Melting Crystallization Temperature Research Articles

Eco-friendly zinc-metal-organic framework as a nucleating agent for poly (lactic acid)

Eco-friendly poly(L-lactic acid) (PLA) can be made more versatile, and its crystallization rate is accelerated by adding Zinc-based metal-organic framework (Zn-MOF) particles. Using differential scanning calorimetry (DSC), the non-isothermal melt crystallization behavior of biodegradable PLA nucleated by 0.3 to 3 wt% of Zn-MOF was examined. The non-isothermal melt crystallization kinetics parameters were determined using a modified Avrami model and Mo approach. Zn-MOF dramatically accelerated the crystallization process, as evidenced by several non-isothermal crystallization metrics, including the crystallization half-time and crystallization rate constant. The melt crystallization temperatures of the PLA-Zn-MOF composites, with contents of 0.7 and 1 wt%, were increased by 21 °C compared to the neat PLA. Using the Friedman isoconversional kinetic method, the neat PLA and PLA-Zn-MOF composites' effective activation energy values, ∆E, were determined. The ∆E values of PLA-Zn-MOF from 0.3 to 1 wt% Zn-MOF composites were lower than that of neat PLA. Moreover, polarized optical microscopy revealed the formation of numerous small-sized PLA spherulites upon Zn-MOF addition. The results indicate that the Zn-MOF (at concentrations of 0.7 to 1.0 wt%) can be used as an efficient nucleating agent for PLA, where it increases the melt crystallization temperature, nucleation density, and crystallinity without changing the crystalline structure, while also significantly reduces the effective activation energy and the size of spherulites. Additionally, scanning electron microscopy confirms good dispersion of Zn-MOF (0.3 to 1 wt%) within the PLA matrix.

Investigating gradient temperature control for enhanced interfacial bonding behavior in material extrusion 3D printing continuous fiber reinforced polymer composites

Interlayer delamination is a significant concern for composites manufactured by fused filament fabrication (FFF) process. To address the problem of interlayer delamination and enhance the macro-mechanical properties of FFF fiber composites, it is necessary to improve the adhesive bonding in the manufacturing process. Therefore, a novel method is provided to improve the interfacial bonding behavior of composites by controlling the nozzle temperature gradients in FFF composites along the build directions during the process. Results showed that the value of the first reheating peaks, in thermal history curves under gradient nozzle temperature settings, reached the effective temperature ranges (between melting temperatures and crystallization temperature). This enhanced the adhesive bonding between each layer. Finally, both experimental and theoretical approaches confirmed that the proposed method could enhance the interfacial behavior of FFF continuous fiber filled composites.

A Method for Predicting the Melting Temperature of Ionic Compounds.

Predicting the melting temperature of materials has always been a topic of great concern. This article proposes an alternative model for determining the melting temperature of materials based on the main idea of the Lindemann melting criterion combined with the first-principles calculations of density functional theory. To verify the accuracy of the melting model, this article selected typical ionic crystals of MgO and 10 alkali metal halides as the validation objects. The calculation results indicate that the melting temperature of the MgO crystals and I-VII compounds is in good agreement with the experimental results.

Effect of comonomer loading on the thermal and mechanical properties of biobased copolyamides PA6/PA56

With bio-renewable and environmentally friendly nature, biobased polyamides have emerged as attractive alternatives to traditional petroleum-derived polymers. However, poor thermal and mechanical performance, high costs, and limited scalability significantly hinder their practical applications. Herein, a series of biobased copolyamides PA6/PA56 (CoPAs) were successfully synthesized from caprolactam, adipic acid, and the lysine-derived biobased monomers 1,5-pentanediamine. The copolyamides were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (1H NMR), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), rheological analysis, mechanical testing, and scanning electron microscopy (SEM). The result shows the α to γ transition in the crystalline form of the copolyamides with comonomer loading. The melting temperature, crystallization temperature, and crystallinity gradually decrease due to the introduction of the odd-even structure, causing deviation in amide positions and reducing hydrogen bond formation between molecular chains. Furthermore, variable-temperature infrared (VTIR) analysis and density functional theory (DFT) calculations further confirm a decrease in intermolecular forces. Importantly, the mobility of the molecular chains in the amorphous region is significantly improved, endowing the copolyamides with sufficient degrees of freedom to cope with externally applied strains. Moreover, significant entanglement facilitates effective stress transfer during stretching. As a result, the synthesized copolyamides achieve a high strength of 51 MPa and a remarkable toughness of 199 MJ/m3, without sacrificing thermal stability and processing properties. These biobased CoPAs show great potential and prospects in the field of high-performance thermoplastic materials, films, and textiles.

Effect of PCL chain length on rheological and mechanical properties of PCL‐PDMS‐PCL triblock copolymer films

AbstractThe polycaprolactone‐polydimethylsiloxane‐polycaprolactone (PCL‐PDMS‐PCL) triblock copolymer films of variable PCL chain are analyzed for rheological characteristics in this paper. The dynamics of viscoelastic behavior of photocrosslinked films above their crystal melting temperature (Tcm) is measured using oscillatory shear rheology experiments. The frequency sweep tests are analyzed at 0.1% strain as obtained from linear viscoelastic region. Shear thinning is observed in the study of complex viscosity. It has been noted that viscosity rises with increase in crosslink density and decrease in with PCL chain length. Time‐dependent effect on the copolymer films has been analyzed by creep recovery behavior. The Burgers model is fitted in creep compliance data to analyze its viscoelastic and viscous region. An examination of structure recovery revealed that recovery increased as PCL chain length decreased. Tensile strength and percentage elongation are studied at ambient conditions with a universal testing machine, while storage modulus and tan δ are analyzed by a dynamic mechanical analyzer at varying temperatures.

Influence of Complex Plasticizer on Plasticizing Effects and Rheological Properties of Plasticized Poly(Vinyl Alcohol)

AbstractPoly(vinyl alcohol) (PVA) was modified using D‐mannitol (DM) and 1‐butyl‐3‐methylimidazole bromide (BMIMBr) as the complex plasticizer (DB), and PVA/DB composite was prepared. The plasticizing effect of DB on PVA was studied by Fourier transform infrared spectroscopy (FT‐IR), differntial scanning calorimetry (DSC), thermos gravimetric analysis (TGA) and melt flow indexer (MI). FT‐IR analysis indicated that Br− of BMIMBr and OH of DM could form H‐bonds with OH of PVA. With the increase of DB, the melt temperature (Tm2) and crystallization temperature (Tc1) of PVA/DB composite decreased, the initial thermal decomposition temperatures (Td), thermal processing window (ΔT) and MI values increased respectively. Based on above studies, the influence of DB content on rheological properties of PVA/DB composite was investigated by the capillary rheometer. The result displayed that apparent viscosity of PVA/DB composite decreased with increasing DB content, shear rate and measured temperature. The non‐Newtonian index (n) increased and structural viscosity index (Δη) decreased with the increase of measured temperature and DB. The viscous flow activation energy (Eη) decreased as the shear rate and DB content increased. When the measured temperature, DB content and shear rate were in the range of Tm2+30 −Tm2+35 °C, 40–50 wt% and 764.8–1504.9 s−1, respectively, the spinnability of PVA/DB composite was optimal, which will lay a theoretical foundation for the exploration of melt spinning process in the future.

Lipase-catalyzed interesterification of Sunite sheep tail fat and flaxseed oil provides a fat having a unique fatty acid content and favorable physicochemical and nutritional properties.

The aim of this study is to combine flaxseed oil (FO), rich in α-linolenic acid (ALA), with Sunite sheep tail fat (STF) through a lipase-catalyzed transesterification reaction, in order to produce an edible oil with a fatty acid ratio suitable for human needs. Initially, the optimal conditions for esterification were determined using the Box-Behnken design, with the measurement criterion being the content of ALA at the sn-2 position. The results indicated that the highest content of sn-2 ALA was obtained under the conditions of using 6.8 wt% Lipozyme®RMIM as the catalyst, a reaction temperature of 57°C, a reaction time of 3.3 h, and a substrate mass ratio of 5.6:4.4 for STF and FO. This led to the rapid breaking and recombining of molecular bonds, resulting in the interesterified fat (IF) with the highest content of ALA at the sn-2 position. Comparing STF and FO, IF exhibited excellent fatty acid composition and content. Furthermore, IF had a lower melting point and crystallization temperature compared to STF, and its solid fat content decreased with increasing temperature, completely melting at temperatures above 30°C. Thus, IF is a synthesized fat with excellent properties from both animal and vegetable sources.

Synthesis and characterization of long carbon chain polyamide 1012 modified polyamide 6 via melt copolymerization

Polyamide6 is a vital high-performance commercial engineering thermoplastics polymer, but it exhibits low toughness and high hydrophilicity. To improve its disadvantages, the facile melt co-polycondensation method was proposed to synthesis a novel polyamides 6-1012 copolymers (PA6-1012) with different PA1012 salt loading. Experimental results show that the melting temperature (Tm), crystallization temperature(Tc), melting enthalpy(ΔHm), and crystallinity(Xc) decreased with the increase of PA1012 loading in the copolyamides. The size and number of the copolymers’ spherical crystals decrease by the additions of 1012 units, but its crystalline structure and thermal stabilities does not be affected. The hydrophilicity decreases with increasing PA1012 content from 0 to 28 wt% and the highest contact angle value at the PA1012 loading of 28 wt% is 96°, which can be considered as a surface hydrophobic material. Low temperature (−5 °C)mechanical test results reveal that loss in tensile strength is exchanged for a considerable increase in the strain at break. The impact strength of the PA6-1012 copolyamides is notably enhanced by increasing the PA1012 loading in different test temperatures due to the increase of molecular chain flexibility, indicating that the copolyamindes exhibit enough toughness to suitably apply in low temperature environment.

Emulsion‐based monoliths with a solid‐gel phase‐transition and a solid–solid phase‐transition for latent heat storage

AbstractEmulsion‐based, phase change material‐encapsulated monoliths are promising for latent heat storage. However, such monoliths usually exhibit a solid–liquid phase‐transition and the one‐only phase‐transition might hinder the monoliths for more potential applications. Herein, we report the synthesis of emulsion‐based monoliths with a solid‐gel phase‐transition and a solid–solid phase‐transition for latent heat storage. The solid‐gel phase‐transition was from melting and crystallization of octadecane‐in‐crosslinked poly(octadecyl acrylate) that was formed via radical polymerization of the dispersed phase within oil‐in‐water emulsions, and the solid–solid phase‐transition was from melting and crystallization of the crosslinked polyethylene oxide blocks that were synthesized via the interface‐initiated radical polymerization of the continuous phase. The resulting emulsion‐based monoliths showed negligible mass loss during the heating at 60 °C for 8 h, and exhibited two different crystallization (heat release) temperatures and melting (heat storage) temperatures, corresponding to the solid‐gel transition and the solid–solid transition. Moreover, the monoliths possessed quite high heat density (up to 136.4 J/g), and the heat density did not deteriorate over 20 heating–cooling cycles, showing high reusability. The extremely low leakage, double phase‐transitions and the high reusability make the monoliths to be a good candidate for latent heat storage.

Physico-chemical, sensory and oxidative quality of butter from cows fed 3-nitrooxypropanol

This study aims to investigate the effects of supplementing 3-nitrooxypropanol (3-NOP) to the diet of dairy cows on physico-chemical and sensory properties, as well as oxidative stability of butter. Forty-eight Danish Holstein cows were randomly assigned to control diets or 3-NOP supplemented diets at 60 mg 3-NOP kg−1 feed DM. Compared to control butter, 3-NOP butter had higher proportions of short- and medium-chain fatty acids (FAs) and lower solid fat content, onset crystallization and offset melting temperatures. Sensory analysis revealed minor differences between 3-NOP and control butter, while peroxide values of 3-NOP butter was lower than control butter during storage of 12 weeks. In conclusion, the alterations in FA composition by 3-NOP led to minor changes in physical properties but improved oxidative stability of butter without major changes in sensory characteristics.

Enhancing mechanical and shape memory properties of polylactide/polyamide elastomer blends via reactive blending with a chain extender

AbstractThe structure and properties of incompatible polylactide (PLA)/polyamide elastomer (PAE) blends were tailored by a chain extender specifically the styrene–glycidyl acrylate copolymer Joncryl ADR4368 (ADR). Various PLA/PAE/ADR blends with different compositions were prepared by melt blending, and their morphology, crystallization behavior, and mechanical and the shape memory properties were systematically investigated. The results showed a uniform dispersion of PAE particles in the PLA matrix for the PLA blends with a reduction in particle size upon the addition of ADR. The crystallization of PLA was retarded, which was confirmed by a decrease in the melt crystallization temperature and an increase in cold crystallization temperature in the PLA/PAE/ADR blends. Rheological analysis showed an improvement in the melt elasticity of the PLA/PAE binary blend due to the presence of ADR, possibly attributed to the formation of long‐chain‐branched copolymers at the interface. Notably, the PLA/PAE/ADR blend exhibited superior toughness, featuring an elongation at break of 288% and a notched impact strength of 37 kJ·m−2, along with a high shape memory fixation rate and recovery rate when the ADR content was 1 wt%. Furthermore, the underlying toughening mechanism was elucidated. This work may offer an industrially scalable relevant model to fabricate high‐performance PLA materials.

Predicting melting temperature of inorganic crystals via crystal graph neural network enhanced by transfer learning

The melting temperature, a crucial material property, is particularly challenging to measure accurately for inorganic crystals. The data-driven approach emerges as a potential solution, although its effectiveness is hindered by the limitation of available data. To counter this challenge, we implement transfer learning, leveraging a vast computational database of atomization energy. We first pre-train a geometric-information-enhanced crystal graph neural network (GeoCGNN) using atomization energies of approximately 36,000 materials that are computed by the density functional theory. Subsequently, the pre-trained model is fine-tuned using melting temperatures measured for 799 crystals, encompassing 83 elements, ranging from unary to quaternary systems. This transfer learning strategy decreases the root mean square error from 407 to 218 K, attesting to a marked improvement in prediction accuracy. Furthermore, transfer learning significantly mitigates error variability across unary, binary, and ternary (or higher-order) systems, thereby enhancing the reliability of predictions across a broader range of crystals. We also show that transfer learning allows effective task adaptation by leveraging representation learned from pre-training. Therefore, it can achieve better prediction performance even with a limited number of data for predicting melting points.

Evaluation of maleic anhydride-modified chitosan as filler reinforced PBAT composite film

In this article, maleic anhydride (MA) was used to graft-modify chitosan (CS) to obtain maleic anhydride-modified chitosan (MCS). Composite films with different ratios were prepared by melt blending-extrusion pelletizing-blown film using Poly (butylene adipate-co-terephthalate) (PBAT) as the substrate and CS or MCS as the filler. These films can be utilized in a variety of ways, such as food packaging, agricultural mulching film, and more. The composite films were characterized and tested by a Fourier transform infrared (FTIR) spectrometer, thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), scanning electron microscope (SEM), and electronic universal testing machine, and the effects of different fillers and filler contents on the properties of the composite films were investigated. The results showed that the thermal stability of the composite films decreased slightly with the increase in filler ratio, the melt crystallization temperature increased and then decreased, and the tensile strength and elongation at break of the composite films decreased. Compared with unmodified CS, MCS had better dispersion and compatibility when blended with PBAT, and the interaction between MCS and PBAT was greater than that of CS. The optimal filler amount of MCS was 6% for the combination of film material cost and performance considerations.

Preparation and property evaluation of poly(ε-caprolactone)/polylactic acid/perlite biodegradable composite film

Abstract The feasibility of perlite particles used in poly(ε-caprolactone) (PCL)/poly(lactic acid) (PLA) composite films by melt blending is explored to improve their mechanical property and analyze their antibacterial effect. The effect of perlite content on the mechanical, thermal, hydrophilic, and antibacterial properties of composite films is investigated. Results show that incorporation of 10 wt% perlite in PCL/PLA film improves the tensile strength and hydrophilicity by 1.2 times and 25 %, respectively. After perlite addition, the melting crystallization and glass transition temperature of PCL/PLA film are improved. The presence of perlite also confers antibacterial benefits to the composite film. PLA-based materials are used in the fields of medical materials and food packaging, and their ability to degrade in seawater has been a long-standing goal. In this study, the addition of PCL and perlite not only increases various properties and antibacterial effects, but the blending of inorganic materials and organic materials can destroy the link strength of polymer chain segments of organic materials and help them degrade in seawater. The prepared composite film features broad prospects for the development and application of various fields, such as food packaging and medical materials, reduce white pollution in the ocean.

Impacts of polyketone-grafted carbon nanotube on the thermal, mechanical, and electromagnetic shielding performance of polyketone composites

We report the impacts of polyketone-grafted multiwalled carbon nanotube (CNT-g-PK) on the thermal, mechanical, electrical, and electromagnetic interference (EMI) shielding performance of polyketone (PK) composites. For this purpose, a masterbatch of 10 wt% hydroxylated CNT (CNT-OH) with 90 wt% glycidyl methacrylate-grafted PK (PKGMA) is manufactured by solution mixing and drying. It is then composited with neat PK to fabricate a series of PK/CNT-g-PK composites with varying CNT amounts of 0.5–5.0 wt% via reactive melt-compounding. Infrared spectral results confirm the successful formation of CNT-g-PKs in the melt-compounded composites through the reaction between the hydroxy group of CNT-OH and the epoxy group of PKGMA. Electron microscopic images of PK/CNT-g-PK composites reveal that CNTs are evenly distributed and tightly encapsulated in the composite matrices, indicating good interfacial adhesion between the reinforcing CNT filler and the PK matrix. Accordingly, the melt-crystallization temperature of the PK/CNT-g-PK composites increases as the CNT content increase owing to the nucleating agent role of CNTs, while the melt-crystallization/melting enthalpies decrease due to the mobility hindrance in the PK chains anchored by CNTs. The elastic storage modulus and tensile strength of PK/CNT-g-PK composites are significantly enhanced with increasing CNT content. The 1-mm-thick PK/CNT-g-PK composite with 5.0 wt% CNT exhibits high electrical conductivity of 6.98 × 10−4 S/cm and EMI shielding effectiveness of ∼22.4 dB in the X-band radio frequency range.

Effects of NANH as a nucleation agent on the performance of PLLA

In this research, N,N′-bis(nicotinic) 1,4-naphthalenedicarboxylic acid dihydrazide (NANH) as a new synthetic organic nucleating agent was employed to overcome the slow crystallization rate of poly(L-lactide) (PLLA). Melt crystallization showed that the crystallization ability of PLLA was significantly enhanced by NANH, with NANH still being able to accelerate PLLA crystallization at a cooling rate of 50°C/min. Additionally, when the final melting temperature was 170°C, the onset melt-crystallization temperature and melt-crystallization peak temperature of PLLA/3% NANH were up to 160.0 and 155.1°C, respectively. Isothermal crystallization showed that the half-time of the overall crystallization of PLLA/3% NANH was dramatically reduced, from 71.9 min at 135°C for the virgin PLLA to the minimum value of 0.3 min. This advanced nucleation effect was speculated to be due to chemical nucleation through the theoretical analysis of frontier orbital energy. Melting behaviors under different conditions further confirmed the crystallization-accelerating effect of NANH for PLLA crystallization, and the melting processes were affected by the crystallization temperature and heating rate. Although NANH decreased the thermal decomposition temperature of PLLA in air, the thermal decomposition temperatures of all PLLA/NANH blends were higher than 330°C, which could meet daily usage requirements. Finally, the addition of NANH enhanced PLLA fluidity; however, light transmittance was seriously weakened.

Effects of biomass additives on mechanical strength and water resistance of corn starch straws

To explore a biomass material for significantly improving mechanical strength and water resistance of corn starch straws, lotus root powder, wheat flour and bamboo powder were chosen to study and compare the structure and performances of starch straws. Corn starch straws (CS), corn starch/lotus root powder straws (CSL), corn starch/wheat flour straws (CSW) and corn starch/bamboo powder straws (CSB) were prepared by thermoplastic extrusion. The results showed that CSW had the strongest hydrogen bonding interactions among starch straws. CSW had the largest FTIR 1047/1022 cm−1 ratio and relative crystallinity, indicating the highest degree of short- and long-range order and the highest crystallization melting temperature (298 °C). The relaxation time of all corn starch/additive straws decreased, indicating that stronger chain segment interactions. CSL had the highest flexural strength (81.72 MPa). CSL had the lowest water absorption value after soaked in water at 70 °C, whereas CSW had the lowest water absorption value after soaked in water at 4 and 25 °C. CSL was suitable for hot drinks, while CSW was more suitable for cold drinks. The outcomes would provide a new theoretical basis for selecting the most appropriate additives from biomass materials to interact with corn starch to improve mechanical properties and water resistance of corn starch straws.

Preparation and properties of vermiculite modified by triphenylbutylphosphonium bromide and PBAT composite film

AbstractIn this study, quaternary phosphonium salt (P4) was prepared, vermiculite (VMT) was modified by P4, and P4@VMT/poly (butylene adipate‐co‐terephthalate) (PBAT) composite film was prepared by the solution method. The structure of the synthesized P4 was determined by nuclear magnetic resonance and infrared. The structure and performance of P4 modified vermiculite were explored and analyzed by particle size, XRD, infrared and micro‐morphology. The structure, thermal properties, crystallization properties, rheological properties, cross‐section morphology, tensile properties and antibacterial properties of pure PBAT film and P4@VMT/PBAT composite film were tested and compared. The results show that the crystallization temperature and melting temperature of P4@VMT/PBAT composite film are higher than those of pure PBAT film. With the increase in P4@VMT content, the thermal stability of the composite film becomes worse, and the crystallization enthalpy, melting enthalpy and crystallinity also decrease, while the storage modulus, loss modulus and complex viscosity of P4@VMT/PBAT composite film increase significantly. In addition, compared with pure PBAT film, the tensile strength of P4@VMT/PBAT‐20% composites decreased by 12.0% and the elongation at break decreased by 95.7%.Highlights Successful synthesis of phosphonium quaternary P4 and modification of vermiculite. The properties of P4@VMT/PBAT composite films with different contents were studied.

Impact of organic peroxide on a moderate molecular weight homo-polypropylene vis breaking, and mechanism of interaction

In this study, we show that organic peroxide is a useful tool for breaking the viscosity or chain of polypropylene during melt processing to provide a regulated rheology product. Reactive extrusion is used to crosslink peroxide and combine it with polypropylene (PP). To achieve end-use applications with performance targets, stabilizers are required to preserve the polymer’s initial strength, flexibility, and toughness properties. Other additives are added to PP in addition to stabilization in order to enhance or change certain of its properties. With the addition of varying levels of organic peroxide [2,5-Dimethyl-2,5-di (tert-butyl peroxy) hexane]. The use of peroxide in the manufacturing process of polypropylene is a method of breaking in the polymer chains, which can affect its properties, including its MFI. It is possible that increasing the amount of peroxide used leads to a higher degree of branching or cross-linking, which in turn leads to a higher MFI value. However, it is important to note that the relationship between the amount of peroxide used and the resulting MFI values may not be linear and may depend on other factors as well. In addition to the MFI, other properties of the polypropylene were also measured, including shear and melt flow index, melting and crystallization temperatures, flexural and tensile moduli, and yield stress. These properties are important for understanding the mechanical and thermal behavior of the polymer and can be used to optimize its performance for specific applications.

Extrusion and characterization of recycled polyethylene terephthalate (rPET) filaments compounded with chain extender and impact modifiers for material-extrusion additive manufacturing

The continuous growth of annual production and consumption of polyethylene terephthalate (PET) is coined with increasing waste that leaks into the environment, landfills and oceans as microplastics and nano plastics fragments. Upcycling the recycled PET to make a feedstock for the fast-growing material-extrusion additive manufacturing (MEX-AM) technology can contribute to the solution and supports the concept of sustainable materials. In this work, extrudable filaments comprising recycled polyethylene terephthalate (rPET) with low-cost additives, such as pyromellitic dianhydride (PMDA) as a chain extender, styrene-ethylene-butylene-styrene terpolymer functionalized with maleic anhydride (SEBS-g-MA), a thermal modifier and toughening agent, ethylene-ethyl acrylate-glycidyl methacrylate terpolymer (E-EA-GMA), a functional reactive elastomeric impact modifier and ethylene-ethyl-acrylate (EEA), a non-reactive elastomeric impact modifier, have been fabricated using the twin-screw extruder. The optimum extrusion process parameters for producing uniform filaments of different rPET compounded formulations have been identified, this includes the extrusion die temperature of 280 °C and the screw speed of 150 ± 3 rpm. The compounded filaments are then printed into standard ASTM test specimens for thermal characterization and mechanical characterization, including glass transition and melting temperatures, crystallinity and crystallization temperature, tensile strength, tensile modulus, ductility, flexural strength, and Izod impact energy. Furthermore, the melt flow index for the filaments was measured. More significantly, the experimental data showed that compounding rPET with such additives in the reactive twin-screw extrusion process results in uniform filaments that display advantageous thermal and mechanical properties and can be used as a feedstock in the MEX-AM technology. This study suggests that compounding the recycled PET pellets with low-cost additives while extruding them into filaments for MEX-AM offers excellent potential to make high-value-added customized products from a sustainable polymer feedstock, such as prototyping, tooling, testing components or end-use internal components for small machines and cars.