Average Pore Area Research Articles

Variation of nanoparticles in pickering emulsion optimize the physical, control-release and sustained antioxidant properties of hydroxypropyl methylcellulose based microporous film.

The proper encapsulation of liposoluble tea polyphenols (LTP) is expected to better protect oil system. Chitosan hydrochloride-carboxymethyl starch (CHC-CMS) nanoparticles-based Pickering emulsions and hydroxypropyl methylcellulose/sodium citrate (HPMC/SC) microporous film were combined to embed and control-release LTP. With the CHC:CMS ratio varied from 1:0.5 to 1:2, the average size of LTP droplets of Pickering emulsion increased from 6.0μm to 8.5μm, the average area of cross-sectional pores of functional films increased from 1.78μm2 to 3.22μm2, the water vapor permeability of functional films increased from 2.02×10-10 to 2.44×10-10g·mm-1·s-1·Pa-1, the light transmittance and the quantity of cross-sectional pores decreased. The release ratio first increased (<24days) and then remained stable (≥24days), the stable release ratio was positively correlated with the size of the emulsion droplets in the emulsion and the size of cross-sectional pores in the film. Functional films had better protection effect on oil than free LTP during later storage period (≥32days), among which, functional film containing CHC-CMS 1:2 showed optimal sustained antioxidant effect on Perilla seed oil, which corresponded well to its highest stable release ratio.

Enhanced dewatering performance of vitrinite and inertinite: synergistic effect of flocculants and surfactants

ABSTRACT The moisture of coal has a significant impact on its marketing and conversion. Using chemical reagents to reduce coal moisture has gained popularity due to their efficiency and low investment. Flocculants and surfactants are common filter aids that can effectively reduce product moisture and increase the filtration rate. However, there are almost no studies on the effect of their synergism on dewatering. Hence, the synergistic effect between flocculants and surfactants on the dewatering behavior of macerals, the main components in fine clean coal, was investigated in this paper. The results showed that the synergistic effect of flocculants and surfactants significantly reduced the moisture content of the maceral cake. The combination of nonionic polyacrylamide (NPAM) and dodecyl trimethyl ammonium bromide (DTAB) was the best combination agent. Compared to vitrinite, this combination agent more significantly reduced the moisture content of the inertinite cake. The combination agents formed new forms of adsorption, improved particle wettability, promoted particle agglomeration and increased the cake average pore size and pore area. However, the new form may have led to an increase in the dosage of the agent.

Unravelling the nexus between structure, texture, and acoustic traits of fried chicken nuggets

SummaryTexture is a multi‐parameter attribute and one of the prime quality attributes of fried products. This study explored the nexus between microstructure and texture of fried breaded chicken nuggets. Chicken nuggets were deep‐fat fried (2, 4, 6, and 8 min) in canola oil at different frying temperature (170, 180, and 190 °C). Microstructure and texture of fried samples were assessed by scanning electron microscopy (SEM) and acoustic‐mechanical texture analyser, respectively. Maximum force (Fmax), number of force peaks (NFP), area under force‐deformation plots (FA), sound pressure level (SPL), number of sound peaks (AUX), and area under amplitude‐time curves (SA) were used to describe the textural parameters. Microstructural indices (porosity, number of pores, average pore area, polydispersity index, and average shape factor) were estimated from the SEM images. Results revealed that, both the frying time and temperature were positively correlated with the mechanical (Fmax: 25–55 N, NFP: 05–74 N, FA: 6500–15 000 N.sec) and acoustic (SPL: 88–97 dB, AUX: 650–810 dB, SA: 380–405 dB.sec) parameters. Frying time and temperature significantly (P &lt; 0.05) impacted the formation of micropores in fried chicken nuggets. Crust microporosity showed strong positive correlations (r = 0.82) with the AUX value. The NFP, SPL, and SA of the fried nuggets were significantly (P &lt; 0.05) impacted by the crust microporosity. Crust porosity (10–30%), number of pores (8–400), average pore area (10–4000 μm2), polydispersity index (0.05–0.2), and average shape factor (0.8–1.1) of fried nuggets were significantly (P &lt; 0.05) influenced by both the frying time and temperature. Findings from this study would be useful in quality improvement and process monitoring including modelling of coated fried products.

Influence of hydrocolloids and flours on acoustic‐mechanical and microstructural properties of battered deep‐fat fried meat

SummaryThis study investigated the influence of hydrocolloid–flour mixtures on textural, structural, oil absorption and optical characteristics of batter‐coated fried meat. The batter coatings were formulated with corn, wheat and rice flours along with different hydrocolloids (methylcellulose, carboxyl methylcellulose, xanthan gum, locust bean gum, gum arabic). Textural and structural properties were assessed by acoustic‐mechanical and scanning electron microscopy, respectively. Results showed that the addition of hydrocolloids improved crispiness and reduced oil content in fried products. Comparative performances of the hydrocolloids in improving crispiness were in decreasing order as gum arabic &gt; locust bean &gt; xanthan gum &gt; carboxyl methylcellulose &gt; methylcellulose. Textural properties of the hydrocolloids were interwoven with the flour type, where corn flour demonstrating better crispiness than wheat and rice flours. The crispiness of hydrocolloids added batter increased up to seven times than the control samples. The hydrocolloids were found to significantly influence (P ≤ 0.05) the appearance of battered meat formulated with corn and wheat flours. Hydrocolloids showed prominent effect on wheat flour‐based batter in terms of average pore area, whereas highest impact on corn flour regarding the number of pores formed.

A field study of pore-network systems on the tight shale gas formation through adsorption-desorption technique and mercury intrusion capillary porosimeter: Percolation theory and simulations

Properly identifying microscopic pore structure properties of shale reservoirs is essential for developing efficient extraction techniques of shale hydrocarbons. To understand the unique and complex pore network of the Northern Guizhou shale reservoir, shale samples from the Wufeng-longmaxi Formation were investigated using different analytical techniques, X-Ray Diffractometry, low-pressure nitrogen gas adsorption-desorption isotherms, and Mercury intrusion capillary porosimeter. Results indicate that the Wufeng-longmaxi formation is mainly composed of a high quantity of quartz ranging from 0.6 % to 64.1 % and an average extent of 55.825 %, the lowest amount of potassium feldspar ranging from 0.6 % to 2.2 % and an average extent of 1.45 % with Total organic contents ranging from 3.672 to 5.209 %. Similarly, the BJH adsorption techniques for pore volume and area were investigated. The results indicate the dominance of the mesopore with pore size ranging from 2.03 nm to 40nm, average pore volume of 0.073715 m3/g, and average pore area of 13.0324 m2/g. The pore throat distributions from MICP showed drain pressure and median pore throat radius ranging from 0.47 to 13.79 MPa and 0.05–0.08 μm, respectively. Suggested complementary experimental techniques reveal the connectivity of pore networks of the Wufeng-longmaxi Formation shale reservoir, which shows a high production potential of hydrocarbons. The findings of this study can provide a valuable understanding of fluid transport properties and storage space of shale gas that can help decision-makers as they set exploration initiatives for shale gas reservoirs.

Comparative Analysis of the Ultrastructure, Bubble Pores, and Composition of Eggshells of Dwarf Layer-White and Guinea Fowl.

The decrease in eggshell quality seriously affects production efficiency. Guinea fowl (GF) eggs possess strong eggshells because of their unique crystal structure, and few systematic studies have compared laying hen and GF eggs. Sixty eggs were collected from both 40-week-old Dwarf Layer-White (DWL-White) laying hens and GF, and the eggshell quality, ultrastructure, bubble pores, and composition were measured. The results showed that the DWL-White eggs had a higher egg weight and a lower eggshell strength, strength per unit weight, thickness, and ratio than the GF eggs (p < 0.01). There were differences in the mammillary layer thickness ratio, the effective layer thickness ratio, the quantity of bubble pores (QBPs), the ratio of the sum of the area of bubble pores to the area of the eggshell in each image (ARBE), and the average area of bubble pores (AABPs) between the DWL-White and GF eggs (p < 0.01). The composition analysis demonstrated that there were differences in the organic matter, inorganic matter, calcium, and phosphorus between the DWL-White and GF eggs (p < 0.01). There were positive associations between the mammillary knob number in the image and the QBPs and ARBE and a negative correlation with the AABPs in the DWL-White eggs (p < 0.01). This study observed distinctions that offer new insights into enhancing eggshell quality.

The U-net-based ice pore parameter extraction method for establishing the SAW icing sensing mechanism

The porous ice layer formed upon the SAW (surface acoustic wave) propagation path will produce transient acoustic attenuation, and a new icing sensing method can be constructed based on this feature. Obtaining the pore characteristics of an ice layer is a prerequisite and basis for deriving the sensing mechanism of SAW icing. Employing the U-net network, a segmentation model of frozen pores is developed by collecting frozen images and calibrating sample data sets for training in this work. The MIOU and the MPA of the model reach 92.16 % and 95.15 % respectively. Then, the watershed algorithm and post-processing were used to accurately obtain the pore characteristic parameters (porosity, pore number, and average pore area) of the ice layer. On this basis, applying the Biot's theory for two-phase porous media, a theoretical model of the SAW icing sensing mechanism was established, and the acoustic sensing response under different icing types was theoretically simulated. To prove the accuracy of the theoretical simulation, a SAW sensor using a waveguide structure of SU-8/ST-90 °X quartz operating at 80 MHz was constructed and evaluated experimentally. The results demonstrate that the acoustic sensing responses of different ice types are completely consistent with the theoretical results. This fully verifies the accuracy of the ice pore parameters extracted in this work and also confirms the feasibility of using pore microscopic information to achieve ice detection and ice type discrimination.

Effect of Travel Speed on the Properties of 5087 Aluminum Alloy Walls Produced by Wire and Arc Additive Manufacturing

An innovative Wire and Arc Additive Manufacturing combines the well-studied process of arc welding with direct energy deposition. Effect of travel speed 5.0 and 7.5 mm/s on the microstructure and mechanical properties of 5087 aluminum alloy was investigated. Five thousand eighty-three aluminum alloy was used as a substrate material and 5087 aluminum alloy was utilized as a filler material for the walls fabrication. The presence of pores reducing the strength of the overlay weld metal was detected on both overlay welds. The lower welding speed (5 mm/s) resulted in the smaller amount of porosity in comparison to higher welding speed (7.5 mm/s). Average pore area of wall No. 1 was 0.66% and wall No. 2 was 1.13%. It was found that higher welding speed affected the wall width and overlay weld bead geometry. Increase in welding speed led to a narrowing of wall width from 10.23 to 8.44 mm. The microstructure of weld metal matrix consisted of a α-Al substitution solid solution. The tensile strength of parallel to welding direction removed samples exceeded the tensile strength of perpendicular removed samples. It is a result of the cohesion of the layers in the overlay welding direction compared to the non-uniformity of the layers in the perpendicular direction. Furthermore, the tensile strength was higher in the case of travel speed of 5 mm/s in comparison to that of 7.5 mm/s.

Starch sources and their influence on extrusion parameters, kibble characteristics and palatability of dog diets

This study aimed to evaluate the effects of different starch sources on the extrusion process, kibble characteristics and diet palatability for dogs. Seven diets with corn, brown rice, sorghum, potato starch, sweet potato flour, chickpea and pea as the only starch source were evaluated. The dietary inclusion of the starch sources varied between 330.13 and 643.84 g/kg to provide similar starch concentrations in all diets (around 300 g/kg). The conditioning temperature and the volume of water added to the preconditioner during the processing of the diets were measured, and the extruder variables evaluated were knife speed, feed rate, screw speed, amperage and productivity. For the physical characteristics of kibbles, density, size, expansion index and hardness were measured. Porosity variables evaluated were total pore area, average pore area and number of pores. Diet palatability was evaluated in 16 dogs. Six paired palatability tests were performed, in which all diets were compared to the corn diet, with two consecutive days per test, totalling 32 repetitions (16 dogs × 2 days/test). Diets with tubers presented lower kibble density and higher size, expansion index and hardness than the diets with cereals and pulses (p < 0.001). Diets with tubers had more pores than pulses (p < 0.001). The inclusion of pea results in kibbles that were less expanded and with fewer pores (p < 0.001). Dogs preferred all diets compared with the corn-based diet (p < 0.001), except for the sweet potato diet. The dietary inclusion of tubers as starch sources results in higher kibble expansion, size, hardness, porosity and lower density. The inclusion of pea results in kibbles that are less expanded and with a lower number of pores. The diet’s moisture content and texture affect diet palatability in dogs.

Controlling C–C coupling reactivity through pore shape engineering of B-doped graphyne family

Graphyne is an interesting carbon allotrope characterized by sp-sp2 hybridized carbon bonds, which allow for structure variability. Though there are studies evaluating the electrical and mechanical properties of various structures, studies utilizing its structural variety toward catalyst applications are minor. In electrocatalytic CO2 reduction reactions (CRR), producing valuable C2+ products, such as C2H4 or C2H5OH, under mild conditions is still challenging. The bottleneck has been assigned to the carbon-carbon (C–C) coupling reaction, such as 2*CO → *OCCO. In this reaction, one requires strong binding to the catalyst to enhance neighboring CO concentration, but at the same time, one needs to have low C–C coupling barriers making the OC-CO bond. Following our previous study, which showed B-doped γ-graphyne can be a catalyst for ethanol production, we conducted theoretical investigations on a range of B-doped graphyne families using density functional theory. Out of the 15 different structures studied, four, 4,12,2-, sR-, γ-, and 6,6,12-graphynes, show promising potential for CRR. B-doped 4,12,2-graphyne, with small square and rectangular pores, had a very low C–C coupling barrier of 0.34 eV with strong 2*CO adsorption (−2.5 eV). Furthermore, our research revealed a correlation between the heat of reaction (2*CO → *OCCO) and the average pore area around the acetylenic linker reaction site. Smaller pores give a favorable orientation of two CO molecules, resulting in low reaction barriers.

Study on the storage characteristics of steamed rice bread samples during various storage temperature

The storage quality of steamed rice bread (SRB) is crucial to its industrial production. This paper explored the changes in the texture, moisture content, volatile compounds, and microstructure of SRB during storage at room temperature (RT) and refrigerated temperature (FT) before and after re-steaming. During storage, SRB's moisture and springiness decreased over time, while the hardness increased. Seven significantly increased off-flavor volatile compounds were characterized by gas chromatography-ion mobility spectrometer (GC-IMS) analysis. The microstructure parameters (porosity, EqDiameter, length and width of pores, average pores area and average volume of pores) of SRB based on X-ray computed tomography (CT) showed a similar downward trend with the moisture content and springiness. The overall results showed that SRB stored at FT can retain the original quality and re-steaming before consumption was beneficial to edible quality. This study indicates scientific guidance for the consumption of SRB, provides theoretical support for the study of prolonging the storage time of SRB. GC-IMS combined with X-ray CT can be used as a potential tool for the evaluation of storage quality of food like SRB.

Electrospun starch-based nanofiber mats for odor adsorption of oyster peptides: Recyclability and structural characterization

The off-odor of seafood, which negatively affected its flavor and quality, was removed mainly by non-recyclable liquid-phase deodorization methods at present. In this work, octenylsuccinylated starch (OSS)-pullulan (PUL) nanofiber mats were regenerated after physical adsorption and thermal desorption of off-odor compounds in oyster peptides. The mat structure was characterized and the adsorption process was investigated. The regenerated nanofiber mats maintained a favorable appearance and microscopic morphology even after 25 adsorption-desorption cycles, with a reduction in average fiber diameter and average pore area, an increase in hydrophobicity and alterations in surface groups. Their adsorption rate first decreased and then stabilized as the number of cycles increased and was as high as 81.76% after 25 cycles. Correlation analysis revealed that the adsorption efficiency of regenerated nanofiber mats was related to their microstructure, surface groups and hydrophobicity. These findings could provide a theoretical basis for odor removal by electrospun nanofiber mats and their recycling.

Analytical prediction of fatigue resistance of additively manufactured aluminium alloy based on Murakami method

This research is devoted to analyze the stress state and fatigue strength of two specimens made by a newly developed high-strength aluminium alloy produced by the wire arc additive manufacturing (WAAM) process. The relationship between fatigue strength and flaw size was calculated based on the root squared area – a parameter by conventional Murakami’s equation which is a widely used analytical approach for predicting fatigue resistance in metallic materials. The research involves the metallographic preparation process on two aluminum alloy labeled HS-Al-A and HS-Al-B followed by Vickers hardness measurement. Further, the image of the observed pores was processed and dimensioned using an open-sourced software ImageJ by considering pixels and actual distance as well as by defining image threshold value for measuring pore sizes. The analytical approach is conducted in order to describe the maximum stress intensity factor Kmax at the crack front and to assess the fatigue strength σFS. As final results, specimen A has an average pore area of ≈65 µm with Kmax of 333.75 MPa∙√m and σFS of 137 MPa, while specimen B has an average pore area of ≈42 µm with Kmax of 325.13 MPa∙√m and σFS of 153 MPa. Overall, this research allows the formulation of a method for estimating fatigue strength of large defects leading to a conclusion that flaws can influence the fatigue resistance of the material so that the bigger the flaw size is, the lower σFS and the higher the Kmax.

Effect of rare earth Ce on the microstructure and mechanical properties of cast Al–7Si alloys

Casting experiments were carried out on Al–7Si using different additions of rare earth Ce at a reaction temperature of 1200 K. Based on the ternary phase diagram of Al–Si–Ce, the effects of rare earth Ce on the α-Al grain refinement, the mechanism of the eutectic Si phase modification, as well as on the mechanical properties and fracture morphology of the alloy were investigated. The results show that the addition of rare earth Ce generates a Ce-containing phase inside the alloy, which becomes a heterogeneous core of eutectic Si and changes the nucleation conditions of eutectic Si. The mechanical properties of the alloy were optimal when the Ce addition was 0.2 wt.%, and the defect porosity and average pore area were minimized. Ce-containing phases were found at fracture cracks, and these Ce-containing phases were deviated and aggregated at grain boundaries, which induced defects to be generated, and microcracks were easily produced during plastic deformation, which ultimately led to the fracture of the alloy. According to the growth kinetic relationship, due to the difference of different atomic radii, the inter-atomic forces lead to different nucleation densities of grains. With the generation of Ce-containing phases at the interfaces, the eutectic Si changes its growth direction and grows towards a 70° angle to the original direction with a tighter atomic ordering sequence of the stacking, and more twinned Si is generated and gradually stacked up at the interfaces, which directly alters the morphology of the eutectic Si.

Investigation of the relationship between gel strength and microstructure of surimi gel induced by dense phase carbon dioxide based on quantitative analysis

The microstructure of a surimi product determines its quality. Dense phase carbon dioxide (DPCD) can induce surimi gel formation, and the gel strength of the product are significantly better than that of heat-induced gels. The study analysed the changes of the surimi from golden pompano gel strength during the process of DPCD-induced gelation, and the changes of microstructure based on quantitative analysis of scanning electron microscope (SEM) image using ImageJ 1.42 software. The correlations between gel strength and microstructure was investigated. The results showed that the DPCD treatment significantly increased the cross-linking degree (CLD) and gel strength of surimi, compared with the raw surimi. The CLD and gel strength of surimi increased with the increase of DPCD treatment pressure, temperature and time. Quantitative microscopic analysis revealed that the number of pores (n) in the surimi gels increased and then decreased. The apparent porosity (ƞa), average pore area (Aa), average pore perimeter (Pa), fractal dimension (Df) and pore equivalent diameter (d) increased with the increase of DPCD treatment pressure, temperature and time. Correlation analysis showed that the CLD, ƞa, Aa, Pa, Df, d and median pore perimeter (Pc-50) were strongly positively correlated with the gel strength. In contrast, lacunarity (L) is strongly negatively correlated with the gel strength. The linear correlation coefficients between the CLD, ƞa and Df and the gel strength are 0.97, 0.95 and 0.96, respectively. These results provide a technical basis for DPCD to process high-quality surimi products. These findings also offer a novel approach for the testing and evaluating of the quality of surimi products.

Synthesis of phosphoric acid-based mesoporous geopolymers from tourmaline tailings for effective adsorption of tetracycline hydrochloride in aqueous environment

As a porous material, geopolymers (GPs) have attracted more attention for wastewater purification. Herein, a low-cost and environmentally friendly phosphoric acid-based tourmaline tailings geopolymers (PTMT-GP) were fabricated, and used as adsorbents for removal of tetracycline hydrochloride (TCH) in solution. The morphological and structural evolution of TMT after phosphoric acid attack was confirmed by XRD, SEM and FT-IR. The optimal PTMT-GP0.7 had the largest average pore and specific surface area, which were 3.89 nm and 115.66 m2 g−1, respectively. The observed adsorption process of TCH on PTMT-GP0.7 could be perfectly explained by pseudo-second-order kinetic model, and the maximum theoretical adsorption capacity, obtained from the Langmuir model, was 82.56 mg g−1 at 318 K and pH = 3. Thermodynamics indicated that the adsorption process of TCH on PTMT-GP0.7 was not only endothermic, but also feasible and spontaneous. The removal of TCH in aqueous by PTMT-GP0.7 suggested the combined effect of physical and chemical adsorption, including pore filling, electrostatic, H-bonding and ion exchange interaction. After 5 reuse cycles, PTMT-GP0.7 maintained 86.56% of the first saturated adsorption capacity for TCH, and the adsorption capacity of PTMT-GP0.7 calcined at 400 °C for 2 h decreased by 4.56%. This work will provide a valuable reference for evaluating the adsorption performance of phosphate-based geopolymer materials synthesized from tailings, which are expected to be a low-cost, green and stability adsorbent to remove TCH from wastewater.

The Curvature, Collagen Network Structure, and Their Relationship to the Pressure-Induced Strain Response of the Human Lamina Cribrosa in Normal and Glaucoma Eyes.

The lamina cribrosa (LC) is a connective tissue in the optic nerve head (ONH). The objective of this study was to measure the curvature and collagen microstructure of the human LC, compare the effects of glaucoma and glaucoma optic nerve damage, and investigate the relationship between the structure and pressure-induced strain response of the LC in glaucoma eyes. Previously, the posterior scleral cups of 10 normal eyes and 16 diagnosed glaucoma eyes were subjected to inflation testing with second harmonic generation (SHG) imaging of the LC and digital volume correlation (DVC) to calculate the strain field. In this study, we applied a custom microstructural analysis algorithm to the maximum intensity projection of SHG images to measure features of the LC beam and pore network. We also estimated the LC curvatures from the anterior surface of the DVC-correlated LC volume. Results showed that the LC in glaucoma eyes had larger curvatures p≤0.03), a smaller average pore area (p = 0.001), greater beam tortuosity (p < 0.0001), and more isotropic beam structure (p = 0.01) than in normal eyes. The difference measured between glaucoma and normal eyes may indicate remodeling of the LC with glaucoma or baseline differences that contribute to the development of glaucomatous axonal damage.

Experimental Study on Microstructure and Hydraulic Performance of Bentonite Modified Loess

The impact of natural sodium bentonite on the microstructure, permeability and strength characteristics of bentonite-modified loess (BML) were evaluated by scanning electron microscope (SEM) test, triaxial flexible wall permeability test, uniaxial compression test and direct shear tests. The experimental results indicate that bentonite can be used for loess solidification attributed to its effective particle filling, water absorption and expansion characteristics. The quantitative parameters of SEM images such as the average pore area, width, length and surface porosity of BML declined first and then increased with bentonite content, and the lowest was observed at a bentonite content of 15%. The hydraulic conductivity of BML declined with increasing bentonite content and was lower than the maximum allowable limit of 1.0 × 10−9 m/s. The uniaxial compressive strength and shear strength parameters of BML increased initially and subsequently declined as bentonite content increased. A normalized prediction model was established for modified loess based on the correlation between mechanical characteristics and the microscopic pore parameters, which was verified to be rational in estimating the macro- and micro-scale properties of BML. Therefore, when the anti-seepage landfill layers are constructed in the Loess Plateau area, 15% of bentonite is recommended in modified loess, which has optimal impermeability and mechanical properties.

A Review on Porosity Formation in Aluminum-Based Alloys

The main objective of this review is to analyze the equations proposed for expressing the effect of various parameters on porosity formation in aluminum-based alloys. These parameters include alloying elements, solidification rate, grain refining, modification, hydrogen content, as well as the applied pressure on porosity formation in such alloys. They are used to establish as precisely as possible a statistical model to describe the resulting porosity characteristics such as the percentage porosity and pore characteristics, as controlled by the chemical composition of the alloy, modification, grain refining, and the casting conditions. The measured parameters of percentage porosity, maximum pore area, average pore area, maximum pore length, and average pore length, which were obtained from statistical analysis, are discussed, and they are supported using optical micrographs, electron microscopic images of fractured tensile bars, as well as radiography. In addition, an analysis of the statistical data is presented. It should be noted that all alloys described were well degassed and filtered prior to casting.

Biosynthesis and Properties of a P(3HB-co-3HV-co-4HV) Produced by Cupriavidus necator B-10646.

Synthesis of P(3HB-co-3HV-co-4HV) copolymers by the wild-type strain Cupriavidus necator B-10646 on fructose or sodium butyrate as the main C-substrate with the addition of γ-valerolactone as a precursor of 3HV and 4HV monomers was studied. Bacterial cells were cultivated in the modes that enabled production of a series of copolymers with molar fractions of 3HV (from 7.3 to 23.4 mol.%) and 4HV (from 1.9 to 4.7 mol.%) with bacterial biomass concentration (8.2 ± 0.2 g/L) and PHA content (80 ± 2%). Using HPLC, DTA, DSC, X-Ray, SEM, and AFM, the physicochemical properties of copolymers and films prepared from them have been investigated as dependent on proportions of monomers. Copolymers are characterized by a reduced degree of crystallinity (Cx 38–49%) molecular weight characteristics Mn (45–87 kDa), and Mw (201–248 kDa) compared with P(3HB). The properties of the films surface of various composition including the porosity and surface roughness were studied. Most of the samples showed a decrease in the average pore area and an increase in their number with a total increase in 3HV and 4HV monomers. The results allow scaling up the productive synthesis of P(3HB-co-3HV-co-4HV) copolymers using Cupriavidus necator B-10646.