熔纺用离子液体增塑二醋酸纤维素结构与性能研究

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF_4)为二醋酸纤维素(CDA)增塑剂,在抗氧剂1010和亚磷酸三苯酯(TPPi)存在时熔融挤出造粒制备纺丝切片,进而熔融纺丝制备二醋酸纤维。研究了熔融挤出温度对CDA分子量的影响,以及熔融纺丝前后CDA化学结构和热性能的变化;进一步研究了二醋酸纤维的形貌以及牵伸对二醋酸纤维力学性质与结晶度的影响。结果表明:熔融温度对CDA分子量影响较大,熔融挤出温度从170℃增加到200℃时,CDA分子量由6.0×10~4g/mol降低至2.0×10~4g/mol;CDA增塑熔融纺丝前后化学结构并未发生明显变化,但其玻璃化转变温度因热降解而有所下降;对切片熔融纺丝可以得到强度为1.06 cN/dtex的二醋酸纤维,其断裂强度随着牵伸倍数增加而增加,结晶度也随之增加。     

渗透脱水对芒果解吸等温线和玻璃化转变温度的影响

为提高芒果贮藏期品质,试验采用GAB模型和Gordon-Taylor方程分别拟合了芒果吸附等温线与玻璃化转变温度等试验数据,并且研究了经渗透脱水处理后,芒果玻璃化转变温度及解吸等温线的变化规律。试验结果表明:经渗透脱水处理后的芒果解吸等温线仍满足GAB模型,当水分活度增大时,平衡干基含水率也不断增大;在不同的水分活度区间,渗透溶液种类对芒果解吸等温线的影响显著;芒果玻璃化转变温度随着渗透脱水后固形物湿基质量分数的减少而降低,经过葡萄糖、蔗糖和麦芽糖等渗透处理芒果后,水分子的塑化作用逐渐变弱。     

基于动态机械分析仪的馒头玻璃化转变温度测定条件的研究

食品的玻璃化转变温度是控制食品质量和稳定性的关键。食品在玻璃化转变温度下进行保存,可最大限度保存其原有色、香、味、形及营养成分,从而延长食品保存期,提高食品保存过程中质量。基于此,研究用动态机械分析仪(DMA)对馒头的玻璃化转变温度进行了测定。结果表明:在不同测定条件下得到的馒头玻璃化转变温度不同。在振幅变化,其他测定条件不变时,馒头的玻璃化转变温度随振幅的增大而减小;在温度变化速率改变,其他测定条件不变时,馒头的玻璃化转变温度随温度变化速率的增大而增大。综合得出在振幅20μm,温度变化速率2℃/min下测得的馒头玻璃化转变温度较客观准确。因此,最佳测定是其他条件不变,振幅20μm,温度变化速率2℃/min。     

面团的玻璃化储存

由于面团在冷冻储存过程中受到结晶与再结晶的影响,产生结构松弛和水份迁移,品质显著下降。实现面团的玻璃化储存是解决问题的最佳方案。通过加入合适添加剂,可提高面团玻璃化转变温度,实现一般冷冻储存温度（-18℃）下的面团玻璃化储存。分析了各种玻璃化转变温度测定方法和添加剂在提高面团玻璃化转变方面的应用。     

多孔木素/醋酸纤维素基微纳米碳纤维的制备及功能化应用

采用静电纺丝的方法,通过调整木素与醋酸纤维素的质量比来制备具有多孔结构的前驱体纤维,然后经预氧化和碳化得到具有不同孔隙结构的木素/醋酸纤维素基微纳米碳纤维,并对制备所得的碳纤维进行傅里叶变换红外光谱、热重分析、场发射扫描电子显微镜、氮气吸附脱附以及亚甲基蓝吸附等表征。结果表明,木素与醋酸纤维素纺丝混合性良好,混纺之后前驱体纤维热稳定性与玻璃化转变温度均优于醋酸纤维素;当醋酸纤维素与木素质量比为8:2时,制备的多孔微纳米碳纤维直径较细,孔洞分布均匀,比表面积最大为173.42 m~2/g,水接触角最大为129.3°,亚甲基蓝吸附量最优,吸附量达到49.30 mg/g,且循环使用7次之后其亚甲基蓝吸附量仍能达到初次使用的95%以上。     

基于玻璃化转变及流动特性的枸杞粉贮藏稳定性研究

本文基于水分活度和玻璃化转变理论,分析了枸杞粉的吸附等温线及玻璃化转变温度,通过构建状态图确定枸杞粉具有良好贮藏稳定性的临界水分含量;通过测试不同水分含量的枸杞粉的流动特性表征体系玻璃化转变的变化。结果表明:枸杞粉的吸附等温线呈"J"型,GAB模型为描述其水分吸附特性的适宜模型;枸杞粉的玻璃化转变温度随水分含量的升高而降低,以LB1枸杞粉为例,当干基含水率从0.133 g/g增加到0.530 g/g时,玻璃化转变温度从10.82℃降至-59.71℃。状态图表明,4种枸杞粉(LB1～LB4)干基含水率分别低于0.0833,0.0906,0.0992,0.1059 g/g时,在25℃下可稳定贮藏。宏观流动特性结果表明:随着枸杞粉水分含量的增加,粒径越大,越易发生玻璃化转变,粒径越小越有利于贮藏。     

食品添加剂对面团玻璃化转变温度的影响

实现食品的玻璃化贮藏是提高食品质量的有效手段。本研究利用差示扫描量热仪探讨了适用于面团玻璃化转变温度测量的扫描程序、研究了水分含量及若干食品添加剂对面团玻璃化转变温度的影响规律。结果表明,多次扫描法是一种可行的面团玻璃化转变温度的测量方法;水分添加量对面团的玻璃化转变温度有明显影响。在本研究的范围内,面团的玻璃化转变温度随面团水分含量的增加而明显下降。食品添加剂对面团的玻璃化转变温度有显著影响。添加抗坏血酸、海藻糖及明胶时,均可不同程度的使面团的玻璃化转变温度有所升高,这对于在现有储存条件下(-18℃)实现面制品的玻璃化保存,提高速冻面制品的稳定性,改善速冻面制品的质量有重要的应用价值。     

粉丹竹SCMP木素结构的2D NMR分析

采用二维核磁共振(2D NMR)波谱对粉丹竹磺化化学机械浆(SCMP)木素结构进行了分析。研究结果表明,粉丹竹SCMP的木素是由愈创木基型(G)、紫丁香基型(S)和对-羟基苯基型(H)等三种木素结构单元组成;木素结构的连接方式主要是β-O-4′醚键结构,还有树脂酚结构(β-β′,α-O-γ′,α′-O-γ)、苯基香豆满结构(β-5′,α-O-4′)、二苯并-二氧桥-松柏醇结构(5′-5″,α-O-4′,β-O-4″)和β-1′结构等;H型木素主要以对-香豆酸的形式与β-O-4结构木素侧链的γ位羟基形成酯键。     

温湿度对棉纤维质量的影响

棉纤维在储存期间的质量变化,主要是棉纤维自身的运动或生理活动的结果。棉纤维体的运动或生理活动的快慢、旺盛或迟滞,与储存环境密切相关。在环境诸因素中,温度和湿度最为重要。本文就温湿度的变化对棉纤维质量的影响作一分析,供大家参考。一、棉纤维含水的原因棉纤维的主要成分是纤维素,含水亲水基团的羟基。棉纤维中纤维素组织结构不匀,存在着结晶区和无定形区。结晶区的纤维素分子链排列整齐,分子间距小,结合力强,水分子不易进入。纤维素的无定形区域的比例越大,则吸收水分子也越容易。棉纤维素有很多微小的细孔和缝隙,具有…     

洋葱精油微胶囊制备工艺优化及其品质分析

为得到包埋效果好、品质优良的洋葱精油微胶囊,采用喷雾干燥法,研究壁材种类、芯材-壁材用量比和固形物用量对微胶囊包埋率的影响及在扫描电子显微镜下的形貌、感官性状、包埋度、含水率、溶解度、堆积密度、贮藏稳定性等。结果表明：在复合壁材为阿拉伯胶＋β-环糊精（质量比4∶3）、芯材-壁材用量比1∶4（mL/g）、固形物用量20%的条件下,洋葱精油微胶囊包埋率为92.35%;扫描电子显微镜结果显示微胶囊表面连续,呈光滑的球形;且微胶囊具有良好的感官性状,粉末均匀不黏壁,能够有效掩盖洋葱精油的辛辣刺激性气味,易于被消费者接受;在最佳制备条件下微胶囊的包埋度、含水率、溶解度、堆积密度、玻璃化转变温度分别为21.32%、3.69%、97.56%、0.786?g/cm3、46.35?℃,表明微胶囊易于溶解,含水率低,玻璃化转变温度高于一般贮藏温度。因此,最佳制备条件下微胶囊产品品质较优,具有良好的贮藏稳定性及市场接受度。     

Empirical,thermodynamic and quantum-chemical investigations of inclusion complexation between flavanones and (2-hydroxypropyl)-cyclodextrins

The inclusion complexation of (2-hydroxypropyl)-cyclodextrins with flavanones was investigated by phase solubility measurements, as well as thermodynamic and quantum chemical methods. Inclusion complexes were formed between (2-hydroxypropyl)-α-cyclodextrin (HP-α-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD), (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD) and β-cyclodextrin (β-CD) and four flavanones (naringenin, naringin, hesperetin and dihydromyricetin) in aqueous solutions and their phase solubility was determined. For all the flavanones, the stability constants of their complexes formed with different CDs followed the rank order: HP-β-CD (MW 1540) > HP-β-CD (MW 1460) > HP-β-CD (MW 1380) > β-CD > HP-γ-CD > HP-α-CD. Experimental results and quantum chemical calculations showed that the ability of flavanones to form inclusion complex with (2-hydroxypropyl)-cyclodextrins was determined by both the steric effect and hydrophobicity of the flavanones. For flavanones that have similar molecular volumes, the hydrophobicity of the molecule was the main determining factor of its ability to form inclusion complexes with HP-β-CD, and the hydrophobicity parameter Log P is highly correlated with the stability constant of the complexes. Results of thermodynamic study demonstrated that hydrophobic interaction is the main driving force for the formation process of the flavanone–CD inclusion complexes. Quantum chemical analysis of the most active hydroxyl groups and HOMO (the highest occupied molecular orbital) showed that the B ring of the flavanones was most likely involved in hydrogen bonding with the side groups in the cavity of the CDs, through which the inclusion complex was stabilised.     

超临界CO2流体处理时间对二醋酯纤维结构与性能的影响

为将超临界CO₂流体应用于二醋酯纤维的功能化加工,赋予二醋酯纤维高附加值,借助扫描电子显微镜、傅里叶红外光谱仪、X射线多晶衍射仪、热重差热分析仪、万能材料试验机探讨了超临界CO₂流体处理时间对二醋酯纤维表观形态、化学结构、聚集态结构及热性能和拉伸断裂性能的影响。结果表明:经超临界CO₂流体处理60、90、120 min后,二醋酯纤维表面颗粒状杂质被去除,其分子链排列规整度下降,结晶度由未处理纤维的39.41%分别下降至35.33%、31.57%、36.10%,纤维断裂强力呈先下降后增加趋势;当处理时间为120 min时,二醋酯纤维分子链间氢键作用强度略微降低,其熔点基本不变,高温下纤维质量损失率由未处理纤维的89.52%增加至95.66%。     

棉纤维表面氨基硅的膜形貌及其定向排列方式

 用场发射扫描电镜FE-SEM和光电子能谱仪XPS研究了天然棉纤维表面氨基硅——N-β-氨乙基-γ-氨丙基聚二甲基硅氧烷(ASO-1)的膜形貌及其定向排列成膜方式。结果发现,在观察尺寸WD≥200 nm的条件下,ASO-1在棉纤维表面形成的硅膜呈相对均匀的平滑形貌。XPS定量分析表明,在ASO-1处理后的棉纤维表面,大多数N原子被固定在硅膜与纤维的界面。这表明氨基硅在棉纤维表面的定向排列成膜方式为:硅甲基朝外伸向空气,Si—O偶极键及极性氨基指向纤维界面。     

Distribution of Water in Fresh Cod

Low-field ¹H nuclear magnetic resonance (NMR) transverse relaxation was used to measure water mobility and distribution of water in fresh cod fillets. The NMR relaxations were analysed with the so-called SLICING method giving uni-exponential profiles from which the transverse relaxation time (T₂-values) and the relative sizes of the water populations were calculated. Two water populations with the T₂-values of 50 and 94 ms were obtained. The shortest relaxation time was primarily found near the head, and water with the longest relaxation time was primarily found near the tail. This variation can be explained by the smaller muscle cells and muscle fibers in the tail, which may influence the distributions of water into the different pools. The amount of one of the water populations was correlated to the overall water content with a correlation coefficient of −0.94.     

Biodegradable packages development from starch based heat sealable films

Heat sealing capacity of native and acetylated corn starch based films was evaluated to develop biodegradable packages, such as bags. Thermo-mechanical properties were analyzed since they condition their handling and applications. Acetylated starch addition reinforced 80% sealing resistance of starch films. Unplasticized heat-sealed films presented adhesive failures while those containing glycerol showed a rupture near the zip. Unplasticized films exhibited a single relaxation (at around 60 °C), detected by DMA and conventional DSC, which was not affected by the acetylated starch content. DMA curves of plasticized films showed two relaxations, one close to −50 °C associated to the glass transition of the plasticizer-rich phase, and other around 60 °C, attributed to the starch-rich phase. This last transition was also observed using MTDSC. Glycerol addition decreased the relaxation temperature of the starch-rich phase being this effect more marked in native starch films, about 28%. A relation between film composition, microstructure, mechanical behavior, and dynamic mechanical thermal analysis was established.     

绿松石颜色成因及分级研究现状

绿松石是一种含水的铜铝磷酸盐矿物,纯净状态下呈天蓝色,因常见复杂类质同象而呈现出丰富多变的颜色外观.绿松石颜色成因可由晶体场理论解释,其天蓝色由Cu2+配位八面体的局域对称性及其在晶格中的结构位置决定;Fe3+和V3+的综合作用导致蓝色绿松石中绿色调的出现;Fe3+含量的增多会使得蓝色绿松石向土黄、棕色转变.绿松石中存在氢键较强的羟基(Al-OH)、氢键相对较弱的[Cu(H2O)4]2+和充填在孔隙或微裂隙中的吸附水,其中羟基和结晶水的热损失会对绿松石颜色产生破坏性的影响,而吸附水含量的增加仅对绿松石颜色的明度和饱和度产生积极作用.绿松石结构致密性影响着绿松石吸附水的赋存,疏松绿松石吸水前后的色差大于致密绿松石吸水前后的色差.目前针对绿松石颜色分级的研究方法可分为理论建模型和规律总结型两类,前者基于CIE 1976 L*a*b*颜色体系,以L*、a*和b*颜色参数为独立变量进行聚类分析和判别分析,将单一色调内的绿松石颜色分成差异性极显著的不同类别,从而根据明度和彩度进行具体级别的描述;后者基于HSB表色体系,实现绿松石颜色空间内的可视化表征,总结绿松石分布规律并结合肉眼观察特征,并以色相分级、明度分级和饱和度分级构成绿松石颜色分级的全部内容.     

Adsorption and photocatalyzed oxidation of methylated arsenic species in TiO2 suspensions

Monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) are used as herbicides in the agriculture industry. We have demonstrated that MMA and DMA are readily degraded upon TiO2 photocatalysis. DMA is oxidized to MMA as the primary oxidation product, which is subsequently oxidized to inorganic arsenate, As(V). The adsorption of MMA and DMA on Ti02 surface was measured as a function of initial arsenic concentration and solution pH. The pH of the solution influences the adsorption and photocatalytic degradation to a similar degree, due to the speciation of the arsenic substrates and surface charge of TiO2 as a function of pH. The mineralization of MMA and DMA by TiO2 photocatalysis follows the Langmuir-Hinshelwood kinetic model. Addition of tert-butyl alcohol, a hydroxyl radical scavenger, during TiO2 photocatalysis dramatically reduces the rate of degradation, indicating that *OH is the primary oxidant. For dilute solutions, TiO2 may also be applicable as an absorbent for direct removal of a variety of arsenic species, namely As(III), As(V), MMA, and DMA, all of which are strongly adsorbed, thus eliminating the need for a multistep treatment process.     

水刺固结原理的研究

介绍了水刺非织造布工艺技术的原理是以“水”为主要的加工工具,利用高速运动的“水针”将纤维互相缠结,“水针”对纤维固结的过程也就是水刺工艺的关键所在。     

THERMAL AND DYNAMIC-MECHANICAL PROPERTIES OF FROZEN WHEAT DOUGHS WITH ADDED SUCROSE,NaCl, ASCORBIC ACID,AND THEIR MIXTURES

The effects of sucrose, NaCl, and ascorbic acid on the physical state of wheat dough at sub-zero temperatures were investigated using Differential Scanning Calorimetry (DSC) and Dynamic-Mechanical Analysis (DMA). The DSC thermograms were obtained for annealed samples by scanning from ?80 to 10°C at 5°C/min. Added sucrose and NaCl decreased the onset of ice melting of doughs, and they were found at ?26°C. Added sucrose and NaCl increased the relative amount of unfrozen water in doughs, while added ascorbic acid had not noticeable effects. DMA measurements were made for annealed samples at a heating rate of 1°C/min from ?150 to 10°C. The loss modulus, G″, of DMA showed an α-relaxation (glass transition), two low temperature relaxations (β and γ), and melting of ice in all doughs with added ingredients.     

硫酸钠在低带液轧-焙-蒸活性染料染色中的作用

为探究加入硫酸钠后低带液轧-焙-蒸活性染料染色效果更好的原因,通过分子动力学模拟的方法,建立纤维表面染液层模型,研究在有无硫酸钠的条件下焙-蒸过程中体系水分蒸发、染料和离子分布情况,计算了数密度和径向分布函数。结果表明:硫酸钠在低带液轧-焙-蒸染色过程中存在保水作用,且在碱处理后,即纤维素糖环上的羟基变成氧负离子之后,保水作用更明显;硫酸钠的加入产生了纤维素氧负离子-钠离子-硫酸根离子-钠离子的稳定、定向排列的多电位层,能够有效锁住纤维表面的水分,为染料和纤维提供更好的反应环境,而且能够防止染料随着水分子在高温下发生解吸附、泳移以及水解反应。