PVC异型材塑化质量的探讨

就PVC树脂在塑化过程中的转化、工艺温控曲线、配方设计和挤出机性能分别与PVC异型材的塑化质量等方面对PVC型材塑化质量进行了讨论，阐述了保证PVC异型材的塑化质量的措施和方法。试验证明，要保证PVC异型材达到良好的塑化质量，必须同时做好三方面：挤出工艺温控遵循马鞍山曲线，选择质量好的助剂与确定适宜的用量，提高生产设备的装配精度。     

硬质PVC管材塑化度及调整

在加工过程中，硬质PVC的粒子结构将发生很大变化，在较低加工温度下，由于热和剪切力的作用，颗粒分解成初级粒子，随着温度的升高，初级粒子部分被粉碎；当加工温度更高时，初级粒子可全部粉碎，晶体熔化，边界消失，形成二维网络，这一过程称为熔融或凝胶化，一般称为塑化。塑化度正是制品结晶程度与PVC初级粒子熔化程度的反映，塑化度可用流变法测量。PVC塑化后在制品中形成了贯穿的结晶网络，这种结构的变化，必然引起力学性能的改变，进而影响制品的性能。     

机械力和化学双重降解制备PVC加工助剂的研究

采用机械力和化学双重降解结合的方法,研制了一种低相对分子质量PVC(LMPVC)。讨论了影响LMPVC 性能的工艺因素和LMPVC对PVC加工性能的作用。结果表明,LMPVC与普通的PVC化学结构相同,因此与其有良好的相容性。其塑化温度较低而熔体流动性较高,对普通的PVC有良好的塑化作用,并且不影响其力学性能。当采用相对分子质量为3．58×104的LMPVC作为加工助剂时,PVC的起始塑化温度降至165℃,185℃时的塑化时间降至141 s。     

PVC挤塑制品的着色

通过对PVC挤塑材料性能的分析，探讨了影响PVC挤塑制品着色的主要因素；从原材料及加工过程的特点，寻找控制着色产品色泽的主要因素；认为对材料的配方及配混工艺、挤塑加工工艺进行严格控制，是控制好PVC挤塑制品色泽的主要途径。     

新旧两条涂刮法PVC运输带生产线设备及配混工艺的对比

对比介绍了两套涂刮法PVC运输带生产线的塑化成型设备、真空浸糊设备、匀糊及刮糊设备、冷却循环设备、加热及其循环系统的设备构造和工作原理。在配混方面设备及工艺的差异与改进中着重介绍了液料分储部分、辅料分储部分、主料分储部分、总料热混部分所用设备的工作原理以及配混工艺方面的先进之处。无论在生产效率还是产品质量上,具有高度自动化程度的新生产线都比以前的老生产线有着无可比拟的优势。     

PVC异型材塑化质量探讨

从PVC树脂在塑化过程中的转化、工艺温控曲线配方设计、挤出机性能等四个方面对PVC异型材塑化质量进行了讨论，阐述了保证PVC异型材的塑化质量的措施和方法。     

PVC物料挤出塑化的浅议

本文围绕PVC物料挤出塑化质量中的内在质量，从挤出机结构与发展、PVC物料在挤出机中挤出塑化的历程与机理、配方与工艺等三方面对PVC物料挤出塑化进行了较详细的讨论，阐述了提高塑化质量的相应措施。     

二氧化硫凝聚MBS胶乳研究

提出了用二氧化硫凝聚MBS胶乳的新方法,研究了各种因素对凝聚时间、颗粒粒径分布和粉体堆积密度的影响,确定了最佳工艺条件:MBS胶乳的质量浓度为80～120g/L,凝聚温度50～60℃,搅拌速度200r/min,二氧化硫体积流量25 L/min.经8 m3凝聚釜生产试验,所得样品有较好的形貌,颗粒多为圆球;堆密度0.42;粒度分布集中,40和180目之间的颗粒含量达96%.PVC/MBS合金性能测试结果表明,由于塑化时间缩短,抗冲强度和透光率也得到了改善.     

PVC异型材塑化质量的探讨

从PVC树脂在塑化过程中的转化、工艺温控曲线与PVC异型材的塑化质量、配方设计与PVC异型材的塑化质量、挤出机性能与PVC异型材的塑化质量等四方面对PVC异型材塑化质量进行了讨论,阐述了保证PVC异型材塑化质量的措施和方法。     

悬浮法PVC树脂塑化的影响因素

简要分析了PVC树脂聚合度、树脂颗粒特性、加工设备、加工配方及助剂对悬浮法PVC树脂塑化的影响。     

注塑用聚氯乙烯干混粉料流变性能的研究

用国产注塑机直接采用聚氯乙烯(PVC)干混粉料注塑硬质聚氯乙烯(RPVC)管件是一个新课题。本文着重介绍在美国哈克(HAAKE)EU-5型转矩流变仪上筛选配方,对PVC干混粉料在加强稳定化、阻止热分解、改善加工性能和实现内外润滑的平衡等方面,进行初步探讨;同时结合生产实践,阐述了干混粉料的制备,机筒模具温度、塑化注塑压力等工艺全过程的控制条件,以及注塑管件在出现缺陷时的解决办法。     

Untersuchungen zur struktur von emulsions-polyvinylchlorid

The structural characteristics of PVC prepared by bulk or suspension polymerization as well as their relationships to synthesis and processing conditions have repeatedly been investigated. Thus, grains aggregates, particles, domains and microdomains have to be discerned according to Geil. In our electron microscope studies emulsion PVC powder obtained by spray drying of aqueous PVC latices and used in preparing pastes were investigated. The grain structure was found to change in preparing pastes and subsequent gelation. With increasing temperature of gelation the grains disintegrate, particles arrange in dense packings and, finally, loose their individuality. Due to diffusion of the plastiziser the particles acquire distinctly discernible microdomain structures. Microdomains are found to be the dominating structural characteristic of PVC gelation products.     

Sintering of PVC

Although PVC is counted as one of the amorphous plastics it possesses a distinct powder grain structure. This structure is responsible for various effects; for example it is impossible to sinter thick pieces of rigid PVC dryblend possessing satisfactory mechanical properties. For this application, it is necessary to break down this powder structure into smaller parts, called primary particles, by mechanical shearing and covering these particles with processing auxiliaries enabling it to be sintered. PVC can then be melted by the influence of temperature and pressure in the same way as other thermoplastic materials. For this reason, tests were carried out to determine the best material configuration and the necessary data for the compounding and shearing process, and the sinter conditions. A continuously working roll mill was used to break down the structure. The rolls of this equipment are provided with grooves inclined at a certain angle. With this construction it is possible to achieve a high shearing rate at a low mass-temperature. Furthermore, all additives can be added during the rolling process, so that no additional mixing process is necessary. These gelable pellets, made by the roll mill, can thus be formed in a die into plates of different thicknesses. Samples were pressed by varying compounding and sintering conditions and these were tested for mechanical properties.     

Dynamic mechanical properties and morphology of styrene-divinylbenzene copolymer/poly(vinyl chloride) systems. (II). Effect of polymerization temperature

Effect of polymerization temperature on the phase-separated structure of the composite materials [P(St-DVB)/PVC systems] prepared by copolymerization of styrene (St) and divinylbenzene (DVB) in the presence of fine poly(vinyl chloride) (PVC) powder was studied by electron microscopy and dynamic mechanical test. P(St-DVB)/PVC systems have the two-phase nature with a styrene-divinylbenzene copolymer as the continuous phase [P(St-DVB) phase) and a PSt/PVC composite as the dispersed phase (PSt-PVC phase), in which PSt penetrates into the PVC domain. The crosslinking density of the P(St-DVB) phase is larger than that estimated from the recipe in the feed, suggesting that there exists a difference of the diffusion constants of styrene and divinylbenzene into the PVC particles on the paste formation and the polymerization process. The changes of the phase-separated structure of P(St-DVB)/PVC systems polymerized at various temperatures are also explained on the basis of the difference between the diffusion behavior of styrene and that of divinylbenzene into fine PVC particles at these temperatures.     

Effects of dry blending on morphogy of PVC powder particles

Mass and suspension PVC were blended on a Fielder mixer and changes in powder morphology and additive distribution investigated. The techniques used to characterize and assess processing behavior have included microscopy, density, size analysis, torque, and capillary rheometry. The particulate structure of PVC remained intact, and there were no pronounced differences in the processability of blends discharged at different temperatures. In the absence of shear PVC particles are largely unchanged in character. Solid additives do not appear to enter into resin particles while liquid stabilizer readily does so.     

Processing of precipitated nongranular PVC in the brabender measuring mixer

The structure and properties of processed poly(vinyl chloride) (PVC) depend on temperature, shear rate, operations time, and morphology of the PVC grains. The aim of our research was the preparation of a nongranular PVC and the examination of its processing during kneading in a Brabender plastographometer in comparison with the processing of commercial PVC. It was stated that grains of virgin PVC‐S61, a commercial suspension resin, cause a self‐heating of the compound during kneading in such a way that point X of the plastograms occurs at a temperature 15°C lower than that of precipitated PVC (i.e., PVC without grains). As a result of self‐heating, time of compound processing needed to reach point depends largely on the grain morphology of the PVC. The less compact structure, the smaller bulk density, and the greater absorption of plasticizer, result in a longer processing time. Homogeneous, loosely packed particles of powder and the crystalline structure of precipitated PVC are different from PVC‐S61 morphology and cause a high degree of gelation and low melt flow rate values for compounds processed at 175°C and higher. J. VINYL ADDIT. TECHNOL., 18:147–152, 2012. © 2012 Society of Plastics Engineers     

释放负离子的PVC糊树脂/天然矿物复合材料研究

将具有李泽冈环的天然矿物六环石进行表面处理后,与PVC糊树脂及助剂混合制备了PVC糊树脂/天然矿物复合材料。通过热失重曲线考察了六环石的热稳定性,用SEM观察了六环石在PVC糊树脂中的分散状况,用空气离子测试器测试了复合材料的负离子释放能力。结果表明,六环石的热稳定性良好,分解温度在600 ℃以上;六环石在PVC糊树脂中的分散状况良好,粒径多数在400 nm左右,微粒为类球形,与基体树脂界面结合良好;当六环石含量为3 %（质量分数,下同）时,复合材料释放空气负离子的浓度可超过1 500个/cm3,达到了世界卫生组织规定的标准。     

不同聚合度PVC树脂的表征和力学性能的研究

采用凝胶渗透色谱仪（ＧＰＣ），差示扫描量热仪（ＤＳＣ）研究不同聚合度ＰＶＣ树脂的分离其分布，玻璃化转变温度（Ｔｇ），考察了加工塑化温度对力学性能的影响。试验结果表明：随着聚合度的提高，ＰＶＣ树脂的分子是增大，分布变宽，Ｔｇ升高，导致材料的加工温度升高，力学性能提高。     

造纸黑液干粉用量对PVC/CPE热塑性弹性体性能的影响

以造纸黑液经硫酸中和处理脱水后的黑液干粉为填料,采用熔融共混法制备了聚氯乙烯(PVC)/氯化聚乙烯(CPE)/黑液干粉热塑性弹性体复合材料。利用FTIR和TGA测试了黑液干粉的结构和热性能;利用微控电子万能试验机、TGA研究了黑液干粉含量对弹性体复合材料的力学性能、热降解性能和老化性能的影响。结果表明:黑液干粉中木质素等有机物含量为33%;添加黑液干粉能改善PVC/CPE弹性体复合材料的力学性能,当黑液干粉含量为30phr时,拉伸强度保持不变,断裂伸长率提高了8%,撕裂强度提高了5%;采用硬脂酸处理的黑液干粉,其用量为30phr时,复合材料综合性能较佳,其拉伸强度提高了7%,断裂伸长率提高了12%,撕裂强度提高了18%;黑液干粉含量30phr时,PVC/CPE弹性体复合材料热降解温度提高了5℃;添加黑液干粉的复合材料,在热氧老化后拉伸强度和邵尔A型硬度增加,断裂伸长率稍有下降。     

可反应性纳米SiO_2对PVC颗粒结构、性能的影响

以VCM和可反应性纳米SiO2(RNS)为原料,采用原位聚合方法合成了PVC/RNS复合材料,考察了RNS对PVC树脂颗粒结构和性能的影响,并利用FTIR和XPS等分析了RNS与PVC之间的相互作用机制。结果表明:①PVC/RNS颗粒内部结构较为疏松多孔,可见较多的初级粒子;②与PVC树脂相比,PVC/RNS复合材料的黏数略有增加,增塑剂吸收量提高,表观密度略有降低,颗粒粒度分布变化不大,维卡软化温度小幅增加,热降解速率降低;③RNS与部分PVC分子链之间形成了强化学键结合。