Interactions between sorbitol‐type nucleator and additives for polypropylene

Evaluation of microplastics release from solar water disinfection poly(ethylene terephthalate) and polypropylene containers

Public health concern associated with the ingestion of microplastics (MPs) released from water packaging materials is increasing. The use of plastic materials for solar disinfection (SODIS) containers has also raised concerns in the SODIS community due to the lack of studies evaluating the presence of MPs in the treated water. In this work, the migration of MPs from poly(ethylene terephthalate, PET) bottles and polypropylene (PP) translucent and transparent jerrycan containers (TJC) into water under natural weathering was investigated using micro-reflectance Fourier Transform Infrared Spectroscopy (µ-FTIR). Containers exposed to sunlight for three months became photodegraded, releasing micro-sized fragments identified as PET, PP and high-density polyethylene (HDPE, from the screw-caps), although with varying degrees of weathering. It is noteworthy that the presence of a clarifying additive in PP formulation did not seem to impact the release of MPs from the containers. The study showed that PP TJC containers released more MPs than PET bottles. Finally, the size of MPs was measured to determine their fate upon ingestion and highlights the need for further studies to understand the safety of these plastic containers for SODIS.

Identifying, Quantifying, and Recovering a Sorbitol-Type Petrochemical Additive in Industrial Wastewater and Its Subsequent Application in a Polymeric Matrix as a Nucleating Agent

Currently, polypropylene (PP) is highlighted using sorbitol-based clarifying agents since these agents are high quality, low cost, and work as a barrier against moisture, which makes PP ideal for packaging food, beverages, and medical products, among others. The use of analytical methods capable of recovering these additives in wastewater streams and then reusing them in the PP clarification stage represents an innovative methodology that makes a substantial contribution to the circular economy of the PP production industry. In this study, a method of extraction and recovery of the Millad NX 8000 was developed. The additive was recovered using GC-MS and extracted with an activated carbon column plus glass fiber, using an injection molded sample, obtaining a recovery rate greater than 96%. TGA, DSC, and FTIR were used to evaluate the recovered additive's glass transitions and purity. The thermal degradation of the recovered additive was found to be between 340 and 420 °C, with a melting temperature of 246 °C, adopting the same behavior as the pure additive. In FTIR, the characteristic absorption peak of Millad NX 8000 was observed at 1073 cm^-1, which indicates the purity of the extracted compound. Therefore, this work develops a new additive recovery methodology with high purity to regulate the crystallization behavior and of PP.

Gelation and Crystallization Phenomena in Polyethylene Plastomers Modified with Waxes

Polyethylene (PE) plastomers, single-site catalyst-based homogeneous linear low-density PEs (LLDPEs), combine low crystallinity, softness, and elasticity, making them ideal candidates for numerous applications such as hot-melt adhesives (HMA). As plastomers crystallize rather slowly, a number of possible low molecular weight polyolefin components were tested to accelerate solidification. An ideal modifier should accelerate solidification while maintaining transparency and softness of the base polymer. A Queo plastomer type was modified with different PE and PP waxes at concentrations of 5 to 25 wt.-%. Next to conventional calorimetry, a rheological technique was applied to study solidification. The resulting morphology was studied by atomic force microscopy, and the final compositions were investigated regarding their mechanical and optical performance. Accelerated solidification was observed in all cases, but a quite different course of structure formation could be concluded. PE waxes dissolve in the melt state, forming a lamellar network during cooling, whereas PP waxes form a heterogeneous blend in the melt for which the wax droplets solidify before the matrix. The particulate-type modification by the PP wax also affects stiffness less while retaining transparency better.