季戊四醇和双季戊四醇气相色谱分析方法研究

应用柱前衍生-气相色谱法分离并测定了反应混合物中同存的季戊四醇(MPE)和双季戊四醇(DPE)、衍生化反应系在120℃加热的封闭试管中进行。将含有MPE及DPE的试样与甘露醇,4-二乙氨基吡啶及乙酸酐和吡啶的混合溶液置于此试管中,密封,加热并每隔10 min摇动溶液一次直至溶液成澄清液。此时MPE,DPE及甘露醇均生成乙酸酯衍生物,取此澄清溶液0.2 mL进行色谱分析,分离及测定时采用内装3%OV-17+3%XE-60及过180~150μm 101AW-WS的不锈钢管(1 m×3 mm)作色谱柱。应用此方法分析了不同含量的4个试样,所得结果的RSD值,测MPE时小于0.21%,测DPE时小于0.14%。测定值与标准值之间的偏差均小于0.7%。     

Metal dicarboxylates as thermal stabilizers for PVC

Different metal dicarboxylates such as calcium glutarate, zinc glutarate, calcium sebacate and zinc sebacate were investigated in this paper as thermal stabilizers (without and with calcium stearate and pentaerythritol as costabilizers) of poly(vinyl chloride) (PVC). The thermal stability of the PVC films was determined by two different methods which are visual color comparison and measurement of HCl release from heated pellets. Both zinc dicarboxylates and calcium dicarboxylates exhibited good thermal stability. With respect to stabilizing performance, zinc glutarate (ZnGa) was more effective than zinc sebacate (ZnSe), particularly in the presence of a large amount of pentaerythritol. Similarly, calcium glutarate (CaGa) was more effective than calcium sebacate (CaSe). And the relative order of stabilizing effectiveness of metal dicarboxylates was as follows: CaGa > CaSe > ZnGa > ZnSe. Moreover, the Ca-Zn complex thermal stabilizer and the Pe-Zn complex thermal stabilizer were also studied. It was found that no more than 20% of the zinc compound exhibited better stabilizing performance.     

Effect of pentaerythritol and organic tin with calcium/zinc stearates on the stabilization of poly(vinyl chloride)

The stabilization effect of calcium and zinc stearates (CaSt₂/ZnSt₂) combined with pentaerythritol (PeE) and organic tin on poly(vinyl chloride) was investigated. The results show that the addition of calcium/zinc stearates combined with PeE and organic tin can improve thermal and colour stability of poly(vinyl chloride) in both static and dynamic tests. Mechanisms for improving stability of PVC are also discussed. The increase of stabilizing effectiveness of calcium/zinc stearates is ascribed to the synergistic effect between CaSt₂/ZnSt₂ and PeE and the interaction between organic tin and double bonds formed during the degradation of PVC. There is no synergistic action between organic tin and PeE or organic tin and calcium/zinc stearates.     

季戊四醇丙烯酸酯的宽孔(530μ)弹性石英毛细管柱气相色谱分析

本文报道的方法具有快速、简便、准确的特点。用解联立线性方程求校正因子的方法,在缺少纯标样的场合可推荐应用。对高沸点、强极性体系分析本文有考考价值。     

高效液相色谱法测定季戊四醇和二季戊四醇

建立了分离测定季戊四醇和二季戊四醇的反相高效液相色谱法。在C18烷基键合相分离柱上,以乙腈∶水[5∶95(V/V)]为流动相,流速为1.0ml·min-1。紫外检测波长为196nm,方法的相对标准偏差季戊四醇和二季戊四醇分别为2.4%和4.5%。加标回收率分别为96.36%和95.78%。方法用于二季戊四醇生产工艺条件的选择和反应液浓度的控制分析。     

Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography

This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate-ethylene dimethacrylate (PEDAS-EDMA) monolithic column has been investigated for an optimised condition to separate alpha-, beta-, gamma- and delta-TOHs, and alpha-tocopherol acetate (TAc). The PEDAS-EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the beta- and gamma-isomers which are not easily separated by standard C8 or C18 particle-packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS-EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic beta- and gamma-isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.     

沉淀聚合制备聚(季戊四醇三丙烯酸酯-苯乙烯)单分散微球及其形成机理

以季戊四醇三丙烯酸酯(PETA)作交联剂,苯乙烯作共聚单体,偶氮二异丁腈作引发剂,在乙醇或其与水的混合溶剂中沉淀聚合制备了交联聚合物微球.研究了反应时间、交联剂用量以及溶剂中水含量对聚合过程及微球的影响.结果表明当PETA用量在单体质量的5%-35%之间且反应时间不低于6h时可制得单分散聚合物微球.当PETA用量低于20%时,所得微球的粒径随PETA用量的增加逐渐减小,粒径分布逐渐变窄;此后继续提高PETA用量,微球粒径又逐渐增大,粒径分布逐渐变宽.向反应介质中加入水,可明显提高微球产率及单体转化率,但其体积分数达30%时,所得微球分散性变宽.在此基础上对微球的形成机理也进行了讨论.     

高温下季戊四醇晶体的结构和振动性质的分子动力学模拟(英文)

通过分子动力学研究了季戊四醇晶体在温度高达500K范围内的结构和振动性质.考察了季戊四醇晶体的晶格参数和分子构型等随温度变化情况,相对晶格常数a来说,晶格常数c容易被压缩.发现C-C,C-H和C-O键随温度的变化较大,这意味着在分解过程中这些键可能较敏感,即最先断裂可能性较大.研究了季戊四醇晶体在不同温度下的振动,发现大部分频率随温度的升高而降低.     

Properties and hydrolysis of PLGA and PLLA cross-linked with electron beam radiation

Radiation has been used as a processing tool to modify the properties of polymers. The aim of this study is to understand how electron beam radiation, together with pentaerythritol tetraacrylate (PTTA) as a tetra-functional monomer, can alter the properties (i.e. thermal and mechanical) and hydrolysis rates of PLGA and PLLA. The effects of radiation dose and PFM concentration on the physical properties of the polymers were investigated. The results showed that upon irradiation PLGA and PLLA cross-linked, and an increased in gel content was observed. Glass transition temperature (T_g) and mechanical properties of the polymers also increased. Cross-linked PLGA and PLLA samples were found to retard hydrolytic degradation. The mechanical properties of these polymers were also unaffected by hydrolysis. In summary, PLGA and PLLA cross-linked with PTTA were found to have enhanced mechanical properties and were able to retard hydrolytic degradation.     

Structure-property relationship in intumescent polymeric formulations containing waste zeolite-based material as a synergistic agent

The synergistic effect between spent oil-cracking catalyst (FCC catalyst) and an ammonium polyphosphate/pentaerythritol intumescent mixture was evaluated for various polyethylenic matrices. The mixtures were rated according to the UL-94 standard and evaluated by limiting oxygen index (LOI) testing, Thermogravimetric analysis and cone calorimetry. LOI results demonstrated a synergistic effect of the catalyst with the intumescent formulation in polyethylene, poly(ethylene-co-butyl acrylate), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl acrylate-co-maleic anhydride). This synergistic effect also led to lower rates of heat release, total heats evolved and fume emissions, as observed by cone calorimetry. The nature of the polymeric matrix appears to influence the extent of the synergistic effect and, among the comonomers studied, butyl acrylate seems to benefit the most from catalyst addition in terms of fire-retarding properties. Apparently, the amount of comonomer affects the LOI results, although its influence as measured by other tests is not clear.