Polymers

Research

14 pages, 5111 KiB

Open AccessArticle

Thermoplastic Vulcanizates with an Integration of High Wear-Resistant and Anti-Slip Properties Based on Styrene Ethylene Propylene Styrene Block Copolymer/Styrene Ethylene Butylene Styrene Block Copolymer/Solution-Polymerization Styrene-Butadiene Rubber

by Zhicheng Li and Jianbin Xiao

Polymers 2024, 16(15), 2221; https://doi.org/10.3390/polym16152221 - 4 Aug 2024

Viewed by 2121

Abstract

Distinguished from traditional vulcanized rubber, which is not reusable, thermoplastic elastomer (TPV) is a material that possesses both the excellent resilience of traditional vulcanized rubber and the recyclability of thermoplastic, and TPVs have been widely studied in both academia and industry because of [...] Read more.

Distinguished from traditional vulcanized rubber, which is not reusable, thermoplastic elastomer (TPV) is a material that possesses both the excellent resilience of traditional vulcanized rubber and the recyclability of thermoplastic, and TPVs have been widely studied in both academia and industry because of their outstanding green properties. In this study, new thermoplastic elastomers based on solution polymerized styrene butadiene rubber (SSBR) and thermoplastic elastomers (SEPSs/SEBSs) were prepared by the first dynamic vulcanization process. The high slip resistance and abrasion resistance of SSBR are utilized to improve the poor slip resistance of SEPSs/SEBSs, which provides a direction for the recycling of shoe sole materials. In this paper, the effects of different ratios of the rubber/plastic phase (R/P) on the mechanical properties, rheological properties, micro-morphology, wear resistance, and anti-slip properties of SSBR/TPE TPVs are investigated. The results show that the SSBR/TPE TPVs have good mechanical properties. The tensile strength, tear strength, hardness, and resilience of the TPVs decrease slightly with an increasing R/P ratio. Still, TPVs have a tensile strength of 18.1 MPa when the ratio of R/P is 40/100, and this reaches the performance of the vulcanized rubber sole materials commonly used in the market. In addition, combined with microscopic morphology analysis (SEM), it was found that, with the increase in the R/P ratio, the size of the rubber particles gradually increased, forming a stronger crosslinking network, but the rheological properties of TPVs gradually decreased; crosslinking network enhancement led to the increase in the size of the rubber particles, and the increase in the size of rubber particles made the material in the abrasion of rubber particles fall easily, thus increasing its abrasion volume. Through dynamic mechanical analysis and anti-slip tests, when the R/P ratio was 40/100, the tan δ of TPVs at 0 °C was 0.35, which represents an ordinary vulcanized rubber sole material in the market. The viscoelasticity of TPVs increased with the increase in the R/P ratio, which improved the anti-slip performance of TPVs. SSBR/TPE TPVs are expected to be used in footwear and automotive fields due to their excellent abrasion resistance and anti-slip performance. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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14 pages, 2886 KiB

Open AccessArticle

Synthesis and Characterization of Negative-Tone Photosensitive Polyimides with Low Coefficient of Thermal Expansion for Packaging Applications

by Peng Zhang, Hehe Wang, Pengcheng Xia, Xiaolei Chen, Wei Zhao, Chengqian Wang, Xiao Meng and Bin Jia

Polymers 2024, 16(13), 1805; https://doi.org/10.3390/polym16131805 - 26 Jun 2024

Cited by 2 | Viewed by 2583

Abstract

Negative-tone photosensitive polyimides (PSPIs) with a low coefficient of thermal expansion (CTE) were prepared by dissolving polyimide precursor-poly(amide ester) (PAE) resins, photoinitiators, photocrosslinkers and other additives in organic solvents. Using triamine as a monomer and dianhydride and diamine as polycondensates, tri-branched structure PAE [...] Read more.

Negative-tone photosensitive polyimides (PSPIs) with a low coefficient of thermal expansion (CTE) were prepared by dissolving polyimide precursor-poly(amide ester) (PAE) resins, photoinitiators, photocrosslinkers and other additives in organic solvents. Using triamine as a monomer and dianhydride and diamine as polycondensates, tri-branched structure PAE resins with different molecular weights named PAE-1~5 were prepared. A series of corresponding PSPI films named PSPI-1~5 were prepared from PAE-1~5 resins with the same formulation, respectively. The PSPI-1~5 films prepared from resins of this structure have excellent mechanical, thermal and electrical properties after being thermally cured at 350 °C/2 h in nitrogen. The PSPI-1~5 films’ coating solution also show good photolithographic performance and are able to obtain photolithographic patterns with a resolution of about 10 μm after homogenization, exposure and development. Among the PSPI-1~5 films, PSPI-2 has the most excellent lithographic properties with a weight average molecular weight (M_w) of 2.9 × 10⁴ g/mol, a CTE of 41 ppk/°C, a glass transition temperature (T_g) of 343 °C and a 5% weight loss temperature (T_d5) of 520 °C, making it suitable for industrial scale-up. The mechanical properties of elongation at breakage of 42.4%, tensile moduli of 3.4 GPa and tensile strength of 153.7 MPa were also measured. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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11 pages, 5122 KiB

Open AccessArticle

Investigation of Creep Behavior of HDPE Pipe Butt Fusion Welded Joints Using a Stepped Isostress Method

by Chunmei Bai, Rong Lin and Huan Sheng Lai

Polymers 2024, 16(13), 1803; https://doi.org/10.3390/polym16131803 - 26 Jun 2024

Cited by 3 | Viewed by 2391

Abstract

The utilization of high-density polyethylene (HDPE) pipes is prevalent in water transportation due to their exceptional durability, resistance to corrosion, and ease of installation. Traditionally, butt fusion welding has been employed to connect HDPE pipes. In this study, scanning electron microscopy (SEM) was [...] Read more.

The utilization of high-density polyethylene (HDPE) pipes is prevalent in water transportation due to their exceptional durability, resistance to corrosion, and ease of installation. Traditionally, butt fusion welding has been employed to connect HDPE pipes. In this study, scanning electron microscopy (SEM) was utilized to examine the microstructure of butt fusion welded joints of HDPE pipes, while the stepped isostress method (SSM) was employed to investigate their creep behavior at 100 °C in ambient air. SEM results revealed a significant presence of craze or lamellae in the base material, whereas minimal occurrences of craze or lamellae were observed in the melt zone. The results obtained from the SSM indicated that the creep life of butt fusion welded joints of HDPE pipes was not adversely affected by the welding bead, and their creep life was no less than that of the base material when ductile creep failure occurred. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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13 pages, 4984 KiB

Open AccessArticle

Structural, Optical, and Thermal Properties of PVA/SrTiO₃/CNT Polymer Nanocomposites

by Alhulw H. Alshammari

Polymers 2024, 16(10), 1392; https://doi.org/10.3390/polym16101392 - 14 May 2024

Cited by 12 | Viewed by 1926

Abstract

Successful preparation of PVA/SrTiO₃/CNT polymer nanocomposite films was accomplished via the solution casting method. The structural, optical, and thermal properties of the films were tested by XRD, SEM, FTIR, TGA, and UV-visible spectroscopy. Inclusion of the SrTiO₃/CNT nanofillers with [...] Read more.

Successful preparation of PVA/SrTiO₃/CNT polymer nanocomposite films was accomplished via the solution casting method. The structural, optical, and thermal properties of the films were tested by XRD, SEM, FTIR, TGA, and UV-visible spectroscopy. Inclusion of the SrTiO₃/CNT nanofillers with a maximum of 1 wt% drastically improved the optical and thermal properties of PVA films. SrTiO₃ has a cubic crystal structure, and its average crystal size was found to be 28.75 nm. SEM images showed uniform distribution in the sample with 0.3 wt% of SrTiO₃/CNTs in the PVA film, while some agglomerations appeared in the samples of higher SrTiO₃/CNT content, i.e., at 0.7 and 1.0 wt%, in the PVA polymer films. The inclusion of SrTiO₃/CNTs improved the thermal stability of PVA polymer films. The direct and indirect optical band gaps of the PVA films decreased when increasing the mass of the SrTiO₃/CNTs, while the single-oscillator energy (E₀) and dispersion energy (E_d) increased. The films’ refractive indices were gradually increased upon increasing the nanofillers’ weight. In addition, improvements in the optical susceptibility and nonlinear refractive indices’ values were also obtained. These films are qualified for optoelectronic applications due to their distinct optical and thermal properties. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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14 pages, 4256 KiB

Open AccessArticle

Synthesis and Properties of Bio-Based Polycarbonates Containing Silicone Blocks

by Mengjuan Liu, Hui Wang, Wei Fang, Tao Lu, Jinsen Wang and Guozhang Wu

Polymers 2024, 16(10), 1318; https://doi.org/10.3390/polym16101318 - 8 May 2024

Viewed by 2068

Abstract

This study aims to investigate the effects of different hydroxy-terminated silicones on the properties of polycarbonate-silicone copolymers (ICS-PC) by introducing flexible and hydrophobic silicone into isosorbide-based polycarbonate through melt transesterification- polycondensation method. Through compatibility and transesterification experiments, it is confirmed that the alcohol-hydroxyl [...] Read more.

This study aims to investigate the effects of different hydroxy-terminated silicones on the properties of polycarbonate-silicone copolymers (ICS-PC) by introducing flexible and hydrophobic silicone into isosorbide-based polycarbonate through melt transesterification- polycondensation method. Through compatibility and transesterification experiments, it is confirmed that the alcohol-hydroxyl polydimethylsiloxane (a-PDMS) has higher reactivity and silicone conversion than the phenol-hydroxyl polydimethylsiloxane (p-PDMS), but the conversion does not exceed 81%. Polyether-modified silicone (PEMS) exhibits better compatibility and higher reactivity, thus resulting in higher conversion that can reach 86%. Effects of the type and content of silicone on the glass transition temperature (T_g), optical transparency, saturated water absorption, and mechanical strength of ICS-PCs were also discussed. It is found that p-PDMS has higher T_g, hydrophobicity, and mechanical strength with similar silicone content, but the total transmittance does not exceed 60%. In contrast, the PEMS system exhibits better optical transparency due to its improved compatibility with the PC matrix, with a total transmittance of up to 73%, T_g exceeding 150 °C while maintaining excellent flexibility and hydrophobicity. These results are helpful to further improve the comprehensive properties of bio-based polycarbonates. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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20 pages, 3567 KiB

Open AccessArticle

Toward the Rational Design of Organic Catalysts for Organocatalysed Atom Transfer Radical Polymerisation

by Zhilei Wang, Chenyu Wu and Wenjian Liu

Polymers 2024, 16(3), 323; https://doi.org/10.3390/polym16030323 - 24 Jan 2024

Cited by 2 | Viewed by 1402

Abstract

Thanks to their diversity, organic photocatalysts (PCs) have been widely used in manufacturing polymeric products with well-defined molecular weights, block sequences, and architectures. Still, however, more universal property-performance relationships are needed to enable the rational design of such PCs. That is, a set [...] Read more.

Thanks to their diversity, organic photocatalysts (PCs) have been widely used in manufacturing polymeric products with well-defined molecular weights, block sequences, and architectures. Still, however, more universal property-performance relationships are needed to enable the rational design of such PCs. That is, a set of unique descriptors ought to be identified to represent key properties of the PCs relevant for polymerisation. Previously, the redox potentials of excited PCs (PC^*) were used as a good descriptor for characterising very structurally similar PCs. However, it fails to elucidate PCs with diverse chromophore cores and ligands, among which those used for polymerisation are a good representative. As showcased by model systems of organocatalysed atom transfer radical polymerisation (O-ATRP), new universal descriptors accounting for additional factors, such as the binding and density overlap between the PC^* and initiator, are proposed and proved to be successful in elucidating the experimental performances of PCs in polymerisation. While O-ATRP is exemplified here, the approach adopted is general for studying other photocatalytic systems. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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14 pages, 5730 KiB

Open AccessArticle

Effect of Cooling Temperature on Crystalline Behavior of Polyphenylene Sulfide/Glass Fiber Composites

by Seo-Hwa Hong and Beom-Gon Cho

Polymers 2023, 15(15), 3179; https://doi.org/10.3390/polym15153179 - 26 Jul 2023

Cited by 2 | Viewed by 2279

Abstract

Poly (phenylene sulfide) (PPS) is a super engineering plastic that has not only excellent rigidity and high chemical resistance but also excellent electrical insulation properties; therefore, it can be applied as an electronic cover or an overheating prevention component. This plastic has been [...] Read more.

Poly (phenylene sulfide) (PPS) is a super engineering plastic that has not only excellent rigidity and high chemical resistance but also excellent electrical insulation properties; therefore, it can be applied as an electronic cover or an overheating prevention component. This plastic has been extensively applied in the manufacture of capacitor housing as, in addition to being a functional and lightweight material, it has a safety feature that can block the electrical connection between the electrolyte inside and outside the capacitor. Moreover, the fabrication of PPS composites with high glass fiber (GF) content facilitates the development of lightweight and excellent future materials, which widens the scope of the application of this polymer. However, the crystallinity and mechanical properties of PPS/GF composites have been found to vary depending on the cooling temperature. Although extensive studies have been conducted on the influence of cooling temperature on the crystalline behavior of PPS-based composites, there has been limited research focused particularly on PPS/GF composites for capacitor housing applications. In this study, to apply PPS/GF composites as film capacitor housings, specimens were prepared via injection molding at different cooling temperatures to investigate the composites’ tensile, flexural, and impact energy absorption properties resulting in increases in mechanical properties at high cooling mold temperature. Fracture surface analysis was also performed on the fractured specimens after the impact test to confirm the orientation of the GF and the shape of the micropores. Finally, the crystallinity of the composites increased with higher cooling temperatures due to the extended crystallization time. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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17 pages, 5253 KiB

Open AccessArticle

Carbon Nanotube-Based Intumescent Flame Retardants Achieve High-Efficiency Flame Retardancy and Simultaneously Avoid Mechanical Property Loss

by Qi Qu, Jin Xu, Huanhuan Wang, Yinrui Yu, Qianpeng Dong, Xianhua Zhang and Yan He

Polymers 2023, 15(6), 1406; https://doi.org/10.3390/polym15061406 - 11 Mar 2023

Cited by 14 | Viewed by 3060

Abstract

Intumescent flame retardants (IFR) are an excellent solution to the problem of easy combustion of polymers. Still, the negative effect of the addition of flame retardants is the decline of the mechanical properties of polymers. In this context, carbon nanotubes (CNTs) are modified [...] Read more.

Intumescent flame retardants (IFR) are an excellent solution to the problem of easy combustion of polymers. Still, the negative effect of the addition of flame retardants is the decline of the mechanical properties of polymers. In this context, carbon nanotubes (CNTs) are modified with tannic acid (TA) and then wrapped on the surface of ammonium polyphosphate (APP) to construct a special intumescent flame retardant structure (CTAPP). The respective advantages of the three components in the structure are explained in detail, especially the role of CNTs with high thermal conductivity in the flame retardant system. Compared with pure natural rubber (NR), the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of the composites proposed with special structural flame retardants are decreased by 68.4%, 64.3%, and 49.3%, respectively, while the limiting oxygen index (LOI) increased to 28.6%. The TA-modified CNTs wrapped on the surface of APP can effectively reduce the mechanical damage caused by the flame retardant to the polymer. To sum up, the flame retardant structure of TA-modified CNTs wrapped on APP can effectively enhance the flame retardant properties of the NR matrix and reduce the negative impact on mechanics caused by adding APP flame retardant. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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11 pages, 1492 KiB

Open AccessArticle

Influence of Acetone and Primer on Strength and Ductility of Chlorinated Poly(vinyl chloride)

by Hanlin Mi, Xiaokang Huang and Pean-Yue Ben Jar

Polymers 2023, 15(3), 489; https://doi.org/10.3390/polym15030489 - 17 Jan 2023

Cited by 2 | Viewed by 2273

Abstract

Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The study examined the influences of primer and its major component, acetone, on CPVC’s mechanical properties. Two types of CPVC product, sheet and pipe, were used in the mechanical testing. [...] Read more.

Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The study examined the influences of primer and its major component, acetone, on CPVC’s mechanical properties. Two types of CPVC product, sheet and pipe, were used in the mechanical testing. Sheet specimens were immersed in acetone or primer for 40 and 10 min, respectively, i.e., the maximum allowable time without mass loss, and then dried in air before the mechanical testing. Pipe (ring) specimens were treated either through immersion in acetone or primer for 30 min or in contact with these solvents locally on the inner surface for 2.5 h, and then air dried for 10.5 days before the mechanical testing. Results showed that CPVC’s strength decreased after the absorption of these solvents, and air dry could remove acetone but not completely primer. The study also showed that pipe specimens by local contact with primer could generate brittle fracture. In view that sheet specimens always fractured in a ductile manner, brittle fracture of the pipe specimens could not be caused by CPVC degradation. Rather, strength decrease in the local region could provide a plausible explanation for the brittle fracture behavior, though further investigation is needed. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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17 pages, 4763 KiB

Open AccessArticle

Study on Experiment and Simulation of Shear Force on Membrane with Dynamic Cross-Flow for Lignin in Black Liquor

by Wenjie Zhao, Yu Wang and Qingdang Li

Polymers 2023, 15(2), 380; https://doi.org/10.3390/polym15020380 - 11 Jan 2023

Cited by 3 | Viewed by 2048

Abstract

To address the problem of lignin membrane fouling caused by dynamic cross-flow in the process of retaining and concentrating the black liquor byproduct of papermaking, this paper uses three different rotating structures (vane, disk and propeller) to increase the surface shear force and [...] Read more.

To address the problem of lignin membrane fouling caused by dynamic cross-flow in the process of retaining and concentrating the black liquor byproduct of papermaking, this paper uses three different rotating structures (vane, disk and propeller) to increase the surface shear force and filtration flux of the membrane. In this paper, under different rotating speeds and different transmembrane pressure differences, numerical simulations were conducted on the shear forces generated by the three structures and the retention process on the surface of the membrane. The variation laws were also studied and compared. Under the same filtration conditions, the vane structure demonstrates better results than the propeller and disk structures in terms of increasing filtration flux. Based on the result, the vane shear force was simulated in terms of changing the particle deposition, and compared with vane rotating speeds of 100–700 r/min, the surface particle deposition of the membrane was significantly reduced at a rotating speed of 800 r/min. Finally, the numerical simulation results were experimentally validated to ensure the accuracy of the simulation. The findings provide a theoretical basis and practical value for solving the problem of lignin membrane fouling caused by dynamic cross-flow in the process of retaining and concentrating the black liquor byproduct of papermaking. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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18 pages, 11260 KiB

Open AccessArticle

Effects of Different Metals on Properties and Friction and Wear of Composite Materials

by Wei Li and Yihui Chen

Polymers 2022, 14(21), 4545; https://doi.org/10.3390/polym14214545 - 26 Oct 2022

Cited by 1 | Viewed by 1827

Abstract

With the vigorous development of the automobile industry, the rubber industry has also made continuous progress. As necessary mixing equipment in the rubber industry, the internal mixer is required to undertake a lot of constant work for a long time, which inevitably causes [...] Read more.

With the vigorous development of the automobile industry, the rubber industry has also made continuous progress. As necessary mixing equipment in the rubber industry, the internal mixer is required to undertake a lot of constant work for a long time, which inevitably causes wear to the internal mixer. On the one hand, the wear of the metal on the end face of the internal mixer will lead to an increase in the gap between the inner mixing chamber and the end face, which will lead to material leakage, affect the material ratio of the rubber mixture, and ultimately affect the performance of the rubber mixture. On the other hand, the wear of the end metal of the internal mixer is an increasing process, and the tiny metal particles of the end metal will be incorporated into the rubber mix along with the mixing process, affecting the performance of the rubber mix. At the same time, the disassembly and repair of the internal mixer are complex, and the end face maintenance is difficult. Therefore, finding a kind of end face metal with good wear resistance, long service life, and no influence on rubber compound performance is essential. This paper takes the end face metal of the internal mixer with severe wear as the research object. The wear degree of the metal after friction between MCYD-4 alloy, YW-15 alloy, wear-resistant stainless steel, tungsten carbide alloy, and the rubber compound is compared. The changes in the properties of the compounds after rubbing were investigated. The study found that the tensile tear properties, wet skid resistance, and rolling resistance of NR/BR composites differed when different end-face metals were selected for mixing, but the gap was small. When the end-face metal is YW-15 alloy, the NR/BR composites have the best dispersibility, the most robust tensile tear performance, the best wet-skid resistance, and minor rolling resistance. When the end face metal is the other three alloys, the physical and mechanical properties of the NR/BR composites are reduced to different extents. In this paper, starting from the actual working conditions, considering both abrasive wear and corrosive wear, the friction and wear between the rubber compound and the four kinds of metals commonly used on the end face of the internal mixer are studied. The metal that has little effect on the performance of the rubber compound and is the most wear-resistant was found. This paper is of great significance for improving production efficiency and prolonging the life of the internal mixer. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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23 pages, 7716 KiB

Open AccessArticle

Effect of Wet Mixing on Properties of Radial-Orientation Basalt Fiber-Reinforced Rubber Compounds

by Benhui Yu, Jing Wang, Kongshuo Wang, Deshang Han, Jianbin Ren, Dewei Zhang and Chuansheng Wang

Polymers 2022, 14(20), 4422; https://doi.org/10.3390/polym14204422 - 19 Oct 2022

Cited by 4 | Viewed by 1938

Abstract

The effects of wet mixing and traditional mixing on the properties of radial-orientation basalt fiber-reinforced rubber products were studied through experiments. The results show that compared with traditional mixing, the basalt fibers under the wet mixing conditions can more effectively enhance the physical [...] Read more.

The effects of wet mixing and traditional mixing on the properties of radial-orientation basalt fiber-reinforced rubber products were studied through experiments. The results show that compared with traditional mixing, the basalt fibers under the wet mixing conditions can more effectively enhance the physical and mechanical properties of composites. The properties of the composites, such as carbon black dispersion, filler dispersion, rolling resistance and wet-sliding resistance, were the best after the latex and carbon black were premixed and then mixed by a mixer. Through extrusion experiments with the developed short-fiber radial-orientation die, it can be found that the fluidity of composites after extrusion is enhanced. Through analysis utilizing an electron microscope, it is shown that when the BFs added with KH550 (3-Aminopropyltriethoxysilane) were modified by KH560 ((3-Glycidyloxypropyl)trimethoxysilane), the interface layers of BF (basalt fiber)–KH560–NR and BF–KH550–NR were formed, which improves the adhesion between BFs and the rubber matrix. Qualitative characterization experiments on the orientation direction of the vulcanized composites were carried out through the experiments; that is, the qualitative characterization experiments on the segmented cutting and vulcanization of the composites in the radial direction showed that the short-fiber radial-orientation die could greatly improve the radial orientation degree of the short fibers in the radial direction. After adding KH560, the performance of the composites reinforced by the short fibers was improved to a certain extent compared with those without KH560. By adding DZ (N,N-Dicyclohexyl-2-benzothiazolsulfene amide) and CTP(cytidine triphosphate disodium) into the vulcanization system, the curing process of compounds in mixing and extrusion was delayed and the scorching resistance of short-fiber-reinforced composites was enhanced. Under the same conditions, the properties of the compounds after extrusion were greatly improved compared with those without extrusion. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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9 pages, 4168 KiB

Open AccessArticle

The Effect of Welding Defects on the Long-Term Performance of HDPE Pipes

by Huansheng Lai, Dengshuai Fan and Kanglin Liu

Polymers 2022, 14(19), 3936; https://doi.org/10.3390/polym14193936 - 21 Sep 2022

Cited by 11 | Viewed by 4435

Abstract

High-density polyethylene (HDPE) pipes are the preferred pipes of water systems in nuclear power plants because they are durable, corrosion-free, easy to install, and not subject to fouling. However, their long-term performance can be affected by welding defects. In this paper, the effect [...] Read more.

High-density polyethylene (HDPE) pipes are the preferred pipes of water systems in nuclear power plants because they are durable, corrosion-free, easy to install, and not subject to fouling. However, their long-term performance can be affected by welding defects. In this paper, the effect of welding defects on the long-term performance of HDPE pipe butt fusion joints was studied using a creep test. A welding defect with a hole or inclusion in the joint was simulated by artificially inserting a copper ball during butt fusion welding. The test results showed that the creep life of the joint decreased with increased defect size. An expression describing the creep life and the defect ratio was obtained according to the test results. In addition, the test results showed that the creep life of the joint without a welding bead was about 50% of that in a joint with a welding bead. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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19 pages, 10925 KiB

Open AccessArticle

Influence of the Synergistic Effect of Multi-Walled Carbon Nanotubes and Carbon Fibers in the Rubber Matrix on the Friction and Wear of Metals during the Mixing Process

by Lin Wang, Yi Pan, Yihui Chen, Jian Qiu, Aihua Du, Deshang Han and Chuansheng Wang

Polymers 2022, 14(18), 3731; https://doi.org/10.3390/polym14183731 - 7 Sep 2022

Cited by 2 | Viewed by 1661

Abstract

As a piece of high-intensity running equipment, the wear of an internal mixer determines the quality of rubber and its life. In general, the wear of an internal mixer is caused by the friction between the rubber and metal during the mixing process, [...] Read more.

As a piece of high-intensity running equipment, the wear of an internal mixer determines the quality of rubber and its life. In general, the wear of an internal mixer is caused by the friction between the rubber and metal during the mixing process, and the most severe wear position is the end face of the equipment. In this paper, a mixture of multi-walled carbon nanotubes (MWCNTs) and carbon fibers (CFs) are added to rubber by mechanical compounding to obtain MWCNT/CF/carbon black (CB) composites. By investigating the synergistic mechanism of MWCNTs and CFs, we analyze the effect of the MWCNT/CF ratio on the frictional wear of metal on the end face of the internal mixer. At the microscopic level, MWCNTs and CFs form a spatial meshwork with CB particles through synergistic interactions. The CB particles can be adsorbed on the spatial meshwork to promote the dispersion of CB particles. In addition, the formation of oil film can be slowed down due to the spatial meshwork, which could hinder the spillage of aromatic oil. Meanwhile, the spatial meshwork serves as a physical isolation layer between the rubber and metal to reduce friction. Therefore, it dramatically impacts the dispersion degree of CB particles, the friction coefficient, the roughness of the surface, and the wear of metal. It shows that the synergistic effect of MWCNT/CF and CB particles is best when the CF content of the rubber matrix is 5 phr, showing the most stable spatial network structure, the best dispersion of CB particles, and minor wear on the end face of the internal mixer. Full article

(This article belongs to the Special Issue Advances in Structure-Property Relationship of Polymer Materials)

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