Volume 40, Issue 5

Advanced digital technologies are increasingly transforming the current landscape of polymer processing, paving the way towards far more efficient, resilient, and sustainable manufacturing practices. This paper reviews the methods applied in digitalization of the plastics processing industry, classified into different levels of digitalization: (i) offline process modeling and design, (ii) real-time data-feed digital shadows, (iii) the design and implementation of real digital twins and (iv) the interconnection of machinery to create holistically optimized smart factories. Initially, we introduce the basic technologies shared across the categories – sensors, soft sensors, Cyber-Physical Systems, Internet of Things and Control systems. In each digitalization category, we specify the core concept in general sense and how it fosters the industry; subsequently, we introduce case studies to illustrate the applications and the state-of-the-art of digitalization in the polymer processing industry. Each of the categories is, to some extent, being researched in a general (more descriptive) sense and has also been applied to specific tasks in polymer processing. The use cases demonstrate the benefits of digitalization, however, they are generally also lacking in terms of scalability, adaptability and generalizability; furthermore, there are potential applications where no digitalization has been demonstrated yet. Clearly, digitalization offers a significant opportunity for improving the whole plastics industry, with the benefits being demonstrated by the literature reviewed. While the technological basis for further digitalization already exists, the diversity of individual approaches and applications in polymer processing provides ample room for further research and development towards improvements that state-of-the-art methods in polymer processing cannot achieve.

Medical catheters are widely used in various treatment methods such as drainage, perfusion, blood collection, and play an indispensable role in medical therapy. Multi-lumen medical micro-catheters make many treatments more efficient and convenient. However, the extrusion-induced geometric distortion of the multi-lumen catheters is still unclear, making shape control remain heavily reliant on experience, which limits their manufacture and applications. This paper focuses on three-lumen medical micro-catheters (TLMMC), utilizing the computational fluid dynamics (CFD) method to conduct three-dimensional isothermal numerical simulations of the extrusion process. This study explores the extrusion-induced geometric distortion of microcapillaries within catheters. Results show that in the extrusion direction, a critical threshold occurs approximately 4 mm from the die outlet, where the melt transitions from being primarily influenced by die swell to being influenced by the stretching effect. The findings provide valuable insights for the manufacturing of TLMMC and holds broad application prospects in interventional diagnosis and treatment.

High-performance thermoplastic polymers, such as polyetheretherketone (PEEK), are frequently utilized in engineering applications, particularly when superior mechanical properties, enhanced thermal stability, and chemical resistance are required. However, their composites are subjected to process challenges, including even dispersion, process compatibility, and improved moisture absorption behaviour. This research aims to mitigate the disputes above and enhance the functional properties of PEEK composites by adding short hemp fiber through hot pressing technology. To enhance the fiber quality and reduce the moisture absorption behaviour, the hemp fiber (HF) undergoes sodium hydroxide (NaOH) surface treatment, and the final composites contain 0, 15, 30, and 45 wt% of short HF (treated). During the fabrication process, 5 % polyetherimide (PEI) was used as a compatibilizer to enhance the adhesive and thermal behaviour of the composite samples. The effectiveness of processing on the microstructural behaviour of the composite is analyzed via transmission electron microscopy (TEM), and HF is found to have a coarse and wide distribution, resulting in improved functional properties. The effect of HF content on the microstructural, moisture absorption, electrical properties, microhardness, and thermal stability of synthesized composites is investigated. The composite of PEEK with 45 wt% of short HF with 5 % PEI has low moisture absorption of 0.4 %, increased dielectric constant of 4, reduced surface resistance of 1.1 × 10 9  Ωcm, enhanced microhardness of 28 HV and improved thermal stability. It is recommended for Printed Circuit Boards (FPCBs) and microcircuit applications.

To address the complexity and high degree of idealization in the numerical simulation of polyurethane foaming in thermal insulation layers, a simulation model based on material parameters was developed. This model focuses on the dynamic variations in density and viscosity during the foaming process. Material properties are defined using a User-Defined Function (UDF), and the accuracy of the model was validated by comparing simulation results with experimental data. The results show that the average errors in simulated density and viscosity changes are 5.81 % and 7.94 %, respectively, when compared with experimental data. These results indicate that the model accurately captures the evolution of polyurethane foam properties during foaming. Finally, the accuracy of the model is further demonstrated through the application of the model to a specific refrigerator structure as a case study. This study provides valuable insights for analyzing the foaming and molding behavior of polyurethane in insulation layers for optimized process design.

This study investigates the mechanical performance of sandwich composites comprising basalt (B) and aramid (A) fiber-reinforced skins with a PVC foam core, focusing on the effects of fiber hybridization and stacking sequence. Tensile, flexural, and 25 J impact tests were conducted to evaluate monolithic and hybrid configurations. Monolithic Basalt (B 5 /PVC/B 5 ) exhibited lower tensile strength (average ∼109.5 MPa) with higher flexural modulus (average ∼36.7 GPa) compared to Aramid (A 5 /PVC/A 5 ) skins. Conversely, Aramid skins (A 5 /PVC/A 5 ) demonstrated higher flexural strain (average ∼1.35 %), indicating greater ductility. Hybrid configurations balanced these properties; the BA-PVC (B 3 A 2 /PVC/A 2 B 3 ) arrangement achieved optimal energy absorption (average ∼25 J) under impact, outperforming AB-PVC (A 2 B 3 /PVC/B 3 A 2 ) (average ∼20 J). Tensile testing revealed A 5 /PVC/A 5 had the highest strength (average ∼136.7 MPa), while B 5 /PVC/B 5 showed the highest strain (average ∼9.56 %). Flexural testing confirmed B 5 /PVC/B 5 possessed the highest strength (43.7 MPa) and modulus (36.7 GPa). Stacking sequence critically governed failure modes, with basalt-dominated exteriors prioritizing stiffness but suffering abrupt core shear failure, while Aramid exteriors enhanced damage tolerance through progressive matrix cracking and fiber bridging. The PVC core’s low shear modulus amplified delamination in stiff hybrids, underscoring interfacial adhesion as a key limitation. Findings reveal that the BA-PVC architecture (Aramid outer/Basalt inner) optimally balances strength, ductility, and impact resistance.

Styrene-isoprene-styrene (SIS) based hot melt pressure sensitive adhesives (HMPSAs) have high tack, high cohesion (at ambient temperature), and good adhesion to various substrates. In this study, we investigated the effects of styrene-isoprene diblock content in SIS copolymer on the characteristics of SIS-based HMPSAs and used them for labels. We found that styrene-isoprene (SI) diblock in a styrene-isoprene-styrene (SIS) copolymer improved adhesive properties and die cutability of self adhesive labels, which is one of the most significant properties for labels. The diblock copolymer reduces the storage modulus of adhesive compounds. As the modulus is low, it improves wettability to the surface, resulting in high tack and peel, which seems to be a predominant factor on labels. The SIS used in this study is classified into low diblock SIS and high diblock SIS.

Electrospinning is a simple and versatile technique for producing nanofibers. However, conventional single-nozzle devices have inherent limitations in preparing functional composite nanofiber materials. Although dual-nozzle electrospinning provides a direct method for fabricating composite fibers, the integration of dual nozzles into the electrospinning system distorts the electric field distribution. This distortion induces Coulomb repulsion between the uniformly charged jets, resulting in an uneven distribution of heterogeneous fibers in the composite membrane. This unevenness significantly compromises the structural integrity of the material. In this study, we systematically developed an electrospinning simulation model for electric field analysis and jet trajectory prediction. We elucidated the repulsion mechanism between electric field heterogeneity and Coulomb forces in a single-power-supply dual-nozzle system and proposed a dynamic scanning deposition strategy to address the technical challenges of producing heterogeneous fiber composites. This strategy enabled the formation of composite piezoelectric and conductive polymer nanofibers. The resulting composite nanofibers exhibit both high piezoelectricity (d33 = 21.7 pC/N) and electrical conductivity (0.0646 S/m), confirming the effectiveness of the dynamic scanning deposition approach. Supported by the experimental validation of simulation reliability, this study provides a theoretical basis for optimizing the single-power-supply dual-nozzle electrospinning process to produce heterogeneous nanofiber composites.

The final quality of 3D printed parts through Fused Deposition Modelling (FDM) depends on many parameters, which vary for the printing of different materials. The addition of carbon fibers to polylactic acid (PLA) enhances its strength while reducing its printability. Hence, selection of appropriate process parameters for printing carbon fiber reinforced PLA (CF-PLA) is essential. Many industrial applications require high strength along with better surface finished components. The current research studies the effect of the FDM variables printing temperature, printing speed, infill density, and layer thickness on the tensile strength and surface roughness of a 3D printed part. The experiments were designed using the response surface methodology, and 31 experimental trials were generated. The tensile strength of the 3D printed component was influenced by the printing temperature, printing speed, and infill density, while layer thickness had no significant effect on the tensile strength. Similarly, for surface roughness, the infill density has no significant effect, but the other parameters have a significant influence. The optimum process parameters yielding a maximum tensile strength of 39.54 MPa and a minimum of surface roughness of 13.77 μm are printing temperature of 247.4 °C, printing speed of 40 mm/min, infill density of 91.8 % and layer thickness of 0.2 mm.

This study aims to evaluate the behaviour of polyvinyl chloride (PVC)-based nanocomposites to determine the optimal conditions for enhancing their morphological, thermal and mechanical properties. The study focuses on the impact of combining two categories of reinforcements on the properties of PVC-based nanocomposites. The results highlight a significant synergy between Org@Mag fillers and epoxy-functionalized graphene. The results of X-ray diffraction (XRD) analysis and micrographs obtained by transmission and scanning electron microscopies (TEM and SEM) of the various nanocomposites developed reveal significantly improved dispersion of graphene layers and clay sheets in the polyvinyl chloride (PVC) matrix. The Org@Mag/Gr combination led to a tendency for the development of a co-continuous PVC morphology, optimizing the diffusion and distribution of reinforcements in the matrix. PVC-based nanocomposites exhibit significantly superior mechanical behavior to pure PVC, particularly due to the incorporation of montmorillonite and graphene hybrids. The incorporation of nanometric fillers increases the thermal stability of PVC. The measured strength and modulus values confirm this trend.

The study explores the effect of rice husk biofiller on the hydration, mechanical, and wear properties of ternary fiber-reinforced epoxy hybrid composites composed of jute, kevlar, and basalt fibers. Composites were fabricated via hand layup and compression, with varying stacking sequences and biofiller content (2 % and 4 %). FTIR analysis confirmed that biofiller addition and fiber stacking variations did not alter composite functional groups. Water absorption tests showed that the composite with stacking sequence K-J-B-K-J-J-K-B-J-K and 4 % biofiller (H4) exhibited the lowest water uptake at 3.2 %, indicating enhanced hydration resistance. Mechanical testing revealed that H4 also achieved the highest tensile strength (137.9 N/mm 2 ), flexural strength (225.9 N/mm 2 ), and impact strength (179 kJ/m 2 ), demonstrating superior load-bearing and toughness characteristics. Conversely, the composite with stacking sequence B-J-K-B-J-J-B-K-J-B and 4 % biofiller (H3) displayed the highest hardness (86.2 Shore D) and the lowest coefficient of friction (0.30), signifying excellent wear resistance. These results suggest that the synergistic combination of ternary fiber stacking and rice husk biofiller optimizes composite performance, making H3 and H4 promising candidates for lightweight, durable automotive interior and exterior components, advancing sustainable composite material development.

The injection moulding of Polymethyl Methacrylate (PMMA) is crucial for producing high-precision optical components where isotropic material properties are essential for uniform optical performance. Anisotropy, manifested as variations in volumetric shrinkage (Vs), residual stress (Rs), warpage, and density difference ( δ d), can compromise dimensional stability and optical clarity. This study investigates the influence of key injection moulding parameters on the anisotropy of 3 mm and 6 mm thick PMMA disks. A novel sectional probing technique was developed to assess core-to-surface variations along the z -axis, offering unique insights into internal anisotropy gradients that conventional methods often overlook. We employed a synergistic approach combining Design of Experiments (DOE) with Taguchi’s method, finite element simulation using Moldflow, and multi-objective optimization via genetic algorithms to identify optimal process conditions. Analysis of Variance (ANOVA) revealed that melt temperature and mould temperature are the most significant factors, accounting for 60 % and 36 % of the variance in Vs and Rs, respectively. A highly predictive linear regression model ( R Pred . 2 ${R}_{\text{Pred}.}^{2}$ >0.95) was developed, demonstrating that optimization reduced Vs by 4 % and Rs by 9 % compared to the initial trials. The study also found that part thickness significantly amplifies anisotropy, with 6 mm parts exhibiting variations of 54 % increase in Vs, 54 % decrease in Rs and a 43 % rise in δ d compared to 3 mm parts. Experimental validation using a linear polarized microscope and dial gauge measurements confirmed these simulation results, showing reduced birefringence and shrinkage in the optimized parts. The experimental shrinkage values were within 0.02 mm and 0.06 mm of the simulated values for the 3 mm and 6 mm disks, respectively. This work not only demonstrates the efficacy of integrating DOE, simulation, and optimization but also highlights the critical role of part thickness and the novelty of the sectional probing method in elucidating anisotropy mechanisms, providing a robust methodology for producing isotropic PMMA parts for advanced optical applications such as lenses and light guides.

In this study, hybrid biocomposites based on polylactic acid (PLA) with (0–40 %) pine fiber (F) and (0–40 %) CaCO 3 (C) were first compounded by twin-screw extrusion, followed by compression molding to determine their properties in terms of tension, bending, and impact, as well as fluidity. In general, adding fillers resulted in improved tensile and flexural modulus (60–105 %) compared to neat PLA. These results were used to optimize the formulation and produce cutlery via injection molding. These samples were further characterized using SEM, FTIR, DSC, and TGA to obtain additional information. SEM images showed that micronized CaCO 3 treated with stearic acid promoted their adhesion with the PLA matrix, as confirmed by FTIR. On the other hand, DSC results showed that the presence of fiber and/or particles had a negligible effect on the transition temperatures (Tg and Tm), but the PLA crystallinity was modified. Finally, the production of cutlery was successfully carried out using optimized formulations and processing conditions, confirming that these materials can be utilized in various food applications.

This study investigates the synergistic enhancement of Mode I and Mode II interlaminar fracture toughness (G IC and G IIC ) in basalt/Kevlar hybrid fiber-reinforced epoxy composites through multiwall carbon nanotube (MWCNT) integration. Hybrid laminates with two stacking sequences (B5K10B5 and K5B10K5) were fabricated via vacuum-assisted resin transfer molding (VARTM), incorporating MWCNTs at 0.1, 0.25, and 0.5 wt.% in the epoxy matrix. Fracture behavior was characterized using double cantilever beam (DCB) and end-notched flexure (ENF) tests, complemented by scanning electron microscopy (SEM) to elucidate failure mechanisms. Key results demonstrate that 0.1 wt.% MWCNTs optimally enhanced fracture resistance: K5B10K5 composites achieved 32.9 % G IC improvement (923.42 J m −2 ) and 22.9 % G IIC increase in mode II fracture toughness. B5K10B5 composites exhibited superior baseline G IC (998.61 J m −2 vs. K5B10K5’s 619.47 J m −2 ) but lower G IIC sensitivity to MWCNTs. Performance degradation occurred at 0.5 wt.% MWCNTs due to agglomeration, reducing G IC by 22.5 % in B5K10B5. Conversely, K5B10K5 showed exceptional G IIC (4481.06 J m −2 ) at 0.5 wt.%, attributed to crack bifurcation and shear-induced frictional sliding. SEM analysis confirmed that MWCNTs enhance toughness via crack bridging and fiber-matrix interlocking at optimal dispersion (0.1 wt.%), while agglomerates degraded Mode I performance but partially increased Mode II resistance.

The use of mechanical property-improving fillers has resulted in defect formation in 3D-printed structures. To the best of our knowledge, this study is the first to modify poly lactic acid (PLA) filaments in bulk by integrating 7–13 wt% holy basil and 0.1–0.4 wt% graphene additive. The results showed a 22–31 % increase in the melt flow index (MFI) of the composites. The filaments’ compositional changes were then submitted to rheological testing to assess the influence on filament structure. To solve common printing difficulties, such as mid-print model voids, we developed a strategy for optimizing extrusion settings using Cura slicing software. In addition, we created an efficient technique of MFI testing of 3D-printed filament systems that does not require the use of expensive laboratory equipment, allowing us to use additional filament property assessment methods. This highlights the need to tune the filament’s extrusion speed in order to improve accuracy and print quality for 3D printing additive prototyping.

Double-shell phase change capsules composed of organically modified montmorillonite (OMMT), chitosan (CS), and paraffin wax (PCM) were fabricated using complex coacervation and dry mixing methods. Paraffin served as the core material, CS as the organic shell, and OMMT as the inorganic flame-retardant component. The morphology, thermal stability, flame retardancy, and phase transition kinetics of the capsules were systematically examined. Results indicated that when the mass ratio of OMMT to CS/PCM was 1:1, OMMT was uniformly dispersed on the capsule surface, leading to optimal performance. Thermogravimetric (TG) and microscale combustion calorimetry (MCC) analyses revealed that the incorporation of OMMT significantly improved the thermal stability of the capsules, increased char residue, and markedly reduced both the peak heat release rate (PHRR) and total heat release (THR). The phase change behavior was elucidated through differential scanning calorimetry (DSC). Furthermore, Kissinger’s kinetic model was applied to determine the activation energy, which was found to be higher in the OMMT-containing capsules, suggesting that OMMT addition restricts molecular thermal motion. This study offers both theoretical insights and practical guidelines for designing composite phase change materials that combine high energy storage efficiency with enhanced flame retardancy.