Plastisols of poly(vinyl chloride); particle size distribution, morphology, rheology, and mechanism of aging

Nakajima, Nobuyuki; Daniels, Charles A.

doi:10.1002/app.1980.070250918

Cited by 40 publications

(28 citation statements)

References 4 publications

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“…2 The commercial resin, unfractionated, was designated as the raw feed, RF, which was air-classified into five different size fractions. The finest fraction, FF, and the coarsest one, 4C, were used in this report singly or as blends of these two in different proportions.…”

Section: Pvc Dispersion Resin Samplesmentioning

confidence: 99%

“…This is in good agreement with the size of the fine particle resin powder, which had a median diameter of 0.65-0.73 ,um. 2 The corresponding median size of the swollen particle is 0.80-0.90 ,urn. (v) At 154-1600C the fusion is almost complete and no particulate structure is visible.…”

Section: Morphologymentioning

confidence: 99%

“…1 The oscillatory measurements were also carried out to characterize the dynamic responses. 2 On the other hand, less attention was paid to the effect of particle size and size distribution on gelation and fusion. Since gelation and fusion are also important steps in plastisol processing, we have undertaken this study.…”

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Dependence of Gelation and Fusion Behavior of Poly(vinyl chloride) Plastisols upon Particle Size and Size Distribution

Nakajima¹,

Isner²,

Harrell³

et al. 1981

Polym J

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ABSTRACT:Poly(vinyl chloride) (PVC) plastisol is a suspension of small particles of PVC resin in plasticizer. The processing of plastisol typically involves flow at room temperature during coating or mold filling, and gelation and fusion as the plastisol is heated to form the final product. This paper explores the effect of the particle size distribution on the gelation and fusion behavior. For this purpose a commercial PVC resin was air-classified into fractions of different particle size. Samples were then reconstituted to have known particle size distributions. Particular emphasis is placed on the effect of the fine particle fraction on the material behavior. The progress of gelation and fusion were followed by measurement of the viscoelastic properties as a function of treatment temperature using a mechanical spectrometer. Characteristic changes in the viscoelastic behavior were associated with changes in morphology, observed with a scanning electron microscope, enabling qualitative discrimination of the gelation and fusion processes. The larger fraction of fine particles gave higher values of G' and G". It seems that the fine particles promote the interparticulate bonding, when the particles start fusing together.KEY WORDS Poly(vinyl chloride) I Plastisol I Particle Size Distribution I Gelation-Fusion I Particulate Morphology I Viscoelastic Properties 1 Both the average particle size and the particle size distribution of poly(vinyl chloride) (PVC) dispersion resins have been recognized as important material variables pertinent to PVC plastisol behavior. The flow behavior at room temperature is profoundly influenced by these variables. Therefore, they are important in regard to processability. The types of flow behavior encountered in these systems, such as thixotropy, shear-thinning and dilatancy have been investigated previously. 1 The oscillatory measurements were also carried out to characterize the dynamic responses. 2 On the other hand, less attention was paid to the effect of particle size and size distribution on gelation and fusion. Since gelation and fusion are also important steps in plastisol processing, we have undertaken this study. gelation and fusion. 5 These observations elucidated the mechanism of the diffusion of plasticizer into resin particles, the presence and disappearance of particulate structure and the temperature range of the melting of the PVC crystallites. In addition, the progress of interparticle bonding was postulated to explain the accompanying development of mechanical strength.Our previous studies demonstrated the effectiveness of viscoelastic measurements for characterizing gelation and fusion behavior. 3 -5 Morphology was also examined of samples taken at different stages of When the plasticizer is taken up by the resin particles, a large amount of interparticle voids are present; these voids disappear, of course, when the particulate structure disappears. However, some defects are present up until the fusion is complete; the latter state is reached when the mechanical ...

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Section: Pvc Dispersion Resin Samplesmentioning

confidence: 99%

Section: Morphologymentioning

confidence: 99%

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Dependence of Gelation and Fusion Behavior of Poly(vinyl chloride) Plastisols upon Particle Size and Size Distribution

Nakajima¹,

Isner²,

Harrell³

et al. 1981

Polym J

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“…The agglomerates are not necessarily spherical, and their shape and morphology were reported before. 7,8 In the microscopic views, a plastisol is shown to be very crowded with particles. 7,8 There had never been an attempt to elucidate the flow mechanism of PVC plastisol, until Hoffman discovered an immobilized layer of PVC particles developed with the increase of shear rate.…”

Section: Introductionmentioning

confidence: 98%

Normal stresses in flow of polyvinyl chloride plastisols

Nakajima

Harrell²

2006

J of Applied Polymer Sci

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In the steady state flow of many liquids, such as polymer solutions and melts, the first normal stress difference, N 1 ¼ s 11 À s 22 , is positive. However, with liquid crystal systems and some colloidal suspensions, negative values of N 1 were reported in literature. In our past work with a commercial polyvinyl chloride plastisol, negative values were observed. During the steady state flow, the plastisol undergoes stress-induced phase separation into an immobilized layer and a mobile phase. The concentration difference between the two phases gives a rise to an osmotic pressure difference, Dp, which is countered by a normal stress, N, generated by the flow. Because N is balanced with Dp, N cannot be observed directly. In this work, N is identified as an isotropic and N 1 , directional. The disturbance among rotating particles in the mobile phase produces two effects; one is an increase of pressure, which is N; the other, N 1 is associated with a small volume increase, which is directed towards the opening of the rheometer. The directional expansion is caused by the shearstress gradient in the liquid between the rotating particles.

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“…The ground particles are nonspherical. 3 The resin particle contains emulsifier (used for polymerization), the type of which affects performance of the plastisol. 4 The rheology of plastisol processing encompasses two aspects.…”

Section: Introductionmentioning

confidence: 99%

Rheology of poly(vinyl chloride) plastisol for super‐high‐shear‐rate processing. II

Nakajima

Harrell²

2011

J of Applied Polymer Sci

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Capillary flow of poly(vinyl chloride) plastisol was examined at low, high, and superhigh shear rates. At the low to intermediate shear rates, the flow was pseudo-plastic, but the measured viscosity was not reproducible and widely scattered. The flow behavior was explained as the breakup of the particle network into network-fragments of varying size. At high shear rates, the measured viscosity was reproducible and increased with shear rate, indicating that the particles were, by and large, separated from each other. At superhigh shear rates, the viscosity decreased with the increase of shear rate. The particles cease to participate in flow because rotation becomes more difficult. A plug-flow ensues with a thin layer of lubricating plasticizer.

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Plastisols of poly(vinyl chloride); particle size distribution, morphology, rheology, and mechanism of aging

Cited by 40 publications

References 4 publications

Dependence of Gelation and Fusion Behavior of Poly(vinyl chloride) Plastisols upon Particle Size and Size Distribution

Dependence of Gelation and Fusion Behavior of Poly(vinyl chloride) Plastisols upon Particle Size and Size Distribution

Normal stresses in flow of polyvinyl chloride plastisols

Rheology of poly(vinyl chloride) plastisol for super‐high‐shear‐rate processing. II

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