Infrared studies of crystallinity in poly(vinyl chloride)

Witenhafer, D. E.

doi:10.1080/00222347008217132

Cited by 63 publications

(12 citation statements)

References 4 publications

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“…In a commercial PVC, distinct crystalline regions (i.e., microcrystallites) exist because of the presence of syndiotactic sequences of between 5 and 12 ordered monomer units 14 · 15 along the chain, which are responsible for approximately 8-10% of crystallinity.16·17 It has been suggested that the PVC microcrystallites are not completely melted within normal processing temperature of PVC due to the wide melting range of 120--210°C. 18 As the microcrystallites melt, restrictions to molecular mobility decreases, and this results in the shift of the log G"(w)-496 logG'(w) plots to the left. In both systems, especially in PVC/NBR-22, the magnitude of the shift to the left is different at individual temperature range, which suggests that there are substantially differences in the amount of the microcrystallites corresponding to the individual temperature range.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Kwak

1994

Polym J

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ABSTRACT:In the present study, dynamic shear oscillation measurements at small strain were conducted on four model blends of equal amounts (50/50 by weight) of poly(vinyl chloride) (PVC) with three compatible and one incompatible polymers. The compatible polymers were nitrile rubber containing 30% acrylonitrile (NBR-30), poly(B-caprolactone) (PCL), and copolyester thermoplastic elastomer (trademark HYTREL). The incompatible one was nitrile rubber containing 22% acrylonitrile . Double logarithmic plots of loss modulus G"(w) against storage modulus G'(w) were employed as a systematic, practical way of treating the data. The JogG"(w)-logG'(w) scheme was shown to enable one to characterize and interpret the viscoelastic behavior of the blends related to the mixing history and morphological changes.KEY WORDS Poly(vinyl Chloride) (PVC) / Nitrile Rubber (NBR) / Poly-(B-caprolactone) (PCL) / Copolyester Thermoplastic Elastomer (HYTREL) / Mechanical Blending/ Viscoelastic Behavior/ Shear Storage Modulus G'(w) / Shear Loss Modulus G"(w) / log G"(w)-log G'(w) Plot/ Dynamic mechanical measurements have been used for characterizing a wide range of polymeric materials. Common features of the dynamic mechanical measurements are to impose a periodic, uniform sinusoidal deformation on a specimen and then observe the storage (elastic) and loss (viscous) moduli of.the specimen.Dynamic mechanical analysis may be classified into two categories; the first is associated with the measurements involving free vibrations and in the second are those based on forced oscillations. 2 • 3 Among those falling in the second category, the dynamic shear oscillation measurement at small strain has been used to not only characterize the viscoelastic properties but also relate them to identify the differences in molecular structure and predict the behavior during processing. It is thus one of the most powerful techniques for studying the effect of not only molecular structure but also phase morphology on the physical properties and determining the processability and product performance, both of which are essential in component design.Among the dynamic viscoelastic parameters measured at small strain in shear oscillation, the shear storage modulus G' and shear loss modulus G" are of typical importance especially when elastic and viscous responses are needed to be rigorously separated. Both the storage and loss moduli can be obtained either as a function of temperature (at constant frequency; isochronal) or as a function of frequency (at constant temperature; isothermal).

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Section: Discussionmentioning

confidence: 99%

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Kwak

1994

Polym J

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“…The commercial PVC is an atactic polymer, which has syndiotactic blocks. Because of the distribution of the block length, melting range of the microcrystal is from 120 to above 200 C [7]. The thermal stability of PVC deteriorates rapidly at above 200 C. Therefore, the highest temperature of processing is about 200 C. This means at the processing condition some microcrystallites are present.…”

Section: Polyvinylchloride Pvcmentioning

confidence: 98%

Polymer Processing Problems from Non-Rheological Causes¹

Nakajima

1999

International Polymer Processing

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There are a variety of problems in polymer processing. In this paper those problems which arise from non-rheological causes are described. The examples were taken from the period from 1960 to 1970's. Even though remedial steps were taken at the time when problems occurred, similar problems may occur in the future. The problems are well-known among those who worked in the area, but may not be known widely, because very few have ever been published.Some of the problems may be eliminated in the course of improving polymerization and fabrication (processing) techniques. Some problem-solving will become easier with the improvement of sensitivity of analytical techniques. Some problems merit further scientific studies. Many problems provide seeds for inventions.

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“…The name given to a PVC–plasticizer dispersion is PVC paste or plastisol . Since PVC has a crystallinity of about 10%, a wide melting temperature range due to small imperfect crystallites and a glass transition temperature of about 80 °C, PVC plastisols are used to produce a number of commercially important end products, such as safety floorings, synthetic leather products, textile inks for printing, coatings, wall‐coverings, and moldings, when plastisol is converted from liquid to solid through a curing process . The curing process involves heating so PVC can absorb plasticizer and enable fusion or disappearance of PVC primary microcrystallites; on cooling, secondary crystallinity, which produces physical crosslinks in PVC, can be formed , .…”

Section: Introductionmentioning

confidence: 99%

Dielectric and electromechanical studies of plasticized poly(vinyl chloride) fabricated from plastisol

Ali

Ueki

Hirai

et al. 2013

Polymer International

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Poly(vinyl chloride) (PVC) plastisol is used in many industrial applications and is considered an electrically inactive material. To explore the potential of plastisol as an electroactive material, the dielectric properties, space charge distribution, mechanical properties, internal structure and electromechanical behavior of plasticized PVC (PVC gel) prepared from plastisol by heating were investigated. The gel exhibited a large dielectric constant at low frequencies (1–1000 Hz), an asymmetric charge distribution and excellent mechanical properties. Various DC electric fields were applied to the gel placed parallel between two electrodes and the electrostatic adhesive force to the anode was measured. The results of small‐ and wide‐angle X‐ray scattering suggested that the electromechanical properties of the gel originated from the characteristics of the physical crosslinking distance (ca 20 nm) of PVC in the gel structure. Considering the dielectric properties, space charge density and adhesion force to the anode, PVC gels prepared from plastisol using the heating method have potential for use as electroactive materials. © 2013 Society of Chemical Industry

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Infrared studies of crystallinity in poly(vinyl chloride)

Cited by 63 publications

References 4 publications

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Polymer Processing Problems from Non-Rheological Causes¹

Dielectric and electromechanical studies of plasticized poly(vinyl chloride) fabricated from plastisol

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Infrared studies of crystallinity in poly(vinyl chloride)

Cited by 63 publications

References 4 publications

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Dynamic Viscoelastic Behavior of Model Poly(vinyl chloride) Blends Characterized at Small Deformation in Shear Oscillation

Polymer Processing Problems from Non-Rheological Causes1

Dielectric and electromechanical studies of plasticized poly(vinyl chloride) fabricated from plastisol

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Polymer Processing Problems from Non-Rheological Causes¹