Numerical Simulation of the Mechanical Stirring Process in a Tannin-Based Foaming Precursor Resin

Tannin foam is a new functional material.It can be widely applied to the automobile industry,construction industry,and packaging industry due to its wide range of raw materials,renewable,easily degraded,low cost and almost no pollution.Preparing tannin foam is a very complex process that includes high temperature,two phases,mechanical agitation,and phase change.To investigate the influence of the stirring velocity and paddle shape,simulation was calculated by making use of the volume of fluid(VOF)method and multiple reference frame(MRF)method in a three-dimensional flow field of tannin-based foaming precursor resin.The gas holdup and velocity magnitude were analysed with various conditions of mechanical velocities and paddle shape in the stirring flow field.The result shows the higher the velocity,the greater the disturbance and paddle shape between the eggbeater and the Rushton turbine,obviously the paddle shape of the eggbeater with a wider range of agitation,which can entrap more air into the tannin-based foaming precursor resin in a short time.Especially when the speed is 1500 rpm,the flow field of the Rushton turbine comes out of a ditch,which decreases the efficiency of mass transfer;there is less air to mix into the tannin-based foaming precursor resin,which causes unevenness.At the same time,the eggbeater shows the marvelous capability of hybrid as it has two vortexes and multiple cycles that make a difference from the Rushton turbine,which has only one vortex and two upper and lower loops;the structure makes the flow field more stable allowed evenness of flow field tannin-based foaming precursor resin.The results reveal that it is beneficial for tannin-based foaming precursor resin to use an eggbeater with a speed of 1500 rpm to reduce the consumption of resources while obtaining a uniform flow field.

Improvement in lipid production and biodiesel quality of Pavlova sp.by monochromatic illumination

Pavlova sp.is not only one of the most popular microalgae in aquaculture,but also a source of high-quality biodiesel feedstock.With white light as a control(W),Pavlova sp.was cultured in this study under varying light quality,including monochromatic red light(R),blue light(B),and combinations thereof with different proportions(illuminators of m Rn B,comprised of m red light units and n blue ones,m+n=7),to examine the effects of illuminating light quality on biocomponent production and biodiesel quality.The results show that combined monochromatic light,especially 2R5B,3R4B,4R3B,and 5R2B,could improve the growth of Pavlova sp.The dry weight of harvested algae powder in the 5R2B group reached 418.03 mg/L,and was 22.65%higher than that in the control group(W).Lipid production under combined monochromatic light of 4R3B reached 107.86 mg/L,and was 25.61%higher than in the control(W).In addition,illumination using 4R3B increased the proportion of C16∶0(palmitic acid)and C16:1(palmitoleic acid)fatty acids in Pavlova sp.by 15.55%and 21.94%,respectively,which translates into improved biodiesel quality.All cetane numbers(CN)for 4R3B–6R1B were over 51,while iodine values(IV)and degrees of unsaturation(DU)were reduced,leading to more stable biodiesel suitable for longterm storage.In addition,protein production under 6R1B was as high as 31.56 mg/L,1.8 times greater than under W.Light quality is proposed as an effective tool to regulate biocomponent production by microalgae.

Preparation of Film Based on Polyvinyl Alcohol Modified by Alkaline Starch and Lignin Fiber

This study presents an easily prepared film based on alkaline starch-polyvinyl alcohol hybrid and lignin fiber as an additive(SPL film).The SPL film was prepared under acidic conditions through a polycondensation reaction of PVA and a mixture incorporating alkaline starch and lignin fiber from agriculture or forest source.The examination using scanning electron microscopy(SEM)showed that the surface of SPL film was smooth and the lignin fiber had good compatibility within the film hybrid.Electrospray ionization mass spectroscopy(ESI-MS)and fourier transform infrared(FTIR)investigations indicated that alkaline starch and lignin fiber reacted with PVA under acidic conditions and that–CH_(2)–O–groups were involved in the cross-linking of the SPL system.In addition,the SPL film exhibited only 4%light transmittance,which effectively reduces the ultraviolet and visible light(UV-Vis)penetration,along with good performance when exposed to thermal degradation,in which the mass loss reached around 60%at 400℃.More-over,the SPL film acquired excellent tensile strength,which is much higher than that of PVA-lignin(PL)composite film.

脲基超支化聚合物木材胶黏剂的合成与性能

脲基通常由异氰酸酯与氨基反应产生,由于异氰酸酯对人体健康和环境具有较大的危害且成本较高,因此利用低成本的尿素替代异氰酸酯合成脲基聚合物胶黏剂的途径正越来越受到关注。文中利用廉价的丙烯酸甲酯和对苯二胺为原料,通过迈克尔加成反应和酰胺化反应合成了树枝状四元胺,再与尿素在无催化剂和无溶剂的条件下进行A_(2)+B_(4)熔融缩聚,得到一系列低成本无醛的超支化脲基聚合物胶黏剂。利用核磁共振、红外光谱、质谱、凝胶渗透色谱等方法验证了其结构;差示扫描量热分析和热重分析表征了其热行为和热稳定性。最后将该脲基聚合物作为胶黏剂黏接不同基材,结果表明,粘接木材的剪切强度大于1.34MPa,远远高于GB/T17657-2013对II类板的要求,且其具有良好的耐水性;用于黏接有机玻璃、钢化玻璃、聚四氟乙烯、橡胶、玛瑙等基材也表现出较强的黏接力。

Soy Protein Isolate Non-Isocyanates Polyurethanes(NIPU)Wood Adhesives

Soy-protein isolate(SPI)was used to prepare non-isocyanate polyurethane(NIPU)thermosetting adhesives for wood panels by reacting it with dimethyl carbonate(DMC)and hexamethylene diamine.Both linear as well as branched oligomers were obtained and identified,indicating how such oligomer structures could further cross-link to form a hardened network.Unusual structures were observed,namely carbamic acid-derived urethane linkages coupled with lactam structures.The curing of the adhesive was followed by thermomechanical analysis(TMA).It appeared to follow a two stages process:First,at a lower temperature(maximum 130℃),the growth of linear oligomers occurred,finally forming a physically entangled network.This appeared to collapse and disentangle,causing a decrease of MOE,as the temperature increases.This appears to be due to the ever more marked Brownian movements of the linear oligomer chains with the increase of the temperature.Second,chemical cross-linking of the chains appeared to ensue,forming a hardened network.This was shown by the thermomechanical analysis(TMA)showing two distinct MOE maxima peaks,one around 130℃ and the other around 220℃,with a very marked MOE decrease between the two.Plywood panels were prepared and bonded with the SPI-NIPU wood adhesive and the results obtained are presented.The adhesive appeared to pass comfortably the requirements for dry strength of relevant standards,showing to be suitable for interior grade plywood panels.It did not pass the requirements for wet tests.However,addition of 15%of glycerol diglycidyl ether improved the wet tests results but still not enough to satisfy the standards requirements.

Effect of Post-Added Water Amount on Pre-Concentrated Bark Foaming Materials by Mechanical Stirring

In this study,pre-concentrated bark,furfuryl alcohol and other biomass raw materials were used to prepare foaming materials by high-speed mechanical stirring without using a foaming agent.We investigated the effect of the postadded water amount on the properties of foaming materials.In particular,we determined basic physical properties of these materials,including the limiting oxygen index(LOI),porosity,thermal conductivity,thermogravimetric analysis,pore size distribution,and microstructure.The results of scanning electron microscopy(SEM)indicated that the pore size distribution was uniform and the pore size increased with increasing water volume.Thermogravimetric analysis(TG/DTG)showed that when the temperature reached 410°C,the foam was easily decomposed,the final residual mass was only 2.8%,and water addition had little effect on it.Moreover,the amount of post-added water is 5–30 g,the density and compression strength of the foamed materials gradually decreased,while the degree of pulverization increased.LOI ranged from 26.1%to 30.79%,and porosity ranged from 81%to 83%.The change in water volume greatly affected the foam’s performance,the performance of foamed material deteriorated as the amount of added water increased,but the effect on thermal conductivity was not very obvious.The highest thermal conductivity was only 0.0179 W/(m·K),still providing excellent thermal insulation.

Development of Antioxidant Packaging Film Based on Chinese Bayberry Tannin Extract and Polyvinyl Alcohol

The current work explores the potential use of commercial Chinese bayberry tannin(BT)to develop antioxidant PVA-based films using solvent casting process for packaging applications.The effect of BT concentration on opa-city,water resistance and antioxidant capacity of resulting films was investigated.Properties like tensile strength,thermal behavior,and morphological aspects were also characterized.The experimental results showed that PVA/BT films formed with uniformly brown color and generally good transparency,offering good antioxidant ability.The PVA film containing BT presented slightly higher water resistance according to the results of moisture content and water vapor permeability,especially at low BT content(<10 wt%).The PVA can be compounded with up to 10 wt%BT without any obvious deterioration in the tensile strength.The PVA/BT films exhibited better thermal degradation behavior compared with PVA alone because of the chemical bonds of PVA-BT and the for-mation of char at high temperature.Based on the results,PVA incorporated with Chinese bayberry tannin may provide broader formulation options for packaging materials with antioxidant action.

Formaldehyde Free Renewable Thermosetting Foam Based on Biomass Tannin with a Lignin Additive

This study presents easily prepared free formaldehyde bio-based foam based on a prepared thermosetting resin comprising tannin–lignin–furfuryl alcohol-glyoxal(TLFG)via mechanical stirring in presence of ether as a foaming agent.The foam was developed through a co-polycondensation reaction of glyoxal and furfuryl alcohol with condensed tannin and lignin,which is a forest-derived product.Investigation using scanning electron microscopy(SEM)showed more closed-cell structure without cracks and collapse in the TLFG foam,with a higher apparent density with respect to tannin–furanic–formaldehyde(TFF)foam.Differential scanning calorimetry(DSC),dynamic thermomechanical analysis(DTMA),and thermogravimetric analysis(TGA)investigations revealed that the curing process of TLFG foam proceeds easily even at a lower temperature.Additionally,it acquired higher heat resistance than TFF foam.Moreover,TLFG has a more robust chemical network structure,which contributes efficiently to the mechanical strength and a lower pulverization degree compared with TFF-derived foam.Fourier transform infrared spectrometry(FTIR)and electrospray ionization mass spectrometry(ESI-MS)proved that the cross-inking reactions between tannin,lignin,furfuryl alcohol,and glyoxal have been proceeded efficiently.

Assisted Compatibility, and Balanced Regulation of the Mechanical, Thermal, and Antioxidant Activity of Polyvinyl Alcohol-Chinese Bayberry Tannin Extract Films Using Different Di-Aldehydes as Cross-Linkers

Polyvinyl alcohol(PVA)-based films containing Chinese bayberry tannin(BT)were prepared by cross-linking using glyoxal,glutaraldehyde and dialdehyde starch,individually.The presence of cross-linkers was evident to promote the transparency and decrease the moisture content of PVA/BT films,while the water solubility stayed almost unchanged in the cross-linked PVA/BTfilms.All cross-linkers provided promotion of the water vapor per-meability,mechanical property and thermal stability of PVA/BT films.The best water vapor barrier capacity was found in case of glutaraldehyde cross-linked PVA/BT film,while the highest tensile strength was encountered in case of glyoxal cross-linked PVA/BT films,compared with the uncross-linked films.The scavenging action of the films towards DPPH radical activity was influenced by the nature of each cross-linker.Namely,the PVA/AT film cross-linked by glutaraldehyde acquired the lowest radical scavenging activity in a certain time,suggesting that glutaraldehyde decreased the release rate of BT from PVA.Based on the experimental data,glutaraldehyde and dialdehyde starch could be more suitable for PVA/BT film preparation since they can promote the intermo-lecular interaction of PVA and BT to a reasonable extent.

Lightweight Biobased Polyurethane Nanocomposite Foams Reinforced with Pineapple Leaf Nanofibers (PLNFs)

Pineapple leaf nanofibers(PLNFs)extracted from pineapple leaf fiber were used for reinforcing biobased polyurethane foam(BPU).The dispersion performance of PLNF in the foaming mixture system,nanocomposite foaming behavior,cell morphology,cell size,density,compressive strength and dimensional stability were investigated.The viscosity of the mixtures increased with increasing the PLNF content.The addition of a tiny amount of PLNF did not influence the exothermic temperature of the foam system,but reduced the expansion and gel time of the nanocomposite foams.This reduced time was found to increase the production efficiency.Scanning electron microscopy(SEM)images showed that the PLNF neither affected the cell shape nor size.While the density of the foam was not obviously altered with the addition of a small amount of PLNF,the compressive strength and dimensional stability were significantly improved.

Tannin Resins for Wood Preservatives:A Review

Tannins and wood preservatives,in this article,are briefly introduced at beginning.The research and application progress on tannin resins for wood preservatives at home and abroad are reviewed.The significance and development prospects of research on tannins for wood preservatives are prospected.

Preparation and Characterization of Sandwich Structured Materials with Interesting Insulation and Fire Resistance

A cellular material in the form of 3-layered sandwich structure material was prepared via sole use of mechanical stirring without any use of a foaming agent,while Tween-80 was employed as a foam stabilizer via a developed in-situ mold casting.The resulting structure displayed a good appearance with no visual defects.The 3-layered composition of the sandwish structure,“nonporous resin layer-porous foam layer-nonporous resin layer”,was examined in terms of the microstructure,density&density distribution,pulverization ratio,mechanical strength,insulation and flame retardant performance.It was indicated from the results that the bonding between the resin layer and foam layer was tight,while the tensile rupture always occurred in the porous layer.Also,the density of the sandwich structure material was symmetrical with“saddle”distribution,and a uniform density for any given layer.The increase in the density at the interface layer provided a good interpretation for the tensile rupture never occurred at the interface.The brittleness resistance of the developed material was significantly improved,and the pulverization ratio was sharply decreased from 9.93%to 0.31%.The material acquired a thermal conductivity and limiting oxygen index(LOI)of 0.0241 W/m⋅K and 29.92%,respectively,indicating potential use of such materials broadly in fields of insulation and flame retardancy.

Preparation of an Abrasive Grinding Wheel Based on Tannin Resin Cross- Linked by Furfuryl Alcohol, Urea and Glyoxal

Simple bio-based abrasive grinding wheel based on thermosetting resin matrix was developed starting with condensed tannin and furfuryl alcohol,which are mainly derived from forest and agricultural products like tree barks,wheat and crops.Fourier transform infrared spectra(FTIR)signified the acidic conditions are quiet efficient for the reaction of furfuryl alcohol,urea and glyoxal all together and the-CH_(2)-NH-and-CH_(2)-O-CH(OH)-groups are predominating in cross-linking of the tannin-furfuryl alcohol-urea-glyoxal(TFUG)resin.The strengthening contribution of the tannin was also confirmed by the preservation of its distinct crystallinity using X-ray diffraction(XRD).Differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA)ensured that TFUG resin can be cured at low temperature and offer higher heat resistance compared with phenol-formaldehyde(PF)resin.The high hardness and excellent compressive strength revealed by the corresponding investigations such as Brinell hardness,compression resistance,and grinding tests suggested a strong abrasive ability using the new grinding wheel compared with lab-made grinding wheel based on PF resin.This could be ascribed to the absence of cracks and low content of formed holes as confirmed using scanning electron microscopy(SEM)and balanced reaction conditions that leads to network structure with regular local reinforcements and homogeneous crosslink density.

Differential Transform Method for Some Delay Differential Equations

This paper concentrates on the differential transform method (DTM) to solve some delay differential equations (DDEs). Based on the method of steps for DDEs and using the computer algebra system Mathematica, we successfully apply DTM to find the analytic solution to some DDEs, including a neural delay differential equation. The results confirm the feasibility and efficiency of DTM.

Preparation of cobalt ferrite nanoparticles using fulvic acid as a capping agent and its effect on catalytic activity

Cobalt ferrite was prepared by co-precipitation from cobalt and iron soluble precursors in presence of fulvic acid at different pHvalues, namely, 6 and 8 and compared with the same preparation in absence of fulvic acid. The presence of fulvic acid is expected tobind metal ions through bridging before co-precipitation and mineralization. The extent of binding is determined according to thepH of the process. This influences the mineralization of the resulting cobalt ferrite and the crystallization/ordering of its lattice. Inaddition, the extent of residual ferric oxide is also a function of the efficiency of binding process. This route of modification for the coprecipitationprocess was found to be accompanied by enhanced surface area and total pore volume for most of the prepared samples.The involvement of these oxides as catalysts in the photo-catalytic degradation of phenol from wastewater was found to contributevery efficiently and the removal reached about 88% in some cases, which can be attributed to olation and oxolation process of theformed nanoparticles.

Patterns of presence-absence variants in Upland cotton

Dear Editor,Sources of genetic variations in genomes include small-scale sources(such as single-nucleotide polymorphisms(SNPs),insertions/deletions(InDels),and simple sequence repeats and larger-scale structural variations(mainly presence-absence variants(PAVs))and copy number variants).PAVs are sequences that are either inserted or missing in genomes in comparison with a reference sequence or genome.PAVs can have a much longer sequence than SNPs and InDels,as illustrated in the human genome(Conrad et al.,2010).PAVs are important genomic structural variations that can directly affect genomic structure and key functional genes in the genome(Kumar et al.,2007).Moreover,the use of PAVs for studying quantitative traits has been valuable(Lam et al.,2010).