热稳定性好氯化聚氯乙烯制造

氯化聚氯乙烯（CPVC）通常要在较高温度下进行加工，故要求其具有较高热稳定性。日本积水化学公司以氯乙烯100、水120、PVA0．04、HPMC0．01、月桂酸0．5和EHP引发剂0．08份配方料进行悬浮聚合制得的PVC进行氯化制成含氧量66．5％的CPVC。此种产品具有较高的热稳定性和抗冲击强度。热稳定性好氯化聚氯乙烯制造     

纳米微晶纤维素热稳定性的研究进展

纳米微晶纤维素来自天然高分子聚合物,具有成本低、强度高、轻便等特点,并可循环利用或者生物降解。纳米微晶纤维素研究倍受关注,但纳米微晶纤维素存在一些实用方面的困难。制备过程复杂、热稳定性差等是限制纳米微晶纤维素大规模商业化应用的主要的因素。本文综述了纳米微晶纤维素的热降解机理及其热稳定性影响因素,探讨了提高其热稳定性的途径。     

聚乙二醇定形相变材料的热稳定性

利用热重分析仪对不同分子量、不同支撑材料、不同配方的聚乙二醇(PEG)定形相变材料的热稳定性进行了分析。结果表明,机械加工方法有可能会对PEG分子链有破坏作用,PEG定形相变材料具有良好的热稳定性。随着PEG分子量的增加,PEG定形相变材料的热分解温度越来越高,热稳定性更好。活性炭颗粒(ACG)和膨胀石墨(EG)都会使PEG相变材料的热分解温度降低,热稳定性有所降低。随着PEG定形相变材料中支撑材料含量的增加,定形相变材料的热稳定性降低。     

阻燃ABS的热稳定性研究

建立了评价阻燃丙烯腈–丁二烯–苯乙烯塑料(ABS)材料热稳定性的不同方法,从阻燃剂及添加剂的分解机理进行分析,发现Mg O对四溴双酚A具有很好的热稳定作用,硬脂酸镁/有机锡热稳定剂组合很好地抑制氯化聚乙烯(PE-C)的热降解,开发了一种具有较好热稳定性的阻燃ABS热稳定体系,具有很好的市场应用前景。     

UPVC用有机锡系稳定剂的热稳定性测试方法研究

研究了硬质聚氯乙烯(UPVC)压延用有机锡稳定剂的热稳定性能的评价方法,包括静态烘箱法、动态双辊塑炼法等,考察了有机锡稳定剂对PVC静态、动态及残留热稳定性的影响,结果表明:辛基锡稳定剂具有较好的初期热稳定性,但长期热稳定性大小依次为丁基锡稳定剂甲基锡稳定剂辛基锡稳定剂。     

不溶性硫黄热稳定性测试分析

分别采用油浴法和差式扫描量热法测定不溶性硫黄的热稳定性,并探讨提高不溶性硫黄热稳定性的途径.结果表明,恒温差式扫描量热法能够较准确、全面地评价不溶性硫黄的热稳定性;不溶性硫黄采用高温气相法合成、提高相对分子质量均有利于提高其热稳定性.     

炭黑对高温硫化硅橡胶热稳定性的影响

研究了耐热助剂炭黑对高温硫化硅橡胶热稳定性的影响。结果表明,添加少量炭黑可获得好于氧化铁、氧化铈的热稳定性;炭黑用量过多时,会使硫化胶热稳定性下降;炭黑的热稳定效果与其粒径有关,细粒子炭黑热稳定效果较好;氧化铁红与炭黑具有协同作用。     

PP基木塑复合材料热稳定性研究进展

分析了聚丙烯(PP)基木塑复合材料中各组分的热稳定性,综述了PP基木塑复合材料热稳定性的研究进展,主要是植物纤维、偶联剂、抗氧剂、阻燃剂、弹性体等对复合材料热稳定性的影响。     

浅谈日用陶瓷热稳定性工艺控制

热稳定性是日用陶瓷产品的重要性能指标之一,本文通过对陶瓷微观结构、坯釉匹配、器型等方面的分析,探讨了影响热稳定性的机理,并在此基础上梳理了与热稳定性相关的工艺流程,包括原料的选择、配方优化、颗粒级配、成形细节、施釉控制和烧成工艺制度等方面,为日用陶瓷产品热稳定性的提升提供基础。     

有机颜料热稳定性的研究(Ⅰ)——颜料分子的极性与热稳定性

一、前言有机颜料的热稳定性对其应用性能具有十分重要的实际意义。为改进和提高其热稳定性能,在合成新型化学结构颜料的同时,还深入地研究了有机颜料的化学结构、晶型、后处理方法等对其应用性能的影响;研究颜料的分子结构、取代基的特性与颜料的热稳定性、热分解历程之间的关系。尽管某些无机颜料具有突出的耐热性能和耐溶剂特性,但往往毒性较大;而有机颜料则具有鲜艳的色光,高的透明度及着色力,除各     

Statistical thermal stability of PVC

Experimental design was used to optimize the processing parameters for the decomposition of poly(vinyl chloride). Factorial design and face centered composite design (FCC) were applied to determine the optimum conditions. A total of 10 g PVC powder was mixed with different amounts of zinc stearate (ZnSt₂) and natural zeolite and tested for thermal stability. Factorial fitted model was explained by first order pattern due to the significant main effect regression constants, and FCC model was described by second order model owing to higher order polynomial coefficients. FCC design was superior to factorial design as FCC considers not only its pure quadratic effects contribution but also its higher overall desirability for thermal stability of PVC. For factorial design the optimum conditions were determined as 163.06 mg for ZnSt₂, 399.99 mg for zeolite, and 140°C for temperature with desirability of 0.933. However, 400 mg for ZnSt₂, 333.24 mg for zeolite, and 140°C for temperature with desirability of 0.956 were obtained as the optimum conditions by FCC design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚氯乙烯树脂热稳定性探讨

通过对聚氯乙烯降解机理的分析,提出在聚合体系中添加助剂并控制单体质量,改进工艺措施,提高PVC树脂制品的热稳定性。     

Nature of the thermal stability of polyheteroarylenes

Conclusions The dependence between structure and thermal stability of polyheteroarylenes has been examined.It has been shown that the thermal stability of polymers depends on two basic factors — an energy factor, determined by the breaking energy of skeletal bonds in the polymer chain, and an entropy factor, which characterizes the probability of effecting the elementary acts of chemical reactions and is expressed via the mobility of the macromolecules.Symmetry of the monomeric units in a chain, regularity in the macromolecules, the absence of bulky substituents, and a high degree of crystallinity aid in reducing the molecular mobility of heterocycloaromatic polymers and in increasing their thermal stability.Analysis of the factors which aid in thermal stability has made it possible to arrive at the conclusion that the polymer glass transition point or melting point can serve as a criterion of the thermal stability of polyheteroarylenes.Published in discussion order.Translated from Khimicheskie Volokna, No. 4, pp. 22–26, July–August, 1987.     

Styrene-N-Vinylcarbazol copolymers with enhanced thermal stability

Styrene copolymers with low (up to 5 wt.-%) N-vinylcarbazol content were prepared. The copolymers showed enhanced thermal stability in comparison with the pure polystyrene. This is explained by a charge transfer complex formation between the carbazol rings as donor and the radicals, formed during the degradation, as acceptors.     

硅钛弹性体的合成及热稳定性研究

以三甲基三苯基环三硅氧烷为原料,四氯化钛为钛源,一步法合成了不同硅钛比例的硅钛弹性体。采用FT-IR(红外光谱)法、FT-Raman(拉曼光谱)法、NMR(核磁共振波谱)、GPC(凝胶渗透色谱)法对产物进行结构表征,利用DSC(差示扫描量热)法研究了产物的玻璃化转变温度,利用TGA(热重分析)研究了产物的热性能。研究结果表明:随着硅钛比例的升高,产物的玻璃化转变温度降低,但高温固化会使硅钛弹性体的玻璃化转变温度变高;硅钛弹性体TSE20的综合热性能较好,它的初始分解温度为322℃,800℃时的残炭率为50.6%。     

Synthesis and thermal stability of carborane-containing phosphazenes

Carborane-substituted polyphosphazenes were prepared by the thermal polymerization of phenyl-carboranyl pentachlorocyclotriphosphazene. Successive isothermal vacuum pyrolyses were conducted on the polymer and examined for structural changes by infrared spectroscopy. The degradation products were ascertained by gas chromatography-mass spectrometric analysis. It was found that the presence of the carborane group improves the thermal stability of the polymer by retarding the ring-chain equilibrium processes of decomposition.     

On the thermal stability of xanthan gum

The thermal stability of xanthan gum in dilute aqueous solutions at 90°C is considered. The relative viscosity as a function of ageing time is discussed, and it has been found to depend on the polymer concentration and conformation as well as on the salt content. The effectiveness of a quencher demonstrates the existence of a free-radical process in the degradation. During ageing, the molecular weight first decreases by rapid random hydrolysis of the main chain and loss of the pyruvate and acetate substituents. Later, oligomers are formed corresponding to a breakdown of both the side chain and the main chain. The identification of cellodextrins in the oligomer pool demonstrates the second effect.     

型煤热稳定性影响因素探讨

简要介绍通过正交实验,探讨了矸石颗粒、粘合剂、膨润土对型煤热稳定性的影响;通过对比实验得出矸石颗粒对型煤热稳定性影响比矸石粉影响大。     

Designability and thermal stability of protein structures

Only about 1000 qualitatively different protein folds are believed to exist in nature. Here, we review theoretical studies which suggest that some folds are intrinsically more designable than others, i.e. are lowest energy states of an unusually large number of sequences. The sequences associated with these folds are also found to be unusually thermally stable. The connection between highly designable structures and highly stable sequences is generally known as the ‘designability principle’. The designability principle may help explain the small number of natural folds, and may also guide the design of new folds.     

PVC热稳定性的影响因素分析及解决措施

分析了电石法PVC树脂生产过程中产品热稳定性的影响因素,主要包括原料质量控制指标、工艺条件及聚合生产过程中各种助剂的选用。提出了在生产中需要采取的措施。