The ‘crystallinity’ of PVC

Ballard, D. G. H.; Burgess, A. N.; Dekoninck, Jm.; Roberts, E. A.

doi:10.1016/0032-3861(87)90312-0

Cited by 49 publications

(31 citation statements)

References 5 publications

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“…Methyl ethyl ketone does not dissolve pPVC probably because of microcrystalline domains of the more regular syndiotactic sequences that are present in PVC. 43,44 On the other hand, specific interactions between carbonyl group CAO of DOP and ClOCH group of PVC 45 can create bridges between the polymer chains. 46 Assuming that such links act as crosslinking nodes, the molecular weight between nodes M c can be determined by the Rehner-Flory equations, 47 from the swelling ratio.…”

Section: Effect Of An Eventual Whiskers Connectivitymentioning

confidence: 99%

Viscoelastic properties of plasticized PVC reinforced with cellulose whiskers

Chazeau

Cavaillé

Canova

et al. 1999

J. Appl. Polym. Sci.

199

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New nanocomposites are processed with a plasticized poly(vinyl chloride) matrix reinforced by cellulose whiskers whose characteristics are a high aspect ratio and a large interface area. Dynamic mechanical analysis performed on samples reinforced with a filler fraction of up to 12.4 vol % gives the viscoelastic properties of the composite above and below its glass transition temperature. Different theoretical predictions are proposed to describe this behavior, but none of them is found wholly satisfactory for describing the reinforcing effect of these fillers. A model based on the Halpin-Kardos equation, with the assumption of an immobilized phase around the whiskers, is developed to account for significant decrease in the modulus drop, on passing above the glass transition temperature. The small discrepancy between this model and the experimental modulus measured in the rubber plateau is discussed as a possible effect of a percolating whisker network whose crosslinks are assured by chains adsorbed onto the whisker surface. Swelling experiments support this hypothesis.

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Section: Effect Of An Eventual Whiskers Connectivitymentioning

confidence: 99%

Viscoelastic properties of plasticized PVC reinforced with cellulose whiskers

Chazeau

Cavaillé

Canova

et al. 1999

J. Appl. Polym. Sci.

199

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“…A strong controversy on the ''crystalline'' nature of this polymer is still open. Evidences of heterogeneous morphology have been reported, [3][4][5][6][7][8][9] but a clear interpretation of the structure is lacking. 1,10,11 On the other hand, PVC undergoes a glass transition and displays dynamical properties like the ␣and ␤-relaxations characteristic for glassforming systems.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous structure of poly(vinyl chloride) as the origin of anomalous dynamical behavior

Arbe

Moral²,

Alegría

et al. 2002

The Journal of Chemical Physics

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Study of the structure and dynamics of poly(vinyl pyrrolidone) by molecular dynamics simulations validated by quasielastic neutron scattering and x-ray diffraction experiments J. Chem. Phys. 134, 054904 (2011); 10.1063/1.3533771 Short-range order and collective dynamics of poly(vinyl acetate): A combined study by neutron scattering and molecular dynamics simulations Comparative study of the relaxation behavior at very low frequencies of acrylate polymers with pendant 1,3dioxane rings in their structureWe have investigated the thermal evolution of the structure and the dynamics of poly͑vinyl chloride͒ ͑PVC͒ in a wide temperature range. Corroborating earlier findings, small angle neutron scattering revealed the presence of structural heterogeneities. On the other hand, the single chain form factor corresponds to that of Gaussian chains. Gradually with increasing temperature the system becomes homogeneous. A simple description of the heterogeneities in terms of microcrystallites is forwarded. The dynamical behavior of PVC has been investigated combining broadband dielectric spectroscopy ͑DS͒ with coherent and incoherent neutron scattering. In a wide temperature range broadband DS facilitated a precise determination of the dynamic response related to the segmental relaxation. Close to the glass transition temperature the line shape strongly deviates from the usual Kohlrausch-Williams-Watts functional form of common glassforming systems. Moreover, the characteristic relaxation time observed by incoherent scattering displays an anomalous dependence on momentum transfer indicating the possible existence of heterogeneities in the sample. Based on the structural and dynamical results, a model is proposed, that considers the coexistence of regions with different dynamical properties leading to a distribution of characteristic relaxation times. The model accounts for the experimental observations, assuming for all regions the same functional form for the ␣-relaxation. It may be univocally determined from the coherent scattering data at the first static structure peak. The distribution of relaxation times found is compatible with the distribution of only one variable, the glass transition temperature.

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“…The low-temperature contribution cannot correspond to the ␤ relaxation that appears at much lower temperature (see next section). Therefore, it could result from the heterogeneity of plasticizer concentration as it has been assumed by several authors, 18,19 and as a first approximation to the presence of two phases with different DOP concentrations (referred to as G Љ maximum1 and G Љ maximum2 in Fig. 5).…”

Section: Heterogeneity In the Ppvcmentioning

confidence: 98%