Assessing Fast Structure Formation Processes in Isotactic Polypropylene with a Combination of Nanofocus X-ray Diffraction and In Situ Nanocalorimetry

Evaluating the Injection Moulding of Plastic Parts Using In Situ Time-Resolved Small-Angle X-ray Scattering Techniques

In this study, we describe the design and fabrication of an industrial injection moulding system that can be mounted and used on the NCD-SWEET small-angle X-ray scattering beamline at ALBA. We show how highly useful time-resolved data can be obtained using this system. We are able to evaluate the fraction of the material in the mould cavity and identify the first material to solidify and how this varies with the injection temperature. The design follows current industrial practice and provides opportunities to collect time-resolved data at several points within the mould cavity so that we can build up a 4D perspective of the morphology and its temporal development. The quantitative data obtained will prove invaluable for the optimisation of the next generation of injection moulding techniques. This preliminary work used results from the injection moulding of a general-purpose isotactic polypropylene.

AC/DC Thermal Nano-Analyzer Compatible with Bulk Liquid Measurements

Nanocalorimetry, or thermal nano-analysis, is a powerful tool for fast thermal processing and thermodynamic analysis of materials at the nanoscale. Despite multiple reports of successful applications in the material sciences to study phase transitions in metals and polymers, thermodynamic analysis of biological systems in their natural microenvironment has not been achieved yet. Simply scaling down traditional calorimetric techniques, although beneficial for material sciences, is not always appropriate for biological objects, which cannot be removed out of their native biological environment or be miniaturized to suit instrument limitations. Thermal analysis at micro- or nano-scale immersed in bulk liquid media has not yet been possible. Here, we report an AC/DC modulated thermal nano-analyzer capable of detecting nanogram quantities of material in bulk liquids. The detection principle used in our custom-build instrument utilizes localized heat waves, which under certain conditions confine the measurement area to the surface layer of the sample in the close vicinity of the sensing element. To illustrate the sensitivity and quantitative capabilities of the instrument we used model materials with detectable phase transitions. Here, we report ca. 10⁶ improvement in the thermal analysis sensitivity over a traditional DSC instrument. Interestingly, fundamental thermal properties of the material can be determined independently from heat flow in DC (direct current) mode, by using the AC (alternating current) component of the modulated heat in AC/DC mode. The thermal high-frequency AC modulation mode might be especially useful for investigating thermal transitions on the surface of material, because of the ability to control the depth of penetration of AC-modulated heat and hence the depth of thermal sensing. The high-frequency AC mode might potentially expand the range of applications to the surface analysis of bulk materials or liquid-solid interfaces.

The Influence of Metal Lithium and Alkyl Chain in the Nucleating Agent Lauroyloxy-Substituted Aryl Aluminum Phosphate on the Crystallization and Optical Properties for iPP

In this work, a kind of aryl phosphate salt nucleating agent (APAl-12C) was synthesized, which was replaced in the hydroxyl group on the aluminum hydroxy bis [2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] (APAl-OH) by lauroyloxy, which could improve the dispersion between the nucleating agent and the iPP matrix and reduce the migration potential of the nucleating agent in the iPP matrix by increasing the molecular weight. The structure of the nucleating agent APAl-12C was analyzed by fourier infrared spectroscopy (FT-IR ) and ¹H NMR. The differential scanning calorimeter (DSC) results indicated that the addition of APAl-OH or APAl-12C alone was inferior to the commercial nucleating agent NA-21 (compounds of APAl-OH and Lithium laurate) in terms of the crystallization behavior, which may be due to the importance of metal Li in the crystallization property. Thus, the iPP/A12C-Li composites were prepared with APAl-12C, lithium laurate (lilaurate) and the iPP matrix. The crystallization behavior, morphology, optical and mechanical properties for the iPP/A12C-Li composites were systematically studied and compared with that of the iPP/NA-21 composite. Among the iPP/A12C-Li composites with the addition of 0.5 wt%, APAl-12C/Lilaurate had the fastest crystallization rate and reduced the haze value of the neat iPP from 36.03% to 9.89% without changing the clarity, which was better than that of the iPP/NA-21 composite. This was due to the weakening of the polarity of the APAl-12C after lauroyloxy substitution and better dispersion in the iPP matrix, resulting in a significant improvement in the optical properties.