Multiple melting behavior of nucleated polypropylene

Mai, Kancheng; Wang, Kefeng; Zeng, Hanmin

doi:10.1002/app.11652

Cited by 15 publications

(6 citation statements)

References 46 publications

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“…Even though a triple DSC melting peak appeared in Figure b, a new crystal structure was not generated. The peculiar DSC triple melting peak may be attributed to the existence of less close-packed crystals in this foaming condition. ,− When the samples were exposed to 10.3 MPa CO 2 pressure, the relative intensities of the neat PLA, PLA-1C, and PLA-5C at 2θ = 16.7° almost disappeared, indicating very low crystallinities in these samples. When the fibers content was increased to 10, 20, and 30 wt %, relative diffraction intensities of 2θ = 16.7, 19.0, and 22.3° were detected.…”

Section: Results and Discussionmentioning

confidence: 97%

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Zhang

Ding

Zhao

et al. 2018

Ind. Eng. Chem. Res.

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The foaming behavior and thermal properties of neat polylactide (PLA) and PLA/cotton-fiber composite foams were investigated in this study. CO2 saturation pressure, temperature, and fibers content significantly affected PLA’s crystallinity and foaming behaviors. At the same saturation temperature (140 °C), a low CO2 pressure generated nonuniform foam and a large unfoamed area due to too high crystallinity with a close-packed structure. At an intermediate pressure, a fine-cell structure was developed due to the presence of numerous less closely packed crystals served as cell nucleating agents. A high CO2 pressure also led to a uniform cell structure but with larger cell sizes due to cell deterioration. Similar to the effect of saturation pressure, an intermediate temperature generated the uniform fine-cell structures. The PLA’s cell morphology was improved by the addition of cotton fibers at a low content because of the increased local stresses through the fibers and transcrystals surrounding the fibers.

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Section: Results and Discussionmentioning

confidence: 97%

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Zhang

Ding

Zhao

et al. 2018

Ind. Eng. Chem. Res.

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“…Irrespective of the mold temperature, there are two melting peaks existed in DSC scanning curves, labeled as I and II for low and high temperature melting peaks, respectively. The multiple melting behavior of semicrystalline polymers has been investigated extensively31–33 and the models proposed include (1) the presence of more than one crystallographic form, (2) the presence of melting, recrystallization and remelting, and (3) changes in morphology, such as lamella thickening and crystal perfecting 34, 35. In our previous study,3 the multiple melting behavior of PA6 was investigated in detail by means of XRD measurement and the corresponding results revealed that the different peaks do not represent the melting of different PA6 crystal forms.…”

Section: Resultsmentioning

confidence: 99%

Double yielding in PA6: Effect of mold temperature and moisture content

Shan

Yang

Tang

et al. 2007

J Polym Sci B Polym Phys

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In this study we have investigated the effect of mold temperature and moisture content on double yielding of virgin polyamide 6 (PA6) uniaxially deformed at room temperature. The experimental results have revealed that, to a certain extent, a limited increment in both mold temperature and moisture content will make the second yield process become more apparent. However, the double yielding behavior will disappear totally in the case of much higher mold temperature and moisture content. Instead, a typical single sharp yield or brittle fracture will be present in the former case, while in the latter case the samples only display a very broad yield, similar to a rubber-like deformation. Maybe two critical states will be in existence in PA6 exhibiting double yielding behavior, and the critical states are probably relevant with the concentration of the interlinks and intralinks, the lamellae perfection and the crystallite size. Particular emphasis should be placed on the role of interlinks and intralinks when considering the origin of double yielding of virgin PA6 since these links affect the stress transfer significantly.

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“…This interpretation is also supported by the fact that this small shoulder is not observable during the first heating ramp ( Figure S5 in Supplementary Materials ). Many authors have encountered this phenomenon [ 59 , 60 ].…”

Section: Resultsmentioning

confidence: 99%

Antibacterial Textile Based on Hydrolyzed Milk Casein

et al. 2021

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Antimicrobial textile structures are developed based on polypropylene (PP) and a natural material, hydrolyzed casein. The casein, from bovine milk, is subjected to acid hydrolysis in aqueous media, then blended into the PP matrix in the melt phase by extrusion. The obtained blend, containing 5 wt.% of hydrolyzed casein, is then processed by a melt spinning process to get multifilaments, leading to the production knitting structures. Thanks to the addition of the hydrolyzed casein, the obtained textile showed a strong antibacterial activity towards both Gram (+) and Gram (−) bacterial strains. The addition of 5 wt.% hydrolyzed casein does not significantly impact the mechanical properties of PP in the dumbbells form, but a small decrease was observed in the tenacity of the filaments. No moisture retention was observed after the addition of hydrolyzed casein, but the rheological behavior was slightly affected. The obtained results can contribute to addressing concerns regarding nonrenewable antibacterial agents used in textile materials, particularly their effects on the environment and human health, by offering antibacterial agents from a biobased and edible substance with high efficiency. They are also promising to respond to issues of wasting dairy products and recycling them, in addition to the advantages of using melt processes.

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Multiple melting behavior of nucleated polypropylene

Cited by 15 publications

References 46 publications

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Double yielding in PA6: Effect of mold temperature and moisture content

Antibacterial Textile Based on Hydrolyzed Milk Casein

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Multiple melting behavior of nucleated polypropylene

Cited by 15 publications

References 46 publications

Effects of Compressed CO2 and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Effects of Compressed CO2 and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Double yielding in PA6: Effect of mold temperature and moisture content

Antibacterial Textile Based on Hydrolyzed Milk Casein

Contact Info

Product

Resources

About

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide

Effects of Compressed CO₂ and Cotton Fibers on the Crystallization and Foaming Behaviors of Polylactide