Crystallinity and mechanical properties of PP-homopolymers as influenced by molecular structure and nucleation

Gahleitner, Markus; Wolfschwenger, Johannes; Bachner, Claudia; Bernreitner, Klaus; Neißl, Wolfgang

doi:10.1002/(sici)1097-4628(19960725)61:4<649::aid-app8>3.0.co;2-l

Cited by 112 publications

(38 citation statements)

References 2 publications

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“…Using real-life injection molding and the resulting parts or specimens, phenomenological work regarding the effects of polymer structure, nucleation, and processing parameters was performed. [151,152] The second approach involved more elementary work regarding the origin of flow-induced nuclei and their development into more or less oriented superstructures. [8,153,154] For the latter part of FIC research, the necessity of developing specific setups and experimental protocols became quickly obvious.…”

Section: Processing-based Modificationsmentioning

confidence: 99%

“…[15,155,156] In retrospect, it is quite interesting to see how many phenomena were discovered through both approaches, sometimes independently. A good example is the significant effect of long molecules, that is, high molecular weight fractions, on skin layer thickness [152] explained by their increased tendency toward formation of nuclei under deformation. [154] The positive effect of high polydispersities on modulus [152] can be explained this way, but also the similar effect of nucleating agents.…”

Section: Processing-based Modificationsmentioning

confidence: 99%

“…A good example is the significant effect of long molecules, that is, high molecular weight fractions, on skin layer thickness [152] explained by their increased tendency toward formation of nuclei under deformation. [154] The positive effect of high polydispersities on modulus [152] can be explained this way, but also the similar effect of nucleating agents. While α-nucleation generally gives higher stiffness, particulate organophosphate types with their high particle anisotropy maximize the modulus as well as the relative thickness of highly oriented skin layers.…”

Section: Processing-based Modificationsmentioning

confidence: 99%

See 2 more Smart Citations

Designing polymer crystallinity: An industrial perspective

Mileva

Tranchida

Gahleitner

2018

Polymer Crystallization

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More than 50% of the thermoplastic polymers applied globally are semi‐crystalline, making crystallization part of the material and component design process for these materials. The mechanical and optical performance, but also the long‐term stability of the final articles and applications will depend upon three major groups of influence factors: Polymer structure and monomer composition, additive addition (especially nucleation) and blending with secondary components, and processing parameters. In the present review, we try to establish a connection between these three areas, the resulting combination of crystallinity and morphology, and the final application properties. Examples are drawn from the two major polyolefins, polyethylene and polypropylene, technical polymers like polyamide and polyester, but also polymers from renewable sources like poly(lactic acid).

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Section: Processing-based Modificationsmentioning

confidence: 99%

Section: Processing-based Modificationsmentioning

confidence: 99%

Section: Processing-based Modificationsmentioning

confidence: 99%

See 1 more Smart Citation

Designing polymer crystallinity: An industrial perspective

Mileva

Tranchida

Gahleitner

2018

Polymer Crystallization

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“…This result correlates with the high graft yield, low MFI, and high melt strength of the blend [7,26,64]. A low MFI is related to higher impact strengths in binary blends [65]. The elastomer phase may experience a large extension of its chains along with a rise in temperature, where a decrease in entropy is opposed by a more energetically favorable random coil conformation [29].…”

Section: Mechanical Propertiesmentioning

confidence: 96%

Morphology and mechanical properties of impact modified polypropylene blends

Tortorella

Beatty

2008

Polymer Engineering & Sci

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Isotactic polypropylene (PP) has been reactively blended with various grades of an ethylene-octene copolymer (EOC) in a twin-screw extruder. Free radical polymerization of styrene and a multifunctional acrylate during melt extrusion has resulted in an enhancement of mechanical properties over the binary blend. The reactive blend exhibits a notched Izod impact strength over 12 times that of pure polypropylene and greater than double the performance of the binary blend. Electron microscopy shows that by grafting onto the polymers, elastomer particle size and interparticle distance decrease, while particle shape becomes less spherical. The acrylate is crucial to achieve superior performance, as infrared spectra correlate an increase in graft yield to improvements in stress-strain behavior and impact strength. In addition, melt flow index (MFI) and melt strength data indicate a reduction in unwanted side reactions of polypropylene and the presence of longchain branching. Dynamic-mechanical analysis reveals that the reaction promotes miscibility between polypropylene and the EOC and reduces molecular mobility at their glass-transition temperatures. Mechanical properties, graft yield, and MFI are shown to be highly dependent upon the elastomer's concentration, density, and molecular weight, initiator and monomer concentration, as well as processing temperature.

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“…There are many articles reporting on nucleated PP. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Nucleating agents not only increase the mechanical properties of PP, but also shorten the cycle time of production. Although many of nucleating agents are used in practice, most of nucleating agents are discovered empirically.…”

Section: Introductionmentioning

confidence: 99%

Isothermal crystallization behavior and melting characteristics of injection sample of nucleated polypropylene

Wang

Mai²,

Zeng

2000

J. Appl. Polym. Sci.

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The isothermal crystallization behavior and melting characteristics of pure polypropylene (PP) and PPs nucleated with a phosphate nucleating agent (A) and a sorbitol derivative (D) have been studied by differential scanning calorimetry (DSC). Compared with pure PP, nucleated PPs show a shorter half-times of crystallization. Dependence of crystallization rate of nucleated PP on the crystallization temperature is stronger than that of pure PP at the higher crystallization temperature, whereas the opposite results are obtained at the lower crystallization temperature. Addition of nucleating agent shifts the temperature at the deviation from the baseline of DSC melting curve, T m o , and the temperature at the completion of melting, T m f , to higher temperatures, indicating that nucleated PPs exhibit a higher perfection of PP crystals. A shoulder peak in the high temperature range of melting peak of nucleated PP and a wider low temperature region in the melting peak of pure PP are observed. Obviously, PP and nucleated PPs form different distribution of crystal perfection in the isothermal crystallization process. According to the half-time of crystallization, nucleating agent A is more effective than D.

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Crystallinity and mechanical properties of PP-homopolymers as influenced by molecular structure and nucleation

Cited by 112 publications

References 2 publications

Designing polymer crystallinity: An industrial perspective

Designing polymer crystallinity: An industrial perspective

Morphology and mechanical properties of impact modified polypropylene blends

Isothermal crystallization behavior and melting characteristics of injection sample of nucleated polypropylene

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