混合法糊树脂糊粘度影响因素的研究

本从生产工艺、喷雾干燥的工艺条件及干研磨等几方面来研究影响混合法PVC糊树脂糊粘度的原因并研究了降低糊粘度提高树脂质量的方法，     

PVC糊树脂配糊新方法

介绍了一种PVC糊树脂配糊新方法——真空研磨搅拌法,该方法可以降低PVC糊树脂糊料的经时黏度及其变化率。     

掺混树脂对PVC增塑糊性能的影响

研究了掺混树脂的用量对不同型号的PVC糊树脂发泡性能、黏度、力学性能、加工性能等的影响。结果表明:①对于发泡制品,掺混树脂的最佳替代比例为30%(质量分数);②加入掺混树脂可降低PVC增塑糊的黏度,且在放置时间为24h时黏度最大;③加入掺混树脂会降低PVC增塑糊的力学性能和加工性能。     

PVC糊树脂颗粒特性对增塑糊陈化行为的影响

选用5种不同牌号的PVC糊树脂制备出增塑糊,研究了PVC糊树脂的颗粒特性对增塑糊陈化行为的影响。结果表明:①小粒子可填充在大粒子之间,从而降低增塑剂的填充量,自由增塑剂更多,成糊后初始黏度较低;②与紧密型糊树脂相比,松散型糊树脂的增塑糊黏度稳定性更好;③分子质量越大,真实密度越大,增塑糊黏度稳定性越好;④对于紧密型糊树脂,低黏度的增塑糊在陈化过程中大粒子会发生沉降,导致糊中粒子分布不均一。     

十二烷基硫酸钠碳链分布对PVC糊树脂特性的影响

采用不同种类的市售十二烷基硫酸钠作为乳化剂生产PVC糊树脂,研究了十二烷基硫酸钠的碳链分布对PVC糊树脂粒度分布、糊黏度(B式)、72 h增稠率以及标准糊S流动性的影响,设计出适合PVC糊状树脂生产的配方。     

掺混树脂对PVC增塑糊性能的影响

采用PVC糊树脂与掺混树脂复配,研究各复配比例下,掺混树脂对增塑糊初始黏度及黏度稳定性、以及糊制品蒸发残渣性能的影响。结果表明:增塑糊初始黏度随掺混树脂比例的增加而逐渐减小;各体系糊黏度稳定性也相应变差,当CPM-31/SB-100=70/30时,PVC增塑糊的黏度稳定性最差,而CPM-31/SB-100=100/0时的黏度稳定性最好;掺混树脂的加入主要影响PVC糊制品在4%乙酸和正己烷浸泡溶剂下的蒸发残渣性能指标,且当掺混树脂含量为10份后两者残渣结果变化趋势相反。     

低温环境下混合法PVC糊树脂生产的影响因素及控制措施

介绍了混合法PVC糊树脂生产工艺以及低温环境对生产造成的影响,针对低温环境下生产时遇到的种子乳胶破乳、尾气回收系统氧含量超标、喷雾干燥系统结块、糊黏度超标等问题进行了探讨与改进。     

提高PVC糊树脂质量小结

叙述了降低PVC糊树脂产品中氯乙烯残留量、稳定糊黏度的措施。通过改进，提高了产品质量。     

喷雾干燥技术在PVC糊树脂生产中的应用

简单介绍了目前PVC的生产情况,指出PVC糊树脂的市场需求量较大,一些企业准备扩产或对原装置进行改造。详细介绍了喷雾干燥技术在PVC糊树脂生产中的应用情况。     

环保聚氯乙烯增塑糊凝胶性能的研究

采用转矩流变仪和旋转黏度计研究了PVC树脂种类、增塑剂种类、掺混树脂加入量对环保PVC增塑糊凝胶性能的影响规律。结果表明,PVC糊树脂聚合度越大,增塑糊的凝胶化时间越长;颗粒呈规则圆状树脂配制的增塑糊,其凝胶时间相对较长;颗粒呈扁片状的树脂配制的增塑糊,其凝胶时间相对较短。增塑剂与PVC糊树脂相容性越差,增塑糊的凝胶时间越长。随掺混树脂添加量的增多,凝胶时间逐渐延长,当其加入量为40 份（质量份,下同）时,凝胶时间从空白时的18 min延长至28 min。     

PVC糊树脂颗粒形态对糊粘度的影响

利用扫描电镜，分析双峰分布的聚氯乙烯糊树脂初级粒子和次级粒子颗粒形态对糊粘度的影响，结果表明初级粒子表面的乳化剂层包覆不严或表层粉粒太多，均会导致增塑糊粘度偏高；次级粒子聚结松散，结构脆弱，有较低的糊粘度和触变性；次级粒子聚结紧密，有熔结现象，增塑糊粘度偏高。     

残极在电极糊生产中的应用及其对电极糊性能的影响探讨

研究了电极糊配方中添加不同粒度和比例的硬残极对电极糊性能的影响,得出当添加粒度范围为20～8mm,添加比例为20%时,电极糊的耐压强度和体积密度提高程度最大,并有效降低了电阻率和灰分。     

Modelling paste improves

RENSHAPE Solutions, part of Huntsman Advanced Chemicals, has launched an improved version of its seamless modelling paste.This is a short news story only. Visit www.reinforcedplastics.com for the latest plastics industry news.     

聚氯乙烯糊树脂质量的影响因素

对种子乳液法聚氯乙烯糊树脂生产过程中影响糊树脂质量的各种因素进行了分析,总结了目前生产中采取的措施.     

On the properties of freshly made Portland cement paste. Part I. Origins of the colloidal behaviour of cement paste

A freshly made Portland cement paste is a very unusual fluid. It behaves like a colloidal suspension, although cement particles are much coarser than conventional colloid size. The origins of this colloidal behaviour of a cement paste have been traced to high density and high viscosity of the paste itself. Its high density and viscosity hinder the sedimentation of cement grains and allow for the colloid behaviour to develop.     

Decalcification shrinkage of cement paste

Decalcification of cement paste in concrete is associated with several modes of chemical degradation including leaching, carbonation and sulfate attack. The primary aim of the current study was to investigate the effects of decalcification under saturated conditions on the dimensional stability of cement paste. Thin (0.8 mm) specimens of tricalcium silicate (C₃S) paste, white portland cement (WPC) paste, and WPC paste blended with 30% silica fume (WPC/30% SF) were decalcified by leaching in concentrated solutions of ammonium nitrate, a method that efficiently removes calcium from the solid while largely preserving silicate and other ions. All pastes were found to shrink significantly and irreversibly as a result of decalcification, particularly when the Ca/Si ratio of the C-S-H gel was reduced below ∼ 1.2. Since this composition coincides with the onset of structural changes in C-S-H such as an increase in silicate polymerization and a local densification into sheet-like morphologies, it is proposed that the observed shrinkage, here called decalcification shrinkage, is due initially to these structural changes in C-S-H at Ca/Si ∼ 1.2 and eventually to the decomposition of C-S-H into silica gel. In agreement with this reasoning, the blended cement paste exhibited greater decalcification shrinkage than the pure cement pastes due to its lower initial Ca/Si ratio for C-S-H gel. The similarities in the mechanisms of decalcification shrinkage and carbonation shrinkage are also discussed.     

水泥净浆结粒的解决措施

在转型生产P·C42.5水泥后,水泥净浆出现结粒.为消除此现象,某水泥粉磨公司进行技术攻关,采用头脑风暴法和关联图进行逐项分析、排除,确定主要因素为熟料配比高.于是在保证水泥质量前提下降低熟料配比,采取一系列措施,问题得以圆满解决.     

A multi-technique investigation of the nanoporosity of cement paste

The nanometer-scale structure of cement paste, which is dominated by the colloidal-scale porosity within the C-S-H gel phase, has a controlling effect on concrete properties but is difficult to study due to its delicate structure and lack of long-range order. Here we present results from three experimental techniques that are particularly suited to analyzing disordered nanoporous materials: small-angle neutron scattering (SANS), weight and length changes during equilibrium drying, and nanoindentation. Particular attention is paid to differences between pastes of different ages and cured at different temperatures. The SANS and equilibrium drying results indicate that hydration of cement paste at 20 °C forms a low-density (LD) C-S-H gel structure with a range of gel pore sizes and a relatively low packing fraction of solid particles. This fine structure may persist indefinitely under saturated conditions. However, if the paste is dried or is cured at elevated temperatures (60 °C or greater) the structure collapses toward a denser (less porous) and more stable configuration with fewer large gel pores, resulting in a greater amount of capillary porosity. Nanoindentation measurements of pastes cured at different temperatures demonstrate in all cases the existence of two C-S-H structures with different characteristic values of the indentation modulus. The average value of the modulus of the LD C-S-H is the same for all pastes tested to date, and a micromechanical analysis indicates that this value corresponds to the denser and more stable configuration of LD C-S-H. The experimental results presented here are interpreted in terms of a previously proposed quantitative “colloid” model of C-S-H gel, resulting in an improved understanding of the microstructural changes associated with drying and heat curing.     

研磨对EPVC糊性能的影响

介绍了研磨前后EPVC糊黏度的变化情况,结果表明:研磨可增大EPVC糊黏度,随着研磨比例的增大糊黏度逐渐增大,但随着放置时间的延长,研磨前后糊黏度趋于一致。