Crystallinity enhancement of extruded polypropylene containing poly(vinyl alcohol) fibers prepared in situ

Nishikawa, Riho; Eno, Ayaka; Janchai, Khunanya; Han, Ruiqi; Kida, Takumitsu; Mori, Toyoichiro; Aridome, Norifumi; Miyamoto, Akira; Yamaguchi, Masayuki

doi:10.1016/j.polymer.2022.125043

Cited by 4 publications

(8 citation statements)

References 31 publications

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“…For the unmodified PVA, its T m appeared at 192.6°C. The wide peak located at about 134°C was attributed to the absorbed moisture, which made the T m lower than the reference value 35 . T m of PG0, PG10 and PG20 decreased to 161.4°C, 162.8°C and 164.4°C, respectively.…”

Section: Resultsmentioning

confidence: 79%

Polyglycerol‐modified polyvinyl alcohol with improved stability during thermoplastic processing

Zeng

Wang

2023

Polymers for Advanced Techs

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Polyvinyl alcohol (PVA), which can be synthesized via a non-petroleum route, is a multi-hydroxyl polymer with good comprehensive properties and environmental friendliness. However, poor thermal processability impedes its development. Herein, polyglycerol (PGL) was firstly adopted to substitute parts of glycerin as one of the plasticizers to prepare modified PVA with greater thermal stability. FTIR spectra revealed the strong hydrogen-bonding interaction between PGL and PVA which would be destroyed during heating, indicating that PGL was suitable for plasticizing PVA. The introduction of PGL weakened the volatilization of plasticizer as T 5% of modified PVA was remarkably improved from 174.7 C to 245.8 C with the addition of 20 wt% PGL. The effects of PGL content on the crystallization behaviors, melting characteristics, dynamic rheological behaviors, and mechanical properties of PVA were investigated. It revealed that the substitution of PGL for glycerin did not influence the final crystalline structure and crystallinity of PVA, but shortened the crystallization time, improved the tensile strength and decreased the melt index owing to the entanglement between PVA and PGL molecules. Dynamic oscillatory rheological measurement showed that the lowest complex viscosity was obtained when 10 wt% PGL was incorporated, which is beneficial for practical processing and film forming.Under proper processing conditions, the production and application of this hot-blown PVA film were realized at an experimental scale. This work sheds light on the exploitation of new plasticizers with high plasticizing efficiency and thermal stability during processing of PVA.blown film, melt processing, plasticizer, polyglycerol, polyvinyl alcohol | INTRODUCTION"White pollution" has drawn people's attention over the last few decades as plenty of petroleum-based non-degradable plastics are disposed of improperly. 1,2 In consideration of the pollution hazard brought by traditional plastic packaging, many environmental-friendly materials have been developed to be alternatives, such as polylactic acid (PLA), poly(propylene carbonate) (PPC), poly(butylene adipate-coterephthalate) (PBAT), poly(butylene succinate) (PBS), and polyvinyl alcohol (PVA). 3-5 Among these polymers, multi-hydroxyl PVA catches the spotlights since it possesses excellent mechanical property and prominent film-forming ability. 6,7 PVA, whose molecular chains only compose of C, H, and O elements, has no toxicity, admirable compatibility with biomass, resistance to oils and chemicals, good gas barrier property, antistatic property, high transparency and printability. 8,9 The water solubility of PVA is reliant upon its degree of hydrolysis and molecular weight, while its aqueous solutions present a pH value of 7, which would not

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Section: Resultsmentioning

confidence: 79%

Polyglycerol‐modified polyvinyl alcohol with improved stability during thermoplastic processing

Zeng

Wang

2023

Polymers for Advanced Techs

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“…For the annealed samples, the tensile data were not denoted in the table because the experimental data have a large experimental error, presumably owing to the warpage of specimens. Considering that PVAL shows a high modulus, the modulus increase by the PVAL addition may be attributed to the high modulus of PVAL dispersions. A similar phenomenon has also been detected in blends with polypropylene. , Moreover, the annealing procedure increased the modulus and strength of all the samples.…”

Section: Resultsmentioning

confidence: 99%

“…Considering that PVAL shows a high modulus, the modulus increase by the PVAL addition may be attributed to the high modulus of PVAL dispersions. A similar phenomenon has also been detected in blends with polypropylene. , Moreover, the annealing procedure increased the modulus and strength of all the samples. Although the annealing procedure enhances the toughness of PLA, which is attributed to the conformation change, , the present results must be attributed to the increase in the PLA crystallinity.…”

Section: Resultsmentioning

confidence: 99%

“…The modulus increase, i.e., high rigidity, is significantly required especially for automobile parts to reduce the weight recently. Therefore, this technique should be focused because the modulus was higher than that of a conventional material composed of polypropylene. ,, …”

Section: Resultsmentioning

confidence: 99%

“…Therefore, this technique should be focused because the modulus was higher than that of a conventional material composed of polypropylene. 18,22,39 Figure 6 shows the picture of the injection-molded PLA/ PVAL (90/10) test pieces that have been annealed at various temperatures for 3 h. The picture was taken after cooling at room temperature for 1 day. The sample lengths in the MD before/after annealing were measured, and the ratios were calculated, as denoted in the figure . Annealing below the T g did not affect the length as expected.…”

Section: Shrinkage Of the Injection-molded Samplesmentioning

confidence: 99%

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Anomalous Postprocessing Dimensional Change of Injection-Molded Products Composed of Poly(lactic acid) and Poly(vinyl alcohol)

Yamaguchi

Wen

Kimura

et al. 2023

ACS Appl. Polym. Mater.

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The present study revealed that an injection-molded product comprising poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVAL) exhibited an anomalous dimensional change, i.e., expansion in the flow direction, after postprocessing annealing (around 2.9% expansion by annealing at 80−100 °C for 3 h). Although the crystallization of the PLA during cooling was not accelerated by the addition of PVAL, the PLA showed transcrystallization from the dispersed PVAL droplets, which were deformed in the flow direction, during postprocessing annealing. Therefore, after annealing, the injection-molded products exhibited a high degree of molecular orientation, in contrast to the original unannealed products, which were not oriented. This anomalous behavior should be noted as a means of controlling dimensional change after processing.

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Growth of molecular orientation during post‐process annealing of poly(lactic acid) containing a fibrous nucleating agent

Vo,

Yamaguchi

2024

J of Applied Polymer Sci

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Poly(lactic acid) (PLA) is known to exhibit slow crystallization. Therefore, post‐process annealing is often performed, at which structure change is inevitable. In this paper, the structure development during annealing of PLA containing N,N′‐ethylenebis(12‐hydroxystearamide) (EBHS) is studied using extruded strands. First, EBHS, which acts as a nucleating agent, is dissolved in molten PLA, and then segregates with a fibrous shape during cooling. Next, the PLA containing EBHS is extruded, which causes EBHS fibers in the strand to orientate with the flow direction. When the strand is annealed at 100°C, amorphous PLA chains initially lose their orientation. Then, the chain orientation in the PLA strand develops because of transcrystallization from the surface of EBHS fibers that are aligned with the flow direction. As a result, the Hermans orientation function increases from 1.8 × 10−3 (before annealing) to 6.0 × 10−3 (after annealing). Moreover, the annealed PLA/EBHS strand shows less shrinkage (0.80 ± 0.19%) than the annealed PLA strand (2.04 ± 0.27%). The promotion of PLA chain orientation induced by the presence of aligned EBHS fibers can be used to control the structure and dimensional change of PLA products during annealing.

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Crystallinity enhancement of extruded polypropylene containing poly(vinyl alcohol) fibers prepared in situ

Cited by 4 publications

References 31 publications

Polyglycerol‐modified polyvinyl alcohol with improved stability during thermoplastic processing

Polyglycerol‐modified polyvinyl alcohol with improved stability during thermoplastic processing

Anomalous Postprocessing Dimensional Change of Injection-Molded Products Composed of Poly(lactic acid) and Poly(vinyl alcohol)

Growth of molecular orientation during post‐process annealing of poly(lactic acid) containing a fibrous nucleating agent

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