Reactor Pressure Research Articles

Formation and crystalline structure of spherulites from pea and high amylose maize starches.

Starch spherulite is a unique form of resistant starch characterized by a spherical structure with crystalline lamellae that are radially oriented and may find applications in delivery of nutrients and bioactives to the lower gastrointestinal tract. Formation of starch spherulites generally requires heating to a high temperature followed by quenching and long crystallization time. The objectives of this study were to gain a deeper understanding of the factors influencing spherulite formation from pea starch (PS) and high-amylose maize starch (HAMS) and investigate if spherulites could be formed by a slow cooling rate and determine the crystalline structure and morphology of the spherulites formed. Remarkably, spherulite was observed immediately after PS and HAMS (25 % solids) were heated to 180 °C and cooled to 10 °C at a cooling rate of 10 °C/min in a differential scanning calorimeter (DSC) pan. Increasing heating temperature degraded starches more but improved the morphological quality of spherulites. Spherulite was better formed at 25 % than 40 %. Both PS and HAMS formed spherulites with a predominant B-type crystalline pattern with 13-17 % crystallinity at ca. 10 % moisture content. PS displayed a single exothermic peak on cooling due to spherulite formation (recrystallization), whereas HAMS exhibited an extra peak due to the amylose-lipid complex formation. Spherulite production from HAMS and PS was successfully scaled up using a pressure reactor. This study provides a simplified approach for spherulite production, new potential utilization of PS and HAMS, and valuable insights for optimizing formation of starch spherulites.

Behavior of low alloy reactor pressure boundary steels in the loading range relevant for severe accidents and implications for material modeling in FE analyses

Behavior of low alloy reactor pressure boundary steels in the loading range relevant for severe accidents and implications for material modeling in FE analyses

Integrating machine learning to uncover homogeneous catalytic mechanisms in N‐vinyl‐pyrrolidone synthesis

AbstractCombining machine learning, density functional theory (DFT) calculation, and kinetic modeling offers significant advantages in studying reactions under complex conditions, enabling a detailed exploration of reaction mechanisms. Artificial neural network (ANN) models accurately predict and analyze the impact of reaction conditions, overcoming the limitations of traditional kinetic studies in complex systems. Specifically, the homogeneous catalytic reaction for synthesizing N‐vinylpyrrolidone from pyrrolidone and acetylene, which has stringent requirements, was selected. The ANN model effectively captured nonlinear relationships between residence time, moisture content, reaction temperature, catalyst concentration, reaction pressure, and catalyst preparation temperature. DFT calculations revealed the reaction pathways, leading to the development of a high‐precision predictive model. This approach not only uncovers potential reaction pathways and intermediates in complex reaction systems but also provides a new avenue for optimizing reaction conditions, resulting in more efficient catalyst design and process development in intricate reaction environments.

Forging-Submerged Arc Additive Hybrid Manufacturing of the Mn-Mo-Ni Component: In Situ Reheat Cycles Inducing the Homogenization of the HAZ Microstructure.

Forging additive hybrid manufacturing integrated the high efficiency of forging and the great flexibility of additive manufacturing, which has significant potential in the construction of reactor pressure vessels (RPVs). In the components, the heat-affected zone (HAZ, also called as bonding zone) between the forged substrate zone and the arc deposition zone was key to the final performance of the components. In this study, the Mn-Mo-Ni welding wire was deposited on the 16MnD5 substrate with a submerged arc heat source. The in situ reheat cycle effect of the submerged arc heat source on the microstructure and mechanical properties of the HAZ were studied. The results showed that the HAZ underwent four heat treatment processes, including two full austenitizing stages, one high-temperature stage, and continuous low-temperature tempering, which formed a homogenized microstructure in the HAZ and was mainly composed of tempered sorbite (Tempered-S). The HAZ microhardness is around 278.7 HV, which is about 150 HV lower than the microhardness only conducted by one thermal cycle. Furthermore, the effects of preheating the substrate and adjusting the heat inputs on the HAZ were studied. The results indicated that the clustered cementite was precipitated, which destroys the low-temperature impact toughness of the HAZ after preheating. A suitable heat input not only homogenized the microstructure within the HAZ but also promoted the transformation of grains into equiaxed grains. The -60 °C impact toughness of the HAZ was significantly increased from 96.7 J to 113 J.

Study on the Damping Performance of the Arrangement of Half-Bowl Spherical Structure Under Impact Velocity

During mine excavation, rock wall collapse can pose a safety risk to miners. Reasonably designed support equipment can prevent collapse and ensure a safe working environment. In this paper, a new half-bowl spherical rubber structure is introduced and modeled using Abaqus to study its damping ability under different impact energies. By comparing the support reaction forces and pressures of the A-S, R-S, and C-S structures, we find that the R-S structure, with a smaller number of half-bowl spheres, has superior energy absorption abilities and impact resistance. These findings support the designing and manufacturing of mining support equipment.

X-Ray Diffraction Line Broadening of Irradiated Zr-2.5Nb Alloys

The evolution of the mechanical properties of Zr-2.5Nb pressure tubing during irradiation is dependent on dislocation loop densities that are represented by the broadening of X-ray diffraction lines. Empirical models for the integral breadth of the diffraction peaks as a function of operating conditions have been developed to predict the mechanical properties of CANDU reactor pressure tubes as a function of fast neutron flux, time and temperature. Apart from predicting mechanical property changes based on integral breadth measurements, a new model has been developed to retrospectively deduce abnormal operating temperatures of ex-service pressure from the measured line broadening. The application of integral breadth measurements to assess mechanical properties and temperature variations in pressure tubes is described and discussed in terms of the implications for pressure tube integrity.

In situ etching of β-Ga2O3 using tert-butyl chloride in an MOCVD system

In this study, we investigate in situ etching of β-Ga2O3 in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2¯01-oriented and homoepitaxial (010)-oriented β-Ga2O3 films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2¯01 and homoepitaxial (010) β-Ga2O3 were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films.

Contributon-Informed Approach to RPV Irradiation Study Using Hybrid Shielding Methodology

An important aspect of pressurized water reactor (PWR) lifetime monitoring is supporting radiation shielding analyses which can quantify various in-core and out-core effects induced in reactor materials by varying neutron–gamma fields. A good understanding of such a radiation environment during normal and accidental operating conditions is required by plant regulators to ensure proper shielding of equipment and working personnel. The complex design of a typical PWR is posing a deep penetration shielding problem for which an elaborate simulation model is needed, not only in geometrical aspects but also in efficient computational algorithms for solving particle transport. This paper presents such a hybrid shielding approach of FW-CADIS for characterization of the reactor pressure vessel (RPV) irradiation using SCALE6.2.4 code package. A fairly detailed Monte Carlo model (MC) of typical reactor internals was developed to capture all important streaming paths of fast neutrons which will backscatter the biological shield and thus enhance RPV irradiation through the cavity region. Several spatial differencing and angular segmentation options of the discrete ordinates SN flux solution were compared in connection to a SN mesh size and were inspected by VisIt code. To optimize MC neutron transport toward the upper RPV head, which is a particularly problematic region for particle transport, a deterministic solution of discrete ordinates in forward/adjoint mode was convoluted in a so-called contributon flux, which proved to be useful for subsequent SN mesh refinement and variance reduction (VR) parameters preparation. The pseudo-particle flux of contributons comes from spatial channel theory which can locate spatial regions important for contributing to a shielding response.

Catalytic Performance of Sn-β Zeolites with Different Si/Al Ratios in the Conversion of Glucose to Lactic Acid.

Lactic acid is an important platform feedstock for synthesizing various chemicals. Lactic acid is normally converted from any sugar such as glucose, and Sn-β zeolite is an effective catalyst. In this study, β zeolite with different Si/Al ratios was prepared and characterized. Sn precursor is reacted with β zeolite by high-energy mixing and introduced into the framework of β zeolite to obtain Sn-β zeolite with different Si/Al ratios. The physicochemical properties of Sn-β zeolite were characterized by XRD, FTIR, N2 physical adsorption, UV Vis diffuse reflectance spectroscopy, and pyridine adsorption FTIR. The results showed that when the Si/Al molar ratio of β zeolite was less than 45, the skeleton load of Sn in β zeolite increased effectively with the decrease in aluminum content, and the Lewis acid and Brønsted acid site numbers could be improved. As the Si/Al ratio exceeded 45, the increase in Sn load in β zeolite slowed down, and the Lewis acid and Brønsted acid site numbers were decreased. The results from the catalytic conversion of glucose to lactic acid confirmed that the too high Si/Al ratio caused a decrease conversion rate. The highest performance of the prepared Sn-β zeolites with the highest catalytic efficiency had a glucose conversion rate of 96.69% and lactic acid yield of 39.42% within 7 h at 190 °C in a pressure reactor.

Engineering pyridinic-N-Co sites for enhanced CO2 hydrogenation to methanol

Regulation of hydrogenation capacity in cobalt-based catalysts is crucial for the effective conversion of CO2 into methanol. Herein, we developed a cobalt catalyst supported on nitrogen-doped carbon (viz., Co-N/C), specifically enriched with pyridinic N bonding to the cobalt sites. The hydrogenation capacity of the Co-N/C catalyst was carefully tuned by controlling the arrangement of pyridinic and pyrrolic N dopants through the ammonolysis treatment of the ZIF-67 precursor. The incorporation of pyridinic N significantly reduces electron localization around the cobalt centers, thereby minimizing unwanted hydrogenation to methane. The optimized Co-N/C catalyst, characterized by a predominance of pyridinic N, achieved a turnover frequency of 47.8h-1 for methanol production under 2MPa pressure and 180oC in a slurry reactor, surpassing the performance of a conventional Co/C catalyst featuring pyrrolic N by a factor of seven. Additionally, the Co-N/C catalyst exhibited excellent long-term stability, generating 70mmol of CH3OH and only 1.5mmol of CH4 over five cycles (totaling 30h). Both theoretical and experimental investigations revealed that pyridinic N has a greater affinity for bonding with Co compared to pyrrolic and graphitic N, and the pyridinic-N-cobalt serves as active sites for CO2 hydrogenation.

CFD simulation of injection point design for emergency core cooling system of ALLEGRO

The Emergency Core Cooling System (ECCS) is one of the critical safety systems in the Gas-cooled Fast Reactor (GFR) demonstrator ALLEGRO. The ECCS design must be improved to enhance fundamental safety functions, particularly in removing heat from the core under postulated plant conditions. In this paper, we focused on exploring the effect of coolant injection point on the performance of ECCS, for more efficient core cooling under Loss Of Coolant Accident (LOCA) scenarios. We initially performed a 1D primary system loop thermal hydraulic simulation to determine appropriate boundary conditions in case of a LOCA. These conditions were then applied to a CFD model of the ALLEGRO reactor pressure vessel, including injection nozzles at two positions. Transient 3D CFD simulations of LOCA in ALLEGRO were carried out using Fluent to determine location of the most effective emergency coolant injection point. We simulated the flow distribution through the core up to around 30 s after both small- and large-break LOCA events. The results suggest that bottom injection of the emergency coolant is preferred in an updated ECCS design. It provides a more uniform flow distribution across the core and therefore more advantageous than the previously suggested location in the downcomer.

Numerical investigation of an orthotropic finite elasticity problem using a constrained minimization theory to prevent material overlapping

We consider the problem of an elastic annular disk with uniform thickness in equilibrium in the absence of body force. The disk is fixed on its inner surface and compressed by a uniform pressure on its outer surface. The disk is made of a cylindrically orthotropic material that has a constitutive response that is stiffer in the radial direction than in the tangential direction. Material properties of this type are found in carbon fibers with radial microstructure and some kinds of wood.In the context of the classical linear elasticity theory, the solution of this problem predicts material overlapping for a large enough pressure, which is not physically acceptable. An approach to prevent this anomalous behavior consists of minimizing the total potential energy functional subject to the constraint that the determinant of the deformation gradient, J, be positive. We have used this approach to eliminate material overlapping, yielding solutions with J not close to one, which contradicts the basic assumption of infinitesimal strains upon which the classical linear theory is founded.In this work, we extend our investigation to the nonlinear elasticity theory. Necessary conditions for a deformation field to be a minimizer were found elsewhere. It includes a nonzero Lagrange multiplier that represents a reaction pressure to prevent material overlapping. We use a finite element formulation to find that, differently from its linearly elastic counterpart, the Lagrange multiplier field associated with the local injectivity constraint remains bounded. In addition, we obtain convergent sequences of approximate solutions of the disk problem formulated with both this constrained minimization theory and a compressible and orthotropic Mooney-Rivlin material. This material has certain growth conditions on the deformation field that prevents material overlapping in classical problems of mechanics. Both sequences yield convergent solutions that are in very good agreement with each other.

Process Simulation, Thermodynamic and System Optimization for the Low-Carbon Alcohols Production via Gasification of Second-Generation Biomass

Biomass-to-liquid fuels technology offers a promising method for high-value biomass conversion, addressing environmental toxicity and fossil fuel non-renewability. However, challenges such as low system efficiency and identifying efficiency losses persist. In this study, a comprehensive process model of a low-carbon alcohols production system via biomass gasification was developed, based on the first demonstration project in China. The innovation of this study lies in its detailed experimental validation, as the model simulation was performed using laboratory data and verified with pilot-scale platform data ensuring high accuracy. Additionally, the study conducted a thorough sensitivity analysis of system parameters, energy, and exergy assessments to find the proper operating conditions, including equivalent ratio, biomass type, and reactor temperature and pressure. The simulation results demonstrated an energy efficiency of 34.67% and an exergy efficiency of 31.24%. Through operating parameters and heat recovery measures, these efficiencies increased by 11.66% and 8%, respectively. This research not only obtains improved operating parameters for the pilot-scale platform but also provides actionable insights for enhancing the yields of target products and upgrading low-grade energy utilization. These findings offer valuable guidance for the commercialization of bio-syngas alcohols production systems, highlighting significant advancements in efficiency and system performance.

Cutting-edge advances in pressurized electrocatalytic reactors

Cutting-edge advances in pressurized electrocatalytic reactors

Fabrication of lignin-MOF derived spherical carbon supported NiCo-bimetallic catalysts for selective hydrogenolysis lignin derived ether.

The conversion of abundant lignin was of great significance for the utilization of biomass resources. In this study, lignin sulfonate (LS) was selected as a carbon-based support, which was successfully introduced into the NiCo-MOF structure. A series of lignin and MOF hybrid catalysts (NinCo-MOF-LS) with varying metal ratios of Ni and Co were synthesized via the hydrothermal method. Subsequently, the catalytic hydrogenolysis of lignin-derived dimers was conducted over a range of NinCo-MOF-LS, with the impact of calcination temperature and lignin addition in the catalysts taken into account. The selective conversion of benzyl phenyl ether (BPE) and other lignin dimers was achieved over the NinCo-MOF-LS catalyst with isopropanol serving as the hydrogen donor solvent in a nitrogen atmosphere. The Ni/Co metal ratio and calcination temperature were found to have a significant impact on the catalytic performance. Through a comprehensive investigation of various reaction parameters, including temperature, pressure, reaction time, and reaction solvent, it was determined that the catalyst exhibited excellent catalytic activity in the selective hydrogenolysis of BPE to cycloalkane and cyclohexanol. The optimal reaction conditions (240°C, 4h, 3MPaN2) were found to be conducive to the effective conversion of BPE into methylcyclohexane and cyclohexanol. The combination of lignin and metal-organic framework represented a novel approach to the utilization of lignin resources and the upgrading of biomass-derived chemicals.

Trends of Structure Degradation of VVER-1000 Reactor Pressure Vessel Steels Determining Their Performance at Lifetimes of over 60 Years

Trends of Structure Degradation of VVER-1000 Reactor Pressure Vessel Steels Determining Their Performance at Lifetimes of over 60 Years

Thermodiffusively-unstable lean premixed hydrogen flames: Length scale effects and turbulent burning regimes

This paper presents direct numerical simulations (DNS) of thermodiffusively-unstable lean premixed hydrogen flames in the canonical turbulent flame-in-a-box configuration. A range of reactant (pressure, temperature, and equivalence ratio) and turbulent (Karlovitz and Damköhler number) conditions are used to explore the effects of the small and large turbulent scales on local and global flame response. Turbulence-flame interactions are confirmed to be independent from integral length scale (or equivalently, from Damköhler number) for a fixed Karlovitz number. Furthermore, a recent model that predicts mean local flame speed as a function of an instability parameter and Karlovitz number is also demonstrated to be independent from integral length scale. This model thereby reduces turbulent flame speed modelling for thermodiffusively-unstable cases to predicting surface area enhancement. Flame surface area wrinkling is found to have good agreement with Damköhler’s small-scale limit. There is some scatter in the data, although this is comparable with similar experimental data, and the freely-propagating flame properties have a greater impact on the turbulent flame speed than the flame surface area. It is demonstrated that domain size can have an effect on flame surface area even if the integral length scale remains unchanged; the larger volume into which flame surface area can develop results in a higher turbulent flame speed. This is not accounted for in conventional algebraic models for turbulent flame speed. To investigate the influence of the fuel Lewis number Lef, an additional study is presented where Lef (alone) is artificially modified to span a range from 0.35 to 2. The results demonstrate that more flame surface area is generated for smaller Lef, but the difference for Lef≲1 is much smaller than that observed for Lef>1. A volume-filling-surface concept is used to argue that there is a limit to how much flame surface can develop in a given volume, and so there is only so much more flame surface can be induced by the thermodiffusive response; whereas the thermodiffusive response at high Lef is to reduce flame surface area. The agreement of the present data (and previous work) with Damköhler’s small-scale limit (even for low-to-moderate Karlovitz numbers) suggests that a distinction should be made between the small-scale limit and the distributed burning regime. Furthermore, it is argued that the distinction between large- and small-scale limits should be made based on Damköhler number. Consequently, the flamelet, thin reaction and distributed regimes should be distinguished by Karlovitz number (as usual), but the two latter regimes both have separate large- and small-scale regimes. Finally, implications for the turbulent premixed regime diagram are discussed, and a modified regime diagram is proposed.Novelty and significanceThis paper: confirms that turbulence-flame interactions at the flame scale are independent of integral length scale (at fixed Karlovitz number), as is the local flame speed model for thermodiffusively-unstable flames (Howarth et al., 2023); demonstrates potential domain size effect not accounted for in turbulent-flame models; flame surface wrinkling agrees with Damköhler’s small-scale limit for thermodiffusively-unstable flames in the thin reaction zone at low Damköhler number; and flame surface wrinkling increases slightly for low fuel Lewis numbers, but decreases significantly at high fuel Lewis numbers. There are significant consequences for the turbulent premixed regime diagram: distinction between Damköhler’s small-scale limit and distributed burning regime; separation of small- and large-scale limit by Damköhler number; application of the λ-flames concept to thin reaction zone; and exclusive use of Karlovitz and Damköhler number for regime classification and diagram axes.

Structure-Reactivity- and Modelling-Relationships during Thermal Annealing in Biomass Entrained-Flow Gasification: The Effect of Temperature and Residence Time

Biomass entrained-flow gasification enables the sustainable production of chemicals and liquid fuels. For reliable and accurate gasifier operation and design, the analysis of biomass char reactivity represents one of the key studies. Therefore, the annealing-induced char reactivity loss needs to be investigated for biogenic feedstocks from microscopic to reactor level. In the present work, the influence of pyrolysis temperature and particle residence time on solid digestate char reactivity and structure is studied. Several char types are prepared in a pressurized entrained-flow reactor between 1200 °C and 1600 °C with varying residence times between 0.4–2.4 s. Isothermal char reactivity in O2 and CO2 atmosphere is measured by TGA and reactivities are determined. Strong char deactivation between 1200 °C and 1400 °C resulted from severe heat treatment, especially toward the CO2 reaction. At 1600 °C, the influence of residence time becomes less relevant since all measured reactivities are comparably low. Experimental data are fitted to a coal deactivation model and verified for biogenic residues with very good agreement. The results are further corroborated by char structure analysis using FT-IR, XRD, Raman spectroscopy, SEM-EDX and ETV-ICP-OES. The decrease in char reactivity is mainly attributed to graphitization and the formation of aromatic ring structures. Char deactivation is further promoted by the loss of catalytic mineral matter and by high concentrations of inhibiting elements like phosphorus.

Computational Investigation of the High-Temperature Chemistry of Small Hydroxy Ethers: Methoxymethanol, Ethoxymethanol, and 2-Methoxyethanol.

In the search for alternative energy carriers that can replace conventional fossil fuels, sustainably produced oxygenated hydrocarbons represent a promising class of potential candidates. An illustrative member of this class of alternative biofuels are oxymethylene ethers (OMEs). This study makes a contribution to this objective by investigating hydroxy ethers, specifically methoxymethanol, ethoxymethanol, and 2-methoxyethanol. These bifunctional oxygenated molecules are relevant intermediates formed during the combustion of OMEs or via an equilibrium reaction in methanol and formaldehyde mixtures. The high-temperature chemistry of hydroxy ethers is examined, with a particular focus on the unimolecular reactions involving H atom migration and bond fission. Quantum chemical calculations are utilized to gain insights into these processes. The results include bond dissociation energies, one-dimensional representations of the potential energy surfaces along the reaction coordinate for the simulated reactions, thermodynamic properties, and reaction rate parameters, which were derived via established ab initio methods. A detailed account of the unimolecular decomposition reactions of methoxymethanol, ethoxymethanol, and 2-methoxyethanol is provided, including the predominant reaction rates and pressure dependencies. The BDEs are benchmarked against data from different literature sources. For ME, a direct comparison of BDEs and reaction constants is performed with the results of previous studies. The derived reaction parameters for all three hydroxy ethers are compared to the results obtained via theoretical methods for dimethoxymethane and diethoxymethane, which feature similar chemical structures. The high-temperature chemistry of methoxymethanol and ethoxymethanol shares similarities and is dominated by rapid H atom migrations, forming alcohol + formaldehyde. This reaction is geometrically constrained in 2-methoxyethanol and therefore bond fission reactions dominate. A brief systematic comparison of the bifunctional oxygenated structure of hydroxy ether with other fuel species, such as n-alkanes, ethers, and alcohols, was conducted. The findings of this study are supported by the results of published chemical kinetic models of 2-methoxyethanol, formaldehyde + methanol, and OME-2. This includes simulations of chemical kinetic mechanisms, which were updated with the newly derived reaction rates, and compared with associated experimental data from literature. These experiments are concentration measurements obtained from a jet-stirred reactor and laminar burning velocities measured in an atmospheric burner. The results are in reasonable agreement with the reported experiments and thus may be considered an update to the models. The updated reaction rate constants showed no observable impact on the ignition delay times of OME-2. However, they did result in a significant increase in the concentration of methoxymethanol as an intermediate. In conclusion, this study provides crucial insights into the high-temperature combustion properties of hydroxy ethers. The data presented is intended to enhance comprehension of the decomposition behavior of these bifunctional oxygenated species and to support the development of detailed chemical kinetic models for combustion applications.

Conversion of Penta‐Acetyl‐Xylitol to 3‐Acetoxymethylene‐Tetrahydrofuran by a Combined Hetero‐/Homogeneous Tandem Catalyst System

AbstractA tandem catalyst system comprised of trifluoromethanesulfonic (triflic acid, HOTf) or hafnium tetratriflate (Hf(OTf)4) and Ru/C in glacial acetic acid (HOAc) as the solvent at 200 °C and ∼ 7 MPa hydrogen pressure in a batch reactor converts penta‐acetyl‐xylitol ((2R,3R,4S)‐pentane‐1,2,3,4,5‐penta‐acetoxy‐pentane) or unprotected xylitol to 3‐acetoxymethylene‐tetrahydrofuran (3‐AMT) in up to 15% yield at full conversion. A comparative analysis by SEM‐EDS and XPS of the fresh commercial Ru/C catalyst versus catalyst reused and recovered after five cycles shows increasing aggregation of ruthenium to larger particles with a concomitant decrease in yield of 3‐AMT to 8%–9% for cycles four and five. 3‐AMT or its hydrolysis product 3‐hydroxymethyl‐tetrahydrofuran (3‐HMT) are valuable synthons for the preparation of agrochemicals, pharmaceuticals, and specialty polyurethanes and polyesters.