Rheological performance evaluation of asphalt modified with bio-based polymers

Fuel-based polymers, used as modifiers and additives in asphalt cement binders, improve the rheological performance of the base asphalt binders, therefore increase the resistance to pavement distresses. However, demand for polymers that are biodegradable, environmentally friendly, and cost effective is increasing. Soybean oil used as an alternative in place of soft and rubbery elastomers polybutadiene derived from crude oil was synthesized to bio-based polymers via chemical synthesis methods reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). In this study, bio-based polymers (PS-PAESO and PS-PAESO-Cl) with different styrene parameters were blended at a dosage of 3% by weight to a base asphalt binder by the solvent blending approach and three different shear blending methods. The objective of this study was to characterize the rheological properties of bio-based polymer modified asphalt blends by conducting dynamic shear rheometer (DSR), rolling thin film oven (RTFO), pressurized aging vessel (PAV), and bending beam rheometer (BBR) based on the Superpave performance graded asphalt binder specifications. The complex modulus (G*), phase angle (δ), mass losses, creep stiffness were determined to evaluate the rheological properties of the modified blends. Statistical analysis was conducted to evaluate the related factors that may influence the test results and to develop statistical modeling for predicting the bio-based polymers with appropriate styrene parameters that would optimize the rheological performance of the modified blends. Results from high temperature performance tests show that the addition of bio-based polymer (PS-PAESO and PS-PAESO-PS) used in this study increase the critical high temperature of the base binder that indicate an improvement on the resistance of rutting at high temperature. The similar results are observed from the master curves and the black diagrams which both exhibit stiffer behavior of the base asphalt at higher temperatures after modification, which indicates a rubber-elastic network establishment within the blends. Whereas, these bio-based polymers do not substantially improve the resistance to low temperature thermal cracking based on the critical low temperature results. Another finding is the use of bio-based polymers generally widened the continuous performance grade range of the base asphalt binder, which indicates that the bio-based polymers reduce the temperature susceptibility of the base asphalt binder. Furthermore, the statistical analysis on laboratory test results show no statistically significant difference between the three shear blending methods used in this study and no statistically significant difference between the polymer synthesis reaction durations. However, further statistical analysis by using block design on the shear blending methods and the polymer reaction durations shows there is statistically significant difference between the short and long reaction durations but no statistically significant difference between the shear blending methods. The finalized prediction models based on the response surface modeling present the same predicated styrene parameters in polymer to the test result analysis, which indicates that bio-based polymer with styrene parameters as lower molecular weight and lower styrene content are recommended for achieving higher critical high temperatures

Use of Bioadvantaged Materials for Use in Bituminous Modification

AbstractHistorically, the use of “green” materials around the world has been limited due to their higher production costs when compared to petrochemical derived materials. However, due to the recent volatility and increasing price of petroleum derivatives, there is a growing demand for the use of environmentally friendly materials. One of the most commonly used materials for bitumen modification are poly(styrene-block-butadiene-block-styrene) (SBS) type polymers. Recently, Iowa State University Chemical Engineering Department was able to synthetize thermoplastic elastomers using acrylated epoxidized soybean oil (AESO), a bioadvantaged replacement of butadiene, and styrene with the use of controlled radical polymerization techniques. Initial rheological tests conducted on the bitumen-polymer blends have shown that the biopolymers improve the complex shear modulus of the bitumen to a similar and even greater extent as the commercially available SBS polymers

Antibacterial, Antioxidant and Toxicological Properties of Artemisia annua Essential Oil

The essential oil of Artemisia annua grown in the Beijing area was extracted by hydrodistillation, and then its volatile components were analyzed by gas chromatography-mass spectrometry (GC-MS). The in vitro antioxidant activity of the Artemisia annua essential oil was determined by measuring the scavenging rate of DPPH and hydroxyl radicals, its antibacterial activity by using the agar diffusion method, and its toxicological properties by perfusing mice with different doses of the essential oil. The results showed that the extraction rate of the Artemisia annua essential oil was 1.04‰, with 332 essential oil components being identified by GC-MS analysis. Of these, 22 components accounted for 71.09% of the total volatiles, with relatively high contents of artemisinone (19.34%) and (+)-α-pinene (6.10%). The Artemisia annua essential oil exhibited good scavenging activities of the DPPH and hydroxyl radicals in a dose-dependent relationship. The highest scavenging rates of the DPPH and hydroxyl radicals were 40.03% and 92.97%, respectively, at an essential oil concentration of 10 mg/mL. The Artemisia annua essential oil significantly inhibited the growth of both Staphylococcus aureus and Escherichia coli, with inhibitory zones of 12.67±0.29 mm and 9.27±0.25 mm, respectively. The LD50 value of the Artemisia annua essential oil was 7491 mg/kg, indicating that it was not toxic. This study can provide a theoretical reference for the extraction and use of Artemisia annua and other Artemisia plants

Cold tolerance identification of nine Rosa L. materials and expression patterns of genes related to cold tolerance in Rosa hybrida

Members of the Rosa genus have a high ornamental value, but their cultivation area is limited by their sensitivity to cold temperatures. The aim of this study was to evaluate the cold tolerance of a range of Rosa materials, and then determine which genes were related to cold tolerance. Nine Rosa materials were subjected to a cold treatment. To identify genes related to cold tolerance, R. hybrida was treated at −15°C for 10 min, and leaves collected before and after this treatment were collected for RNA-Seq analyses. The transcript profiles of four DEGs (POD17, NDUFA9, PMA1, and b-Amy1) in R. hybrida were determined by qRT-PCR at 0 h, 1 h, 2 h, and 3 h at −15°C. Nine Rosa materials were subjected to a cold treatment, and the most cold-tolerant materials were identified as those that showed the lowest levels of electrolyte leakage and the best recovery after 30 d of growth. The most cold-tolerant materials were Rosa hybrida, Rosa rugosa ‘Pingyin 12’, and Rosa rugosa. In total, 204 significantly differentially expressed genes (DEGs) were identified, of which 88 were significantly up-regulated and 116 were significantly down-regulated under cold conditions. Gene Ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that the DEGs were enriched in 57 pathways, especially starch and sucrose metabolism, phenylpropane biosynthesis, MAPK signaling, fructose and mannose metabolism, and oxidative phosphorylation. By transcriptional analysis, PMA1, which was related to H+ ATPase activity, was continuously up-regulated, but the transcript levels of POD17, NDUFA9, and β-Amy1 fluctuated during the freezing treatment. This research uncovered scarce cold-resistant materials and layed the foundation for further research on the cold tolerance mechanism of Rosa plants and the breeding of cold-tolerant varieties

The BACH1 inhibitor ASP8731 inhibits inflammation and vaso-occlusion and induces fetal hemoglobin in sickle cell disease

In sickle cell disease (SCD), heme released during intravascular hemolysis promotes oxidative stress, inflammation, and vaso-occlusion. Conversely, free heme can also activate expression of antioxidant and globin genes. Heme binds to the transcription factor BACH1, which represses NRF2-mediated gene transcription. ASP8731, is a selective small molecule inhibitor of BACH1. We investigated the ability of ASP8731 to modulate pathways involved in SCD pathophysiology. In HepG2 liver cells, ASP8731 increased HMOX1 and FTH1 mRNA. In pulmonary endothelial cells, ASP8731 decreased VCAM1 mRNA in response to TNF-α and blocked a decrease in glutathione in response to hemin. Townes-SS mice were gavaged once per day for 4 weeks with ASP8731, hydroxyurea (HU) or vehicle. Both ASP8731 and HU inhibited heme-mediated microvascular stasis and in combination, ASP8731 significantly reduced microvascular stasis compared to HU alone. In Townes-SS mice, ASP8731 and HU markedly increased heme oxygenase-1 and decreased hepatic ICAM-1, NF-kB phospho-p65 protein expression in the liver, and white blood cell counts. In addition, ASP8731 increased gamma-globin expression and HbF+ cells (F-cells) as compared to vehicle-treated mice. In human erythroid differentiated CD34+ cells, ASP8731 increased HGB mRNA and increased the percentage of F-cells 2-fold in manner similar to HU. ASP8731 and HU when given together induced more HbF+ cells compared to either drug alone. In CD34+ cells from one donor that was non-responsive to HU, ASP8731 induced HbF+ cells ~2-fold. ASP8731 and HU also increased HBG and HBA, but not HBB mRNA in erythroid differentiated CD34+ cells derived from SCD patients. These data indicate that BACH1 may offer a new therapeutic target to treat SCD

Interleukin 18 function in atherosclerosis is mediated by the interleukin 18 receptor and the Na-Cl co-transporter

Interleukin-18 (IL18) participates in atherogenesis through several putative mechanisms1, 2. Interruption of IL18 action reduces atherosclerosis in mice3, 4. Here, we show that absence of the IL18 receptor (IL18r) does not affect atherosclerosis in apolipoprotein E–deficient (Apoe−/−) mice, nor does it affect IL18 cell surface binding to or signaling in endothelial cells. As identified initially by co-immunoprecipitation with IL18, we found that IL18 interacts with the Na-Cl co-transporter (NCC; also known as SLC12A3), a 12-transmembrane-domain ion transporter protein preferentially expressed in the kidney5. NCC is expressed in atherosclerotic lesions, where it colocalizes with IL18r. In Apoe−/− mice, combined deficiency of IL18r and NCC, but not single deficiency of either protein, protects mice from atherosclerosis. Peritoneal macrophages from Apoe−/− mice or from Apoe−/− mice lacking IL18r or NCC show IL18 binding and induction of cell signaling and cytokine and chemokine expression, but macrophages from Apoe−/− mice with combined deficiency of IL18r and NCC have a blunted response. An interaction between NCC and IL18r on macrophages was detected by co-immunoprecipitation. IL18 binds to the cell surface of NCC-transfected COS-7 cells, which do not express IL18r, and induces cell signaling and cytokine expression. This study identifies NCC as an IL18-binding protein that collaborates with IL18r in cell signaling, inflammatory molecule expression, and experimental atherogenesis

Performance evaluation of polymer modified asphalt binders utilizing soybean-derived materials

Polymer modified asphalt binders have been widely used in the construction of flexible pavement over the past few decades. Due to the economic and environmental concerns of using the traditional petroleum-derived polymers, there is a demand for developing sustainable alternatives that can replace the petroleum-derived polymers for use in asphalt pavements. Triglyceride molecules from vegetable oils have been considered as important renewable resources, which can be used as biomonomers and be polymerized into bioadvantaged polymers with similar properties to petroleum-derived monomers and polymers. In this research, non-food soybean oil is selected as a starting point to produce bioadvantaged polymers because it is the most affordable and abundant locally produced vegetable oil in the United States. The polymerized soybean oil has rubbery properties and can be used as an alternative to petroleum-derived butadiene in the styrenic block copolymers. In the laboratory, the bioadvantaged polymer poly(styrene-block-acrylated epoxidized soybean oil) (PS-PAESO) with various polystyrene molecular weights and contents are successfully produced through reversible addition-fragmentation chain transfer (RAFT) polymerization. Their modification effects in asphalt binders are investigated and evaluated via laboratory testing. The testing results are used in the response surface modeling (RSM) for the development of prediction models with the intent to optimize the formulation of the biopolymer for asphalt pavement applications in warm climate regions. The testing results show the great potential of using biopolymers as sustainable alternatives to commercial styrene-butadiene polymers as it improves the neat asphalt binder’s stiffness, elasticity, and rutting resistance at the same polymer dosage levels. The study on economic and environmental implications of biopolymers demonstrate that they are more cost-effective, environmentally friendly, and safer to produce than petroleum-derived styrenic polymers. Using biopolymers in asphalt modification has shown great success, however, there has been no literature so far discussing the use of acrylated epoxidized soybean oil (AESO) alone as an additive in asphalt binders, while many relevant researchers have conducted studies of using bio-based oil in asphalt binders. To study the modification effects of AESO in asphalt binders, laboratory produced AESO and commercially available AESO are used at various concentration levels in the neat asphalt binder, and their performances are evaluated through a comprehensive binder investigations including rotational viscosity, performance grading, rheological, aging susceptibility, high temperature storage stability testing, etc. The results reveal that AESO is able to be used as a modifier in asphalt performance modifications by softening the asphalt binder and reducing the binder’s stiffness. Furthermore, laboratory produced AESO performs superior to commercial AESO in terms of low temperature properties and fatigue life at the same dosage level without showing any separation problems. The findings also show that sufficient high dosage level of laboratory produced AESO can dramatically change the rheological properties of the neat asphalt binder with significant improvements on the resistance to fatigue damage and thermal cracking. Overall, the preliminary laboratory investigations on using soybean-derived polymers and additives in asphalt modifications have shown the feasibility of turning non-food soybean oil into more useful and valuable new materials. The results presented in this work may provide insights into the asphalt modifications using soybean-derived modifiers.</p

Rheological performance evaluation of asphalt modified with bio-based polymers

Fuel-based polymers, used as modifiers and additives in asphalt cement binders, improve the rheological performance of the base asphalt binders, therefore increase the resistance to pavement distresses. However, demand for polymers that are biodegradable, environmentally friendly, and cost effective is increasing. Soybean oil used as an alternative in place of soft and rubbery elastomers polybutadiene derived from crude oil was synthesized to bio-based polymers via chemical synthesis methods reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). In this study, bio-based polymers (PS-PAESO and PS-PAESO-Cl) with different styrene parameters were blended at a dosage of 3% by weight to a base asphalt binder by the solvent blending approach and three different shear blending methods. The objective of this study was to characterize the rheological properties of bio-based polymer modified asphalt blends by conducting dynamic shear rheometer (DSR), rolling thin film oven (RTFO), pressurized aging vessel (PAV), and bending beam rheometer (BBR) based on the Superpave performance graded asphalt binder specifications. The complex modulus (G*), phase angle (δ), mass losses, creep stiffness were determined to evaluate the rheological properties of the modified blends. Statistical analysis was conducted to evaluate the related factors that may influence the test results and to develop statistical modeling for predicting the bio-based polymers with appropriate styrene parameters that would optimize the rheological performance of the modified blends. Results from high temperature performance tests show that the addition of bio-based polymer (PS-PAESO and PS-PAESO-PS) used in this study increase the critical high temperature of the base binder that indicate an improvement on the resistance of rutting at high temperature. The similar results are observed from the master curves and the black diagrams which both exhibit stiffer behavior of the base asphalt at higher temperatures after modification, which indicates a rubber-elastic network establishment within the blends. Whereas, these bio-based polymers do not substantially improve the resistance to low temperature thermal cracking based on the critical low temperature results. Another finding is the use of bio-based polymers generally widened the continuous performance grade range of the base asphalt binder, which indicates that the bio-based polymers reduce the temperature susceptibility of the base asphalt binder. Furthermore, the statistical analysis on laboratory test results show no statistically significant difference between the three shear blending methods used in this study and no statistically significant difference between the polymer synthesis reaction durations. However, further statistical analysis by using block design on the shear blending methods and the polymer reaction durations shows there is statistically significant difference between the short and long reaction durations but no statistically significant difference between the shear blending methods. The finalized prediction models based on the response surface modeling present the same predicated styrene parameters in polymer to the test result analysis, which indicates that bio-based polymer with styrene parameters as lower molecular weight and lower styrene content are recommended for achieving higher critical high temperatures.</p