The paper presents technical conditions related to the implementation of component processes of mechanical recycling of thermoplastic materials with a porous structure. Significant influence of the ...type and form of porous waste on the efficiency of the processes of their cutting, grinding, dosing and also of secondary injection molding process was indicated. It has been shown that by appropriate selection of technical conditions, it is possible to produce molding parts, without the use the holding phase in the secondary injection molding and with complete elimination re-extrusion process. Keywords: porous thermoplastics, cutting, grinding, mechanical recycling, secondary injection molding. Przedstawiono uwarunkowania techniczne zwiazane z realizacja procesow skladowych recyklingu mechanicznego porowatych tworzyw termoplastycznych. Wskazano na istotny wplyw rodzaju i postaci odpadow porowatych na efektywnosc przebiegu procesow ciecia, rozdrabniania, dozowania, a takze wtornego przetworstwa wtryskowego. Wykazano, ze odpowiedni dobor warunkow technicznych umozliwia wytworzenie wyprasek wtornych z pominieciem fazy docisku i etapu regranulowania recyklatow. Slowa kluczowe: termoplasty porowate, ciecie, rozdrabnianie, recykling mechaniczny, wtorne wtryskiwanie.
Experimental studies have been performed on the flow of wood plastic composite in the starve fed single screw extrusion. The extrusion process of polypropylene (PP) composite with various wood flour ...content at different operating conditions and level of starvation has been investigated. Melting and flow of the material were evaluated using "Screw Pulling-out Technique". It was stated that the flow of wood plastic composite (i.e., conveying of the solid plastic material, melting and melt flow) in the starve fed extrusion is different from the flow of wood plastic composite in the flood fed extrusion. Also, it differs from the flow of thermoplastics in the starve fed extrusion. Melting in the partialy filled region is similar to the melting of thermoplastics in this region, i.e., it consists mainly in the conduction, while melting in the fully filled region is dependent on the wood flour content. At high content of wood flour, melting does not proceed according to the well-known Tadmor model, and one -dimensional melting is observed. At low wood flour content, the applicability of Tadmor model is clearly seen. Keywords: starve fed single screw extrusion, wood plastics composites, melting. Wykonano badania doswiadczalne przeplywu polimerowych kompozytow drzewnych w procesie wytlaczania jednoslimakowego z dozowanym zasilaniem wytlaczarki. Prowadzono proces wytlaczania kompozytow polipropylenowych (PP) z roznym udzialem masowym maczki drzewnej, w roznych warunkach technologicznych przetworstwa i na roznym poziomie dozowania tworzywa. Na podstawie "zimnego eksperymentu" wytlaczania z zastosowaniem techniki "wyciagania slimaka" oceniano przebieg uplastyczniania i przeplywu kompozytu. Stwierdzono, ze przeplyw (tj. transport tworzywa w stanie stalym, uplastycznianie oraz przeplyw tworzywa w stanie uplastycznionym) polimerowych kompozytow drzewnych w procesie wytlaczania z dozowanym zasilaniem przebiega odmiennie niz przeplyw w klasycznym procesie wytlaczania bez dozowania. Ponadto, rozni sie on od przeplywu tworzyw termoplastycznych w procesie z dozowanym zasilaniem wytlaczarki. Mechanizm uplastyczniania w strefie niecalkowitego wypelnienia slimaka jest podobny do mechanizmu uplastyczniania tworzyw termoplastycznych, polegajacego na przewodzeniu. Natomiast uplastycznianie kompozytu w strefie calkowitego wypelnienia slimaka jest zalezne od zawartosci maczki drzewnej w osnowie PP. W wypadku duzej zawartosci maczki drzewnej nie obserwuje sie znanego mechanizmu uplastyczniania Tadmora. Wystepuje wowczas mechanizm uplastyczniania jednokierunkowego. Mechanizm Tadmora uwidacznia sie w wypadku mniejszej zawartosci maczki drzewnej w kompozycie PP. Slowa kluczowe: wytlaczanie jednoslimakowe z dozowaniem, polimerowe kompozyty drzewne, mechanizm uplastyczniania.
In the last decade, design and material innovations for manufacturing composites have reached new heights. Thermoplastic polymers and their composites have become the most in-demand materials in ...recent times as they provide numerous advantages over thermoset composites. Thermoplastic polymers have a high damage tolerance, high impact resistance, recyclability, formability, weldability, repairability, and cost-effectiveness compared with thermoset composites. Thermoplastic polymers and composites are widely used in automotive, aerospace, electrical and electronics, industrial, and medical applications. Thermoplastic composites are estimated to grow from USD 28.0 billion in 2019 to USD 36.0 billion by 2024. High-performance thermoplastic materials are used in conjunction with a multitude of manufacturing processes like injection moulding, thermoforming, prepreg, liquid injection processes, automated tape placement, filament winding, pultrusion, additive manufacturing, and other processes. The material limits, design, and assembly requirements, as well as the processing constraints, are significantly important for the realisation of novel product development using a manufacturing process by simultaneously optimising reliability, safety, and other performance-related issues. The current thermoplastic material systems and manufacturing techniques still have plenty of room for optimisation and advancement. This reprint presents the latest scientific and technical advances in thermoplastic materials and their composites, processing, characterisation, product development, and manufacturing process parameter optimisations.
This work addresses the large strain behaviors of thermoplastic polyurethanes (TPUs) spanning a range of fractions of hard and soft contents in both experiment and theoretical modeling. The key ...mechanical features involve a combination of elasticity and inelasticity, and are quantified experimentally under a broad variety of loading scenarios. A finite deformation constitutive model is then presented to capture the main features of the stress-strain data, which are strongly dependent on fractions of hard and soft contents. The stress-strain behavior of these TPUs is characterized by highly nonlinear rate-dependent hyperelastic-viscoplasticity, in which substantial energy dissipation is accompanied by shape recovery as well as softening. Agreement between the model and the experimental data for the representative TPUs provides physical insight into the underlying deformation mechanisms in this important class of soft materials that exhibit both elastomeric and plastomeric characteristics.
Large strain behavior of thermoplastic polyurethanes spanning a range of fractions of hard and soft segment contents: shape recovery and energy dissipation upon cyclic loading conditions are highly dependent on the fractions of hard and soft contents, spanning the range from glassy to rubbery polymers. Display omitted
•Large strain behavior of thermoplastic polyurethanes is examined under various loading scenarios•Mechanical behavior characterized by nonlinear rate-dependent hyperelastic-viscoplasticity•Finite deformation constitutive model is presented that captures mechanical response•Interpretation of constitute model provides insight into deformation mechanisms
The aim of the present study was to investigate starch-based materials, prepared in an environmentally friendly way and from renewable resources, suitable for the development of biodegradable active ...food packaging. For this purpose, a bioactive compound (thymol) was incorporated into thermoplastic starch (TPS) and a TPS blend with poly (ε-caprolactone) (TPS-PCL) by the supercritical COsub.2 (scCOsub.2) impregnation process. Impregnation experiments with scCOsub.2 were carried out at a pressure of 30 MPa and temperatures in the range of 40-100 °C during 1 to 20 h. The structural, morphological, and thermal properties of the obtained materials were comprehensively evaluated. Bioactive component release kinetic studies were performed in water at 6 °C and 25 °C. It was shown that the scCOsub.2 impregnation process could be successfully employed for thymol loading into TPS and TPS-PCL. The process was significantly influenced by the operating temperature and time as well as content of PCL. The samples showed a controlled release of thymol within seven days with a higher amount of released thymol from the TPS-PCL blend. The obtained materials are solvent-free and release the bioactive component in a controlled manner.
Aromatic nucleophilic substitution polymerization was used to synthesize five poly(ether nitrile imide)s (PENIs) that include benzonitrile and bulky cardo groups from a mixture of phenolphthalein ...(PP), 4,4'-bis(4-fluorophthalimide) diphenyl ether (4,4'-BFPI), and 2,6-difluorobenzonitrile (DFBN). The structure and properties relationship of PENIs with different ratios of DFBN and 4,4'-BFPI was explored. It was found that the glass transition temperature (T.sub.g) of PENIs decreased from 280 to 260degrees C, while the temperature of 5% thermal weight loss (T.sub.5%) in N.sub.2 increased from 429 to 453degreesC as the benzonitrile content in PENI increased. The produced PENI films had good mechanical characteristics, including tensile strengths of 103-112 MPa, elongations at break of 5.6%8.2%, and tensile moduli of 2.9-3.4 GPa. Furthermore, the solubility and melt processability were also improved with the introduction of the benzonitrile group. Compared with poly(ether ketone imide)s (PEKIs) and poly(ether sulfone imide)s (PESIs), PENIs with benzonitrile displayed higher T.sub.g, tensile modules, and lower complex viscosity.
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![Supercritical CO[sub.2] Imp...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2073-4360/small "Supercritical CO[sub.2] Impregnation of Thymol in Thermoplastic Starch-Based Blends: Chemico-Physical Properties and Release Kinetics")
