Insights into the thermochemical evolution of maleic anhydride-initiated esterified starch to construct hard carbon microspheres for lithium-ion batteries

Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.

The UV Aging Properties of Maleic Anhydride Esterified Starch/Polylactic Acid Composites

Esterified starch/polylactic acid（ES/PLA） blending composite was prepared by melting extrusion with maleic anhydride esterified starch and PLA as the raw materials. The composite was accelerated aging by using UV aging box, and its properties were characterized by Fourier transform infrared spectroscopy（FT-IR）, scanning electron microscopy（SEM）, X-ray diffraction（XRD）, thermo gravimetric analysis（TGA） and mechanical testing machine. FT-IR and SEM results show that the infrared absorption peak intensities of C-O, C-H, and C=O in aged samples decrease gradually with increasing aging time. The damage degree of surface and internal of aged samples increases gradually. XRD analysis results show that after aging treatment, the crystalline diffraction peak of thermoplastic esterified starch at 2θ = 21° disappears and the diffraction peaks of PLA at 2θ = 16.5° appear, indicating that the hydrolysis rate of esterified starch is greater than that of PLA. The crystallinity of PLA in aged sample shows an increasing trend at first followed by a decreasing one along with the increasing time of aging treatment, suggesting that the hydrolysis of amorphous regions of PLA is more preferential than its crystalline regions. Because of the influence of crystal structure and the change of composition structure, the initial decomposition temperature of aging test specimen gradually increases with the extension of aging time. The maximum decomposition rate temperature and residual mass increases at first, and then decrease after the aging time extending to 1600 h. As the aging time increases, the damage degree of combination interface between esterification starch and PLA is exacerbated, resulting in the tensile strength and bending strength of aged specimen decreasing gradually.

Insights into the swelling process and drug release mechanisms from cross-linked pectin/high amylose starch matrices

Cross-linked pectin/high amylose mixtures were evaluated as a new excipient for matrix tablets formulations,since the mixing of polymers and cross-linking reaction represent rational tools to reach materials with modulated and specific properties that meet specific therapeutic needs.Objective:In this work the influence of polymer ratio and cross-linking process on the swelling and the mechanism driving the drug release from swellable matrix tablets prepared with this excipient was investigated.Methods:Cross-linked samples were characterized by their micromeritic properties(size and shape,density,angle of repose and flow rate)and liquid uptake ability.Matrix tablets were evaluated according their physical properties and the drug release rates and mechanisms were also investigated.Results:Cross-linked samples demonstrated size homogeneity and irregular shape,with liquid uptake ability insensible to pH.Cross-linking process of samples allowed the control of drug release rates and the drug release mechanism was influenced by both polymer ratio and cross-linking process.The drug release of samples with minor proportion of pectin was driven by an anomalous transport and the increase of the pectin proportion contributed to the erosion of the matrix.Conclusion:The cross-linked mixtures of high amylose and pectin showed a suitable excipient for slowing the drug release rates.

Study on Various Compositions of Polyvinyl Alcohol and Starch Blends by Cross-Linking with Glyoxal

The aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch blends. The blends have been cross-linked with glyoxal to enhance its properties. The hydroxyl groups of PVA and starch react with glyoxal via formation of acetal bonds;hence crosslinking could take place. The cross-linking of glyoxal is observed in various analytical methods such as DSC and FTIR. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile shear strength, pencil hardness and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the cross-linking is directly proportional to starch, since the starch hydroxyl groups are easily accessible for reacting. The cross-linked blend showed better cohesion between its chains, thereby increasing glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.

Cross-Linking of Sago Starch with Furan and Bismaleimide via the Diels-Alder Reaction

This research paper describes the synthesis of thermo-reversible cross-linking of sago starch by grafting a furan pendant group(methyl 2-furoate)onto the starch backbone,followed by a Diels-Alder(DA)reaction of the furan functional group with 1,1′-(methylenedi-4,1-phenylene)bismaleimide(BM).The proof of principles was provided by FTIR and 1H-NMR analyses.The relevant FTIR peaks are the carbonyl peak(υC=O sym)at 1721 cm^(−1);the two peaks appeared after DA cross-linking,i.e.,at 1510 cm^(−1)(corresponding toυCH=CH BM aromatic rings,stretching vibrations),and at 1173 cm^(−1)(assigned to cycloadduct(C-O-C,δDA ring))while the^(1)H-NMR result shows evidence for the presence of a furan ring in the starch matrices(in the range ofδ6.3-7.5 ppm).The crosslinked starch product is indeed thermally reversible,as is evident from the appearance of exothermal(DA,temperature range of 50℃-70℃)and endothermal(retro DA,temperature range of 125℃-150℃)transitions in the DSC thermograms.This paper not only proves the thermal reversibility but also demonstrates that the final product properties(chemical,morphology,and thermal stability)can be tuned by varying the annealing temperature,BM intake,and reaction time.

Cross-linkedα-amylase aggregates on Fe3O4 magnetic nanoparticles modified with polydopamine/polyethyleneimine for efficient hydrolysis of starch

In this workα-amylase was immobilized on magnetic Fe3O4 nanoparticles with polyethylenimine(PEI)/polydopamine(PDA)coating or 3-aminopropyl triethoxysilane(APTES)for the first time via adsorption–precipitation–cross-linking.Compared with the freeα-amylase,the resultant magnetic cross-linkedα-amylase aggregates(PEI/PDA-M-CLEAs and N-M-CLEAs)exhibited excellent thermal and storage stability as well as pH stability.After storage at 25°C for 60 days,freeα-amylase only retained 60%of its initial activity,while PEI/PDA-M-CLEAs and N-M-CLEAs retained 80%and 78%of their initial activities,respectively.Furthermore,N-M-CLEAs and PEI/PDA-M-CLEAs showed good reusability.After 6 repeated uses,PEI/PDA-M-CLEAs and N-M-CLEAs still maintained 65%and 62%of their initial activities,respectively.Especially,PEI/PDA-M-CLEAs and N-M-CLEAs exhibited higher starch hydrolysis efficiency than freeα-amylase.The maximum dextrose equivalent(DE)values of starch hydrolysis by PEI/PDA-M-CLEAs and N-M-CLEAs reached 29.24%and 28.79%within 90 min,respectively.However,the maximum DE values of starch hydrolysis by the freeα-amylase was only 27.89%even in 150 min.The magnetic cross-linkedα-amylase aggregates could be introduced as effective biocatalyst for industrial applications in production of maltose syrups.

Effect of Starch Dodecenylsuccinylation on the Adhesion and Film Properties of Dodecenylsuccinylated Starch for Polyester Warp Sizing

A series of dodecenylsuccinylated starches( DSSs) with different degree of substitution( DS) were prepared via the esterification of dodencenylsuccinic anhydride with hydrolyzed cornstarch in aqueous dispersion for investigating the influences of starch dodecenylsuccinylation upon the performances such as apparent viscosity and surface tension of starch paste, film behaviors,and adhesion to fibers for warp sizing. It was found that the dodecenylsuccinylation was able to reduce the surface tension of cooked starch paste and enhance the adhesion of starch to polyester fibers. It was also capable of depressing the brittleness of native starch and improving the mechanical behaviours such as breaking elongation and work-to-break of starch film. Initial increase in DS level of dodecenylsuccinylation enhanced these positive effects,while excessively increasing the level resulted in marked reduction in tensile strength of starch film and significant decrement in reaction efficiency. X-ray diffraction patterns of starch films showed the dodecenylsuccinates derivatized onto the backbones of starch depressed the degree of crystallinity of starch film. Based on the paste behaviors, adhesion, and film properties, the dodecenylsuccinylation level is recommended in a range of 0. 015-0. 025 for sizing polyester warps.

Starch-Based Adhesives for Wood/Wood Composite Bonding: Review

Increasing global energy crisis and scarcity of petroleum resources has shifted focus of chemical industries to look for alternative raw material resources. The main focus of raw materials in wood adhesives, such as petroleum and natural gas [1] [2], would be gradually replaced by renewable biopolymers. Starch is a relatively inexpensive and renewable product from abundant plants, easy processing and it has been extensively used as binders, sizing materials, glues and pastes [3], but its bonding capacity is not strong enough to glue wood [4]. Extensive research has been carried out on improving the cohesive properties, especially water resistance, of starch-based adhesives. In starch-based wood adhesive many new approaches have come forward for effective use it in wood/wood composite adhesive giving comparable performance as synthetic adhesives. This review of starch-based adhesives is made with the focus on starch modification methods for improving properties of starch-based adhesives.

改性淀粉与聚乳酸共混物的结构与性能

可生物降解的聚乳酸(PLA)可用于替代化石燃料基聚合物,可再生淀粉改性PLA有利于其推广应用。采用湿法工艺制备了3种马来酸酐(MAH)改性玉米淀粉(CSM),与PLA共混制备了PLA/CSM的共混物,对改性淀粉和PLA与不同淀粉的共混物进行了结构与性能研究。红外分析表明,MAH可通过酯化接枝至淀粉上,MAH水溶液滴入淀粉水分散液中的淀粉酯化程度高于MAH直接加入淀粉水分散液接枝而得的,冷冻干燥得到的MAH改性淀粉由粒度仪测得的粒径小于热干燥的改性淀粉。差示扫描量热分析(DSC)和X射线衍射(XRD)分析表明,PLA中混入淀粉后易于结晶,结晶度也提高了,冷冻干燥的改性淀粉与PLA共混膜的结晶度高于热干燥改性淀粉共混的PLA膜,玻璃化转变温度有所下降,但仍高于52℃;扫描电镜(SEM)可观察到改性淀粉与PLA共混有较好的界面相容性,热失重分析(TG)表明PLA与改性淀粉共混后热稳定性降低,但5%热失重温度仍高于220℃,600℃残炭率有3%以上。湿法工艺可用于淀粉接枝MAH,改性后淀粉可用于PLA的共混改性以降低成本。

不同直链含量酯化淀粉的合成与性能

以甲酸为酯化剂,分别按一定比例与3种具有不同支链含量的天然淀粉混合,制备得到3种酯化淀粉——木薯酯化淀粉(EM)、玉米酯化淀粉(EN)和蜡质酯化淀粉(EW),借助傅立叶红外光谱仪(FTIR)、广角X射线衍射仪(XRD)、扫描电子显微镜(SEM)、热重分析仪(TG)等仪器对天然淀粉与酯化淀粉的结构性能表征分析;并进一步研究了不同直链含量的热塑性酯化淀粉与PBS共混后力学性能的改变。实验分析表明,淀粉酯化后显现疏水特性,且随直链淀粉含量的增加,疏水性增强。淀粉晶体结构被酯化淀粉破坏,结晶度与直链淀粉含量成正比,热损失率与支链淀粉含量成正比,具体为EM(237℃)>EN(235℃)>EW(231℃)。分子间的氢键相互作用降低,提高了淀粉的热塑性,且支链淀粉含量高的酯化淀粉塑化效果好。

添加交联酯化淀粉面包的制作工艺研究

在面包制作过程中,适量添加交联酯化淀粉能降低原淀粉的不良特性,改善面包品质,并提高面包中的膳食纤维含量,有益于人体健康。基于此,本研究通过单因素试验和正交试验对交联酯化淀粉面包的工艺配方进行优化。结果表明,添加交联酯化淀粉面包的最佳工艺参数为酵母添加量1.5%,加水量57.5%,加糖量12.5%,发酵时间140.0 min。采用此工艺制作的交联酯化淀粉面包颜色自然,纹理结构好,柔软且富有弹性,口感绵软细腻,具有自然面包香味,同时富含膳食纤维。

基于不同分子结构的OSA淀粉构建Pickering乳液及其释放特性研究

淀粉作为Pickering乳液的常用载体材料,在生物活性物质输送中有较广泛的应用。针对淀粉链结构对其Pickering乳液的影响,本研究以普通玉米淀粉(Corn)和蜡质玉米淀粉(Waxy)为原料,先经辛烯基琥珀酸(OSA)改性后,再分别经酸降解(Acid Degradation,AD)或酸热复合降解(Acid-heat Composite Degradation,AH)获得4种具有不同分子结构的淀粉基材料,并制备相应的Pickering乳液。通过傅里叶红外光谱、X-射线衍射分析、排阻色谱法对材料结构进行表征,并对相应的Pickering乳液的粒径、ζ-电位及释放特性等进行研究。结果表明,酸降解得到的辛烯基琥珀酸玉米淀粉酯(OSA-AD-Corn)具有一定的有序结构,且短链分子数量约为90.7%±0.02%,链长分布更为均匀。受链结构影响,OSA-AD-Corn Pickering乳液具有较小的尺寸和较大的表面电位。在后续的模拟消化实验中,该乳液在模拟小肠部位释放的游离脂肪酸达42.86%±0.54%。在功能因子控释方面,OSA-AD-Corn Pickering乳液可稳定递送姜黄素,在模拟胃液和小肠液中的释放率分别为52.48%±0.42%和27.98%±0.22%,相较于其他淀粉基载体材料,能控制更多的功能因子递送在小肠部位。本研究结果为活性功能因子的生物高效利用提供合适的载体材料。

高取代度淀粉醋酸酯的制备研究

本文就高取代度淀粉醋酸酯的制备进行了研究 ,讨论了原料的选择处理及制备过程中各因素的影响 ,为确定最佳的合成条件提供了依据。结果表明 ,选用优质淀粉原料并进行一定的改性处理 ,以对甲苯磺酸作催化剂 ,合理选配酯化剂 ,预先糊化并控制在低温反应 。

机械活化木薯交联酯化淀粉的制备及其性能研究

以机械活化木薯淀粉为原料,三偏磷酸钠为交联剂,醋酸酐为酯化剂,采用一步连续法制备机械活化木薯交联酯化淀粉,考察反应温度、交联剂用量、交联pH、交联时间、酯化剂用量、酯化pH、酯化时间等因素对交联酯化淀粉糊冷黏度的影响,并与原木薯淀粉合成的交联酯化淀粉进行比较,研究了产物的理化特性和结构。结果表明,各因素对机械活化木薯淀粉的交联酯化反应均有影响。对于机械活化1.0 h的木薯淀粉,在反应温度40℃、三偏磷酸钠1.0%、交联pH 10.0、交联时间2.0 h、醋酸酐用量0.5 mL、酯化pH 9.0、酯化时间60 min的条件下,所制备的机械活化木薯交联酯化淀粉糊的冷黏度由机械活化淀粉的847 mPa.s提高到3 225 mPa.s,淀粉糊液黏度的稳定性、抗酸性、抗老化性显著提高。交联酯化复合变性有利于形成淀粉的V型结构。

MAH改性方法对淀粉/聚乳酸界面相容性的影响

以玉米淀粉和聚乳酸(PLA)为原料,马来酸酐(MAH)为改性剂,通过熔融挤出法制备淀粉/PLA复合材料。研究了MAH分别作为增容剂和淀粉酯化剂这两种改性方法对淀粉/PLA相容性的影响,并对复合材料的熔融加工性能、力学性能和耐水性能进行了测试。X射线衍射(XRD)、扫描电子显微镜(SEM)和热重分析(TGA)结果都证明,MAH与原淀粉先进行干法酯化改性再与PLA复配制得酯化淀粉/PLA复合材料,比MAH作为增容剂直接添加制得原淀粉/MAH/PLA复合材料具有更好的界面相容性。受界面相容性提高程度的影响,酯化淀粉/PLA复合材料的熔融加工性能、拉伸强度、弯曲强度、断裂伸长率和耐水性能都优于原淀粉/MAH/PLA复合材料。

马来酸单淀粉酯的制备及其性能研究

以马来酸酐为酯化剂,丙酮为反应溶剂制备了马来酸单淀粉酯,并研究了产品的理化特性。讨论了活化木薯淀粉与马来酸酐的摩尔比、反应温度、反应时间对酯化淀粉取代度的影响。结果表明:当活化木薯淀粉与马来酸酐的摩尔比为1∶3,温度为50℃的条件下反应7 h,可得到取代度为0.297的产品。马来酸单淀粉酯黏度、透明度、储存稳定性和热稳定性等物理性能均优于原淀粉。

木薯酯化淀粉的干法快速制备及性质研究

以木薯淀粉为原料,以冰醋酸和醋酸酐为酯化剂,在加热条件下,干法快速制备醋酸酯化淀粉。探讨了酯化过程中的影响因素及各因素对取代度的影响。研究了产品糊的透明度、膨胀度、黏度、溶解度以及冻融稳定性和抗相分离能力,并通过红外光谱对产品进行结构表征。结果表明:当木薯淀粉用量15.0 g,冰醋酸用量15.0 g,醋酸酐用量7.5 g,反应温度185℃,反应时间8 min时,产品的取代度可达0.076。与原木薯淀粉相比,醋酸酯化木薯淀粉透明度、黏度、膨胀率和溶解度增大冻融稳定性和抗相分离能力提高。红外光谱显示乙酰基团已引入淀粉分子链中。

月桂酸酯化淀粉/聚乙烯醇共混膜的制备及其性质研究

为了制备酯化淀粉/聚乙烯醇(PVA)共混膜,拓宽长链脂肪酸酯化淀粉的加工应用范围,以玉米淀粉制备的月桂酸酯化淀粉为原料,采用流延法制备淀粉/PVA共混膜,并对共混膜的显微结构、机械性能和热特性进行表征。结果表明,月桂酸酯化改性增加共混膜的表面的光滑性,提高共混膜的透明度和断裂伸长率,但对共混膜的耐水性和抗拉伸强度改善不明显;热重分析结果表明酯化淀粉共混膜与原淀粉共混膜相比,其热分解更不完全。月桂酸酯化改性能有效提高淀粉与PVA的相容性,扩大淀粉/PVA共混膜的应用范围。

硬脂酸木薯淀粉糊精的理化性质研究

本文以木薯淀粉为原料制备硬脂酸木薯淀粉糊精,研究了硬脂酸木薯淀粉糊精的理化性质。结果表明木薯淀粉经过酸解、酯化其理化性质发生了显著改变,与原淀粉相比,其溶解度、透明度、乳化性及冻融稳定性都提高,糊粘度降低。

精纺毛纱上浆配方的优化设计

文章旨在选择一种适合于精梳毛纱上浆的最佳配方,采用接枝淀粉、酯化淀粉、丙烯酸类浆料,设计了10个浆料配方,在浆纱小样机上以相同的工艺参数进行上浆,对各个配方浆纱后纱线的断裂强力、断裂伸长、耐磨性、毛羽指数等指标进行测试和比较。实验表明:与酯化淀粉相比,接枝淀粉更适于毛纱上浆,接枝淀粉与丙烯酸类浆料组合的最佳比例为80∶20。