Dicumyl Peroxide Research Articles

Lignin Reinforcement in Polybutylene Succinate Copolymers

This study investigated the valorization of industrial lignin for producing biodegradable polybutylene succinate (PBS)–lignin copolymers. PBS was blended with varying lignin contents (0–45 wt. %) and crosslinked/grafted using dicumyl peroxide (DCP). The preparation of the copolymers by reactive extrusion was successful, with mechanical, thermal, and morphological properties comprehensively analyzed. Lignin addition decreased tensile strength but improved stiffness (modulus) and thermal stability. Crosslinking with DCP improved the interfacial adhesion between PBS and lignin, resulting in better flexural performance at moderate lignin levels. Differential scanning calorimetry showed that lignin initially improved the crystallization temperature, but hindered it at higher concentrations due to its rigid, aromatic structure. Scanning electron microscopy analysis showed poor interfacial adhesion in PBS–lignin blends, but the surface morphology improved in crosslinked PBS–lignin copolymers, with less phase separation observed. An optimal lignin concentration appeared to depend on the property of interest. While 30% lignin provided the best improvement in flexural strength, 20% lignin offered a more balanced enhancement for most properties without the severe reduction in tensile strength observed at higher lignin contents.

A novel compatibilizer obtained from olive pomace oil maleate (OPOMA) and evaluation in PLA composite production

Alternative of using organic and biomass residues as additives or reinforcements in the production of composite materials has attracted great attention since the 2000s. However, when lignocellulosic biomass is used as natural fiber in composite production, it may have some disadvantages such as low interfacial bonding with the matrix phase. The most common methods used to strengthen the bonding between the matrix phase and the additive material is to use maleic anhydride (MA) as a compatibilizer and some chemicals such as dicumyl peroxide (DCP) as reaction initiators to increase the compatibilizing effect of MA. Therefore, in this study, olive pomace oil maleate (OPOMA) was prepared to be used in the production of PLA (polylactic acid) composites. Olive pomace obtained with ionic liquid pretreatment (OP-IL) in the previous studies of the authors and OPOMA were used in composite production with a biodegradable polymer of PLA. The composite was obtained by mixing 95PLA+5OP-IL by weight in twin-screw extruder at 190ºC for 10 minutes. Under the same conditions, the effect of OPOMA was evaluated by adding 0.5%, 1% and 2% ratio to PLA + OP-IL. In FTIR spectrum of OPOMA, a new symmetrical and asymmetric C=O bands were formed differently from olive oil. While the tensile strength of the PLA+OP mixture was approximately 10 MPa; the tensile strength value of PLA+OP-IL and PLA+OP-IL+OPOMA was around 60 MPa. The elasticity modulus showed less change compared to other mechanical properties. To conclude, it can be emphasized that oil maleates of lignocellulosic biomasses can be promising compatibilizer for biodegradable composite matrices.

Mechanical Decrosslinking and Reprocessing of Crosslinked Rotomolded Polypropylene Using Cryogenic-Assisted Shear Pulverization and Compression Molding

This paper presents a novel recycling approach for porous/foamed crosslinked rotomolded polypropylene (xPP) parts, originally designed for lightweight and thermal insulation. The method uses a cryogenic-assisted shear pulverization technique to produce parts by compression molding. The part’s final gel content and crosslink density were found to depend on their dicumyl peroxide (DCP) content (0–2.5 phr) and characterized in terms of their chemical, thermal, physical and mechanical properties. The results show that this recycling technique allows for an effective reprocessing of the crosslinked materials since partial decrosslinking occurs. For example, the crosslink density decreased by 64% (3.10 to 1.11 × 10−3 mol/cm3) and the gel content by 9% (84.4% to 71.2%) at 2.5 phr DCP. Reprocessing through compression molding led to a compact and partially crosslinked structure resulting in significant improvements in terms of tensile strength (1480%), tensile modulus (604%), elongation at break (8900%), Shore A hardness (19%) and Shore D hardness (32%) compared to xPP samples (at 2.5 phr). This study paves the way for the development of more sustainable recycling methods, especially for crosslinked polymers, by providing new opportunities to reuse the wastes/end-of-life materials in advanced materials and different applications.

The Network Construction of a New Byproduct-Free XLPE-Based Insulation Using a Click Chemistry-Type Reaction and a Theoretical Study of the Reaction Mechanism.

Cross-linked polyethylene (XLPE) is applied in most advanced high-voltage direct-current (HVDC) power cable insulations, which are produced via dicumyl peroxide (DCP) technology. The electrical conductivity of insulation material can be increased by cross-linking byproducts from the DCP process. Hence, currently much attention is being paid to a new process to produce cross-linking byproduct-free XLPE. The cross-linking in situ between ethylene-glycidyl methacrylate copolymer and 1,5-disubtituted pentane via reactive compounding is a substitute for DCP. The reaction potential energy information of the eighteen reaction channels was obtained at the B3LYP/6-311+G(d,p) level. Results demonstrated that epoxy groups and 1,5-disubtituted reactive groups can react in situ to realize the XLPE-based network structure via covalent linking, and epoxy ring openings yielded ester. 1,5-disubtituted pentane played a cross-linker role. The reactivity of the carboxyl group was stronger than that of the sulfydryl or hydroxyl group. The reaction channel RTS1 was more kinetically favorable due to the lower reaction Gibbs energy barrier height of 1.95 eV. The cross-linking network construction of the new XLPE insulation without byproducts opens up the possibility of DCP substitution, which is beneficial to furthering the design of thermoplastic insulation materials for power cables in the future.

Thermal and radiation effects on the cross-linking and mechanical properties of HNBR elastomers

This study investigates the enhancement of the properties of mixtures based on hydrogenated butadiene nitrile rubber (HNBR) under thermal, radiation and thermo-radiation effects by introducing into them the composition of chlorine-containing triazine and peroxide compounds (HCPX and ABTST) into the composition. It has been shown that radiation-chemical cross-linking and the formation of effective chemical cross-links in HNBR depend both on the absorbed dose of radiation and on the addition of vulcanizing agents. It has been established that the activity of hexachloroparaxylene (HCPX), dicumyl peroxide (DP) and triazine (ABTST) is not the same; the content of the gel increases markedly with increasing absorbed dose. A higher crosslinking density is observed for images subjected to thermo-radiation crosslinking. The change in the molecular structure of HNBR, observed both during heating and irradiation, has the same nature. It has been shown that the physical and mechanical properties of saturated radiation and thermal vulcanizates are practically inferior to thermo-radiation ones in strength.

PHYSICAL-MECHANICAL PROPERTIES OF DYNAMICALLY VULCANIZED BASALT CONTAINING PLASTICS BASED ON COMPATIBILIZED POLYPROPYLENE

The influence of the content of basalt and Exxelor PО1020 compatibilizer on the main physical-mechanical and thermophysical characteristics of composites based on polypropylene is considered. It has been established that the use of a compatibilizer in an amount of 1.0–3.0 wt. % can significantly improve such properties of basalt plastics as tensile strength, yield strength, elongation at break, flexural strength, Vicat softening temperature, and melt flow rate. The possibility of cross-linking basalt plastics with sulfur and dicumyl peroxide is considered, and their role in changing their basic physical-mechanical parameters is determined. A theoretical analysis is given of the formation of an interfacial region with the participation of a compatibilizer and basalt. A micrograph showing the redistribution of basalt in the composition of compatibilized polypropylene is given by electron microscopy. The optimal concentrations of vulcanizing agents are determined, at which the highest strength properties are achieved, provided that elongation at break and the melt flow rate are maintained at a satisfactory level. It has been established that the optimal content of dicumyl peroxide is 0.25–0.5% wt

Cinnamon oil value addition in natural rubber latex‐organic peroxide vulcanization system

AbstractNatural rubber is a sustainable material which plays a vital role in a wide variety of applications. Value additions to this natural material enhance its horizons of utilization and encompass multiple advantages. This endeavor focuses on elevating the properties of the natural rubber latex (NRL)‐dicumyl peroxide vulcanization system with the utilization of cinnamon oil (CIN‐OIL). CIN‐OIL was characterized by GCMS, FTIR, and UV–Vis. The FTIR and TGA have confirmed the incorporation of the CIN‐OIL into the NRL. Swelling studies confirmed that the addition of CIN‐OIL has not interfered with the process of peroxy crosslinking. The adhesive peel test and facial tissue test clearly concluded that CIN‐OIL has reduced the initial tackiness of the material which is apparent in peroxy NR vulcanizates. Tear strength and modulus values were increased with CIN‐OIL due to the formation of physical crosslinking. Weathering tests confirmed the higher degradability of the CIN‐OIL‐added NRL samples. Furthermore, films were tested positive for antibacterial activity against both gram‐positive and gram‐negative bacteria. Along with the enhanced degradability, antibacterial activity, reduced initial tackiness, and enhanced mechanical properties, CIN‐OIL in NRL has enriched its qualities.

High-performance volatile organic compounds free silica-filled butadiene rubber green nanocomposites using ionic liquid peroxide vulcanization

Manufacturing green rubber nanocomposites with higher performance and without volatile organic compounds (VOCs) is a big bottleneck for academics and the industry. Bis(3-triethoxysilylpropyl) tetra sulfide or Si69 silane is the most commonly used for green tires while during tire production it releases VOCs which are dangerous for people's health. Herein we elucidate that ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate can mediate physical and chemical reactions among silica and butadiene rubber (BR) and replace Si69 to fabricating rubber nanocomposites with free VOCs cured by Di cumyl peroxide (DCP). The findings reveal that IL chemically reacts with BR and that combining IL and Si69 shows similar tensile properties (φ = 0.079- 0.147) and higher strain at break in comparison with that containing Si69. Moreover, IL synergistically impacts silica-filled BR nanocomposites viscoelastic, thermal, and dielectric properties. It influences the Payne effect by reducing loss modulus improving weak strain overshoot markedly (the ΔG''/G''0 and tanδ0 values of the vulcanizate containing IL/Si69 are 465% higher and 42.8% lower than that containing Si69) and thermal stability and dielectric properties. Compared with BR nanocomposites containing Si69 at the same amount, IL significantly reduces the tangent value and dissipation energy, providing a simple method to fabricate green rubber nanocomposites with tunable reinforcement behaviors.

Oligomerization of Fischer-Tropsch Olefins by Radical Initiation Method for Synthesizing Poly Olefin Base Oils

In the present work we have investigated the oligomerization process of Fischer-Tropsch synthesis products – gasoline (C5-C10) and diesel (C11-C18) hydrocarbon fractions with a total olefin content (consisting mainly olefins with a branched isomeric chain) of 79.3 and 31.8 wt.%, respectively. Oligomerization was carried out by radical initiation method using azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide and methyl ethyl ketone peroxide (Butanox M-50) as initiators. It was established that the yield of the oligomerization process depending on the initiator used decreases in the following order: azobisisobutyronitrile > benzoyl peroxide > dicumyl peroxide > Butanox M-50. It was determined that when the oligomerization is carried out in polar solvents such as acetone and dichloromethane the yield of product increases by ~2.1 and ~1.7 times, respectively, while at the same time adding a non-polar solvent such as tetrachloromethane to the reaction mixture decreases the product yield by ~2.0 times. The optimal technological parameters for carrying out oligomerization process of synthetic gasoline and diesel fractions were determined: where azobisisobutyronitrile, content 0.5 wt.%., is used as an initiator, acetone as solvent, with reaction temperature of 200 °C, and duration of 12 hrs. under inert atmosphere. The product yield from the diesel fraction is 39.5 %, and from the synthetic gasoline fraction – 36.0 %. At the same time, in terms of characteristics, the oligomerization product of the diesel fraction showed properties similar to commercially available Base oil 3cSt (Group III), and the gasoline fraction showed properties on par with the commercially produced PAO-2 (Group IV). Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Evolution from micropinned to polymeric alloy structure of XLPE‐PS: Improving electrical properties and mechanism

AbstractThis research investigates the transition from a micropinned to a polymeric alloy structure in crosslinked‐polyethylene‐polystyrene (XLPE‐PS). Incorporating 2 wt% 10 μm PS particles into low‐density polyethylene (LDPE) and crosslinking with 2 wt% dicumyl peroxide (DCP) forms XLPE‐PS structures. The polymeric alloy structure, formed at 220°C extrusion, contrasts with the micropinned formed at 150°C. Morphological, thermo‐structural, chemical, and crystal properties are examined to understand their impact on electrical properties and charge transport mechanisms. Results indicate that the polymeric alloy effectively resolves void/crack issues, whereas the micropinned exhibits phase separation. Both structures exhibit a benzene‐crosslinked network, and variations in these structures lead to significant changes in thermo‐structural, chemical, and crystalline properties. The polymeric alloy XLPE‐PS shifts the polyethylene (PE) hkl crystal planes, confirming phase shift and optimal alloying. The structural alterations reveal deeper traps and higher densities in the polymeric alloy XLPE‐PS, leading to significantly improved electrical properties, including reduced DC conductivity by up to 1.3 and 0.7 decades at 30 and 90°C, and increased DC breakdown strength by up to 40.34% and 16.17% at 30 and 90°C, respectively, compared with micropinned XLPE‐PS. This research offers insights into stable high‐voltage insulation development.

Toughening Polylactic Acid with Epoxidized Natural Rubber via Altering the Dicumyl Peroxide Mixing Sequence

Toughening Polylactic Acid with Epoxidized Natural Rubber via Altering the Dicumyl Peroxide Mixing Sequence

Ethylene-Propylene-Methylene/Isoprene Rubber/SiO2 Nanocomposites with Enhanced Mechanical Performances and Deformation Recovery Ability by a Combination of Synchronously Vulcanizing and Nanoparticle Reinforcement.

It is highly desired yet challenging to develop advanced elastomers with excellent mechanical properties, including high strength and toughness. In this work, strong and tough rubber/rubber compound vulcanizates were facilely prepared by blending ethylene-propylene-methylene (EPM) and isoprene rubber (IR) together with dicumyl peroxide (DCP) and subsequent vulcanization, since both EPM and IR can be vulcanized synchronously by DCP and the well-crosslinked structure of EPM/IR vulcanizate presented a stable phase separation state. By tuning their composition, EPM/IR vulcanizates could present remarkably improved mechanical strength and toughness, as well as excellent energy dissipation and deformation recovery abilities. Furthermore, EPM/IR/SiO2 nanocomposites with better properties were prepared by introducing silica nanoparticles into EPM/IR vulcanizates. It was found that the high toughness and strength of EPM/IR vulcanizates and EPM/IR/SiO2 nanocomposites mainly resulted from the combination of stretchability of EPM and strain hardening of IR. Their excellent energy dissipation and deformation recovery abilities were related to the macromolecular characteristics of EPM and IR, compatibility between EPM and IR, and their crosslinking dynamics.

Organic reinforcement of an ethylene propylene diene monomer with the in situ synthesis of a polyimide dispersed phase by reactive extrusion

AbstractEthylene‐propylene‐diene monomer rubber, grafted with maleic anhydride functions (EPDM‐g‐MA) was organically reinforced by reactive extrusion from the in situ synthesis of a polyimide (PI) phase. The blends were reactively processed at 200°C in a twin‐screw extruder, with the PI content varying from 5 to 40 wt%. Transmission Electron Microscopy (TEM) revealed a very fine nodular dispersion of the PI phase with diameters ranging from 130 to 240 nm depending on the PI concentration. The reinforcement of the elastomer was evidenced with a sharp increase of the Young's modulus and the tensile strength, and the stiffness of the material was further increased with the PI content. The linear viscoelastic regime, as measured by the variation in storage modulus as a function of strain, was unaffected by this organic reinforcement, thus opening up an original way of controlling the Payne effect. Additionally, the cross‐linking of the blend with 20 wt% of PI with dicumyl peroxide (DCP) showed that the PI phase did not impact the creation of the cross‐linked network. The decrease of the swelling ratio and the improvement of the elastic recovery suggested that EPDM‐g‐PI copolymers can create a second network in the material, resulting in a higher apparent cross‐linking density. The mechanical properties of the cured blend showed a doubling of the Young's modulus and maximal stress values compared to those obtained for the pure matrix as well as a constant strain at break.Highlights Ethylene‐propylene‐diene monomer rubber, grafted with maleic anhydride functions (EPDM‐g‐MA) was organically reinforced by reactive extrusion. The reinforcement was obtained from the in situ synthesis of a polyimide (PI) phase. The Young's modulus of cross‐linked EPDM containing 20 wt% PI was doubled. The linear viscoelastic regime was unaffected by this organic reinforcement. This original way of reinforcement opens the control of the Payne effect.

Upcycling of recycled polyethylene for rotomolding applications via dicumyl peroxide crosslinking

AbstractPolyethylene (PE), including high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE), makes up a significant part of post‐consumer plastics in municipal solid waste, presenting challenges for traditional recycling methods due to a wide range of melt flow properties and poor interfacial adhesion between the different resin, which often leads to low quality products (downcycling). In this study, a method is proposed to modify the molecular structure of post‐consumer PE (rHDPE and rLDPE) and their blends by using a straightforward organic peroxide crosslinking technique with 1 phr of dicumyl peroxide (DCP). Different rHDPE/rLDPE blend weight ratios (0/100, 20/80, 40/60, 50/50, 60/40, 80/20, and 100/0) were prepared using a combination of co‐rotating twin‐screw extrusion and pulverization. The final parts were produced via rotomolding where both the forming and crosslinking processes occurred concurrently. Subsequently, the materials were characterized in terms of chemical, thermal, and mechanical properties. It was found that the tensile strength (228%), tensile modulus (345%), flexural strength (145%), and flexural modulus (251%) increased by crosslinking the 80% wt. rHDPE (x‐rHDPE). Conversely, the gel content increased by 17%, thermal resistance by 37.2%, and the impact strength by 93% with 80% wt. rLDPE (x‐rLDPE). It can be concluded that a balance between the properties occurs as the addition of DCP improved both the interfacial adhesion and melt properties of rHDPE/rLDPE blends. This innovative approach represents a simple and straightforward method to upcycle mixed plastics (PE) streams, especially for rotomolding applications. It also offers promising avenues for sustainable waste management and material reuse.

Mechanochemical Upcycling of Waste Polypropylene into Warm-Mix Modifier for Asphalt Pavement Incorporating Recycled Concrete Aggregates.

To solve the problems on resource utilization and environmental pollution of waste concrete and waste polypropylene (PP) plastics, the recycling of them into asphalt pavement is a feasible approach. Considering the high melting temperature of waste PP, this study adopted a thermal-and-mechanochemical method to convert waste PP into high-performance warm-mix asphalt modifiers (PPMs) through the hybrid use of dicumyl peroxide (DCP), maleic anhydride (MAH), and epoxidized soybean oil (ESO) for preparing an asphalt mixture (RCAAM) containing recycled concrete aggregate (RCA). For the prepared RCAAM containing PPMs, the mixing temperature was about 30 °C lower than that of the hot-mix RCAAM containing untreated PP. Further, the high-temperature property, low-temperature crack resistance, moisture-induced damage resistance, and fatigue resistance of the RCAAM were characterized. The results indicated that the maximum flexural strain of the RCAAM increased by 7.8~21.4% after using PPMs, while the sectional fractures of the asphalt binder were reduced after damaging at low temperature. The use of ESO in PPMs can promote the cohesion enhancement of the asphalt binder and also improve the high-temperature deformation resistance and fatigue performance of the RCAAM. Notably, the warm-mix epoxidized PPMA mixture worked better close to the hot-mix untreated PPMA mixture, even after the mixing temperature was reduced by 30 °C.

Effect of graphite oxide on the mechanical, thermal, structural and hydrophilicity proprieties of Polypropylene / Poly(Propylene-Glycol) Acrylate / Glycidyl Methacrylate PP/PPGA/GMA composite

This research aims to investigate the synergistic effects of grafting flexible fractions and incorporating reinforcing fillers in polypropylene (PP) matrix. The primary objective is to establish an experimental methodology for preparing and characterizing Polypropylene / Poly(Propylene-Glycol) Acrylate / Glycidyl Methacrylate (PP/PPGA/GMA) composites loaded with graphite oxide (GtO).The process of oxidizing natural graphite powder using a mixture of sulfuric acid and nitric acid was validated through various analytical techniques including IRTF, AFM, DRX, XRF and ATG. The grafting reaction of PPGA and GMA on polypropylene and the incorporation of graphite oxide with varying levels were carried out in the melt state in a Brabender internal mixer; Dicumyl peroxide (DCP) was used as a radical initiator. A comprehensive assessment of the obtained materials was conducted through conventional analyses encompassing mechanical properties (tensile and impact), thermal behaviors (ATG and DSC), morphological characteristics (SEM) and the chemical state of film surfaces (Contact angle).The investigation revealed two key outcomes. Firstly, it showcased the grafting effect of PP on the polymer's morphology and properties. Secondly, it underscored the consequential impact of incorporating graphite oxide on the overall behavior of produced materials.

Solvent-based synthesis, structural elucidation and thermal characterisation of free radical grafted PHBV

This study investigates the solvent-based free-radical graft copolymerization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with C11 (undecenoic acid, UDA), C12 (dodecene, DD), and C18 (octadecene, OD) alkene substrates using dicumyl peroxide as an initiator. Comprehensive Nuclear Magnetic Resonance (NMR) spectroscopy was employed to confirm and quantify grafting, which was achieved at up to 5.8 mol% of monomer units. Thermal analysis revealed a significant reduction in melting temperature for all modified PHBVs, ranging from 10-20°C decrease in comparison to virgin PHBV. A decrease in crystallisation temperature and a reduction in glass transition temperature was measured for the UDA and DD grafted PHBV. Additionally, molecular weight analysis showed a marked decrease in weight average molecular weight (M¯w) and number average molecular weight (M¯n) for PHBV grafted with UDA, which was attributed to the presence of carboxylic acid functionality, which accelerates chain scission. The molecular weight profiles of the dodecene and octadecene grafted PHBV were only marginally reduced (32% and 18% reductions in M¯w, respectively), which is a much less severe reduction than has been previously observed for similar chemistries. Overall, this work demonstrates that solvent-based free-radical graft copolymerization can reduce the melting temperature and disrupt the crystallinity of PHBV, hence improving its processability and progressing the field of PHA modification and application.

Performance Enhancement of Biopolyester Blends by Reactive Compatibilization with Maleic Anhydride-Grafted Poly(butylene succinate-co-adipate).

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging.

Waste ramie fiber/EVA composites with wideband sound-absorbing performance with mixing and foaming process

Increasing noise pollution and ramie fibers waste resource problems need to be solved urgently. In order to resolve the problems, the porous sound-absorbing composites with high sound-absorbing performance were prepared by using waste ramie fibers as reinforcement materials, vinyl acetate copolymer (EVA) as matrix materials, azodicarbonamide(AC) as foaming agent, ZnO as auxiliary foaming agent, and dicumyl peroxide (DCP) as cross-linking agent, which were mixed in a two-stick mixer according to a certain ratio and then hot-pressing process. The process conditions were optimized using single factor analysis. Under the optimal process conditions, the sound-absorbing composites had a maximum sound absorption coefficient (SAC) of 0.72, an average SAC of 0.37, and a noise reduction coefficient (NRC) of 0.41. The sound absorption performance grade reached level III, and the sound absorption performance was excellent in the frequency range of 600 ∼ 6300 Hz. The introduction of foaming agents made the composites with more pores, and the average SAC of foamed composites increased by 346 %(compared with the unfoamed composites). Then, the sound-absorbing mechanism was analyzed. This study presents a novel approach to the recycling and reusing of the waste ramie fibers. It also provides a theoretical and experimental basis for the development of sound-absorbing composites with wider sound absorption band, larger (sound absorption coefficient) SAC and wider application, which is of great significance for sound absorption in the building fields.

Improved Performance of Polylactic Acid Biocomposites at High Lignin Loadings through Glycidyl Methacrylate Grafting of Melt-Flowable Organosolv Lignin.

Glycidyl methacrylate (GMA) was grafted onto a melt-flowable organosolv lignin, called bioleum (BL), using a melt mixing process. Then, up to 40 wt % of BL-g-GMA was blended with polylactic acid (PLA) in the presence of dicumyl peroxide as a free radical initiator utilizing a melt extrusion method. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and tensile testing were performed to characterize the biocomposites' performance. The FTIR results revealed a successful grafting of GMA onto BL. Overall, BL and PLA compatibility increased significantly with the grafting and resulted in decreased domain size of BL-g-GMA and thus enhanced all the tensile properties (strength, modulus, and elongation at break) at BL loadings as high as 40 wt %. For instance, in the biocomposites containing 30 wt % BL, the GMA grafting increased the tensile strength by 23%. The presence of BL and BL-g-GMA hindered PLA's crystallization even when it was cooled at a rate of 1 °C/min. However, the composites with BL-g-GMA showed a crystallinity value comparable to that of PLA during isothermal crystallization, but with a slower crystallization rate. This work reveals a facile and scalable method that can be adopted to enhance the performance of lignin-based biocomposites.