Thermoplastic Materials Research Articles

Modelling the time-dependent mechanical properties of thermoplastic and thermosetting polymers with Gumbel distribution functions

In this paper, we propose a simple modelling method that accurately describes the time-dependent viscoelastic behaviour of thermoplastic and thermosetting solid polymers. We performed short-term creep and stress relaxation tests on representative samples of three major classes of polymers: an amorphous, a semi-crystalline thermoplastic and a thermosetting polymer. Then, to investigate the relationship between the model parameters and the material composition, we also tested thermoplastic matrix composites with different plasticiser contents. From the short-term tests, master curves were constructed with the use of the time–temperature superposition principle. Then, the temperature dependence of the obtained shift factors was described using the Arrhenius model. The resulting creep compliance and relaxation modulus master curves were normalised and modelled with a two-parameter cumulative Gumbel distribution function (CDF) and its complementary distribution function (CCDF). For the creep and stress relaxation master curves, the median error of modelling was less than 16 % and 16.5 % in all cases, respectively. Furthermore, it was less than 2 % for the thermosetting polymer, making this model an excellent tool for describing the creep and stress relaxation behaviour of thermosetting systems. In the case of the plasticised composites, we found a strong relationship between the material composition and the location parameter of the Gumbel model. Based on this, we developed a method that can be used to estimate the evolution of the creep compliance curve for any arbitrary OLA content (between 0 wt% and 16 wt%) at any desired temperature (between 22 °C and 70 °C).

Nanodiamond Nano-Reinforcements in Thermoplastic (Polyamide, Polyimide, Polystyrene) Nanocomposites—Essential Characteristics and Technicalities

Nanodiamonds are unique spherical carbon nano-entities having the advantages of very high surface area and high optical, thermal, wear and strength characteristics. Like other carbonaceous nanoparticles (like fullerene, graphene or carbon nanotube), nanodiamond nano-reinforcements have been investigated for the significant types of polymeric matrices (such as thermosets, thermoplastics, rubbers) nanocomposites. Consequently, this overview was planned to systematically describe the current scientific status of the nanodiamonds reinforced thermoplastic nanomaterials. In this regard, polyamide/nanodiamonds, polyimide/nanodiamonds and polystyrene/nanodiamonds nanocomposites have been fabricated using the facile solution, in-situ and melt mixing techniques. We suggest that including nanodiamonds in polyamides and polyimides increased their engineering characteristics, like mechanical properties and thermal stability, of the resulting nanocomposites due to a distinct interface formation and their compatibilization effects toward these matrices. Correspondingly, including nanodiamonds in polystyrene has been observed to increase the intrinsically low strength/toughness features of this polymer. Predominantly, nano-reinforcement and miscibility effects of the nanodiamonds with the polystyrene and their mutual matrix-nanofiller synergies were responsible to improve the overall microstructural and physical properties of the resulting nanocomposites. As per our analysis, the research reports so far on the important categories of the nanodiamonds reinforced thermoplastic matrix nanocomposites have shown important technical applications in the fields of high-tech coatings, membranes and energy devices.

Material Selection and Design for Assembly Applied in the Development of an Energy Generating Device

This study used the Design for Assembly (DFA) and material selection methods as tools to aid the development of a conceptual design of a functional device to transform alternate movement into rotational movement on the axis of a microgenerator. Also, material selection software was used to define the most suitable thermoplastic materials for some components of the projected device, focusing both on performance and low cost. There was a considerable reduction in the number of parts in the set from the basic device (prototype), which had 47 parts, to the conceptual design I, with 34 parts, and the conceptual design II, with 14 parts. The total mass of the set was also considerably reduced, from 160 grams for the basic device to 57.01 grams in the conceptual design I and, finally, 18.30 grams in the conceptual design II. Of thermoplastic materials analysed, considering a selection focused only on performance the most promising candidate, with an ideal set of properties is PEEK. But for a selection that considers the price, that is one of the key variables in the materials selection for most products, PEEK shows is prohibitively price.

Fracture behavior of 3D-printed thermoplastics—A dilemma of fracture toughness versus fracture energy

The Material Extrusion (ME) technique in 3D printing facilitates the production of thermoplastic materials with diverse cellular or lattice-like infill geometries, enabling the creation of lightweight, high-performance materials. This study investigates the influence of infill geometry and relative density on the fracture behavior of 3D-printed thermoplastics produced through ME. Polylactic acid (PLA) is used as the model material, with unit cell geometries-square, triangle, and Kagome-and relative densities ranging from 0.4 to 0.8 explored. Tensile tests are first conducted to determine in-plane elastic moduli in two orthogonal directions, accounting for unit cell anisotropy. These results are employed in effective fracture energy calculations. Compact tension fracture tests follow, quantitatively characterize crack growth characteristics in both directions. In both tests, digital image correlation method is used to measure full field strain distributions. Three significant findings emerge. First, there is a power scaling relationship between Elastic Modulus and relative density across all unit cells, with Kagome exhibiting the highest correlation constant. Triangle and Kagome unit cells show negligible orthotropic responses in perpendicular directions for varying relative densities. Second, the relationship between nondimensional fracture toughness and relative density follows a similar scaling law, with minor variations depending on unit cell type. The correlation factor slightly dependens on unit cell geometry but remains around 3 across the the examined relative density range. Third, considering the dissipation of inelastic fracture energy, both triangle and Kagome unit cell geometries demonstrate an order of magnitude higher effective fracture energy (i.e., crack growth resistance) compared to the square unit cell. This is associated with toughening mechanisms such as crack deflection and bifurcation. These findings highlight the disparity between fracture toughness and effective fracture energy in assessing the fracture resistance of 3D-printed thermoplastics, clearly demonstrating that fracture toughness alone is insufficient for a comprehensive assessment. The proposed scaling laws provide predictive insights into the fracture toughness of polymeric materials produced via the ME method.

A scanning electron microscope evaluation of surface roughness of different clear aligners – A comparative in-Vitro study

Clear aligner are thermoplastic polyurethane materials which produces small increments of tooth movements by each aligner tray. Clinical effectiveness of the treatment largely depend on the mechanical properties of the material. The use of scanning electron microscopy (SEM) in invitro environment allows to evaluate the surface morphology of the aligners The aim of the study is to compare the surface roughness of different types of clear aligners after thermoforming and after invitro aging. A sample of 15 aligners from Group A (DURAN), Group B (ERKODUR), Group C (MONOFLEX) were taken for this study. After screening the subjects were scanned by intraoral scanner and STL file were imported to Maestero 3D software. Then resin models were printed and aligners were fabricated in the models by thermoforming machine. The first set of aligners were scanned by Scanning Electron Microscope and another set of aligners were placed in chewing simulator for simulating intraoral environment. Then the second set of aligners were sent for SEM evaluation. Mean comparison of surface roughness and root mean square surface roughness was compared by paired t test and comparison among the groups was done by one way ANOVA test. The surface roughness of both aligners increased after thermoforming. This could be due to thermoforming process which could be due to temperature variation. After the ageing of the aligners in the invitro environment, there is homogenous and smooth layer of the aligner surfaces which could be due to adhesion of biofilm and polishing effect by chewing strokes.

Experimental investigation on low‐velocity impact performance of carbon fiber reinforced polyether ether ketone thermoplastic composite materials in room and elevated temperature

AbstractCarbon fibers woven‐ply reinforced polyether ether ketone (C/PEEK) thermoplastic composites are widely used in aerospace and high‐tech industries because of their exceptional resistance to low‐velocity impact. In this paper, experimental investigation is carried out to determine the low‐velocity impact performance of C/PEEK laminates at room temperature (RT) and high temperature (90°C and 150°C) environments. Both macroscopic and microscopic analyses are applied to examine the influence of temperature on the mechanical response and damage mode of the material. The attention of this investigation is on impact parameters such as maximum contact force, energy absorption rate, indentation depth, and damage mode. The findings show significant changes in material stiffness, rate of energy absorption, and indentation depth with rising temperature. Temperature variations have a notable effect on the PEEK matrix plasticity, C/PEEK composite interlaminar properties, crack initiation and propagation, and damage mode at the overlaps of warp and weft fibers, resulting in a transition from brittle to ductile failure.Highlights Experimental investigation is carried out to study the low‐velocity impact performance of C/PEEK. The effects of impact energy and environmental temperature on the low‐velocity impact performance of C/PEEK are investigated. The mechanism of how environmental temperature affects the damage mode of C/PEEK is investigated.

Fabrication of a 3D Printer Filamnet Extruder

3D printing, an additive manufacturing process, transforms digital designs into physical objects by layering material. This mechanization adds consecutive layers to build up the complete entity, resulting in a 3D object. It develops objects progressively to formulate the preferred look. Filaments are the main component in a die cast model (FDM) 3D printer, these are thermoplastic substances that are injected through a hot die to form the object. These filaments are available in different types such as PLA, ABS, PETG, HDPE each of which has specific characteristics that offer different applications and material options in 3D printing. This paper depicts about fabricating and developing a design of a 3D filament extruder that can produce 1.75 mm diameter filaments from recycled HDPE material. The extruder consists of a motor, a speed controller, a cylinder, a hopper, band heaters, a thermocouple, a temperature controller, a fan, a nozzle and a winder. This system works in the correct temperature range of 350-370 degrees Celsius for melting thermoplastic materials (recycled HDPE). Extruder function is to feed the material from the nozzle into the hot cylinder. A motor screw pushes the metal into the nozzle, where it becomes the filament. This filament is then injected onto a substrate for later use in 3D printing. The temperature is determined using thermocouples and a temperature controller, which ensures optimal extraction conditions. A fan is designed to quickly cool the removed filament. The objective of this research is to create an economical as well as efficient filament to produce high quality filaments. Extruder performance is evaluated based on filament diameter consistency, material penetration and energy efficiency.

Evaluation of Mechanical Properties of Composite Material with a Thermoplastic Matrix Reinforced with Cellulose Acetate Microfibers.

Low-density polyethylene (LDPE) has been widely used in various applications due to its flexibility, lightness, and low production cost. However, its massive use in disposable products has raised environmental concerns, prompting the search for more sustainable alternatives. This study aims to investigate the mechanical properties achievable in a composite material utilizing low-density polyethylene (LDPE), potato starch (PS), and cellulose microfibrils (MFCA) at loadings of 0.05%, 0.15%, and 0.30%. Initially, the cellulose acetate microfibrils (MFCA) were produced via an electrospinning process. Subsequently, a dispersive mixture of the aforementioned materials was created through the extrusion and pelletizing process to form pellets. These pellets were then molded by injection molding to produce test specimens in accordance with ASTM D 638, the standard for tensile strength testing. The evaluation of the properties was conducted through mechanical tensile tests (ASTM D638), hardness tests (ASTM D 2240), melt flow index (ASTM D1238), and scanning electron microscopy (SEM). This study determined the influence of cellulose acetate microfibril loadings below 0.3% as reinforcement within a thermoplastic LDPE matrix. It was demonstrated that these microfibrils, due to their length-to-diameter ratio, contribute to an enhancement in the mechanical properties.

Experimental and numerical analysis of new thermoplastic composite mandrels

In the field of aerospace, the application of carbon fiber composite parts is increasing year by year. As an important factor in the manufacturing of composite parts, tools play a crucial role in the manufacturing accuracy of composite parts, and composite tools have higher accuracy to better meet the manufacturing requirements. In this study, the properties of the novel thermoplastic composite mandrel of the new polymethyl methacrylate matrix are further investigated and a model is proposed to simulate the curing and spring back process of the composite part with the proposed composite mandrel. In detail, the glass transition temperature test and dynamic frequency test were carried out for the thermoplastic composite mandrel. The material constitutive equation of the thermoplastic composite mandrel was constructed based on the experimental data, and the accuracy of the constitutive equation of thermoplastic matrix material was verified by tensile experiments of matrix materials under constant strain conditions. Finally, the simulation result is compared with the fabricated part, and the effectiveness of the proposed method has been verified. This proved that the developed constitutive model of thermoplastic composite mandrel can effectively predict the curing deformation of composite parts with complex structures.

Characterisation of 3D-printable thermoplastics to be used as tissue-equivalent materials in photon and proton beam radiotherapy end-to-end quality assurance devices

Objective. To investigate the potential of 3D-printable thermoplastics as tissue-equivalent materials to be used in multimodal radiotherapy end-to-end quality assurance (QA) devices. Approach. Six thermoplastics were investigated: Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), Polyethylene Terephthalate Glycol (PETG), Polymethyl Methacrylate (PMMA), High Impact Polystyrene (HIPS) and StoneFil. Measurements of mass density ( ρ ), Relative Electron Density (RED), in a nominal 6 MV photon beam, and Relative Stopping Power (RSP), in a 210 MeV proton pencil-beam, were performed. Average Hounsfield Units (HU) were derived from CTs acquired with two independent scanners. The calibration curves of both scanners were used to predict average ρ, RED and RSP values and compared against the experimental data. Finally, measured data of ρ, RED and RSP was compared against theoretical values estimated for the thermoplastic materials and biological tissues. Main results. Overall, good ρ and RSP CT predictions were made; only PMMA and PETG showed differences >5%. The differences between experimental and CT predicted RED values were also <5% for PLA, ABS, PETG and PMMA; for HIPS and StoneFil higher differences were found (6.94% and 9.42/15.34%, respectively). Small HU variations were obtained in the CTs for all materials indicating good uniform density distribution in the samples production. ABS, PLA, PETG and PMMA showed potential equivalency for a variety of soft tissues (adipose tissue, skeletal muscle, brain and lung tissues, differences within 0.19%–8.35% for all properties). StoneFil was the closest substitute to bone, but differences were >10%. Theoretical calculations of all properties agreed with experimental values within 5% difference for most thermoplastics. Significance. Several 3D-printed thermoplastics were promising tissue-equivalent materials to be used in devices for end-to-end multimodal radiotherapy QA and may not require corrections in treatment planning systems’ dose calculations. Theoretical calculations showed promise in identifying thermoplastics matching target biological tissues before experiments are performed.

Comparison of single- and hybrid-fiber composite laminates for use in prosthetic sockets

Traditional prosthetic sockets often consist of thermoplastic and wood-based materials. However, these sockets are known to be uncomfortable, heavy, and economically challenging. Natural fibers are quickly adapting and becoming more popular because of their biodegradable, long-lasting, and biocompatible nature. They are replacing synthetic fibers in the design and development of structural parts. This research looked into a new hybrid composite made of natural and synthetic fibers (basalt, jute, and carbon) that are reinforced in a polyester thermoset based matrix. The performance of this hybrid composite was then compared to that of pristine or single fiber-reinforced composites manufactured using woven jute, basalt, and carbon. The samples were manufactured using the vacuum-assisted resin transfer molding technique and cured at room temperature. The samples were then subjected to flexure and impact tests. The hybrid composite had an impact strength of 46.71 kJ/m2, higher than all other single fiber combinations. The flexural strength of the hybrid composite was determined to be 66.25 MPa, matching that of basalt fiber and surpassing that of other conventional single fiber composite laminates. Fractographic analysis has revealed that the main cause of failure in flexure is mostly attributed to delamination and fiber micro-buckling. Although hybrid reinforced composites had superior performance in terms of both impact and flexure strength, basalt fibers demonstrated comparable strength, specifically in flexure. Overall, the hybrid composite possesses exceptional promise for use in prosthetic construction.

Design of Mold Flipper in an Effort to Improve The Efficiency of Mold Maintenance Process

Molding is a production process by forming raw materials using a rigid frame or model used in the manufacturing industry to mold materials called a mold. Injection molding is a technique in the manufacturing industry for molding thermoplastic materials. Thermoplasctic materials commonly molded with Injection Molding techniques are Polystyrene, Acrylonitrile Butadiene Styrene (ABS), PMMA (Polymethyl Methacrylatic) and others. The purpose of this research is to design and build a flipper molding tool for an easier and more efficient mold maintenance process. This research uses descriptive methods. Data is taken through direct observation and through reference books both from companies and websites and journals related to the report material. The data obtained was analyzed using descriptive analysis. it is found that the material used in the work is Carbon Steel (S45C). The process of making Flipper Clamps Mold has several stages, namely the Design Making Process, Material Selection Process, Cutting Process, Milling Process, Grinding Process, Drilling Process, Welding Process, and Assembly Process. With this Flipper Clamping tool, it is hoped that it can make it easier for operators to maintain and repair molds, because the previous mechanism requires two operators to flip molds that weigh more than 200 kg, now they only need to flip by turning the lever of this tool.

Three-dimensional computational fluid-dynamic simulation of polypropylene steam gasification

Among the recycling techniques, gasification allows to obtain a hydrogen-rich gas from polypropylene (PP), a widely used thermoplastic material. In this work, devolatilization and steam gasification tests of PP were conducted in fluidized bed reactors. The results show a gas yield of 1.3 and 3.0 Nm3/kgPP, and a tar content of 117.3 and 20.9 g/Nm3 from devolatilization and gasification, respectively. Experimental results provide an overall overview of this process, able to produce a syngas with an H2-content of 50 vol%dry.Experimental data coupled with kinetic analysis were used to develop a computational fluid dynamic model (CFD) capable of describing both thermal degradation and subsequent gasification reactions. Although some discrepancies on water conversion and H2/CO ratio probably related to the influence of steam in radical chain-scission the model allows to describe gas production and hydrocarbons evolution providing important support for modeling and sizing of fluidized bed reactors on an industrial scale.

Manufacturing of composites with designed failure

Abstract The failure of polymer composites is a very complex process, which mainly occurs as a result of interactions between different types of damage in the material, often at random locations and without any particular signs. To increase the reliability of composites and enable their wider use in safety-critical components, it is crucial to make their failure processes more controllable and predictable, which could be achieved by the local modification of the interfacial adhesion. The aim of our research is to develop and investigate a method for designing the failure process of polymer composites in terms of the location and the mode of failure. We produced interfacially engineered composites containing a weakened adhesion zone by adding polycaprolactone (PCL) thermoplastic interlayer material, which was applied directly on the surface of the reinforcing material by fused filament fabrication (FFF). Then, material tests were carried out, and the failure mode and position were evaluated as a function of the geometry of the interlayer material.

Manufacturing of hexagonal cross-section thermoplastic matrix composite parts with automatic filament winding system

Thermoplastic filament winding is a flexible manufacturing method typically used in the production of cylindrical composite structures, allowing for in-situ consolidation without the need for a second consolidation step. The objective of this study is to produce non-cylindrical geometries, typically manufactured using thermoset matrix composites according to the literature, using the thermoplastic filament winding process. For this purpose, glass fiber (GF) reinforced polypropylene (PP) prepreg tapes were used to produce hexagonal cross-section thermoplastic composite parts. The critical process parameters; hot-air heater nozzle temperature, compression roller pressure, the linear speed of mandrel rotation, and corner radius of the mandrel, were determined using the Taguchi experimental design method. The interlaminar shear strength (ILSS) and maximum compressive strength (σmax) values were obtained as 211 MPa and 49.40 MPa as maximum, respectively. ANOVA analysis showed that the corner radius had the most significant impact on ILSS, while mandrel rotation speed and temperature were critical for σmax.

Creep assessment of thermoplastic materials for non-structural components in marine engines

The substitution of metals with fiber-reinforced polymers represents a well-established practice in the automotive and aerospace industries, driven by advantages such as cost reduction, weight savings, and environmental benefits. In the marine engineering sector, there is a growing interest in this metal replacement trend, particularly for non-structural components of marine engines that can be produced by adopting proper fiber-reinforced thermoplastic polymers. However, evaluating the suitability of such materials for marine applications necessitates a thorough understanding of their creep behavior, given the demanding operational environments and strict safety standards. The material selection process must intricately consider the material's susceptibility to creep through tailored material design methodologies. Moreover, redesign activities should aim to leverage the material's creep-resistant properties while ensuring adequate strength and simplifying installation procedures. Unfortunately, unlike the automotive industry, testing innovative plastic components in real environments on working engines is quite impossible. Neither engine manufacturers nor owners would allow jeopardizing their machinery by installing technologies not yet certified in a delicate environment such as a ship's engine room. In this context, finite element simulations offer a valuable tool to assess the material's creep performance and validate the proposed design when experimental measurements cannot be performed, hence predicting the component behavior over its intended lifetime. This study aims to exploit finite element analysis to evaluate the creep behavior and suitability for marine engine applications of a fiber-reinforced thermoplastic material, focusing on a camshaft cover of a four-stroke marine engine currently manufactured from aluminum alloy. Through numerical simulations, a commercial 30 % wt GFs/PA6,6 thermoplastic composite emerges as a promising candidate, demonstrating adequate creep resistance while significantly reducing weight, processing costs, and energy consumption. The results obtained from the present study lay the foundations for the adoption of such material-based technology also in the marine engine sector despite the difficulties coming from the peculiarities of this industry.

Enhancing 3D Printing Copper-PLA Composite Fabrication via Fused Deposition Modeling through Statistical Process Parameter Study.

The rapid advancement of additive manufacturing (AM) technologies has provided new avenues for creating three-dimensional (3D) parts with intricate geometries. Fused Deposition Modeling (FDM) is a prominent technology in this domain, involving the layer-by-layer fabrication of objects by extruding a filament comprising a blend of polymer and metal powder. This study focuses on the FDM process using a filament of Copper-Polylactic Acid (Cu-PLA) composite, which capitalizes on the advantageous properties of copper (high electrical and thermal conductivity, corrosion resistance) combined with the easily processable thermoplastic PLA material. The research delves into the impact of FDM process parameters, specifically, infill percentage (IP), infill pattern (P), and layer thickness (LT) on the maximum failure load (N), percentage of elongation at break, and weight of Cu-PLA composite filament-based parts. The study employs the response surface method (RSM) with Design-Expert V11 software. The selected parameters include infill percentage at five levels (10, 20, 30, 40, and 50%), fill patterns at five levels (Grid, Triangle, Tri-Hexagonal, Cubic-Subdivision, and Lines), and layer thickness at five levels (0.1, 0.2, 0.3, 0.4, and 0.5 mm). Also, the optimal factor values were obtained. The findings highlight that layer thickness and infill percentage significantly influence the weight of the samples, with an observed increase as these parameters are raised. Additionally, an increase in layer thickness and infill percentage corresponds to a higher maximum failure load in the specimens. The peak maximum failure load (230 N) is achieved at a 0.5 mm layer thickness and Tri-Hexagonal pattern. As the infill percentage changes from 10% to 50%, the percentage of elongation at break decreases. The maximum percentage of elongation at break is attained with a 20% infill percentage, 0.2 mm layer thickness, and 0.5 Cubic-Subdivision pattern. Using a multi-objective response optimization, the layer thickness of 0.152 mm, an infill percentage of 32.909%, and a Grid infill pattern was found to be the best configuration.

Decorative 3D printing on textiles using elastomer TPU filament under different printing conditions

Purpose New sustainable approaches to fashion products are needed due to the demand for customization, better quality and cost reduction. Therefore, the decoration of fashion products using 3D printing technology can create a new direction for manufacturing science. Design/methodology/approach This study aims to optimize the 3D printing of soft TPU material on textiles. In the past decade, trials of using 3D printing in tailored fashion products have been done due to the 3D printing simplicity, low cost of materials and time reduction. Therefore, soft polymers can be multi-layer stepped-deposited smoothly with the fused filament fabrication process. Findings Even though there have been many attempts in the literature to 3D print multilayer polymer filaments directly onto textile fabrics by special-purpose 3D printers, only a few reports of decorative or personalized artefact 3D printing using open-platform filament material extrusion 3D printers. Printing speed, nozzle Z distance, textile fabric thickness and deposited strand height significantly affect 3D printing on textile fabric. Originality/value This study investigates the potential of 3D printing on textiles by changing the printing speed, nozzle hot end, Z distance and layer thickness. It presents two critical case studies of 3D printing soft thermoplastic polyurethane material on a cotton T-shirt and on a tulle textile to reveal the 3D printing on textile fabrics manufacturing challenges.

Orientation of Chitin Nanofibers Dispersed in a Thermoplastic Polymer Matrix Through Dry Thermal Stretching

AbstractNanostructures derived from structural polysaccharides, such as cellulose and chitin, are notable for their sustainability, lightweight properties, and superior mechanical attributes. The macroscopic performance of these materials largely depends on the orientation of nanostructures. This study explores the preferential orientation of chitinous nanofibers (NFs) within a thermoplastic polymer matrix (PM) comprising poly(N‐vinylpyrrolidone) and glycerol, achieved through dry thermal stretching techniques. Altering the PM composition enables the modulation of the system's glass transition temperature (Tg). Chitin NFs are effectively dispersed within the PM, with their orientation enhanced by stretching at temperatures ≈30 °C above the Tg of the composites, resulting in an elongation at rupture (ε) of 105%. Under similar temperature conditions, composites with chitosan NFs show strong interactions with the PM, hindering the stretching process (ε = 10%). In contrast, composites with acetylated chitin NFs demonstrate increased stretchability (ε = 170%) but have insufficient interactions to stabilize their orientation. These interactions, identified as hydrogen bonds through FTIR, vary significantly based on the functional groups present on the NF surfaces. This variation is supported by DSC and dynamic mechanical analysis. Oriented ChNFs hold potential for bioactive applications.

Thermoplastic Starch Processed under Various Manufacturing Conditions: Thermal and Electrical Properties.

Eco-friendly materials like carbohydrate-based polymers are important for a sustainable future. Starch is particularly promising because of its biodegradability and abundance but its processing to thermoplastic starch requires optimization. Here we developed thermoplastic maize starch materials based on three manufacturing protocols, namely: (1) starch/glycerol manual mixing and extrusion, (2) starch/glycerol manual mixing, extrusion, and kneading, (3) starch/glycerol/water manual mixing and kneading. The physical properties were investigated by differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy. As expected from a partially miscible blend, the dielectric spectra revealed two distinct α-relaxations for the glycerol-rich and the starch-rich phases, respectively. By employing kneading after extrusion, the miscibility between the two phases was found to improve based on thermal and dielectric methods. Moreover, the addition of water during the premixing stage was observed to facilitate phase separation between starch and glycerol, with the α-relaxation dynamics of the latter being comparable to pure glycerol.