The effect of alginate on the mechanical,thermal, and rheological properties of nano calcium carbonate‐filled polylactic acid composites

Traditional plasticizers to modify polylactic acid (PLA) usually leads to limited biodegradation, due to its inherent non‐biodegradability of additives. In this work, we report a melt blending method to modify PLA using the alginic acid and two different alginates combined with nano CaCO₃, a fully sustainable and biodegradable component. And, the mechanical, thermal, and rheological properties of the composites are investigated. We demonstrated that the filled samples show a lower tensile strength and higher impact strength which means a toughening effect occurs. Dynamic mechanical analysis experiments showed that the calcium alginate‐filled samples show higher performances than other filled samples not only in static mechanical but also dynamic mechanical properties. The fracture morphology of the samples shows that a better interfacial reaction has been constituted for gel calcium alginate between CaCO₃ and PLA. Nevertheless, the thermogravimetric analysis results indicate that a lower thermal stability has been achieved in alginate filled samples. Chemorheological study indicated the alginate‐filled samples also show a lower modulus and viscosity than neat PLA. It was found that the complex viscosity decrease with the addition of alginates, in comparison with PLA/CaCO₃ composites, and the samples filled with calcium alginate show a higher viscosity than those of sodium alginate and alginic acid. The alginate derivatives showed interesting potential as new green plastic additives attributed to origin from the biodegradable natural resources with a polymeric matrix. POLYM. ENG. SCI., 59:1882–1888, 2019. © 2019 Society of Plastics Engineers     

聚乙烯醇/氧化石墨烯分离膜的结构与性能

成膜材料聚乙烯醇（PVA）易溶胀,稳定性差,氧化石墨烯（GO）具有很好的化学稳定性,以PVA为主要原料,GO为添加剂,聚乙二醇为造孔剂,采用共混法制备了GO含量不同的PVA/GO分离膜,并用光学接触角测量仪、超滤杯等考察了分离膜的亲水性和耐污染性;采用SEM、IR、TGA等表征了分离膜的微观形貌、热学及力学性能。结果表明：GO的加入改善了分离膜的内部孔道、亲水性、纯水通量和耐污染能力,膜的热稳定性和力学性能均得到提高,当GO含量为2%时,分离膜的综合性能达到最优。     

The effect of acid-base interaction on the thermal and transport properties of poly(etheretherketone) based composite membranes

Binary composite membranes were prepared by the solution casting method from sulfonated poly(etheretherketone) (SPEEK) and organic additives such as hydroxyquinolinesulfonicacid (HQS), 4-tertiary butylpyridine (TBP), imidazole and succinimide. Ternary composite membranes were prepared from SPEEK, inorganic phosphotungstic acid (PWA) and the same organic additives. The acid base interaction characteristics of the composite membranes were not observed by ATR-FTIR analysis. TGA results showed that the thermal stability of the composite membranes was enhanced in the temperature range up to about 400 °C by the addition of the organic additives. The acid-base interaction between SPEEK and the organic additives of HQS, TBP and imidazole decreased the water uptake, methanol permeability and proton conductivity of the binary and ternary composite membranes. However, the addition of succinimide did not decrease the water uptake, proton conductivity and methanol permeability of the composite membranes. The composite membranes containing succinimide made little acid-base interaction but made hydrogen bonding with SPEEK. The hydrogen bonding proved to be weaker than the acid-base interaction. The selectivity of the composite membranes increased by the addition of PWA, and the selectivities of the composite membranes containing succinimide were higher than those of the other composite membranes.     

Bacterial biosynthesis of alginates

Alginates are polysaccharides with many industrial and medical uses, from food additives to encapsulation agents in the emerging transplantation technologies. Alginate is composed of variable proportions of β‐D‐mannuronic acid and α‐L‐guluronic acid linked by 1–4 glycosidic bonds. Traditionally, commercial alginate has been produced by farmed brown seaweeds, but this alginate suffers from heterogeneity in composition and quality partly due to environmental variation. Two bacterial genera, Pseudomonas and Azotobacter, are also capable of producing alginate as an exopolysaccharide. These bacterial alginate producers can provide the means to produce alginates with defined monomer composition and possibly through genetic and protein engineering may allow for the production of ‘tailor made’ bacterial alginates. The paper discusses the mechanisms behind alginate production in bacteria and how they may be used in the commercial production of alginates. Copyright © 2010 Society of Chemical Industry     

低成本多孔非对称陶瓷过滤膜的制备与性能研究进展

陶瓷膜因具有机械强度高、耐高温、化学稳定性好、孔径分布可控、再生性能好和环境友好等诸多优势而被应用于众多行业。然而,其生产成本较高导致市场占有率低。此外,陶瓷膜还面临高渗透性和高选择性不能兼备的难题,这限制了其大规模应用。本文综述了采用廉价原料、添加烧结助剂和优化制备工艺来降低非对称陶瓷膜生产成本以及提高其性能方面的研究,分析了相关措施对陶瓷膜的利弊,并展望了陶瓷膜未来的发展方向和应用前景。     

添加剂对熔纺氨纶结构与性能的影响

基于添加剂与聚氨酯之间的化学与物理作用,选择了合适的聚合物和无机纳米颗粒等添加剂,研究了这些添加剂对熔纺氨纶制备及其对氨纶丝的微观结构和力学等物理性能的影响。研究结果表明:增塑剂S改善了氨纶的结晶特性,进而改善力学性能与热稳定性;添加剂的并用在一定程度上可改善氨纶丝弹性与耐疲劳性。     

Effect of different forms of nano-ZnO on the properties of PVDF/ZnO hybrid membranes

In this article, polyvinylidene fluoride (PVDF)/ZnO hybrid membranes with different forms of nano-ZnO as additives were prepared by thermally induced phase separation. The effects of the morphology of ZnO particles on the microstructure and properties of hybrid membranes were systematically investigated. Three different forms of nano-ZnO were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Then a series of tests were made through XRD, Fourier transform infrared, differential scanning calorimeter, SEM, energy-dispersive X-ray spectroscopy, atomic force microscopy, mechanical strength testing, porosity measurement, water contact angle measurement, pure water flux measurement, rejection measurement, flux recovery rate (FRR) measurement, and photocatalytic degradation testing to characterize the hybrid membrane. The results show that the hybrid membranes which were doped with different forms of ZnO have different structures and properties. Porous ZnO has the best modification effect on PVDF membranes. The PVDF/porous ZnO hybrid membranes' water flux and OVA rejection can reach 1.6 and 1.3 times of pure PVDF membrane, respectively, and its FRR can reach about 95%. The hybrid membrane doped with porous ZnO has excellent self-cleaning performance, and its degradation rate of MB can reach about 51%.     

Effect of additives on the properties and performance of cellulose acetate derivative membranes in the separation of isopropanol/water mixtures

In this work, various cellulose acetate (CA) membranes for pervaporation were prepared by the incorporation of different additives, i.e. polyethylene glycol-600 (PEG-600), propylene glycol (PG), and ethylene glycol (EG) to enhance the separation of isopropanol (IPA)/water mixtures. These membranes were characterized by FTIR, DSC, TGA, SEM and UTM. Each additive was responsible for its characteristic effect on the membrane morphology, mechanical strength, permeation flux and separation factor. The SEM micrograph showed that the additives were evenly dispersed in the membrane matrix with the formation of dense membranes. The UTM tests for the membrane reveled that both the Young's Modulus and tensile strength increased with the increase in additive contents. TGA studies for the CA/PEG blend membrane exhibited the highest thermal stability as compared to the CA/PG and CA/EG blends. For each of these synthesized membranes, the separation factor decreased while the permeation flux increased with the increase in additive contents, while the CA/PG membrane with 20 wt.% additive content showed highest permeation flux of 452.27 g/m²h.     

Thermomechanical properties of bitumen modified with crumb tire rubber and polymeric additives

In this paper, the influence of some additives on the rheological and technological properties of crumb rubber modified binders has been studied. The research has been mainly focused on the degree of bitumen modification, measured as the improvement of the mechanical properties, produced by the additives used, and the storage stability of these binders at high temperature. The experimental results obtained reveal that all the polymeric additives used yield an improvement in both rheological and technological properties of the binder. The storage instability of these binders has been associated to sedimentation processes of insoluble CR particles that strongly influence the mechanical properties of the binder. The additives and processing conditions selected in this study do not completely prevent problems associated with the poor stability of CRMBs during storage at high temperature. Nevertheless, the use of polyoctenamer, FT-wax or SBS-containing additives improves CRMB stability. In this sense, similar loss tangent values were found before and after hot storage of these binders.     

Chitosan–Graphene Oxide Composite Membranes for Solid-Phase Extraction of Pesticides

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan–graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.     

氧化石墨烯/磺化聚苯并咪唑高温质子交换膜的制备和表征

通过共混法和原位聚合法成功制备氧化石墨烯（GO）/磺化聚苯并咪唑（SPBI）质子交换复合膜。用FTIR及TEM表征了复合膜的结构,并测试了复合膜的热稳定性、力学性能、尺寸稳定性、含水率、酸掺杂率、氧化稳定性及质子电导率,重点考察不同制备方法、GO的加入对GO/SPBI质子交换复合膜结构和性能的影响。实验结果表明,GO在Y-GO/SPBI-1%复合膜中呈薄片状并良好分散。添加GO后复合膜的力学性能大幅提高,拉伸强度相较于Nafion 117膜（26.65MPa）提高了2.5倍。Y-GO/SPBI-1%复合膜热稳定性稍高于G-GO/SPBI-1%复合膜。Y-GO/SPBI-1%复合膜拥有与SPBI膜相当的含水率,比G-GO/SPBI-1%复合膜的含水率提高了51.36%,表明原位聚合法制备的膜具有良好的保水能力。原位聚合法制备的复合膜具有更高的酸掺杂率和更低的酸溶胀度,提高了膜的尺寸稳定性。Y-GO/SPBI-1%质子交换复合膜在相对湿度40%、160℃下具有最高的质子电导率0.113S/cm。GO上的含氧官能团有助于复合膜中质子的跳跃,原位聚合法使GO更均匀地分散在SPBI基质中,对复合膜质子电导率的提高起到关键作用。     

Controllable layer-by-layer assembly based on brucite and alginates with the assistance of spray drying and flame retardancy influenced by gradients of alginates

With the aim of tailoring and controlling surface assembly, multifunctional flame retardants (FRs) were obtained based on depositing alginates and silane coupling agents on brucite via the spray-drying-assisted layer-by-layer assembly technique. The assembly was controllable in both structure and gradient mass. Two series of FRs were named CuFR1-3 and NiFR1-3 based on the assembly content of metal alginates. With the assistance of spray drying, good compatibility between FRs and ethylene-vinyl acetate (EVA) was obtained, resulting in better mechanical properties. Meanwhile, the FRs improved flame retardancy and smoke suppression when used in EVA composites. With 55 wt % loading, composites with CuFR3 and NiFR1 passed UL 94 V-0 rating, while those with brucite were not rated. The peak of heat release rate decreased by 51.7 and 49.3% while the residue increased by 9.8 and 11.9%, respectively. The FRs also reduced the smoke and CO production rates. For the two series of FRs, the relationship between FR efficiency and alginate contents is different. The CuFRs assembled more copper alginates and exerted better flame retardancy caused by lower catalytic graphitization. NiFRs exerted a higher catalyzing efficiency at low assembly content. However, at high assembly content, the catalytic graphitization effect would decrease by thermally oxidized degradation leading to excess nickel alginates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47570.     

热稳定性添加剂对喷气燃料电导率的影响

针对热稳定性添加剂对喷气燃料电导率的明显改变作用,介绍了几种热稳定性添加剂、抗静电添加剂和其他添加剂在喷气燃料中的抗静电效果,重点考察了不同添加剂复配后对喷气燃料电导率的影响作用。讨论了热稳定性添加剂与抗静电添加剂和其他添加剂间相互作用对碳氢液体电导率的影响机理。     

Fabrications and applications of low cost ceramic membrane from kaolin: A comprehensive review

The application of low cost ceramic membrane from kaolin has attracted much interest due to its excellent mechanical stability, chemical and thermal resistivity and most importantly, because it is cost effective, in some cases, compared to polymeric membranes. The advantage of kaolin based ceramic membrane is its thermal properties that allow sintering at much lower temperature than alumina. Although many studies have been made on the application of kaolin based ceramic membranes, detailed discussions were scarcely made and the information on the fabrication of ceramic membrane from kaolin is very limited. This article is aimed to make a comprehensive review on ceramic membrane from kaolin for its fabrication methods and applications. An attempt is also made to show the future direction of the R and D on the kaolin based ceramic membrane.     

纳米TiO2复配添加剂对PVDF中空纤维膜结构和性能的影响

该文将纳米二氧化钛（TiO2）粒子与高分子致孔剂、非溶剂、表面活性剂和无机盐4类制膜添加剂复配处理,采用浸没沉淀相转化法制备聚偏氟乙烯（PVDF）-TiO2复合中空纤维膜。通过扫描电子显微镜、X射线衍射、能谱、拉伸试验、接触角测定和截留试验分别对复合膜的微观孔结构、晶相结构、Ti元素分布、机械性能、亲水性、过滤性能和抗污染性能进行了表征,讨论了纳米TiO2粒子对PVDF膜结构和性能的影响。结果表明通过改变复配添加剂中TiO2粒子的含量,可以有效调控复合膜的结构和性能。当复配添加剂中w（TiO2）为2％（占PVDF固含量的质量分数埘％）时,纯水通量由216L／m^2·h提高至402L／m^2·h,牛血清蛋白截留率由95％降低至90％,复合膜整体性能较为优异。     

Synthetic membranes containing schardinger cyclodextrin additives

The permeation characteristics of the isomers of such aromatics as dichlorobenzenes, nitrochlorobenzenes, xylenes, etc., through a Methocel HG membrane containing various amounts of Schardinger α-cyclodextrin and β-cyclodextrin additives were measured in liquid/liquid dialysis and pervaporation experiments. The results showed that the cyclodextrins are able to selectively mediate molecular transport through the Methocel HG membranes. In general, increased membrane selectivity and a decrease in permeation rates were observed. Permeation rates for some aromatic compounds were decreased several hundred times with only 25% amounts of additive cyclodextrins in the Methocel HG membranes. Concentration electrical potential and bi-ionic electrical potential in membranes containing the Schardinger cyclodextrin have been measured and also show that the cyclodextrins are able to induce ion transport selectively through nonionic membranes. Dynamic mechanical properties of Methocel HG membranes containing cyclodextrins suggest these additives to be antiplasticizing agents. A mechanism for the modification of the intrinsic membrane permeation properties by cyclodextrin additive involving antiplasticizing action by the additives plus induced tortuous diffusion, where the latter is a result of specific interactions between the cyclodextrin additive and the permeating molecules, is proposed.     

Chemical modification of polyethersulfone nanofiltration membranes: A review

Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self‐assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

高速挤出PVC通讯电缆绝缘材料

分析了国外高性能ＰＶＣ电缆料,在全部使用国产原材料和助剂的前提下,研制了高速挤出ＰＶＣ通讯电料。该料可以在很高的挤出速度下加下成薄壁电线在１０００ｍ／ｍｉｎ的速度下可长时间稳定加工,具有很好的电性能、机械性能及耐老化性能;加工时不存在口模冒烟现象,清模周期长;产品外观光滑,致密, 有光泽手感良好。     

Incorporating sepiolite and kaolinite to improve the performance of SPEEK composite membranes for proton exchange membrane fuel cells

SPEEK polymer based thermally crosslinked polymer membranes are prepared by sol-gel synthesis using kaolinite and sepiolite clays as additives. Characterization tests, ie, mechanical stability, thermal gravimetric analysis, ion exchange capability, swelling properties, water uptake capacities, electrochemical impedance spectroscopy analysis, and Fourier transform infrared spectroscopy (FTIR) analysis of the membranes were conducted. The sepiolite and kaolinite addition enhanced the thermal stability and the thermal crosslinking reduced the swelling capacity of the synthesized membranes. Proton conductivity results were increased from 0.172 to 0.268 S cm⁻¹ by adding 9% of kaolinite, and to 0.329 S cm⁻¹ at 80°C by adding 9% of sepiolite to the SPEEK membrane's polymer structure. The fuel cell current density and potential measurements of 141 mA cm⁻² and 84.6 mW cm⁻² were found respectively at 0.6 V for the SPEEK/S9 membrane, whereas values of 600 mA cm⁻² and 348 mW cm⁻² were found for the Nafion commercial membrane.     

Synthesis and characterization of low content of different SiO2 materials composite poly (vinylidene fluoride) ultrafiltration membranes

A comparison of the morphology and performance of virgin poly (vinylidene fluoride) (PVDF) ultrafiltration (UF) membrane, and PVDF-composite membranes with low content of two different SiO₂ (N-SiO₂ and M-SiO₂ particles) was carried out. Cross-sectional area and surface morphology of the membranes were observed by scanning electron microscopy and atomic force microscopy. Surface hydrophilicity of the porous membranes was determined through the measurement of a contact angle. Performance tests were conducted on the composite membranes through water flux and bovine serum albumin (BSA) retention. Average pore size and surface porosity were calculated based on the permeate flux. Thermal stability and mechanical stability were determined by thermogravimetric analysis and tensile stress tests. The results indicate that N-SiO₂/PVDF (P-N) membranes possessed larger average pore size and porosity, which led to higher water flux and a slight decline in BSA retention. On the other hand, M-SiO₂/PVDF (P-M) membranes had better mechanical stability and anti-fouling performance with enhanced membrane hydrophilicity and decreased membrane surface roughness. Both of the P-N and P-M membranes exhibited typical asymmetric morphology and improved thermal stability.