Facile design of heat-triggered shape memory ethylene-vinyl acetate copolymer/nitrile-butadiene thermoplastic vulcanizates via zinc dimethacrylate induced interfacial compatibilization

2019 ◽  
Vol 76 ◽  
pp. 481-489 ◽  
Author(s):  
Libin Wang ◽  
Jing Hua ◽  
Zhaobo Wang
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Thermoplastic Vulcanizates ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

A novel heat-triggered shape-memory polymer based on ethylene–vinyl acetate copolymer/nitrile–butadiene rubber thermoplastic vulcanizates

2019 ◽  
Vol 33 (9) ◽  
pp. 1217-1233 ◽  
Author(s):  
Libin Wang ◽  
Kesi Xiong ◽  
Zhaobo Wang
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Shape Memory Polymer ◽  
Weight Ratio ◽  
Ethylene Vinyl Acetate ◽  
Butadiene Rubber ◽  
Nitrile Butadiene Rubber ◽  
Thermoplastic Vulcanizates ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

Achieving considerable shape-memory effects is a challenge for typical sea-island structured polymer blends. In this article, we successfully fabricated a novel heat-triggered shape-memory polymer (HSMP) based on ethylene–vinyl acetate copolymer/nitrile–butadiene rubber (EVA/NBR) thermoplastic vulcanizates (TPVs) via dynamic vulcanization. The influence of deformation temperature ( Td), recovery temperature ( Tr), and recovery time on the shape-memory behavior of the EVA/NBR (weight ratio = 80/20) TPV was investigated systematically. The shape-memory result of the EVA/NBR (weight ratio = 80/20) TPV demonstrated that when the Td was close to the melting temperature ( Tm) of the EVA phase (76°C), the TPV could obtain a good shape fixity ratio (>95%) and an excellent shape recovery ratio (>95%) at 100% stretch ratio. A shape-memory mechanism was proposed for this HSMP. The dynamic mechanical analysis results under temperature sweep mode showed that with increasing EVA content in TPVs, the tan δ decreased, while the storage modulus increased. The morphology observation showed that the cross-linked NBR particles were dispersed evenly in the etched surface of EVA/NBR TPV with an average diameter of approximately 2–6 μm. The longitudinal stretching surface of the EVA/NBR TPV exhibited the banding-like texture microstructure during the stretching process.

scholarly journals Design of Ethylene-Vinyl Acetate Copolymer Fiber with Two-Way Shape Memory Effect

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1599 ◽  
Author(s):  
Xiaoming Qi ◽  
Wentong Yang ◽  
Laiming Yu ◽  
Wenjun Wang ◽  
Haohao Lu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Crosslink Density ◽  
Melt Spinning ◽  
Uv Curing ◽  
Ethylene Vinyl Acetate ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties, and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC, and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 261.86 ± 13.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators, and artificial muscles.

scholarly journals Effect of Mixing Method on Properties of Ethylene Vinyl Acetate Copolymer/Natural Rubber Thermoplastic Vulcanizates

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1739 ◽  
Author(s):  
Nappaphan Kunanusont ◽  
Chavakorn Samthong ◽  
Fan Bowen ◽  
Masayuki Yamaguchi ◽  
Anongnat Somwangthanaroj
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Rheological Properties ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Dynamic Vulcanization ◽  
Thermoplastic Vulcanizates ◽  
Mixing Method ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

Thermoplastic vulcanizate (TPV) has excellent elastomeric properties and can be reprocessed multiple times. TPV is typically produced by using the dynamic vulcanization (DV) method in which rubber is crosslinked simultaneously with thermoplastics. Peroxide-crosslinked TPV can increase the compatibility between rubber and thermoplastics but loses its reprocessability due to excess crosslinking in the latter. In this work, we overcome this obstacle by using a two-step mixing method to prepare fully crosslinked elastomers of ethylene vinyl acetate copolymer (EVA) and natural rubber (NR). Each sample formulation was prepared with three different mixing methods for comparison: NR-DV, Split-DV, and All-DV. For NR-DV, NR was crosslinked prior to the addition of EVA together with the thermal stabilizer (TS). For Split-DV, a small amount of EVA and NR was crosslinked prior to the addition of EVA and TS. In the All-DV method, EVA and NR were crosslinked, and then TS was added. The appearance and processability of the samples were affected by the degree of crosslinking. NR-DV showed a non-homogeneous texture. Although the samples of the All-DV method appeared homogeneous, their mechanical and rheological properties were inferior to those of the Split-DV method. The mechanical properties of the Split-DV samples were not significantly changed after reprocessing 10 times. Therefore, Split-DV is the preferred method for TPV production.

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