Melendez-Rodriguez Beatriz, Torres-Giner Sergio, Zavagna Lorenzo, Sammon Chris, Cabedo Luis, Prieto Cristina, Lagaron Jose M
Novel Materials and Nanotechnology Group, Institute of Agrochemistry and Food Technology (IATA), Spanish Council for Scientific Research (CSIC), Calle Catedrático Agustín Escardino Benllonch 7, 46980 Valencia, Spain.
Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB, UK.
Polymers (Basel). 2021 Jun 23;13(13):2061. doi: 10.3390/polym13132061.
In the present study, poly(ethylene--vinyl alcohol) with 44 mol % ethylene content (EVOH) was managed to be processed, for the first time, by electrospinning assisted by the coaxial technology of solvent jacket. In addition to this, different suspensions of cellulose nanocrystals (CNCs), with contents ranging from 0.1 to 1.0 wt %, were also electrospun to obtain hybrid bio-/non-bio nanocomposites. The resultant fiber mats were thereafter optimally annealed to promote interfiber coalescence at 145 °C, below the EVOH melting point, leading to continuous transparent fiber-based films. The morphological analysis revealed the successful distribution of CNCs into EVOH up to contents of 0.5 wt %. The incorporation of CNCs into the ethylene-vinyl alcohol copolymer caused a decrease in the crystallization and melting temperatures (T and T) of about 12 and 7 °C, respectively, and also crystallinity. However, the incorporation of CNCs led to enhanced thermal stability of the copolymer matrix for a nanofiller content of 1.0 wt %. Furthermore, the incorporation of 0.1 and 0.5 wt % CNCs produced increases in the tensile modulus (E) of ca. 38% and 28%, respectively, but also yielded a reduction in the elongation at break and toughness. The oxygen barrier of the hybrid nanocomposite fiber-based films decreased with increasing the CNCs content, but they were seen to remain high barrier, especially in the low relative humidity (RH) regime, i.e., at 20% RH, showing permeability values lower than 0.6 × 10 m·m·m·Pa·s. In general terms, an optimal balance in physical properties was found for the hybrid copolymer composite with a CNC loading of 0.1 wt %. On the overall, the present study demonstrates the potential of annealed electrospun fiber-based high-barrier polymers, with or without CNCs, to develop novel barrier interlayers to be used as food packaging constituents.
在本研究中，首次通过溶剂夹套同轴技术辅助的静电纺丝工艺，成功加工了乙烯含量为44摩尔%的聚（乙烯-乙烯醇）（EVOH）。除此之外，还对含量范围为0.1至1.0 wt%的不同纤维素纳米晶体（CNC）悬浮液进行了静电纺丝，以获得杂化生物/非生物纳米复合材料。随后，将所得纤维毡在低于EVOH熔点的145°C下进行最佳退火处理，以促进纤维间的聚结，从而得到连续透明的纤维基薄膜。形态分析表明，CNC在高达0.5 wt%的含量下成功地分散在EVOH中。将CNC掺入乙烯-乙烯醇共聚物中，分别使结晶温度和熔融温度（T 和 T）降低了约12°C和7°C，同时也降低了结晶度。然而，对于1.0 wt%的纳米填料含量，CNC的掺入提高了共聚物基体的热稳定性。此外，掺入0.1 wt%和0.5 wt%的CNC分别使拉伸模量（E）提高了约38%和28%，但同时也导致了断裂伸长率和韧性的降低。杂化纳米复合纤维基薄膜的氧气阻隔性能随着CNC含量的增加而降低，但在低相对湿度（RH）条件下，即20%RH时，它们仍保持高阻隔性能，渗透率值低于0.6×10 m·m·m·Pa·s。总体而言，对于CNC负载量为0.1 wt%的杂化共聚物复合材料，在物理性能方面找到了最佳平衡。总体而言，本研究证明了退火静电纺丝纤维基高阻隔聚合物（含或不含CNC）在开发用作食品包装成分的新型阻隔中间层方面的潜力。
