Particle size and molecular weight effects on the melt flow of emulsion PVC

Berens, A. R.; Folt, V. L.

doi:10.1002/pen.760090105

Cited by 56 publications

(19 citation statements)

References 6 publications

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“…The increase in the viscosity of this system depends on the content of the surviving particles; this observation is in agreement with the Berens and Folt model, which shows that particle slippage is favored at a low temperature. 30 The rise of the processing temperature leads to a reduction of the viscosity of the liquid, amorphous phase, and therefore the remaining grains may effortlessly translocate. As a result, a decrease in the friction may be observed, and M X decreases with the temperature.…”

Section: Discussionmentioning

confidence: 99%

Rigid poly(vinyl chloride) gelation in a Brabender measuring mixer. III. Transformation in the torque maximum

Tomaszewska

Sterzyński

Piszczek

2007

J of Applied Polymer Sci

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The processing and structural effects occurring in a poly(vinyl chloride) (PVC) compound processed in a plastograph, at the time at which the maximum value of the torque (point X on the torque curve) was reached, were studied. The unplasticized PVC compound was processed at various temperatures (150-2008C) with a kneader operating at rotors speeds of 5-40 min 21. The changes in the temperature of the compound due to kneading and its influence on the progress of PVC gelation were analyzed. The gelation progress was studied with differential scanning calorimetry, rheological measurements, and scanning electron microscopy. The maximum value of the torque occurred within the temperature range (170-1808C) of the PVC compound, and it was independent of the adjusted temperature of the mixing chamber. The processing of the PVC compound in the kneader, with high mechanical charges and a comparatively low adjusted temperature (150-1708C), spontaneously generated an effect of self-heating, resulting in an increasing temperature of the compound. Despite the surprisingly high degree of gelation (80-98%) of the PVC compound processed under these conditions (as determined by differential scanning calorimetry), the scanning electron microscopy observations indicated significant nonhomogeneity of the fracture surface. Consequently, the kneaded PVC compound at point X of the torque curve could be treated as a two-phase system composed of a liquid, amorphous phase and elements of a grain structure. The transformation of both phases (particularly the quantitative and qualitative changes), which was significantly dependent on the PVC temperature and the shear rate applied by the rotors, determined the state of the melted compound at this point of the torque curve.

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Section: Discussionmentioning

confidence: 99%

Rigid poly(vinyl chloride) gelation in a Brabender measuring mixer. III. Transformation in the torque maximum

Tomaszewska

Sterzyński

Piszczek

2007

J of Applied Polymer Sci

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“…Accordingly at melt processing, the flow of PVC is caused not only by the "uniform flow" by the mutual movement of molecular chains but also by the "particle flow" by the slipping and rolling of particles (primary particles). [1][2][3] The proportion of uniform and particle flow is changed by the degree of gelation and flow conditions. In general, the higher gelation and flow temperature promote uniform flow.…”

Section: Introductionmentioning

confidence: 99%

“…15 Die swell is generally larger when a polymer with a lower DP is extruded at a higher temperature. 2,3,9,12,[17][18][19] A log-log plot of (die swell ratio -1) versus viscosity for extrudates obtained at various extrusion temperatures gives a linear relation with negative slope and the absolute value of the slope increases with increasing DP.…”

Section: Introductionmentioning

confidence: 99%

“…2,3,9,12,[17][18][19] These studies lack in providing a perspective on gelation; however, viewed from the knowledge of the present study, both conditions are in the direction of advancing the gelation and of shifting from particle flow to uniform molecular flow, which can explain the effect of the degree of gelation on the die swell from the concept of the particle and uniform flows. The phenomena and hypothesis that the increase in gelation during extrusion is made more difficult as DP is higher and/or that the feature of the particle flow as against the uniform molecular flow is stronger as DP is higher, at the same level of gelation, are thus elucidated.…”

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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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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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“…These particles, which deform and extend their interchangeable physical ties during flow [13], recover their original shape upon the cessation of shear, as seen from the negligible effects of shear pretreatment in Figure 3. The minimal effects of thermal pretreatment and plasticization, seen in Figures 3 and 4, indicate that the thermoset latex particle flow units are more stable than those of poly(vinyl chloride), which flow with a similar mechanism [1,15], but are more sensitive to temperature and plasticization [18]. Differential scanning calorimetry, dynamic mechanical analysis, and dynamic mechanical spectrometry of two-stage latices prepared using Method B all indicate two distinct TBs, one between -50 and -20 ° C and one at 110 ° C, where the lower transition is a function of the composition of the acrylate mixture used as monomer I.…”

Section: Resultsmentioning

confidence: 86%

Polymer/Polymer Composites Consisting of Interpenetrating Network-Domain Latex Particles

Narkis

Silverstein

1986

Journal of Elastomers & Plastics

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A two-stage emulsion polymerization procedure was used to produce an elastomeric interpenetrating network (IPN)-domain polymer/polymer composite from soft polyacrylates (PAs) and rigid polystyrene (PS), whose thermoset submicron particles contain PS microdomains. The latex particles, the flow units, have a stick, slip, roll flow mechanism through the deformation of the particles and the elongation of their interchangeable physical ties. Neither a Newtonian plateau nor a yield stress was observed at the shear rates and frequencies studied. Two distinct glass transition temperatures ( T g s ) were observed and associated with the individual PA and PS transitions. Transmission electron microscopy (TEM) of a frozen hydrated latex clarified the complex structure of the IPN-domain polymer/polymer particles. The unique mechanical and rheological properties of these materials stem from their IPN-domain structure within the particles as well as from the character of the interparticle interactions.

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Particle size and molecular weight effects on the melt flow of emulsion PVC

Cited by 56 publications

References 6 publications

Rigid poly(vinyl chloride) gelation in a Brabender measuring mixer. III. Transformation in the torque maximum

Rigid poly(vinyl chloride) gelation in a Brabender measuring mixer. III. Transformation in the torque maximum

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

Polymer/Polymer Composites Consisting of Interpenetrating Network-Domain Latex Particles

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