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1.
硬脂酸稀土对PVC热稳定效能的递变   总被引:2,自引:0,他引:2  
研究了钪、钷外其他稀土金属硬脂酸皂对PVC热稳定作用. 结果表明 它们均属长期型热稳定剂, 与少量硬脂酸锌并用可有效改善其抑制PVC初期着色的效能;不同硬脂酸稀土与硬脂酸锌并用稳定的PVC具有相似的初期色相, 但中、长期热稳定性不同, 其中镧系金属皂的中、长期热稳定性随原子序数呈现明显的奇偶效应递变规律性;硬脂酸稀土具有类似于碱土金属皂的热稳定作用机制.  相似文献   

2.
稀土PVC热稳定剂作用模式及协同效应研究   总被引:3,自引:0,他引:3  
稀土化合物对PVC良好的稳定作用,并存在广泛的协同效应。探索了一种计算机辅助研究稀土PVC热稳定剂作用模式及效应的方法,可以预测稳定剂的稳定效能。结果表明,在稀土硬脂酸盐及同类稳定剂中,曲线回归方程参数有效地反映了热稳定剂类型的差别;引入协同效应函数,不仅提高了回归方程的可信度,而且能反映协同效应的形成规律。  相似文献   

3.
为了进一步研发性价比高且"无铅化"的稀土复合热稳定剂,研究了系列硬脂酸轻稀土盐(镧/铈/镨/钕/钐/铕/混合)与其他常用PVC热稳定(助)剂的复配效果。通过刚果红试纸法、红外光谱分析(FT-IR)、转矩流变仪等探究了复合热稳定剂对PVC性能的影响。结果表明:复合热稳定剂配方为硬脂酸轻稀土盐0.7~1.0份、硬脂酸锌0.8~0.9份、β-二酮0.3~0.6份和季戊四醇0.8~0.9份。将3份复合热稳定剂添加到100份PVC树脂中,静态及动态热稳定时间延长至100和35 min左右;动态热稳定性能和力学性能优于市售钙锌热稳定剂,与市售铅盐较接近。红外光谱分析表明复合热稳定剂可在加热初期减缓PVC氧化降解,较好地抑制初期着色,对PVC性能影响顺序为:镧组钕组混合组铈组镨组钐组铕组。  相似文献   

4.
合成了月桂酸镧/铈/钕,分别与硬脂酸钙、季戊四醇复配得到了硬质PVC用月桂酸稀土复合热稳定剂。采用刚果红法、转矩流变仪、动态力学谱仪等考察其对PVC热稳定性、流变性能、力学性能的影响,利用红外光谱初步探讨了其热稳定机制。结果表明:稀土复合热稳定剂中月桂酸镧(铈/钕)/硬脂酸钙/季戊四醇最佳比例为3∶1∶1;具有良好的热稳定性,静态、动态热稳定时间均达到为90和50 min以上;其加工性能和力学性能与铅盐体系相当,断裂伸长率明显高于铅盐体系。  相似文献   

5.
以山梨酸, NaOH, La(NO_3)_3, Ca(NO_3)_2, Zn(NO_3)_2为原料,制备山梨酸镧、山梨酸钙和山梨酸锌热稳定剂,并通过机械共混,制备了复合稀土热稳定剂。采用刚果红试纸法和转矩流变法考察其协同效应,从中筛选出协同效果最好的复合稀土热稳定剂。通过红外光谱法探讨了复合稀土热稳定剂的热稳定机制。研究表明:山梨酸镧-硬脂酸钙的协同效果最好,最佳复配比例为1∶1,静态热稳定时间为56.25 min,动态热稳定时间为1709 s。山梨酸镧复合稀土热稳定剂主要通过吸收中和HCl和与不稳定的氯原子络合以抑制聚氯乙烯(PVC)脱HCl,从而起到稳定作用。  相似文献   

6.
N-苯基马来酰胺酸根合镧(Ⅲ)的合成及对PVC的热稳定作用   总被引:6,自引:0,他引:6  
以马来酸酐、苯胺和氧化镧为原料合成了N-苯基马来酰胺酸根合镧(Ⅲ).对产品进行了红外光谱分析及其物性常数测定,通过刚果红法和热重法对其PVC热稳定性进行评价.结果表明,N-苯基马来酰胺酸根(OA)合镧(Ⅲ)为淡黄色粉末,熔点181℃,其化学组成符合La(OA)3·H2O,酰胺氮和羧基氧与镧离子发生了配位作用.配合物对PVC的热稳定性良好,可作为PVC的热稳定剂使用,当稳定剂加入量为PVC的2.5%时,稳定时间可达到31 min,热失重温度提高30℃;并且与硬脂酸钙之间有明显的协同作用,当配合物与硬脂酸钙按质量(1+3)形成的复合物的加入量为PVC的2.5%时,对PVc的稳定时间可以达到38 min,热失重温度提高60℃.该化合物主要通过镧与PVC中活泼的Cl反应和其有机部分的稳定作用来提高PVC的热稳定性.  相似文献   

7.
通过共沉淀法制备了锌铝镧类水滑石热稳定剂,用FT-IR、XRD和SEM扫描电镜等进行表征,用刚果红试纸法研究了锌铝镧类水滑石热稳定剂的热稳定作用及变色情况、热稳定剂和β-二酮的协同作用,与其他热稳定剂硬脂酸镧、硬脂酸钙、硬脂酸锌进行了比较。结果表明,锌铝镧类水滑石热稳定剂结晶度高、结构规整,锌铝镧类水滑石热稳定剂是具有良好的抑制PVC降解初期着色性的长期性热稳定剂,锌铝镧类水滑石热稳定剂和β-二酮助稳定剂之间存在强烈的协同作用。  相似文献   

8.
PVC/ACR共混物微观结构与性能   总被引:4,自引:1,他引:3  
本文研究了聚氯乙烯/丙烯酸酯类共聚物(PVC/ACR)共混物的应力-应变行为和冲击强度对ACR 用量的依赖关系。ACR对 PVC有良好的增韧作用,提高了PVC抗冲击性能。考察了三盐基性硫酸铅和硬脂酸钡-硬脂酸镉稳定剂对共混体系的影响,实验结果说明不同的热稳定体系对ACR改性PVC的效果有差别。动态力学性能测定结果表明PVC/ACR共混物存在两个玻璃化转变温度,证明PVC与ACR不相容性;而两个转变温度随共混物组成改变而变化,说明PVC与ACR之间存在着相互作用,PVC/ACR为部分相容体系。通过透射电子显微镜观察PVC/ACR共混物的微观结构形态表明:PVC与 ACR为两相体系,ACR呈粒状分布在PVC连续相中。但是,采用硬脂酸钡-硬脂酸镉稳定体系时,随着ACR用量增加,ACR的分散形态由粒状分散逐渐形成网络结构形态,与此相对应的共混物具有更好的抗冲击性能。  相似文献   

9.
以吡嗪-2,3-二羧酸为配体,氨水,硝酸镧为原料,制备吡嗪-2,3-二羧酸铈。经FTIR、元素分析和TG-DSC等方法表征,确定其分子结构和分子式Ce2(C6N2O4)2(NO3)2·5H2O。通过静态热稳定实验研究吡嗪-2,3-二羧酸铈的热稳定性和硬脂酸钙、硬脂酸锌等辅助类热稳定剂的热稳定性。为了提高配合物的热稳定性,将配合物与硬脂酸锌、季戊四醇进行二元复配和三元复配,并进行热稳定性分析。结果表明:当吡嗪-2,3-二羧酸铈、硬脂酸锌和季戊四醇的质量比为2:1:2时,其热稳定时间为39 min,并且抗变色性有了较大提高。吡嗪-2,3-二羧酸铈能够减缓聚氯乙烯(PVC)中HCl气体的产生,并且吸收PVC降解产生的Cl-,与稀土离子结合生成CeCl3,从而抑制PVC的降解,起到热稳定作用。  相似文献   

10.
聚氯乙烯(PVC)的热稳定性较差,在加工过程中必须通过添加2%~4%热稳定剂才能有效地阻止其热降解。工业上广泛应用铅、镉、钡、钙、锌的硬脂酸盐或油酸盐等的复合物作为PVC的复合热稳定剂,通常是二元或三元复合体系,如铅钡、镉钡、镉钡锌、钙锌体系等,由于体系内组分之间有协同热稳定性,不仅使PVC加工时期的色泽好,而且有非常好的长期稳定性。  相似文献   

11.
The thermo non-oxidative degradation of PVC and the effects of alkaline earth metal (Be, Mg, Ca, Ba) stearates were studied by thermogravimetry in the temperature range 150 to 500°C. The alkaline earth metal stearates were observed effectively reduce the dehydrochlorination of PVC. The synergistic effects of combinations of these salts with lead stearate were also studied and are discussed. Kinetic parameters such as the activation energy, order of reaction and Arrhenius factor were calculated by the Coats and Horowitz methods. The results showed that these metal stearates increase the activation energy required for the dehydrochlorination of PVC.  相似文献   

12.

Three different chemical stabilizers were introduced into neat PVC and a wood/PVC composite (containing 50 phr wood flour) to improve their thermal and structural stabilities. The changes in CIE yellowness index, polyene index, %wt loss, and decomposition temperature (Td) were monitored. The effects of type and content of thermal stabilizers, thermal ageing time, and the presence of wood flour were our main interests. The experimental results suggested that the additions of Zn and Pb stearates into PVC and wood/PVC composite could improve the thermal stability of the PVC. At the test temperature of 177°C, the additions of Zn and Pb stearates could improve the thermal stabilities of PVC by retarding the upzipped reaction and by reducing the conjugated double bonds in PVC, Pb stearate being the most suitable for thermally stabilizing the PVC. Around the Td range (~264°C), the addition of Zn stearate reduced the Td value of PVC whereas that of Pb stearate had no effect on the change in Td value. Zeolite loading could shift the Td value of the PVC from 264 to 280°C. The addition of wood particles increased the polyene content and decreased the decomposition temperature of the PVC. The effect of wood flour on the thermal and structural changes of PVC overruled that of thermal stabilizer loading.  相似文献   

13.
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.  相似文献   

14.
An i.r. spectroscopic investigation into the thermal stabilization of PVC by calcium and zinc metal soap systems has yielded new information on the role of these stabilizers. Complexation of the metal stearates occurs prior to gelation. Esterification of the polymer can also occur prior to gelation if “free” zinc stearate is present. After gelation, the stabilizing mixture acts primarily as an HCl acceptor irresective of the CaZn ratio. The chemical and physical properties imparted to the matrix by the additives determine the rate of thermal degradation during processing in the Haake rheocorder.  相似文献   

15.
熔盐电解法制备稀土合金研究进展   总被引:1,自引:0,他引:1  
熔盐电解法制备稀土合金具有成本低、成份均匀且容易控制、质量较好、易实现连续化生产等优势.本文结合稀土合金在金属结构材料、磁性材料和贮氢材料中的应用,在介绍熔盐电解的知识进展的基础上,综述了稀土分别与镁、铝、铁、钴、镍、铜等组成的合金的熔盐电解制备研究进展,并对以后的研究工作进行展望.  相似文献   

16.
Preparation of Rare Earth Trichlorides by Chemical Transport with Aluminium Trichloride The preparation of rare earth trichlorides by reaction of rare earth oxides with aluminium trichloride and their purification by means of chemical vapour phase transport with aluminium trichloride is described. By the method used especially rare earth doted rare earth trichlorides are obtainable in one step. The method furthermore allows a simple preparation of europium trichloride, which is not easy to prepare in another way. Two modifications of terbium trichloride can be prepared depending on the exact temperature conditions of the chemical vapour phase transport.  相似文献   

17.
稀土对肝脏作用的机制   总被引:15,自引:1,他引:14  
综述了稀土对肝脏作用的机制,稀土不仅能引起肝脏形态学的改变,当稀土进入肝细胞后可与多种蛋白质等分子发生相互作用,并影响多种酶的活性,还能通过信使分子干扰肝脏正常的生理功能。  相似文献   

18.
氨基膦酸螯合树脂吸附重稀土的研究   总被引:3,自引:0,他引:3  
研究了重稀土在氨基膦酸树脂的吸附行为.试验结果表明,氨基膦酸树脂对重稀土的吸附在pH=5.0的HAc-NaAc缓冲溶液时最佳;298K时静态饱和吸附容量为332mg/g干树脂;用2mol/L盐酸洗脱,洗脱率为91.2%;等温吸附服从Freundlich经验式;吸附反应中△H=10.76kJ/mol,表观速率常数k298=1.223×10-4s-1,表观活化能Ea=3.2kJ/mol.  相似文献   

19.
胡家乐  薛冬峰 《应用化学》2020,37(3):245-255
稀土元素是一个包含了由钪、钇与镧系共17种元素的系列统称,它们既具有本质上的物理化学相似性,也具有各自独特和多样的电子结构。 从化学水平上讲,稀土离子的特性决定了稀土永磁、磁致冷、超导、热释电、光学制冷、非线性光学、催化等高新技术应用的本质;从材料水平上讲,稀土功能材料是实现这些技术应用的基础。 从科技发展要求来讲,稀土功能材料的研发是实现稀土资源高质量发展的最重要途径。 本文从稀土离子特性出发,利用轨道杂化模型构建稀土离子与稀土功能材料之间的基本关系,总结了近年来不同应用领域中稀土离子在稀土功能材料的组成设计与性能优化方面的研究进展。  相似文献   

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