SYNERGISTIC MODIFICATION OF EPDM AND CROSSLINKING AGENT IN IMMISCIBLE BLENDS OF POLYVINYL CHLORIDE WITH LOW DENSITY POLYETHYLENE

The synergism of ethylene-propylene-diene monomer copolymer （EPDM） and dicumyl peroxide （DCP, a crosslinking agent） in low density polyethylene （LDPE）/poly（vinyl chloride） （PVC） blends was investigated. When EDPM and DCP are added to the blends simultaneously, the tensile properties could be improved significantly, especially for the blends with LDPE matrix. For example, incorporation of 10/1 （mass ratio） EPDM/DCP improves the tensile strength of the LDPE/PVC （mass ratio 80/20） blend from 7.9 MPa to 8.5 MPa and the elongation at break from 25% to 503%. Results from selective extraction, phase-contrast microscopy and thermal analysis reveal that the improvement in the tensile properties of the blends with LDPE matrix is principally due to the formation of a fine crosslinking network of the LDPE and EPDM phase. The outstanding modification effect of EPDM is explained by its dual functions： molecular entanglement with LDPE and the enhanced efficiency of DCP in the blends.     

纳米碳酸钙增韧聚氯乙烯复合材料的微结构及界面行为

选择微米、亚微米和纳米级碳酸钙增韧聚氯乙烯复合材料,研究了填料粒度对聚氯乙烯（PVC）复合材料微观结构、材料力学性能及界面行为的影响。结果发现少量CaCO3填充PVC复合材料使体系的加工流动性变好,大粒径颗粒填充PVC复合材料的流动性能更好。纳米CaCO3／PVC复合材料断面出现大量的拉丝结构。采用纳米CaCO3填充PVC可使材料产生脆韧转变,显著提高PVC复合材料的韧性;微米CaCO3对PVC基本上没有增韧作用,拉伸强度随着填充量的增加而下降,而且粒径越大拉伸性能下降的趋势也越大。引入了TPT方程的半经验参数B对不同粒径的CaCO3填充PVC复合材料的界面粘接情况进行定量描述,发现碳酸钙颗粒粒径越小,界面作用越大。     

ZnCl2与POM的合成和结构

ＺｎＣｌ２与ＰＯＭ生成１：２加成物「Ｚｎ（ＰＯＭ）２Ｃｌ２」，Ｃ１２Ｈ１２Ｃｌ２Ｎ４Ｏ６Ｚｎ，晶体必三科晶系，空间群为Ｐ１，晶胞系数为ａ＝１１．７５５（１１）×１０＾－１０ｍ，ｂ＝１２．３５７４（７）×１０＾－１０ｍ，ｃ＝６．５９２（４）×１０＾－１０ｍ，ａ＝１０２。７３２（５）°，β＝９２．０７４（６）°，γ＝１１０．１２４（６０°，Ｖ＝８７６．２×１０＾－３０ｍ，ＭＲ＝４４４．５３，ｚ＝２，ｄ     

HYDROCHLORINATION OF 2,3-ACETYLENIC ACIDS WITH THIONYL CHLORIDE IN DIMETHYLFORMAMIDE

ABSTRACT

The reaction of 2,3-acetylenic acids (1a–d) with thionyl chloride in DMF under mild conditions gave E,Z-3-chloro-2-alkenoic acids (2a–d) or esters (3a–d) depending on treating the reaction mixture with either water or alcohols.     

Ligand-supported palladium-catalyzed cross-coupling reactions of (hetero) aryl chlorides

The introduction of electron rich and sterically hindered ligands has made otherwise inert aryl chlorides and hetero aryl chlorides viable coupling partners in palladium-catalyzed Suzuki-Miyaura, Sonogashira, Stille and other types of cross-coupling reactions. This review gives highlights of cross-coupling of aryl chlorides employing in situ generated palladium catalytic systems.     

Migration of Additives from Poly(vinyl chloride) (PVC) Tubes into Aqueous Media

The stability and migration product of medical PVC tubes plasticized with polyadipates were investigated by ageing in phosphate buffer at pH 1.679 and water at different temperatures. Changes in the PVC tubes were studied by water absorption, weight loss, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The low molecular weight migration product that was released was extracted and silylanized before gas chromatography/mass spectroscopy (GC/MS) identification and quantification. After 70 days, the weight loss was less than 0.5% and only a small amount of adipic acid migrated when a tube was aged at 37°C in water and phosphate buffer (pH 1.679), and at 70°C in water after 56 days. However, when aged at 70 and 110°C, gradual deactivation of heat stabilizer after 21 days of ageing in buffer solution and separation of plasticizer from PVC matrix occurred. When the tube was aged at 110°C, significant degradation of both polyadipates and PVC were observed. Adipic acid and 1,4-butanediol monomers and oligomers of polyadipate were the major migration products from polyadipates in the water ageing solution, while only a relatively high amount of adipic acid was identified as the main product in the buffer ageing solution.     

聚氯乙烯三乙撑四胺负载钯配合物的制备及对Heck反应的催化性能

以聚氯乙烯为原料, 通过胺化反应制得聚氯乙烯三乙撑四胺, 然后用较简单方法得到聚氯乙烯三乙撑四胺负载钯配合物(PVC-TETA-Pd), 利用XPS, TG, DTA和TEM等手段对其进行了表征. 热分析表明PVC-TETA-Pd在室温至250 ℃范围内有很好的热稳定性; TEM分析证实钯在PVC-TETA-Pd中分布比较均匀, 钯颗粒呈球形, 粒径在2～3 nm. PVC-TETA-Pd不需在惰性气体氛围中就能有效地催化丙烯酸、苯乙烯与芳基碘的Heck芳基化反应, 并且在较低的温度(40 ℃)或较少的催化剂用量(0.02%)下, 对Heck反应仍有较好的催化性能. PVC-TETA-Pd便于回收, 且有很好的重复使用性能, 对于碘苯与丙烯酸的反应, 重复使用十二次, 肉桂酸的产率仍达到80.1%.     

Kinetics of the dehydrochlorination of poly(vinyl chloride) in the presence of NaOH and various diols as solvents

The dehydrochlorination of PVC in the presence of NaOH was investigated in different diols. Diethylene glycol (DEG), triethylene glycol (TEG), and propylene glycol (PG) were found to be effective in accelerating the dechlorination of PVC. The dehydrochlorination was promoted in the order TEG > DEG > PG, which was in agreement with the compatibility between PET and the diol. Compatibility resulted in an improved penetration of the PVC particle by the solvent, leading to the acceleration of the dehydrochlorination. The dehydrochlorination of PVC in NaOH/diol followed first-order kinetics, confirming the progress of the reaction under chemical reaction control. The apparent activation energies were 82 kJ mol⁻¹, 109 kJ mol⁻¹, and 151 kJ mol⁻¹ for TEG, DEG, and PG, respectively. The lower the activation energy became the faster the dehydrochlorination of PVC proceeded.     

Thermochemical Study of Coordination of Holmium Chloride Hydrate with Diethylammonium Diethyldithiocarbamate

The complex of holmium chloride hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized via mixing their solutions in absolute alcohol under a dry N2 atmosphere. The elemental and chemical analyses show that the complex has the general formula Et2NH2[Ho(S2CNEt2)4]. It was also characterized by IR spectroscopy. The enthalpies of the dissolution of holmium chloride hydrate and D-DDC in absolute alcohol at 298.15 K o and the enthalpy changes of liquid-phase reactions of the formation of Et2NH2[Ho(S2CNEt2)4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the liquid-phase reaction of the complex formation were obtained, The enthalpy change of the solid-phase complex formation reaction at 298.15 K was calculated by means of a thermochemical cycle.     

聚碱式氯化铝制备实验探索

通过改进的制备方案,在常温下成功制备聚碱式氯化铝。无论在制备方法上还是在净水效果上,改进后的聚碱式氯化铝的制备方案都优于现有教材采用的实验方案。