Heterogeneous nucleation and self-nucleation of poly(p-dioxanone)
Heterogeneous nucleation and self-nucleation of poly(p-dioxanone)
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DOI：
10.1023/a:1004831731756
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发表时间：
2000-10-01
影响因子：
4.5
通讯作者：
Müller, AJ
中科院分区：
文献类型：
--
作者：
Sabino, MA;Ronca, G;Müller, AJ
采用DSC和偏光显微镜（PM）观察了氮化硼（BN）、滑石和羟基磷灰石（HA）对聚对二氧环酮（PPDX）的成核行为变化。DSC研究证明了通常的三个自成核区域的存在，这取决于所采用的自成核温度。到目前为止，PPDX的最佳成核剂是其自身的核，这一结果与所使用的任何其他成核剂的存在与否无关；一旦到达结构域II，自成核主导了成核过程。BN和滑石粉能够使PPDX成核，从而提高其成核密度、熔体冷却后的动态结晶温度（T-c）和结晶焓（δ H-c）。BN是比滑石更好的成核剂。另一方面，HA对PPDX产生“反成核”作用，其特征是成核密度降低，T-c和δ H-c降低。等温结晶的PPDX表现出大带状球晶，其形态随结晶温度的变化而变化，从具有非常明显的马尔氏交叉的单带状结构到双带状球晶。根据生长速率数据的动力学解释，PPDX也显示出随着结晶温度的增加（从状态III到状态II）生长状态的变化。除了PPDX晶体的表面自由能（sigma(e)）略有下降外，BN没有引起任何明显的球晶生长动力学改变（在状态II中）。另一方面，研究发现透明质酸增加了PPDX的球粒生长速率和整体结晶速率，这种增加是由于聚合物在等温结晶过程中经历的降解过程造成的，这种降解过程只存在于含透明质酸的样品中。推测HA表面的磷酸基团与PPDX的酯基之间的相互作用既具有抗核作用，又催化了PPDX的水解降解。(C) 2000 Kluwer学术出版社。
The changes in nucleation behaviour upon addition of Boron Nitride (BN), Talc and Hydroxyapatite (HA) to poly(p-dioxanone) (PPDX) were monitored by DSC and Polarised Optical Microscopy (PM). Self-nucleation DSC studies evidenced the existence of the usual three self-nucleation domains depending on the self-nucleation temperature (T-s) employed. By far the best nucleation agents for PPDX were its own self-nuclei and this result was independent of the presence or absence of any of the other nucleating agents employed; once Domain II was reached, self-nucleation dominated the nucleation process. BN and Talc were able to nucleate PPDX, thereby increasing its nucleation density, its dynamic crystallisation temperature upon cooling from the melt (T-c) and its enthalpy of crystallisation (Delta H-c). BN was a better nucleating agent than talc. HA on the other hand caused an "antinucleation" effect on PPDX characterised by a decrease in its nucleation density, a decrease in its T-c and in Delta H-c. Isothermally crystallised PPDX exhibited large banded spherulites whose morphology changed as a function of crystallisation temperature from single banded structures with a very clear Maltese cross to double banded spherulites. PPDX also shows a change in growth regime upon increasing crystallisation temperature (from Regime III to Regime II) according to the kinetic interpretation of growth rate data. BN did not cause any significant modification of the spherulitic growth kinetics (in Regime II) except for a small decrease in surface free energy of PPDX crystals (sigma(e)). On the other hand HA was found to increase the spherulitic growth rate and the overall crystallisation rate of PPDX, this increase was caused by a degradation process experienced by the polymer during the treatments involved in isothermal crystallisation that was only present in the samples with HA. It is postulated that the interaction between the phosphate groups on the surface of HA and the ester groups of PPDX are responsible for both the antinucleation effect and the catalysis of the hydrolytic degradation of PPDX. (C) 2000 Kluwer Academic Publishers.