Department of Chemical Engineering, Polymer and Composite Engineering (PaCE) Group, Imperial College London, London SW7 2AZ, UK.
Acta Biomater. 2010 Mar;6(3):756-62. doi: 10.1016/j.actbio.2009.08.020. Epub 2009 Aug 14.
Bioactive, biodegradable composites are increasingly being explored as bone replacement materials and as scaffolds for tissue engineering. Their properties are not only dependent on the properties of the filler and matrix, but are also determined by their interaction. This study investigated the effect on poly(D,L-lactide) (PDLLA) matrix when processed at high-temperatures in the presence of Bioglass particulate filler. Composites with different filler contents were compounded at elevated temperatures by co-extrusion followed by compression moulding and compared with composites of similar composition prepared by thermally induced phase separation (TIPS), a low-temperature processing route. It was found that the inclusion of Bioglass in PDLLA under elevated temperatures resulted in the degradation of the matrix, leading to a reduction in the mechanical properties of the composites and in the molecular weight of the matrix. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy showed the presence of a peak at 1600 cm(-1) in the composite material, particularly when processed at elevated temperatures, whereas no peak at this wavelength was discernible for the pure PDLLA. Furthermore, time-based ATR-FTIR spectra taken at elevated temperatures on the TIPS-processed composites showed an increase in the intensity of the peak at 1600 cm(-1) and a concomitant reduction of the CO stretch peak at 1745 cm(-1) with time. This suggested the formation of a carboxylate salt by-products as a consequence of a reaction at the interface between the Bioglass filler and the PDLLA matrix. Therefore, the results confirmed that this degradation was not solely due to shear effects during the extrusion process. This work thereby supports the assertion that, in the presence of Bioglass filler particles, poly(alpha-hydroxyester)-based composites should not be processed at elevated temperatures.
生物活性、可生物降解的复合材料越来越多地被探索用于骨替代材料和组织工程支架。它们的性能不仅取决于填充剂和基质的性能，而且还取决于它们的相互作用。本研究研究了在高温下存在 Bioglass 颗粒填充剂时对聚（D，L-丙交酯）（PDLLA）基质的影响。不同填充剂含量的复合材料在升高的温度下通过共挤出进行复合，然后通过压缩成型进行比较，与通过热诱导相分离（TIPS）制备的类似组成的复合材料进行比较，TIPS 是一种低温处理途径。结果发现，在高温下将 Bioglass 包含在 PDLLA 中会导致基质降解，从而降低复合材料的机械性能和基质的分子量。衰减全反射傅里叶变换红外（ATR-FTIR）光谱显示复合材料中在 1600 cm(-1) 处存在一个峰，特别是在高温下处理时，而纯 PDLLA 中则没有该波长的峰。此外，在升高的温度下对 TIPS 处理的复合材料进行基于时间的 ATR-FTIR 光谱分析显示，在 1600 cm(-1) 处的峰强度增加，并且在时间过程中 1745 cm(-1)处的 CO 伸展峰减少。这表明 Bioglass 填充剂和 PDLLA 基质界面之间的反应形成了羧酸盐副产物。因此，结果证实这种降解不仅是由于挤出过程中的剪切效应所致。这项工作支持了这样的观点，即在 Bioglass 填充颗粒存在的情况下，基于聚（α-羟基酯）的复合材料不应在高温下进行加工。
