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首页> 外文期刊>Macromolecular symposia >Effects of Size and Specific Surface Area of Boron Nitride Particles on the Crystallization of Bacterial Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
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Effects of Size and Specific Surface Area of Boron Nitride Particles on the Crystallization of Bacterial Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

机译：氮化硼颗粒的大小和比表面积对细菌聚3-羟基丁酸酯-co-3-羟基戊酸酯的结晶的影响

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摘要

Three different grades of Boron Nitride (BN) powder (BN NX1, BN NX5 and BN HCV) having different mean particle size (0.7 to 11 mm) and specific surface area (16 to 40 m~2? g~(-1)) were used as nucleating agents for poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) at a fixed concentration of 2 wt %. Polarized Optical Microscopy (POM) observations, coupled to Differential Scanning Calorimetric (DSC) measurements, allowed to monitor both the isothermal and non-isothermal crystallization of neat and nucleated PHBVs. It was found that the addition of BN to PHBV modifies the mechanisms of crystallization by starting it at lower supercooling degrees and reducing the half-crystallization time. This work proved that DSC can replace POM whenever POM does not allow to estimate directly the average linear growth rate of the spherulites during crystallization. The Hoffman-Lauritzen theory was used to explain the effects of the addition of different grades of BN on PHBV crystallization. As a result, a transition from growth regime III to the growth regime II could be observed for nucleated PHBVs, no matter the grade of BN added. It was evidenced that the coupling between the amorphous and the crystalline phase is modified by the presence of the BN particles. In particular, for a given concentration of nucleating agent, it is the mean size and the specific surface area of BN particles that affect PHBV crystallization.
机译：三种不同等级的氮化硼（BN）粉末（BN NX1，BN NX5和BN HCV）具有不同的平均粒径（0.7至11 mm）和比表面积（16至40 m〜2？g〜（-1））将其用作固定浓度为2重量％的聚（3-羟基丁酸酯-co-3-羟基戊酸酯）（PHBV）的成核剂。偏振光学显微镜（POM）观察与差示扫描量热法（DSC）测量相结合，可以监测纯净和有核PHBV的等温和非等温结晶。发现在PHBV中添加BN可以通过在较低的过冷度下开始结晶并减少半结晶时间来改变其结晶机理。这项工作证明，只要POM不允许直接估计结晶过程中球晶的平均线性增长率，DSC就可以代替POM。 Hoffman-Lauritzen理论用于解释添加不同等级的BN对PHBV结晶的影响。结果，无论添加的BN等级如何，对于有核PHBV都可以观察到从生长方案III到生长方案II的转变。已经证明，BN颗粒的存在改变了非晶相和结晶相之间的偶联。特别是，对于给定浓度的成核剂，影响PHBV结晶的是BN颗粒的平均尺寸和比表面积。

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