氯化专用聚氯乙烯树脂颗粒特性的研究——非离子型表面活性剂和链转移剂的影响

水相悬浮法生产氯化聚氯乙烯(CPVC)时,氯化速度和氯化均匀性取决于Cl2在聚氯乙烯(PVC)颗粒中的扩散程度,因而需要有能满足氯化要求的PVC专用树脂。采用以聚乙烯醇(PVA)和羟丙基甲基纤维素(HPMC)为主的复合分散剂,考察Span系列非离子表面活性剂、链转移剂等对PVC颗粒特性的影响。实验结果表明,表面活性剂的加入使PVC树脂增塑剂吸收率、平均粒径和比表面积增大,粒径分布变窄,而表观密度下降;随着链转移剂的加入,PVC树脂增塑剂吸收率、平均粒径和表观密度都增加。     

新型助分散剂在氯乙烯聚合中的应用

针对PVC生产中存在的问题，实验研制出了一种新的氯乙烯聚合用助分散剂PVALM－10HD，它是一种低聚合度、低醇解度的聚局烯醇，兼具油溶性和水溶性，不仅具有一定的外分散性而使PVC颗料变得更细、粒度更集中，且还具有内分散性而使生产的初级粒子在内均匀分散，有利于生成疏松、粒径小的初级粒子了聚集体。使用PVCLM－10HD即能保证树脂质量，又不影响生产进度，其最佳用量为0.02％－0.03％（相对于单体质量）。文中还介绍了PVALM－10HD与各种型号PVA并用时可用于低型号树脂的生产，与高醇解度PVA并用或以生产出吸油率适中、但表观密度很高的PVC树脂。     

涂覆层压法制备PVC/PVA复合薄片的性能

采用涂覆层压法制备了3层和5层结构的PVC/PVA复合薄片。探究了不同浓度、聚合度、醇解度的PVA水溶液对薄片的阻隔性能的影响,利用扫描电子显微镜(SEM)观察了不同型号、浓度的复合薄片的微观形态。结果表明:复合薄片的力学性能随着PVA溶液浓度的提高而提高;PVA溶液浓度、聚合度、醇解度的提高均能降低PVC/PVA复合薄片的透湿率;采用浓度较高或醇解度较高的PVA溶液制备的复合薄片可以更好的保持PVC/PVA复合薄片的层状结构。实验证明:用浓度为10%的PVA溶液涂覆具有PVC/PVA/PVC/PVA/PVC结构的复合薄片的阻隔性能较好。     

高浓度聚乙烯醇水凝胶性能研究

利用冷冻-解冻法制备了不同类型高浓度(30wt.%)聚乙烯醇(PVA)水凝胶,研究了PVA水凝胶的溶胀率、拉伸强度和流变特性。结果表明,高浓度PVA水凝胶的溶胀率受PVA的分子量和醇解度影响较大,PVA分子量越大,水凝胶的溶胀率越高;醇解度越高,溶胀率越低。随着冻融循环次数的增加,PVA水凝胶的强度增强;分子量越大,PVA水凝胶的强度反而越弱。在一定的频率范围内,PVA水凝胶的模量随着频率的增加而增加;随着冻融循环次数的增加,PVA水凝胶的储能模量增大。     

聚乙烯醇吹膜加工性能研究

研究了聚乙烯醇(PVA)吹膜加工性能。经两种不同的增塑剂复配增塑后，可明显改善其加工流动性，当复合增塑剂用量为25phr以上，PVA可以被较好地增塑，熔融塑化温度趋于定值。热性能研究表明，PVA为不完全结晶，其熔融曲线呈不规则分布。从PVA的流变性能可知，PVA熔体呈非牛顿性流体，剪切粘度随剪切速率增加而下降，并且醇解度较高的树脂，剪切粘度也较高。不同醇解度的PVA树脂，均能通过增塑改性后熔融挤出加工吹塑成膜。高醇解度PVA膜的水溶解温度高，而低醇解度PVA膜具有低温快速水解的性能。     

氯乙烯悬浮聚合分散剂聚乙烯醇的试验

聚氯乙烯(简称PVC)的所谓“棉絮型”树脂,因颗粒疏松,吸收增塑剂量大,容易塑化,深受加工单位欢迎。而要生产这样PVC树脂的重要途径之一是采用聚乙烯醇(简称PVA)作为悬浮聚合的分散剂,但目前我厂所用的PVA大部分是从日本进口的单一的GH—17(醇解度为88％),国内虽有少量供应,但量少,规格有限,即使     

PVA醇解度对热致变导电PVA/AgNO3_薄膜结构和性能的影响

采用不同醇解度的聚乙烯醇(PVA)和硝酸银(AgNO_3)为原料,通过溶液成膜法制备了在固相具有热致变性能的导电PVA/AgNO_3复合薄膜。采用FTIR表征了各种醇解度的PVA与Ag+之间的络合作用。通过TG、SEM、X-射线衍射、X射线能谱(EDS)等方法研究了不同醇解度的PVA/AgNO_3复合薄膜的热性能和热处理后薄膜表面形貌和结构,结果表明:不同醇解度的PVA/AgNO_3复合薄膜在160~200℃均有一明显失重峰;随着醇解度增加,SEM显示热处理后纳米银粒子尺寸减小;实验发现在温度为170~200℃时,醇解度为80%、88%、92%的PVA/AgNO_3复合薄膜其表面电阻率能从300~500 kΩ突然降低到5~20Ω(降低4~5个数量级),而醇解度为97%的PVA/AgNO_3复合薄膜表面电阻率不能发生突变,反而升高。这种具有独特电阻率-温度特性的薄膜在热敏电阻或温度传感器等方面有潜在应用。     

浅谈PVC树脂中残留VCM脱吸的影响因素及改进措施

通过PVC树脂中VCM脱吸机理和影响因素的分析 ,提出了改进措施 :(1)减少分散剂用量、加入低分子质量、低醇解度的聚乙烯醇 (LL - 0 2 ) ;(2 )在聚合配方中添加NH3·H2 O和NH4 HCO3;(3)当聚合釜压力降为 0 .15～ 0 .2 0MPa时加终止剂 (此时转化率在 85 %以下 )终止反应。采取改进措施后 ,改进了PVC树脂颗粒的皮膜结构 ,使PVC树脂中残留的VCM含量小于 5× 10 -6,达到了无毒级PVC树脂的要求。     

AEO6对铜CMP后清洗颗粒去除的影响

硅溶胶等残留颗粒是铜CMP后清洗需要去除的沾污之一.在FA/OⅡ螯合剂的协同作用下,对比了八种表面活性剂和四种添加剂对铜表面颗粒沾污去除的影响,表面活性剂包括阴离子型ALS、LABSA、MAP-K、LPS-30和非离子型AEO6、LEP-10、LDEA、APG1214,添加剂为硝酸钾、柠檬酸、乙二醇、枧油.并对表面活性剂和添加剂的浓度进行优化.清洗方式为使用PVA刷进行刷洗,清洗后通过金相显微镜检测剩余颗粒,扫描电镜观测铜表面形貌.实验得出颗粒去除效果较好的表面活性剂为AEO6,较佳的浓度为0.02 M.聚氧乙烯类表面活性剂与FA/OⅡ螯合剂的配伍效果较好.添加0.9wt％枧油可使AEO6清洗液的颗粒去除效果略微提升,枧油做复配的非离子表面活性剂.     

吸油树脂对天然橡胶性能的影响

研究了吸油树脂用量对天然橡胶(NR)的吸油率、硫化特性及物理机械性能的影响。结果表明,吸油树脂会对NR胶料产生硫化迟延作用;吸油树脂会增加NR的吸油率并随着吸油树脂和吸油时间的增加,同时能改善吸油胶料的表面质量;随着吸油树脂和吸油时间的增加,胶料物理机械性能下降。     

Influences of some polymerization conditions on particle properties of suspension poly(vinyl chloride) resin

Effects of polymerization temperature, conversions, and nonionic surfactant on the particle properties of suspension poly(vinyl chloride) (PVC) resins were investigated. It was shown that polymerization temperature has no significant influences on the mean particle size of PVC resin, and that the cold plasticiser absorption (CPA) of resin decreases linearly with the increase of polymerization temperature. Agglomeration of VCM droplets finishes before 20% conversion, and the mean particle size keeps almost constant at later stages of the polymerization process, but the CPA continues decreasing with the increase of conversion. Scanning Electron Microscopy (SEM) micrographs show that the degree of agglomeration of primary particles increases with polymerization temperature and conversion. Addition of nonionic surfactant to the VCM suspension system, as a secondary suspending agent, has a great influence on the particle properties of PVC resin. The particle size and CPA increase as the concentration of nonionic surfactant increases. The nonionic surfactant with a greater HLB value is more effective in raising the mean particle size, but is less effective in raising the CPA. It is considered that the added nonionic surfactant would be absorbed faster on the VCM/water interface than the poly(vinyl alcohol) (PVA), which was used as the primary suspending agent. Because the colloid protection ability of the nonionic surfactant is less than that of PVA, droplets become less resistant to coalescence, and the mean particle size of the final PVC resin increases consequently. The increase of porosity is caused by the combined effects of increased coalescence of VCM droplets and the nonionic surfactant's steric effect inside the droplets. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1544–1552, 2002     

Influences of individual and composed poly(vinyl alcohol) suspending agents on particle morphology of suspension poly(vinyl chloride) resin

Effects of individual and composed poly(vinyl alcohol) (PVA) suspending agents on the particle morphology of poly(vinyl chloride) (PVC) resins were investigated and discussed in the view of PVA absorption at the oil/water interface and interfacial behavior. It was shown that the percentage and surface coverage of PVA at the oil/water interface decreased with the increase of the degree of hydrolysis (DH) of PVA in the DH range of 70–98 mol %, while the interfacial tension of VC/PVA aqueous solution increased linearly with the increase of DH of PVA. PVC resin with more regular particle shape, increased agglomeration and fusion of primary particles, lower porosity and higher bulk density, was prepared by using PVA with a higher DH as a suspending agent. This was caused by the occurrence of drop coalescence at the very early stage of VC polymerization, the increase of particle shrinkage, and the lower colloidal protection to primary particles. It was also shown that the interfacial tension of VC/water in the presence of composed PVA suspending agents varied linearly with the weight composition of the composed PVA suspending agents. The particle properties of PVC resin prepared by using the composed PVC suspending agents were usually situated in between the properties of PVC resins prepared by using the corresponding individual PVA suspending agent. The particle morphology and properties of PVC resin could be controlled by the suitable choice of the composed PVA suspending agents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3848–3855, 2003     

悬浮态乳液聚合条件对聚氯乙烯树脂颗粒特性的影响

Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.     

以N-乙烯基吡咯烷酮聚合物为助分散剂制备的PVC树脂的颗粒结构和加工性能

分别在使用聚乙烯醇(PVA)分散剂、PVA/N-乙烯基吡咯烷酮(NVP)复合分散剂及PVA/[NVP/醋酸乙烯酯(VAc)]复合分散剂的条件下合成悬浮PVC树脂,比较了得到的PVC树脂的颗粒结构和加工性能。结果表明:添加NVP均聚物或不同组成的NVP/VAc共聚物作为助分散剂,均可使PVC树脂的汞总浸入体积、孔隙率和总孔比表面积增加,初级粒子聚集体之间的孔隙尺寸分布基本不变,而孔隙率增加;PVC树脂的加工塑化时间缩短,加工性能提高。     

ACR-g-VC/纳米水滑石复合材料的形态及性能

采用原位悬浮聚合制备了丙烯酸酯共聚物(ACR)接枝氯乙烯(VC)(ACR-g-VC)树脂和ACR-g-VC/纳米水滑石复合材料,并研究了复合材料的形态、加工塑化性能、力学和热性能。采用原位聚合/熔融加工得到的ACR-g-VC/纳米水滑石复合材料中,纳米水滑石基本以初级粒子形式存在,分散性明显优于由ACR-g-VC与纳米水滑石直接熔融共混制备的复合材料。水滑石含量对原位聚合/熔融加工得到的ACR-g-VC/纳米水滑石复合材料的简支梁缺口冲击强度和储能模量影响较小,而ACR-g-VC的热稳定和加工塑化性能随纳米水滑石的引入而提高。水滑石质量分数为2%的复合材料质量损失10%的温度比聚氯乙烯提高近20℃,而塑化时间缩短至22 s。     

新型氯乙烯非均相聚合动力学和成粒机理

对以正丁烷（But)为反应介质的新型氯乙烯（VC）非均相聚合动力学和成粒机理进行了研究，根据VC-But二元体系气液平衡方程，由聚合过程气相压力或组成变化计算VC聚合转化率，VC非均相聚合的诱导期不明显，自动加速现象一般发生在聚合前、中期，后期聚合速率较小，新型VC非均相聚合PVC树脂的体粒径与悬浮PVC树脂相当，数均粒径较小，PVC颗粒由基本不熔结的初级粒子组成，颗粒内部初级粒子分布密度大，粒径大，孔隙率高；而在颗粒表层初级粒子分布密度高，粒径小，孔隙率低；树脂的增塑剂吸收率远大于悬浮PVC树脂，根据PVC树脂的颗粒特性和PVC与VC／But混合液的溶解度参数差异，推断聚合成粒机理为：PVC分子链在很低转化率时就从聚合介质中沉析出来并聚集形成微区，初级粒子和颗粒；后期成粒过程包括颗粒内部初级粒子的增长和向表层的离心聚集，颗粒对新形成的大分子链及其初级聚集体的捕捉等。     

Experimental investigation of vinyl chloride drop behavior during suspension polymerization

The effects of some polymerization conditions on poly(vinyl chloride) (PVC) particles produced by the suspension polymerization process were studied on a laboratory scale. The different stages of vinyl chloride suspension polymerization were investigated experimentally by using an on-line sample withdrawal technique during reaction. It was found that the method of addition of initiator has a great effect on the PVC particle uniformity as well as the size distribution. Furthermore, when the initiator was predispersed in the continuous phase, some latex particles were formed. The effect of the type of stabilizer was also studied with two different types of PVA [partially hydrolyzed poly(vinyl acetate)]. It was found that by changing the stabilizer, the particle size, the porosity, and the morphology could change. When H80 (PVA with a degree of hydrolysis of 80% and a molecular weight of 259,000) stabilizer was used, the rigidity of the PVC particles was weak. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 127–134, 1997     

Absorption of trioctyl trimellitate into mass‐polymerization and suspension‐polymerization poly(vinyl chloride)

Poly(vinyl chloride) (PVC) slush powder has been widely used; we prepared it by dry blending. We found that the absorption of plasticizer by the PVC resins was the most important factor in the dry‐blending process and, further, that different types of PVC resin had different absorption rates. This results of this study provide new information about the relationship of absorption to PVC and other parameters. Haake rheomix testing and the quantity of plasticizers absorbed by the PVC resins were used to characterize the absorption process. Suspension‐polymerization poly(vinyl chloride) (SPVC) and mass‐polymerization poly(vinyl chloride) (MPVC) in different sizes were used for the test. The results showed that the MPVC absorbed the plasticizer more quickly than SPVC, especially at a higher temperature. However, for the same PVC resin type, the absorbing speeds were nearly independent of particle size. The studies that used a scanning electric microscope and specific surface area revealed that the morphology of the two types of particles was different. The surfaces of the individual particles of SPVC were smoother than those of MPVC. There was a “skin” covering the SPVC particles, whereas with the MPVC particles, the primary polymer was exposed directly on the surface. This difference in morphology was shown to be a significant factor in the different rates of absorption of the plasticizers for the different PVC resins. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2369–2374, 2004     

Effect of the phase ratio on the particle properties of poly(vinyl chloride) resins produced by suspension polymerization

The effects of the dispersed phase to continuous phase ratio (weight of VCM (gr)/weight of water (gr) (φ = g_VCM/g_water)) on the particle properties of a poly(vinyl chloride) (PVC) suspension were investigated experimentally. A series of experiments were performed with different φ values in a pilot‐scale reactor. The cold plasticizer absorption of the resin decreased with φ. Scanning electron micrographs showed that by the reduction of φ, many of the produced particles had a regular shape, a smooth surface, and greater porosity. An increase in φ caused a wider and multimodal particle size distribution of the produced PVC particles. The mean particle size and bulk density also increased with φ, whereas the molecular weight and polydispersity index did not change. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008