Thermal Aging Properties Research Articles

Effect of benzoyl chloride treatment on morphological, thermal, mechanical, and hydrothermal aging properties of date palm/polyvinyl chloride (PVC) composites

The use of natural fibers has seen a significant rise in the composites sector, resulting in the creation of polymer composites with exceptional strength. These environmentally-friendly alternatives offer a compelling substitute for synthetic composites. This study explores the use of date palm waste as reinforcement for the fabrication of polyvinyl chloride (PVC) composites. A surface modification method was essential for improving the binding interaction between palm fibers and PVC composites. The two-hour benzoyl chloride treatment at 140 °C played a crucial role. The study examined the effects of hydrothermal aging on mechanical properties of composites, using various techniques such as surface morphology analysis, Fourier Transform Infrared spectroscopy, and Thermogravimetric Analysis, on composites made of untreated fibers and those treated with benzoyl chloride. Although the treatment of palm fiber-reinforced composites with benzoyl chloride improved their mechanical properties, it is crucial to note that hydrothermal aging reduced their tensile strength by 10%. Despite this, these composites prove to be well-suited for applications requiring moderate strength and stiffness in mild environmental conditions. These composites, while utilizing benzoyl chloride for surface treatment, still represent a more sustainable alternative to traditional synthetic composites by incorporating renewable date palm waste and enhancing mechanical properties, which potentially reduces overall environmental impact.

Natural Rubber/Styrene-Butadiene Rubber Blend Composites Potentially Applied in Damping Bearings.

Natural rubber (NR) composites have been widely applied in damping products to reduce harmful vibrations, while rubber with only a single composition barely meets performance requirements. In this study, rubber blend composites including various ratios of NR and styrene butadiene rubber (SBR) were prepared via the conventional mechanical blending method. The effects of the rubber components on the compression set, compression fatigue temperature rising and the thermal oxidative aging properties of the NR/SBR blend composites were investigated. Meanwhile, the dynamic mechanical thermal analyzer and rubber processing analyzer were used to characterize the dynamic viscoelasticity of the NR/SBR blend composites. It was shown that, with the increase in the SBR ratio, the vulcanization rate of the composites increased significantly, while the compression fatigue temperature rising of the composites decreased gradually from 47 °C (0% SBR ratio) to 31 °C (50% SBR ratio). The compression set of the composites remained at ~33% when the SBR ratio was no more than 20%, and increased gradually when the SBR ratio was more than 20%.

Evaluating Effectiveness of Multi-Component Waste Plastic Bags on Bitumen Properties: Physical, Rheological, and Aging.

This study examines the applicability of an unknown composition waste plastic bag sample as bitumen modifier. The waste components were initially characterized to identify the type of plastics and the level of impurity. Asphalt binder performance was examined for rutting, thermal, and age resistance. The results revealed that the waste plastic bags, predominantly consisted of Low-Density Polyethylene (LDPE) and Linear Low-Density Polyethylene (LLDPE) and contained 6.1% impurities. The binder tests indicated that the waste plastic bags enhanced the rutting resistance of bitumen by one grade, with its modification more similar to LLDPE, rather than LDPE. The thermal degradation and aging properties of the modified binders demonstrated that the bitumen modified by the waste plastic bags exhibited slightly lower resistance to temperature and aging compared to virgin LDPE and LLDPE. This was attributed to the impurities contained in the waste plastic. In conclusion, the analyzed waste plastic bags proved to be suitable for use in binder modification, presenting a viable alternative to virgin LLDPE.

Effect of Silicone Rubber on the Properties of Epoxy/Recovered Carbon Black (rCB) Conductive Materials

The primary focus of this study is to investigate the effect of silicone rubber (SR) content on the mechanical, thermal, electrical conductivity, and morphological properties of epoxy/recovered carbon black (rCB) conductive material. The conductive material is used to produce the electrostatic discharge (ESD) tray for the electronic packaging industry. This study investigated the effect of silicone rubber content (0, 5, 10, 15, and 20 vol.%) on the properties of epoxy/SR/rCB conductive materials, with the rCB content fixed at 15 vol.% for its optimum electrical conductivity. The silicone rubber acts as a toughening agent for epoxy. Through the fracture toughness result, it can be identified that silicone rubber plays a role in improving the toughness properties of the epoxy/SR/rCB conductive material. The optimum results for mechanical properties were recorded at 5 vol.% SR. The addition of SR to the epoxy matrix enhances the electrical properties of the epoxy/SR/rCB conductive material. The effect of thermal aging on epoxy/SR/rCB conductive materials was also studied to determine the properties of the conductive material materials at high temperatures for a long period of time. After thermal aging, the mechanical, thermal, electrical conductivity, and morphological properties of the epoxy/SR/rCB conductive material were slightly reduced.

The influence of palm oil-derived plasticizers and lubricants on the rheological and mechanical properties of styrene butadiene rubber

Researchers have recently focused on green processing aids made from plants and vegetables to avoid the high concentration of polycyclic aromatic hydrocarbons (PAHs) from petroleum-based processing oils, which is hazardous to human health. This paper focuses on the effect of lubricants and plasticisers produced from palm oil on the rheological, mechanical and thermal aging properties of styrene-butadiene rubber (SBR). These lubricants and plasticisers are known as glycerol trioleate (GTO), n-butyl stearate (NBS), ethylene bis-steramide (EBS), ethylene bis-oleamide (EBO), pentaerythritol tetrastearate (PETS) and stearyl stearate. The abrasion performance, visual inspection appearance, and cure characteristics of the lubricants and plasticisers on SBR were examined and compared to processing oil-treated distillate aromatic extract (TDAE), paraffin wax, microcrystalline wax, polyethylene (PE) wax, epoxidised soybean oil (ESBO), and stearic acid. It discovered that rubber compounds based on GTO, stearic acid, and EBS exhibited better abrasion resistance and cure properties than rubber compounds based on processing oil. These samples were selected and subjected to mechanical properties, thermal aging effects analysis and comparison with processing oil. Tensile strength shows that SBR with EBS (22.49 MPa) and EBS with GTO (EBS/GTO; 21.25 MPa) are closely similar to SBR compounds with processing oil (21.02 MPa). The findings imply that EBS and EBS/GTO, green plasticisers and lubricants, are viable alternatives to petroleum-based processing oils while being cost-effective for tire production.

Research progress in modified mineral oil, natural ester and mixed oil in transformers

AbstractThree kinds of typical insulating oil including mineral oil (MO), natural ester (NE), and mixed insulating oil used in transformers are reviewed. The basic physicochemical, electrical properties and engineering application of the oil were firstly introduced. Then, the nano‐modified mechanism for MO and NE is explored. The effects of various nanofillers on electrical properties, thermal conductivity and ageing stability of MO and NE are compared. Moreover, the preparation process of mixed insulating oil is described, and the enhancement of electrical performance, thermal ageing properties, and kinematic viscosity of mixed insulating oil are analysed. Finally, the performance parameters of nano‐modified MO, NE and mixed insulating oil are analysed, and the future development trend of insulating oil is also discussed.

Impact of low molecular weight acid and moisture on the thermal ageing properties of palm oil

<span>This study examines the effect of low molecular weight acid (LMA), moisture and oxygen on the thermal ageing characteristics of refined, bleached, and deodorised palm oil (RBDPO). The paper moisture was varied between 0.5% and 3.5%. The oil was initially subjected to 0.2 g of LMA and 20 mbar of oxygen pressure. The thermal ageing experiment was performed at 120 °C and 140 °C for 28 days. Several dielectric and physiochemical parameters were measured which included dielectric dissipation factor, relative permittivity, resistivity, moisture in oil, acidity, and thermogravimetric analysis (TGA). It is found that LMA and moisture in paper do not affect the <span>relative permittivity of RBDPO and mineral oil (MO). The dielectric dissipation factor of RBDPO and MO reveals slight increment trends within the ageing time. The decrements of resistivities occur after 7 days of ageing</span> <span>for both RBDPO and MO while only RBDPO shows decrement trend of moisture in oil. The ageing patterns of relative permittivities, dielectric dissipation factors and resistivities for RBDPO are similar to MO. The</span> <span>increment of acidity for RBDPO is more apparent that MO throughout the ageing time. All RBDPOs are more resistant to ageing than MO based on the TGA.</span></span>

Main-Chain Benzoxazines Containing an Erythritol Acetal Structure: Thermal and Degradation Properties.

In this paper, the bio-based raw material erythritol was used to introduce an acetal structure into the benzoxazine resins. The benzoxazine-based resins containing an erythritol acetal structure could be degraded in an acidic solution and were environmentally friendly thermosetting resins. Compounds and resins were characterized by 1H nuclear magnetic resonance (1H NMR) and Fourier-transform infrared (FT-IR) analyses, and melting points were studied by a differential scanning calorimeter (DSC); the molecular weight was analyzed by gel permeation chromatography (GPC). The dynamic mechanical properties and thermal stability of polybenzoxazine resins were studied by dynamic mechanical thermal analysis (DMTA) and a thermogravimetric analyzer (TGA), respectively. The thermal aging, wet-heat resistance, and degradation properties of polybenzoxazine resins were tested. The results showed that the polybenzoxazine resins synthesized in this paper had good thermal-oxidative aging, and wet-heat resistance and could be completely degraded in an acidic solution (55 °C DMF: water: 1 mol/L hydrochloric acid solution = 5:2:4 (v/v/v)).

Sustainable green composite of yam and agricultural waste corn stalk fiber with good mechanical, thermal, optical, aging performance and excellent biodegradability

Sustainable green composites with safe biodegradability produced using environmentally benign materials are required as modern-day alternatives for harmful synthetic materials. Agricultural waste such as corn stalks and underutilized natural polymer sources such as yam are significant potential candidates in this regard. In our work, a green composite of yam and alkali-treated corn stalk fiber was prepared through a simple solution casting and oven-drying method. The successfully prepared green composites displayed good mechanical and thermal properties as the corn stalk fibers effectively reinforced the yam bioplastic matrix. Spectral studies such as FTIR, SEM, and p-XRD confirmed the probable structural changes and formation of the composites. Prepared green composites possessed high resistance and good thermal (−2 °C and 70 °C), UV (254 nm for 180 hours), and chemical aging properties along with low moisture absorption behavior. Further, the green composites showed excellent biodegradable nature under normal environmental conditions. Thus, potentially capable green composite for applications in packaging, biomedical, automobile, and construction sectors was reported here.

Probing the Effect of Linear and Crosslinked POE-g-GMA on the Properties of Asphalt.

The copolymer ethylene-octene (POE) has good aging resistance and is an inexpensive asphalt additive compared to the styrene-butadiene-styrene copolymer (SBS). However, POE is easy to segregate in asphalt during storage at high temperatures. Grafting glycidyl methacrylate (GMA) onto the molecular backbone of POE (i.e., POE-g-GMA) may solve this problem, for the epoxy groups in GMA can react with the active groups in asphalt. Asphalt modified with linear and crosslinked POE-g-GMA were prepared, and the hot storage stability, physical properties and thermal oxidation aging properties were discussed in detail. The results show that linear and low-degree crosslinked POE-g-GMA-modified asphalts are storage-stable at high temperatures via measurements of the difference in softening points and small-angle X-ray scattering (SAXS) characterizations from macro and micro perspectives. The difference in softening points (ΔSP) between the upper and lower ends is no more than 3.5 °C for modified asphalts after 48 h of being in an oven at 163 °C. More importantly, the crosslinking modification of POE-g-GMA can further increase the softening point and reduce the penetration as well as rheological properties via conventional physical property, dynamic shear rheometer (DSR) and multiple-stress creep recovery (MSCR) tests. Furthermore, asphalt modified with crosslinked POE-g-GMA reveals better aging resistance via measurements of the performance retention rate and electron paramagnetic resonance (EPR) characterizations after a rolling thin film oven test (RTFOT). This work may provide further guidelines for the application of polymers in asphalt.

Study on properties and application of chloroprene rubber/polyurethane modified asphalt sealant

Under the long-term effect of loads and climate conditions, various diseases can appear on the surface of asphalt pavement, causing deterioration in its performance. To address the pavement surface cracks during service, the present study developed a crumb rubber/polyurethane (CR/PU) compound as the modified asphalt sealant with excellent properties. The optimal material proportion, ensuring the best asphalt compatibility was selected to meet the requirements of standard hot-poured sealants for pavement. Additionally, the fineness and content of CR were determined. The research investigated rheological properties, aging performance, microstructure, and modification mechanism of the CR/PU sealant was then applied in an engineering project to evaluate its effectiveness in treating pavement cracks, and suitable construction techniques were summarized. The results revealed that the in-situ polymerization method is an appropriate approach for preparing the CR/PU sealant, demonstrating good high-temperature deformation resistance and low-temperature crack resistance, indicating synergistic interactions between CR and PU. Among various compositions, the sealant with 30 %PU and 15 %CR content exhibited the best thermal oxygen and UV aging properties. Microscopic tests indicated that CR was physically blended with asphalt, while PU underwent chemical modification and formed a cross-linked network structure with asphalt, resulting in CR dispersion around it, enhancing the thermal stability of the system. Furthermore, the test section displayed an ideal crack treatment effect, demonstrating the sealant’s excellent sealing, durability, and watertight capacity.

Effect of Glycerol as Processing Oil in Natural Rubber/Carbon Black Composites: Processing, Mechanical, and Thermal Aging Properties.

The present work aims to study the effect of glycerol as a replacement for mineral oils in natural rubber (NR) composites to obtain suitable properties via cure characteristics, mechanical properties, and thermal stability. Glycerol was used at a 5 phr rate in the compound with carbon black as a reinforcing filler and was compared to mineral processing oils such as aromatic oil, treated distillate aromatic extracted oil, and paraffinic oil. Compared to the other oils, glycerol exhibits better maximum torque and torque differences. Also, a shorter scorch time, cure time, and a higher cure rate index of the compounds were observed. However, although the received mechanical properties, including tensile strength, elongation at break, and compression set of the vulcanized rubber using glycerol showed slightly lower values than the others, the 100% and 300% moduli, as well as the hardness of the composites filled with glycerol, exhibit better values relative to the other commercial oils. These findings demonstrate that glycerol overall presents a good balance of properties, making it beneficial to use glycerol as a substitute for mineral oil in tire, shoe sole, and rubber stopper applications.

Ce doped LaAlO3 pigments with high NIR reflectance and modification of thermal aging properties of polyvinyl chloride

Based on the modified weather resistance of PVC plastics, a series of La1-xCexAlO3 inorganic pigments were synthesized in this study. A single La1-xCexAlO3 (x varies from 0.00 to 0.20) phase replacement solid solution of rhombohedral crystal structure with the addition of more Ce3+ doping. The sample pigments demonstrated a curved rod to spherical particle morphology change as Ce doping amount increased. The analysis by X-ray photoelectron spectroscopy (XPS) demonstrated that the cerium ion chemical valence states in the synthesized samples were + 3 and + 4. The carrier concentration and electron trap theory can be used to understand the variation in near-infrared reflectance of La1-xCexAlO3 pigment powder from 72.55% to 83.35%. Electric charge transfer (La 3d ↔ Ce 3d) can be used to describe how the La1-xCexAlO3 pigment shifts from white to orange to yellow. When PVC plastic is modified with pigment, the near-infrared reflectance varies from 52.87% to 61.63%. Inner surface temperature of La1-xCexAlO3/PVC composite plastics can be lowered by 8.5–13.7 °C, and the weather resistance of the modified PVC plastic is greatly increased. In conclusion, the modification of PVC plastics with La1-xCexAlO3 inorganic pigments can significantly reduce the surface temperature of plastics and prolong their service life.

Effect of silane coupling agent and cellulose nanocrystals loading on the properties of acrylonitrile butadiene rubber/natural rubber nanocomposites

In this study, the effects of cellulose nanocrystal (CNCs) loading and the silane coupling agent (3-triethoxysilylpropyl) tetrasulfide (Si-69) on the properties of a nanocomposite composed of acrylonitrile butadiene rubber (NBR) and natural rubber (NR) at a 50/50 ratio were explored. CNCs were extracted from Luffa cylindrica and incorporated into NBR/NR nanocomposites at a level of 0–5 parts per hundred rubber (phr). Incorporation of CNCs exhibited safe cure and good processability of rubber nanocomposites. The presence of Si-69 in the NBR/NR nanocomposites improved the interaction between CNCs and the polymer matrix, resulting in improved mechanical properties such as hardness, abrasion resistance, tensile strength, and elongation at break compared to those not containing silane. The rubber nanocomposite with silane demonstrated better thermal aging properties than rubber nanocomposite without silane at any given filler loading. The optimal level of CNCs filled in rubber nanocomposite containing Si-69 was 1 phr, which was further validated by examining its dynamic mechanical characteristics and phase morphology. Mechanical characteristics were poor at high levels of CNCs (greater than 1 phr) due to phase separation and filler agglomeration in the rubber nanocomposites. Furthermore, incorporation of 1 phr CNCs in rubber nanocomposites with silane improved ozone aging and thermal stability of the rubber nanocomposites.

Biodegradable Plasticizer from Cardanol via Acid-Free Catalysis of Quaternary Ammonium Phosphotungstate

The most widely used phthalic ester plasticizers are reproductive toxic and nonbiodegradable. Developing biodegradable plasticizers from biomass resources remains a great challenge for the enrichment and pollution of plasticizers that seriously damage the environment. In this study, a biodegradable plasticizer (CEPT, cardanol-based epoxy plasticizer containing a triazine ring) was fabricated and derived from cardanol via acid-free catalysis. Subsequently, the essential performances, including mechanical properties, thermal degradation, thermal aging properties, solvent extraction resistance, and the microstructure of polyvinyl chloride plasticized with CEPT, were investigated. The mechanism behind these performances was explored. In addition, the biodegradability of CEPT was studied in active soil and in the Tenebrio molitor digestive system. The degradation products were obtained from the two research systems and characterized via Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, electrospray ionization mass spectrometry, and gas chromatography–mass spectrometry. The results illustrated that CEPT did undergo biodegradation and produced small-molecular components. The insect degradation method of biomass plasticizers proposed an original and available strategy for prevention of the pollution problem of plasticizers.

Sustainable plasticizer from agroindustrial waste for natural rubber compounds: Influence on the curing system and compound properties

The industry has pursued efforts to minimize the use of fossil fuel-based processing oils in favor of naturally occurring nontoxic oils from renewable sources, such as vegetable oils. In this study, the feasibility of replacing naphthenic oil (NAPH)-based plasticizers in natural rubber (NR) compounds with oil originating from cashew nut shells was evaluated. Cardanol oil (Cdn), which is derived from decarboxylated cashew nut shell liquid, a byproduct of cashew nut production, was chemically modified by acetylation and named Cdn-A. The successful acetylation of Cdn with acetic anhydride was confirmed. The effects of Cdn and Cdn-A as plasticizers on the curing characteristics, thermal aging, and physical, mechanical, and dynamic properties of carbon black-filled NR compounds were then evaluated. Cdn acted as a co-activator for rubber vulcanization; by contrast, Cdn-A showed negligible effects on this process. Vulcanized Cdn- and Cdn-A-containing NR compounds exhibited improved abrasion and tear resistance compared with the reference compound containing NAPH, as well as antioxidant activity. The Cdn-added NR compound also demonstrated high elongation at break and toughness. The results collectively suggest that NR compounds containing Cdn exhibit properties suitable for tire tread applications requiring high grip characteristics.

Thermal Aging Properties of 500 kV AC and DC XLPE Cable Insulation Materials.

Despite similar material composition and insulation application, the alternating current (AC) cross-linked polyethylene (XLPE) and direct current (DC) XLPE materials cannot replace each other due to different voltage forms. Herein, this work presents a systematical investigation into the effects of thermal aging on the material composition and properties of 500 kV-level commercial AC XLPE and DC XLPE materials. A higher content of antioxidants in the AC XLPE than in the DC XLPE was experimentally demonstrated via thermal analysis technologies, such as oxidation-induced time and oxidation-induced temperature. Retarded thermal oxidation and suppression of space charge effects were observed in thermally aged AC XLPE samples. On the other hand, the carbonyl index of DC XLPE dramatically rose when thermal aging was up to 168 h. The newly generated oxygen-containing groups provided deep trapping sites (~0.95 eV) for space charges and caused severe electric field distortion (120%) under -50 kV/mm at room temperature in the aged DC XLPE samples. For the unaged XLPE materials, the positive space charge packets were attributed to the residue crosslinking byproducts, even after being treated in vacuum at 70 °C for 24 h. Thus, it was reasoned that the DC XLPE material had a lower crosslinking degree to guarantee fewer crosslinking byproducts. This work offers a simple but accurate method for evaluating thermal oxidation resistance and space charge properties crucial for developing high-performance HVDC cable insulation materials.

Aging phenomena in non-crosslinked polyolefin blend cable insulation material: Electrical treeing and thermal aging.

Non-crosslinked polyolefin blends have become a favorable alternative material to crosslinked polyethylene (XLPE) cable insulation owing to their low power consumption in the production process and good recyclability at the end of service life. Although studies on non-crosslinked materials have achieved significant results, the electrical and thermal aging properties of these materials undeniably need extensive research attention and systematic exploration. Aging performance is directly related to the lifetime and reliability of cables. In this study, the electrical treeing and thermal aging phenomena of 70wt.% linear low-density polyethylene (LLDPE) and 30wt.% high-density polyethylene (HDPE) blends (abbreviated as 70L-30H) were studied and compared with those of XLPE by investigating the microstructural feature, electrical treeing behavior, and mechanical performance during thermal aging. Electrical treeing tests show that 70L-30H blends exhibited smaller treeing dimensions and lower electrical tree growth rates than those of XLPE. Thermal aging tests exhibit that the mechanical property degradation of 70L-30H blends is less than that of XLPE under the same aging time. Through differential scanning calorimetry analysis and microstructure observation, the 70L-30H blend shows higher melting temperature, thicker lamellae, and higher crystallinity with a uniform and fine spherulite structure, which are responsible for good anti-aging performance. This study indicates that the blends exhibit better electrical and thermal aging resistance than XLPE, which provides a performance guarantee for its further application in the non-crosslinked cable system.

Effect of Thermal Aging on Dynamic Mechanical Performance of a Novel Structural Adhesive

This study mainly evaluates the thermal aging properties of a new room temperature cured structural adhesive. Multiple adhesive specimens were thermal aged at 80℃, 100℃, 120℃ and 140℃, respectively, and subjected to the dynamic mechanical analysis (DMA) at different temperatures and frequencies. According to the results of DMA and thermodynamic analysis, the performance of the adhesive changes little after aging at 80℃, 100℃ and 120℃ for 30 days. However, the adhesive performance became unstable at 140℃, and deteriorated rapidly with the extension of aging time. Hence, this structural adhesive is suitable for the environment below 120℃. In addition, the generalized curve of the structural adhesive aging for 20 days at 100℃ was obtained, following the principles of time-temperature equivalence superposition and time-aging time equivalence superposition. The test time was shortened significantly. This research provides an accelerated characterization strategy for the long-term mechanical properties of other polymers, making it possible to obtain the generalized curve of polymers aging for a specific time at a specific temperature.

Synthesis of high temperature resistant BADCy/PES/BMI resin adhesive by solvent-free method and its performance characterization

A series of high temperature resistant adhesives were synthesis from 2,2’-Bis-(4-cyanatophenyl) (BADCy), polyethersulfone (PES) and N, N’-4,4’-diphenylmethane bismaleimide (BMI) by solvent-free method. The effect of BMI content on the curing behavior, thermal, mechanical, fracture morphology, adhesive and thermal aging properties were studied. With the addition of BMI, the curing activation energy of resin increases from 67.44 kJ/mol of BMI-0 to 69.22 kJ/mol of BMI-30. The reason is mainly due to the higher activation energy of BMI self-polymerization. The BADCy/PES/BMI resin has a wider processing window (BMI-20 has the lowest viscosity in the range of 96°–182 °C), and the processing window becomes wider as the BMI content increases. More interestingly, as BMI content increases, resins toughness decreases and lap shear strength at room temperature decreases (from 31.4 MPa of BMI-0 to 20.0 MPa of BMI-30), but the high temperature performance increases as BMI content increases (temperature for 5% weight loss under N2 atmosphere of BADCy/PES/BMI increase from 404 °C of BMI-0 to 413 °C of BMI-30).