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Paper-based packaging materials are generally assembled using adhesives formulated with oil-based polymers. These adhesives make the recyclability of the materials more complex and may be the source of material contamination by mineral oil. In view of developing an adhesive-free process, the potential of ultrasonic compression was investigated in this study. 100% lignocellulosic papers were assembled using an ultrasonic welder dedicated to thermoplastic polymers. For papers containing lignin, the measured peeling strengths were equivalent to those achieved by hot-melt gluing, provided that the water content of papers was well adjusted. At the interface between bonded papers, the fiber network was dense and rather continuous. SEM examinations, 3D X-ray microtomography images, and temperature measurements suggested that the development of adhesion originated to a large extent from a thermoplastic welding mechanism: wood fiber polymers passed their glass transition temperatures, creeped and formed a matrix that coated fibers. Thus, ultrasonic welding appears as an efficient adhesive-free technique for assembling papers that are used in a broad range of packaging applications. [ABSTRACT FROM AUTHOR]

This research investigated the synthesis of thermoplastic polyurethane (TPU) with a hard segment content (HSC) of 30% weight. The chain extender, the polyols, and the diisocyanate utilized 1,4-butanediol (BDO), and the polycaprolactone diol (PCL-diol) with molecular weights of 2000, 4000, and 10,000 and isophorone diisocyanate (IPDI), respectively. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H-NMR), and X-ray diffraction (XRD) were used to examine the chemical microstructure and physical properties of PCL diol and thermoplastic polyurethanes (TPUs). The molecular weight of the PCL diol as soft segments affected the crystallinity and glass transition temperature (Tg) of TPUs. An increase in PCL diol molecular weight resulted in a reduction in elongation at failure and an increase in ultimate tensile strength. This study was conducted to investigate the permeability and the permselectivity of CO2 and N2 gases over pressure ranges (3 to 9 atm). It was determined that the gas permeability of each sample increased in response to an increase in the pressure of the supplying gas. An elevation in the molecular weight of PCL-diols in TPU samples resulted in a reduction in selectivity and an increase in CO2 and N2 gas permeability. Although IPDI is a non-aromatic cyclic diisocyanate with a significant impact on thermoplastic polyurethane phase morphology, the goal of this paper is to create a change in the molecular weight of PCL-diol and investigate the effect of molecular weight on the resulting morphology as well. [ABSTRACT FROM AUTHOR]

In this paper, statistical analysis and experimental methods are employed to study the hydrobromination of hydroxyl-terminated polybutadiene (HTPB) elastomer by 48% hydrobromic acid. The effect of three variables including time, temperature, and volume of acid, on the percentage of hydrobromination is investigated. The influence of these parameters and their interaction is checked through the analysis of variance and sensitivity analysis, and the optimum values for 10% hydrobromination are obtained 24 h, 30 °C, and 5.05 ml of the acid volume. A hydrobrominated resin is synthesized by applying optimal conditions for hydrobromination of 10% of double bonds. The results obtained from classical analysis and NMR show the amount of hydrobromination as 9.89% and 9.38%, respectively. The placement of the bromine atom in the compound is confirmed by ATR and NMR analysis. Also, DSC analysis shows that the glass transition temperature (Tg) of the hydrobrominated product increased by 2.86 °C compared to the initial HTPB. [ABSTRACT FROM AUTHOR]

Jelly glue made of gelatin is frequently used in the packaging industry. The purpose of this study is to determine whether starch and polyvinyl alcohol (PVA), which were introduced at a 1.0% concentration, could be used to develop with improvement in the performance properties of jelly adhesives that are being prepared. By examining viscosities at different temperatures, pH, water contact angles, differential scanning calorimetry (DSC), tensile strength on wood and setting speed observation on coated paper, and performing pencil hardness tests on films, the effect of adding starch and PVA as a binder on physical, thermal, and mechanical properties were studied. When starch and PVA were added to the jelly glue, DSC data showed a substantial rise in the glass transition temperature, which were further confirmed by film hardness testing. The addition of starch increased the adhesive's viscosities at different temperatures. When compared to an original sample, the tensile strength with starch increased by ~ 74% after 24 h of bonding in a dry environment. The jelly adhesive with starch showed increased in water resistance which was also validated from contact angle test. Unlike PVA-based jelly glue, the hydrogen bonding in starch and gelatin showed superior mechanical properties. This research discusses starch as a potential substitute for the development of jelly adhesive. The technique developed offers an easy and useful path to adhesives with increased water resistance and bonding strength by using starch as a binder. Ecologically sound, sustainable, and economically acceptable were the methods used to increase jelly adhesive's resistance to moisture. The study's overall finding highlights the superior and sustainable adhesive performance of jelly glue based on starch as a packaging adhesive. [ABSTRACT FROM AUTHOR]

In this paper, Polyethylene Terephthalate Glycol (PETG) has been used as a novel thermoplastic thermo-responsive Shape Memory Polymer (SMP) with biocompatibility, excellent printability, cost efficiency, and transparency for the 3D/4D printing of porous structures by material extrusion. The high deformability of PETG allows for programming without an increase in temperature or the need for additional operations. This enabled the use of PETG for the Cold Programming (CP) of ordered porous shape memory structures, made possible by material extrusion printing technology. The porous samples were printed employing three patterns and two porosity percentages. The programming operation was performed at ambient temperature by applying different amounts of pre-strains under constrained and unconstrained compression modes. The constrained test was conducted using a mandrel and a matrix for exerting pure volume reduction (pure packing). The shape recovery test was accomplished above the glass transition temperature (Tg), and the fixity and recovery ratios were recorded. Employing 3D printing provided the ability to manufacture porous thermoplastic SMP structures with highly controllable pores geometry and sizes for different porosity percentages. The results showed that the combination of the uniform strain distribution in the porous structures with the help of the 3D printing process and CP on the new PETG SMP makes it possible to achieve high deformation in the glassy region, resulting in a complete shape recovery for two lozenge and vertical patterns. Among all specimens, constrained specimens by horizontal pattern had the highest fixity ratio of 90.7%. However, low fixity ratios in CP can be justified considering the existence of two stages of spring-back and structural relaxation after unloading, resulting from the elastic and viscoelastic behavior. Increasing Infill Density (ID) along with the constrained test (pure packing) improved the shape fixity. The existence of higher mechanical constraints and harsher localized deformation are speculated to be the case for this observation. Applying higher deformations (40 to 80%), for both designed tests, brought about a weakness in the shape memory performance, while it improved for 100% volume reduction. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanical response and the mechanisms of failure of an ultra-high molecular weight polyethylene under service at cryogenic temperature. The service temperature T s being about 50 ∘ C below its glass transition temperature T g , the study focuses on the experimental techniques to determine both the glass transition temperature T g and the ductile–brittle transition temperature (DBTT). T g was estimated by dynamic mechanical thermal analysis (DTMA) and contrasted with the glassy–rubbery transition defined by using the Young's modulus issued from monotonic tensile tests on smooth specimens at room and low temperature and various cross-head speeds. Concerning the DBTT, two estimators of the transition, based on the fracture surface and the up-to-failure data, were studied. An operating diagram (temperature/cross-head speed) including the probability of ductile failure and both the rubbery and glassy domains is proposed. This diagram aims at finding an optimal compromise of the material response combining stiff versus soft with brittle versus ductile behaviour. [ABSTRACT FROM AUTHOR]

Polyurethanes, an important class of polymers, are used extensively for preparing various apparel, shoesoles, etc. This paper reports that polyurethanes could be prepared conveniently after blocking the precursor molecule toluene diisocyanate (TDI)with 4-bromo-1H-pyrazole to form blocked toluene diisocyanate (TDI). The blocked adducts were characterized by FTIR, NMR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and CHNS analysis. Particularly, spectroscopic analysis was used to confirm the complete blocking. The DSC thermogram showed that the blocked adducts deblock at 238 °C, regenerating TDI and blocking agent 4-bromopyrazole. At 238 °C, regenerated TDI reacted with polyolsof different molecular weights to form polyurethane under solvent-free conditions. The polyurethanes were further characterized by FTIR, NMR, thermogravimetric analysis, differential scanning calorimetry, and contact angle study. FTIR study shows that there is no peak at 2250–2270 cm−1. So it confirms the absence of NCO peaks. Contact angle measurements of various polyurethanes showed the values in the ranges of 27–50 °C, indicating generally hydrophilic natures of samples. DSC thermogram indicates the presence of glass transition temperature of synthesized polyurethanes at − 30 to − 40 °C. Viscosity measurements of polyurethanes in chloroform at different temperatures indicated decrease in viscosity at higher temperature. [ABSTRACT FROM AUTHOR]

Leaf spring is often used in commercial vehicles' suspension systems to ensure ride comfort and support dynamic wheel loads. This paper studies the thermal failure mechanism of sliding composite leaf springs. The thermal failure temperature and thermal failure mode were investigated by the bench test. The results show that when the temperature exceeds the glass transition temperature (Tg point 115 °C) for 30mins, cracks will appear around the bolt hole of the composite body. The damaged area expanded with the continuous increase in temperature. When the gap (between the fiber and the resin) grows to a stable stage, the failure temperature of the composite body becomes stable. The crack propagates first longitudinally first and then transverse. When the transverse crack is transformed into a sharp fracture, the spring may fail with decreased stiffness. This study can better understand the performance of composite leaf springs working at high temperatures and provide an effective reference for the study of the spring's service condition. [ABSTRACT FROM AUTHOR]

This paper presents the investigating results of the effect of different nanofillers like unmodified and modified halloysite nanotubes (HNT), nanosilica, and nano-titanium on the mechanical and thermal properties of polyetherimide (PEI)/silicone rubber-based nanocomposites. The PEI/silicone rubber nanocomposites reinforced with different nanofillers at 3 phr were prepared with the aid of a co-rotating twin-screw extruder. The developed nanocomposites were compared by various mechanical properties, thermal properties, and dynamic mechanical analyses. Morphological properties have been visualized by scanning electron microscope. The results obtained depict that the tensile strength, tensile modulus, storage modulus, and glass transition temperature have significantly increased with the incorporation of modified HNT at 3 phr loading due to the interfacial and inter-tubular interactions between HNT and polymer matrices. The enhancement in glass transition temperature may be because of the restricted movement of the polymer chains by the nanofillers, and the formation of HNT zig-zag structures is the main reason for the improvement of various properties. The bridging effect of modified nanosilica at the blend interface may also be responsible for the enhancement of elongation at break and impact strength which is higher than other nanofillers. [ABSTRACT FROM AUTHOR]

Transition temperature is significant in determining applications of phase change materials. In this paper, PEG2000 and PEG4000 were used as soft segments and MDI and 3,3ʹ-Dichloro-4,4ʹ-diaminodiphenylmethane (MOCA) were used as hard segments. Several polyurethane solid–solid phase change materials (PUSSPCMs) were synthesized by adjusting the mass ratio of PEG4000 and PEG2000. Based on the differential scanning calorimeter test, this paper studied the relationship between the mass ratio of PEG2000 and the phase transition temperature. The influence mechanism of phase change temperature was revealed from molecular structure, crystallization properties, and surface morphology. Furthermore, PUSSPCMs were tested for leakage and the thermal stability. The results showed that the synthesized PUSSPCMs had no liquid leakage during the heating process. There was a good linear relationship between the mass ratio of PEG2000 and phase transition temperature. The thermal decomposition onset temperature was above 230 °C. [ABSTRACT FROM AUTHOR]

The manufacture of flexible devices is of immense interest due to their eco-friendliness, economic prospects and wide range of applications in biocompatible devices. Therefore, this paper reports the characterization and properties of chlorinated natural rubber (Cl-NR)/polyindole (PIN) blend with different contents of nickel oxide (NiO) nanoparticles. The formation of blend nanocomposites was analysed by FT-IR, UV spectroscopy, XRD, FE-SEM, DSC and TGA. The FT-IR and UV spectra proved the effective interfacial interaction between nanoparticles and the blend matrix, with a shift in UV peak intensity with the attachment of NiO at 433 cm−1. The XRD pattern revealed the regular arrangement of the blend matrix due to the presence of nanofiller, resulting in the semicrystalline structure of the composite system. The SEM micrographs revealed a homogeneous distribution of NiO in the blend matrix. The increased degradation temperature in the TGA demonstrated the enhanced thermal stability of the NiO-filled Cl-NR/PIN blend. DSC results showed that the glass transition temperature of the composite increased with NiO content in the blend matrix. The dielectric properties and AC electrical conductivity increased significantly with increasing temperatures, as well as with the addition of nanoparticles up to 5 mass % loading. The inclusion of NiO improved the tensile strength and hardness while reducing the elongation-at-break of nanocomposites. The blend nanocomposite with enhanced thermal stability, glass transition temperature, tensile strength, AC conductivity and dielectric properties enables them to be used in highly flexible electronic applications where traditional elastomeric materials fall short. [ABSTRACT FROM AUTHOR]

Nowadays, the rapid development of industrial technology is putting a great demand for high-performance epoxy resin. Traditional bisphenol A epoxy resin (DGEBA) is facing great challenges from both the perspective of human health and the needs of cost reduction under the background of oil resources shortage. Therefore, it's important to find appropriate substitutes for DGEBA. In this paper, a trifunctional epoxy resin (DPA-E) was prepared using a simple two-step method with diphenolic acid and epichlorohydrin. It was interesting that the DPA-E, cured by 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane (DMDC), showed the similar properties as DGEBA except for curing temperature, glass transition temperature, and thermal expansion properties. The gel temperature for DPA-E/DMDC was as low as 29 ℃, which was obtained from curing kinetic study. Even for curing temperature of DPA-E/DMDC was also relatively low (Tp = 83 ℃). Even so, the glass transition temperature of this system was as high as 239 ℃, which was 24% higher than that of DGEBA/DMDC (Tg = 193 ℃). Furthermore, DPA-E/DMDC showed a lower thermal expansion coefficient, especially at elevated temperature (> 150 ℃). Therefore, this kind of new epoxy resin might have a very hopeful future in many important areas including aerospace and microelectronics. [ABSTRACT FROM AUTHOR]

In this article, three new poly(1,2,3-triazolyl-benzenesulfonamide)s (4-6) were synthesized from the new molecule 4-azido-N-(prop-2ʹ-yn-1ʹ-yl)benzenesulfonamide (3). The synthesis and step-growth click polyaddition reaction of a new AB-type monomer containing terminal alkyne and azide groups were described. Copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) and Huisgen click polymerization were performed to prepare sulfonamide, a derivative of poly(1,2,3-triazole)s. The CuAAC polymerization regioselectively led to 1,4-disubstituted triazole ring and hence to a stereoregular polymer. In contrast, the thermal polymerization also produced 1,5-disubstituted triazole units. The structure of the new poly(1,2,3-triazolyl-benzenesulfonamide)s (4-6) obtained from (4-azido-N-(prop-2ʹ-yn-1ʹ-yl)benzenesulfonamide) were characterized by FTIR, 1H-, and 13C- NMR spectroscopy. The resulting polymers had weight-average molecular weights in the 7,700-58,650 range and were determined by Gel Permeation Chromatography (GPC). The resulting polymers 4, 5 and 6, lossing about 50% of their weights, showed a decomposition temperature of 406, 474, and 451 °C in a nitrogen atmosphere, respectively. The glass transition temperature of all polymers were at 128 °C. In addition, the surface morphology was studied via Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). This paper is dedicated to the 100th Anniversary of the Republic of Türkiye. [ABSTRACT FROM AUTHOR]

There has been a broad demand for materials with high thermal stability and low dielectric constant in the field of microelectronic devices and communication technology. In this paper, a novel fluorinated poly(aryl ether) (FPAE) was prepared by SN2 nucleophilic polycondensation. FPAE was demonstrated to possess a favorable dielectric constant of 2.68 at 1 MHz and its dielectric relaxation behavior at various temperatures and frequencies was analyzed. The resin performed excellent thermal stability and heat resistance, with a 5% mass loss temperature of 514 °C and a glass transition temperature of 260 °C. FPAE exhibits high solubility in N, N-dimethyl-formamide, acetone, ethyl acetate and other solvents. Excellent solubility gives FPAE good film formation and processability. The tensile strength and tensile modulus of FPAE were 67.0 MPa and 2.1 GPa, displaying decent mechanical properties. Attributed to the characteristics of the fluorine atoms, FPAE demonstrated a certain hydrophobicity with a water contact angle of 97.9°, as well as satisfactory water absorption (0.17%) and a low surface energy of 21.71 J/mm2. These data indicate that FPAE is expected to be used as low-dielectric material in microelectronics and communication technology. [ABSTRACT FROM AUTHOR]

In the present paper, the study of amorphous-crystalline transformation in (Se80Te20)94−x Ge6Bix (x = 0, 1, 2, 4, 6, 8, 10 and 12 at.%) chalcogenide alloys has been done using non-isothermal differential scanning calorimetry (DSC). Characteristic temperatures indicate that the samples with x = 1 at.% and x = 6 at.% can be considered as a critical configurations at which the system becomes a chemically ordered alloy. Kissinger and Moynihan approaches which utilized dependence of glass transition temperature (Tg) on heating rate (α) are used to deduce activation energy of glass transition (Eg). Crystallization process is characterized by various kinetic parameters such as activation energy and frequency factor deduced using different methods. Dietzel, Hruby, Saad and Poulin criteria are employed to assess glass forming ability and thermal stability of investigated alloys. The alloy with x = 12 at.% of Bi content has highest ∆T confirms maximum thermal stability, further validated from the values of Hruby parameter (Kgl) and thermal stability parameter (S). The fragility index infers that the composition studied in the present study is made from strong glass forming liquids. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymer (CFRP) composites are widely used in many industries due to their outstanding multifunctional properties. The durability and performance of these materials depend on their mechanical properties and fiber/matrix interface. A good interface ensures not only efficient load transfer but also long-term safety. Studies demonstrate that composites are affected by moisture, ultraviolet irradiation, and cyclic temperature variations. This review focuses on the performance of CFRP at high and cryogenic temperatures. There is a critical need to characterize and predict composite interfacial performance under different temperature fluxes. This paper presents an overview of the fiber-matrix interface at different temperatures and strain rates. First, interfacial mechanisms, mechanical tests, physical and chemical characterization techniques, and numerical simulations are introduced. Then, the effect of high temperatures, low temperatures, and strain rates on the composite's interface are discussed. Interfacial adhesion is quantified utilizing different experimental techniques, including Iosipescu, short beam shear, fiber pullout/pushout, and fragmentation tests. While these report different interfacial strength values, factors that affect this variability are studied. High temperatures greatly decrease the interface strength of polymer matrix composites (PMCs) at temperatures above the resin's glass transition temperature (Tg). Cryogenic temperatures create micro-cracks between the fiber and polymer matrix. While mechanical tests, morphology observations, and chemical analysis help explain interfacial debonding after testing, these cannot explain the debonding process during testing. Simulation techniques add to the fundamentals of mechanics and predict the interfacial debonding process, and the methods to predict interfacial failure in extreme environments are discussed. [ABSTRACT FROM AUTHOR]

Metal-polymer composites are constantly developed and applied for numerous purposes due to some irreplaceable and adjustable properties like thermophysical, tribological or mechanical. The differences of mechanical and thermal conductivity between metal and polymer materials lead to different removal behaviors from traditional homogeneous materials. The improvement of machining surface quality becomes an urgent problem to be solved in expanding its application. In this work, material removal characteristics of copper particle-filled PTFE composites (Cu/PTFE) material in cutting process were investigated. Dynamic mechanical analysis (DMA) experiments were applied to investigate how the temperature affected the mechanical characteristics of the Cu/PTFE materials. Then the material removal mechanism was studied by simulation and experiment. The results revealed that there are three simultaneously exist removal modes of the Cu/PTFE material, depending on the position of the particles relative to the cutting edge and the cutting temperature. An important finding is that the difference between the actual roughness and the theoretical roughness based on the tool envelope model is linearly related to the cutting temperature. This is mainly due to the approximately linear decrease of the storage modulus with temperature. With rising temperature, the material's storage modulus exhibited a tendency to decrease and a poorer mechanical loss at glass transition temperature was also certificated. The material removal characteristics of the cutting Cu/PTFE surface and its underlying mechanism revealed in this paper are instructive for determining the machining parameters to improve the surface quality. [ABSTRACT FROM AUTHOR]

Synthesizing nanofillers from bioresources in a cost-effective way is a practical approach to manage waste and circular economy. This paper highlights the preparation of nano-calcium carbonate (NCC) from dead coral exoskeleton by a simple hydrothermal method. The NCC was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface area analysis. NCC with a particle size of 10-20 nm was obtained by this method. A two-roll mill was used to make the nanocomposites of acrylonitrile-butadiene rubber (NBR) with NCC at various filler concentrations (3, 6, and 9 phr). The cure, physico-mechanical, thermal, swelling, and dynamic properties of the composites were investigated. The mechanical and technological properties of NBR were improved by the incorporation of NCC. About 89% increase in tensile strength was observed with the inclusion of 3 phr NCC to the NBR-Gum. The thermal stability of NBR (Tmax) was increased from 450 °C to 455 °C by the addition of 3 phr NCC. Furthermore, the 9 phr NCC composite showed an 18% lower swelling index and 27% higher crosslink density compared to NBR-Gum. The glass transition temperature of NBR increases from -4.70 to -3.29 °C with the addition of 3 phr NCC. The highest Payne effect was observed for NBR-NCC 9 phr composite, indicating effective filler-filler network formation. [ABSTRACT FROM AUTHOR]

In this paper, a series of novel carbazole-based polysiloxane oligomers: P(CzVinyl11Siloxane2), P(CzVinyl21Siloxane2), and P(CzVinyl11Siloxane3) with high refractive index (RI) containing the linear and/ or branched structures with vinyl and carbazole reactive moieties have been presented to the literature for optoelectronic applications. The polysiloxane oligomers were synthesized by an acid-catalyzed sol–gel condensation reaction of alkoxysilane monomers (carbazole-dimethoxysilane (Cz-2SiOCH3) and vinyl-(di- or tri-methoxy)silanes (VMDMS or VTMS)) in the presence of trimethylmethoxysilane (SiMe) after a photoinitiated thiol-ene reaction was performed to obtain the compound Cz-2SiOCH3. The structural confirmations were made using FT-IR, 1H NMR, and 13C NMR spectroscopies. In addition, a 29Si NMR study was performed to elucidate the nature of the siloxane structure of P(CzVinyl11Siloxane2). The refractive indices of the polysiloxane oligomers were between 1.6028 and 1.5923 as high values by varying the linear or branched structures. DSC analyzes revealed that the glass transition temperatures of P(CzVinyl11Siloxane2), P(CzVinyl21Siloxane2), and P(CzVinyl11Siloxane3) were -11 °C, -5 °C and -39 °C, respectively. Then, the polysiloxane oligomers were photopolymerized and their structural changes were observed by spectroscopic techniques. The photopolymerized polysiloxane oligomers with maintained and/ or enhanced refractive index values (between 1.6132 and 1.5719) showed very good transparency between 86.11% and 81.33% at 600 nm by the spin coating films. The novel carbazole-based polysiloxane oligomers would be useful chemical products or intermediates for the development of optical materials applied in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Excellent thermal and mechanical properties and high chemical resistance with low shrinkage of epoxy resins open a wide window of various industrial applications, including coatings, paints, adhesive, etc. Despite their excellent properties, epoxy resins are brittle and have a low resistance to the initiation and growth of cracks. To overcome this drawback, different kinds of reinforcements, including liquid rubbers, core–shell rubber particles, dendritic polymers, block copolymers, thermoplastics, rigid particles, etc., have been used to improve the fracture toughness of epoxy resin systems. This paper briefly introduces each reinforcement separately and mainly presents an in-depth review of the progress of the last decade in the field of toughening of epoxy resins using core–shell rubber particles. This review paper also refers to the results of the research papers published on the effect these rubber particles on the mechanical properties of epoxy resins, as well as explains different toughening mechanisms of epoxy resins. Researchers first focused on the use of core–shell rubber particles containing different cores and shells. They then used core–shell rubber particles along with rigid fillers such as silica to offset the slight diminish in mechanical properties, as well as the glass transition temperature. In recent years, some research teams have used core–shell rubber particles and block copolymers simultaneously and have achieved fascinating results. [ABSTRACT FROM AUTHOR]

Poly(silylene arylacetylene) resins have good mechanical properties and excellent heat resistance. In this paper, bis(ethynylphenoxy) diphenylsulfone (BEPS) was synthesized by Williamson and Sonogashira reactions. Furthermore, a series of poly(silylene ethynylenephenoxy diphenylsulfone) (PSEF) resins were synthesized from BEPS and various silanes with different substituents (-H, -CH3, -C6H5, -CH=CH2) through Grignard reagent method. The structures and properties of synthesized resins were characterized. The properties of carbon fiber-reinforced PSEF (T300/PSEF) composites were measured. The results indicate that the PSEF resins demonstrate high mechanical properties with excellent heat resistance and the substituents on the main chain of PSEF resin would slightly affect the thermal properties of the resin, but greatly affect the processing and mechanical properties. The PSEF with phenyl substituent (P-PSEF) shows the best processability and mechanical performance with a Td5 of 437 °C. The T300/P-PSEF composite has a flexural strength of 620.9 MPa at room temperature and no glass transition in the range of rt ~ 450 °C. [ABSTRACT FROM AUTHOR]

The epoxy composite cured by imidazole has better heat resistance. In this paper, the heat-driven mass loss process of epoxy resin matrix and carbon fiber epoxy laminate cured by 2E4MI, a kind of imidazole, were investigated by thermogravimetric analysis at different heating rates under nitrogen and air atmosphere. It was observed that the pyrolysis reactions of epoxy resin cured with imidazole and its carbon fiber epoxy laminate consist of one step in the nitrogen atmosphere, but in air atmosphere, their pyrolysis reactions consist of three and four steps, respectively. The glass transition temperature of 2E4MI cured epoxy resin was obtained around 143–150 °C and the variation of specific heat capacity with temperature was obtained between 20 and 230 °C. Furthermore, kinetic parameters for the pyrolysis of the samples were estimated using Kissinger and FWO method. The apparent activation energy and the apparent pre-exponential factor of 2E4MI cured epoxy resin were obtained around 165 kJ mol−1 and 4.85 × 108 in nitrogen, and these values in air were less. To carbon fiber epoxy laminate, these values were around 166 kJ mol−1 and 6.68 × 108 in nitrogen. It was shown that the thermal performance of the 2E4MI cured epoxy resin determined the thermal performance of the carbon fiber laminate to a large extent. So, the use of curing agent in epoxy resin indirectly determines the thermal properties of composites. [ABSTRACT FROM AUTHOR]

Epoxidation modification is an effective method to improve compatibility and dispersion of polar fillers in styrene-butadiene rubber (SBR). However, large amount of organic solvents used in common process of epoxidation modification not only increases cost, but also poses threat to environment. In this paper, epoxidized styrene-butadiene rubber (ESBR) with different epoxy degrees were synthesized by direct epoxidation modification of styrene-butadiene latex utilizing in-situ generated peroxyformic acid. Meanwhile, the effects of different experimental conditions on epoxy degree of ESBR were investigated. The spectra of 1H NMR and FT-IR indicated that polar epoxy groups were successfully introduced into molecular chain. Thermal analysis showed that the glass transition temperature Tg increased with the increase of epoxy degree of ESBR, and the thermal stability before and after modification did not change significantly. The optimal process for ESBR was also determined with response surface analysis. [ABSTRACT FROM AUTHOR]

In this paper, a cyclotetrasiloxane modified with epoxy resin was synthesized via hydrosilylation with 1, 3, 5, 7-tetramethylcyclotetrasiloxane (D4H) and 4-vinyl-1-cyclohexane 1, 2-epoxide (VCHO). The structure of tetramethylcyclotetrasiloxane modified with cyclohexane epoxide (D4H–VCHO) was characterized by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC). The effects of feeding methods, feeding ratios, catalyst dosages, reaction temperature and reaction time on the products were investigated. After 4-h reaction with 8 ppm catalyst at 90 °C, D4H–VCHO was obtained with an epoxy value of 0.521 and a refractive index of 1.4920. Then, with 4-methylhexahydrophthalic anhydride as a curing agent and tetrabutylammonium bromide as a catalyst, the obtained D4H–VCHO was cured at 90 °C for 1 h and then 120 °C for another hour. The cured products showed high light transmittance, strong thermal stability, suitable hardness and low water absorption. The glass transition temperature of cured materials was 151.6 °C, indicating the improvement of flexibility. In addition, the introduction of epoxy groups greatly enhanced the adhesion of silicone resins to substrates. The results demonstrated that the epoxy-modified silicone materials could be applied as LED packaging materials. [ABSTRACT FROM AUTHOR]

In this paper, thermal properties, atomic-scale structure, and molecular dynamics (at ambient and high pressure) of native melatonin (MLT) and its partially-deuterated derivative (MLT-d2) have been investigated. Based on infrared spectroscopy, it was shown that treating MLT with D2O causes the replacement of hydrogen atoms attached to the nitrogen by deuterium. The degree of such substitution was very high (> 99%) and the deuterated sample remained stable after exposure to the air as well as during the melting and vitrification processes. Further calorimetric studies revealed the appearance of a peculiar thermal event before the melting of crystalline MLT-d2, which was assigned by the X-ray diffraction to a local negative thermal expansion of the unit cell. Finally, the high-pressure dielectric experiments indicated a few interesting findings, including the variation in the shape of the structural relaxation peak during compression, the difference in the pressure evolution of the glass transition temperature, and the temperature dependence of activation volume for both MLT species. The variations in these parameters manifest a different impact of the compression/densification on the dynamics of hydrogen and deuterium bonds in the native and partially-deuterated MLT, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the modified h-BN coating was coated on the prepreg sheets; then, the carbon fiber/epoxy composite laminates were prepared by compression molding. The through-thickness thermal conductivity, mechanical and thermomechanical properties of the laminates were studied, respectively. The results show that h-BN particles, which are flaky shape with a diameter of about 0.6 μm and thickness of about 70 nm, have been evenly incorporated into the composites, and the thermal stability, through-thickness thermal conductivity, impact strength and glass transition temperature (Tg) of the composites are improved accordingly. When the BN content is 10 m%, the initial thermal degradation temperature (Tinitial) of the prepreg is 370 ℃, which is 10 ℃ higher than that of unmodified prepreg. When the BN content is 7 m%, the thermal conductivity of the laminates reaches 0.9 and 1.0 W·m−1·K−1 at 25 and 100 ℃, respectively, which are 114% and 111% higher than that of pure laminate. When the content of BN is 5 m%, the impact strength of the laminate reaches the highest value of 225 kJ·m−2, which is 15.4% higher than that of pure laminate. BN particles form a dense heat conduction network, thus delaying the thermal degradation of the resin and improving the thermal conductivity. This study provides a facile path to fabricate composite laminates with the integrated structure and function. [ABSTRACT FROM AUTHOR]

Cumulative density-relaxation data from the literature (following a thermal quench or during a constant rate of cooling) for polystyrene are analyzed. Consideration is given to four well-known models for the relaxation time as a function of temperature and fictive temperature, starting with the seminal modeling proposed by Tool in 1946. Among the numerous experimental results, those presented by Greiner & Schwarzl in 1984 are the most extensive, including their notable result that, under constant-cooling rate, the apparent glass-transition temperature (Tg,apparent) varies linearly with the log of the cooling rate (qc). In the present paper, it is established by detailed numerical analysis that Tool's model is the one which replicates this linear dependence between Tg,apparent and log qc. In turn, this implies that the temperature dependence of the equilibrium relaxation time (or the temperature shift factor) is purely exponential below the glass-transition temperature. This behavior is also shown to describe available experimental data in the literature (all below the nominal glass-transition temperature) for the stress relaxation of polycarbonate and the dielectric compliance of polyvinyl acetate. [ABSTRACT FROM AUTHOR]

Lignin is obtained as a by-product in the manufacturing of cellulose pulp for paper. Usually, it is used as internal fuel in this process and, in general, it is not recovered for use as a chemical product. Lignin is the second more abundant natural polymer, and it represents an enormous renewable raw material source. It is well known that epoxy resin is extensively used thanks to its high versatility and its good thermal and mechanical properties. However, most of the commercial epoxy resins use bisphenol A as a precursor, which has been reported to have estrogenic activity. In this work, up to 50 wt% of lignosulfonic acid sodium salt (lignin) has been added to epoxy resin to reduce the amount of both hardener and resin and make a green epoxy adhesive. The effect of lignin on curing kinetics, glass transition temperature and thermal conductivity was explored. The novelty of this work is the use of this green adhesive for cork. It was found that the addition of lignin improves adhesion with cork thanks to the affinity of these materials, and a high percentage of this component produces modifications on the curing process. Besides, with the addition of lignin, the bisphenol A concentration is reduced. [ABSTRACT FROM AUTHOR]

Thermal spraying is the most important coating technology for depositing advanced ceramic coatings which have been widely applied to different industrial fields for materials protection and various physical–chemical functions. The adhesion and cohesion are of primary importance for the successful applications of ceramic coatings. Three bonding mechanisms contribute to the enhancement of the adhesion and cohesion, including mechanical interlocking, physical bonding and chemical bonding. It is still challenging to achieve chemical bonding in thermally-sprayed coatings. In this paper, the main factors influencing the bonding formation during thermal spraying of ceramic coatings, including spray particle parameters and substrate parameters, are examined from splat formation to coating formation to find solutions to the above challenge. The research progress on splat formation revealing characteristic dynamic parameters relating to the bonding formation kinetics will be briefly presented for the key factors determining splat shape, flattening time, solidification time, cooling rate, interface temperature, and transient dynamic contact pressure during flattening. The typical coating lamellar structure features with limited intersplat bonding less than one-third for refractory ceramics, which dominate the coating properties and performance based on theoretical relationships between the microstructure and properties, are presented. The effects of spray particle parameters on the intersplat bonding reveal that the bonding ratio is increased with increasing particle temperature, but decreased with increasing particle velocity which benefits only the mechanical bonding. Most importantly, recent studies have revealed that the liquid splat–substrate interface temperature higher than the glass transition temperature of spray materials is a necessary and sufficient condition for splat bonding formation. A critical bonding temperature concept is proposed to control the intersplat bonding formation by controlling the substrate preheating temperature. The critical bonding temperature is related to the melting point of spray materials. A model is proposed to understand the effect of the interface temperature on the bonding formation of impacting liquid splat and the bonding mechanisms. The condition for certain ceramic spray materials to form a bulk-like dense coating with the intersplat interface completely bonded becomes well understood. Moreover, the effect of metal substrate oxide scale control on the adhesion reveals that an adhesive strength higher than 100 MPa can be achieved for plasma-sprayed ceramic coatings. The excellent bonding at the interface between the splat and the oxide scale pre-oxidized on the metal substrate can be also explained by the bonding formation model. It becomes possible that, through both the controls of the pre-oxidation and the deposition temperature, all the interfaces in the ceramic coating with the metal/oxide-scale/splat/splat system can be bonded by chemical bonding to achieve an excellent load-bearing ceramic-coating system. [ABSTRACT FROM AUTHOR]

Asphaltenes tend to aggregate to nanoparticles or clusters in crude oil and solvents over a wide concentration and temperature range. In the present paper, asphaltenes extracted from the base asphalt was used as a filler to introduce into epoxy resin. The microstructure and evolution of asphaltenes aggregation in the epoxy resin were observed using laser scanning confocal microscopy. Furthermore, the effect of asphaltenes on the viscosity, dynamic mechanical behavior, thermostability, mechanical properties of epoxy resin was evaluated by Brookfield rotational viscometer, dynamic mechanical analysis, thermogravimetric analysis and universal testing machine. The presence of asphaltenes increased the viscosity of the neat epoxy during all stages of cure reaction. The viscosity of epoxy/asphaltenes composites increased with the filler concentration. Fractal asphaltenes aggregation formed in the composites with 1 mass% asphaltenes. Network microstructures of asphaltenes aggregation appeared in the epoxy phase with a further increase of asphaltenes content. Moreover, the increase of asphaltenes loading resulted in denser network microstructures in the epoxy matrix. Aggregation evolution revealed that asphaltenes particles redispersed evenly in the epoxy resin in the form of some aggregates at the beginning of curing. During the cure reaction of epoxy, asphaltenes aggregates started to agglomerate and grow to network microstructures. The presence of asphaltenes led to the enhancement of the storage modulus of the neat epoxy at the rubbery stage. The glass transition temperature (Tg) of the epoxy composites slightly increased with the increase of asphaltenes loading. The epoxy composite with 5 mass% asphaltenes had higher Tg than the neat epoxy. The inclusion of asphaltenes had a negligible effect on the damping properties and thermal stability of the neat epoxy. The aggregation and heterogeneous dispersion of asphaltenes resulted in the decrease of the tensile strength and elongation at break of the neat epoxy. However, the inclusion of asphaltenes significantly enhanced Young's modulus of the neat epoxy. Young's modulus of the neat epoxy was increased by more than fourfold with the addition of 5 mass% asphaltenes. [ABSTRACT FROM AUTHOR]

In this paper, the polymerization of acrolein (A) via UV-mediated atom transfer radical polymerization (ATRP) is reported. The optimization of the experimental conditions of the polymerization is investigated, and it shows that dimethyl sulfoxide as solvent, ethyl 2-bromoisobutyrate (EBIB) and fluorescein (FL) as catalyst, and [A]0/[EBIB]0/[FL]0 = 200/1/0.1 in the period of 5 h at 47 °C are suitable conditions for the reaction. In this way, the yield of the polymer is 24.5%. The glass transition temperature and melting point of polyacrolein characterized by differential scanning calorimetry are 115.5 °C and 165.7 °C, respectively. At low conversion, the polymerization conforms to be the first-order kinetics reaction. The dependence of polymerization on light source is proved by "on/off" light source experiment. In short, this study opens up a new way for the ATRP of acrolein, and the polyacrolein with abundant aldehyde groups can be used in the fields of biomedical labeling, immobilization carrier and adsorption of organic amines. [ABSTRACT FROM AUTHOR]

The present paper aims to compare study the effect of porosity and degree of crystallinity on both quasi-static and fatigue behaviours of PA6 and PA12 specimens obtained by the fused filament fabrication (FFF). The glass transition and melting temperatures were measured complementary to understand better the process. Fatigue analysis is here described in visco-elastic domain of material. The results highlight that the mechanical and fatigue properties of PA 12 are better than those of PA6, in spite of almost amorphous state of PA12. Besides, porosity did not reveal the expected influence on these properties. The obtained results are also compared with conventional techniques given by the literature review. [ABSTRACT FROM AUTHOR]

This paper describes the research on the electrical ageing mechanism of the resin-rich molding (RRM) insulation by the dielectric response method for large generator. The dielectric properties of the RRM insulation materials with different ageing time were measured and analysed by dielectric temperature spectrum, frequency-domain spectrum (FDS) and thermally stimulated depolarization current (TSDC). The microscopic properties of the main insulation material were also analysed by scanning electron microscope and dynamic mechanical analysis. The results of the FDS measurements showed that the dielectric loss factor tan δ and the real part ε of the complex dielectric constant of the main insulation material increased significantly in the frequency range of 10−2–10 Hz as the ageing time increased; the fitting results of the double relaxation HN (Havriliak–Negami) model indicated that DC conductivity and interfacial polarization increased by the electric ageing effect in the main insulation. When the test temperature exceeded the glass transition temperature, the relaxation process of turning-direction polarization changed in the main insulation system; the TSDC tests indicated that the energy levels of the deep and shallow traps were slightly reduced during the main insulation's ageing, but the number of traps increased; therefore, the ability of capturing and releasing charges was enhanced in the main insulation. [ABSTRACT FROM AUTHOR]

In this paper we report the structural, thermal, microstructural and infrared transmission properties of iodine doped (Ge20Se18Te62)100 – xIx (where x = 0, 8) chalco-halide glasses. The density of the specimen has been calculated experimentally. Differential thermal calorimetry shows a single glass transition temperature but two crystalline peaks. The role of annealing (503 and 593 K for 2 h) has also been taken into account to investigate the structural, microstructural, and infrared transmission properties. X-ray diffraction study has revealed that on annealing there is an origin of hexagonal Te and orthorhombic GeSe2 microcrystals which are further supported by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The effects of dioctyl phthalate (DOP) loading on morphology and thermal and mechanical properties of the poly(vinyl chloride)/organically modified montmorillonite/DOP (PVC/O-MMT/DOP) nanocomposites are studied in this paper. Results of transmission electron microscope (TEM) indicate that O-MMT is partially intercalated and exfoliated in all PVC/O-MMT/DOP nanocomposites. It shows that the addition of DOP has no obvious influence on the dispersion of O-MMT in the PVC/O-MMT/DOP nanocomposites. Young's modulus and tensile strength of the PVC/O-MMT/DOP nanocomposites are significantly decreased as the amount of DOP is increased. The thermal degradation onset temperature and glass transition temperature (Tg) of the PVC/O-MMT/DOP nanocomposites are decreased as the amount of DOP is increased. On the other hand, the elongation at break of the PVC/O-MMT/DOP nanocomposites is increased as the amount of DOP is increased. Also, the first thermal degradation weight loss (ΔY) of the PVC/O-MMT/DOP nanocomposites is increased as the amount of DOP is increased. While increasing DOP loading, the PVC/O-MMT/DOP nanocomposites change from a rigid product to a semirigid product and finally into a flexible product. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are a class of high-molecular-weight polyesters made from hydroxy fatty acid monomers. PHAs produced by microorganisms have diverse structures, variable physical properties, and good biodegradability. They exhibit similar physical properties to petroleum-based plastics but are much more environmentally friendly. Medium-chain-length polyhydroxyalkanoates (mcl-PHAs), in particular, have attracted much interest because of their low crystallinity, low glass transition temperature, low tensile strength, high elongation at break, and customizable structure. Nevertheless, high production costs have hindered their practical application. The use of genetically modified organisms can reduce production costs by expanding the scope of substrate utilization, improving the conversion efficiency of substrate to product, and increasing the yield of mcl-PHAs. The yield of mcl-PHAs produced by a pure culture of an engineered microorganism was not high enough because of the limitations of the metabolic capacity of a single microorganism. The construction of artificial microbial consortia and the optimization of microbial co-cultivation have been studied. This type of approach avoids the addition of precursor substances and helps synthesize mcl-PHAs more efficiently. In this paper, we reviewed the design and construction principles and optimized control strategies for artificial microbial consortia that produce mcl-PHAs. We described the metabolic advantages of co-cultivating artificial microbial consortia using low-value substrates and discussed future perspectives on the production of mcl-PHAs using artificial microbial consortia. [ABSTRACT FROM AUTHOR]

Isotactic poly(cyclohexene carbonate) (iPCHC) is a newly developed degradable semi-crystalline polymer. In this paper, the crystallization kinetics of iPCHC above the glass transition temperature (Tg) and the enthalpy relaxation kinetics below Tg were studied by using a commercial fast-scan chip-calorimeter—Flash DSC 1. Results showed that half crystallization time of iPCHC as a function of crystallization temperature presented the typical bell shape. And iPCHC showed a maximum crystallization rate at 190 °C, with the half crystallization time 153 s. IPCHC enthalpy relaxation time in 85 °C ~ 100 °C temperature range decreases with isothermal temperature. The above results have great significance to the development of processing and application of novel crystallizable polycarbonate materials. [ABSTRACT FROM AUTHOR]

Nowadays, powder coating can be used for many application, especially for protection against corrosive environments. Powder coating is usually done with using an electrostatic device and spraying gun. With using this method, a thin film layer is created on the surface which can play decorative or protective role. In this paper, the effect of some factors such as size of powder, charging, voltage, air flow, gun distance, charge-to-mass ratio, feed rate, coating functionality, glass transition temperature (Tg), viscosity, catalyst, temperature and curing time on the coating properties and their influence on the coating were mentioned. In recent years, nano composite polymers have been considered severely. Coating properties are improved by adding nanoparticles such as clay, SiO2, TiO2 and Al2O3 to the polymer composition. These coatings are used for reducing the gas permeability, thermal stability, optical clarity and increasing the mechanical and corrosion properties of coatings also these coatings have high mechanical properties that can be pointed to its high abrasion resistance. In this paper, the corrosion properties and the effect of adding nanoparticles on the corrosion resistance properties of powder coatings have been investigated, also the mechanical properties of powder coatings were reviwed. [ABSTRACT FROM AUTHOR]

Blending polylactide (PLA) with poly(d-lactide) (PDLA) and cellulose nanocrystals (CNC)-based stereocomplex (SC) nanohybrids presents practical approach to produce fully biobased blends and nanocomposites with enhanced properties. This paper investigated the nucleation effect of PLA/PDLA and PLA/PDLA-g-MAH/CNC nanohybrids at low loading levels on the non-isothermal crystallization, morphology, as well as thermal and thermo-mechanical properties of PLA-based samples. Neat PLA, blends and nanocomposites were produced by conventional and microcellular injection molding. Nitrogen (N2) in a supercritical state was used as the physical blowing agent for preparation of microcellular samples. CNC-based SC showed superior nucleating efficiency compared to SC nucleating agents. However, low mold temperature resulted in relatively low degree of crystallinity (~ 15%). In addition, decrease in cell size and increase in cell density of microcellular samples have been observed after introduction of both nucleating agents. Slight increase in mechanical properties of nucleated samples compared to neat PLA has been ascribed to the higher degree of crystallinity. Despite these, decrease in all mechanical properties of microcellular samples has been noticed when compared to solid counterparts. Furthermore, dynamic mechanical analysis (DMA) reveals subsequent foaming and dramatic decrease in dimensional stability of microcellular samples above glass transition temperature (Tg). The storage modulus in a glassy region has been improved in both solid blends and nanocomposites. In addition, shift of Tg due to restricted chain mobility of PLA due to retarded relaxation of amorphous regions due to SC interactions has been observed. [ABSTRACT FROM AUTHOR]

This paper describes the common structure of the longitudinal composite leaf spring as well as the stress of different parts. Combined with force analysis, various failure modes may occur in the middle and end parts of the composite leaf spring. Attention should be paid to the stress concentration in the clamping area in the middle of the leaf spring, caused by U-bolt pre-tightening. At the end of the composite leaf spring, enough bolt hole-edge distances shall be ensured and attention should also be paid to the stress concentration caused by the bolt. In spring design, the static stiffness of the composite leaf spring can be appropriately increased to ensure the suspension has sufficient offset frequency. At the same time, attention should be paid to the glass transition temperature (Tg point) value of the resin, which is suggested to be higher than 80 °C. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses are attracting interest nowadays due to their various technological applications like telecommunications, computer memories, chemical, and ionic sensors, writing channel waveguides and photo-detectors. These glasses possess large transmission in middle, far and near spectral region. Se–Te alloys have created extreme interest due to their greater hardness, lower aging effect, higher photosensitivity, and higher crystallization temperature as compared with amorphous Se. A review of fabrication, optical properties, characterization techniques, doping effect of various elements on Se–Te compounds and also their optoelectronic applications are discussed in the present paper which can help the researchers to expedite their research work in the field of chalcogenide glasses. [ABSTRACT FROM AUTHOR]

In this paper, applying the density scaling idea to an associated liquid 4-methyl-2-pentanol used as an example, we identify different pressure-volume-temperature ranges within which molecular dynamics is dominated by either complex H-bonded networks most probably leading to supramolecular structures or non-specific intermolecular interactions like van der Waals forces. In this way, we show that the density scaling law for molecular dynamics near the glass transition provides a sensitive tool to detect thermodynamic regions characterized by intermolecular interactions of different type and complexity for a given material in the wide pressure-volume-temperature domain even if its typical form with constant scaling exponent is not obeyed. Moreover, we quantify the observed decoupling between dielectric and mechanical relaxations of the material in the density scaling regime. The suggested methods of analyses and their interpretations open new prospects for formulating models based on proper effective intermolecular potentials describing physicochemical phenomena near the glass transition. [ABSTRACT FROM AUTHOR]

Copolymerized poly(m-phenylene isophthalamide) (co-PMIA) was synthesized by solution polycondensation using m-phenylenediamine and isophthaloyl dichloride and 3,4′-oxydianiline (3,4′-ODA). This paper described the preparation and characterization of the copolymers from various contents 3,4′-ODA to afford co-PMIA with ideal high molecular mass. The copolymer showed excellent thermal stability with the glass transition temperature of 267 °C and the onset decomposition temperature (5% mass loss) of 445 °C. The thermal degradation of co-PMIA was measured with various thermal analytical techniques; the pyrolysis products were obtained and analyzed under air atmosphere. The possible thermal decomposition mechanism of co-PMIA was discussed. The present pyrolysis was investigated using TG under air atmosphere at four different heating rates (5–20 °C min−1). Three different kinetic methods, the iso-conversional Ozawa–Flynn–Wall and Kissinger and Crane methods were applied on TG data of co-PMIA to calculate the kinetic parameters including activation energy, pre-exponential factor and reaction order. [ABSTRACT FROM AUTHOR]

Corroded subsea pipe repaired with composite material is more and more used because of its low cost, simple process and short time, but the repair effect will be affected by factors such as temperature and material degradation. To study the law of the effect, the finite element method is used to analyze ultimate loads on repaired pipe by considering the factors of temperature and material degradation. The results show that the ultimate yielding and bursting pressure decreases with the increase in temperature for both the defect pipe and repaired pipe under temperature and internal pressure. The ultimate pressures are larger when both ends of the pipe are fixed comparing with one end is free, but they also decrease faster as the temperature increases. Experiments show that elastic modulus and glass transition temperature of composite will decrease when exposed to prolonged seawater and high temperature. The degradation of composite repair layer performance has a great effect on the ultimate pressure of pipe, and the failure of the repair area will be caused under long-time harsh environment. In this paper, the design repair thickness of composite is obtained, which could improve the repair efficiency of corroded pipes and reduce cost as well. [ABSTRACT FROM AUTHOR]

This paper presents the thermal studies of organic–inorganic [Poly Pyrrole (PPy)–Lanthanum calcium manganite (LCM)] nano composites synthesized via facile in situ chemical oxidation and sol gel methods respectively. The morphology and crystal structure were analysed through scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) techniques respectively. The ac electrical conductivity, transport properties like dielectric constant, dielectric loss, real and imaginary part of electric modulus of pure PPy and PPy/LCM nano composites were analyzed in the temperature range 30 °C to 180 °C and in the frequency range from 100 Hz–5 MHz. Thermal stability of pure PPy and PPy/LCM nano composites were analyzed in the temperature range 30 °C to 800 °C by Thermogravimetric analysis (TGA) and Differential thermal analysis. The contributor for thermal degradation were analysed by fourier transmission infra red studies. DC conductivity study was carried out in the temperature range 30 °C to 180 °C. The activation energy was calculated using arrhenius plots. SEM and TEM images show spherical structure for pure PPy, agglomeration for pure LCM and PPy/LCM nano composites show spherical with LCM embedded in the PPy chain. The XRD analysis for pure PPy, LCM and PPy/LCM nano composites show amorphous, orthorhombic and semicrystalline structures respectively. AC electrical conductivity of the samples tend to merge at high frequency side. Dielectric constant show frequency dependence at all temperature. Real and complex electric modulus analysis show contribution of grain and grain boundary for the ac electrical conductivity. DC conductivity shows ionic conduction. The AC and DC conductivities were found to be high for PPy/LCM30 weight percent and PPy/LCM40 weight percent nano composites respectively. The activation energy of PPy/LCM40 was found to be high. TGA shows that the glass transition temperature of pure PPy is not much affected with the incorporation of LCM nano particle to the PPy chain. [ABSTRACT FROM AUTHOR]

The present paper describes the novel aliphatic polyamide 6 (PA6) copolyamides by the melt polymerization reaction of our newly synthesized aliphatic diamine monomer: N1,N6-Bis-(2-aminoethyl)adipamide (BAEA). The BAEA/CHDA (1,4-cyclohexanedicarboxylic acid) salt was prepared by pertinent long-chain polyamide with the cycloaliphatic ring and isolated as white solid, utterly characterized for the first time. The chemical structure of BAEA, BAEA/CHDA salt and copolyamides (PA6-BAEA/CHDA) was identified by 1H NMR and FT-IR spectroscopy. Depending on the chemical compositions, the viscosity and molecular weight of the copolyamides were in the range of 19,447–13,536 g mol−1 and 2.74–2.2 dL g−1. With increasing BAEA/CHDA salt molar ratio in the synthesized copolyamides, their melting temperatures (Tm) decreased from 212.7 to 170.4 °C, and the glass transition temperatures (Tg) increased from 60 to 89.4 °C. Besides, the as-synthesized all copolyamides possess nearly similar thermal stability (Td-50% = 439.59 − 443.38 °C) as neat PA6. Mechanical testing data revealed that with an increase in a proportion of BAEA/CHDA salt, Young's modulus of copolyamides is increased from 698.54 to 1093.89 MPa, while the tensile strength is increased by 8.1%. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigation on the development of frits for single fast-firing glazes with variable BaO content based on the SiO2–Al2O3–CaO–MgO–ZnO–(BaO) system, fired at a maximum temperature of 1220 °C. The study of the correlation between the composition, structure and crystallization of frits and glazes was carried out using various methods for materials characterization, including differential scanning calorimetry (DSC), dilatometry (DIL), hot-stage microscopy (HSM), X-ray diffraction and scanning and transmission electron microscopy. DSC and X-ray diffraction showed a high tendency to crystallize the tested frits. DSC curves showed that all glazes crystallized during heating in a narrow-temperature range ≈ 938–955 °C, and the introduction of BaO shifted the maximum of exothermic peaks toward higher temperatures. X-ray analysis revealed the presence of diopside and anorthite as the main crystalline phases. The introduction of 5 mass% BaO to the frit composition promoted the crystallization of the additional crystalline phase of barium feldspar (BaAl2Si2O8). In addition, in this composition a strong exothermic effect on the DSC curve at the cooling stage was observed. The analysis of data obtained from thermal studies also showed that the addition of BaO to the chemical composition of the frits resulted in a decrease in the glass transition temperature (Tg) and in reduction in viscosity calculated on the basis of the Vogel–Fulcher–Tammann equation (HSM, DIL). [ABSTRACT FROM AUTHOR]

UV-curable epoxy acrylate oligomer was synthesized via one-pot and two-step method by the ring-opening reaction of bisphenol-A epoxy resin (DGEBA) with dimer acid (DA) and acrylic acid (AA) in this paper. The molecular chain was firstly extended with DA. Then, AA, as a blocking agent, played the role in introducing unsaturated bonds to the chain. The water-based dispersion of epoxy acrylate was fabricated by subsequent phase-inversion emulsification in the presence of methacryloxypropyl silsesquioxane (MASQ). Compared with the traditional UV-curable epoxy acrylate, emulsions contain much less volatile organic compounds (VOC), which are more widely used in the coating industry. Because of the introduction of unsaturated bonds, MASQ participated in free-radical polymerization when incurred by UV, resulting in a better compatibility with epoxy acrylate. The cured samples were characterized with dynamic thermomechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and contact angle measurement (CA). The results indicated that the thermal property, flexibility, and water resistance all improved with the increasing proportion of DA, which may contribute to the long hydrophobic chain. Besides, the organic-inorganic and cage-like structure of MASQ also contributed to the enhancement of thermal property, water resistance, glass transition temperature, and storage modulus. With the above favorable properties and performances, the dimer fatty acid epoxy-acrylate resins will demonstrate promising applications in waterborne coatings. [ABSTRACT FROM AUTHOR]

In the area of pressure-sensitive adhesives (PSAs), acrylic PSAs have been successfully applied in many fields, including self-adhesive tapes, sign labels, carrier-free tapes, double-sided tapes and protective films, but applications of heat-resistant acrylic PSAs are relatively rare. In this study, the thermal stability of acrylic polymer containing maleimide (Mal) functional groups has been investigated. The PSAs were synthesized by acrylic monomers and Mal through copolymerization. The influence of Mal on the viscosity, molecular weight (Mw, Mn), glass transition temperature, thermogravimetric analysis and contact angle of acrylic PSAs was also studied. The adhesion performance and thermal stability of acrylic PSAs could be significantly enhanced by increase in Mal content of the synthesized resin. After 3 h of treatment in drying oven at 170 °C, the modified PSAs can be peeled (180°) off from the substrate without residues on substrate surface at room temperature, while the non-modified acrylic PSAs possessed residues after treatment from 110 °C. The maximum 180° peel strength of modified PSA films was 12.7 N/25 mm when the content of Mal was 7.5 wt%. [ABSTRACT FROM AUTHOR]

The importance of oil–water separator has increased due to environmental pollution caused by marine accidents. Many studies related to fabrication method of superhydrophobic surface have been conducted because those functional surfaces are an important component used in oil and water separators. However, processes that can be applied to large area and mass production still exist as limitations. In this paper, superhydrophobic surfaces were fabricated on polytetrafluoroethylene (PTFE) surface by hot imprinting. To impart rough surface morphology to PTFE surface, hot imprinting process using an electrical discharge textured (EDT) mold was conducted. It was found that undercut of a discharge crater on the EDT surface induced tensile deformation of PTFE surface during the hot imprinting process resulting in microfibril development. As a result, PTFE surface had rough morphology consisting of replicated EDT surface and microfibril network. Imprinted PTFE sheets showed high water contact angles about 154.3° with low contact angle hysteresis about 1.4°. Additionally, the effects of process temperature and roughness of the EDT mold on microfibril formation were investigated. It was found that microfibril formation is activated when the process temperature reaches glass transition temperature (115 °C) of PTFE. The PTFE sheets for oil–water separation were prepared by hot imprinting and followed by additional drilling process. The optimal hole diameter with respect to efficiency of oil–water separation was determined through experiments and separation of oil and water was effectively conducted. [ABSTRACT FROM AUTHOR]