Shape memory properties of olefin block copolymer (OBC)/poly(ɛ‐caprolactone) (PCL) blends

Lai, Sun‐Mou; Wang, Xuefen

doi:10.1002/app.45475

Cited by 19 publications

(5 citation statements)

References 33 publications

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“…(1) (2) where ε i is the residual strain in the unloading step after deformation, ε m is a maximum strain applied to the samples, ε p is the strain after recovery of the samples, and n is the number of cycles. The recovery angle of LCE and ELC composites was measured as a function of time to study the effect of Kraft lignin on the recovery time of the specimens.…”

Section: Shape Memory Propertiesmentioning

confidence: 99%

“…Shape memory elastomers (SMEs) are a class of intelligent materials that have been utilized over the past decades in a wide range of applications, such as soft robotics, aerospace engineering, smart actuators and sensors, and biomedical devices [1][2][3][4]. These materials have the ability to deform and memorize their temporary shape and eventually recover to their original shape under applied stress and an external stimulus.…”

Section: Introductionmentioning

confidence: 99%

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Lignin-liquid crystalline elastomeric composites for shape memory applications and their thermomechanical properties

Prathumrat¹,

Nikzad²,

Hajizadeh³

et al. 2023

Express Polym. Lett.

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Liquid crystalline elastomers (LCEs) are stimuli-responsive materials with potential use in shape memory applications. Though particularly suited for shape memory, the LCEs however have some drawbacks such as low shape fixity (R f ) and slow recovery time. To overcome these limitations, new lignin-filled elastomeric liquid crystalline (ELC) composite materials were fabricated. The lignin used is a by-product of Kraft pulping process, which was obtained from renewable resources abundant in nature. Here, we show that the aromatic structure of lignin increases the netpoints density at the microscopic level in the ELC composite systems. Shape memory effects are enhanced by incorporating up to only 7 wt% of lignin, resulting in an R f of 97% for the composites. Concurrently, these composites were able to maintain their shape recovery (R r ) of nearly 100%. The recovery time of the composites reduces with increasing lignin content due to the higher elastic energy released from the netpoints based on the lignin structure. The ELC composites with 7 wt% lignin could fully recover within 70 s, while the neat LCE counterpart took 100 s. Morphological features of dispersed lignin shows that even without surface modification and only a moderate quality of dispersion in LCE matrix, both shape memory and dynamic mechanical properties of the resultant composites can be significantly improved.

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Section: Shape Memory Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lignin-liquid crystalline elastomeric composites for shape memory applications and their thermomechanical properties

Prathumrat¹,

Nikzad²,

Hajizadeh³

et al. 2023

Express Polym. Lett.

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“…Olefin block copolymer (OBC) is a new type of thermoplastic elastomer with a crystallizable ethylene octene block with high melting point (hard segment) and an amorphous ethylene octene block (soft segment) with low glass transition temperature. 16 PA molecules have good compatibility with OBC molecules. When the temperature is higher than the melting temperature of PA, the three-dimensional structure of OBC can inhibit the flow of PA, reduce leakage, and keep the CPCM intact.…”

Section: Introductionmentioning

confidence: 98%

“…Therefore, polymers with good shape memory function have attracted extensive attention. Olefin block copolymer (OBC) is a new type of thermoplastic elastomer with a crystallizable ethylene octene block with high melting point (hard segment) and an amorphous ethylene octene block (soft segment) with low glass transition temperature . PA molecules have good compatibility with OBC molecules.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Performance Analysis of Form-Stable Composite Phase Change Materials with Different EG Particle Sizes and Mass Fractions for Thermal Energy Storage

Chen

et al. 2022

ACS Omega

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The low thermal conductivity and leakage of paraffin (PA) limit its wide application in thermal energy storage. In this study, a series of form-stable composite phase change materials (CPCMs) composed of PA, olefin block copolymer (OBC), and expanded graphite (EG) with different particle sizes (50 mesh, 100 mesh, and 200 mesh) and mass fractions are prepared by melt blending. OBC as a support material could reduce PA leakage during melting, and EG as a thermally conductive filler can improve the thermal performance of PCMs. The microstructure characteristics and chemical and thermal properties of prepared CPCMs are tested and analyzed. The results show that PA/OBC and EG have good compatibility, and there is no chemical reaction with each other to generate new substances. Thermal conductivity can be significantly improved by adding EG, and it is greatly enhanced with the increase in EG particle size at the same EG mass fraction. Simultaneously, the addition of EG increased the melting temperature of CPCMs and decreased the solidification temperature as well; meanwhile, the values of melting temperature and solidification are also reversed for CPCMs compared to PA/OBC. There is an optimal content of EG to balance the thermal conductivity and heat storage capacity for CPCMs. The addition of OBC can provide a stable geometric construction, and the leakage will be further improved with the increase in EG content. Finally, the melting time of CPCMs containing EG-50, EG-100, and EG-200 with 4 wt % EG is shortened by 52.9, 41.1, and 37.5%, respectively, compared with PCMs without EG in the heat storage and release experiments. Also, the CPCMs with EG-50 have better thermal performance compared with the CPCMs of EG-100 and EG-200.

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“…To our best knowledge, very few OBC-based SMPs articles were available in the literature so far. 21,[36][37][38][39][40][41] Herein, this work is the first two-way OBC-based shape memory melt-blends crosslinked with high thermal stable type peroxide, (2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (DHBP), to form flexible networks with high melting temperature. The selection of silicone could provide a high recovery magnitude (R rec ) without the hindrance of high load on the recovery due to the high elasticity of silicone rubber.…”

mentioning

confidence: 99%

Preparation and characterization of two‐way shape memory olefin block copolymer/silicone elastomeric blends

Lai

Chen

2021

J of Applied Polymer Sci

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Very few olefin block copolymer (OBC)-based shape memory polymers (SMPs) studies were reported in the literature so far. This study investigated the preparation of OBC and silicone elastomeric blends (70/30 and 50/50) using a meltblending technique to form the first two-way OBC-based SMPs, to our best knowledge. Two phr of ((2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (DHBP) was used to prepare flexible OBC/silicone D2 (D2 representing 2 phr of DHBP) networks. DHBP not only assisted the curing of OBC and silicone but also increased their compatibility in the blends. Despite the very low crystallinity of the OBC elastomer component, 10.4%, corresponding to only~7% based on total resins in the OBC/silicone D2 70/30 blend, the rare two-way shape memory behavior at such a low crystallinity was still envisaged. Regarding two-way shape memory results at various loads, both entropy-driven and crystallization-driven contributions to the overall actuation magnitude (R act )were at the highest level under 450 kPa, attributing to the highest orientation of molecular networks in the blends. With increasing the applied stress, the R act of OBC/silicone (70/30) sample increased from 4.1% to 23.7% due to the increased strain-induced crystallization effect confirmed by the XRD (X-ray diffraction) evaluation, while the recovery magnitude (R rec ) was maintained at the high level, close to 90%, without the hindrance of high load on the recovery due to high elasticity of silicone rubber. Besides, the crystallization-driven contribution to the overall actuation magnitude was higher for the blends containing the higher amount of crystalline OBC elastomer in the blends. On behalf of silicone with outstanding thermal stability, high elastic behavior, and high hydrophobicity, OBC/silicone SMP blends with versatile properties could meet different applications.

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Shape memory properties of olefin block copolymer (OBC)/poly(ɛ‐caprolactone) (PCL) blends

Cited by 19 publications

References 33 publications

Lignin-liquid crystalline elastomeric composites for shape memory applications and their thermomechanical properties

Lignin-liquid crystalline elastomeric composites for shape memory applications and their thermomechanical properties

Preparation and Performance Analysis of Form-Stable Composite Phase Change Materials with Different EG Particle Sizes and Mass Fractions for Thermal Energy Storage

Preparation and characterization of two‐way shape memory olefin block copolymer/silicone elastomeric blends

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