用DSC研究稀土顺式聚丁二烯的低温结晶与熔融行为

采用示差扫描量热仪研究了稀土顺式聚丁二烯(PB)等温过程的结晶及其熔融行为. 结果表明,在等温结晶的后期存在晶型完善的过程,而且随着等温结晶温度的提高,结晶速率均下降. PB的熔融总是在比等温结晶温度高约2 ℃处开始,而且在10 ℃/min的升温速率下,DSC曲线不仅显示出很宽的熔融温度范围,而且在低温处还出现了小肩峰,说明等温结晶后体系中具有在该升温速率下不同稳定性的晶体. 通过不同温度下的等温结晶曲线,分别采用结晶度趋于零(Xc=0)时的熔点和结晶时间无限长(t-1c＝0)时的熔点,用Hoffman-Weeks方法得到顺式聚丁二烯的平衡熔点T∞m位于9～17.6 ℃之间.     

由结晶动力学评价含结晶聚合物共混物相容性的研究进展

介绍了用结晶动力学分析的方法评价含结晶聚合物共混物的混合状态的基本理论和解析原理,综述了最新研究进展.     

单扫示波极谱法测定食品包装材料中双酚A的研究

研究发现，在0.12mol/L Na2HPO4-KH2PO4(pH7.5)底液中，双酚A于峰电位（Ep)-1.0V(vs.SCE)处产生灵敏的极谱还原波，该波的二阶导数峰电流（ip)与双酚A浓度在2.0-10.0mg/L范围内呈良好的线性关系，检出限为1.0mg/L，萃取后测定，检出限为0.1mg/L。本法操作简便、快速、准确。用于食品包装材料中双酚A含量的测定，结果令人满意。     

氢化物-原子荧光法测定食品容器及包装材料用聚酯树脂及其成型品中的微量锑

为建立简便、快速、高效测定食品包装材料中微量锑的方法,样品用4%乙酸处理后,利用氢化物-原子荧光法检测食品包装材料中的微量锑.结果表明,锑质量浓度在0～20 μg/L范围内呈现良好的线性,回归方程为y =87.284 C-17.440,相关系数r=0.999 9,检出限为0.028 4 μg/L,相对标准偏差RSD为0...     

高效液相色谱法测定纸制食品接触材料中邻苯二甲酸酯的迁移量

以蒸馏水、3％乙酸、10％乙醇、95％乙醇4种食品替代物模拟纸制食品接触材料中10种邻苯二甲酸酯的迁移.以乙腈和水为流动相,Eclipse XDB-C18(4.6mm×150mm,5μm,Agilent)色谱柱分离4种食品模拟物中的10种邻苯二甲酸酯;以C18固相萃取小柱对其进行富集净化,建立了高效液相色谱/二极管阵列检测器测定这10种邻苯二甲酸酯类化合物的方法.结果表明,该10种化合物均在224 nm处有最大吸收波长,其标准曲线的线性相关系数(r2)均大于0.999 9,加标回收率为71％～ 107％,相对标准偏差为0.86％～8.0％,检出限均不大于0.1 mg/kg.该方法灵敏、准确,满足相关法规的限量要求.     

Morphological Changes of Linear,Branched Polyethylenes and their Blends during Crystallization and Subsequent Melting by Synchrotron SAXS and DSC

Summary: The crystalline structure and phase morphology of linear, branched polyethylenes and their blends during crystallization and subsequent melting were investigated, using a combination of differential scanning calorimetry (DSC), and synchrotron small angle X-ray scattering (SAXS). A linear polyethylene (PE1) with weight-average molecular weight (M_w) of 114 000 g/mol, and two branched polyethylene copolymers, containing 4.8 mol% (PE4) and 15.3 mol% (PE10) hexane, with molecular weights of 93 000 g/mol and 46 000 g/mol were used as pure samples. Two blends, PE1-4 and PE1-10, each with a weight ratio of 50/50, were prepared by solution blending. Our results indicate that in PE4 a phase separation within the branched component itself occurred, forming a broad distribution of lamellar thicknesses during the crystallization process. PE10 on the other hand did hardly crystallize because of the high degree of branching. Co-crystallization of both components took place in blend PE1-4 and liquid-liquid phase separation occurred in the melt of PE1-10. Morphological parameters were determined by using Bragg's law and the correlation function, respectively. The detected semicrystalline morphology can be well described by the lamellar insertion mode where thin lamellae develop between thicker primary lamellae. During subsequent heating, lamellae melted in the reversed sequence of their formation. The evolution of the structural parameters as a function of temperature revealed that surface melting began at first, and then the complete melting of stacks occurred until the final melting temperature was reached.     

差示扫描量热法测定除草剂绿麦隆的纯度

研究了用差示扫描量热法(DSC)测定绿麦隆的纯度。该法测定最佳条件为升温速率0.5 K.min-1,样品量2~3 mg,保护气流速20 mL.min-1。用本法测得绿麦隆原药的纯度为98.35%,相对标准偏差(RSD)为0.034%,测定结果与已知纯度相符。并将测定结果与高效液相色谱(HPLC)法进行了比较。该法具有操作简便,样品用量少,准确度和精密度均较高等优点。     

超高效液相色谱-串联质谱法测定食品包装材料中全氟辛烷磺酸盐

建立了超高效液相色谱-串联质谱(UPLC- MS/MS)测定食品包装材料中全氟辛烷磺酸盐(PFOS)的方法.采用乙腈作为溶剂,加速溶剂提取法提取食品包装材料中的PFOS.色谱条件:ACQUITY UPLC BEH C₁₈色谱柱（1.7 μm,2.1 mm×50 mm）;柱温:30 ℃;流动相:乙腈/水,梯度洗脱;流速:0.2 mL/min;经UPLC分离后用多级反应监测(MRM)方式测定.用2个子离子的相对丰度定性, 外标法定量.PFOS在0.005～0.500 μg/mL范围内线性良好(R2=0.999),PFOS的回收率为90.0%～101.6%,相对标准偏差RSD为1.5%～3.5%.方法检出限为0.1 μg/m2(S/N≥3).     

甘露醇纯度的差示扫描量热法测定

使用差示扫描量热法(DSC)对甘露醇纯度进行测定。密封式铝坩埚封装样品,最佳实验条件为升温速率约0.7℃·min-1,样品量约2.5mg,氮气流速为20～40mL·min-1;纯度测定的RSD为0.016,纯度准确测定的下限为98%,通过F检验及t检验,该方法与药典法无显著差异。该方法简便、快速、准确,适合甘露醇等高纯度药品的纯度测定。     

微波消解/电感耦合等离子体质谱法同时测定食品纸包装材料与食品模拟物中24种元素

建立了微波消解/电感耦合等离子体质谱(ICP-MS)同时检测食品纸包装材料及3种食品模拟物(纯水、4%乙酸、10%乙醇)中Li,Be,B,Al,V,Cu,Mn,Zn,Cr,Ni,As,Sr,Zr,Se,Mo,Ag,Cd,Sn,Sb,Te,Ba,Hg,Tl,Pb 24种元素的分析方法,并对元素的迁移行为进行了研究。包装材料样品经微波消解后利用ICP-MS检测;迁移试验中的食品模拟物直接利用ICP-MS检测。在优化实验条件下,24种元素在0~1 000μg/L范围内线性关系良好;方法检出限(MLOD)为0.000 3~0.465 mg/kg;在1.0~1 000 mg/kg加标水平下的平均回收率为90.5%~125.3%;相对标准偏差(RSD,n=3)为1.2%~6.8%。该方法前处理简便、灵敏准确、适用范围广,可用于食品纸包装材料中元素含量的测定及迁移行为的研究,从而为食品纸包装材料的质量监督提供了科学依据。     

Physical Aging of Maltose Glasses as Measured by Standard and Modulated Differential Scanning Calorimetry

The physical aging characteristics of maltose glasses aged at two temperatures below the glass transition temperature, T_g, (T_g-10°C and T_g-20°C) from 5 to 10 000 min were measured by standard differential scanning calorimetry (SDSC) and modulated differential scanning calorimetry (MDSC). The experimentally measured instrumental T_g, the calculated T_g, and the excess enthalpy values were obtained for aged glasses using both DSC methods. The development of excess enthalpy as a function of aging time, as measured by both SDSC and MDSC, was fit using the Cowie and Ferguson and Tool-Narayanswamy-Moynihan models. The change in the T_g values and the development of the excess enthalpy resulting from physical aging measured by the two DSC methods are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

聚酰胺6／聚醚砜共混体系的结晶与熔融行为

聚醚砜（ＰＥＳ）是一种非晶特种工程塑料，具有强度好，使用温度高等特点，但熔体粘度高，加工上有一定困难．聚酰胺６（ＰＡ６）是部分结晶的工程塑料，有很好的强度和耐磨性能．加入适量的ＰＡ６，可显著地降低ＰＥＳ的熔体粘度，且可基本保持ＰＥＳ的原有性能［１］．...     

DSC Studies on Melting and Crystallization of Polyamide 6/Biopol Blends

Blends obtained from Biopol D600G and polyamide 6 reveal in DSC investigations multiphase structure with a distinct crystalline polyamide 6 phase. Due to rapid crystallization of the polyamide 6 the crystallization of the Biopol D600G is retarded. The grade of crystallization of Biopol D600G is lower in the blends than in the pure state, as calculated from the melting enthalpies. Crystallization of polyamide 6 in the blends is faster and results in increasing of the grade of crystallization of polyamide 6 phase comparing to the unblended component. This revised version was published online in August 2006 with corrections to the Cover Date.     

A study of PBT/PC blends by modulated DSC and conventional DSC

Two poly(butylene terephthalate)/polycarbonate (PBT/PC) blends with different formulations were analyzed by modulated DSC (MDSC) and conventional DSC to determine differences in crystallization behavior. A significant difference (30°C in cold crystallization temperature) between the two samples was detectable by MDSC while no significant difference was seen by conventional DSC. That indicatesthe total heat flow from MDSC is not always equivalent to the heat flow from conventional DSC as we have assumed or seen before. The reason has not been fully understood, but may be related to unusual nucleation and crystallization induced by modulation. Alternative conventional DSC methods were developed and compared to the MDSC results.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayThe authors like to thank Drs. Bernhard Wunderlich and Robert Gallucci for helpful discussion, David Shaker and Mary Parsonage for some DSC experiments. Technical support from TA Instruments is also greatly appreciated.     

液相色谱法测定婴幼儿食品包装材料中的脂肪胺

采用新型气流吹扫-微注射器萃取( GP-MSE)技术,用酸化甲醇为提取溶剂,对食品包装材料中脂肪胺进行了提取和富集。以10-乙基-吖啶酮-2-磺酰氯( EASC)为荧光试剂,在60℃、pH 10的条件下,对脂肪胺进行柱前荧光衍生, Hypersil GOLD柱分离,荧光检测的激发波长(λex )和发射波长(λem )分别为262 nm和430 nm。12种脂肪胺检出限为0.4~0.6μg/kg,定量限为1.2~2.1μg/kg,在2.0~2000μg/L浓度范围内,线性相关系数均大于0.998。本方法具有快速、准确、灵敏的特点,用于婴幼儿食品包装材料分析,结果令人满意。     

顶空/气相色谱-质谱联用法测定食品接触材料中5-亚乙基-2-降冰片烯的迁移量

建立了顶空/气相色谱-质谱联用(HS/GC-MS)测定食品接触材料中5-亚乙基-2-降冰片烯(ENB)迁移量的方法,对前处理方法(溶剂提取-直接进样和气液平衡-顶空进样)、顶空平衡温度、顶空平衡时间进行了优化。以水、4%(体积分数)乙酸、50%(体积分数)乙醇和橄榄油作为食品模拟物,样品经食品模拟物浸泡,于顶空气液平衡后进样,经DB-5 MS色谱柱(30 m×0. 25 mm×0. 25μm)分离后,采用选择离子模式进行检测,外标法定量。在优化实验条件下,ENB在0. 1～10 mg/L范围内呈良好的线性关系,相关系数(r)大于0. 999,在0. 1、1. 0、10 mg/L 3个加标水平下,方法的回收率为92. 0%～108%,相对标准偏差(RSD,n=5)为0. 9%～4. 0%,检出限(LOD)为0. 01 mg/kg,定量下限(LOQ)为0. 03 mg/kg。该方法准确、可靠、灵敏度高,适用于食品接触材料中ENB迁移量的测定。     

官能团化聚丙烯对Mg(OH)2/PP结晶与熔融行为的影响

制备了官能团化聚丙烯改性Mg(OH)2/PP复合材料，并用DSC研究了改性PP，Mg(OH)2/PP和改性Mg/(OH)2/PP中PP的结晶与熔融行为，官能团化PP（FPP），丙烯酸（AA）和Mg(OH)2都能提高PP的结晶温度，归结于异相成核作用，AA和FPP加入进一步使Mg(OH)/PP中PP结晶温度提高，但AA用量增加对PP结晶温度无影响。     

差示扫描量热法确定L-脯氨酸的热动力学参数

利用差动热分析仪测得L 脯氨酸的差示扫描量热分析(DSC)曲线,采用普适积分法和微分方程法通过逻辑选择确定了L 脯氨酸相变和热解过程的最可几机理函数,并计算出相应的指前因子和活化能.     

Identification of Polyethylene by Differential Scanning Calorimetry: Application to forensic science

A forensic sample consisting of melt-recrystallized polymers that was recovered from the scene of a fire in a factory was identified by differential scanning calorimetry. The factory commonly used two kinds of film sheets, A and B, made by different manufacturers. It was necessary to decide whether the forensic sample related to material A or B. The forensic sample and reference samples of materials A and B were subjected to infrared spectroscopy and pyrolysis gas chromatograph mass spectrometry measurements, which revealed their polyethylene nature. The thermal behaviour of the samples was examined by differential scanning calorimetry (DSC) and they were found to be blends of two kinds of polyethylenes, low-density polyethylene and linear low-density polyethylene. The samples could be identified and distinguished from each other via the DSC measurements.This revised version was published online in November 2005 with corrections to the Cover Date.     

Differential Scanning Calorimetry Evaluates Relative Proportions and Strength of Acid-Sites in Catalytic Materials and Adsorbents Alumina and Amorphous Silica-Alumina

Abstract

Differential scanning calorimetry (DSC) is employed to evaluate the relative proportions and strength of acid-sites in gammaalumina and amorphous silica-alumina through presorption of tri-ethylamine (TEA) followed by its thermal desorption in the DSC equipment. From the data obtained, total acid-sites in silica-alumina is found to be 2.3 times as large as those present in gamma-alumina, and 5–5% of total acidity in alumina is of Bronsted type whereas in silica-alumina this type comprises 28.9%' The Bronsted acidity strength in alumina and silica-alumina is identical although greatly different in quantity. Lewis acidity in silica-alumina is significantly stronger than that in alumina.