Measurement of PVC fusion (gelation)

Summers, James W.; Rabinovitch, Elvira B.; Booth, Patrick C.

doi:10.1002/vnl.730080103

Cited by 38 publications

(24 citation statements)

References 16 publications

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“…Although the degree of gelation G reaches a maximum around 200°C, as shown in Figure 5(a), the low-temperature endotherm ⌬Hm(A) continues to increase with the milling temperature, like the entrance pressure loss as shown in Figure 6(a). Terselius et al, 32 Krzewski and Collins, [33][34][35] Patel and Gilbert, 36 Summer and Rabinovitch, 20 and Obande and Gilbert 37 showed that with increasing the processing temperature and hence the gelation of rigid formulation suspension PVC, the entrance pressure loss in the capillary flow increases in an S-shaped fashion. In the present experimental results, although the degree of gelation G shows an S-shaped change [as shown in Fig.…”

Section: Melt Fracturementioning

confidence: 99%

“…Entrance pressure loss is higher as DP and the milling temperature are higher 7,9,20 and the entrance pressure loss of extrudate milled at low extrusion temperatures below 180°C shows only a scarce dependency on DP at reextrusion at low temperatures below about 150°C. 20 The dependency of the entrance pressure loss on the DP of extrudate is weaker than that of the powder.…”

mentioning

confidence: 95%

“…20 The dependency of the entrance pressure loss on the DP of extrudate is weaker than that of the powder. 7 The end correction coefficient, which is a nondimensional measure of the entrance pressure loss, increases with increasing shear rate.…”

mentioning

confidence: 98%

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Effect of degree of polymerization on gelation and flow processability of poly(vinyl chloride)

Fujiyama¹,

Kondou²

2004

J of Applied Polymer Sci

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ABSTRACT:The effect of degree of polymerization (DP) on the gelation and flow processability of poly(vinyl chloride) (PVC) was studied. Sheets with adjusted degree of gelation were prepared by rolling rigid pipe formulation suspension PVC compounds with DPs of 800, 1050 and 1300 by changing the milling temperature. Their degrees of gelation were measured with DSC and their capillary flow properties were measured with a capillary rheometer at 150, 170 and 190°C and the effect of DP on the relation between gelation and flow processabilities was studied. Because of the higher shearing heat during milling, the sample with the higher DP had a higher history temperature and thus tended to show a higher degree of gelation. The viscosity increased as the gelation increased. The dependency of viscosity on DP was higher at higher milling and extrusion temperatures and thus at a higher degree of gelation and a lower shear rate. This was assumed to be attributed to the more prominent uniform molecular flow as against the particle flow. The die swell increased with increasing the milling and extrusion temperatures and hence with increasing the gelation. A sample with a lower DP tended to show a larger die swell and this tendency was even more pronounced at the higher extrusion temperature. The melt fracture easily occurred when a sample with advanced gelation was extruded at low temperature. Whereas at low milling temperatures a sample with the lower DP showed a lower critical shear rate at onset of melt fracture, and thus easily generating melt fracture, at high milling temperatures it showed a higher critical shear rate and hence scarcely generated melt fracture. These experimental results were explained by the fact and concept that a sample with a lower DP shows a higher increase in the gelation during extrusion and/or the slighter feature of particle flow as against the uniform molecular flow at the same gelation level.

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Section: Melt Fracturementioning

confidence: 99%

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confidence: 95%

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Effect of degree of polymerization on gelation and flow processability of poly(vinyl chloride)

Fujiyama¹,

Kondou²

2004

J of Applied Polymer Sci

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“…Several studies1–16 have been reported so far on the effect of gelation (milling) on the flow processability (rheological properties) of PVC. Uryu et al1 studied the effect of milling on the viscosity of rigid‐formulation suspension PVC compounds and showed that the milling generally decreases the viscosity.…”

Section: Introductionmentioning

confidence: 99%

Effect of gelation on the flow processability of poly(vinyl chloride)

Fujiyama

Kondou

2003

J of Applied Polymer Sci

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ABSTRACT:The processing of poly(vinyl chloride) (PVC) consists of fusion, flow, and solidification processes. In this study, we examined how gelation in the fusion process affected the processability in the following flow process. We prepared sheets with adjusted degrees of gelation (Gs) by rolling a rigid-pipe-formulation PVC compound with a degree of polymerization of 1050 by changing the milling temperature and time. The rheological properties, including viscosity, die swell, melt fracture, and entrance pressure loss (⌬P ent ), of the sheets were measured with a capillary rheometer, and the effect of gelation on the flow processability was studied. The viscosity slightly increased as the milling temperature and time increased, and hence, G increased. The flow activation energy showed a maximum at a shear rate around 100 s Ϫ1 and increased with increasing gelation. The die swell was larger when a sheet with a more advanced gelation was extruded at a higher temperature. Melt fracture easily occurred when a sheet with an advanced gelation was extruded at a low temperature. The critical shear rate at the onset of melt fracture changed by over 3 decades, depending on G. ⌬P ent increased linearly with G. The dependence of the rheological properties on the gelation was in the following order: melt fracture Ͼ die swell Լ ⌬P ent Ͼ viscosity: The effect was larger for the elasticity than for the viscosity. The change in these rheological properties with increasing gelation was caused by a transition from particle flow to uniform molecular chain flow.

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“…On the other hand, the PVC particles are broken to the size of PVC primary particles in the well-dispersed domains. The physical properties of the well-dispersed domains have been investigated by several methods, [4][5][6] but no information about the physical properties of the pseudonetwork domains has been reported, since it is difficult to measure the physical properties of the local domain. To design a highly functional polymer, it is desirable to investigate the mechanical properties of the local domains.…”

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confidence: 99%

Morphology and Sound Velocity of Plasticized Polyvinylchloride Studied Using Scanning Acoustic Microscope

Yamada

Koda

Matsuoka

et al. 2001

Jpn. J. Appl. Phys.

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Morphology and sound velocity of plasticized polyvinylchloride were studied using scanning acoustic microscope. Pseudonetwork and well-dispersed domains were observed as acoustic images. The sound velocity of leaky surface skimming compressional waves in the two domains and the intermediate domain were evaluated by analysis of the V (z) curves. The sound velocity in the well-dispersed domains was faster than that in the pseudonetwork domains.

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Measurement of PVC fusion (gelation)

Cited by 38 publications

References 16 publications

Effect of degree of polymerization on gelation and flow processability of poly(vinyl chloride)

Effect of degree of polymerization on gelation and flow processability of poly(vinyl chloride)

Effect of gelation on the flow processability of poly(vinyl chloride)

Morphology and Sound Velocity of Plasticized Polyvinylchloride Studied Using Scanning Acoustic Microscope

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