Gelation and Fusion Characteristics of PVC Resins in Plastisols by Determination of Their Viscoelasticity

Author:

Nakajima N.1,Ward D. W.1

Affiliation:

1. 1BFGoodrich Chemical Group, Avon Lake Technical Center, Avon Lake, Ohio 44012

Abstract

Abstract A poly(vinyl chloride) (PVC) plastisol is a suspension of fine particles of PVC dispersion resin in a plasticizer. The particle size ranges typically from about 15 to 0.2 µm and smaller. The PVC particles in the plastisol consist of the primary particles, which are products of polymerization, and of the agglomerates of the primary particles, which result from the spray drying and subsequent grinding. The commercial applications of plastisols are coatings, films, sheets, foams and rotational castings, where the plastisol is first spread on substrates, and then heated to gel and fuse. PVC dispersion resins are used to produce a variety of formulations, including those for automotive applications, coated fabrics and resilient flooring. Requirements for the plastisols are many; for example, good air release, viscosity stability, fine particle size, foamability and good heat stability. In general, the processability requirements emphasize the rheological behavior at room temperature and the gelation-fusion behavior, the latter being the subject of this paper. When a PVC plastisol is heated, the resin particles are penetrated by the plasticizer and become swollen. Consequently, the system becomes a dry, coherent mass; at this point the material has not attained its ultimate strength. This stage is called gelation. Upon continued heating to a higher temperature (e.g., 195°C) the microcrystallites of PVC melt and the polymer molecules fuse together more uniformly. Upon cooling, the material exhibits the intrinsic strength of a plasticized PVC. The rates of gelation and fusion are important and are often critical aspects of the processing of the plastisol. For example, the rate of gelation controls the residence time needed to build the wall thickness desired in slush molded boots or hot dip molded pieces. Gel rate also affects the uniformity of rotocast parts and the penetration of plastisol into fabric in cast coating operations. Fusion rate and the rate of decrease in melt viscosity after fusion affect uniformity of cells in chemically blown foams. Therefore, many commercial grades of PVC dispersion resins are offered, each having a different rate of gelation, fusion and ultimate properties.

Publisher

Rubber Division, ACS

Subject

Materials Chemistry,Polymers and Plastics

Cited by 14 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. PLASTICIZATION STEPS;Handbook of Plasticizers;2023

2. PLASTICIZATION STEPS;Handbook of Plasticizers;2012

3. Soft PVC foams: Study of the gelation, fusion, and foaming processes. I. Phthalate ester plasticizers;Journal of Applied Polymer Science;2011-03-03

4. Study of the processability of commercial PVC plastisols by rheology;Journal of Vinyl and Additive Technology;1999-03

5. Qualitative model for viscoelastic measurement during gelation and fusion of PVC plastisols;European Polymer Journal;1998-09

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