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36. Enhanced compatibility and toughness of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/polycaprolactone blends by ring‐opening polymerization and hydrogen bonding of epoxy‐terminated hyperbranched polyester.

Author

Huang, Jiawei, Fang, Yiqi, Zhou, Sudan, Tie, Rui, Zhou, Shuyi, Jin, Yujuan, Tian, Huafeng, and Kumar, Rakesh

Subjects
DYNAMIC mechanical analysis, SIZE reduction of materials, MELT spinning, EXTRUSION process, YOUNG'S modulus
Abstract

Melt extrusion process was followed in order to improve the high crystallinity and poor toughness of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) blend materials. It was achieved by the incorporation of epoxy‐terminated hyperbranched polyester (EHBP) elastomer into PHBV and polycaprolactone (PCL). EHBP cross‐links PHBV and PCL through ring‐opening polymerization of epoxy‐terminated and carboxyl groups. The mass percentages of EHBP in the PHBV/PCL blends are 1, 2, 3, and 4mass%, which are expressed as 1, 2, 3, and 4 phr in the following text. Therefore, when the EHBP content was 3 phr, the Young's modulus and tensile strength of the blends are increased to 750 and 15 MPa, respectively, which was comparable to the biodegradable polymers used for packaging. Simultaneously, compatibility between PHBV and PCL has been improved and the particle size reduction of blends can be obviously observed in scanning electron microscope (SEM) images. Dynamic mechanical analysis (DMA) analysis revealed that PHBV and PCL showed improved compatibility with each other by the addition of EHBP. Differential scanning calorimetry (DSC) revealed that the decrease of crystallinity of the blend was consistent with the increase in mechanical properties. Additionally, all the bio‐blends show good thermal stability. Food overall migration studies showed that the amount of migration of composite materials in contact with food was also far lower than the national standard value. Therefore, PHBV/PCL/EHBP blends are expected to be used in the field of food packaging. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Mechanical and flame-resistance properties of polyurethane-imide foams with different-sized expandable graphite

Author

Xiong, Weiwen, Liu, Hongtao, Tian, Huafeng, Wu, Jiali, Xiang, Aimin, Wang, Chaoyang, Ma, Songbai, and Wu, Qiangxian

Subjects
Polyurethanes -- Mechanical properties -- Analysis, Silanes -- Analysis -- Mechanical properties, Graphite -- Analysis -- Mechanical properties, Engineering and manufacturing industries, Science and technology
Abstract

Polyurethane-imide (PUI) composite foams with expandable graphite (EG) of different sizes were prepared by a polyimide prepolymer method. EG particles were treated with a silane coupling agent to improve compatibility with the foam. The effect of EG particle size on cell morphology, thermal degradation, flame-resistance and mechanical properties of PUI foams was investigated. Results showed that the mean cellular diameter of foams with EG particle was much higher than that of foams with surface-modified EG particle at the same filler loading. When filler particle diameter increased from 20 to 90 pm, the compressive strength, density and closed-cell ratio of foams increased, and then decreased when filler particle diameter further increased from 90 to 150 pm. Thermal stability of foams increased with the increasing filler particle diameter from 20 to 50 [micro]m, and decreased with the increasing filler particle diameter from 50 to 90 [micro]m. The limited oxygen index (LOI) value of foams with surface-modified EG increased from 24.8% to 32.1% when EG particle diameter was below 90 [micro]m. Foams with surface-modified EG exhibited enhanced mechanical properties, thermal stability and flame resistance than foams with neat EG at the same loading. KEYWORDS expandable graphite, particle size, polyurethane-imide foams, surface modification, 1 | INTRODUCTION Polymeric foams possess outstanding thermal insulation performance, low density, excellent mechanical properties, etc, which leads to wide applications in our daily lives. [1-3] Developing high performance polymeric [...]

Published
2020
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