Melt Flow Index Research Articles

From Waste to Styrene-Butadiene (SBR) Reuse: Developing PP/SBR/SEP Mixtures with Carbon Nanotubes for Antistatic Application.

Styrene-butadiene rubber (SBR) waste from the shoe industry was repurposed to produce polypropylene (PP)-based compounds, with the aim of evaluating their antistatic potential. Styrene-ethylene-propylene (SEP) was added as a compatibilizing agent, while carbon nanotubes (MWCNT) were incorporated as a conductive nanofiller. The polymer compounds were processed in an internal mixer, and injection molded. The properties evaluated included torque rheometry, melt flow index (MFI), impact strength, tensile strength, Shore D hardness, electrical conductivity, heat deflection temperature (HDT), and differential scanning calorimetry (DSC), along with scanning electron microscopy (SEM) for morphology analysis. The production of the PP/SBR/SEP (60/30/10 wt%) compound resulted in a ductile material, enhancing impact strength and elongation at break to 161.2% and 165.2%, respectively, compared to pure PP. The addition of SEP improved the compatibility of the PP/SBR system, leading to an increase in the torque curve and a reduction in the MFI. Furthermore, the SBR/SEP combination in PP accelerated the crystallization process and increased the degree of crystallinity, suggesting a nucleating effect. Carbon nanotubes, in concentrations ranging from 0.5 to 2 phr (parts per hundred resin), were added to the PP/SBR/SEP system. Only the PP/SBR/SEP/MWCNT compound with 2 phr of MWCNT was suitable for antistatic applications, exhibiting an electrical conductivity of 4.52 × 10-07 S/cm. This was due to the greater distribution of MWCNT in the PP matrix, as demonstrated by SEM. In addition, remains tough at room temperature, with a 166% increase in impact strength compared to PP. However, there was a reduction in elastic modulus, tensile strength, Shore D hardness, and HDT due to increased flexibility. SBR waste can be reintegrated into the production chain to produce antistatic polymeric compounds, obtaining a tough material at room temperature.

A rigorous model for hydrogen response in industrial propylene polymerization loop reactors: From micro-mechanism to macro-behavior

In spite of playing a chain transfer agent role, the hydrogen activation effect in propylene polymerization with Ti-based Ziegler-Natta catalysts, so called “hydrogen response”, is usually explained by the dormant-site theory in polymer chemistry. However, how the micro-mechanism at the catalyst site scale affects the macro-behavior of industrial processes is unrevealed. This work aims at developing a rigorous model that can accurately describe hydrogen response and predict polymer chain microstructure for an industrial propylene polymerization process consisting of loop reactors in series. The model is comprised of a kinetic model, a thermodynamic model, and a macroscopic non-ideal loop reactor model. To describe hydrogen response, an elaborated kinetic model is established based on a consistent dormant site reactivation mechanism assuming a multi-site model. The model predictions are in good agreement with plant data, after taking the dormant sites reactivated by hydrogen into account. The proposed model is capable of fully assessing the effects of various process conditions, during steady-state and grade transition processes, on the macro-behavior (i.e., production, slurry density) as well as polymer properties (i.e., melt flow index, molecular weight distribution) in the industrial loop reactors. The underlying correlations are also discussed.

Poly(lactic acid)/poly(vinyl butyral) composites containing kaolin modified by acids and calcination

AbstractThe compatibility between two distinct polymers in the blend is important to maximize various properties of the blends. This study investigated the effects of kaolin modifications through acid and calcination treatments on the compatibility, molecular weight, its distribution, and various properties of poly(lactic acid) (PLA)/poly(vinyl butyral) (PVB) blends. In addition, the incorporation of the modified kaolin as a compatibilizer into the blends enhanced their mechanical and thermal properties, addressing the challenges of immiscibility between distinct polymers. The experimental approach included the utilization of scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, x‐ray diffraction, Fourier transform infrared spectroscopy, rheometer, and melt flow index to examine the structural, molecular, and thermal, mechanical and rheological behaviors of the composites. The changes in various molecular weights were correlated with other properties. The incorporation of surface‐treated kaolin into the blend improved the compatibility between PLA and PVB, exhibiting a singular melting temperature peak and a less distinct interface between two different polymers. This research contributed to the development of sustainable material solutions by demonstrating the potential of modified inorganic fillers in improving the performance of biodegradable polymer blends.

Repetitive recycling effects on mechanical characteristics of poly‐lactic acid and PLA/spent coffee grounds composite used for 3D printing filament

AbstractDue to its biodegradability, biocompatibility, and mechanical properties, poly‐lactic acid (PLA) is a leading biomaterial for numerous applications, especially for fused deposition modeling and fused filament fabrication. Nonetheless, the absence of a comprehensive recycling strategy may emerge as a significant source of plastic pollution in the future. Indeed, the polymer undergoes deterioration during melt recycling, resulting in a decrease in some mechanical properties that can compromise recyclability. To improve the properties of recycled PLA, the utilization of organic fillers coming from renewable materials can be considered as a sustainable solution. The objective of this work is then to evaluate the effect of recycling (reprocessing) on a virgin raw material as well as on biocomposites based on spent coffee grounds (incorporating 5% of spend coffee grounds in weight). The different types of filaments are extruded and re‐extruded and characterized under tensile, melt flow index, and hardness tests. The results show that the increase in the number of extrusions whether for virgin PLA or the composite contributes to the diameter fluctuation. Regarding the tensile properties, the rise in the frequency of recycling shows a weakness in the tensile strength and the elongation at break. On the other hand, Young's modulus values exhibit fluctuations. Concerning the addition of the spent coffee grounds filler, no major enhancement is observed in the tensile strength and the elongation at break, which is attributed to the poor adhesion between the matrix and the filler. The recycling process affects the hardness values of PLA, leading to an increase in these values, as well as those of the composite, which can be associated with the increased crystallinity caused by the recycling process and the SCG incorporation.Highlights Recycling and reusability strategy for poly‐lactic acid (PLA) and PLA/spent coffee grounds (SCG) filaments. Assessment of recycling effects on PLA and PLA/SCG. Mechanical characterization through tensile and hardness testing.

Ultrasound-Assisted Extrusion Compounding of Nano Clay/Polypropylene Nano Compounds.

The incorporation of nanoparticles can significantly enhance the properties of polymers. However, the industrial production of nanocomposites presents a technological challenge in achieving the proper dispersion of nanoparticles within the polymer matrix. In this work, a novel device is presented that can be seamlessly integrated with standard twin-screw extruders, enabling the application of ultrasonic vibration to molten polymeric material. The primary objective of this study is to experimentally validate the effectiveness of this technology in improving the dispersion of nanoparticles. To accomplish this, a comparative analysis was carried out between nanocomposites obtained through conventional compounding extrusion and those processed with the assistance of ultrasonic vibrations. The nanocomposites under investigation consist of a polypropylene (PP) matrix reinforced with nano clays (Cloisite 20A) at a target loading ratio of 5% by weight. To comprehensively evaluate the impact of the ultrasound-assisted compounding, various key properties were assessed, such as the melt flow index (MFI) to characterize the flow behavior, mechanical properties to evaluate the structural performance, oxygen barrier properties to assess potential gas permeability, and microstructure analysis using Scanning Electron Microscopy (SEM) for detailed morphology characterization. The results suggested an improvement in nanoparticle dispersion when using the ultrasound device, particularly when the intensity was adjusted to 60%.

Investigating the Effects of Temperature, Azodicarbonamide, Boron Nitride, and Multilayer Film/Foam Coextrusion on the Properties of a Poly(Hydroxyalkanoate)/Poly(Lactic acid) Blend

AbstractPoly(hydroxyalkanoates) (PHAs) are emerging as sustainable materials in packaging and medical device industries. Nevertheless, the high cost and the need to improve the mechanical properties have limited their widespread use. Blending with other bio-based polymers, such as poly(lactic acid) (PLA), has been proposed in previous studies. This study investigates the effects of temperature, azodicarbonamide (AZ, foaming agent), boron nitride (BN, filler), and multilayer film/foam coextrusion on the properties of a blend containing an amorphous PHA and PLA. The effect of twin-screw micro-compounder temperature (185 °C & 205 °C) and BN concentrations of 1, 2, 3, 5, and 10 wt% (185 °C) on the properties of the PHA/PLA blend were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. Design of experiments (DoE) was used to find the optimal concentrations of AZ and BN (205 °C) using JMP® software. The response surface analysis predicted an optimal design based on the target response levels (modulus, tensile strength, strain at break, and toughness). This formulation was prepared and characterized using DSC, TGA, tensile, and melt flow index (MFI) measurements. Finally, this formulation was processed via film/foam coextrusion and examined using scanning electron microscopy (SEM) and density measurements. This study demonstrated that AZ and BN can be used to manipulate the mechanical properties and crystallinity of PHA/PLA blends, while reducing the overall material cost via density reduction (20–21% for the optimal formulation). Furthermore, reducing the concentration of AZ using the I-optimal design in this study could alleviate the toxicity concerns for food packaging.

Concept for recycling a small-scale plastic-based bioreactor in a close-loop – Technical approach

To accelerate biotherapeutic development whilst decreasing development time and project cost, small-scale multi-parallel bioreactors have been developed to maximize product yield and quality. These systems feature single-use plastic-based bioreactors for easy connection and fast turnaround. Despite well-known advantages, the perception of plastic and the lack of recycling options are raising concerns in the scientific laboratories’ community. One of the common objections to plastic circularity in life-science is the perceived “downcycling” effect of mechanical recycling. Therefore, the aim of this work was to establish the technical feasibility of a close-loop recycling concept for the main construction material of the small-scale bioreactor. Application tests (cell compatibility and cell culture) were performed and supported by quantitative physical and mechanical tests (tensile, melt flow index, light transmission). Results show that mechanically recycled polycarbonate could be re-used in the same application. A comparative life cycle assessment (LCA), based on a theoretical framework, showed with different scenarios that recycling would have a positive impact on Climate – Carbon – total within the boundaries. Even if the technical feasibility of such a concept is demonstrated through this study, several challenges remain for such a closed-loop recycling concept to be implemented at a commercial scale.

Toward the production of bioblends for the automotive sector: Reuse of recycled polyamide 6,6 to prepare super‐tough biopolyethylene

AbstractPlastics reuse is essential for promoting a sustainable future, especially by mitigating environmental impacts. Recycled polyamide 66 (PA66r) was reused for the produce biopolyethylene (BioPE)‐based blends, aiming to obtain a super‐tough material. Initially, a premix of PA66r with maleic anhydride‐grafted ethylene–propylene–diene (EPDM‐MA) was obtained in an internal mixer. Subsequently, the BioPE/PA66r and BioPE/(PA66r/EPDM‐MA) blends were processed in a twin‐screw extruder and injection molded. The rheological, mechanical, thermal, thermomechanical, structural, and morphological properties were investigated. Torque rheometry indicated an increase in the viscosity of the BioPE/(PA66r/EPDM‐MA) blends compared to BioPE/PA66r, which was confirmed by a reduction in the melt flow index (MFI). EPDM‐MA promoted greater stability in BioPE/(PA66r/EPDM‐MA) blends during processing, reducing the degradation rate and molecular weight loss. The BioPE/(PA66r/EPDM‐MA) blend with the 70/(15/15)% composition exhibited super‐tough behavior, with 822.4 J/m impact strength and 233% elongation at break. Scanning electron microscopy indicated a fracture with high plastic deformation, elongated fibrils, and refined particles (0.64 μm), confirming the high toughness. Apparently, a core‐shell morphology was formed, which favored maintaining tensile strength, Shore D hardness, and heat deflection temperature comparable to pure BioPE. The results indicate potential for application in the automotive industry, contributing to reintroducing recycled material into the production chain.

Injection molding of post-industrial recycled glass fiber reinforced polyphenylene sulfide (PPS GF40): industrial feasibility and material analysis

Polymer recycling has become increasingly important in recent decades due to economic and environmental benefits. Recycling provides a cost-saving material supply as well as avoids environmental spillage and enables resource conservation. Quantifying the changes in material properties due to recycling is a key aspect in establishing a circular economy, as it allows understanding the impact of using recycled materials on manufacturing and products. To date, research and industry have investigated the use of recycled materials for commodity and engineering polymers. For high performance plastics, this knowledge exists only at the laboratory scale. The present study comprehensively characterizes the properties of virgin and recycled glass fiber reinforced polyphenylene sulfide (PPS GF40) materials. The materials considered are commercially available to industry, and the recyclates have been reclaimed from post-industrial wastes by the material manufacturers. The results show that as the recycled content increases, the tensile strength of PPS GF40 revealed a similar value for a 50 % recyclate or decreases by 21 % for a regranulate due to both macromolecular shortening and fiber scission. In addition, the shrinkage of each material is quantified. Here, shrinkage increases with increasing result of recycled content. Increasing the amount of recycled material in the compound results in lower process forces in injection molding due to higher melt flow indices. With the help of these results, industrial products may be tailored to meet the properties of recyclate-based materials in order to conserve virgin material resources. In addition, material cost saving potentials are identified by economic calculations based on presently available industrial offers. In the light of the presented results, the introduction of recyclate-based PPS GF40 materials into industrial mass production can be assessed on the basis of mechanical and rheological properties as well as material costs. The overall objective of this study is to provide the aforementioned insights to exploit the economic and environmental benefits of polymer recycling on an industrial scale.

Parameter Optimization in FDM Filament Fabrication via Single Screw Extruder

The presence of polymer material filaments plays a crucial role in the realm of 3D printing. These filaments are utilized in 3D printing to create prototype products efficiently and cost-effectively. However, ensuring the production of high-quality prototype products necessitates the use of superior filaments characterized by consistent diameter and a round cross-section. Filaments are typically manufactured through an extrusion process using either a single screw extruder or a twin extruder. In this research, a DIY single-screw extruder was developed specifically for filament production. The main objective of this study is to generate quality filaments by optimizing the extruder parameters for various polymer materials. Three different polymers; Ethylene-vinyl Acetate (EVA), Polypropylene (PP), and Acrylonitrile Butadiene Styrene (ABS) were employed in this study. The research aimed to assess the melt flow index (MFI) to demonstrate viscous behavior and establish the ideal parameters for each material in the extrusion process. A total of 27 EVA material filament samples, 26 PP filament samples, and 26 ABS filament samples were successfully produced. Through analysis, optimal settings were identified for EVA, PP, and ABS filaments, resulting in high-quality production. The recommended parameters for producing quality EVA filaments included a temperature of 160°C, screw speed of 400 rpm, and take-up speed of 400 rpm. For PP filaments, the optimal settings comprised a temperature of 230°C, screw speed of 700 rpm, and take-up speed of 250 rpm. Lastly, ABS filament production was optimized with a temperature of 210°C, screw speed of 300 rpm, and take-up speed of 100 rpm. This project's outcomes are anticipated to have significant implications for future advancements in filament manufacturing processes.

Mono-axial stretching-induced growth of crystalline phase of melt-processed perfluoroalkoxy alkane (PFA) films for protecting inner layer of battery pouch films

Cast polypropylene (CPP) is employed as an inner layer of pouch films; however, CPP shows poor electrolyte, mechanical, and electrical stability, which can lead to instability during cell operation. In this study, we pioneered the use of perfluoroalkoxy alkanes (PFA) in the melt extrusion process to fabricate films based on their high melting flow index, establishing optimal conditions for producing uniform films. We further enhanced the functionality of these films by controlling the crystalline phase orientation through high-temperature uniaxial stretching, which is aimed at applications in battery pouch films. The stretched PFA films exhibited dramatically improved mechanical and insulation properties compared to traditional CPP films, 307.4% increase in tensile strength and 1,748.8% increase in breakdown strength, respectively. Based on these findings, we proposed that stretched PFA films, with their superior performance, are viable substitutes for CPP as the inner layer in battery pouch films. This research not only advances the material science of polymer films but also contributes to the development of safer and more efficient battery technologies.

Potential of caffeic acid as an effective natural antioxidant for polypropylene-polyethylene copolymers: A DFT and experimental study

Caffeic acid (CAF) i is a polyphenolic compound commonly found in plants, valued for its ability to act as an antioxidant. This study focused on investigating the impact of a natural antioxidant, specifically caffeic acid (CAF), compared to two synthetic antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), on the thermal stability of propylene/ethylene copolymer (C-PP/PE), Aiming to establish a theoretical framework for the advancement of novel polymeric antioxidant compounds. Theoretical calculations were conducted to determine each compound's thermodynamic properties and antioxidant activity. The phenolic hydroxyl bond dissociation enthalpy (BDE) values revealed that BHA had the lowest value (325.6 kJ mol−1), trailed by CAF (328.2 kJ mol−1) and BHT (341.3 kJ mol−1), indicating a higher electron-donating capacity of BHA. Transition energy (TS) calculations indicated that BHA had the lowest TS energy (49.29 kJ mol−1), succeeded by CAF (57.61 kJ mol−1) and then BHT (75.57 kJ mol−1), suggesting greater efficiency in radical scavenging. Additionally, the obtained rate constants showed that CAF had the highest hydrogen abstraction rate (k = 1.05 × 10⁵ M⁻1 s⁻1), followed by BHA (k = 1.17 × 10⁴ M⁻1 s⁻1), and then BHT (k = 4.2 × 10³ M⁻1 s⁻1). These results support the effectiveness of CAF as a potentially more active antioxidant. In the experimental part of this study, it was observed that C-PP/PE with BHA showed a lower melt flow index (MFI) (8.51), indicating more excellent thermal stability. On the other hand, samples containing natural caffeic acid extracts exhibited a gradual decrease in MFI with increasing CAF concentration (MFI of 9.4, 8.82, 7.59, 6.44, and 5.98 for concentrations of 0.025, 0.05, 0.075, 0.1, and 0.125 ppm, respectively), suggesting a progressive improvement in the thermal stability of C-PP/PE with increasing natural antioxidant. In TGA analyses, decomposition was observed around 340 °C in samples without additives and those containing 0.1 ppm of BHA. In contrast, samples with different concentrations of CAF showed delayed degradation, observed in the temperature range of 380–400 °C. This delay in degradation indicates that CAF imparts more excellent thermal stability to C-PP/PE copolymer, as it reaches temperatures above 400 °C before starting its decomposition. These findings support the feasibility of using natural antioxidants such as CAF to improve the thermal properties of copolymers.

Synthesis, Characterization, and Evaluation of a Hindered Phenol-Linked Benzophenone Hybrid Compound as a Potential Polymer Anti-Aging Agent.

Hindered phenol antioxidants and benzophenone UV absorbers are common polymer additives and often used in combination applications to enhance the anti-aging performance of polymer materials. This study primarily aims to incorporate hindered phenol and benzophenone structures into a single molecule to develop a multifunctional polymer additive with good anti-aging performance. Thus, a novel potential polymer anti-aging agent, namely 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid 3-(4-benzoyl-3-hydroxyphenoxy)propyl ester (3C), was synthesized using 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 3-bromo-1-propanol, and 2,4-dihydroxybenzophenone as raw materials by two-step procedure. The structure of compound 3C was characterized by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray single crystal diffraction. Its thermal stability and UV resistance were assessed using thermogravimetric analysis (TGA) and UV absorption spectroscopy (UV). The compound 3C as an additive was incorporated into the preparation of polyolefin elastomer (POE) films. The anti-aging performance of POE films was evaluated by measuring parameters such as oxidation induction time, melt flow index, transmittance, and infrared spectra of the artificially aged POE films. The results indicate that the compound 3C exhibits a promising anti-aging performance in both thermo-oxidative aging and ultraviolet aging tests of POE films and is a potential polymer anti-aging agent.

Impact of Different Mineral Reinforcements on HDPE Composites: Effects of Melt Flow Index and Particle Size on Physical and Mechanical Properties.

The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

Fabrication, characterization and evaluating properties of 3D printed PLA-Mn scaffolds

Polylactic acid (PLA) based scaffolds have attained considerable attention in recent years for being used as biodegradable implants in bone tissue engineering (BTE), owing to their suitable biocompatibility and processability. Nevertheless, the mechanical properties, bioactivity and biodegradation rate of PLA need to be improved for practical application. In this investigation, PLA-xMn composite filaments (x = 0, 1, 3, 5 and 7 wt%) were fabricated, characterized, and used for 3D printing of scaffolds by the fused deposition modeling process. The effect of Mn addition on the thermal, physical, mechanical, and structural properties, as well as the degradability and cell viability of 3D printed scaffolds were investigated in details. The obtained results indicate that the PLA-Mn composite filaments exhibit higher chain mobility and melt flow index values, with lower cold crystallization temperature and a higher degree of crystallinity. This higher flowability led to lower dimensional accuracy of 3D printed scaffolds, but resulted in higher interlayer adhesion. It was found that the mechanical properties of composite scaffolds were remarkably enhanced with the addition of Mn particles. The incorporation of Mn particles also caused higher surface roughness and hydrophilicity, a superior biodegradation rate of the scaffolds as well as better biocompatibility, indicating a promising candidate for (BTE) applications.

Improving Environmental Stress Cracking Resistance of High-Density Polyethylene Grades by Comonomer Addition and Nanocomposite Approach.

The aim of this paper is to determine the effect of polymer density, correlated to the comonomer content, and nanosilica addition on the mechanical and Environmental Stress Cracking Resistance (ESCR) characteristics of high-density polyethylene (HDPE). In this regard, five HDPE samples with similar Melt Flow Index (MFI) and molar mass but various densities were acquired from a petrochemical plant. Two polymerization reactors work in series and differ only in the amount of 1-buene comonomer fed to the second reactor. To ascertain the microstructure of the studied samples, GPC and SSA (successive self-nucleation and annealing) analyses were accomplished. All samples resulted having similar characteristics but slightly various SCB/1000 C=7.26-9.74 (SCB=Short Chain Branching). Consequently, meanwhile studied HDPEs reveal similar notched impact and stress at yield values, the tensile modulus, stress-at-break, and elongation-at-break tend to demonstrate different results with the SCB content. More significantly, ESCR characteristic varied considerably with SCB/1000 C extent, so that higher amount of SCB acknowledged advanced ESCR. Notably, blending HDPE sample containing higher amount of SCB/1000 C, with 3 wt.% of chemically modified nanosilica enhanced ESCR characteristic by 40 %. DFT (Density Functional Theory) calculations unveiled the role of the comonomer, quantitatively by binding energies and qualitatively by Non Covalent Interaction (NCI) plots.

Optimization of physical and mechanical properties of PC/ABS/PMMA blends by mixture design approach

AbstractThis study aims to investigate the recycling of end‐of‐life computer plastics, focusing on polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) copolymer, which constitute a significant portion of collected computers. Through differential scanning calorimetry and infrared spectroscopy analyses, the properties of raw PC, ABS and poly(methyl methacrylate) (PMMA) were evaluated. Various blends of PC and ABS were prepared, incorporating different percentages of recycled PMMA as a cost‐effective coupling agent. These blends were processed through melt compounding using a contra‐rotating twin‐screw extruder and subsequently shaped by injection molding. An experimental mixture design was applied to evaluate the mechanical and physical properties of the composite materials, including melt flow index, hardness, flexural strain at break and Charpy impact strength. The results of the desirability analysis indicated that the optimal blend for achieving a balance between mechanical and physical properties consists of a high PC content (approximately 80% or more), a low ABS content (less than 20%) and less than 5% recycled PMMA. © 2024 Society of Chemical Industry.

Investigations into 4D printed PLA/graphite composite with thermal induced shape memory effect

PurposeThe paper aims to fabricate shape memory composites using polylactic acid (PLA) matrix and graphite. Shape memory polymers are a promising family of materials for biomedical applications because of their favourable mechanical properties, fast reactions and good biocompatibility. For most SMPs, however, achieving controllable sequential shape change is challenging.Design/methodology/approachIn the present work, 4D printing technology is used to fabricate shape memory composites using polylactic acid (PLA) matrix and graphite. A comparative study of pure PLA and graphite’s different weight % composition has been done.FindingsBy carefully managing the deformation state, PLA with graphite shape memory composites produced controllable sequential deformation with an amazing shape memory effect. Surface morphology, thermal properties, melt flow index and shape recovery tests have all been carried out to assess the qualities of manufactured samples.Originality/valueThis is a one-of-a-kind to fabricate shape memory composites using graphite and a PLA matrix. Thus, this research attempts to deliver the possible use of PLA/graphite composites fabricated using 4D printing in robotics and biomedical devices.Graphical

Silane-modified high-yield lignocellulosic fibers as reinforcement of polylactic acid: Enhancement of interfacial adhesion for high-performance biocomposites

This study investigates the enhancement of PLA-based biocomposites using high-yield mechanical stone groundwood (SGW) pulp, with a focus on reinforcing fiber-matrix interactions through silane-coupling fiber modification. Different fractions of SGW (20 and 30 wt%) and (3-glycidyloxypropyl)trimethoxysilane (GPS) as a coupling agent (3, 5, 7, and 10 wt%) were incorporated into the PLA matrix. Thermo-mechanical properties including melt flow index, melt rheology, tensile strength, and Young’s modulus were evaluated, along with thermal degradation behavior via TGA and DSC. Non-modified and partially modified SGW fractions (20 and 30 wt%) improved PLA-SGW interface, resulting in increased tensile strength (14 % and 27 % respectively). Biocomposites with 30 wt% SGW modified with 5 and 7 wt% GPS exhibited the highest tensile strength improvement, along with the rest of the properties, attributed to GPS influence on melt flow index and processability. The obtained biocomposites showcased properties comparable to commodity polypropylene composites.

Fabrication and development of high temperature resisted bronze composites using 3D printed gate pattern through stir casting route

Fused deposition modeling (Additive manufacturing method) is used for printing the gate pattern by considering Acrylonitrile butadiene styrene (ABS), alumina (Al2O3), and silicon carbide (SiC) as raw material. The three compositions of feedstock filaments are ABS −2% Al2O3 − 0. wt % SiC, ABS −2% Al2O3 − 3. wt % SiC and ABS −2% Al2O3 − 6. wt % SiC, which are produced by using melt flow extruder. The melt flow index of three compositions are determined as 2.413 /10 min, 2.403/10 min and 2.389/10 min which are near to ABS melt flow index of 2.44 / 10 min. The gate pattern is prepared by fusion deposition modeling method by considering parameters such as SiC reinforcement (wt %), raster inclination and infill density and best optimal parameter for producing pattern comprising high tensile strength and high flexural strength using Technique Order Preference Similar to Ideal Solution (TOPSIS). The best set of optimal parameter for printing the gate pattern was found out as ABS −2% Al2O3 −6 wt% SiC, infill density of 50 % and raster inclination 0°. This pattern exhibited average surface roughness of 12.6 µm, tensile strength of 40.5 MPa and flexural strength of 73.1 MPa. The lowest tensile strength of 29.3 MPa was observed for 3 % SiC, 50 % infill density and 30° raster orientation. Using the printed gated pattern via stir casting process, four different compositions of bronze composites are synthesized such as Cu-Sn- 0 wt% B4C, Cu-Sn- 2 wt% B4C, Cu-Sn- 4 wt% B4C and Cu-Sn- 6 wt% B4C. Cu-Sn- 2 wt% B4C composite exhibited maximum hardness, tensile strength and impact strength of 55 HRC, 323 MPa and 279 N/mm2 respectively. The lowest tensile strength, lowest hardness and maximum deviation in dimension of 323 MPa, 38 HRC and 0.144 mm was found out for Cu-Sn-6 wt% B4C. The best optimized pattern: ABS −2% Al2O3 −6 wt% SiC, infill density of 50 % and raster inclination 0° was used as a pattern for producing seven casted cubes (Cu-Sn-2 wt% B4C) which shows average dimension of ± 0.12 mm.