热稳定剂对PVC紫外光老化过程中微观结构及宏观性能演变的影响

通过UV-Vis、FTIR、DSC、以及色差、力学性能的测试表征,实时追踪分析了在紫外光老化过程中,含Pb、Sn以及Ca-Zn热稳定剂的PVC体系微观结构和宏观性能的演变过程.结果表明,在相同光老化条件下,PVC/Pb、PVC/Sn和PVC/Ca-Zn体系的微观结构变化规律基本一致,过程中主要的化学反应是,大分子吸收光能后,发生脱HCl生成共轭双键的反应、生成羰基的氧化反应、交联反应和降解反应;不同热稳定剂的作用,主要表现在对于微观结构变化的幅度和动力学过程的影响不同.相应地,3种体系的外观色差和力学性能的变化规律也相似,但色差的变化程度和速度以及老化后力学性能的保持率因所含热稳定剂的不同而不同,其中含Sn体系的颜色稳定性最好,含Pb体系的力学性能保持率最高。     

关于ABS树脂热失重数据的计算

在解析TG曲线时,常用的方法有积分法和微分法,但反应级数需要通过预先假定和尝试确定.本文以ABS树脂热解反应为对象,采用三次样条插值函数求得热解反应速率,利用二元线性回归经一次计算,同时求得ABS树脂热解反应表观活化能E,视频因子A以及反应级数n,并把所得结果与积分法和微分法作了比较,确定了各自方法所适用的转化率区间.本文还考察了不同升温速率对热解动力学参数的影响.     

(NBR/PVC)/CuSO_4复合材料中配位交联反应的研究

采用差示扫描量热法(DSC)和傅立叶转换红外光谱(FT-IR)对丁腈橡胶/聚氯乙烯合金/无水硫酸铜((NBR/PVC)/CuSO4)混合物的配位交联反应进行了研究.结果表明,(NBR/PVC)/CuSO4共混物在升温过程中出现两个放热峰,分别归因于腈基(—CN)和CuSO4之间的配位交联反应和体系中NBR/PVC的自交联反应.通过对共混物配位交联反应动力学参数的计算发现,混合物中CuSO4含量的多少并未对体系配位交联反应的进行产生影响.同时共混物中PVC的存在促进了配位交联反应的进行,降低了铜离子(Cu2+)与—CN之间配位交联反应的表观活化能Ea.     

PVC硬脂酸轻稀土热稳定剂的复配与应用研究

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。     

一种煤与两种城市污水污泥混合热解的热重分析

采用热重分析法对一种煤和两种城市污水污泥（S1和S2）及其混合物进行了热解实验研究,揭示了煤和污泥在氮气中的热解特性及污泥对煤热解特性的影响。煤和污泥的热解特性参数不同,主要表现在总失重率、失重速率及挥发分析出温度区间等。煤与污泥S1混合有助于增加样品的热解总失重率,提高失重速率;污泥S1与煤的挥发分析出区间部分重合,污泥灰中含的无机物对煤的热解起到催化效果;煤和S2污泥混合后热解反应过程中无明显相互作用;煤与城市污水污泥混合物的相互作用与样品特性和混合比例有关。     

聚氯乙烯复合热稳定剂中铅镉钡的同时测定

聚氯乙烯（PVC）材料广泛应用于建筑、电讯、交通、电子、化工、包装等行业。然而，PVC加工时存在着一个致命的弱点，就是其流动温度为136℃，分解温度为140℃，两者相差仅4℃，给加工带来很大难度，为了能顺利加工就必须加入热稳定剂，热稳定剂是PVC加工不可缺少的主要助剂之一。热稳定剂种类繁多，我国目前大量使用的稳定剂为铅盐及金属皂等稳定剂，产量高达4．5万吨。由于铅、镉、钡等金属元素具有一定的毒性，使用中易造成环境污染，有害于人体健康，因此必须严格加以控制。     

原位担载Fe2S3催化剂煤的热解动力学研究

用加压热天平研究了原位担载纳米级Fe2S3催化剂的大柳塔次烟煤的加氢热解动力学,考查了2.0MPa氢气氛或氮气氛下原煤及担载催化剂的煤热解失重过程,计算了活化能E和指前因子A等热解动力学参数。结果表明,煤原位担载Fe2S3催化剂后热失重速率比原煤有较大程度的增加,最大热解速率的特征温度也比原煤降低。特别是煤在表面性剂十六烷基三甲基溴化铵溶液中担载Fe2S3催化剂后的热解反应速率高于水溶液中担载同样催化剂的热解反应速度。原位担载Fe2S3的煤及原煤的热解反应过程符合一级反应动力学。     

城市生活垃圾典型有机组分混合热解特性的研究

利用自行设计的较大物量(约10 g)的热重分析装置对城市生活垃圾典型有机组分（纸屑、木屑、织物、塑料、橡胶、厨余）的混合热解特性进行了实验研究，并用最小二乘法计算得到由若干平行反应组成的热解反应动力学模型，实验结果与模型计算结果吻合较好。在此基础上对城市生活垃圾典型有机组分混合热解中的交互影响和非线性规律进行了分析。结果表明，城市生活垃圾典型有机组分混合热解动力学模型由2个～4个平行反应组成；混合热解中有反应发生合并的现象；热效应和组分比例对混合物综合热解特性有显著影响。     

PVC热稳定剂——羧酸疏基乙酯锑的合成及性质

以Sb2O3和HSCH2CH2OH为原料合成Sb(SCH2CH2OH)3;再将Sb(SCH2CH2OH)3与RCOOH反应,以钛酸丁酯作催化剂,二甲苯为溶剂,加热回流反应,得到酯锑。产品的热稳定性能测试表明：当逆酯锑的添 加量为2％时,PVC树脂的热稳定时间为8－40min(200℃）。还对该类热稳定剂对PVC的热稳定机理进行了初步探讨。     

生物质秸秆热重分析及几种动力学模型结果比较

利用热重分析在不同升温速率和氮气气氛下对两种生物质（玉米秸秆和稻秆）的热失重行为进行了研究。根据热重实验数据，采用四种利用热分析获取动力学参数的方法（Coats-Redfern法，Doyle法，最大速率法和分布活化能模型(DAEM)），计算生物质秸秆热分解反应活化能E、反应级数n及频率因子A，并进行比较。结果表明，采用不同的处理方法，得出的热分解动力学参数不同。利用Coats-Redfern法，玉米秸秆和稻秆在热解主要阶段（失重约5 w%～80 w%时）可由一段一级反应过程描述，升温速率10 K/min时活化能值分别为68.8 kJ/mol和70.0 kJ/mol。Doyle法和DAEM模型得到的结果较为接近，可以得到生物质热解过程中的活化能随失重率的变化曲线。生物质秸秆热解包含分子键能断裂的一系列复杂、连续反应过程。     

Studies on Thermal Stability and Fluid Property of PVC Filled with Hydrotalcite

IntroductionIt is well known that PVC is a kind of valuableplastic and used in many fields.But PVC isunstable against heat and light,and at the heat-molding step,the thermal decomposition of it maytake place.Finally,the decomposition will reducethe mechanical strength and lose otherproperties ofPVC.In order to overcome those disadvantages,athermal stabilizer is added in the PVC material toreduce the thermal decomposition,and organiccompounds of metals such as Sn,Pb,Ca,Ba,Znand Cd are u…     

Investigations on poly(vinyl chloride). III. Effects of metal oxides upon thermal decomposition of poly(vinyl chloride)

Thermal decomposition mechanisms of poly(vinyl chloride) (PVC) and the effects of a few metal oxides on the pyrolysis of PVC were previously reported. In the present work, 33 metal oxides were investigated to determine their effects on the thermal decomposition of PVC, by using a pyrolysis gas chromatograph. Most acidic oxides accelerate the recombination of chlorine atoms with double bonds, since PVC containing these metal oxides easily release lower aliphatics, toluene, ethylbenzene, o-xylene, and chlorobenzenes. On the other hand, most basic metal oxides, such as oxides of alkaline earths or silver, inhibit the recombination. These tendencies observed in the thermal decomposition of PVC agree with the contributions of corresponding metal salts to the dehydrochlorination of PVC proposed by other workers. This means that thermal decomposition or dehydrochlorination of PVC is affected by irregularities in head-to-tail linkages formed by the recombination of chlorine atoms during heat treatment of PVC.     

Thermal and burning properties of wood flour-poly(vinyl chloride) composite

The present study deals with the effects of wood flour on thermal and burning properties of wood flour-poly(vinyl chloride) composites (WF-PVC) using thermogravimetric (TG), cone calorimetry (CONE), and pyrolysis?Cgas chromatography/mass spectrometry (Py?CGC/MS). TG tests show that an interaction occurred between wood flour and PVC during the thermal degradation of WF-PVC. Wood flour decreased the temperature of onset of decomposition of PVC. However, the char formation could be increased by adding wood flour to PVC. CONE test indicates that wood flour had positive effects on heat release and smoke emission of PVC. Comparing with PVC, WF-PVC reduced average heat release rate and the peak HRR by about 14 and 28%, respectively; smoke production rate was also decreased. The degradation mechanism was studied by Py?CGC/MS. The results show that the volatile pyrolysis products of WF-PVC are very different from PVC. The yields of HCl and aromatic compounds decreased dramatically, and the aliphatic compounds increased by the incorporation of WF.     

Study of the effect of stabilizer on the degradation of poly(vinyl chloride) by pyrolysis–gas chromatography

The effect of stabilizer on the thermal degradation of poly(vinyl chloride) was studied by means of pyrolysis–gas chromatography. The stabilizers used in this study were dibutyltin dilaurate, dibutyltin bis(n-dodecyl mercaptide), barium stearate, and zinc stearate. PVC containing these stabilizers was degraded in a stream of nitrogen at temperatures ranging from 350 to 570°C. It was found that observed drastic reduction of benzene yield from the PVC containing zinc stearate had a close correlation with the formation of crosslinking structures.     

基于热重红外联用分析的PE、PS、PVC热解机理研究

利用TGA-FTIR联用技术考察了PE、PS、PVC三种典型塑料的热解特性。结果表明,热稳定性从弱到强依次为PVC、PS、PE。PE热解反应过程为典型的一段式反应,红外光谱分析结果表明,PE热解过程为无规则断链形式,生成产物成分复杂,且随热解过程而改变,开始以饱和烃基团为主,中后期以烯烃基团为主,同时有少量炔烃;PS热解过程同样为一段式反应,红外光谱显示主要热解产物为苯乙烯单体,说明热解过程主要是苯乙烯的解聚过程;PVC热解过程较为复杂,主要分为脱氯阶段和共轭多烯重构阶段,红外光谱结果表明,产物中有芳香族化合物。脱氯过程和共轭多烯重构、环化过程在时间和空间上有重合,给二噁英类污染物的生成制造了可能。     

Vanillin–Schiff’s bases as organic thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride)

Vanillin–Schiff’s bases (VSB) were examined as thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride) (PVC) in air at 180 °C. Their high stabilizing efficiency were shown by their high thermal stability value (Ts), which is the time elapsed for the detection of HCl gas, if compared with dibasic lead carbonate and cadmium–zinc soap reference stabilizers used industrially, with better extent of discoloration. Blending these derivatives with reference stabilizers in different ratios greatly lengthens the thermal stability and the extent of discoloration of the PVC.Condensation products of Vanillin with amines are very active biologically, besides having good complexation ability with metal ions. The Ni²⁺ and Co²⁺ complexes of VSB derivatives gave better thermal stability and less discoloration than the parent organic stabilizer. Also, blending these complexes with either of the used reference stabilizers in different ratios gave better thermal stability and lower extent of discoloration. Thermogravimetric analysis confirmed the improved stability of PVC in the presence of the VSB derivatives, compared to blank PVC, PVC stabilized with reference stabilizers and PVC stabilized with binary mixture of VSB derivatives with reference stabilizer.The stabilizing efficiency of Vanillin–Schiff’s base (VSB) derivatives is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the organic stabilizer.     

Novel antimicrobial organic thermal stabilizer and co-stabilizer for rigid PVC

Biologically active N-benzoyl-4-(N-maleimido)-phenylhydrazide (BMPH) was synthesized and its structure was confirmed by elemental analysis and various spectral tools. It was examined as a thermal stabilizer and co-stabilizer for rigid poly (vinyl chloride) at 180 °C in air. Blending BMPH with reference samples in different ratios greatly lengthens the thermal stability value and improves the extent of discoloration of PVC. TGA confirmed the improved stability of PVC in presence of the investigated organic stabilizer. GPC measurements were done to investigate the changes occurred in the molecular masses of the degraded samples of blank PVC and PVC in presence of the novel stabilizer. BMPH showed good antimicrobial activity towards two kinds of bacteria and two kinds of fungi.     

Effect of stabilizers in the thermal treatment of PVC—XVI: Study of the stabilization efficiency of antimony tris(isooctyl thioglycolate) in PVC

Antimony tris(isooctyl thioglycolate) [Sb(IOTG)₃] is a powerful thermal stabilizer for PVC, particularly if added in quantities up to 2% (m/m) with respect to PVC. During the stabilizing action, (IOTG)₂SbCl is formed while the rate of elimination of HCl from the polymer decreases appreciably. The thermal degradation is accelerated as (IOTG)SbCl₂ appears. During long-term heat treatment of PVC mixtures stabilized with Sb(IOTG)₃, the organoantimony compound decomposes and its activity decreases.     

The effects of thermal processing on PVC—X. The interaction between bound antioxidants and tin stabilizers

It is shown that a thiol u.v. stabilizer and a thiol heat stabilizer can be effectively bound to PVC during processing in the presence of an alkyltin stabilizer. Thiol u.v. stabilizer interferes with the processing stability of PVC to a lesser extent than does a conventional u.v. stabilizer (2-hydroxy-4-octoxybenzophenone).     

Organic thermal stabilizers for rigid poly(vinyl chloride). Part XIII: Eugenol (4-allyl-2-methoxy-phenol)

Eugenol (4-allyl-2-methoxy-phenol) has been examined as a thermal stabilizer and co-stabilizer for rigid PVC in air, at 180 °C. Its high stabilizing efficiency is detected by its high thermal stability value (Ts) when compared with some of the common reference stabilizers used industrially such as dibasic lead carbonate, calcium-zinc soap and octyl tin mercaptide.Blending this organic stabilizer with some of the reference stabilizers in different ratios had synergistic effect on both the induction period and the dehydrochlorination rate together with the longer extent of discolouration of PVC stabilized by eugenol as compared with the blank and the samples stabilized with reference commercial stabilizers.A probable mechanism for the stabilizing action of eugenol has been proposed. The stabilizing efficiency is attributed partially to the stabilizer's ability to intervene in the radical chain degradation process of PVC and to the replacement of the labile chlorine atoms on PVC chains by a relatively more stable moiety of the organic stabilizer.