles. A correlation was made between filtration efficiency and loaded soot mass on the filter to allow calculation of the soot oxidation rate. The method was evaluated in experiments using a 2.0 L gasoline direct injection (GDI) engine with three oils of varying additive packages, including an oil with a high zinc dialkyldithiophosphate (ZDDP) concentration, a non-additive, pure poly-alpha olefin (PAO) oil, and an oil with a high concentration of calcium sulfonate. Calculated specific soot oxidation rates ranged from ∼0.06–0.6 min−1 and showed strong dependence on GPF inlet gas temperature and lubrication oil additive type. The results clearly demonstrated a catalytic effect of calcium-containing ash particles. Reactivity of soot produced by the engine running with the high calcium containing lubrication oil was increased. Similarly, the results indicated that the catalytic washcoat on the filter increased soot oxidation rates on-filter, especially at low soot loading. Conversely, the ZDDP oil additive exhibited a reactivity inhibiting effect, resulting in lower soot oxidation rates. This work represents the first known in-situ soot oxidative reactivity measurements on a GPF and elucidates the effect of lubrication oil additives and catalytic washcoat on oxidation rate.

Effects of Transportation of IV Bags Containing Protein Formulations Via Hospital Pneumatic Tube System: Particle Characterization by Multiple Methods

In hospitals, often drug products in intravenous (IV) bags are transported via pneumatic tube systems (PTS). The goal of this study was to evaluate the effects of such transportation of protein products on particle formation in polyvinyl chloride (PVC) and polyolefin (PO) IV bags, containing either IV saline or dextrose. We studied intravenous immunoglobulin (IVIG) and a monoclonal antibody (mAb). Particles were quantified with flow imaging, light obscuration and nanoparticle tracking analysis. PTS transportation of IVIG caused large increases in protein particle concentrations, with much greater increases observed in saline than in dextrose. The increases were greater in IV solutions in PO than those in PVC bags. With the mAb, PTS transportation in saline caused increases in protein particle levels in PO bags, but not in PVC bags. Transportation in dextrose did not result in significant increases in mAb particle concentrations in IV bags made of either material. Overall, the results document that the PTS transportation can result in large increases in protein particles and that magnitude of these increases depends the protein itself, the bag material and the IV solution. The main conclusion is that protein products in IV solutions should not be transported in hospital PTS.

Effect of temperature on two-phase gas/oil relative permeability in unconsolidated sands

Thermal Enhanced Oil Recovery (TEOR) for heavy oil reservoirs involves the simultaneous flow of oil and steam, mimicking the gaseous phase with an elevation in the temperature. While implementing the TEOR process, reservoir performance prediction tools require the water/oil and gas/oil relative permeability data. Many studies reported the temperature effect on two-phase water/oil relative permeability despite knowing that steam or vapor is conventionally injected, mimicking the gaseous phase during heavy oil recovery. Thus, this requires the knowledge of temperature effect on two-phase gas/liquid relative permeability as well. However, limited studies are reported in the literature regarding the temperature dependency of relative permeability in gas/liquid systems; offer no census about its effects. The scarcity of such studies in the literature is due to the lack of systematic experimental studies and complications observed while conducting the higher temperature tests to mimic the thermal EOR. Hence, the objective of this study was to examine the temperature effect on two-phase gas/liquid relative permeability at varying temperatures from 64 to 132 °C using a systematic and reliable experimental process.In this study, Poly Alpha Olefin (PAO-100) was used as the oleic phase, deionized water as the immobile phase, and nitrogen gas as the displacing phase in a clean unconsolidated sandpack under the confining pressure around 1000 psi. Furthermore, Johnson-Neumann-Bossler (JBN) method was opted to interpret the two-phase gas/liquid relative permeability curves from the displacement data, i.e., cumulative oil production and pressure drop measured across the sandpack. The experimental observation suggests that irreducible water saturation and endpoint oil relative permeability are temperature independent. The residual oil saturation decreased with the increase in temperature and led to a higher endpoint relative permeability to gas. On the other hand, the oil relative permeability at equal saturation uplifted, suggesting the enhanced mobility of oil through pores with increasing temperature. On the other side, the gas relative permeability at equal saturation was temperature-insensitive other than at residual oil saturation. Also, the two-phase flow region increased with the rise in temperature as both the relative permeability curves shifted upwards, and the broader curve was observed. Hence, this study strongly suggests that the reservoir engineers or commercial reservoir simulators should account for the temperature effects on two-phase gas/oil relative permeability to efficiently predict heavy oil reservoir performance and management during the thermal enhanced oil recovery process (TEOR).

Producing Fluorine- and Lubricant-Free Flexible Pathogen- and Blood-Repellent Surfaces Using Polysiloxane-Based Hierarchical Structures.

High-touch surfaces are known to be a major route for the spread of pathogens in healthcare and public settings. Antimicrobial coatings have, therefore, garnered significant attention to help mitigate the transmission of infectious diseases via the surface route. Among antimicrobial coatings, pathogen-repellent surfaces provide unique advantages in terms of safety in public settings such as instant repellency, affordability, biocompatibility, and long-term stability. While there have been many advances in the fabrication of biorepellent surfaces in the past two decades, this area of research continues to suffer challenges in scalability, cost, compatibility with high-touch applications, and performance for pathogen repellency. These features are critical for high-touch surfaces to be used in public settings. Additionally, the environmental impact of manufacturing repellent surfaces remains a challenge, mainly due to the use of fluorinated coatings. Here, we present a flexible hierarchical coating with straightforward and cost-effective manufacturing without the use of fluorine or a lubricant. Hierarchical surfaces were prepared through the growth of polysiloxane nanostructures using n-propyltrichlorosilane (n-PTCS) on activated polyolefin (PO), followed by heat shrinking to induce microscale wrinkles. The developed coatings demonstrated repellency, with contact angles over 153° and sliding angles <1°. In assays mimicking touch, these hierarchical surfaces demonstrated a 97.5% reduction in transmission of Escherichia coli (E.coli), demonstrating their potential as antimicrobial coatings to mitigate the spread of infectious diseases. Additionally, the developed surfaces displayed a 93% reduction in blood staining after incubation with human whole blood, confirming repellent properties that reduce bacterial deposition.

Macromolecular Insights into the Altered Mechanical Deformation Mechanisms of Non-Polyolefin Contaminated Polyolefins

Current recycling technologies rarely achieve 100% pure plastic fractions from a single polymer type. Often, sorted bales marked as containing a single polymer type in fact contain small amounts of other polymers as contaminants. Inevitably, this will affect the properties of the recycled plastic. This work focuses on understanding the changes in tensile deformation mechanism and the related mechanical properties of the four dominant types of polyolefin (PO) (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP)), contaminated with three different non-polyolefin (NPO) polymers (polyamide-6 (PA-6), polyethylene terephthalate (PET), and polystyrene (PS)). Under the locally elevated stress state induced by the NPO phase, the weak interfacial adhesion typically provokes decohesion. The resulting microvoids, in turn, initiate shear yielding of the PO matrix. LLDPE, due to the linear structure and intercrystalline links, is well able to maintain high ductility when contaminated. LDPE shows deformation similar to the pure material, but with decreasing ductility as the amount of NPO increases. Addition of 20 wt% PA-6, PET, and PS causes a drop in strain at break of 79%, 63%, and 84%, respectively. The typical ductile necking of the high-crystalline HDPE and PP is strongly disturbed by the NPO phase, with a transition even to full brittle failure at high NPO concentration.

Preparation and tribological behaviors of magnesium silicate hydroxide-MoS2 nanoparticles as lubricant additive

The tribological properties of lubricating oil during service life largely depend on the properties of lubricant additives. Herein, we present a hydrothermal synthesis of magnesium silicate hydroxide (MSH)-MoS 2 nanocomposite and evaluate its tribological performances and repairing properties on worn surfaces as lubricant additive in poly-alpha-olefin (PAO). The microstructure of MSH-MoS 2 powders is MSH nanotubes surrounded by layered MoS 2 . The tribological test results show that the anti-friction performance and wear resistance of the friction pair were improved by 27.7% and 37.4%, respectively, after adding 1.0 wt% MSH-MoS 2 into PAO. More importantly, the worn volume of the friction disk can be repaired by 33.2% after sliding 5 h under the lubrication of PAO with MSH-MoS 2 . The superior tribological performance should be attributed to the formation of robust tribofilm with low shear strength, high hardness, strong resistance to plastic deformation, and high bonding strength on the sliding surface. • Rod-shaped magnesium silicate hydroxide-MoS 2 nanocomposites were synthesized. • The nanocomposites as additives show excellent anti-friction and anti-wear properties. • The nanocomposites show outstanding repairing properties on the worn surface. • A robust tribofilm with low shear strength and excellent mechanical properties was formed.

The reductive catalytic upcycling of polyolefin plastic waste

Plastics, and polyolefins (POs) in particular, revolutionized the everyday life, and after use the waste accumulation is raising severe environmental concerns fostering an intense the research towards more sustainable and profitable recycling routes.In this contribution, we focus the attention concerning recent advances on the reductive upgrading of POs promoted by heterogeneous catalysts, that is emerging as a valid alternative to pyrolysis since POs are transformed into valuable chemicals and fuels, allowing overcome the issue of elevated temperatures, as well as low selectivity and fast catalyst deactivation. As a matter of fact, the introduction of H2 gas in the reactor allows to carry out PO degradation in milder conditions coupled with a higher control on the produced hydrocarbons, depending on the employed catalyst and the reaction parameters. Two main processes have been so far developed: hydrogenolysis and hydrocracking, respectively leading to formation of diesel and gasoline. At a molecular level, their difference relies on the different typologies of catalysts, which are monofunctional metal catalysts in the former case (where both surface hydrides and surface alkyl species are formed and recombine each other), and bifunctional acid/metal catalysts in the latter (where, after a carbocation is formed by protonation, the reaction proceeds by isomerization and scission). Despite the conceptually simple and univocal definition of the two mechanisms, several catalytic processes have been developed in the last years, varying for both reaction conditions and obtained products, thus generating a quite complex scenario.Hereafter, the most significant results are reported to provide a consistent base for further progress.

A Comparison of Emerging Nonfluoropolymer-Based Coextruded PV Backsheets to Industry-Benchmark Technologies

As the photovoltaic (PV) industry is rapidly expanding around the world, there has been an increasing interest in extending the lifespan of PV modules. Concern has also emerged regarding the recyclability of modules and their component materials, including fluoropolymer-based backsheets. Laminated polyethylene-terephthalate (PET) core backsheets have traditionally been used in the PV industry, but new, coextruded polyolefin (PO) backsheets show promise as an improved alternative. Minimodule and coupon samples of seven different backsheets (made of layers including contemporary PET and fluoropolymers, novel PO, and polyamide materials) were run through hygrometric- or UV photolytic-accelerated aging to identify and better understand each material's degradation modes and the backsheets’ field reliability. In addition to the artificial aging, the natural weathering methods used in this article are described. The comprehensive set of chemical, mechanical, and structural characterizations at intermittent read points in this article is presented, including: visual appearance and color; gloss; mechanical tensile testing; I-V performance; electroluminescence (EL) imaging; dielectric breakdown; Fourier-transform infrared-chemical structure; X-ray-polymer structure; and differential scanning calorimetry-crystalline content. After 4000 h of aging, a strong correlation occurs between initial physical characteristics (mechanical tensile test) and operating performance (EL and I-V characteristics).

Synthesis and investigation of phosphorus-free ionic liquids as multifunctional lubricating additives.

Ionic liquids (ILs) have been extensively studied as lubricants or lubricant additives for two decades by virtue of their unique physical and chemical properties. Here, two phosphorus-free multifunctional protic ILs were synthesized by reacting oleic acid and a dimer acid with an alkyl aromatic amine. Both were completely miscible in various base fluids like mineral oil, polyether, synthetic ester, and polyalpha olefin. Furthermore, no corrosion towards copper strips was found for these additives due to the absence of phosphorus, halogen, and sulfur in their molecular structures. Tribological tests found that they could significantly improve the tribological performance of base oil in a wide range of test conditions. Additionally, due to the presence of an alkyl diphenylamine group, they could considerably enhance the oxidative stability of the base oil. Overall, the facile preparation approach, good solubility, low corrosion, and excellent tribological behavior and antioxidation property make them suitable as multifunctional additives in various lubricants.

RHEOLOGICAL PROPERTIES OF NANOCOMPOSITES FeCo@C-N BASED ON SUSPENSIONS IN PAO LIQUID PHASE

This paper will focus on rheological induced effect of FeCo/C-N nanocomposite particles in polyalphaolefin (PAO) as liquid medium for potential application in magnetorheological system. FeCo/C-N nanoparticles synthesized by frontal polymerization followed by thermolysis were characterised by XRD and TEM microscopy; the nanoparticles were finally dispersed at different content percentage in a PAO liquid medium to investigate the inherent rheological variation of the final suspension due to the presence of the filler loading. According to the XRD data, the diffraction peaks for FeCo are in good agreement with the standard diffraction pattern for the face-centered-cubic Fe-Co alloy. TEM images showed the formation of nanoparticles with an average size of 10 nm, and elemental analysis reveals the presence of a carbon-doped layer. Analysis of the suspension prepared showed that the loss modulus (G″) exceeds the storage one (G′) in the full range of the considered stress amplitude, supporting the conclusion that the presence of nanocomposite particles strongly enhance the viscoelastic behaviour of the base medium. According to the studies carried out in this work, the liquid medium exhibits a Newtonian flow over the entire spectrum of shear stresses, the maximum area of effective operation of the suspensions is up to 1 Hz. The relevant change in viscoelastic behavior of the employed liquid medium due to the presence of synthesized particle pave the way to the concrete application of this metallopolymer-based particles to design magnetorheological components or systems characterized by an inherent damping performance.

Stability Analysis of Fe3O4‐OA‐MWCNT Nanocomposite‐Based Nanofluid

The aim of this project is to fabricate a highly stable Fe3O4‐OA‐MWCNT composite and its colloidal suspension in polyalphaolefin (PAO) base fluid for heat transfer applications. The nanocomposite was produced in three mass ratios (0.5 : 1, 1 : 1, and 1.5 : 1) to explore the concentration effects on the stability of the nanocomposite. XRD analysis and FTIR spectroscopy were conducted to inspect the phase and composition of the synthesized nanocomposite. The crystallite sizes (3.75 nm, 7.74 nm, and 7.52 nm) and dislocation densities of each composite were calculated, and it was revealed that the samples with high concentration of iron oxide nanoparticles showed small defects in their lattices. Dispersion stability of ferrofluids was also examined by natural deposition method for 365 days. The ferrofluids displayed high stability for more than one year with no sign of sedimentation. Thermal conductivity of the nanofluid was also measured via. A transient plane source method and a linear trend with slight deviation were observed.

The Laboratory Performance of Asphalt Mixture with Thermoplastic Polyurethane (Tpu) and Amorphous Poly Alpha Olefin (Apao) Compound Modified Asphalt Binder

The Laboratory Performance of Asphalt Mixture with Thermoplastic Polyurethane (Tpu) and Amorphous Poly Alpha Olefin (Apao) Compound Modified Asphalt Binder

Rheological and Magnetic Properties of Stable Poly Alpha Olefins Based Ferrofluids with High Viscosity and Magnetization

Rheological and Magnetic Properties of Stable Poly Alpha Olefins Based Ferrofluids with High Viscosity and Magnetization

Preparation of self-lubricating porous alumina ceramics with PMMA /PAO6 microcapsules and their tribological properties

In this work, we showed that immersing polymethyl methacrylate (PMMA)/poly alpha olefins (PAO6) microcapsules into the porous matrix can improve the lubrication properties of porous alumina ceramics dramatically. PMMA/PAO6 microcapsules were synthesized by microemulsion polymerization, and the microcapsules were immersed in the porous alumina ceramic matrix by vacuum impregnation. The lubrication behaviors of the porous alumina ceramics with PMMA/PAO6 microcapsules have been investigated under different loads. As compared with the unprocessed porous alumina ceramics, the coefficient of friction (COF) of the porous ceramics impregnated with microcapsules could be reduced to 4% of that without microcapsules, and the wear rate could be reduced by two orders of magnitude. No obvious change of the COF was noticed for the matrices with different pore sizes. The good self-lubrication properties were achieved by releasing the PAO6 in the microcapsules during the friction process.

Ultralow friction polymer composites containing highly dispersed and thermally robust microcapsules

The heat-resisting property of microcapsules as additives directly determine the selection of matrix materials and the molding process of composite materials, which greatly affect the comprehensive properties of materials. In this research, thermally robust polyimide (PI) was used as shell material to synthesize microcapsules by solvent evaporation method, and the synthesized microcapsules were treated by soaking them in dopamine hydrochloride solution for improving their dispersion property in the matrix. The SEM and infrared spectra results showed that the PAO (Poly alpha olefins)@PI microcapsules with the dimeter of ~ 20 µm and the oil content of 60 wt% were successfully coated with polydopamine (PDA) shells. It was demonstrated that the strong electrostatic repulsion of PDA structure made the microcapsules better dispersed in the epoxy resin, so as to play a better role in lubrication, thus resulting in a COF (Coefficient of friction) decrease of composite from 0.108 to 0.038. The high temperature lubrication performance of composites was also investigated and the experimental results shown that the PAO@PI/PDA microcapsules could provide high lubrication performance with a low COF(0.074) at 190 ℃.

Palladated chitosan-halloysite bead as an efficient catalyst for hydrogenation of lubricants

Considering the synergism between chitosan and halloysite clay, herein, a novel catalytic composite is designed for promoting hydrogenation of poly alpha-olefin (PAO) oils under mild reaction condition. Briefly, naturally occurring chitosan and halloysite have been used for the formation of chitosan-halloysite beads. The beads were subsequently cross-linked and palladated. The reaction variables for the hydrogenation of PAO have been optimized. Moreover, the effect of chitosan: halloysite mass ratio on the performance of the catalyst has been investigated. It was an important factor that affects morphology, Pd average size and loading. It was also found that using 5 wt % catalyst with chitosan: halloysite mass ratio of 1:1 and hydrogen pressure of 8 bar at 130 °C, hydrogenated product was achieved in 98% yield. High recyclability and heterogeneous nature of the catalyst were also confirmed. Furthermore, comparative study confirmed positive effect of hybridization of halloysite and chitosan on the catalytic activity.

Ionic liquids as boundary additives in water-based and PAO lubricants

Ionic liquids have been widely discussed as potential lubricants, however, their properties make them also very good potential candidates as lubricant additives (e.g., friction modifiers and anti-wear). In this work, the tribological study of two ionic liquids (tributylmethylphosphonium dimethylphosphate (PP), and 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMP)) as lubricant additives has been performed on stainless steel (AISI 316L) exposed to polar (water-glycol) and non-polar (polyalphaolefin) based lubricants under boundary lubricating conditions. The performance of these ionic liquids as lubricant additives has been compared to a classical organic friction modifier (dodecanoic acid (C12)). The water-glycol lubricant formulated with the two ionic liquids showed friction values higher than the same base lubricant formulated with dodecanoic acid, however, opposite results were observed for polyalphaolefin (PAO). A detailed surface chemical analysis using X-ray photoelectron spectroscopy (XPS) revealed differences in the passive/tribofilm thickness and chemical composition of the stainless steel surface tested in all lubricants. In the case of the polar lubricant additivated with ionic liquids, the tribochemical reaction accompanied by a tribocorrosion process led to the formation of an unstable passive/tribofilm resulting in high friction and wear. However, in the absence of tribocorrosion process (polyalphaolefin base lubricant), the tribochemical reaction led to the formation of a stable passive/tribofilm resulting in low friction and wear. A detailed surface and subsurface investigation of the microstructure using scanning electron microscopy equipped with a focused ion beam (SEM-FIB) showed that high wear rates resulted in thicker recrystallization region under the wear track surface. Among all lubricant additives tested in this work, BMP in non-polar lubricant media showed the best tribological performance.