Dynamic Mechanical Thermal Analysis Research Articles

Influence of Air Humidity Level on the Structure and Mechanical Properties of Thermoplastic Starch-Montmorillonite Nanocomposite during Storage.

Thermoplastic starch (TPS) consisting of corn starch and glycerol as a plasticizer, and TPS-montmorillonite (MMT) nanocomposite were stored at room temperature in the air with relative humidities (RH) of 11, 55 and 85% for seven weeks. Mechanical testing and dynamic mechanical thermal analysis (DMTA) were performed to detect changes in their mechanical properties. Solid-state NMR spectroscopy monitoring the changes in molecular mobility in the samples provided an insight into relations between mechanical properties and local structure. The results of mechanical testing indicated that the addition of MMT results in the increase in the tensile strength and Young's modulus while elongation at break decreased, indicating the reinforcing effect of MMT. DMTA experiments revealed a decrease in glass transition temperature of starch-rich phase below room temperature for samples stored at higher RH (55 and 85%). This indicates that absorbed water molecules had additional plasticizing effect on starch resulting in higher mobility of starch chain segments. Recrystallization in these samples was deduced from the shape of cross-polarization magic-angle spinning 13C NMR spectra. The shape of broad-line 1H NMR spectra reflected changes in molecular mobility in the studied samples during seven weeks of storage and revealed that a high amount of water molecules impacts the starch intermolecular hydrogen bond density.

Effects of artificial weathering in NR/SBR elastomer blends

Degradation of polymer blends occurs by the constituent phases undergoing distinct chemical changes that depend on their unique chemical structures. This makes predicting and establishing a structure-property relationship for each phase necessary as well as challenging. In this work, the molecular and physical changes occurring in sulfur-cross-linked natural rubber (NR), styrene−butadiene rubber (SBR), and their 50/50 blend subjected to accelerated weathering are analyzed by 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, atomic-force microscopy (AFM), and dynamic mechanical thermal analysis (DMTA). NMR transverse relaxation time (T2) studies suggest the formation of rigid components due to weathering. FTIR and AFM reveal that this is related to the formation of a stiff surface due to chemical modifications, which shows up as an additional thermal transition in the DMTA curves. Low-field double-quantum (DQ) NMR studies of the cross-link density, by the residual dipolar coupling constant (Dres), of SBR show a continuous increase in its cross-link density over the weathering duration (988 h). In contrast, NR exhibits dominant chain scission reactions resulting in defects, with both materials demonstrating the formation of different chain lengths. During the first 168 h, NR also undergoes modification of sulfur bond lengths, which is also observed in the blend. The blend largely follows an intermediate trend of cross-link densities compared to the two polymers but shows signs of lesser chain modifications than a weighted average of the two polymers. This is confirmed by phase-resolved DQ magic-angle spinning (MAS) NMR experiments whereby the peak-specific Dres of the blend was measured to be less modified than that of the individual vulcanizates, thus proving that the blend is more resistant to weathering than its constituent elastomers.

Effect of Post-Printing Cooling Conditions on the Properties of ULTEM Printed Parts

This paper aimed to estimate the effect of post-printing cooling conditions on the tensile and thermophysical properties of ULTEM® 9085 printed parts processed by fused deposition modeling (FDM). Three different cooling conditions were applied after printing Ultem samples: from 180 °C to room temperature (RT) for 4 h in the printer (P), rapid removal from the printer and cooling from 200 °C to RT for 4 h in the oven (O), and cooling at RT (R). Tensile tests and dynamic mechanical thermal analysis (DMTA) were carried out on samples printed in three orthogonal planes to investigate the effect of the post-printing cooling conditions on their mechanical and thermophysical properties. Optical microscopy was employed to relate the corresponding macrostructure to the mechanical performance of the material. The results obtained showed almost no difference between samples cooled either in the printer or oven and a notable difference for samples cooled at room temperature. Moreover, the lowest mechanical performance and sensitivity to the thermal cooling conditions were defined for the Z printing direction due to anisotropic nature of FDM and debonding among layers.

Carbon reinforced concrete exposed to high temperatures

AbstractThe material behavior of carbon reinforced concrete exposed to high temperatures was examined in 118 tensile and 81 bond tests using two material combinations. This analysis served to determine resilient material values under temperature influence for current carbon reinforcements and to show starting points for further test series. In this article, the test specimens for the tensile and bond tests are described in detail as well as the used test setup. Special attention is given to the physical–chemical behavior of the impregnated material, which were analyzed namely with dynamic mechanical thermal analysis (DMTA) and thermal gravimetric analysis (TGA). Finally, the results of the tensile and bond tests under different temperature exposures are presented and classified.

Efficient and reliable encapsulation for perovskite/silicon tandem solar modules.

Perovskite/silicon tandem solar cells have a tremendous potential to boost renewable electricity production thanks to their very high performance combined with promising cost structure. However, for actual field deployment, any solar cell technology needs to be assembled into modules, where the associated processes involve several challenges that may affect both the performance and stability of the devices. For instance, due to its hygroscopic nature, ethylene vinyl acetate (EVA) is incompatible with perovskite-based photovoltaics. To circumvent this issue, we investigate here two alternative encapsulant polymers for the packaging of perovskite/silicon tandems into minimodules: a thermoplastic polyurethane (TPU) and a thermoplastic polyolefin (TPO) elastomer. To gauge their impact on tandem-module performance and stability, we performed two internationally established accelerated module stability tests (IEC 61215): damp heat exposure and thermal cycling. Finally, to better understand the thermomechanical properties of the two encapsulants and gain insight into their relation to the thermal cycling of encapsulated tandems, we performed a dynamic mechanical thermal analysis. Our understanding of the packaging process of the tandem module provides useful insights for the development of commercially viable perovskite photovoltaics.

Fabricated coordinate and ionic bonds in chemically cross‐linked ethylene acrylic elastomer for high‐performing elastomers

AbstractCovalent bond cross‐link networks endow rubber with unique resiliency enabling it to be widely used as a series of irreplaceable materials in modern life. However, the balance between rigidity and toughness, which is highly desired with the growing demand for high‐performance rubber, remains a significant challenge for covalent bond networks. In this study, magnesium oxide (MgO) was filled in an ethylene acrylic elastomer (AEM) to construct both ionic cluster and coordinate bonds within the framework of a covalent cross‐link network, which significantly improved the properties of AEM. The MgO‐filled AEM was measured through Fourier transform infrared spectroscopy and thermogravimetric analysis, using a universal testing machine, dynamic mechanical thermal analyzer, and rubber process analyzer. As the multi‐bond network was successfully constructed, the tensile strength was enhanced by almost 10 times, and unexpected dynamic properties were exhibited with a higher elastic modulus (rigidity) attributed to ionic clusters and a higher loss factor (toughness) attributed to the coordinate bonds. With the efficient enhancement of the mechanical properties, the improved toughness can dissipate energy to preserve the integrity of rubber under the application of an external mechanical force.

Load-bearing analysis of polymer nanocomposite gears using a temperature-based step loading technique: Experimental and numerical study

The load-bearing characteristic of polyoxymethylene (POM)/carbon black (CB)/CaCO3 ternary nanocomposite gears were assessed using a temperature-based step loading approach. An online temperature measuring system was integrated into the gear test rig to continuously measure the gears’ bulk temperature. Dynamic mechanical thermal analysis (DMTA) was performed to explore a correlation between the viscoelastic characteristics, failure, and wear behavior of nanocomposite gears. The step loading test results showed that the load-bearing capacity was incremented from 7 Nm for pure POM to 10 Nm for POM/CB/3CaCO3 ternary nanocomposite gear. The finite element analysis of gears indicated that the maximum contact stress was different for those with similar critical torque. It was suggested that the maximum contact stress could complement the step loading technique in defining the load-carrying capacity of polymer-based gears. The failure analysis indicated the impediment of tooth cracking and thermal bending in ternary nanocomposite gears. The scanning electron microscopy (SEM) micrographs showed a much smoother tooth worn surface with minor traces of surface cracks and plastic flow for ternary nanocomposites, assigned to the promoted wear resistance, elastic response, and lower hysteretic self-heating due to the synergetic reinforcing effects of CB and nano-CaCO3.

High Performance of Titanium Dioxide Reinforced Acrylonitrile Butadiene Rubber Composites

Recently, dielectric elastomer actuators (DEA) have emerged as one of the most promising materials for use in soft robots. However, DEA needs a high operating voltage and high mechanical properties. By increasing the dielectric constant of elastomeric materials, it is possible to decrease the operating voltage required. Thus, elastomeric composites with a high dielectric constant and strong mechanical properties are of interest. The aim of this research was to investigate the effect of titanium dioxide (TiO2) content ranging from 0 to 110 phr on the cure characteristics, and physical, dielectric, dynamic mechanical, and morphological properties of acrylonitrile butadiene rubber (NBR) composites. The addition of TiO2 reduced the scorch time (ts1) as well as the optimum cure time (tc90) but increased the cure rate index (CRI), minimum torque (ML), maximum torque (MH), and delta torque (MH - ML). The optimal TiO2 content for maximum tensile strength and elongation at break was 90 phr. Tensile strength and elongation at break were increased by 144.8% and 40.1%, respectively, over pure NBR. A significant mechanical property improvement was observed for TiO2-filled composites due to the good dispersion of TiO2 in the NBR matrix, which was confirmed by scanning electron microscopy (SEM). Moreover, incorporating TiO2 filler gave a higher storage modulus, a shift in glass transition temperature (Tg) to a higher temperature, and reduced damping in dynamic mechanical thermal analysis (DMTA). The addition of TiO2 to NBR rubber increased the dielectric constant of the resultant composites in the tested frequency range from 102 to 105 Hz. As a result, TiO2-filled NBR composite has a high potential for dielectric elastomer actuator applications.

Polyethylene reinforced by biomimetic (polydopamine, tannic acid) modified magnesium oxysulfate whisker: Mechanical properties, thermal properties and flame retardancy

Two-dimensional magnesium oxysulfate whisker (MOSw) was modified by polydopamine (PDA) and tannic acid (TA) instead of the traditional inorganic flame retardants activated by silane coupling agent ( γ -methacryloxypropyltrimethoxy silane, KH570) such as Mg(OH) 2 and Al(OH) 3 . Differential scanning calorimeter (DSC) results showed that MOSw could act as heterogeneous nucleation for crystallization of HDPE, and further increased the initial crystallization temperatures of composites treated with PDA and TA. Dynamic mechanical thermal analysis (DMTA) showed that both the storage modules and loss modules of the composites with modified MOSw were significantly increased, which suggested the improved compatibility and dispersion between the modified MOSw and matrix. The tensile strengths of HDPE/MOSw@PDA composite and HDPE/MOSw@TA composite could be 118.0% and 121.2% higher than that of HDPE/MOSw@KH570 composite, and the corresponding impact strengths could be 124.0% and 111.2% higher, respectively. Compared to HDPE, the synergistic effect of PDA- MOSw and TA- MOSw (combustion heat through the dehydration of MOSw, gas-phase flame-retarded effect of MOSw, scavenging of active free radicals) increased the limit oxygen index (LOI) of composites from 19.4% to 23.4% and 23.8%, respectively, which were higher than 20.6% of traditional HDPE/Al(OH) 3 @KH570 composite with the same 30 wt.% filler. Schematic of self-polymerization of dopamine, and chelation of tannic acid with metal ions • MOSw covered with PDA and TA substituted for the traditional inorganic flame retardants activated by silane coupling agent. • Different from traditional inorganic flame retardants such as Mg (OH) 2 and Al (OH) 3 , MOSw modified by PDA and TA could not only improved the flame retardancy of HDPE, but also improved the tensile strength to a certain extent. • The composites with MOSw modified by PDA and TA showed good thermal stability.

Flexural behavior of pMWCNTs filled glass fiber/epoxy nanocomposites: Synthesis and interfacial failure

AbstractGlass fiber reinforced polymer composite (GFRP) encounter many practical situations during its application, exposed to different temperature fluctuation. Absorption of moisture and the fluctuated thermal environment cause mechanical degradation of GFRP. The current plan is to explore the mechanical and chemical behavior of pristine multiwall carbon nanotubes(pMWCNTs)‐glass fiber strengthens epoxy composites during thermal shock (TS). The laminates were prepared by the hand‐lay‐up process followed by compression molding. The thermal shock was performed at the temperature for the required samples was 135°C for 24 h, followed by −135°C for 24 h. A flexural test has been carried out at 1 mm/min loading speed. 0.2 wt% pMWCNTs filled nanocomposite appeared to have the highest flexural strength and modulus compared to ambient samples. The thermomechanical behavior of nanocomposites has been accomplished by analyzing the dynamic mechanical thermal analysis graph (DMTA). Field emission scanning electron microscope (FESEM) analyzed the fracture surface of in‐situ mechanical failure samples to find out the primary failure modes for strengthening and weakening mechanisms. The glass transition temperature (Tg) of the nanocomposite observed decreased due to homogeneous dispersion of pMWCNTs, imparting some effect on crosslink density and reinforcement up to 0.2 wt%. This study reveals that the uniform distribution of pMWCNTs and thermal shock treatment enhances the matrix stiffness and improves the mechanical properties.

Weathering resistance (UV-shielding) improvement of a polyurethane automotive clear-coating applying metal-organic framework (MOF) modified GO nano-flakes (GO-ZIF-7)

In this research, ZIF-7 particles were synthesized over graphene oxide (GO) nanosheets and characterized through various techniques. Then, the influence of the fabricated GO-ZIF-7 nano-hybrids on the weathering resistance and physical-mechanical performance of the PU coatings were investigated. The weathering resistance of PU/GO-ZIF-7, PU/GO, and control PU was examined with the aid of QUV accelerated weathering conditions via several methods such as recording gloss retention and contact angle changes, FTIR, colorimetric, FE-SEM, and AFM analysis. For the PU/GO-ZIF-7 nanocomposite coating exposed to accelerated weathering condition, the changes in carbonyl group relate peak and urethane linkage were less than the changes of these parameters for the control PU sample. The change in the color component (Δb*) decreased to 56.9% of PU/GO-ZIF-7 compared to control PU (70.9%). The change of root mean square (RMS) roughness value of PU/GO-ZIF-7 was less than that of control PU (from 9.44 to 8.04 nm vs. from 14.89 to 8.02 nm). As a result, after a long weathering exposure (UV-A), the fewer changes in aesthetic properties, chemical structure, and topology of the PU/GO-ZIF-7 coating led to less surface degradation and better weathering stability performance. The GO-ZIF-7 nano-hybrids revealed that they are capable of improving the photo-stability of PU coatings by the mixed mechanisms of absorbing UV rays and free radical scavengers. The physical-mechanical characteristics of the nanocomposites were analyzed using dynamic mechanical thermal analysis (DMTA) and tensile tests. The addition of GO-ZIF-7 to PU led to an above 70% and 85% increase of elongation at break and toughness concerning the control PU, respectively.

Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine.

In this study a new type of bifunctional epoxy compound (DDSQ-EP) based on double-decker silsesquioxane (DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction with dichloromethylvinylsilane, followed by epoxidation reaction of vinyl groups. The resultant structures were confirmed using Fourier transform infrared spectrometry, nuclear magnetic resonance spectrometry and time-of-flight mass spectrometry, respectively. The DDSQ-EP was incorporated into polybenzoxazine to obtain the PBZ/DDSQ-EP nanocomposites. The uniform dispersion of DDSQ-EP in the nanocomposites was verified by X-ray diffraction and scanning electron microscope. The reactions occurred during the curing of the composites and were investigated using infrared spectroscopy of segmented cures. Dynamic mechanical analysis and thermal gravimetric analysis indicated that the storage modulus, glass transition temperature and thermal stability of PBZ/DDSQ-EP were increased in comparison with pure benzoxazine resins. Assessment of dielectric properties demonstrated that the dielectric permittivity and dielectric loss of polybenzoxazine decreased slightly because of the addition of DDSQ-EP.

Improved thermostimulative shape memory behavior of HDPE/PET immiscible blend‐based polymer nanocomposite using amphiphilic Janus nanoparticles

AbstractIn the study, the impact of homogeneously modified (HM) and Janus silica nanoparticles on the thermostimulative shape memory effect of high‐density polyethylene/poly(ethylene terephthalate) blend‐based polymer nanocomposites (BPN) is investigated. It is shown that the physical/mechanical characteristics of the polymer/polymer interface have a determinative role in defining the shape memory effect of the system. Accordingly, the effect of each nanoparticle type on this region is precisely evaluated and interpreted. The Janus nanoparticles are synthesized via a two‐step desymmetrization process in Pickering emulsion, using different polar/apolar silane agents, while a single‐step modification procedure is used to perform the homogenous modification. The designing stages of a comprehensive analytical model are discussed which is used to evaluate the corporation level of the HM and Janus nanoparticles in the recovery mechanism of the BPN samples. The results of different characterizing tests (e.g., tensile, recovery, dynamic mechanical thermal analysis, rheology, etc.) are proposed to demonstrate the impact of different types of nanoparticles on the polymer/polymer interface and shape memory effect (SME) in each sample. It is proved that the BPN samples containing Janus nanoparticles have the strongest SME, in both stretching and bending modes, even better than similar systems containing small molecule compatibilizers.

3D printing of PLA-TPU with different component ratios: Fracture toughness, mechanical properties, and morphology

In this study, three PLA-TPU compounds were prepared by the melt mixing method and after the process of compounding, filament preparation, and 3D printing with Fused Deposition Modeling (FDM). The mechanical properties under compression, tensile, bending, shear modes, and fracture toughness were comprehensively and experimentally assessed. Also, for thermal analysis and microstructural evaluation, Dynamic Mechanical Thermal Analysis (DMTA) and Scanning Electron Microscopy (SEM) were used. The thermal analysis of the PLA-TPU compounds showed an increase and decrease in the loss and storage modulus with increasing PLA value, while all compounds had almost the same glass transition temperature. The results of mechanical tests showed that by raising the amount of PLA, the strength and formability increased and decreased, respectively in all loading modes. The UTS values for PLA50, PLA70, and PLA90 were achieved 27.27 MPa, 40.91 MPa, and 54.18 MPa, respectively. Also, the fracture toughness results were consistent with the mechanical properties. The PLA90 had 1.69 and 2.36 times higher fracture toughness than the PLA70 and PLA50 compounds, respectively. SEM images showed that with the increase in the amount of TPU, the voids caused by the printing and neck growth due to the incomplete integration of the inter and intralayer rasters rises, which is the reason for the decrease in strength and printability. The shear test results also confirmed the SEM images quantitatively and showed that the connection between the layers and density improves with increasing the amount of PLA.

Molecular weight effects on the stress-relaxation behavior of soft thermoplastic elastomer by means of temperature scanning stress relaxation (TSSR)

The mechanical properties of multiblock copolymer thermoplastic elastomers (TPEs) are governed by the interplay of different reversible dynamics [e.g., hard block (HB) association and chain entanglements]. Understanding how these physical processes influence the high-temperature deformation behavior is relevant as many TPEs lose toughness with increasing temperature. Increasing molecular weight (Mw) improves their temperature resistance that is attributed to an increase in network connectivity. Indeed, longer chains are characterized by more HBs per chain and by a longer lifetime of the entanglements in the amorphous phase. Both the associating HB and disentanglement dynamics are temperature and rate dependent. To further understand the interconnected role of Mw, temperature and rate dependencies on the mechanical properties, we perform Temperature Scanning Stress Relaxation (TSSR) tests. The method consists of measuring the stress relaxation of the materials as the temperature monotonically increases, allowing us to probe the stress response as the HBs progressively disassociate due to the increase in temperature. The results show that increasing Mw improves the high-temperature relaxation behavior, allowing the material to retain more stress than its low Mw counterpart as the temperature increases. This distinction does not show itself when performing standard small strain dynamic mechanical thermal analyses. Depending on the deformation experienced before the TSSR is performed, different relaxation behaviors are observed illustrating the importance of the current microstructure in determining the mechanical properties. The TSSR approach is well-suited to benchmark the high-temperature stress-bearing properties of network-based polymers whose morphology and, hence, properties are strongly deformation dependent.

Magnetic‐Oriented Nickel Particles and Nickel‐Coated Carbon Nanotubes: An Efficient Tool for Enhancing Thermal Conductivity of PDMS Composites

AbstractIn this study, PDMS composites are thermally cured with nickel particles and nickel‐coated carbon nanotubes as fillers. Both fillers are oriented with the aim to increase the thermal conductivity of the silicone polymer network, due to the formation of a continuous thermal path. Scanning electron microscopy (SEM) gives a picture of the polymer network's morphology, proving the effective alignment of the nickel particles. Rheology and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) studies confirm the full curing of the silicon network and no influence in the curing kinetics of the type and content of fillers and their orientation. Dynamic mechanical thermal analysis (DMTA) and tensile analysis show instead different thermo‐mechanical behavior of the polymer network due to the presence of different fillers, different fillers percentage, and orientation. Finally, the thermal transmittance coefficient (k) is studied by means of hot disk analysis, revealing the increment of almost 200% due to magnetic filler orientation.

Influence of UV Radiation on Mechanical Properties of Polymer Optical Fibers.

This paper presents an analysis of the mechanical properties of different polymer optical fibers (POFs) at ultraviolet (UV) radiation conditions. Cyclic transparent optical polymer (CYTOP) and polymethyl methacrylate (PMMA) optical fibers are used in these analyses. In this case, the fiber samples are irradiated at the same wavelength, pulse time and energy conditions for different times, namely, 10 s, 1 min, 2 min and 3 min. The samples are tested in tensile tests and dynamic mechanical thermal analysis (DMTA) to infer the variation in the static and dynamic properties of such fibers as a function of the UV radiation condition. Furthermore, reference samples of each fiber (without UV radiation) are tested for comparison purposes. The results show a lower UV resistance of PMMA fibers, i.e., higher variation in the material features in static conditions (Young's modulus variation of 0.65 GPa). In addition, CYTOP fiber (material known for its high UV resistance related to its optical properties) also presented Young's modulus variation of around 0.38 GPa. The reason for this reduction in the moduli is related to possible localized annealing due to thermal effects when the fibers are subjected to UV radiation. The dynamic results also indicated a higher variation in the PMMA fibers storage modulus, which is around 30% higher than the variations in the CYTOP fibers when different radiation conditions are analyzed. However, CYTOP fibers show a smaller operational temperature range and higher variation in the storage modulus as a function of the temperature when compared with PMMA fibers. In contrast, PMMA fibers show higher variations in their material properties when subjected to oscillatory loads at different frequency conditions. Thus, the results obtained in this work can be used as guidelines for the influence of UV radiation in POFs not only for the material choice, but also on the limitations of UV radiation in the fabrication of the grating as well as in sensor applications at UV radiation conditions.

Dynamic mechanical thermal analysis of unaged and hygrothermally aged discontinuous Bouligand structured CFRP composites

A dynamic mechanical thermal analyser operating in the single cantilever mode was used to examine the dynamic mechanical properties of unaged and hygrothermally aged discontinuous asymmetric helicoidal (Bouligand) carbon fibre reinforced plastic (CFRP) composites as a function of fibre architecture. The discontinuous Bouligand was manufactured using two major pitch angles as independent variables: 90° and 120° and from each major pitch angle, minor interply pitch angles were used as independent variables ranging 5°–25°. The composites were tested as either dry unaged specimens or following hygrothermal ageing in seawater at the constant temperatures of 40 °C and 60 °C for over 2000 h. We find that the viscoelastic properties E′ and E″ are adversely affected by both hygrothermal aging and the minor pitch angle, but not the major pitch angle. Higher hygrothermal ageing temperatures and increasing minor pitch angles are found to decrease the energy absorption and dissipation capacities of discontinuous Bouligand structured CFRP composites. The tan-δ curves also indicate that hygrothermal ageing increases the heterogeneity of discontinuous Bouligand structured composites, with separate viscoelastic phases and glass transition temperatures.

Waste Eggshells as a Natural Filler for the Poly(Vinyl Chloride) Composites.

The paper presents the characteristics of unplasticized PVC composites modified with biofiller obtained from the waste eggshells of hen eggs. The composites obtained by extrusion contained from 10 phr to 40 phr of biofiller. The filler was characterized using the SEM, TG, and sieve analysis methods. The influence of the filler on the processing properties was determined using plastographometric and MFR tests. Fundamental analysis of mechanical properties was also performed, i.e., Charpy impact strength and determination of tensile properties. The mechanical properties were supported with dynamical mechanical thermal analysis, time of thermal stability, and thermogravimetric analysis. Structure analysis was also performed using SEM and X-ray microcomputed tomography (micro-CT). The processing properties of the tested composites do not give grounds for disqualifying such material from traditional processing PVC mixtures. Notably, the biofiller significantly improves thermal stability. Ground eggshells (ES) work as scavengers for the Cl radicals released in the first stage, which delays the PVC chain’s decay. Additionally, a significant increase in the value of the modulus of elasticity and softening point (VST) of the composites concerning PVC was found. Ground hen eggshells can be used as an effective filler for PVC composites.

One-Shot Synthesis of Thermoplastic Polyurethane Based on Bio-Polyol (Polytrimethylene Ether Glycol) and Characterization of Micro-Phase Separation.

In this study, a series of bio-based thermoplastic polyurethane (TPU) was synthesized via the solvent-free one-shot method using 100% bio-based polyether polyol, prepared from fermented corn, and 1,4-butanediol (BDO) as a chain extender. The average molecular weight, degree of phase separation, thermal and mechanical properties of the TPU-based aromatic (4,4-methylene diphenyl diisocyanate: MDI), and aliphatic (bis(4-isocyanatocyclohexyl) methane: H12MDI) isocyanates were investigated by gel permeation chromatography, Fourier transform infrared spectroscopy, atomic force microscopy, X-ray Diffraction, differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. Four types of micro-phase separation forms of a hard segment (HS) and soft segment (SS) were suggested according to the [NCO]/[OH] molar ratio and isocyanate type. The results showed (a) phase-mixed disassociated structure between HS and SS, (b) hydrogen-bonded structure of phase-separated between HS and SS forming one-sided hard domains, (c) hydrogen-bonded structure of phase-mixed between HS, and SS and (d) hydrogen-bonded structure of phase-separated between HS and SS forming dispersed hard domains. These phase micro-structure models could be matched with each bio-based TPU sample. Accordingly, H-BDO-2.0, M-BDO-2.0, H-BDO-2.5, and M-BDO-3.0 could be related to the (a)—form, (b)—form, (c)—form, and (d)—form, respectively.