Glass Melting Research Articles

Effects of cerium oxide and cerium sulfate on the optical behavior of synthesized garnet glass ceramics

In this study, the YAG silicate glasses containing the cerium sulfate and cerium oxide salts (17YO3-33Al2O3-40SiO2-2AlF3-3NaF-2CeO2-3B2O3), separately were produced by melting method and glass ceramics were produced by heat treatment of base glasses. According to Photo Luminescence spectrums of both glasses there were emissions in the range of 466 and 435 nm wavelengths related to cerium ions. It was shown that by heating treatment, garnet crystal (in sulfated sample) formed less than the sample with cerium oxide. The emission spectra of both glass-ceramics, when excited at 240 nm, fall within the wavelength range of 460 nm. Also, the 534 and 660 nm emissions wavelengths were obtained by 340 nm wavelength excitation. Heat treatments were done by oxide atmosphere in tubular furnace (single step), SPS sintered powder and in hydrogen atmosphere (by two steps heating). According to XRD results the 24 hrs. heat treating time and the 1060 °C temperature affect the entry of cerium into the garnet structure. Finally, by comparing the spectroscopic results the optical response of the garnet glass-ceramic synthesized in the hydrogen atmosphere was obtained at 400 nm wavelength that indicated this garnet can be applied in the LED industry.

Thermal Stability of ZnO/Tm<sub>2</sub>O<sub>3</sub> Substitution on Tellurite-Zinc-Bismuth-Sodium (TZBN) Glasses

Tm2O3 doped tellurite-zinc-bismuth-sodium (TZBN) glass samples with varying compositions were prepared through melt quenching technique. The composition of these glass was 60 TeO2 - (30-x) ZnO - 5 Bi2O3 - 5 Na2O - x Tm2O3 with (x = 0.5; 1.0; 1.5; 2.0 and 2.5 mol%). We reported the result of a systematic study of the thermal properties of these glass by using differential thermal analysis (DTA). The thermal characteristics of these glass (glass transition, Tg, crystallization, Tc, and melting, Tm) increased significantly with Tm2O3 content and the glasses were more thermally stable (greater ΔT=Tc-Tg). The glass transition value slightly increased from 314 to 323 °C otherwise thermal stability ΔT changed from 112 to 131°C. The ratio of Tg/Tm values for TZBN doped Thulium glasses were about 0.558 to 0.589, indicated that these glasses possess good thermal stability. The Hruby parameter (Kg) with Tm3+ doped in this study improved glass-forming ability, which is desirable for various applications such as optical fibers drawing and sensors.

Preparation of ZIF-62 polycrystalline and glass membranes for helium separation

Defects among the grains of MOF polycrystalline membranes lead to non-selective gas transport, thereby reducing their selectivity in gas separation. In this work, ZIF-62 polycrystalline membranes with a well-intergrown structure were prepared on MXene-modified supports. Subsequent thermal treatment transformed the membranes into glass membranes, effectively eliminating non-selective defects at grain boundaries. Due to the incorporation of the MXene film and the vertical positioning of the support during the solvothermal process, only a minimal portion of the glass melt infiltrated into the porous support. Across the temperature range of 303 K–423 K and pressure range of 1 bar–3 bar, the ZIF-62 glass membranes showcased superior helium separation property and long-term chemical stability (resistant to CO2 and H2O). The helium permeance reached approximately 51 GPU, with selectivities against N2 and CH4 being 17.4 and 13.9, respectively, outperforming current MOF membranes.

Expanding the shelf life of chicken fillets by the use of polylactic acid (PLA) active films: An investigation of orange oil antibacterial potential

AbstractIn this study, orange oil was incorporated into biodegradable polylactic acid (PLA) at various concentrations (1.25%, 1.875%, 2.5%, and 3.75% w/v) to develop potential antimicrobial food packages. Increasing orange oil concentration caused a gradual increase in the films' opacity values, making them more appropriate for packaging of foods having a potential to be affected from UV‐light. Independent of orange oil concentration, the water vapor permeability of the films decreased. While orange oil incorporation did not alter thermal stability of the active films, a slight reduction in glass transition and melting temperature values was observed. The antimicrobial activity of the films was examined on the most common food‐borne pathogens (E. coli, S. aureus), and it is only the film containing 3.75% w/v (PLA_3) that showed an inhibitory activity on both microorganisms. Finally, the shelf life of the chicken fillets packed with neat PLA (PLA_0) and PLA_3 films was compared, and PLA_3 increased the shelf life up to day‐9.Highlights Various concentrations of orange oil were used to develop active polylactic acid (PLA) films. Opacity of the films increased with increasing oil concentration. Incorporation of orange oil resulted in decreasing water vapor permeability. Orange oil worsened both tensile strength and elongation at break of films. PLA_3 inhibited the growth of microorganisms and extended the shelf life of chicken fillet.

Aging processes in dental thermoplastics – Thermoanalytical investigations and effects on Vickers as well as Martens hardness

ObjectiveThe influence of various aging protocols, representing and accelerating influences present in the dental context, on possible changes in the microstructure and mechanical properties of thermoplastics was investigated. In order to minimize the complexity of the systems, first pure polymers and then later the equivalent dental polymeric materials were analyzed. Materials and methodsPure polymers (Poly(methyl methacrylate) – PMMA, Polyoxymethylene homopolymer – POM-H, Polyether ether ketone – PEEK, Nylon 12 – PA12, Polypropylene – PP) were analyzed before as well as after applying different aging protocols relevant to the oral environment (ethanol, thermocycling, alkaline and acidic setting) by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermoanalytical parameters used were glass transition temperature (Tg), melting peak and crystallization peak temperature (Tpm, Tpc) and decomposition behavior.In a second step selected commercially available dental products (Telio CAD – PMMAD, Zirlux Acetal – POMD, Juvora Natural Dental Disc – PEEKD) aged by the protocol that previously showed strong effects were examined and additionally tested for changes in their Vickers and Martens hardness by Mann-Whitney-U test. ResultsThe combinations of pure polymers and viable aging protocols analyzed within this study were identified via TGA or DSC as PA12 & thermocycling, POM-H & denture cleanser/lactic acid/ethanol, PP & lactic acid. The dental polymeric materials PMMAD and POMD due to aging in lactic acid showed slight but significantly (p < 0.01) reduced Vickers and partly Martens hardness. PEEK showed the greatest material resistance within this study.

Development of Sustainable and Active Food Packaging Materials Composed by Chitosan, Polyvinyl Alcohol and Quercetin Functionalized Layered Clay.

In order to solve the problems of insufficient active functions (antibacterial and antioxidant activities) and the poor degradability of traditional plastic packaging materials, biodegradable chitosan (CS)/polyvinyl alcohol (PVA) nanocomposite active films reinforced with natural plant polyphenol-quercetin functionalized layered clay nanosheets (QUE-LDHs) were prepared by a solution casting method. In this study, QUE-LDHs realizes a combination of the active functions of QUE and the enhancement effect of LDHs nanosheets through the deposition and complexation of QUE and copper ions on the LDHs. Infrared and thermal analysis results revealed that there was a strong interface interaction between QUE-LDHs and CS/PVA matrix, resulting in the limited movement of PVA molecules and the increase in glass transition temperature and melting temperature. With the addition of QUE-LDHs, the active films showed excellent UV barrier, antibacterial, antioxidant properties and tensile strength, and still had certain transparency in the range of visible light. As QUE-LDHs content was 3 wt%, the active films exhibited a maximum tensile strength of 58.9 MPa, representing a significant increase of 40.9% compared with CS/PVA matrix. Notably, the UV barrier (280 nm), antibacterial (E. coli) and antioxidant activities (DPPH method) of the active films achieved 100.0%, 95.5% and 58.9%, respectively. Therefore, CS/PVA matrix reinforced with QUE-LDHs has good potential to act as an environmentally and friendly active packaging film or coating.

Current trends in medium‐chain‐length polyhydroxyalkanoates: Microbial production, purification, and characterization

AbstractPolyhydroxyalkanoates (PHAs) have gained interest recently due to their biodegradability and versatility. In particular, the chemical compositions of medium‐chain‐length (mcl)‐PHAs are highly diverse, comprising different monomers containing 6–14 carbon atoms. This review summarizes different feedstocks and fermentation strategies to enhance mcl‐PHA production and briefly discusses the downstream processing. This review also provides comprehensive details on analytical tools for determining the composition and properties of mcl‐PHA. Moreover, this study provides novel information by statistically analyzing the data collected from several reports on mcl‐PHA to determine the optimal fermentation parameters (specific growth rate, PHA productivity, and PHA yield from various structurally related and unrelated substrates), mcl‐PHA composition, molecular weight (MW), and thermal and mechanical properties, in addition to other relevant statistical values. The analysis revealed that the median PHA productivity observed in the fed‐batch feeding strategy was 0.4 g L−1 h−1, which is eight times higher than that obtained from batch feeding (0.05 g L−1 h−1). Furthermore, 3‐hydroxyoctanoate and ‐decanoate were the primary monomers incorporated into mcl‐PHA. The investigation also determined the median glass transition temperature (−43°C) and melting temperature (47°C), which indicated that mcl‐PHA is a flexible amorphous polymer at room temperature with a median MW of 104 kDa. However, information on the monomer composition or heterogeneity and the associated physical and mechanical data of mcl‐PHAs is inadequate. Based on their mechanical values, the mcl‐PHAs can be classified as semi‐crystalline polymers (median crystallinity 23%) with rubber‐like properties and a median elongation at break of 385%. However, due to the limited mechanical data available for mcl‐PHAs with known monomer composition, identifying suitable processing tools and applications to develop mcl‐PHAs further is challenging.

FORMING AND PROPERTIES OF GLASSES MADE FROM TWO THAI BOTTOM ASHES

Industrial wastes are often an under-utilized source of raw materials. Bottom ashes resulting from incineration processes can contain various metal oxides, including many commonly used in glass making. This research studied the forming and properties of glasses made from two bottom ashes. Lignite bottom ash (BL) from Lampang, Thailand and a municipal solid waste incinerator bottom ash (BP) from Phuket, Thailand. Both bottom ashes were found to contain significant amounts of SiO2, CaO, Al2O3, and Fe2O3. After ball milling, the ashes were melted without additions, at temperatures from 1300 to 1500°C. The resulting glasses, as confirmed by XRD, were black and fully opaque, a result of the high Fe2O3 content. It was found that the BP glasses were slightly more refractory, had a greater average thermal conductivity of 1.52 W/m·K and a lower coefficient of thermal expansion (CTE) of 6.97x10-6/°C, compared to the BP glasses, which had an average thermal conductivity of 1.39 W/m·K and a CTE of 7.98x10-6/°C. The BL glasses also had a higher average density of 2.88 g/cm3 and a Vickers hardness of 6.29 GPa, compared to the BP glasses, with average values of 2.74 g/cm3 and 6.06 GPa, respectively. The increase of glass melting temperature up to 1450°C tended to improve the observed properties, followed by a decrease at 1500°C. Despite the atypical glass chemistry of the two bottom ashes, they were successfully melted to produce glasses and the measured properties demonstrated suitable potential to warrant further study.

Star-shaped hosts based on phenyls substituted carbazole: Effects of trifluoromethyl and tert-butyl moieties

To investigate the effects of trifluoromethyl and tert-butyl moieties on the general optoelectronic properties of star-shaped hosts based on phenyls substituted carbazole, we used 3,6,9-tris (4-(tert-butyl)-phenyl)-9H-carbazole (M1) as a reference, and different numbers of electron-withdrawing 3,5-bis(trifluoromethyl) benzene were introduced into 3, 6 and 9 positions of carbazole to obtain compounds 9-(3,5-bis(trifluoromethyl)phenyl)-3,6-bis(4-(tert-butyl)phenyl)-9H-carbazole (M3), 3,6-bis(3,5-bis(trifluoromethyl)phenyl)-9-(4-(tert-butyl)phenyl)-9H-carbazole (M5) and 3,6,9-tris(3,5-bis(trifluoromethyl)phenyl)-9H-carbazole (M6). After the introduction of 3,5-bis (trifluoromethyl) benzene, the thermal temperature at 5 % mass loss of M3, M5 and M6 decreased to 344 °C, while the glass transition temperature and melting point of M3 and M5 showed a significant increase. However, M6 did not show obvious glass transition, but its melting point also showed a significant increase. M3 crystallized at 125 °C as evidenced by differential scanning calorimetry, and the linking model of M3 is helpful to crystalize. In addition, when compared with those of M1, the fluorescence emission peaks of M3 and M6 showed a blue-shift, while M5 showed a red-shift, all of which were in the deep blue emission range. The color purity of blue light for M1 in tetrahydrofuran solution is the highest, and M1 exhibit aggregation-induced emission characteristics. Compared to the photoluminescence quantum efficiency (PLQY) of compound M1 of 39 % in toluene, the PLQYs of M3 and M6 decreased to 34 % and 29 %, and the PLQY of M5 increased to 46 %. The function of the lowest unoccupied molecular orbital trap of M3 film under the external electrical field will increase, which not only offsets the increasing effect of the electrical field to the electron carrier and further decreases the carrier mobility when the electrical field increase, and the same situation is also feasible for the highest occupied molecular orbital traps in M5, M6 and M1. The organic blue light emitting diodes were prepared by using M1, M3, M5 and M6 as the hosts of bis [2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium, and the optimized device of M1 as the host showed the best performance with a maximum luminescence brightness of 2978 cd/m2, maximum current efficiency of 39.42 cd/A and maximum external quantum efficiency of 18.36 %.

A natural butter glyceride as a plasticizer for improving thermal, mechanical, and biodegradable properties of poly(lactide acid)

Polylactic acid (PLA) is a biobased and biodegradable thermoplastic polyester with great potential to replace petroleum-based plastics. However, its poor toughness and slow biodegradation rate affect broad applications of PLA in many areas. In this study, a glycerol triester existing in natural butter, glycerol tributyrate, was creatively explored and compared with previously investigated triacetin and tributyl citrate, as potential plasticizers of PLA for achieving improved mechanical and biodegradation performances. The compatibilities of these agents with PLA were assessed quantitively via the Hansen solubility parameter (HSP) and measured by using different testing methods. The incorporation of these compounds with varied contents ranging from 1 to 30 % in PLA altered thermal, mechanical, and biodegradation properties consistently, and the relationship and impacts of chemical structures and properties of these agents were systematically investigated. The results demonstrated that glycerol tributyrate is a novel excellent plasticizer for PLA and the addition of this triester not only effectively reduced the glass transition, cold crystallization, and melting temperatures and Young's modulus, but also led to a significant improvement in the enzymatic degradation rate of the plasticized PLA. This study paves a way for the development of sustainable and eco-friendly food grade plasticized PLA products.

Development of 3D Printing Filaments from Recycled PLA Reinforced with Nanoclay

This study focused on the development of 3D printing filaments suitable for fused deposition modeling (FDM) by recycling expired polylactic acid (PLA) filaments. The 3D printing filaments were processed into pellets by incorporating montmorillonite (MMT) nanoclay into the expired PLA filaments through twin-screw extrusion with varying concentrations of 1%, 3%, and 5 wt.%. These composite pellets were reprocessed to filaments through a filament extruder with a diameter of 1.75 mm. These filaments underwent different characterization techniques to test its mechanical and thermal properties. The thermal properties showed increasing values in the glass transition temperature, crystallization temperature, and melting temperature with a decrease in the specific heat upon incorporating increasing amount of MMT nanoclay. Furthermore, thermogravimetric analysis (TGA) showed a positive impact with better thermal stability when the MMT content was incorporated. In terms of mechanical properties, the study showed that the addition of 1 wt% MMT nanoclay, provided an increase in both the tensile strength and elastic modulus comparable to the virgin 3D printing PLA filament.

High-temperature and thermal radiation affecting human thermal comfort and physiological responses: An experimental study

Hot environments with high temperatures and thermal radiation are to be found in heat treating, glass melting workshops, etc., which impacts worker thermal comfort and physiological responses. The motivation of this study was to explore the changes of thermal comfort in a high-temperature and thermal radiation environment. Four experimental cases were designed to simulate high temperatures and thermal radiation. Physiological parameters such as skin temperature, ear cancel temperature, heart rate, and weight loss were investigated. Evaporative heat losses and skin wettedness were calculated by Gagge's two node model or weight loss. The results showed that local and mean skin temperatures increased by approximately 4 °C during the exposure. Thermal sensation vote was positively correlated with WBGT. The dynamic relationship between human heat gain, evaporative heat loss and potential thermal risk was framed as Stage A, Stage B, and possibly Stage C. This study could provide the basic information and theoretical evidence for the thermal comfort and thermal risk in high-temperatures and thermal radiation environment.

ŞEKER ŞURUBUYLA TAĞŞİŞ EDİLEN PEKMEZ ÖRNEKLERİNİN TERMAL ÖZELLİKLERİ İÇİN GELİŞTİRİLMİŞ BİR DIFFERENTIAL SCANNING CALORIMETRY ÇALIŞMA

This research was carried out to determine the pH, titratable acidity, ash, specific gravity, color (L*, a*, b*), water activity, electrical conductivity, glass transition temperature (Tg) and melting characteristics of grape and mulberry pekmez samples adulterated with different levels (10%, 30%, 50%) of high fructose corn syrup (HFCS). Ash, titratable acidity and electrical conductivity values have decreased significantly (P&amp;lt;0.05) with the level of adulteration and determined that these properties can be used as a criterion in the determination of adulteration. Two glass transition temperatures occurring between -25.64℃ to -32.58℃ (Tg1) and 23.29℃ to 31.22℃ (Tg2) were detected in all pekmez samples. The single glass transition temperature was determined in the pekmez samples diluted with water, and both the glass transition temperatures and the onset, peak, end temperatures and enthalpy values of the melting peaks increased significantly with the increase in the amount of adulteration (P&amp;lt;0.05).

Elucidating intermolecular forces to improve compatibility of kraft lignin in poly(lactic acid).

Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young's modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.

The influence of the Cr2O3–Mn2O3 colorants system on the spectral characteristics of R2O–PbO–SiO2 glasses

AbstractThe focus of this paper centers on an exploration of optical glasses with high transmittance within the infrared spectrum at wavelength of 1 060 nm, while concurrently demonstrating full absorption within the ultraviolet and visible spectral ranges. The paper analyzes the present state of glasses demonstrating necessary transmittance at IR range, considering their inherent strengths and limitations. In this context, an R2O–PbO–SiO2 glass system with Cr2O3–Mn2O3 colorants system emerges as the subject of this research. Research was conducted to comprehensively assess the impact of this colorant system on the glass spectral characteristics, while considering the potentially detrimental influence of FeO.The principles underlying the industrial production of these glasses are systematically elucidated and presented. It was discovered that using gas heating during the cooling phase of glass melting resulted in the disruption of the spectral homogeneity of the glass, ultimately leading to defective product outcomes. Implementing the methodology of gasless temperature reduction (inertial cooling process) before glass pouring has created a favorable environment for producing high‐quality items. Glass samples from the laboratory tests were obtained, and the researched glass was integrated into serial production.

Rapid synthesis of phosphor-glass composites in seconds based on particle self-stabilization

Phosphor-glass composites (PGC) are excellent candidates for highly efficient and stable photonic converters; however, their synthesis generally requires harsh procedures and long time, resulting in additional performance loss and energy consumption. Here we develop a rapid synthetic route to PGC within about 10 seconds, which enables uniform dispersion of Y3Al5O12:Ce3+ (YAG:Ce) phosphor particles through a particle self-stabilization model in molten tellurite glass. Thanks for good wettability between YAG:Ce micro-particles and tellurite glass melt, it creates an energy barrier of 6.94 × 105 zJ to prevent atomic-scale contact and sintering of particles in the melt. This in turn allows the generation of YAG:Ce-based PGC as attractive emitters with high quantum efficiency (98.4%) and absorption coefficient (86.8%) that can produce bright white light with luminous flux of 1227 lm and luminous efficiency of 276 lm W−1 under blue laser driving. This work shows a generalizable synthetic strategy for the development of functional glass composites.

Study of properties of guar gum and its use in development of packaging film

Discarded plastic materials are now a potential problem throughout the globe; therefore, researchers today attach huge importance and applicability to green chemistry and the sustainable development of biopolymer-based materials that can fulfil the needs of synthetic plastics and polymers and save the biological community of the globe. In this work, a new packaging film was developed by using polyvinyl alcohol (PVA) and guar gum (GG) modified with n-octenyl succinic anhydride (OSA). The objective of the work is to develop a water-resistant film for food packaging applications. In synthesizing the biomaterial film, PVA, glycerol, and guar gum with OSA are used to enhance the capability of water resistance, and the major aim of this study is to improve the hydrophobic nature of guar gum through modification with OSA. The glass transition temperature (Tg = 114.45 °C), crystallization temperature (Tc = 176.85 °C), and melting temperature (Tm = 191.28 °C) of the films indicated better thermal stability. In the characterization study, it was found that 30 % GG/PVA with 5 % OSA provides a better result.

Theoretical study of kinetic arrest, shear elastic modulus, and yielding in simple biphasic colloidal mixtures.

Based on integrating microscopic statistical mechanical theories for structure and ideal kinetic arrest at the naive mode coupling level, we study dynamic localization, the linear elastic shear modulus, applied stress induced modulus softening, and the absolute yielding of simple biphasic binary mixtures composed of equal diameter hard and attractive spheres. The kinetic arrest map is a rich function of total packing fraction, strength of attraction, and mixture composition. The gel to attractive ideal glass transition, the degree of glass melting re-entrancy, and the crossover boundary separating repulsive glasses from attractive glasses vary with the mixture composition. Exponential and/or apparent (high) power law dependences of the elastic shear modulus on the total packing fraction are predicted with effective exponents or exponential prefactors that are sensitive to mixture composition and location in the kinetic arrest map. An analysis of the effective mean square force on a tagged particle that induces dynamic localization reveals a compensation effect between structural correlations and degree of particle localization, resulting in the emergence of a weaker dependence of the shear modulus on mixture composition at very high attraction strengths. Based on a microrheologically inspired formulation of how external stress weakens particle localization and the shear modulus, we analyze mechanical-induced modulus softening and absolute yielding, defined as a discontinuous solid-to-fluid stress-induced transition that can occur in either one or two steps. Estimates of the corresponding yield strains predict that the binary mixture becomes more brittle with increasing sticky particle composition and/or attraction strength.

Structural and thermoanalytical characterization of self-healing polymer: the effect of cross-linking density

The effect of the gradually formed cross-linked structure on the thermal properties and swelling behaviour of modified poly(vinyl alcohol) was investigated. To this aim, the semi-crystalline polymer was functionalized with aldehyde and amino moieties to produce polymers with dynamic imine cross-links, and, thus, with self-healing or curing ability. With increasing degree of functionalization (0.89–7.12%), denser polymer networks cross-linked by dynamic imine bonds were formed, the samples systematically developed thermoset-like properties compared to the pristine, initially thermoplastic PVA. As a result, the introduction of new moieties into the initial PVA lowered the glass transition (from 65.3 to 35.0 °C) and melting temperatures (from 194 to 161 °C), however, a new peak (Tcrd) with growing enthalpy values appeared on the DSC curves, which indicates that more and more energy must be supplied in order to break the imine cross-links formed between the introduced aldehyde and amino groups. The significant impact of the degree of functionalization and cross-linking density on the polymer structure was also clearly demonstrated: the crystallinity decreased as the abundance of the introduced moieties increased and the formation of cross-links proceeded. At the same time, the water desorption enthalpies of the samples increased, suggesting a stronger, chemically cross-linked thermoset-like polymer network compared to the thermoplastic poly(vinyl alcohol).Graphical abstract

Characterization of Interlaminar Friction during the Forming Processes of High-Performance Thermoplastic Composites

Friction is a pivotal factor influencing wrinkle formation in composite material shaping processes, particularly in novel thermoplastic composites like polyetheretherketone (PEEK) and low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fibers. The aerospace sector lacks comprehensive data on the behavior of these materials under forming conditions, motivating this study’s objective to characterize the interlaminar friction of such high-performance thermoplastic composites across diverse temperatures and forming parameters. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to analyze the thermomechanical behaviors of PEEK and LM-PAEK. These data guided friction tests covering room-to-forming temperatures. Horizontal pull-out fixed-plies tests were conducted to determine the friction coefficient and shear stress dependency concerning temperature, pressure, and pulling rate. Below the melting point, both materials adhered to Coulomb’s law for friction behavior. However, above the melting temperature, PEEK’s friction decreased while LM-PAEK’s friction increased with rising temperatures. These findings highlight the distinct responses of these materials to temperature variations, pulling rates, and pressures, emphasizing the need for further research on friction characterization around glass transition and melting temperatures to enhance our understanding of this phenomenon.