Polymer ( IF 4.6 ) Pub Date : 2018-01-05 , DOI: 10.1016/j.polymer.2018.01.009 Takahiro Danjo , Tadahisa Iwata
Traditionally, cellulose linear acyl esters such as cellulose acetate or cellulose propionate have been used as thermo-plasticized materials from renewable resources for decades. The properties of these kinds of cellulose esters can be varied by changing carbon number (C) of acyl substituents. In this study, a series of cellulose ester derivatives with branched acyl substituents were synthesized by the heterogeneous reaction, and their thermal, mechanical, and structural properties were investigated in comparison with cellulose linear acyl esters. All cellulose branched esters have crystallinity, and tended to show higher melting temperature and glass transition temperature than those of cellulose linear esters with the same C number. Cellulose isobutyrate (branched ester, C = 4) had especially high melting temperature (248 °C) compared with those of cellulose linear esters such as cellulose butyrate (C = 4, 182 °C) and cellulose propionate (C = 3, 235 °C). Colorless and transparent films of cellulose branched esters were fabricated by solvent-casting method. These films showed harder and less flexible properties than those of cellulose linear esters. Structural analyses were conducted by 1D- and 2D-WAXD measurements. Crystal lattice parameters and molecular conformation with 3-fold screw symmetry of cellulose isobutyrate indicated that it has similar crystal structure with cellulose propionate, which could cause high melting temperature and high tensile strength of cellulose isobutyrate. Thus, material properties of cellulose acyl esters can be controlled not only by carbon number of acyl substituents but also by branching structure of acyl groups.
中文翻译:
纤维素支链酯衍生物的合成及其性质和结构分析
传统上,数十年来,纤维素线性酰基酯(例如乙酸纤维素或丙酸纤维素)已被用作可再生资源中的热塑材料。这些纤维素酯的性质可以通过改变酰基取代基的碳数(C)来改变。在这项研究中,通过非均相反应合成了一系列带有支链酰基取代基的纤维素酯衍生物,并与纤维素线性酰基酯进行了比较,研究了它们的热,机械和结构性质。所有纤维素支链酯均具有结晶性,并且倾向于显示出比具有相同C值的纤维素线性酯更高的熔融温度和玻璃化转变温度。异丁酸纤维素(支链酯,与丁酸纤维素(C = 4,182°C)和丙酸纤维素(C = 3,235°C)等纤维素线性酯相比,C = 4)的熔融温度(248°C)特别高。通过溶剂浇铸法制备了无色透明的纤维素支链酯薄膜。这些薄膜显示出比纤维素线性酯更坚硬,柔韧性更差的特性。通过1D和2D-WAXD测量进行结构分析。异丁酸纤维素的晶格参数和具有3倍螺旋对称性的分子构象表明,它与丙酸纤维素具有相似的晶体结构,这可能导致异丁酸纤维素的高熔融温度和高拉伸强度。因此,