Polymers

Research

17 pages, 6410 KiB

Open AccessArticle

Colorless and Transparent Copolyimides and Their Nanocomposites: Thermo-Optical Properties, Morphologies, and Gas Permeabilities

by Hyeon Il Shin, Young-Je Kwark and Jin-Hae Chang

Polymers 2019, 11(4), 585; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11040585 - 01 Apr 2019

Cited by 9 | Viewed by 2754

Abstract

A series of linear aromatic copolyimides (Co-PIs) were synthesized by reacting 4,4′-biphthalic anhydride (BPA) with various molar contents of 2,2′-bis(trifluoromethyl)benzidine (TFB) and p-xylylenediamine (p-XDA) in N,N′-dimethylacetamide (DMAc). Co-PI films were fabricated by solution casting and thermal imidization [...] Read more.

A series of linear aromatic copolyimides (Co-PIs) were synthesized by reacting 4,4′-biphthalic anhydride (BPA) with various molar contents of 2,2′-bis(trifluoromethyl)benzidine (TFB) and p-xylylenediamine (p-XDA) in N,N′-dimethylacetamide (DMAc). Co-PI films were fabricated by solution casting and thermal imidization with poly(amic acid) (PAA) on glass plates. The thermo-optical properties and gas permeabilities of Co-PI films composed of various molar ratios of p-XDA (0.2–1.0 relative to BPA) were investigated. Thermal properties were observed to deteriorate with increasing p-XDA concentration. However, oxygen-transmission rates (O₂TRs) and optical transparencies improved with increasing p-XDA concentration. Co-PI hybrids with a 1:0.2:0.8 molar ratio of BPA:TFB:p-XDA and organically modified hectorite (STN) were prepared by the in situ intercalation method. The morphologies and the thermo-optical and gas permeation properties of the hybrids were examined as functions of STN loading (5–50 wt %). XRD and TEM revealed substantial increases in clay particle agglomeration in the Co-PI hybrid films as the clay loading was increased from 5 to 50 wt %. The coefficient of thermal expansion (CTE) and the O₂TR of a Co-PI hybrid film were observed to improve with increasing STN concentration; however, its optical transparency decreased gradually with increasing STN concentration. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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10 pages, 12641 KiB

Open AccessArticle

Studies on Chemical IR Images of Poly(hydroxybutyrate–co–hydroxyhexanoate)/Poly(ethylene glycol) Blends and Two-Dimensional Correlation Spectroscopy

by Yeonju Park, Sila Jin, Yujeong Park, Soo Min Kim, Isao Noda, Boknam Chae and Young Mee Jung

Polymers 2019, 11(3), 507; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11030507 - 17 Mar 2019

Cited by 11 | Viewed by 3424

Abstract

Biodegradable poly-[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoates] (PHBHx) have been widely studied for their applications in potentially replacing petroleum-based thermoplastics. In this study, the effect of the high molecular weight (Mn = 3400) poly(ethylene glycol) (PEG) blended in the films of PHBHx with different [...] Read more.

Biodegradable poly-[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoates] (PHBHx) have been widely studied for their applications in potentially replacing petroleum-based thermoplastics. In this study, the effect of the high molecular weight (Mn = 3400) poly(ethylene glycol) (PEG) blended in the films of PHBHx with different ratios of PEG was investigated using chemical FTIR imaging. Chemical IR images and FTIR spectra measured with increasing temperature revealed that PEG plays an important role in changing the kinetics of PHBHx crystallization. In addition, two-dimensional correlation spectra clearly showed that thermal properties of PHBHx/PEG blend film changed when the blending ratio of PHBHx/PEG were 60/40 and 50/50. Consequently, PEG leads to changes in the thermal behavior of PHBHx copolymers. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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10 pages, 911 KiB

Open AccessArticle

Preparation and Characterization of Transparent Polyimide–Silica Composite Films Using Polyimide with Carboxylic Acid Groups

by Kwan Ho Moon, Boknam Chae, Ki Seung Kim, Seung Woo Lee and Young Mee Jung

Polymers 2019, 11(3), 489; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11030489 - 13 Mar 2019

Cited by 22 | Viewed by 5576

Abstract

Polyimide (PI) composite films with thicknesses of approximately 100 µm were prepared via a sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMS) with poly(amic acid) (PAA) composite solutions using a thermal imidization process. PAA was synthesized by a conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid [...] Read more.

Polyimide (PI) composite films with thicknesses of approximately 100 µm were prepared via a sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMS) with poly(amic acid) (PAA) composite solutions using a thermal imidization process. PAA was synthesized by a conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid (DABA), which has a carboxylic acid side group, and 2,2′-bis(trifluoromethyl)benzidine (TFMB), with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) in N,N-dimethylacetamide (DMAc). The PAA–silica composite solutions were prepared by mixing PAA with carboxylic acid side groups and various amounts of APTMS in a sol–gel process in DMAc using hydrochloric acid as a catalyst. The obtained PI–silica composite films showed relatively good thermal stability, and the thermal stability increased with increasing APTMS content. The optical properties and in-plane coefficient of thermal expansion (CTE) values of the PI–silica composite films were investigated. The CTE of the PI–silica composite films changed from 52.0 to 42.1 ppm/°C as the initial content of APTMS varied. The haze values and yellowness indices of the composite films increased as a function of the APTMS content. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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9 pages, 4018 KiB

Open AccessArticle

Synergistic Effects of Various Ceramic Fillers on Thermally Conductive Polyimide Composite Films and Their Model Predictions

by Heeseok Song, Byoung Gak Kim, Yong Seok Kim, Youn-Sang Bae, Jooheon Kim and Youngjae Yoo

Polymers 2019, 11(3), 484; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11030484 - 13 Mar 2019

Cited by 23 | Viewed by 4101

Abstract

In this study, thermally conductive composite films were fabricated using an anisotropic boron nitride (BN) and hybrid filler system mixed with spherical aluminum nitride (AlN) or aluminum oxide (Al₂O₃) particles in a polyimide matrix. The hybrid system yielded a [...] Read more.

In this study, thermally conductive composite films were fabricated using an anisotropic boron nitride (BN) and hybrid filler system mixed with spherical aluminum nitride (AlN) or aluminum oxide (Al₂O₃) particles in a polyimide matrix. The hybrid system yielded a decrease in the through-plane thermal conductivity, however an increase in the in-plane thermal conductivity of the BN composite, resulting from the horizontal alignment and anisotropy of BN. The behavior of the in-plane thermal conductivity was theoretically treated using the Lewis–Nielsen and modified Lewis–Nielsen theoretical prediction models. A single-filler system using BN exhibited a relatively good fit with the theoretical model. Moreover, a hybrid system was developed based on two-population approaches, the additive and multiplicative. This development represented the first ever implementation of two different ceramic conducting fillers. The multiplicative-approach model yielded overestimated thermal conductivity values, whereas the additive approach exhibited better agreement for the prediction of the thermal conductivity of a binary-filler system. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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13 pages, 3251 KiB

Open AccessArticle

Enhancement of the Mechanical Properties of Polyimide Film by Microwave Irradiation

by Ju-Young Choi, Seung-Won Jin, Dong-Min Kim, In-Ho Song, Kyeong-Nam Nam, Hyeong-Joo Park and Chan-Moon Chung

Polymers 2019, 11(3), 477; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11030477 - 12 Mar 2019

Cited by 17 | Viewed by 4592

Abstract

Polyimide films have conventionally been prepared by thermal imidization of poly(amic acid)s (PAAs). Here we report that the improvement of tensile strength while increasing (or maintaining) film flexibility of polyimide films was accomplished by simple microwave (MW) irradiation of the PAAs. This improvement [...] Read more.

Polyimide films have conventionally been prepared by thermal imidization of poly(amic acid)s (PAAs). Here we report that the improvement of tensile strength while increasing (or maintaining) film flexibility of polyimide films was accomplished by simple microwave (MW) irradiation of the PAAs. This improvement in mechanical properties can be attributed to the increase in molecular weight of the polyimides by MW irradiation. Our results show that the mechanical properties of polyimide films can be improved by MW irradiation, which is a green approach that requires relatively low MW power, very short irradiation time, and no incorporation of any additional inorganic substance. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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12 pages, 4106 KiB

Open AccessArticle

Studying a Flexible Polyurethane Elastomer with Improved Impact-Resistant Performance

by Jitang Fan and Ang Chen

Polymers 2019, 11(3), 467; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11030467 - 12 Mar 2019

Cited by 34 | Viewed by 5729

Abstract

A flexible polyurethane elastomer (PUE) is studied, and the improved impact-resistant performance is revealed. Compressive stress–strain curves over a wide loading rate range were derived. Under static loading, the rubbery-like characteristics are demonstrated, which are flexible and hyperelastic, to process a large strain [...] Read more.

A flexible polyurethane elastomer (PUE) is studied, and the improved impact-resistant performance is revealed. Compressive stress–strain curves over a wide loading rate range were derived. Under static loading, the rubbery-like characteristics are demonstrated, which are flexible and hyperelastic, to process a large strain of about 60% followed by full recovery upon unloading. Under high-rate loadingcompared with the mechanical data of polyurethane elastomer (PUE) and polyurea (PUA) materials in the literature. Orderly parallel deformation bands were formed from carrying a large strain. The fibrils were found between deformation bands for enhancing the yield/plateau stress. A considerable plastic zone ahead of propagating crack with numerous crazes and microcracks was produced for realizing the dynamic strain energy absorption. This work presents a scientific innovation for developing outstanding impact-resistant polyurethane elastomers for transparent protection engineering. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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17 pages, 3658 KiB

Open AccessEditor’s ChoiceArticle

Anti-Fouling and Anti-Bacterial Modification of Poly(vinylidene fluoride) Membrane by Blending with the Capsaicin-Based Copolymer

by Xiang Shen, Peng Liu, Shubiao Xia, Jianjun Liu, Rui Wang, Hua Zhao, Qiuju Liu, Jiao Xu and Fan Wang

Polymers 2019, 11(2), 323; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11020323 - 13 Feb 2019

Cited by 26 | Viewed by 3938

Abstract

Membrane fouling induced by the adsorption of organic matter, and adhesion and propagation of bacteria onto the surfaces, is the major obstacle for the wide application of membrane technology. In this work, the capsaicin-based copolymer (PMMA-PACMO-Capsaicin) was synthesized via radical copolymerization using methyl [...] Read more.

Membrane fouling induced by the adsorption of organic matter, and adhesion and propagation of bacteria onto the surfaces, is the major obstacle for the wide application of membrane technology. In this work, the capsaicin-based copolymer (PMMA-PACMO-Capsaicin) was synthesized via radical copolymerization using methyl methacrylate (MMA), N-acrylomorpholine (ACMO) and 8-methyl-N-vanillyl-6-nonenamide (capsaicin) as monomers. Subsequently, the capsaicin-based copolymer was readily blended with PVDF to fabricate PVDF/PMMA-PACMO-Capsaicin flat sheet membrane via immersed phase inversion method. The effects of copolymer concentration on the structure and performance of resultant membranes were evaluated systematically. With increase of PMMA-PACMO-Capsaicin copolymer concentration in the casting solution, the sponge-like layer at the membrane cross-section transfers to macroviod, and the pore size and porosity of membranes increase remarkably. The adsorbed bovine serum albumin protein (BSA) amounts to PVDF/PMMA-PACMO-Capsaicin membranes decrease significantly because of the enhanced surface hydrophilicty. During the cycle filtration of pure water and BSA solution, the prepared PVDF/PMMA-PACMO-Capsaicin membranes have a higher flux recovery ratio (FFR) and lower irreversible membrane fouling ratio (R_ir), as compared with pristine PVDF membrane. PVDF/PMMA-PACMO-Capsaicin membrane is found to suppress the growth and propagation of Staphylococcus aureus bacteria, achieving an anti-bacterial efficiency of 88.5%. These results confirm that the anti-fouling and anti-bacterial properties of PVDF membrane are enhanced obviously by blending with the PMMA-PACMO-Capsaicin copolymer. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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15 pages, 3272 KiB

Open AccessEditor’s ChoiceArticle

Surface Modification of Aluminum Nitride to Fabricate Thermally Conductive poly(Butylene Succinate) Nanocomposite

by Zelalem Lule and Jooheon Kim

Polymers 2019, 11(1), 148; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11010148 - 16 Jan 2019

Cited by 51 | Viewed by 5218

Abstract

Biodegradable polymers and their composites are considered promising materials for replacing conventional polymer plastics in various engineering fields. In this study, poly(butylene succinate) (PBS) composites filled with 5% aluminum nitride nanoparticles were successfully fabricated. The aluminum nitride nanoparticles were surface-modified to improve their [...] Read more.

Biodegradable polymers and their composites are considered promising materials for replacing conventional polymer plastics in various engineering fields. In this study, poly(butylene succinate) (PBS) composites filled with 5% aluminum nitride nanoparticles were successfully fabricated. The aluminum nitride nanoparticles were surface-modified to improve their interaction with the PBS matrix. Field-emission scanning electron microscopy revealed that the nanocomposites with surface-modified nanoparticles had better interface interaction and dispersion in the polymer matrix than those with untreated nanoparticles. The PBS/modified AlN nanocomposites exhibited maximal thermal conductivity enhancement, 63.7%, compared to the neat PBS. In addition, other thermomechanical properties of the PBS nanocomposites were investigated in this study. The nanocomposites also showed a superior storage modulus compared to the neat PBS matrix. In this work, a PBS nanocomposite with suitable thermal conductivity that can be used in various electronic fields was fabricated. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

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