Faculty of Polymer Engineering, Sahand University of Technology, Sahand New Town, Tabriz 51335-1996, Iran.
Department of Polymer Engineering, University of Tehran, Kish International Campus, Kish Island, Iran.
Int J Biol Macromol. 2024 Nov;279(Pt 3):135345. doi: 10.1016/j.ijbiomac.2024.135345. Epub 2024 Sep 6.
Plasticized PLA plastic films are being increasingly used in, among others, packaging and agriculture sectors in an attempt to address the rapid growth of municipal waste. The present paper aims to review the recent progress and the state-of-the-art in the field of fully bio-renewable tough blends of PLA with green plasticizers aimed at developing flexible packaging films. The different classes of green substances, derived from completely bio-renewable resources, used as potential plasticizers for PLA resins are reviewed. The effectiveness of these additives for PLA plasticization is discussed by describing their effects on different properties of PLA. The performance of these blends is primarily determined by the solvent power, compatibility, efficiency, and permanence of plasticizer present in the PLA matrix of resulting films. The various chemical modification strategies employed to tailor the phase interactions, dispersion level and morphology, plasticization efficiency, and permanence, including functionalization, oligomerization, polymerization and self-crosslinking, grafting and copolymerization, and dynamic vulcanization are demonstrated. Sometimes a third component has also been added to the plasticized binary blends as compatibilizer to further promote dispersion and interfacial adhesion. The impact of chemical structure, size and molecular weight, chemical functionalities, polarity, concentration, topology as well as molecular architectures of the plasticizers on the plasticizer performance and the overall characteristics of resulting plasticized PLA materials is discussed. The morphological features and toughening mechanisms for PLA/plasticizer blends are also presented. The different green liquids employed show varying degree of plasticization. Some are more useful for semi-rigid applications, while some others can be used for very flexible products. There is an optimum level of plasticizer in PLA matrices above which the tensile ductility deteriorates. Esters-derivatives of bio-based plasticizers have been shown to be very promising additives for PLA modification. Some plasticizers impart additional functions such as antioxidation and antibacterial activity to the resulting PLA materials, or compatibilization in PLA-based blends. While the primary objective of plasticization is to boost the processability, flexibility, and toughness over wider practical conditions, the bio-degradability, permeability and long-term stability of microstructure (and thereby properties) of the plasticized films against light, weathering, thermal aging, and oxidation deserve further investigations.
可塑 PLA 塑料薄膜在包装和农业等领域的应用越来越广泛，旨在解决城市垃圾的快速增长问题。本文旨在综述完全生物可再生 PLA 与绿色增塑剂的坚韧共混物领域的最新进展和最新技术，旨在开发柔性包装薄膜。综述了用作 PLA 树脂潜在增塑剂的不同类别绿色物质，这些绿色物质完全源自生物可再生资源。通过描述它们对 PLA 不同性能的影响，讨论了这些添加剂对 PLA 增塑的效果。这些共混物的性能主要取决于存在于所得薄膜 PLA 基质中的增塑剂的溶剂能力、相容性、效率和持久性。为了调整相相互作用、分散水平和形态、增塑效率和持久性，包括功能化、低聚化、聚合和自交联、接枝和共聚以及动态硫化，采用了各种化学改性策略。有时，还将第三种成分添加到增塑的二元共混物中作为增容剂，以进一步促进分散和界面附着力。讨论了增塑剂的化学结构、尺寸和分子量、化学官能团、极性、浓度、拓扑以及增塑剂的分子结构对增塑剂性能和所得增塑 PLA 材料整体特性的影响。还介绍了 PLA/增塑剂共混物的形态特征和增韧机理。所使用的不同绿色液体显示出不同程度的增塑效果。有些更适用于半刚性应用，而有些则可用于非常柔性的产品。在 PLA 基质中存在最佳的增塑剂水平，超过该水平，拉伸延展性会恶化。生物基增塑剂的酯衍生物已被证明是 PLA 改性非常有前途的添加剂。一些增塑剂为所得 PLA 材料赋予了额外的功能，例如抗氧化和抗菌活性，或者在 PLA 基共混物中赋予了增容作用。虽然增塑的主要目的是在更广泛的实际条件下提高加工性、柔韧性和韧性，但生物降解性、渗透性和微结构（从而是性能）的长期稳定性，包括对光、风化、热老化和氧化的抵抗力，值得进一步研究。
