Dynamic Mechanical Thermal Analysis Research Articles

Influence of Programming and Recovery Parameters on Compressive Behaviors of 4D‐Printed Biocompatible Polyvinyl Chloride or Vinyl–Poly(ε‐Caprolactone) Blends

In this article, a new class of biocompatible shape‐memory polymers (SMPs) through blending pcolyvinyl chloride or vinyl (PVC) and poly(ε‐caprolactone) (PCL) is introduced. The compressive shape‐memory behaviors of 4D‐printed SMP PVC with 5 and 10 wt% of PCL are studied in detail. In this respect, a set of experiments are carried out to understand thermomechanical responses of PVC–PCL blends under various shape‐memory parameters like programming temperature, load‐holding time, applied strain, and recovery temperature. Dynamic mechanical thermal analysis and scanning electron microscope imaging are also performed to provide thermal and morphological analyses. It is found that by raising the recovery temperature from 45 to 65 °C, the shape recovery ratio increases from 5.63 to 7.92 MPa when the PVC–PCL10 is programmed via the hot‐programming (HP) protocol. The highest level of shape fixity (100%) and the best performance of stress relaxation are achieved for HP sample, while the highest shape recovery ratio (100%) is obtained for cold programming. By applying the load‐holding time, the amount of shape fixity can reach from 88.14% to 100%. Results of this research are expected to provide an insightful understanding of the shape‐memory behaviors of PVC–PCL and be instrumental for 4D printing and programming of shape‐adaptive structures like shape‐memory intervertebral cages as spinal support devices.

Highly efficient reactive compatibilization of biodegradable PBAT/EVOH blend by pMDI

AbstractPolymeric methylene diphenyl isocyanate (pMDI) was used as a reactive compatibilizer to improve the mechanical properties of the PBAT/EVOH blend. Initially, pMDI was blended with pure polymers. Adding pMDI led to a 10‐fold rise in the viscosity of PBAT/pMDI compared to pure PBAT, with an enhancement in tensile properties, attributed to pMDI's chain‐extending effect in the PBAT phase. Conversely, a reduction in the elongation at the break of EVOH/pMDI indicated a cross‐linking role for pMDI in the EVOH phase. Notably, the blend with 1 wt% of pMDI showed a high tensile strength of 38 MPa by route II, much above 13.5 MPa for the one prepared by route I, and 14 MPa for the blank PBAT/EVOH blend without pMDI. Fourier transform infrared (FTIR) spectra, FE‐SEM images, and dynamic mechanical thermal analysis (DMTA) results confirmed the occurrence of effective reactions in route II. Modification of the blend with pMDI decreased the crystallinity of EVOH, the size of EVOH droplets, and the oxygen transmission rate (OTR) of the blends. However, an increase in the pMDI content above 0.5 wt% decreased OTR. Therefore, the modified blends of PBAT/EVOH with pMDI can be used as an efficient compatibilizer or adhesive layer in PBAT/EVOH blends or multilayer films for agricultural or food packaging applications.

Composites of Poly(3-hydroxybutyrate) and Mesoporous SBA-15 Silica: Crystalline Characteristics, Confinement and Final Properties.

Several composites based on poly(3-hydroxybutyrate) (PHB) and mesoporous SBA-15 silica were prepared by solvent-casting followed by a further stage of compression molding. The thermal stability, phase transitions and crystalline details of these composites were studied, paying special attention to the confinement of the PHB polymeric chains into the mesopores of the silica. For that, differential scanning calorimetry (DSC) and real-time variable-temperature X-ray scattering at small angles (SAXS) were performed. Confinement was stated first by the existence of a small endotherm at temperatures around 20 °C below the main melting or crystallization peak, being later confirmed by a notable discontinuity in the intensity of the main (100) diffraction from the mesoporous silica observed through SAXS experiments, which is related to the change in the scattering contrast before and after the crystallization or melting of the polymer chains. Furthermore, the usual α modification of PHB was developed in all samples. Finally, a preliminary investigation of mechanical and relaxation parameters was carried out through dynamic-mechanical thermal analysis (DMTA). The results show, in the temperature interval analyzed, two relaxations, named α and β (the latest related to the glass transition) in order of decreasing temperatures, in all specimens. The role of silica as a filler is mainly observed at temperatures higher than the glass transition. In such cases, stiffness is dependent on SBA-15 content.

Dragline silk fibers from golden orb‐web spider Trichonephila clavata ensure structural and mechanical robustness against ultraviolet radiation

AbstractA diurnal spider, Trichonephila clavata (T. clavata), is often called a golden orb‐weaver because its dragline or lifeline silk fibers exhibit a golden color. However, little is known about the biological roles of the golden pigment. Meanwhile, Araneus ventricosus, which is a nocturnal spider, spins colorless silk fibers. Here, we investigated the effect of ultraviolet (UV) irradiation on physical properties of silk fibers obtained from these diurnal and nocturnal spiders. After UV exposure, the dragline silk of the nocturnal spiders appeared abraded and became insoluble due to gelation, whereas the diurnal spider silk remained intact. A dynamic mechanical thermal analysis under different humidity conditions revealed that the storage modulus of the silk from the nocturnal spider dropped markedly at low humidity levels after UV irradiation. This indicated that the molecular weight of this silk degraded under UV exposure and that the number of terminal amino and carboxyl groups increased due to the breakage of the main protein chains. In contrast, the structural and mechanical properties of the diurnal spider silk were maintained regardless of the UV irradiation. Therefore, the golden pigments in the dragline silk of T. clavata most likely played a role in protecting the silk from UV damage.

Phosphorus-Based Flame-Retardant Acrylonitrile Butadiene Styrene Copolymer with Enhanced Mechanical Properties by Combining Ultrahigh Molecular Weight Silicone Rubber and Ethylene Methyl Acrylate Copolymer.

The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR.

Dynamic Non-Covalent Exchange Intrinsic Self-Healing at 20 °C Mechanism of Polyurethane Induced by Interactions among Polycarbonate Soft Segments.

Two polyurethanes (PUs) were similarly synthesized by reacting a cycloaliphatic isocyanate with 1,4-butanediol and two polyols of different nature (polyester, polycarbonate diol) with molecular weights of 1000 Da. Only the PU synthesized with polycarbonate diol polyol (YCD) showed intrinsic self-healing at 20 °C. For assessing the mechanism of intrinsic self-healing of YCD, a structural characterization by molecular weights determination, infrared and X-ray photoelectronic spectroscopies, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis, and dynamic mechanical thermal analysis was carried out. The experimental evidence concluded that the self-healing at 20 °C of YCD was due to dynamic non-covalent exchange interactions among the polycarbonate soft segments. Therefore, the chemical nature of the polyol played a key role in developing PUs with intrinsic self-healing at 20 °C.

Enzymatic synthesis of furan-based copolymers: Material characterization and potential for biomedical applications.

Today's growing demand for advanced and sustainable polyester materials is driven by an increasing awareness of the environmental impact of traditional materials, emphasizing the need for eco-friendly alternatives. Sustainability has become central in materials development, including the biomedical area, where biobased and environmentally friendly solutions are a rapidly growing field. This research aims to comprehensively evaluate a new enzymatically catalyzed furan-based copolymer, poly(decamethylene furanoate)-co-(dilinoleic furanoate) (PDF-DLF), with a 70-30 wt% hard-to-soft segment ratio. Then, its performance across medical applications is explored, with a particular focus on its potential as a nanofibrous scaffolding material. PDF-DLF was synthesized from biobased monomers using Candida antarctica lipase B (CAL-B) as the biocatalyst. Material characterization included dynamic mechan‑ical thermal analysis (DMTA) to assess the mechanical behavior and thermal properties. Enzymatic degradation studies determined biodegradability, while cytotoxicity tests established in vitro biocompatibility. The copolymer was electrospun into nanofibers, with scanning electron microscopy (SEM) employed to analyze their morphology. PDF-DLF displays mechanical and thermal properties indicating high storage modulus and 2 main temperature transitions. Enzymatic degradation studies and cytotoxicity assessments confirm biodegradability and in vitro biocompatibility. Electrospinning successfully transformed the copolymer into nanofibers with diameters ranging from 500 nm to 700 nm. This study significantly advances our understanding of sustainable polyesters with versatile processing capabilities. The successful electrospinning highlights its potential as a biodegradable scaffold for medical engineering, supported by biocompatibility and sufficient mechanical properties. It opens new opportunities for sustainable materials in critical biomedical industries, including tissue engineering.

Thermophysical Properties of Composite Metal-Filled Copolymers of Polyvinylpyrrolidone

The effect of the presence of finely dispersed metal fillers of various natures (Zn, Co, Ni) on the thermophysical characteristics (Vick heat resistance, glass transition temperature) of polyvinylpyrrolidone block copolymers with 2-hydroxyethylmethacrylate was studied. It was found that the heat resistance of the obtained composites significantly exceeds the heat resistance of unfilled copolymers and is in the range of 360-395K, depending on the nature and content of the metal filler. The change in heat resistance correlates with the change in glass transition temperature, which was evaluated according to the results of thermomechanical and dynamic mechanical thermal analyses. The results of this work are an additional source to characterize the structure of metal-filled copolymers: they confirm the participation of metal filler particles in the formation of the nodes of the copolymer spatial network, and also prove the formation of a different polymer network structure in the interfacial layer on the surface of the metal particle and in the polymer volume.

Effects of carbon‐based nanoparticles on the properties of poly(lactic acid) hybrid composites containing basalt fibers and carbon‐based nanoparticles processed by injection molding

AbstractIn this study, we developed composites with a poly(lactic acid) matrix and reinforced with basalt fiber, carbon‐based nanoparticles (carbon nanotube [CNT] and expanded graphene [GNP]), and both basalt fiber and nanoparticles (hybrid composites). The composites were produced by extrusion, and then tensile specimens were injection molded from the composites. The hybrid composites exhibited enhanced mechanical properties. The reinforcing materials increased crystallinity; this was more pronounced for hybrid composites. We experienced significant increase in the glass transition temperature, which proves the better interaction between the reinforcing and the matrix phases. Dynamic mechanical thermal analysis showed that the nanoparticles increased the storage modulus both alone and in combination with basalt fibers. Furthermore, the basalt fiber‐reinforced composites and hybrids exhibited significant modulus above the glass transition temperature. Based on scanning electron microscopy images of the fracture surfaces, we concluded that adding basalt fibers during compounding resulted in better dispersion of the nanoparticles.Highlights Poly(lactic acid) (PLA) reinforced with basalt fiber has good strength properties. Graphene hybrid exhibits notable tensile modulus improvement in hybrids. Graphene and carbon nanotubes are crystalline nucleating agents for PLA. Enhanced nanoparticle distribution was discovered for hybrid composites. The glass transition temperature of PLA increases with reinforcement.

Development of starch-rich thermoplastic polymers based on mango kernel flour and different plasticizers

This work reports on the development of starch-rich thermoplastic based formulations produced by using mango kernel flour, avoiding the extraction process of starch from mango kernel to produce these materials. Glycerol, sorbitol and urea at 15 wt% are used as plasticizers to obtain thermoplastic starch (TPS) formulations by extrusion and injection-moulding processes. Mechanical results show that sorbitol and urea allowed to obtain samples with tensile strength and elongation at break higher than the glycerol-plasticized sample, achieving values of 2.9 MPa of tensile strength and 42 % of elongation at break at 53 % RH. These results are supported by field emission scanning electron microscopy (FESEM) micrographs, where a limited concentration of voids was observed in the samples with sorbitol and urea, indicating a better interaction between starch and the plasticizers. Thermogravimetric analysis (TGA) shows that urea and sorbitol increase the thermal stability of TPS in comparison to the glycerol-plasticized sample. Differential scanning calorimetry (DSC) and dynamic-mechanical-thermal analysis (DMTA) verify the increase in stiffness of the sorbitol and urea plasticized TPS and also illustrate an increase in the glass transition temperature of both samples in comparison to the glycerol-plasticized sample. Glass transition temperatures of 45 °C were achieved for the sample with sorbitol.

Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth.

In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant.

Influence of LLDPE on the mechanical properties improvement of 3D printed POE/LLDPE blends

AbstractPolyolefins and polyolefin elastomers (POEs) are widely used in various applications due to their unique properties. However, their use in 3D printing has been limited due to challenges such as excessive softness, shrinkage, warpage, and poor mechanical properties. In this study, two strategies were employed to enhance the performance of POEs in 3D printing. First, POE was blended with 10%, 30%, and 50% percentages of linear low‐density polyethylene (LLDPE) to improve the material's mechanical properties and printability. Second, a specialized printer called a pneumatic feeding fused granule fabrication (FGF) printer was used. This printer allows for the direct printing of material granules, eliminating the need for filaments and resolving filament‐related problems. To evaluate the quality of the printed parts, tensile tests, dynamic mechanical thermal analysis (DMTA), and scanning electron microscopy (SEM) imaging were conducted. The printed parts showed desirable tensile properties (with approximately 3000% elongation at break and approximately 12 MPa tensile strength). Compression tests were also conducted on cubic structures with varied composition ratios and printing patterns such as grid, triangle, and honeycomb. The main purpose of this research was to explore the energy absorption capabilities of the printed blends. The results of our study showed that blending POE with LLDPE improved printability, tensile strength, energy absorption, and compressive properties. The blend with 50% LLDPE and honeycomb structure exhibited the best compressive and energy absorption properties.Highlights Blending of POE and LLDPE using melt mixing with three different blending ratios. Successful 3D printing with the fused granule fabrication technique. Investigating mechanical properties, microstructure, and thermal analysis. 125% increase in ultimate tensile strength by increasing LLDPE. Achieving the highest energy absorption for the 3D printed honeycomb structure.

Effects of TPU on the mechanical properties, fracture toughness, morphology, and thermal analysis of 3D‐printed ABS‐TPU blends by FDM

AbstractIn this paper, blends of ABS‐TPU with two different weight percentages of TPU were prepared using fused deposition modeling technology. The effect of adding TPU on the fracture toughness of ABS and mechanical properties was comprehensively studied. Tensile, compression, fracture toughness, and shear tests were conducted on the 3D‐printed samples. Thermal and microstructural analyses were performed using dynamic mechanical thermal analysis (DMTA), and scanning electron microscope (SEM). The DMTA results showed that adding TPU decreased the storage modulus and the glass transition temperature of ABS, as well as its peak intensity. The mechanical test results showed that adding TPU decreased the strength but increased the formability and elongation of the samples. Fracture tests showed that the addition of TPU decreased the maximum force needed for a crack to initiate. The force required for crack initiation decreased from 568.4 N for neat ABS to 335.3 N for ABS80 and 123.2 N for ABS60. The ABS60 blend exhibited the highest strength against crack growth, indicating that TPU can change the behavior of ABS from brittle to ductile. Shear test results and SEM images also showed good adhesion strength between the printed samples for all three specimens, indicating their good printability. Adding TPU resulted in a reduction in the size and number of voids and holes between the printed layers.Highlights Melt mixing, filament preparation, and 3D printing of ABS‐TPU blends. Investigation of mechanical properties, microstructure, and fracture toughness. Improved resistance to crack growth and elongation by adding TPU to ABS. Improving printability and reducing microholes in blends compared with ABS. Achieving a wide range of mechanical properties for various applications.

Microwave curing of modified benzoxazine resin/ethylene–propylene–diene monomer rubber/Kevlar composite

AbstractThe purpose of this paper was to show how modified benzoxazine resin/ethylene–propylene–diene monomer rubber/Kevlar composites are prepared. The compatibilization of polar benzoxazine resin and non‐polar EPDM was carried out by EPDM‐g‐MAH copolymer synthesized as a compatibilizer, and then, the microwave (MW) irradiation method and conventional thermal cure (CV) were used to cure this composite. The samples cured by both methods were evaluated and compared by differential scanning calorimetry analysis (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and thermo‐gravimetric analysis (TGA). Microwave curing significantly reduced the curing time, and the composites cured with MW irradiation had higher glass transition temperature (Tg), more uniform curing, higher cross‐link density, and more thermal stability than CV‐cured composites.Highlights Constructing BZ/EPDM/Kevlar thermal composite for use at high temperatures. Using modified resin to reduce curing temperature and improve final properties. Creating compatibility between non‐polar EPDM rubber and polar BZ resin. Investigating and comparing between thermal and MW curing of the composites.

Mechanical behavior of carbon/glass polypropylene hybrid composites

AbstractThis research investigates the influence of graphene and some additives on the mechanical behavior of polypropylene (PP). Anhydride maleic coupling agent (MAPP), graphene nanoplatelets (GNPs), and glass fiber (GF) were incorporated into the polymer matrix. The incorporation of MAPP and/or GNP significantly improved the affinity between the PP matrix and fibers while altering the surface morphology. More than 60% of the fibers showed a dimension lower than 0.5 mm. The tensile strength increased from 27.45 to 41 MPa for the neat PP compared to one of the composites. The strength modulus varied from 0.5 to 0.9 GPa. Mechanical tests showed that the addition of MAPP improved the tensile toughness (from 27.45 to 41 N mm mm−2) by 49%, while the GF increased tensile strength, albeit reducing elongation at break. The dynamic mechanical thermal analysis uncovered distinct behavioral variations among fiber‐reinforced samples, particularly in modulus peak differences. In rheological assessment, the presence of GF notably increased viscosity within certain shear rate ranges (at 100 [1/s], the viscosity goes from 200 to 300 Pa s to neat PP for some composites). This research highlights how chosen additives can influence a PP homopolymer's properties, offering useful insights for practical material processing and design.Highlights MAPP and GNP can increase PP and glass fiber interfacial bonding. Glass fiber raises tensile strength and decreases elongation. Sample with just GNP has a rougher surface, implying better energy dissipation. Glass fiber raises viscosity in the observed shear rate ranges. DMA demonstrates that MAPP and GNP have an influence on energy dissipation.

Morphological, compatibility, rheological and mechanical properties of graphene oxide/PLA/XNBR-g-GMA/XNBR: empirical and theoretical approaches

ABSTRACT The incompatible thermoplastic poly lactic acid/carboxylated acrylonitrile butadiene rubber (PLA/XNBR) was prepared, and the effect of graphene oxide (GO) as a reinforcement and glycidyl methacrylate (GMA)-grafted XNBR (XNBR-g-GMA) as a compatibilizer on the properties of PLA/XNBR blend was investigated in this research. The microstructure, mechanical behavior, thermal, rheology, and dynamic mechanical properties of PLA/XNBR composites were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), tensile test, and dynamic mechanical thermal analysis (DMTA). The incorporation of XNBR-g-GMA improved the compatibility of the PLA/XNBR blend phases, as confirmed by microstructure and DMTA analysis. The results of the mechanical properties showed that with an increase in GO content in the PLA/XNBR/XNBR-g-GMA matrix, there was a significant improvement in tensile strength, Young’s modulus, hardness, and impact strength. In order to validate the experimental mechanical and rheological results, various theoretical models were applied and a good agreement was observed between the theoretical and experimental data.

Mechanical, Rheological, and Heat Seal Properties of 1‐Octene Grafted Low Density Polyethylene Films

AbstractHeat seal and mechanical properties of 1‐octene grafted low density polyethylene films containing various concentrations of Dicumyl peroxide as the initiator and 1‐octene grafting agent is investigated through using experimental measurements. The results of differential scanning calorimeter (DSC) measurements revealed that the melting temperature shifts to higher values and the peak of the DSC curve becomes wider with the increase of 1‐octene concentrations. Thermogravimetric analysis (TGA) revealed a higher thermal stability up to 20 °C for 1‐octene grafted PE compared with neat LDPE alloy. The results of stress–strain measurements revealed that the 1‐octene grafted PE alloys has higher tensile strength in comparison with neat PE alloy and samples containing only DCP initiator. The results of heat seal analysis indicated that both DCP initiator and 1‐octene tended to offer a moderate increase peel strength of PE alloy. DMTA measurements for various grafted PE alloys show a higher damping factor in comparison with neat LDPE alloy. Rheological measurements indicated a higher storage modulus up to 25% and higher complex viscosity for grafted PE samples containing 1‐octene comonomer.

Biodegradable Nanocomposites Based on Blends of Poly(Butylene Adipate-Co-Terephthalate) (PBAT) and Thermoplastic Starch Filled with Montmorillonite (MMT): Physico-Mechanical Properties.

Poly(butylene adipate-co-terephthalate) (PBAT) is widely used for production of biodegradable films due to its high elongation, excellent flexibility, and good processability properties. An effective way to develop more accessible PBAT-based bioplastics for wide application in packaging is blending of PBAT with thermoplastic starch (TPS) since PBAT is costly with prices approximately double or even triple the prices of traditional plastics like polyethylene. This study is focused on investigating the influence of TPS/PBAT blend ratio and montmorillonite (MMT) content on the physical and mechanical properties and molecular mobility of TPS-MMT/PBAT nanocomposites. Obtained TPS-MMT/PBAT nanocomposites through the melt blending process were characterized using tensile testing, dynamic mechanical thermal analysis (DMTA), and X-ray diffraction (XRD), as well as solid-state 1H and 13C NMR spectroscopy. Mechanical properties demonstrated that the addition of TPS to PBAT leads to a substantial decrease in the tensile strength as well as in the elongation at break, while Young's modulus is rising substantially, while the effect of the MMT addition is almost negligible on the tensile stress of the blends. DMTA results confirmed the formation of TPS domains in the PBAT matrix. With increasing TPS content, mobility of starch-rich regions of TPS domains slightly increases. However, molecular mobility in glycerol-rich regions of TPS domains in the blends was slightly restricted. Moreover, the data obtained from 13C CP/MAS NMR spectra indicated that the presence of TPS in the sample decreases the mobility of the PBAT chains, mainly those located at the TPS/PBAT interfaces.

Acrylate composite polyurethane binder for steel bridge deck pavements: Process optimization by response surface methodology and microanalysis

AbstractTo better serve the steel bridge deck paving project, a novel room‐temperature curing acrylate composite polyurethane binder (APUB) was developed as a substitute for traditional asphalt binders. APUB was synthesized by the copolymerization of a custom‐made polyurethane prepolymer (BDO‐PU) and acrylate. Fourier transformed infrared and proton nuclear magnetic resonance spectroscopy analyses confirmed the presence of carbamate structures in prepolymer BDO‐PU. Utilizing tensile strength, breaking elongation and water absorption as optimization criteria, the response surface methodology was used to optimize synthesis process of APUB. The results showed that the optimized parameters for APUB synthesis include an isocyanate index (R) of 1.5, a mass ratio of methyl methacrylate to BDO‐PU of 1.1, and a curing agent content of 2.7%. These settings resulted in predicted values of 10.12 MPa for tensile strength, 123.85% for breaking elongation, and 0.075% for water absorption. Experimental validation demonstrated the consistency between the predicted and actual properties of APUB. Further microanalyses, including dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscope, confirmed APUB exhibits excellent component compatibility and glass transition temperatures suitable for bridge engineering environments. Overall, APUB demonstrates outstanding tensile properties, water resistance, low energy consumption, and potential applications in the steel bridge deck pavement industry.

Experimental Study and Seismic Response Evaluation of Chlorobutyl Rubber-Based Viscoelastic Dampers

Conventional viscoelastic devices often use high-damping elastomeric pads, typically made of patented formulations, that are bonded to steel plates. The response properties of these pads under cyclic shear deformations directly influence the load-deformation hysteretic response of the device. Chlorobutyl (CIIR) is a high-damping rubber commonly used in industrial applications. However, this study found that the damping properties of a typical CIIR rubber compound are insufficient for effective structural seismic mitigation at ambient temperatures above 0°C. The goal of this study was to develop a new composite of CIIR, referred to as modified CIIR, with improved damping properties and to compare its performance with that of the reference CIIR rubber. In the first phase of the experimental studies, the viscoelastic characteristics of the reference and modified CIIR rubber materials were evaluated using dynamic mechanical thermal analysis (DMTA) in tension mode. Prototype viscoelastic damper devices were then fabricated from both the reference and modified CIIR rubber materials and subjected to cyclic shear tests at room temperature and various loading frequencies. The results showed that the modified CIIR rubber exhibited significantly improved effective damping compared to the reference CIIR. The final component of this study involved investigating the seismic response of a 2D frame structure equipped with prototype dampers made from both reference and modified CIIR materials, using nonlinear time-history analyses. The analysis results indicated that the modified CIIR rubber can be effectively utilized in the seismic response mitigation of structures.