Effect of injection molding parameters on crystallinity and mechanical properties of isotactic polypropylene

Rizvi, S. J. A.

doi:10.1007/s12588-017-9194-3

Cited by 30 publications

(37 citation statements)

References 13 publications

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“…Many parameters associated with the various process steps are involved ( Chen and Turng, 2005 ), including melt processing temperature, mold temperature, injection flow rate, and holding pressure ( Bociaga, 2000 ; Heidari et al, 2019 ). The polymer is therefore subjected to a set of thermomechanical conditions, which result in modification of its intrinsic properties ( Fu et al, 2005 ; Rizvi, 2017 ). As a result of the multi-step process, changes in the strength and consequently morphological and structural variations take place ( Mohan et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Scanning acoustic microscopy investigation of weld lines in injection-molded parts manufactured from industrial thermoplastic polymer

Mohamed

Zhai

Schneider

et al. 2020

Micron

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Section: Introductionmentioning

confidence: 99%

Scanning acoustic microscopy investigation of weld lines in injection-molded parts manufactured from industrial thermoplastic polymer

Mohamed

Zhai

Schneider

et al. 2020

Micron

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“…Normally, the variation in T m influences the crystallinity, which in turn influences the tensile properties [16,17]. In this study, even though the crystallinity found (Sect.…”

Section: Tensile Testsmentioning

confidence: 49%

“…9 Main effects plot for the impact strength This was not the case for a T i of 240 °C. Different phenomena might have contributed to these results, among them crystallinity morphology, spherulite sizes and higher molecular orientations [16,17]. For instance, Rizvi [17] associated the decrease in impact strength of his pure iPP, when increasing T m , to the increase of crystallite size.…”

Section: Tensile Testsmentioning

confidence: 99%

Adjusting process parameters in zamak-8 prototype tooling to obtain functional prototypes in PP

Volpato

Junkes

2020

J Braz. Soc. Mech. Sci. Eng.

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Prototype tooling is an option to obtain functional prototypes, or even final parts, in low-scale injection molding. In order to reduce the manufacturing time and cost of this type of tooling, alternative materials, such as zinc alloys, can be employed. However, the mold material and injection parameters can influence molding crystallinity and mechanical properties. The zinc alloy known as zamak-8 has not been explored much for this application. The objective of this work is to study the influence of this mold material on the properties of polypropylene (PP) when varying the mold (T m) and injection (T i) temperatures. Then, based on that, to develop some regression models to help obtain PP moldings in the zamak-8 mold with similar characteristics to those injected in a steel mold, which was used as a reference, the characterization techniques used were tensile and impact tests, and differential scanning calorimetry as well, to measure crystallinity. The results showed that zamak-8 prototype tooling only has a significant influence on the impact strength of the injected PP. The regression models showed that to obtain injected prototypes with mechanical and crystalline properties close to a production part in this specific study, T m should be set at around 40 °C and T i at 225 °C. In general, this indicates that zamak-8 can be used to obtain functional prototypes in PP with similar properties to the production parts.

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“…α-phase is characteristic of most of the parts of the molded samples, since it is the most stable one, whereas β-phase is thermodynamically metastable, and more difficult to be found [19]. The high shear stresses experienced by the polymer chains during the injection molding process mainly induces the transformation of β-phase into α-phase [20]. However, the β-phase formation is highly desired, since it enhances the toughness of the molded samples.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Structure of iPP During Injection Molding Process with Fast Mold Temperature Evolution

et al. 2019

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Mold surface temperature strongly influences the molecular orientation and morphology developed in injection molded samples. In this work, an isotactic polypropylene was injected into a rectangular mold, in which the cavity surface temperature was properly modulated during the process by an electrical heating device. The induced thermo-mechanical histories strongly influenced the morphology developed in the injection molded parts. Polarized optical microscope and atomic force microscope were adopted for morphological investigations. The combination of flow field and cooling rate experienced by the polymer determined the hierarchical structure. Under strong flow fields and high temperatures, a tightly packed structure, called shish-kebab, aligned along the flow direction, was observed. Under weak flow fields, the formation of β-phase, as cylindrites form, was observed. The formation of each morphological structure was analyzed and discussed on the bases of the flow and temperature fields, experienced by the polymer during each stage of the injection molding process.

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Effect of injection molding parameters on crystallinity and mechanical properties of isotactic polypropylene

Cited by 30 publications

References 13 publications

Scanning acoustic microscopy investigation of weld lines in injection-molded parts manufactured from industrial thermoplastic polymer

Scanning acoustic microscopy investigation of weld lines in injection-molded parts manufactured from industrial thermoplastic polymer

Adjusting process parameters in zamak-8 prototype tooling to obtain functional prototypes in PP

Hierarchical Structure of iPP During Injection Molding Process with Fast Mold Temperature Evolution

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