对-乙酰氧基苯甲酸与聚对苯二甲酸乙二醇酯共缩聚反应及醚键形成的研究

监测了对-乙酰氧基苯甲酸与聚对苯二甲酸乙二醇酯(PET)共缩聚反应过程中1HNMR图谱及特性粘度的变化,对乙酰氧基酯交换反应及乙酰脂肪酯的反应活性进行了研究。并研究了以低分子量PET或对苯二甲酸二乙二醇酯为原料时反应中醚键的形成及其进入共聚酯链的规律性。     

BICENTRAL POLYMER SUPPORTED PHASE TRANSFER CATALYST POLYSTYRENE—SUPPORTED POLYETHYLENE GLYCOL AND PYRIDINIUM SALT

A bicentral polymer-supported phase transfer catalyst,polystyrene-supported polyethylene glycol and pyridinium salt(PS-Py-PEG-400),synthesized with chloromethylated polystyrene as supporter on which PEG and pyridinium salt were immobilized successively.Its catalytic activity was tested for the reaction of solid potassium acetate and benzyl bromide by GC analysis.It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.     

Poly(ethylene glycol)-supported Piperazine——Synthesis and Application in Knoevenagel Condensation

A soluble,poly(ethylene glycol)-supported piperazine catalyst was prepared.This soluble catalyst efficiently catalyzes the Knoevenagel condensation of various aromatic aldehydes with diethyl malonate or ethyl acetoacetate in a homogeneous phase to afford the desired alkenes in good purity and yield with a facile work-up process.It was found that the polymer reagent could be repeatedly used at least four times without the too much loss of activity.The catalyst has shown a good activity,stability,and recyclin...     

涤纶化学降解单体产物的高效结晶提纯研究

为了解决废旧涤纶(PET)纺织品乙二醇醇解法循环利用中存在的醇解产物对苯二甲酸二乙二醇酯(BHET)纯化困难的问题,通过研究BHET晶体的独特的相变性质,发展了BHET纯化新技术.实验结果表明,对结晶的、醇解反应产物BHET使用减压升华操作,在1.33 kPa,130℃的条件下,可获得纯度达99.7%,收率达86.4%,白度(L^*值)达99.8的纯化BHET.回收所得的BHET可再缩聚制备再生PET.该再生PET在相同条件下与由石油基BHET缩聚所制得的PET具有类似的性质,包括白度、分子量及分子量分布等.本文还验证了该种醇解法回收废旧涤纶纺织品的技术的普适性：考察各种含有不同成分及颜色的涤纶纺织品样品的醇解行为及产物分离纯化效果.所研究的BHET纯化方法步骤短、产物纯度高、不额外使用有毒化学试剂,并有效地克服了粉末状BHET在加热纯化时容易发生缩聚的关键难题,为高品质回收废旧涤纶纺织品提供了一种新的路径.     

竹纤维的接枝改性及其在聚对苯二甲酸乙二醇酯/竹纤维共混物中的应用

通过接枝反应制备BF-g-SMA相容剂,增容聚对苯二甲酸乙二醇酯/竹纤维(PET/BF)共混物,探究BF-g-SMA相容剂用量和PET/BF质量配比对PET/BF共混体系的影响,并通过红外光谱、扫描电镜及差示扫描量热仪及熔融指数仪器进行性能表征。结果显示,相容剂用量为6%和竹纤维用量为20%下,增容效果最好。此时,PET/BF共混物的熔融指数最大、密炼时扭矩最小,流动性最好;共混物的表面较光滑、竹纤维与聚合物基体的结合较好;熔融温度、结晶温度、结晶焓及结晶度较适宜。     

发射机冷却系统在冬季的维护

本文主要介绍电视发射机的冷却系统在冬季前后的维护保养。     

铜基催化剂的制备方法对草酸二乙酯加氢反应的影响

草酸二乙酯加氢性成乙二醇的反应过程中，所用的铜基催化剂是由Ｃｕ（ＮＯ３）２与硅溶胶凝法制得的。本文考察了该催化剂的ＴＰＲ特性，结果表明，随着催化剂中Ｃｕ／ＳｉＯ２值的增大，其ＴＰＲ主峰ＴＭ峰温有所升高，这意味着催化剂的还原温度随Ｃｕ／ＳｉＯ２值的增大而提高。用ＸＲＤ和ＸＰＳ等手段对该催化剂还原后铜的含量及价态进行了考察，表明用胶凝法制备的铜基催化剂，还原后存在Ｃｕ＾ｏ和Ｃｕ＾＋两种价态。结合活性评     

取向PET薄膜偶极热松弛的研究

用纵拉、先纵后横、纵-横-纵等拉伸方式得到了各种平面取向程度的PET薄膜。短路热释电流温谱显示α峰随平面取向度增大向高温线性移动。被冻结的大分子主链链段偶极热松弛活化能随反式构象含量增大呈线性下降。热松弛时间常数则随反式构象含量增大而增长。     

An Alcohol-templated Borate Based on [B14O20（OH）6]4- Polyborate Anions

A new borate [H2EG][B7O10（OH）3] （1） based on [B14O20（OH）6]4- polyborate anions has been solvothermally synthesized in the presence of H2EG as a template （EG = ethylene glycol）. The structure was determined by single-crystal X-ray diffraction and further characterized by FFIR, elemental analysis and thermogravimetric analysis. Compound 1 crystallizes in the triclinic system, space group Pi, with a = 8.5095（4）, b = 8.8694（4）, c = 10.0756（4） A, a = 95.094（2）, β = 96.936（2）, γ = 116.844（2）°, V = 664.66（5） A3. The structure of 1 consists of [B14O20（OH）6]4- moiety, which could be regarded as the largest isolated polyborate anion so far. The anions are interlinked via hydrogen bonding to form a 3D supramolecular network, whereas the diprotonated [H2EG]2＋ are filled in the free space of inorganic borate network and interact with the inorganic framework by extensive hydrogen bonds. It is noteworthy that the EG acts not only as a solvent, but also as a template.