淀粉颗粒聚集态结构研究进展

详述了淀粉颗粒中直链淀粉和支链淀粉的分子结构和分布位置,结晶结构及聚集态结构,以及颗粒的晶体结构与形状之间的关系等最新研究成果,同时对淀粉颗粒聚集态结构的研究方向提出展望。认为直链淀粉是分散在支链淀粉分子中且更集中于颗粒表面;颗粒表面比颗粒内部的支链淀粉分子具有更多的短支链。A型多晶淀粉比B型多晶淀粉具有更为松散的内部结构,因而后者对酸和酶具有更强的抗性。     

微波辐射对高链玉米淀粉热性质的影响

采用微波对30%水分含量的高链玉米淀粉进行处理。结果表明,微波处理降低了淀粉的膨胀度和溶解度、冻溶稳定性以及焓值,提高了糊化转变温度及转变温度范围。高链玉米淀粉经处理后糊化起始温度升高、黏度降低,黏度曲线由C型变为D型。以上表明在淀粉颗粒内无定型区和结晶区的直链淀粉与直链淀粉、直链淀粉与支链淀粉发生交互作用,产生了新的不同稳定性的结晶体,从而导致微波淀粉内部更加有序的结晶排列。     

离子液体中无催化剂法合成淀粉醋酸酯的结构与性能

以离子液体(ILs)氯化1-丁基-3-甲基咪唑(BMIMCL)为反应介质,无催化剂均相合成了高取代度的高直链玉米淀粉醋酸酯,利用红外光谱(FT-IR)、核磁共振(1H-NMR)、X射线衍射(XRD)和热重分析(TGA)对不同取代度(DS)的淀粉醋酸酯进行表征。结果表明,在BMIMCL中,无催化剂条件下,高直链玉米淀粉可与醋酸酐发生较好的均相反应,所合成的淀粉醋酸酯不存在淀粉原有的颗粒结构和结晶结构。并且,随着取代度的增加,XRD曲线中9°处的弥散峰增强,其热稳定性逐步提高。     

高直链玉米淀粉颗粒的形貌与结构

采用偏光显微镜、扫描电子显微镜、激光粒度分布分析仪和X射线衍射仪研究高直链玉米淀粉的颗粒形貌与结构。结果表明,高直链玉米淀粉具有十字偏光现象;颗粒形态圆滑、形状多样,大多为近似椭圆形、少数呈细长条等特殊形和无规则形,大多数颗粒表面有多个乳状突起,少数颗粒表面有孔洞或裂口,极少数颗粒表面的局部有裂纹,颗粒为实心;颗粒粒径为3.5μm~30.0μm,平均粒径为10.2μm;颗粒晶型结构为B型,结晶度为21%。高直链玉米淀粉的颗粒形貌、晶型结构不同于普通玉米淀粉。     

非晶颗粒态玉米淀粉的结构特征

采用扫描电子显微镜、光学显微镜、X射线衍射等分析测试方法,以原淀粉为参照,对非晶颗粒态玉米淀粉的颗粒形貌、颗粒大小和结晶程度进行详尽地现察和研究,结果发现,在非晶化处理过程中发生了从内向外爆裂式膨胀而形成大小、深度、位置不同的爆裂孔,并有少量的淀粉颗粒碎片粘附在颗粒的表面上,非晶颗粒态淀粉仍然能够保持颗粒外形,颗粒大小比原淀粉有所增加,不再具有原淀粉颗粒结晶性,整个颗粒呈现无定形结构。     

酶对淀粉颗粒相变性质的影响

采用差示扫描量热仪和Brabender连续黏度仪,系统研究了淀粉颗粒经中温液化酶、葡萄糖淀粉酶和真菌糖化酶作用后的相变性质变化规律。结果表明,随着淀粉酶水解率的提高,淀粉颗粒起始温度、峰值温度、终点温度和吸热焓都呈先上升后小幅下降的趋势,但中温液化酶作用后的吸热焓先降低后上升,说明中温液化酶在较低水解率下作用淀粉颗粒的无定形区的同时也作用结晶区,而葡萄糖淀粉酶和真菌糖化酶主要作用淀粉颗粒的无定形区。连续黏度分析表明,与原玉米淀粉比较,酶处理淀粉糊的峰值黏度均呈下降趋势,起始糊化温度和峰值温度呈上升趋势。     

短直链淀粉纳米颗粒涂层制备超亲水淀粉膜

采用蜡质玉米淀粉为原料,经普鲁兰酶脱支处理,制备短直链淀粉.将短直链淀粉糊化后的溶液,通过膜材浸泡的方式,使淀粉膜表面形成短直链淀粉涂层,再通过4℃的老化处理,制备超亲水淀粉膜.对超亲水淀粉膜的表面形貌、结晶结构、红外光谱及亲水性进行了研究.结果表明,短直链淀粉在淀粉膜表面自组装成了纳米颗粒结构,增加了膜材表面的粗糙度,改善了淀粉膜的亲水性能.当短直链淀粉溶液质量浓度为0.010 g/mL时,可获得水接触角接近于0°的超亲水淀粉膜.     

纳米淀粉的制备与改性

通过交联沉淀法制备了淀粉纳米粒子,并对其进行表面修饰,将苄基取代淀粉葡萄糖单元上的羟基,经FT-IR、1H-NMR、XRD及SEM等对其结构与形态进行表征,得到取代度(DS)约为0.05、且具有一定疏水性的苄基淀粉微细颗粒。纳米淀粉和苄基淀粉微细颗粒的结晶结构不同于原淀粉,结晶度明显降低。它们的形态呈球形,粒径分别为50 nm～100 nm和50 nm～500 nm。所制备的纳米淀粉及苄基淀粉微细颗粒对聚合物基体具有增强、增韧的功能,有望在橡胶等聚合物基体中应用,且苄基淀粉微细颗粒具有双亲性结构,可作为高分子表面活性剂应用。     

非晶颗粒态玉米淀粉的微生物降解特性

采用光学显微分析测试方法,以原玉米淀粉为参照,对非晶颗粒态玉米淀粉在微生物作用下的降解过程进行了详尽地观察和研究．结果发现非晶淀粉颗粒松散的无定形结构以及形成的爆裂孔,大大提高了微生物降解反应活性,在微生物作用下,从淀粉颗粒的爆裂孔开始,沿着淀粉颗粒爆裂孔逐步深入,直至最后将淀粉颗粒完全降解,而原淀粉颗粒具有致密的结晶结构,淀粉颗粒表面没有明显的孔洞,因此生物降解活性在同样条件下,要远远低于非晶颗粒态淀粉。     

高取代度阳离子高直链淀粉的制备及絮凝性能

以高直链玉米淀粉为原料,NaOH为催化剂,2,3-环氧丙基三甲基氯化铵(ETA)为阳离子醚化剂,成功的制备了高取代度阳离子高直链淀粉。分别研究了反应溶剂、反应温度和时间、醚化剂用量、催化剂浓度等因素对产物取代度的影响。实验结果表明,当n(NaOH)/n(ETA)/n(脱水葡萄糖单元AGU)=0.30,反应溶剂为二氧六环和水(V/V=1∶1),n(ETA)/n(AGU)=2,反应温度为60℃,反应时间7h时,制备的阳离子淀粉取代度(DS)可达到1.27。采用FTIR、1 H-NMR和SEM表征了高取代度阳离子高直链淀粉的结构。絮凝实验表明,阳离子高直链淀粉可以作为一种良好的新型絮凝材料。     

Enzyme-aided investigation of the substituent distribution in cationic potato amylopectin starch

The distribution of substituents along the polymer chain in cationic potato amylopectin starch, modified in solution, granular slurry, or dry state, was investigated. The starch derivatives were successively hydrolyzed by different enzymes, followed by characterization of the hydrolysis products obtained by means of electrospray mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). ESI-MS and MALDI-MS were proved to be appropriate techniques for identification of the substituted hydrolysis products, for which there are no standard compounds available. No highly substituted oligomers were found in the hydrolysates, which was taken as an indication of a more or less homogeneous distribution of cationic groups in the amylopectin molecules. Furthermore, from the results obtained it was suggested that the enzymes cleave glucosidic linkages only between unsubstituted glucose units and, preferentially, linkages in sequences containing more than two adjacent unsubstituted units. The determination of the amount of unsubstituted glucose produced from every successive hydrolysis step revealed slight differences between the different starch samples with respect to the homogeneity of the substitution pattern. Among the three samples under investigation, starch cationized in solution was found to have the most and dry-cationized starch the least homogeneous distribution of substituents.     

三聚氰胺甲醛树脂(MF)改性淀粉胶粘剂的研究与应用

以淀粉为主要原料,制备三聚氰胺甲醛树脂(MF),改性淀粉胶粘剂。用红外光谱表征改性的每个阶段,验证其改性机理。X-ray衍射说明了MF对淀粉的结晶度影响不大,MF主要是交联改性的淀粉的无定型区;扫描电镜显示MF对淀粉颗粒形成塑化,改变了淀粉颗粒的表面形貌,通过交联形成网状结构。结果表明,MF改性提高了淀粉胶粘剂的耐水性与稳定性,常温下保存7 d后,其耐水时间、粘度分别为96 h和500 mPa.s。     

苯甲酸改性纳米氧化锌的制备及表征

利用苯甲酸对纳米氧化锌进行表面改性,用亲油化度和吸水率表征改性效果,确定其最佳改性工艺为:苯甲酸质量分数为15%,改性温度为100~105℃,改性时间为2 h。通过X射线衍射、红外光谱、透射电镜、沉降实验和接触角测试,对改性前后的样品进行表征。结果表明,苯甲酸对纳米氧化锌的改性属于化学改性,苯甲酸的羧基与纳米氧化锌表面的羟基发生键合反应,从而改变了纳米氧化锌的性能;改性后的纳米氧化锌样品结晶度高,分散性好,疏水性明显提高。     

淀粉颗粒结构的研究进展

详述淀粉颗粒的形状大小、结晶结构、分子结构、颗粒的微孔特性等最新研究成果，同时对淀粉颗粒及淀粉化学改性的研究方向提出展望。     

Acetylation enhances the tabletting properties of starch

The aim of this study was the evaluation of starch acetate (SA) powders used as tablet excipients. Deformation during powder volume reduction, strain-rate sensitivity, intrinsic elasticity of the materials, and tensile strength of the tablets were examined. Results showed that SA with the lowest degree of substitution (ds) still possessed characteristics of native starch granules. Due to dissolution in synthesis, the properties of higher ds SAs depended on precipitation and drying processes. The acetate moiety, perhaps in combination with existing hydroxyl groups, was a very effective bond-forming substituent. The formation of strong molecular bonds increased, leading to a very firm and intact tablet structure. Small changes existed in compression-induced deformation due to acetylation. Some fragmentation was induced due to the slightly harder and more irregular shape of high-substituted SA particles. The plastic flow under compression was enhanced. Acetylated material was slightly less sensitive to fast elastic recovery in-die, but somewhat more elastic out-of-die. In spite of their superior bonding, SAs under compression behaved similarly to native starches. It was concluded that deformation properties were more the consequence of the molecular chain structure properties of the starch polymer than the effect of the acetate moiety itself. In contrast, the opposite seemed to be the case with the extensive improvement in bond-forming properties.     

Synthesis and characterization of nitrated and aminated poly(phenylene sulfide) derivatives for advanced applications

Nitrated and aminated poly(phenylene sulfide) (PPS) derivatives with different extent of modification were synthesized in a one-pot reaction in suspension. Their substitution degree was determined from both elemental analysis and TGA curves. FT-IR and NMR spectra demonstrated the effectiveness of the functionalization reactions, showing the appearance of bands related to the substituent groups. A progressive reduction in thermal stability was observed as the number of functional groups increased. Aminated derivatives were thermally less stable and exhibited higher solubility in aprotic polar solvents than the corresponding nitrated polymers. DSC thermograms revealed a diminution in the crystallization temperature and a rise in the glass transition with increasing functionalization degree, since the presence of substituent groups inhibits the rotation of consecutive elements of the polymer chain. The level of crystallinity decreased upon increasing chain modification, as evidenced from X-ray diffractograms. The steric hindrance of the substituents disrupts the chain packing, leading to smaller crystals. These derivatives are expected to have applications in electromembranes and as matrix materials for the fabrication of high-performance composites suitable for structural and non-structural components.     

微细化玉米淀粉粒度效应及其流变学行为研究

采用现代粉体机械可制备微细化玉米淀粉。随着淀粉粒度减小,其支链淀粉和直链淀粉糊的特性黏度降低,分子量下降。布拉班德黏度分析表明,微细化玉米淀粉糊化起始温度下降,热糊稳定性增强;在冷却阶段,随着粒度降低,微细化玉米淀粉的凝沉性较原玉米淀粉增强,冷糊稳定性较原玉米淀粉减弱。微细化玉米淀粉糊为非牛顿假塑性流体,其流动性随粒度降低而增加,并显示出一定的粒度效应。