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On the effects of hydroxyl substitution degree and molecular weight on mechanical and water barrier properties of hydroxypropyl methylcellulose films
Carbohydrate Polymers ( IF 10.7 ) Pub Date : 2018-01-06 , DOI: 10.1016/j.carbpol.2018.01.016
Caio G. Otoni , Marcos V. Lorevice , Márcia R. de Moura , Luiz H.C. Mattoso

In line with the increasing demand for sustainable packaging materials, this contribution aimed to investigate the film-forming properties of hydroxypropyl methylcellulose (HPMC) to correlate its chemical structure with film properties. The roles played by substitution degree (SD) and molecular weight (Mw) on the mechanical and water barrier properties of HPMC films were elucidated. Rheological, thermal, and structural experiments supported such correlations. SD was shown to markedly affect film affinity and barrier to moisture, glass transition, resistance, and extensibility, as hydroxyl substitution lessens the occurrence of polar groups. Mw affected mostly the rheological and mechanical properties of HPMC-based materials. Methocel® E4 M led to films featuring the greatest tensile strength (ca., 67 MPa), stiffness (ca., 1.8 GPa), and extensibility (ca., 17%) and the lowest permeability to water vapor (ca., 0.9 g mm kPa−1 h−1 m−2). These properties, which arise from its longer and less polar chains, are desirable for food packaging materials.



中文翻译:

羟基取代度和分子量对羟丙基甲基纤维素膜力学性能和阻水性能的影响

为了满足对可持续包装材料日益增长的需求,该研究旨在研究羟丙基甲基纤维素(HPMC)的成膜性能,以使其化学结构与薄膜性能相关联。阐明了取代度(SD)和分子量(M w)对HPMC膜的机械和阻水性能的作用。流变学,热学和结构实验均支持这种相关性。由于羟基取代减少了极性基团的产生,因此显示出SD显着影响膜的亲和力和对水分,玻璃化转变,电阻和延展性的屏障。M w主要影响基于HPMC的材料的流变和机械性能。甲基纤维素®E4 M导致薄膜具有最大的拉伸强度(67 MPa),刚度(1.8 GPa),延展性(17%)和最低的水蒸气渗透性(0.9 g mm) kPa -1  h -1  m -2)。这些特性是由于其较长和较少的极性链而产生的,是食品包装材料所需要的。

更新日期:2018-01-06
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