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Article ; Online: Role of Shear Flow on Structure Development during Post-Processing Annealing for Poly(lactic acid).

Vo, Hoang-Giang Dai / Kida, Takumitsu / Yamaguchi, Masayuki

2023 Volume 15, Issue 3

Abstract: The effect of shear history on structure development during post-processing annealing was studied using poly(lactic acid) PLA. Since PLA shows a low crystallization rate, quenched films had no crystallinity. Moreover, molecular orientation was not ... ...

Abstract	The effect of shear history on structure development during post-processing annealing was studied using poly(lactic acid) PLA. Since PLA shows a low crystallization rate, quenched films had no crystallinity. Moreover, molecular orientation was not detected in the films. During the annealing procedure beyond its glass transition temperature, however, molecular orientation to the flow direction occurred with the crystallization growth in the films having an appropriate shear history. This peculiar crystal growth during the annealing was most probably attributed to the crystallization from extended chain crystals generated during the applied shear history, although the amount of extended chain crystals was low. The results obtained in this study should be noted because the molecular orientation proceeded due to the annealing history applied. Furthermore, this phenomenon will be used to suppress dimensional change and increase product rigidity.
Language	English
Publishing date	2023-01-30
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2527146-5
ISSN	2073-4360 ; 2073-4360
ISSN (online)	2073-4360
ISSN	2073-4360
DOI	10.3390/polym15030693
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Novel Transparent Films Composed of Bisphenol-A Polycarbonate and Copolyester.

Hasegawa, Hiroyuki / Kida, Takumitsu / Yamaguchi, Masayuki

Polymers

2022 Volume 14, Issue 19

Abstract: In this paper, the structure and properties of transparent films composed of bisphenol-A polycarbonate (PC) and a commercially available copolyester, poly(1,4-cyclohexanedimethanol- ...

Abstract	In this paper, the structure and properties of transparent films composed of bisphenol-A polycarbonate (PC) and a commercially available copolyester, poly(1,4-cyclohexanedimethanol-
Language	English
Publishing date	2022-10-03
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2527146-5
ISSN	2073-4360 ; 2073-4360
ISSN (online)	2073-4360
ISSN	2073-4360
DOI	10.3390/polym14194146
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Viscoelastic Properties of Fully Biomass-Based Transparent Plastic Comprising Cellulose Acetate and Citrate Ester.

Kimura, Takeyoshi / Kida, Takumitsu / Yamaguchi, Masayuki

Materials (Basel, Switzerland)

2022 Volume 15, Issue 9

Abstract: Viscoelastic properties including melt processability were evaluated for a fully biomass-based glassy plastic comprising cellulose acetate (CA) and triethyl citrate (TEC). The TEC exerted an excellent plasticizing effect without dissolving the CA ... ...

Abstract	Viscoelastic properties including melt processability were evaluated for a fully biomass-based glassy plastic comprising cellulose acetate (CA) and triethyl citrate (TEC). The TEC exerted an excellent plasticizing effect without dissolving the CA crystals. Pure CA has poor melt processability. In contrast, the TEC-plasticized CA had good melt-processability at 205 °C, which is lower than the degradation temperature of CA. Extrusion was possible even at 1000 s
Language	English
Publishing date	2022-04-22
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2487261-1
ISSN	1996-1944
ISSN	1996-1944
DOI	10.3390/ma15093038
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Improvement in Processability for Injection Molding of Bisphenol-A Polycarbonate by Addition of Low-Density Polyethylene.

Kuroda, Yuki / Suzuki, Ken-Ichi / Kikuchi, Genzo / Moonprasith, Nantina / Kida, Takumitsu / Yamaguchi, Masayuki

Materials (Basel, Switzerland)

2023 Volume 16, Issue 2

Abstract: The rheological properties and processability at injection molding were studied for bisphenol-A polycarbonate (PC) that was modified by low-density polyethylene (LDPE) having a low shear viscosity. The LDPE addition significantly decreased the steady- ... ...

Abstract	The rheological properties and processability at injection molding were studied for bisphenol-A polycarbonate (PC) that was modified by low-density polyethylene (LDPE) having a low shear viscosity. The LDPE addition significantly decreased the steady-state shear viscosity, especially in the high shear rate region. The decrease did not originate from slippage on the die wall but due to interfacial slippage between the PC and dispersed LDPE droplets that deformed to the flow direction to a great extent. As a result of the viscosity decrease, injection pressure largely decreased from 150 to 110 MPa with the addition only 5 wt.% of LDPE. The enhanced flowability also reduced the warpage of the molded product significantly, demonstrating that the processability at injection molding was improved by the addition of LDPE.
Language	English
Publishing date	2023-01-16
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2487261-1
ISSN	1996-1944
ISSN	1996-1944
DOI	10.3390/ma16020866
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Enhancing the Mechanical Properties of Poly(vinyl alcohol) Fibers by Lithium Iodide Addition.

Taoka, Yusuke / Asmaa Saari, Riza / Kida, Takumitsu / Yamaguchi, Masayuki / Matsumura, Kazuaki

ACS omega

2023 Volume 8, Issue 36, Page(s) 32623–32634

Abstract: The effect of lithium iodide (LiI) on the mechanical strength, properties, and molecular orientation of poly(vinyl alcohol) (PVA) fibers spun by wet spinning and then heat-stretched was studied. The stretchability of LiI-PVA fibers was improved, and the ... ...

Abstract	The effect of lithium iodide (LiI) on the mechanical strength, properties, and molecular orientation of poly(vinyl alcohol) (PVA) fibers spun by wet spinning and then heat-stretched was studied. The stretchability of LiI-PVA fibers was improved, and the rupture during stretching was suppressed compared to PVA fibers. In addition, the tensile strength and elastic modulus of the thermally stretched fibers have been significantly improved. It was also found that the addition of LiI improves the molecular orientation of PVA. This was achieved because LiI reduced the hydrogen bonds between the molecular chains of PVA, resulting in reduced crystallinity. Most of the LiI in the fiber could be removed by a coagulation bath and washing during the spinning process. This means that LiI is eventually removed, and the heat-treatment strengthens the hydrogen bonds, resulting in excellent mechanical strength.
Language	English
Publishing date	2023-08-31
Publishing country	United States
Document type	Journal Article
ISSN	2470-1343
ISSN (online)	2470-1343
DOI	10.1021/acsomega.3c03280
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Microstructural Interpretation of Influences of Molecular Weight on the Tensile Properties of High-Density Polyethylene Solids Using Rheo-Raman Spectroscopy

Kida, Takumitsu / Hiejima, Yusuke / Nitta, Koh-hei

Macromolecules. 2020 Dec. 16, v. 54, no. 1

2020

Abstract: The influence of the weight-average molecular weight (Mw) on the structure–properties relationship was investigated by preparing high-density polyethylenes (HDPEs) of various Mw but constant polydispersity index (Mw/Mₙ) values. The thickness of the ... ...

Abstract	The influence of the weight-average molecular weight (Mw) on the structure–properties relationship was investigated by preparing high-density polyethylenes (HDPEs) of various Mw but constant polydispersity index (Mw/Mₙ) values. The thickness of the lamellar crystalline layer increased with increasing Mw, whereas the amorphous characteristics, such as the amorphous layer thickness and tie-molecule fraction, remained unchanged. The microscopic deformation of these HDPEs was investigated by in situ Raman spectroscopy. The orientation parameter ⟨P₂⟩ showed a power law to Mw with an exponent of −3/4 in the strain-hardening region. The Mw dependence of the molecular orientation was interpreted as the realignment of the lamellar cluster units, the size of which was determined by the end-to-end distance of the polymer chains in their melt state. It was found that higher stretching stress is applied to the crystalline chains for HDPEs of lower Mw, implying that a larger amount of taut-tie chains is formed.
Keywords	Raman spectroscopy ; deformation ; molecular weight ; polyethylene
Language	English
Dates of publication	2020-1216
Size	p. 225-234.
Publishing place	American Chemical Society
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	1491942-4
ISSN	1520-5835 ; 0024-9297
ISSN (online)	1520-5835
ISSN	0024-9297
DOI	10.1021/acs.macromol.0c02124
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Impact of Magnesium Salt on the Mechanical and Thermal Properties of Poly(vinyl alcohol).

Saari, Riza Asmaa / Nasri, Muhammad Shahrulnizam / Kida, Takumitsu / Yamaguchi, Masayuki

Polymers

2021 Volume 13, Issue 21

Abstract: The effects of magnesium salts with various anion species on the structure and properties of a poly(vinyl alcohol) (PVA) film were studied. The glass transition temperature of the PVA film increased following the addition of a magnesium salt. Furthermore, ...

Abstract	The effects of magnesium salts with various anion species on the structure and properties of a poly(vinyl alcohol) (PVA) film were studied. The glass transition temperature of the PVA film increased following the addition of a magnesium salt. Furthermore, the salt greatly enhanced the modulus and yield stress and reduced the crystallinity of the film. These effects were attributed to the strong ion-dipole interactions between the magnesium salts and the PVA chains. The strength of interaction, i.e., the reduction of segmental motions, depended on the anion species in the following order: Mg(ClO
Language	English
Publishing date	2021-10-30
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2527146-5
ISSN	2073-4360 ; 2073-4360
ISSN (online)	2073-4360
ISSN	2073-4360
DOI	10.3390/polym13213760
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Anomalous Strain Recovery after Stress Removal of Graded Rubber.

Do, Quoc-Viet / Kida, Takumitsu / Yamaguchi, Masayuki / Washizu, Kensuke / Nagase, Takayuki / Tada, Toshio

Polymers

2022 Volume 14, Issue 24

Abstract: Mechanical responses after the uniaxial deformation of graded styrene-butadiene rubber (SBR) with a gradient in the crosslink points in the thickness direction were investigated as compared with those of homogenously vulcanized SBR samples. The ... ...

Abstract	Mechanical responses after the uniaxial deformation of graded styrene-butadiene rubber (SBR) with a gradient in the crosslink points in the thickness direction were investigated as compared with those of homogenously vulcanized SBR samples. The elongational residual strain of a graded sample was found to depend on the part with a high crosslink density. Therefore, it showed good rubber elasticity. After stress removal, moreover, the graded sample showed a marked warpage. This suggested that shrinking stress acted on the surface with a high crosslink density, which would avoid a crack growth on the surface. The sample shape was then recovered to be flat very slowly, indicating that the shrinking stress worked for a long time. This unique rubber elasticity, i.e., slow strain recovery with an excellent strain recovery, makes graded rubber highly significant.
Language	English
Publishing date	2022-12-14
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2527146-5
ISSN	2073-4360 ; 2073-4360
ISSN (online)	2073-4360
ISSN	2073-4360
DOI	10.3390/polym14245477
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Segregation Behavior of Miscible PC/PMMA Blends during Injection Molding.

Moonprasith, Nantina / Date, Jitsuhiro / Sako, Takumi / Kida, Takumitsu / Hiraoka, Tatsuhiro / Yamaguchi, Masayuki

Materials (Basel, Switzerland)

2022 Volume 15, Issue 9

Abstract: Miscible blends composed of bisphenol-A polycarbonate (PC) and poly(methyl methacrylate) (PMMA), in which one of them has low molecular weight, were employed to study the surface segregation behavior during flow. The blend samples showed typical ... ...

Abstract	Miscible blends composed of bisphenol-A polycarbonate (PC) and poly(methyl methacrylate) (PMMA), in which one of them has low molecular weight, were employed to study the surface segregation behavior during flow. The blend samples showed typical rheological behaviors, such as simple polymer melts without a long-time relaxation mechanism ascribed to phase separation, demonstrating that they were miscible. After injection molding, the amounts of a low molecular weight component on the blend surface were found to be larger than the actual blend ratio. Because the injection-molded products were transparent despite a huge difference in refractive indices between PC and PMMA, they showed no phase separation. This result demonstrated that surface segregation of a low molecular weight component occurred under flow field, which expands the material design such as tough plastics with good scratch resistance and optical fibers with tapered refractive index.
Language	English
Publishing date	2022-04-20
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2487261-1
ISSN	1996-1944
ISSN	1996-1944
DOI	10.3390/ma15092994
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Incorporation of Boronic Acid Functionality into Isotactic Polypropylene and Its Application as a Cross-Linking Point

Tanaka, Ryo / Fujii, Hiroya / Kida, Takumitsu / Nakayama, Yuushou / Shiono, Takeshi

Macromolecules. 2021 Jan. 29, v. 54, no. 3

2021

Abstract: Direct copolymerization of propylene and functional monomers using early transition metal catalysts is a prominent synthesis method to render a functionality to polypropylene maintaining high stereoregularity. In this study, we investigated the ... ...

Abstract	Direct copolymerization of propylene and functional monomers using early transition metal catalysts is a prominent synthesis method to render a functionality to polypropylene maintaining high stereoregularity. In this study, we investigated the copolymerization of propylene and alkenylboronic acid moieties using the Zr complex and found that diaminonaphthalene (dan) is a good protective group for the boronic acid. Dan-protected boronic acid scarcely reduced the stereospecificity of the propylene polymerization so that the incorporation of 3.8 mol % comonomer still maintained a high melting point (107 °C). Moreover, deprotection of boronic acid amide proceeded along with the standard purification of polypropylene in acidic methanol. Boronic acid-functionalized isotactic polypropylene showed high Young’s modulus and strength probably because the copolymer was cross-linked upon molding via dehydrotrimerization of the boronic acids. Such cross-link was accelerated by the addition of a secondary amine.
Keywords	boronic acids ; composite polymers ; copolymerization ; crosslinking ; methanol ; polypropylenes ; propylene ; secondary amines ; stereospecificity
Language	English
Dates of publication	2021-0129
Size	p. 1267-1272.
Publishing place	American Chemical Society
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	1491942-4
ISSN	1520-5835 ; 0024-9297
ISSN (online)	1520-5835
ISSN	0024-9297
DOI	10.1021/acs.macromol.0c02686
Database	NAL-Catalogue (AGRICOLA)

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