Crystallization Behavior in Poly(propylene) Containing Wollastonite Microfibrils

Saujanya, C.; Tangirala, Ravisubhash; Radhakrishnan, S.

doi:10.1002/1439-2054(20020401)287:4<272::aid-mame272>3.0.co;2-j

Cited by 12 publications

(8 citation statements)

References 10 publications

(11 reference statements)

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“…All of these parameters are related to the crystallization behavior of polymer and its dependence on the incorporation of different additives in the polymer together with the processing conditions used for molding. Many studies have been reported in the past, including by the present authors, on the crystallization behavior of PP containing wide ranges of additives 5–12. These studies showed that large changes occur on the induction time, crystallization half‐time, spherulite size, etc., due to the presence of additive.…”

Section: Introductionsupporting

confidence: 53%

“…The main diffraction angle (2θ) region of interest (5 to 30°) only has been shown in which PP exhibits five intense peaks. It can be recognized that, in all these cases, the crystalline structure of PP is α‐type (monoclinic a = 6.66 Å, b = 20.8 Å, c = 6.49 Å, and β = 99.6) 4, 5, 11–13. However, it can be noted that the relative intensities of these peaks depend on both the composition and the cooling rate used.…”

Section: Resultsmentioning

confidence: 96%

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Effect of thermal conductivity and heat transfer on crystallization, structure, and morphology of polypropylene containing different fillers

Radhakrishnan

Sonawane

Pawaskar

2004

J of Applied Polymer Sci

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ABSTRACT:The crystallization behavior, structure, and morphology developed was investigated for polypropylene containing different fillers such as silica, calcium carbonate, talc, mica, graphite, etc. by using compression-molded samples prepared at several cooling rates. It was observed that the crystallinity obtained for any given composition depended on the thermal conductivity of the filler and the PP composite containing it as well as the cooling rate to which it was subjected. These composites exhibited skin-core type of morphology and the skin layer thickness was found to depend not only on the cooling rate but also on the type of filler, its thermal conductivity, etc. These various experimental findings were discussed in light of the phenomenological model described in our earlier work, which correlates thermal conductivity and degree of crystallinity for various compositions of PP containing additives.

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Section: Introductionsupporting

confidence: 53%

Section: Resultsmentioning

confidence: 96%

Effect of thermal conductivity and heat transfer on crystallization, structure, and morphology of polypropylene containing different fillers

Radhakrishnan

Sonawane

Pawaskar

2004

J of Applied Polymer Sci

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“…The increase in X c of iPP with the fillers might be due to local crystallinity formation around the filler particles. An increase in crystallinity of iPP matrix with GB [61, 86–89] and W [36, 73–76, 90–94] was reported previously. Yuan et al [87–89] found that β‐crystal formation of iPP increased with increasing GB content and decreasing GB size because of an increase in GB surface area acting as nucleation site for β‐crystals.…”

Section: Resultssupporting

confidence: 57%

“…This might be due to a higher specific surface area of acicular W than that of spherical GB (Table 1). An increase in T c of iPP with GB [21, 23, 61, 78, 88, 97] and W [73–76, 90, 92, 93] due to the enhanced nucleation was reported earlier. Stricker and Mülhaupt [21, 23] found that GB nucleated iPP matrix as evidenced by increasing T c of iPP with GB although X c of iPP remained unchanged with GB.…”

Section: Resultsmentioning

confidence: 64%

Microstructural characteristics of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Balkan

Demirer

2009

Polymer Composites

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Microstructural characteristics of isotactic-polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, poly(styrene-b-ethylene-co-butylene-b-styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS-g-MA), were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA) showed that the iPP/SEBS and iPP/SEBS-g-MA blends were partially compatible two-phase systems. Well-dispersed spherical GB and acicular W particles without evidence of interfacial adhesion were observed in the iPP/GB and iPP/W binary composites respectively. Contrary to the blends, melt flow rates of the iPP/GB and PP/W composites decreased more with SEBS-g-MA than with SEBS because of enhanced interfacial adhesion with SEBSg-MA elastomer. The SEM analyses showed that the ternary composites containing SEBS exhibited separate dispersion of the rigid filler and elastomer particles (i.e., separate microstructure). However, SEBS-g-MA elastomer not only encapsulated the spherical GB and acicular W particles completely with strong interfacial adhesion (i.e., core-shell microstructure) but also dispersed separately throughout iPP matrix. In accordance with the SEM observations, the DSC and DMA revealed quantitatively that the rigid filler and SEBS particles in iPP matrix acted individually, whereas the rigid filler particles in the ternary composites containing SEBS-g-MA acted like elastomer particles because of the thick elastomer interlayer around the filler particles. The Fourier transform infrared analyses revealed an esterification reaction inducing the strong interfacial adhesion between the SEBS-g-MA phase and the filler particles. POLYM. COMPOS.FIG. 12. Storage modulus (E 0 ) and damping factor (tan d) variations of the ternary composites as a function of temperature.

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“…In most of these studies, the emphasis was placed on the nucleation, preferential growth, and so forth 6–10. However, it is well known that the rate of cooling plays an important role in determining the crystallinity and/or morphology obtained in the final product made by melt processing 11. Because the thermal conductivity of the filler and that of the composite containing that filler are important factors governing the heat‐transfer process, we felt that a systematic investigation into the role of thermal conductivity in the crystallization of PPs containing different fillers would lead to a better understanding of these phenomena.…”

Section: Introductionmentioning

confidence: 99%

Role of heat transfer and thermal conductivity in the crystallization behavior of polypropylene‐containing additives: A phenomenological model

Radhakrishnan¹,

Sonawane²

2003

J of Applied Polymer Sci

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ABSTRACT:The thermal conductivity of a filler and the thermal conductivity of a composite made from that filler influence the heat-transfer process during melt processing. The heat-transfer process from the melt to the mold wall becomes an important factor in developing the skin-core morphology. These aspects were examined in this study. The thermal conductivity of polypropylene-filler composites was estimated with a standard model for various fillers such as calcium carbonate, talc, silica, wollastonite, mica, and carbon fibers. The rate of cooling under given conditions, including the melting temperature, mold wall temperature, mass of the composite, and filler content, was estimated with standard heat-transfer equations. The time to attain the crystallization temperature for polypropylene was evaluated with a regression method with differential temperature steps. The crystallization curves were experimentally determined for the different fillers, and from them, the induction period for the onset of crystallization was estimated. These observations were correlated with the expected trends from the aforementioned formalism. The excellent fit of the curves showed that in all these cases, the thermal conductivity of the filler and composite played a dominant role in controlling the onset of the crystallization process. However, the nucleation effects became important in the later stages after the crystallization temperature was attained.

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Crystallization Behavior in Poly(propylene) Containing Wollastonite Microfibrils

Cited by 12 publications

References 10 publications

Effect of thermal conductivity and heat transfer on crystallization, structure, and morphology of polypropylene containing different fillers

Effect of thermal conductivity and heat transfer on crystallization, structure, and morphology of polypropylene containing different fillers

Microstructural characteristics of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Role of heat transfer and thermal conductivity in the crystallization behavior of polypropylene‐containing additives: A phenomenological model

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