Dynamic Light Scattering by Foamed Polymers during Preparation of Scaffold Prototypes: Events Statistics Analysis versus Evaluation of Correlation Time in Data Interpretation

Abstract

Polylactide foaming as the key stage in laboratory preparation of highly porous biocompatible matrices used as scaffold prototypes was monitored based the effect of dynamic light scattering in expanding polylactide foams. Intensity fluctuations of scattered laser radiation in the course of foam expansion were analyzed using ensemble-averaged estimates of the speckle lifetime within a running window in the time domain. It was found that, in contrast to the commonly used correlation time of intensity fluctuations, the values of the average speckle lifetime are invariant with respect to the type of dynamics of phase fluctuations of partial components in scattered radiation. This makes it possible to relate this parameter to microscopic mobility of interphase boundaries in the foam in the absence of a priori information on the law of motion relating these boundaries at the microscopic level. The proposed approach in combination with the developed phenomenological model describing the relationship between the average speckle lifetime and the current values of the foam volume, as well as its first-time derivative made it possible to interpret the features of foam structure formation.

Оптическая Диффузионная Диагностика Эволюционирующих Полимерных Пен

“…1, а) видеопотока, и синхронизированного по времени мгновенного изображения эволюционирующей полилактидной пены (камера ToupTec CAM1080PHB, позиция 4 на рис. 1, а); анализ получаемых спекл-коррелометрических данных осуществлялся с использованием оценок значений среднего времени существования динамических спеклов в процессе эволюции пены [21]; детали проведения эксперимента и анализа полученных данных обсуждены в разд. 3;…”

“…С другой стороны, в соответствии с [21] между оптическими транспортными параметрами эволюционирующей пены и текущим средним размером поры существует взаимосвязь (см. выражение (1)) l, l * ∝ D .…”

“…выражение (1)) l, l * ∝ D . Используя результаты моделирования [21], установим взаимосвязь между характерным размером расширяющейся пены L f , транспортной длиной распространения излучения в пене l * и средним числом актов рассеяния зондирующего излучения в пене:…”

Optical diffusion diagnostics of evolving polymer foams

“…1, a) , and a time-synchronized snapshot of an evolving polylactide foam (ToupTec CAM1080PHB camera, position 4 in Fig. 1, a); analysis of the obtained speckle-correlometric data was carried out using estimates of the values of the average lifetime of dynamic speckles in the process of foam evolution [21]; details of the experiment and analysis of the obtained data are discussed in Section 3;…”

“…Ref. [21] considers a different approach to the characterization of microscopic dynamics of scattering centers in nonstationary media using the experimental data on the characteristic time scales of laser radiation fluctuations. It was proposed to use as a characteristic time scale not τ c , but the mean lifetime τ b of dynamic speckle in the recorded light field at the analyzed stage of the scattering system evolution.…”