Structure Of Resin Research Articles

Synthesis of waterborne epoxy resin with diethanolamine-assisted succinimide for improving the strand integrity of polyimide filament

A water-soluble epoxy resin emulsion was synthesized by diethanolamine-assisted succinimide modified epoxy resin (DSEP) and used to reinforce the strand integrity of polyimide filament (PI). FTIR, XPS, and 1H NMR provide an evidence for the succinimide (SI) and diethanolamine (DEA) bonded onto the epoxy resin (EP) structure in the form of C-N-C. The DSEP emulsion shows high storage and dilution stability, with its particle size distribution and PDI of 118∼232 nm and 0.106∼0.638, respectively. Compared with DEA modified EP, DSEP exhibits better strand integrity for PI filament. The breaking strength of PI filament infiltrated by DSEP can reach 2.59 GPa, which is increased by 47.04% than that of PI filament, and is close to that of commercially available water-soluble polyimide resin (2.63 GPa). In addition, the fracture microstructure of PI filament further confirms that DSEP significantly reinforces the aggregation of PI filament. Importantly, there is no wire splitting phenomenon of DSEP reinforced PI filament after more than 200 times of friction. These benefit from the similar material groups of imide ring and benzene ring between DSEP and PI filament structure, as well as the strong hydrogen bonding interaction between them, as further confirmed by FTIR and SEM analysis.

Preparation and characterization of a melamine-urea-glyoxal resin and its modified soybean adhesive

Although polyamidoamine-epichlorohydrin (PAE)-modified soybean meal (SM) adhesives exhibit desired bond properties and technological applicability, their commercial application is still limited by the high cost of PAE resin. In this study, a formaldehyde-free crosslinking agent, melamine-urea-glyoxal (MUG) resin for SM adhesive, was developed based on investigations of the effects of melamine content and storage time on the structure and properties of MUG resin and MUG-modified SM adhesive. The test results confirmed that melamine could effectively copolymerize with glyoxal and urea to form an aldehyde-terminated MUG resin that was crosslinkable to soybean protein. The melamine content in MUG had important effects on the bond properties of the SM adhesive, attributed to the incorporation of aromatic triazine rings into the aliphatic urea-glyoxal chains and the greater reactivity and functionality of melamine than urea. However, the addition of melamine at more than 10% led to a shorter storage time of MUG resin and worse bond properties of MUG-modified SM adhesive. Owing to the further reactions of residual aldehyde and amino groups of MUG resin, the water resistance of the MUG-modified SM adhesive decreased with the storage time of the MUG resin. The allowable storage of the optimal MUG-10 resin was 3 weeks to ensure an acceptable bonding quality. Due to the much lower cost of MUG resin than PAE resin, it is beneficial for the wide commercial applications of formaldehyde-free SM adhesives in wood composites.

Projection printing of scaffolds with shape recovery capacity and simultaneously improved stiffness and toughness using an ultra-fast-curing poly(propylene fumarate)/hyperbranched additive resin

Projection micro-stereolithography (PμSL) is an effective technique to rapidly fabricate porous scaffolds with complex structures of photo-crosslinkable polymer resins, which normally contain a reactive diluent and a photo-initiator. In previous reports on 3D printing of poly(propylene fumarate) (PPF) scaffolds, diethyl fumarate (DEF) was unavoidably used as a reactive diluent in the PPF resin. Here we present a photo-crosslinkable resin composed of PPF and hyperbranched polyester acrylate (HPA), which has multiple carbon-carbon double bonds to participate in photo-crosslinking as a reactive diluent, and PμSL 3D fabrication of tissue-engineering scaffolds using this resin. The structure and viscoelastic behavior of uncrosslinked PPF/HPA, and the gel fraction, thermal and mechanical properties of photo-crosslinked PPF/HPA samples have been investigated, in comparison with those of PPF/DEF. Blending HPA with PPF was found to decrease the viscosity of PPF and to expedite the photo-crosslinking process, both of which are important in formation of PPF networks. In addition, HPA can effectively enhance the stiffness and toughness of the fabricated network simultaneously. In PμSL 3D fabrication, the cure depth (C d ) experiments proved that the PPF/HPA resin had an extremely low critical energy (E c ) of 2.1 mJ/cm 2 , leading to ultra-fast curing when exposed to ultraviolet (UV) light. Our rapid prototyping characteristics are evident under the premise of ensuring high precision. For the PPF/HPA resin, the exposure time per layer was only 0.1–2 s, which at least doubled the printing speed compared with the other 3D fabrication techniques. At high printing resolution of 50 µm, an ultra-fast printing speed of 18 cm/h was achieved by using the PPF/HPA resin, while the value for the PPF/DEF resin was only 3.6 cm/h. Benefited from the better crosslinked networks, the fabricated PPF/HPA scaffolds exhibited a lower shrinkage, higher stiffness and toughness, and better recovery capacity than their PPF/DEF counterparts, indicating their 4D printing characteristics.

Prediction of chain-growth polymerisation of vinyl ester resin structure at the carbon fibre interface

Carbon-fibre reinforced polymer composites play an important role in the aerospace, marine, construction and automotive transport industries due to their light weight and robust mechanical performance. The interface between the resin matrix and the carbon fibre surface is a critical zone, where poor interactions at this interface may give rise to a point of failure in the composite. It is therefore critical to develop structure/property relationships for these interfaces at the molecular level. This is challenging to achieve using experimental approaches alone, and molecular simulations can provide complementary data to achieve this goal. Although substantial progress has advanced such understanding of the interface based on epoxy resins, the analogous vinyl ester resin interface is relatively under-explored in terms of molecular simulation, despite their widespread utility in many applications. This may be due to the additional complexity inherent to the challenges of modelling chain-growth polymerisation at the interface. In this work, molecular simulations are used to polymerise a vinyl ester/styrene resin in the presence of a pristine fibre surface. The evolution of the polymer chains is characterised in terms of chain length, composition, and distance from the surface plane. The interfacial shear stress is calculated using a computational pull-out test, revealing poor interfacial integrity, consistent with recent experimental data. These findings provide a solid basis for future investigations to explore surface functionalisation strategies of the fibre surface to best tailor this critical interface in vinyl-ester resin carbon fibre composites.

Mechanism analysis of the immobilization of heavy metal ions with the water-soluble polymer: The influence of resin structure and the further adsorption of chelate

Polymer materials have become one of the potential materials for remediation of heavy metal (HM) contamination in water and soil. However, the specific advantages of polymers are rarely studied. Water-soluble thiourea formaldehyde resin (WTF) is one of the effective polymer amendments. Through leaching experiments, WTF can stabilize 93.0% of Cd2+ and 99.7% of Cu2+. The results of HM morphology analysis show that after adding WTF, most of the HMs have been transformed into a relatively stable state. For example, in the process of remediation of 6 mg/kg Cd contaminated soil, the proportion of acid-soluble Cd decreased from 56.5% to 12.8%, and the residual state increased from 13.5% to 45.4%. Compared with the resin-free structure, the three-dimensional structure of the resin plays an important role, but the efficiency of precipitation with HMs is doubled. According to the simulation of the adsorption process by Materials Studio, the characterization of the scanning electron microscope-energy dispersive instrument and the results of the adsorption experiment, in the solution, the precipitate formed by WTF and Cd2+ has multilayer adsorption of HMs, and can further adsorb HM by –OH. Soil enzyme activity experiments proved that the risk of secondary pollution by adding WTF is rare, and even WTF can achieve the effect of slow-release nitrogen fertilizer. In the WTF remediation process, the biological toxicity reduction of HMs is result from, on the one hand, the complexation of functional group of WTF; on the other hand, the resin structure of WTF; in addition, multi-layer adsorption and adsorption of end groups in the precipitation formed by WTF and HM. This work provides a theoretical basis for the potential capabilities of water-soluble resins and is beneficial to the design and development of subsequent amendments.

Synergistic effect of lignin and ethylene glycol crosslinked epoxy resin on enhancing thermal, mechanical and shape memory performance

Lignosulfonate (LS) was successfully introduced into the epoxy resin matrix with the aid of ethylene glycol (EG) dissolution. Both the rigid LS and soft EG segments were linked into the cross-linked network structure of epoxy resin via esterification of hydroxyl groups in LS and EG molecules with anhydride. The ultimate properties of cured samples were adjusted effectively by changing the proportion of LS and EG components. Curing reaction and kinetics were analyzed, by which the optimal curing process parameters were determined. Although thermal stability of LS itself was relatively lower than that of neat epoxy, the thermal performance was significantly enhanced for the modified sample of epoxy/LS0.5-EG0.5. At the same time, the flexural strength, flexural modulus and impact strength were found to be increased by 23.1, 35.7 and 15.1% respectively compared with the neat epoxy. In addition, the excellent shape memory behavior and improved mechanical stability with LS addition were exhibited by the cured LS-EG modified specimens. This work reveals that lignin can be used as an efficient functional additive to regulate thermal, mechanical and shape memory properties of epoxy resin.

Molecular Simulation of Resin and the Calculation of Molecular Bond Energy.

In this study, average structural characteristics of amber were researched and used as an example to establish the three-dimensional (3D) average structure of resin. Two coal samples containing solid amber were collected from Fushun and Hunchun in Northeast China, from which pure amber samples were separated and resin was extracted. Solid-state nuclear magnetic resonance (13C NMR) spectroscopy was used to obtain structural information of amber, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was performed on the resins to determine their molecular mass. The results of these studies revealed that the average structure of amber was dominated by cycloalkane, with a small amount of aromatic carbon, and there were almost no aliphatic chains in the structure. The molecular masses of the compounds in the resin were mainly in the range 99–750 Da, and the average molecular mass was ∼370 Da. To characterize the resin chemical structure, two 3D molecular models based on density functional theory were established taking amber as the example, and the relevant molecular bond energies were calculated. Based on these models, the interactions among the components in oil were studied, and the binding energies of the different molecules were calculated. In summary, in this study, amber was used as a medium to establish an accurate molecular model of resin and proved that compared to hydrocarbon compounds, resin molecules were more likely to interact with bitumen.

Spotlight onto surfactant\u2013steam\u2013bitumen interfacial behavior via molecular dynamics simulation

Heavy oil and bitumen play a vital role in the global energy supply, and to unlock such resources, thermal methods, e.g., steam injection, are applied. To improve the performance of these methods, different additives, such as air, solvents, and chemicals, can be used. As a subset of chemicals, surfactants are one of the potential additives for steam-based bitumen recovery methods. Molecular interactions between surfactant/steam/bitumen have not been addressed in the literature. This paper investigates molecular interactions between anionic surfactants, steam, and bitumen in high-temperature and high-pressure conditions. For this purpose, a real Athabasca oil sand composition is employed to assess the phase behavior of surfactant/steam/bitumen under in-situ steam-based bitumen recovery. Two different asphaltene architectures, archipelago and Island, are used to examine the effect of asphaltene type on bitumen's interfacial behavior. The influence of having sulfur heteroatoms in a resin structure and a benzene ring's effect in an anionic surfactant structure on surfactant–steam–bitumen interactions are investigated systematically. The outputs are supported by different analyses, including radial distribution functions (RDFs), mean squared displacement (MSD), radius of gyration, self-diffusion coefficient, solvent accessible surface area (SASA), interfacial thickness, and interaction energies. According to MD outputs, adding surfactant molecules to the steam phase improved the interaction energy between steam and bitumen. Moreover, surfactants can significantly improve steam emulsification capability by decreasing the interfacial tension (IFT) between bitumen and the steam phase. Asphaltene architecture has a considerable effect on the interfacial behavior in such systems. This study provides a better and more in-depth understanding of surfactant–steam–bitumen systems and spotlights the interactions between bitumen fractions and surfactant molecules under thermal recovery conditions.

Structure and properties of heat-resistant ABS resins innovated via MSAMI random copolymer

This work proposed an efficient method to synthesize acrylonitrile-butadiene-styrene (ABS) copolymer and α-Methylstyrene (α-MSt)/N-phenylmaleimide (NPMI)/Acrylonitrile (AN) (MSAMI) random copolymer via emulsion polymerization, aiming to combine the excellent heat resistance of MSAMI and numerous advantages of ABS resin including mechanical properties, processing and recyclability. The effects of the MSAMI content and α-MSt/AN ratio on the thermal performance, mechanical properties and the morphology of heat-resistant ABS were investigated by FITR, dynamic mechanical analyses (DMA), Vicat Softening Temperature (VST), Thermogravimetric Analysis (TGA) and Scanning Electron Microscope (SEM). As a result, the heat-resistant of ABS resin was obviously enhanced by MSAMI, and its glass transition temperature (Tg) could be extended with the increase of NPMI content. The Tg could reach 173°C when NPMI content was 20% at the same trend as the VST. Synthetically, the contradiction between the heat resistance and mechanical properties of ABS resin reached a good balance when the NPMI content was 15% and α-MSt/AN ratio was 69/31. In SEM, the fracture morphology of the heat-resistant ABS resin was gradually tended to be smooth with the increase of the NPMI content. Therefore, the MSAMI random copolymer was successful prepared, which provided insight for the synthesis of heat-resistant modifiers and promoted the potential application of heat-resistant modifiers in automobiles and aircraft.

A novel low-dielectric nanocomposite with hydrophobicity property: Fluorinated MOFs modified bismaleimide-triazine resin

A fluorine-functionalized zirconium-based metal organic framework (F4-UiO-66) was successfully synthesized via the reflux method, and the F4-UiO-66/BT nanocomposites of F4-UiO-66 modified bismaleimide-triazine resin (BT resin) were prepared. The effects of F4-UiO-66 on the crosslinking structure and properties of BT resin were evaluated for the first time. The investigations showed that the active H in F4-UiO-66 effectively catalyzed the self-polymerization of cyanate ester and promoted the formation of more rigid triazine rings which increased the initial storage modulus of nanocomposites. But the steric hindrance effect of F4-UiO-66 reduced the crosslinking density, which increased the free volume of nanocomposites. So, the dielectric constants of the nanocomposites were significantly reduced with the increase of F4-UiO-66 for the reduction of molecular polarization due to triazine rings and C–F bonds, and the decrease of polarization density caused by the nanopores and free volume. In addition, F4-UiO-66 was evenly dispersed in BT resin. On the basis of maintaining the thermal stability, the toughness and hydrophobic properties of nanocomposites were also enhanced. This study provided a novel approach for low-dielectric materials with hydrophobic property through the synergy between the nanopores and the C–F bonds.

Numerical simulation on cure behavior and optimization on cure cycle for encapsulation structure of epoxy resin

This paper aims at optimizing the cure cycle of specific encapsulation structures composed of E51 resin from room temperature cure cycle to medium-high “two-phase” cure cycle by means of combination of numerical simulation and experimental testing on the basis of experimentally obtained parameters of cure kinetics and mechanical properties for E51 epoxy resin. The numerical method was firstly adopted to simulate the effects of temperature magnitude and curing time in the first and second dwelling phase to internal temperature, degree of cure and strain of structure during curing to optimize the process parameter. Then the internal temperature and strain of the structure were real-time recorded using Fiber Bragg Grating (FBG) monitoring technique, and the corresponding results reveal the validity of numerical simulation, which demonstrates the reliability of the approach of optimizing the cure cycle using numerical simulation. Lastly, the properties of the casting body specimens of E51 resin manufactured with optimized and original cure cycle were compared, and the results show that the tensile strength, compressive yield strength, flexural strength and impact strength for the specimens manufactured with optimized cure cycle increase by 3.9%, 1.5%, 14.5% and 16.2% compared with the specimens manufactured with original cure cycle, respectively.

Improving the Intrinsic Thermal Conductivity of Epoxy Resin by Synergistic Effect between Rigid Groups and Hydrogen Bonds

AbstractAlthough introducing liquid crystal phase into epoxy resin for liquid crystal epoxy fabrication is one of the most conventional methods for improving the intrinsic thermal conductivity of epoxy resin, the complex molecular structure design and sophisticated synthesis process seriously limit its rapid expansion and further industrial application. Herein, the rigid groups of 4’4‐dihydroxybiphenyl were introduced into the main chain of epoxy resin by ring‐opening polymerization (ROP) to change the molecular structure of epoxy resin. The introduction of biphenyl groups enhances the “orderliness” of molecular structure and forms hydrogen bonds between molecules, which facilitates the transmission of phonons within the molecule. The intrinsic thermal conductivity of modified epoxy resin (MEP) reaches 0.29 W m−1 K−1. After adding the expanded graphite (EG) into the MEP matrix, the thermal conductivity of MEP/EG reaches 2.59 W m−1 K−1, which is 1133 % higher than that of EP. In addition, the MEP also has certain advantages in harsh environment, the |Z|0.01 Hz of MEP coating is higher than 1.4 times the value of EP coating after immersing in 3.5 wt% NaCl solution for ten days, which identified the excellent anticorrosion of MEP. The MEP prepared by this method can find great applications as heat conduction materials in harsh environment.

Molecular dynamics study on emulsified oil droplets with nonionic surfactants

The stability of heavy crude oil is closely related to the netlike structure formed by the aggregation of asphaltene and resin molecules inside the oil droplets, and the aggregation is too complex to accurately obtain the microstructure of these molecules experimentally. In this paper, molecular dynamics (MD) simulation was performed to investigate the structure of emulsified oil droplets on the molecular level. The simulation results showed: (i) The stacking structure of asphaltene and resin molecules form the netlike structure of the oil droplet, and it is also considered as the main reason of high stability and viscosity of heavy crude oil. (ii) When nonionic surfactants were introduced, some of them can adsorb to the surface of oil droplet and change its hydrophilicity; others can enter the interior of the oil droplets and destroy the stacking structure of asphaltene or resins inside the oil droplet. The decreased viscosity of emulsified heavy oil in the present of surfactants attributed to the increase of hydrophilicity on the oil drop surface and the damage of stacking structure inside the oil drops. (iii) the steered molecular dynamics (SMD) simulation proved that the mechanical properties of emulsified heavy oil droplet become easier to be destroyed with the increase of surfactant concentration, and it indicates that nonionic surfactant is beneficial to promote demulsification and viscosity reduction of crude oil.

Molecular engineering and modification of FCC slurry oil residue for improving ageing resistance of high quality paving asphalt

In the present work, a novel resin molecule based on fluid catalytic cracking (FCC) slurry oil residue was designed and prepared with aid of molecular simulation to improve its ageing resistance. The average molecular structure of resin was characterized with elemental analysis, Fourier-transform IR (FT-IR) spectroscopy, NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and designed resin was synthesized by attaching an additional propyl group to the as-received resin. The interactions of resins and asphaltene molecules were investigated via molecular simulation, UV-visible (UV-Vis) spectroscopy and atomic force microscopy (AFM). The results revealed that the equilibrium distance of designed resin-asphaltene dimer decreased from 0.42 nm to 0.38 nm while the lowest contact energy increased from 9.3 kcal/mol to 11.2 kcal/mol, indicating an improved stability of designed resin-asphaltene particles. The adsorption isotherm indicated that more modified resin molecules could be adsorbed by asphaltene than the original resin. Compared with original asphalt, less aggregation of asphaltene occurred in asphalt blended with modified slurry oil residue during ageing process, showing its greatly improved ageing resistance.

Synthesis of sawdust carbon supported nickel nanoparticles and its application in upgrading heavy crude oil

Nickel nanoparticles was supported on sawdust carbon via a hydrothermal method followed by calcination and used as a catalyst for heavy crude oil upgrading experiment. The performance of catalyst on catalytic pyrolysis of heavy crude oil was studied by laboratory experiments. The experimental results showed that under the reaction conditions of 350 °C, 30 min and 0.1 wt% catalyst, the viscosity reduction ratio of heavy crude oil was 74.50%, the viscosity can be reduced from 16,000 mPa·s (50 °C) to 4080 mPa·s, and the net efficiency of catalyst was 14.37%. Analysis results suggested that the viscosity reduction of heavy crude oil was caused by the destruction of structure of resin in the process of the catalytic pyrolysis reaction.

Performance and structures of urea-formaldehyde resins prepared with different formaldehyde solutions

Performance and structures of urea-formaldehyde resins prepared with different formaldehyde solutions

Novel environment friendly olive pomace-cyclohexanone formaldehyde composite resin

PurposeCyclohexanone-formaldehyde resin (CFR) was in situ modified with olive pomace (OP) in the presence of sodium hydroxide. The purpose of this study is to produce eco-friendly OP modified cyclohexanone composite resins (OPCFCR) with a one-step method that has higher condensation reaction temperature than CFR. The water absorption properties, gloss value and cross-cut adhesion properties of the product were investigated.Design/methodology/approachCyclohexanone, formalin (37% aqueous solution) and tannin were mixed and 20% aqueous NaOH solution was added to produce the resin. OP has environmentally friendly bio-based lignin, cellulose and phenolic compounds and the OP structure has been incorporated into the structure of the CFR resin during the in situ modification, such as resole resin and polysaccharide. The weights of pomace were used as 5% and 10% of the weight of cyclohexanone in cyclohexanone-formaldehyde composite resins, respectively.FindingsThere is an improvement in the properties of the OPCFCR produced from an agricultural waste that is very abundant in Gulf of Edremit region of Balikesir. The OPCFCRs were soluble in common organic solvents. The product OPCFCR has a dark red-brown color.Research limitations/implicationsThe reaction mixture must be stirred continuously. Subsequently, 37% formalin was added dropwise in total while refluxing. The amount of aqueous NaOH solution is limited as the formed resin may become insoluble in common organic solvents. At the end of the reaction, a water-insoluble resin is obtained.Practical implicationsThis study provides the application of ketonic resins. The OPCFCR containing phenolic groups may also promote the adhesive strength of a coating.Social implicationsThese resins may be used for the preparation of adhesive. OP, with a large amount of catechol groups, was considered for reducing the formaldehyde emission level on the adhesive system.Originality/valueOPCFCR has been synthesized in the presence of a base catalyst. Environmental and ecological concerns have increased the attention paid by chemical industry to renewable raw materials.

Improving interfacial strength of epoxy composites by constructing “palm‐tree”‐like structure on carbon fiber

AbstractModified graphene oxide (GO)/carbon fiber (CF)/epoxy (EP) composites are prepared by combining grafting and sizing methods. The effects of different molecular chain lengths of poly(oxypropylene)amines on the surface grafting of GO, as well as the interfacial structure and properties of CF and EP resin after sizing, were investigated. The “palm‐tree”‐like structure interfacial enhancement theory was innovatively proposed. The characterization results showed that the short‐chain poly(oxypropylene)amines modified GO (D400‐GO) had a good effect on the interfacial properties of CF and EP resin. When the content of D400‐GO was 0.20 wt%, the interfacial shear strength was as high as 70.56 MPa, which was 37% higher than the virgin CF. In this article, a new theoretical model is proposed for multiscale interfacial enhancement.

Effect of functional groups of magnolol-based cyclic phosphonate on structure and properties of flame retardant epoxy resin

Functional group of a flame retardant may change performance and reaction mechanism of polymers to some extent. In this paper, magnolol-based cyclic phosphonates with double bond (DPDO) and epoxy group (EDPDO) were synthesized, and used in epoxy resin (EP). The EP/DPDO have better flame retardancy than that of EP/EDPDO in the UL-94 and LOI tests, while the pHRR of the latter decreases more that of the former in cone calorimetry test. Moreover, EP/EDPDO has higher glass transition temperature. Both DPDO and EDPDO do not deteriorate the mechanical properties and transparence of EP greatly. It is shown that the mechanism of the two is different. The DPDO is free in the resin, while the EDPDO is fixed in the framework of EP, therefore DPDO works in the gas and condensed phase, and EDPDO remains in the condensed phase. This work provides a simple solution to regulate the structure and performance of EP materials.

Microvascular anatomy of the non-lobulated liver of adult Xenopus laevis: A scanning electron microscopic study of vascular casts.

The microvascular anatomy of the non‐lobulated liver of adult Xenopus laevis was studied by scanning electron microscopy of vascular corrosion casts. Hepatic portal veins and hepatic arteries entered hepatic lobes at the hiluses, hepatic veins left at these sites. Intraparenchymal, hepatic portal veins branched up to 10 times before terminal portal venules supplied liver sinusoids. Hepatic arteries closely followed portal vessels. Arteriolar side branches formed anastomoses with close by portal venules (arteriolar‐portal anastomoses; APAs), liver sinusoids (arteriolar‐sinusoidal anastomoses; ASAs), and peribiliary plexus vessels. Distally, hepatic arteries anastomosed with terminal portal venules having >100 μm in diameter. Liver sinusoids formed a dense three‐dimensional network displaying signs of non‐sprouting and sprouting angiogenesis evidenced by “holes” and blind ending tapering cast vascular structures (sprouts), respectively. Sinusoids drained via efferent hepatic veins. Right and left hepatic veins drained into the posterior caval vein. Locally, a dense honeycomb‐like 3D‐meshwork of resin structures was found around terminal portal venules and hepatic arteries. These networks were fed by hepatic arterioles and drained into adjacent terminal portal venules. As their morphologies differed significantly from sinusoids and they were found at sites where diffuse lymphoid tissue is described, we are convinced that they represent the vasculature of diffuse lymphoid tissue areas. Frequencies and diameter ratios of hepatic portal venules versus hepatic arterioles anastomosing with the former (APAs) implicate that the arterial supply contributes to the oxygenation of parenchymal and stromal cells rather than to a significant increase in blood flow towards hepatic sinusoids.