Gelation of rigid PVC-pipes

Terselius, Björn; Jansson, J.‐F.; Bystedt, Jan

doi:10.1080/00222348108219450

Cited by 24 publications

(24 citation statements)

References 3 publications

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“…The charpy impact performance exhibits a maximum at intermediate DSC real melt temperature (i.e., at intermediate gelation level), which is in accordance with many results reported in the literature. 6,7,8,24 Concerning the comparison of the samples taken parallel or perpendicular to the extrusion direction, a great difference is noticed. At intermediate gelation level, 100% of the breaks of the ''parallel'' series (a) are ''ductile,'' whereas for the ''perpendicular'' series (b), 100% of the breaks are ''brittle,'' whatever the gelation level.…”

Section: Evidence Of the Pvc Anisotropymentioning

confidence: 92%

Thermomechanical history effects on rigid PVC microstructure and impact properties

Fillot

Hajji

Gauthier

et al. 2007

J of Applied Polymer Sci

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Rigid PVC microstructure strongly depends on processing conditions: under both shear and heat influence, gelation process occurs, and the resulting morphology can be characterized by the so-called gelation level parameter. But thermomechanical history also affects several other features of the microstructure. In this work, two different aspects mainly related to (i) orientation and (ii) molecular mobility are pointed out, and their respective effects on poly(vinyl chloride) (PVC) impact properties are described. Charpy impact tests have been carried out on a typical extruded window profile formulation, evidencing a strong anisotropy effect in those extrudates. It turned out that modulated differential scanning calorimetry was able to evidence macromolecular orientation. Then, the effects of heat treatments on impact properties were investigated.Below the glassy transition temperature (T g ) of PVC, physical ageing results in a decrease of the impact performance, without affecting PVC anisotropy. The reason of this performance loss is the reduction of the molecular mobility, as evidenced by dynamical mechanical analysis experiments. After performing a heat treatment above T g , another important decrease of the impact performance was observed. This decrease was attributed to (i) partial disorientation of the PVC macromolecular chains and (ii) reduction of the molecular mobility.

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Section: Evidence Of the Pvc Anisotropymentioning

confidence: 92%

Thermomechanical history effects on rigid PVC microstructure and impact properties

Fillot

Hajji

Gauthier

et al. 2007

J of Applied Polymer Sci

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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%

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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“…In this study the focus will be on the long‐term behaviour of unplasticised poly(vinyl chloride) (uPVC) pipes, which have been used extensively in the gas, water and sewer distribution networks in the Netherlands. Increased knowledge on the stabilisation of uPVC13, 14 and the influence of processing conditions on the mechanical properties,15, 16 has led to prolonged region III and region II failure times. As a result, the long‐term behaviour of the pipes is improved considerably and region I failure has become the limiting region for a wider range of failure times.…”

Section: Introductionmentioning

confidence: 99%

Lifetime Assessment of Load‐Bearing Polymer Glasses: The Influence of Physical Ageing

Visser

Bor

Wolters

et al. 2010

Macro Materials & Eng

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The timescale at which ductile failure occurs in loaded glassy polymers can be successfully predicted using the engineering approach presented in a previous publication. In this paper the influence of progressive physical ageing on the plastic deformation behaviour of unplasticised poly(vinyl chloride) (uPVC) is characterised and incorporated in the existing approach. With the modification it is possible to quantitatively predict long‐term failures which show a so‐called endurance limit. The predictions are compared with failure data of uPVC specimens which were subjected to constant or dynamic loads. In dynamic loading conditions a second type of failure mode was observed: fatigue crack growth. A brief study on the influence of the frequency and stress ratio of the applied stress signal shows that crack growth failure is not expected to occur within experimentally reasonable timescales for constant loading conditions.magnified image

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Gelation of rigid PVC-pipes

Cited by 24 publications

References 3 publications

Thermomechanical history effects on rigid PVC microstructure and impact properties

Thermomechanical history effects on rigid PVC microstructure and impact properties

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

Lifetime Assessment of Load‐Bearing Polymer Glasses: The Influence of Physical Ageing

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