Synthesis, isolation and characterization of methyl levulinate from cellulose catalyzed by extremely low concentration acid

A direct synthesis of methyl levulinate from cellulose alcoholysis in methanol medium under mild condition(180 210 C)catalyzed by extremely low concentration sulfuric acid(0.01 mol/L)and the product isolation were developed in this study.Effects of different process variables towards the catalytic performance were performed as a function of reaction time.The results indicated that sulfuric acid concentration,temperature and initial cellulose concentration had significant effects on the synthesis of methyl levulinate.An optimized yield of around 50%was achieved at 210 C for 120 min with sulfuric acid concentration of 0.01 mol/L and initial cellulose concentration below 100 g/L.The resulting product mixture was isolated by a distillation technique that combines an atmospheric distillation with a vacuum distillation where n-dodecane was added to help distill the heavy fraction.The light fraction including mainly methanol could be reused as the reaction medium without any substantial change in the yield of methyl levulinate.The chemical composition and structural of lower heavy fraction were characterized by GC/MS,FTIR,1H-NMR and13C-NMR techniques.Methyl levulinate was found to be a major ingredient of lower heavy fraction with the content over 96%.This pathway is efficient,environmentally benign and economical for the production of pure levulinate esters from cellulose.

Hydration Heat Effect of Cement Pastes Modified with Hydroxypropyl Methyl Cellulose Ether and Expanded Perlite

Hydration heat effect of cement pastes and mechanism of hydroxypropyl methyl cellulose ether （HPMC） and expanded perlite in cement pastes were studied by means of hydration exothermic rate, hydration heat amount, FTIR and TG-DTG. The results show that HPMC can significantly delay the hydration induction period and acceleration period of cement pastes. As mixing amount increased, hydration induction period of cement pastes enlarged and accelerated period gradually went back. At the same time, the amount of hydration heat gradually decreased. Expanded perlite had worse delay effects and less change of hydration heat amount of cement pastes than HPMC. HPMC changed the structure of C-S-H during cement hydration. The more amount of HPMC, the more obvious effect. However, EXP had little influence on the structure of C-S-H. At the same age, the content of Ca （OH）2 in cement pastes gradually decreased as the mixing amount increase of HPMC and expanded perlite, and had better delay effect than that single-doped with HPMC or expanded perlite when HPMC and expanded nerlite were both dooed in cement pastes.

Influences of Carboxyl Methyl Celluloseon Performances of Mortar

Carboxyl methyl cellulose （CMC） was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of mortar with CMC were studied. The water absorption was studied with the method of filter paper. The micro mechanism was researched with X-ray diffraction and scanning electron microscopy（SEM）. The experimental results show the water-holding performance of mortar with CMC is largely improved and it is better when the mixed amount is about 1.5%; the compression strength had a descending trend with the increase of CMC; CMC reacted with calcium hydroxide（CH） into the deposition of calcium carboxyl methyl cellulose.

Selective production of acetol or methyl lactate from cellulose over RuSn catalysts

Designing a catalytic system that could convert cellulose to switchable C3 alcohols or esters with controllable selectivity is highly desired to meet the rapidly changing market demand.Herein,we develop RuSn catalysts with the altering Sn loadings that can achieve acetol formation from cellulose hydrogenation at240℃in presence of H_(2)or yield methyl lactate production from cellulose conversion in methanol and water mixture at 200℃in presence of N_(2).The increased Sn contents from 3%to 6%lead to form different surface sites from Ru_(3)Sn_(7),Ru,and SnO_(x)to Ru_(3)Sn_(7)and SnO_(x).The integrated Ru_(3)Sn_(7),Ru,and SnO_(x)species on 1.5%Ru-3%Sn/SiO_(2)catalyze isomerization,retro-aldol condensation,and hydrogenation individual steps with coordinated reaction rates,resulting in the acetol formation with a high yield of 53.7 C%.Furthermore,the optimum combination of Ru_(3)Sn_(7)and SnO_(x)on 1.5%Ru-6%Sn/SiO_(2)contributes to the isomerization,retro-aldol condensation,dehydration,and 1,2-hydride shift,giving rise to the preferential production of methyl lactate at a 25.1 C%yield.These results illustrate the feasibility of controlling the selective conversion of cellulose to C3 acetol or methyl lactate by devising a tunable catalytic system,which guides the rational design of catalysts for the selective conversion of cellulose.

Regulating the Function of Nanocomposite Made from Hydroxypropyl Methyl Cellulose with Bacterial Cellulose Nanocrystal

Hydroxypropyl methyl cellulose(HPMC)-based hybrid nanocomposites reinforced with bacterial cellulose nanocrystals(BCNC) were prepared and characterized.The HPMC nanocomposites exhibited good thermal stability,with a thermogravimetric peak temperature of around 346℃.The addition of BCNC did not significantly affect the thermal degradation temperature or improve the transparency of HPMC nanocomposites.However,the addition of BCNC favorably affected the light scattering properties of the nanocomposites and enhanced mechanical properties such as tensile stress and Young's modulus from 65 MPa and 1.5 GPa up to 139 MPa and 3.2 GPa,respectively.The oxygen permeability of the HPMC nanocomposites also increased with increase in the amount of BCNC added.

Development of Preparation Method for Microencapsulating Uycalyptus Oil Containing Fine Aqueous Droplets by Use of Interfacial Condensation Reaction between Hydroxy Propyl Methyl Cellulose and Tannic Acid

It was tried to develop the preparation method for microencapsulating the uycalyptus oil containing fine aqueous droplets by using the interfacial condensation reaction between hydroxyl propyl methyl cellulose and tannic acid. Uycalyptus oil containing fine aqueous droplets was dispersed in the continuous water phase to form the (W/O)/W emulsion. Tannic acid and hydroxyl propyl methyl cellulose were dissolved in the inner aqueous droplets and in the outer continuous water phase, respectively. Tannic acid transferred through the oil phase from the inner water droplets to the interface between the oil phase and the continuous water phase and then, reacted with hydroxyl propyl methyl cellulose. In the experiment, the concentrations of hydroxyl propyl methyl cellulose and tannic acid were mainly changed stepwise. The uycalyptus oil containing the fine water droplets could be microencapsulated satisfactorily. It was found that the microcapsules were composed of the gelated hydroxyl propyl methyl cellulose film as the shell, the fine aqueous droplets as the first core and the oil droplet as the second core.

Emulsion Graft Polymerization of Methyl Methacrylate onto Cellulose Nanofibers

Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-phenanthroline N1,N10)zinc(II) complex (Phen-DEZ) with oxygen as the radical initiator. The effects of reaction temperature, initiator concentration, and monomer content on the grafting reaction were investigated. The molecular weight of the non-grafted PMMA, which was produced during graft polymerization, was more than 1 million, as determined by size exclusion chromatography. The PMMA-grafted CNFs were analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, which confirmed the grafting of PMMA on the nanofiber surface. The study presents a strategy for the grafting of high-molecular weight PMMA onto CNFs in an emulsion system using Phen-DEZ and O2.

Determination of Antimicrobial Activity of Methyl Cellulose Films Enriched with Some Essential Oils on Listeria innocua

Essential oils are effective antimicrobials on important some pathogenic bacteria and can be added packaging materials due to absorb various surfaces. In this study, the aim is to determinate of antimicrobial effects of methyl cellulose films with containing various proportions thyme, rosemary, coriander, basil and pimento berry oils （1%, 2%, 3% and 4% g/cc） against important bacteria as a surface contaminant Listeria innocua by in vitro. For this purpose, 1 cm diameter discs were cut from methyl cellulose films containing essential oils and inhibition zone diameter which were measured by the agar diffusion method. As the results of these analyses, all prepared active edible methyl cellulose films were antimicrobial effects on Listeria innocua. The most powerful antimicrobial effect achieved with methyl cellulose film including coriander oil on Listeria innocua. And also the weakest antimicrobial effect achieved with methyl cellulose film including rosemary oil on Listeria. All results were significant by statistically （p 〈 0.01） and all analyses were replicated in three times.

REFRACTOMETRY AND TEXTURES OF METHYL-CYANOETHYL CELLULOSE/DICHLOROACETIC ACID LIQUID CRYSTA LLI NE SOLUTIONS^+

An Abbe refractometer with a rotatable polarizer mounted on the eyepiece is used for determining the two principal refractive indices of methyl-cyanoethyl cellulose/dichloroacetic acid liquid crystalline solutions. The critical concentration where the mesophase appears can be determined according to the variation of the increment of the refractive index with the concentration. Mesophase textures of the liquid crystalline solutions are observed and the influence of the concentration on mesophase textures is also discussed.

丝素蛋白联合壳聚糖基热敏水凝胶的性能评估

目的在壳聚糖(CS)/羟丙基甲基纤维素(HPMC)热敏水凝胶的基础上,利用丝素蛋白(SF)与CS交联,构建CS/HPMC/SF水凝胶,研究SF对水凝胶的性能影响。方法共混法制备CS/HPMC混合溶液,向其中分别添加1%、5%、10%的SF溶液及交联剂京尼平,加入圆柱形模具中,升温至37℃,使溶液转为凝胶态。对水凝胶进行形貌、傅里叶变换红外光谱仪(FTIR)、X射线衍射(XRD)以及亲水性及力学性能表征检测。结果扫描电子显微镜下观察水凝胶为多孔状,随着SF的加入,孔隙减少,出现裂痕。FTIR和XRD结果显示,CS与HPMC混合后结晶程度改变,当加入SF后,SF与CS发生化学交联,结构发生转变,水凝胶的亲水性也因此减弱。力学表征显示,当SF的添加量为5%时,水凝胶的回弹性最优,弹性模量最大,且基本保持不变。结论SF与CS的交联改进了CS基热敏水凝胶的性能,相比于其他组水凝胶,CS/HPMC-5%SF保持良好的亲水性且具有较好的力学性能。

聚乙二醇对稻秸纤维/PHBV复合材料性能的影响

以稻秸原料制备的纳米纤维素(NCC)为增强相,聚羟基丁酸戊酸酯(PHBV)为基体材料,聚乙二醇为界面相容剂,采用溶剂浇筑法制备了稻秸NCC/PHBV复合材料。利用FTIR、XPS和DSC探讨了聚乙二醇的添加量(质量分数5%、10%、15%、20%、30%)对纳米复合材料界面结合性能和结晶性能的影响。结果表明,聚乙二醇可以与稻秸NCC、PHBV之间形成较强的氢键、C—O、O—C—O和CO,改善两者之间的界面相容性。聚乙二醇的加入可以降低纳米复合材料的结晶温度和结晶度,当聚乙二醇的添加量达到30%时,纳米复合材料的结晶温度降低了20.4℃,结晶度降低了53%。

聚乙醇酸与羟丙基甲基纤维素用于远端胰腺切除模型术后缝合的有效性和安全性评估

目的探讨应用聚乙醇酸(polyglycolic acid,PGA)与羟丙基甲基纤维素(hydroxypropyl methylcellulose,HPMC)复合材料在远端胰腺切除术后缝合中的有效性和安全性。方法选用36只健康成年比格犬,将其随机均分为观察组和对照组,每组各18只行远端胰腺切除手术。观察组实验犬使用PGA+HPMC复合材料进行切口加固;对照组实验犬使用NEOVEIL进行切口加固。术前、术后3 d及解剖前,分别对各组实验犬进行血常规检测。设置2周、4周、8周观察周期,每个观察点各6只动物进行心肝脾肺肾组织学检查、硬组织切片病理诊断等评估,并进行安全性评价。结果观察组和对照组实验犬在术前血常规检测比较差异无统计学意义。重复测量方差分析结果显示,不同时间点的白细胞计数(WBC)(F=14.875,P=0.001)、平均红细胞血红蛋白浓度(MCHC)(F=5.049,P=0.009)、中性粒细胞百分比(Neu%)(F=4.794,P=0.011)、红细胞计数(RBC)(F=6.591,P=0.002)、血红蛋白(HGB)(F=8.154,P=0.001)、红细胞比容(HCT)(F=5.281,P=0.007)、血小板计数(PLT)(F=6.560,P=0.014)、红细胞分布宽度变异系数(RDW-CV)(F=33.950,P=0.039)、淋巴细胞百分比(Lym%)(F=3.299,P=0.043)均值存在差异,但观察组和对照组组间无统计学差异,且时间与组别交互作用对其无显著影响,表明两组实验犬均出现了炎症反应或手术应激。两组实验犬在术后8周的硬组织病理切片评分中,观察组和对照组实验犬的炎症与坏死相关评分、纤维化、修复等相关评分和总分方面差异均无统计学意义(P>0.05)。两组实验犬在术后8周的解剖中,均未发现心肝脾肺肾等器官有明显的损伤,也未发现缝合材料残留、胰液渗漏或胰瘘等情况,表明两组缝合材料均已完全被吸收代谢,且切口愈合良好不会对内脏器官造成不良影响。结论PGA与HPMC是一种有效和安全的术后缝合材料,具有良好的生物可降解性、生物相容性、缝合强度和创面愈合质量,可以在远端胰腺切除术后缝合中与传统的可吸收性加固材料相媲美,为其在临床上的应用提供了科学依据。

磺化纤维素吸附剂的制备及其对咪唑离子液体的吸附性能研究

为了开发低成本、环境友好的离子液体吸附材料,在均相体系中,以微晶纤维素为基材,过硫酸铵为引发剂,甲基丙烯酸甲酯为单体,制备了纤维素接枝共聚物,再通过磺化作用制备了磺化纤维素(CMS)吸附剂。通过傅里叶变换红外光谱仪表征了CMS的结构,研究了反应温度、单体用量对接枝率的影响以及吸附时间、pH、吸附剂用量对1-丁基-3-甲基咪唑氯盐([Bmim]Cl)的吸附性能。结果表明:在吸附时间为45min、吸附剂用量为20mg、溶液pH=6.8条件下,CMS对[Bmim]Cl的吸附效果较好。

纤维素醚改性粉煤灰基薄喷材料性能研究

采用纤维素醚(羟乙基纤维素醚、羟丙基甲基纤维素醚)对粉煤灰基薄喷材料的粘结性能进行改性研究,研究了纤维素醚的黏度、取代基对粉煤灰基薄喷材料粘结强度、稠度及其抗拉强度、抗压强度的影响规律。采用扫描电子显微镜研究了纤维素醚掺入前后粉煤灰基薄喷材料28 d试样的微观结构,揭示了纤维素醚对薄喷材料粘结性能改性机理。结果表明,加入纤维素醚后,薄喷材料的粘结强度显著提高。相同取代基下,掺入低黏度的纤维素醚试样的粘结性能更高。不同取代基下,羟乙基纤维素醚试样粘结强度更高,对力学性能的不良影响更小。掺入0.05%(占胶凝材料质量分数)羟乙基纤维素醚的粉煤灰基薄喷材料28 d粘结强度达到1.67 MPa,抗压强度为11.4 MPa。

镁酞菁/PHBV催化薄膜的制备及光催化性能研究

将四氨基镁酞菁(MgPc)负载到PHBV上制备复合催化薄膜(MgPc/PHBV)。采用XRD、FT-IR、TGDTA和UV-Vis DRS等表征技术对MgPc/PHBV的结构和性质进行表征。结果表明,MgPc和PHBV之间可能通过物理作用结合;MgPc的加入降低PHBV的结晶度;并且将PHBV的分解温度提高20℃。基于UV-Vis DRS的测试表明MgPc/PHBV薄膜具有可见光催化活性。此外,MgPc/PHBV光催化降解有机污染物甲基橙的结果表明,光照、MgPc/PHBV和H_2O_2同时存在时才能催化氧化甲基橙;光照160 min后,甲基橙剩余率为0.0%,甲基橙完全被降解。光催化氧化反应中羟基自由基发挥着关键作用。

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.

膦酸功能化纤维素的制备及其对Au(Ⅲ)的吸附富集性能

为处理黄金冶炼工业产生的含金废水并实现其资源化利用,本研究通过多氨基多醚基甲叉膦酸与纤维素反应,设计合成了膦酸功能化纤维素(P-PC)吸附分离材料,利用红外光谱(FT-IR)、扫描电镜(SEM)对产物进行了表征分析。研究了P-PC对水溶液中Au(Ⅲ)的吸附富集性能。吸附实验表明,P-PC对Au(Ⅲ)的吸附行为符合伪一阶和伪二阶动力学模型及Langmuir等温吸附模型。当pH值为1.0时,P-PC对Au(Ⅲ)的吸附性能最佳。经过3次吸附与解吸循环后,P-PC对Au(Ⅲ)的吸附量仍超过0.5 mmol·g^(-1)。P-PC在吸附富集Au(Ⅲ)方面具有潜在的应用前景。

RAFT法制备羧甲基纤维素接枝丙烯酸酯共聚物

以溶解后改性的羧甲基纤维素(CMC)为大分子引发剂,S-1-十二烷基-S’-(α-α’-二甲基-α”-乙酸)三硫代碳酸酯为可逆加成断裂链转移聚合(RAFT)试剂,通过RAFT法制备了CMC接枝丙烯酸酯的新型接枝共聚物。为了进一步探索共聚物的成膜形态,设计了不同反应时间、不同甲基丙烯酸甲酯(MMA)与丙烯酸丁酯(BA)配比的反应条件,合成了CMC接枝MMA嵌段BA聚合物(Cell-g-PMMA-b-PBA)。结果表明:在反应时间为24 h,MMA与BA体积比为6∶1的条件下,Cell-g-PMMA-b-PBA的成膜性能最好,热稳定性高。

甲基纤维素对PP/EVA/GF浮纤现象及性能的影响

将甲基纤维素(MC)填充于聚丙烯/乙烯-醋酸乙烯酯共聚物/玻璃纤维(PP/EVA/GF)复合体系制备了PP/EVA/GF/MC。研究了MC对PP/EVA/GF的力学性能、微观结构、结晶性能和流动性能的影响。结果表明,在MC用量2份的情况下,PP/EVA/GF/MC表现出优异的力学性能,其拉伸强度为20.20 MPa,弯曲强度为38.79 MPa,分别比PP/EVA/GF提高了12.97%和56.28%。加入MC能有效改善PP/EVA/GF的浮纤现象,制品表面玻纤数目明显减少。PP/EVA/GF/MC结晶度为35.72%,比PP/EVA/GF结晶度提高了4.97%。剪切速率低于100 s^(-1)时,PP/EVA/GF/MC黏度低于PP/EVA/GF,表明MC能提升PP/EVA/GF的流动性。

海藻酸钠载药口腔速溶膜的制备及性能研究

针对当前药物突释、利用率低和持续释放等问题,以海藻酸钠(SA)和羟丙甲基纤维素(HPMC)为成膜剂,采用流延成膜的方法制备了海藻酸钠口腔速溶膜,对其化学结构、透光性和水溶性进行了分析,得到最佳的SA和HPMC的成膜比例,在此基础上,负载盐酸苄达明(BH)制备海藻酸钠载药口腔速溶膜。结果表明,最佳成膜比例为w(SA):w(HPMC)=1:2;另外,当BH负载量为30%时,海藻酸钠载药口腔速溶膜力学性能最好,当负载量为40%时,其包封率和载药效率最佳,经济成本更好。