Polypropylene Resin Research Articles

Mechanical Properties of Natural Composites: Hemp Fiber and Polypropylene Resin

Mechanical Properties of Natural Composites: Hemp Fiber and Polypropylene Resin

Laser-assisted thermoplastic composite automated fiber placement robot for bonding GF/PP unidirectional composites and braided composites

Laser-assisted thermoplastic composite automated placement method has been applied to the molding of composites due to its advantages of fast molding speed and high heating efficiency. This study focuses on designing a robot for laser-assisted thermoplastic composite automated fiber placement, employing a modular approach to create a versatile fiber placement head. Control functions, such as electrical circuits, a computer interface, and tension control, were developed. Hybrid laminates, combining GF/PP unidirectional and braided composites, were manufactured by independently adjusting laser power (275 W–400 W) and compression force (150 N–400 N). Bonding properties were analyzed using wedge peel tests and microscopic detection, revealing superior toughness in laser-assisted laminates compared to autoclave counterparts. Altering laser power and compression force impacted polypropylene resin distribution, influencing hybrid interlayer peel strength. The inclusion of braided materials and elevated mold temperature proved effective in minimizing lamination warpage in GF/PP laminates.

Oil-Loaded Mesoporous Silica to Enhance the Lubrication of Polypropylene Resin Composite Materials

Polymer self-lubricating materials have advantages such as low friction coefficient, good wear resistance, and high work efficiency, giving them wide application potential in friction and wear. This work fabricated polymer-based self-lubricating materials by incorporating oil-loaded mesoporous silica nanoparticles (MSNs + YR1800) in the polypropylene resin (PP). The effects of different content of MSNs + YR1800 on the tribological and mechanical properties of the obtained self-lubricating composite materials were studied. The results indicate that the content of MSNs + YR1800 in composite materials significantly impacts their tribological properties. When the content of MSNs + YR1800 was 10 wt%, the coefficient of friction reduced to 0.09,which was 84.5% lower than for PP and 78.6% lower than for composite materials containing 5 wt% mesoporous silica nanoparticle (MSNs). Compared with pure PP, the wear rate decreases from 4.93 × 10−11 m3∙Nm−1 to 4.43 × 10−13 m3∙Nm−1, which is reduced by two orders of magnitude. The excellent tribological properties of composite materials are attributed to the high specific surface area, large pore volume, strong adsorption capacity, and high oil loading capacity of mesoporous silica nanoparticle as nanofillers. The MSNs + YR1800 release lubricants to form a lubricating oil film during the friction process under load conditions, preventing direct contact between the friction pair and the surface of the composite material. Compared with polymer-silica hybrid oil-loaded microcapsules, MSNs + YR1800 can effectively reduce lubricant leakage, prolong operation life, improve lubrication efficiency, and ensure the continuous and stable existence of lubricating oil films.

Recovery of an Antioxidant Derived from a Phenolic Diphosphite from Wastewater during the Production of a Polypropylene Compound: A Step towards Sustainable Management.

Organic phosphoester (OPE) antioxidants are currently required due to their contribution to enhancing the quality of polymers, including polypropylene (PP). In this research, an integral methodology is presented for the efficient extraction of bis(2,4-dicumylphenyl) pentaerythritol diphosphite from industrial wastewater. Upon employing the solid-phase extraction (SPE) technique, the recovered compound is subjected to a comprehensive analysis of the recovered compound using high-performance liquid chromatography (HPLC), mass spectrometry (MS), thermal analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Subsequently, purified Bis(2,4-dicumylphenyl) pentaerythritol diphosphite was evaluated as a thermo-oxidative stabilizer after incorporation into PP resins. The relative standard deviation (RSD), Error (Er), linearity (R2), and percentage (%) recovery were less than 2.6, 2.5, more significant than 0.9995, and greater than 96%, respectively, for the inter-day and intra-day tests of the chromatographic method and the SPE. Except for chloroform, which was necessary due to the solubility properties of the investigated analyte, the use of environmentally friendly solvents, such as methanol and acetonitrile, was considered during the development of this research. The OPE extracted from industrial wastewater was characterized by FTIR, UV-Vis, DSC, TGA, and MS, allowing the elucidation of the structure of Bis(2,4-dicumylphenyl) pentaerythritol diphosphite (BDPD). The recovered OPE was mixed with PP resins, allowing it to improve its thermal properties and minimize its thermo-oxidative degradation. Organophosphorus flame retardant (OPE)' concentration in wastewater is alarming, ranging from 1179.0 to 4709.6 mg L-1. These exceed toxicity thresholds for aquatic organisms, emphasizing global environmental risks. Using a validated solid-phase extraction (SPE) technique with over 94% recovery, the study addresses concerns by removing organic contaminants and supporting circular economy principles. The high economic and environmental significance of recovering BDPD underscores the need for urgent global attention and intervention.

Distribution characteristics and microbial synergistic degradation potential of polyethylene and polypropylene in freshwater estuarine sediments

The microbial degradation of polyethylene (PE) and polypropylene (PP) resins in rivers and lakes has emerged as a crucial issue in the management of microplastics. This study revealed that as the flow rate decreased longitudinally, ammonia nitrogen (NH4+-N), heavy fraction of organic carbon (HFOC), and small-size microplastics (< 1 mm) gradually accumulated in the deep and downstream estuarine sediments. Based on their surface morphology and carbonyl index, these sediments were identified as the potential hot zone for PE/PP degradation. Within the identified hot zone, concentrations of PE/PP-degrading genes, enzymes, and bacteria were significantly elevated compared to other zones, exhibiting strong intercorrelations. Analysis of niche differences revealed that the accumulation of NH4+-N and HFOC in the hot zone facilitated the synergistic coexistence of key bacteria responsible for PE/PP degradation within biofilms. The findings of this study offer a novel insight and comprehensive understanding of the distribution characteristics and synergistic degradation potential of PE/PP in natural freshwater environments.

Hierarchical interface design of jute fibers/polypropylene composites for enhanced interfacial and mechanical properties

Natural fiber reinforced plastics (NFRPs) represent a promising category of emerging materials for sustainable industrial development owing to their renewability, degradability, and lightweight. However, the polarity mismatch between the fibers and polymer matrices weakens the mechanical properties of NFRPs. To address this issue, a novel hierarchical interface design was proposed here through the co-modification of silane coupling agents (SCAs) and zinc oxide nanorods (ZnO NRs), which exhibits not only high efficiency but also low energy consumption and environmental friendliness. Specifically, the hierarchical interface design was demonstrated on jute fibers (JFs)/polypropylene (PP) composites, where the JFs/ZnO interfaces were chemically bonded through complexation, chelation, or coordination using various SCAs; meanwhile, the ZnO/PP interfaces were physically bonded by interlocking effect. The experimental testing results indicated the exceptional mechanical properties of modified JFs and their composites. The JFs modified with 3-glycidyloxypropyltrimethoxysilane (KH560) and ZnO NRs exhibited an increase of 34.3% and 55.8% in single-fiber tensile strength and tensile modulus, respectively, compared to sololy ZnO coated JFs, and also showed an augment of 30.8% in the interfacial shear strength with PP resin. Thus, the transverse and longitudinal tensile strength of JFs/PP composites with combined modification of KH560 and ZnO NRs were 19.2% and 46.5% higher than untreated ones. The interfacial enhancement mechanism was ascribed to the synergistic effect of chemical bonding and physical interlocking, as revealed by molecular dynamics simulation and observation of fracture morphologies. The findings offer a cost-effective solution for developing JFs/PP composites with superior interfacial and mechanical properties, thereby promoting the practical applications and value of NFRPs.

MECHANICAL PROPERTIES OF CNTS INTEGRATED PP/GLASS FIBER REINFORCED BIAXIAL WEFT-KNITTED THERMOPLASTIC COMPOSITES WITH DIFFERENT KNITTING STRUCTURES

In this study, four types of biaxial weft-knitted (BWK) fabrics (polypropylene (PP) resin yarn/glass fiber (GF) with different knitting structures such as plain (P), interlock (INT), tuck (T) and tuck&amp;miss (TM) and multi-walled carbon nanotubes (MWCNTs) (0.4 wt%) were used as reinforcements to produce thermoplastic laminates with MWCNTs. In order to study the mechanical characteristics of the laminates, the flexural, short beam and Charpy impact tests on the samples were performed. In preliminary studies, the BWK fabrics with the plain knittings were used to produce the thermoplastic laminates with and without MWCNTs and positive effect of MWCNTs on the laminates were found out by performing the flexural tests on the specimens. The BWK laminates with the INT and TM knitting types with 0.4 wt% MWCNTs had almost same bending modulus and strength. 5% and 41% higher bending modulus and strength were gained with the BWK laminates with the interlock knitting type with 0.4-wt% MWCNTs compared to that was with the tuck type. 28.2% higher short beam strength and 57% higher Charpy impact energy were obtained with tuck&amp;miss with 0.4-wt% MWCNTs (21.02 MPa and 6.34 Joule) compared to that was with the tuck knitting (16.39 MPa and 4.04 Joule).

Enhancement of interfacial performance of carbon fiber reinforced polypropylene composites by dual action of polyetherimide nanoparticles and coatings

In order to enhance the interfacial bonding between carbon fibers (CFs) and polypropylene (PP) resin, a multiscale modification system of composite interfacial physical embedding-chemical bonding was established by the dual action of polyetherimide (PEI) nanoparticles and coatings prepared on the surface of CFs. Hemispherical PEI nanoparticles were prepared by evaporation-induced treatment to improve the mechanical interlocking ability of the composite interface. Based on PEI nanoparticles, coatings with different concentrations were introduced on the CF surface to exert chemical bonds and enhance compatibility with the PP resin. The surface properties of CFs, including chemical composition, morphology, wettability, and interfacial adhesion were systematically investigated. Compared with unmodified CFs, modified CFs showed increased surface roughness, enhanced surface activity, and improved surface wettability. Due to the dual action of PEI nanoparticles and coatings, the tensile strength and interlaminar shear strength (ILSS) of the composite were both enhanced. Specifically, the ILSS of PCF-0.10/PP composite increased by 119.35%, indicating that the dual modification significantly improved the mechanical reinforcement and interfacial adhesion of the composite. On this basis, the interfacial strengthening mechanism in the composite was proposed, and an effective and feasible method was proposed to improve the interfacial performance of composites. The method has the limitation of a long preparation time, but it is simple, easy, and cost-effective, which provides a promising prospect for the application of composites.

Effect of the Chemical Properties of Silane Coupling Agents on Interfacial Bonding Strength with Thermoplastics in the Resizing of Recycled Carbon Fibers

Upcycling recycled carbon fibers recovered from waste carbon composites can reduce the price of carbon fibers while improving disposal-related environmental problems. This study assessed and characterized recycled carbon fibers subjected to sizing treatment using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (APS) chemically coordinated with polyamide 6 (PA6) and polypropylene (PP) resins. Sizing treatment with 1 wt.% APS for 10 s yielded O=C-O on the surface of the carbon fiber, and the -SiOH in the APS underwent a dehydration–condensation reaction that converted O=C-O (lactone groups) into bonds of C-O (hydroxyl groups) and C=O (carbonyl groups). The effects of C-O and C=O on the interfacial bonding force increased to a maximum, resulting in an oxygen-to-carbon ratio (O/C) of 0.26. The polar/surface energy ratio showed the highest value of 32.29% at 10 s, and the interfacial bonding force showed the maximum value of 32 MPa at 10 s, which is about 15% better than that of commercial carbon fiber (PA6-based condition). In 10 s resizing treatments with 0.5 wt.% 3-methacryloxypropyltrimethoxysilane (MPS), C-O, C=O, and O=C-O underwent a dehydration–condensation reaction with -SiOH, which broke the bonds between carbon and oxygen and introduced a methacrylate group (H2C=C(CH3)CO2H), resulting in a significant increase in C-O and C=O, with an O/C of 0.51. The polar/surface free energy ratio was about 38% at 10 s, with the interfacial bonding force increasing to 27% compared to commercial carbon fiber (PP-based conditions). MPS exhibited a superior interfacial shear strength improvement, two times higher than that of APS, with excellent coordination with PP resin and commercial carbon fiber, although the interfacial bonding strength of the PP resin was significantly lower.

Effect of molecular weight distribution on the structure and properties of polypropylene cast film and stretched microporous membrane

Abstract Two isotactic polypropylene (iPP) resins with approximate weight-average molecular weight (Mw) and different molecular weight distribution (MWD) were chosen to prepare cast films by the melt-stretching method. The lamellar morphology and mechanical properties of the initial precursor films and stretched microporous membranes were characterized. It was found that PP1 resin with a broader MWD exhibits a higher relaxation time of around 5.5 s, a larger entanglement density of 24.7 mol/m3 and fast crystalline ability. The lamellar lateral size, orientation degree and entanglement density of the corresponding cast film are significantly increasing, resulting in higher elastic recovery and more apparent strain-hardening behavior. The PP resin with broader MWD also benefits the pore formation, resulting in a larger pore size and better air permeability of the stretched microporous membrane.

High frequency radar transmittance in bumper and exterior trim parts molded from thermoplastic olefins (TPOs): Part I TPO base resin

AbstractAn extensive investigation of the interaction of thermoplastic olefin (TPO) compounds with high frequency radar wave has been conducted to understand how TPO materials affect radar sensor efficiency, an important function for vehicle safety and especially the advancement of autonomous vehicles. In this article, the effect of major ingredients of a TPO on its dielectric properties was studied, and then a wide range of TPO compounds were evaluated for their radar transmittance or attenuation. It was demonstrated that the characteristics of polypropylene (PP) resin and rubber have little impact on the dielectric properties of a TPO, thus minimal influence on TPO's radar transparency, while increasing the talc loading in the compound increases the dielectric constant of the TPO. The TPO materials containing talc from 7% up to 34% were found to have dielectric constants ranging from 2.30 to 2.70 and nearly zero dielectric loss. Experiments confirmed that parts molded with these materials are transparent to high frequency radar wave at optimized thicknesses. Some pigments for coloring the materials also affect dielectric properties of TPOs, thus radar transmittance, with metal pigments showing the most impact. Finally, commercial TPO products are shown to have great batch to batch consistency in radar transmittance at a selected part thickness.

Chain microstructure of two in-reactor alloy impact polypropylene resins with same stiffness and different toughness

Chain microstructure of two in-reactor alloy impact polypropylene resins with same stiffness and different toughness

Suitability of MRF Recovered Post-Consumer Polypropylene Applications in Extrusion Blow Molded Bottle Food Packaging.

Polypropylene (PP) is one of the most abundant plastics used due to its low price, moldability, temperature and chemical resistance, and outstanding mechanical properties. Consequently, waste from plastic materials is anticipated to rapidly increase with continually increasing demand. When addressing the global problem of solid waste generation, post-consumer recycled materials are encouraged for use in new consumer and industrial products. As a result, the demand is projected to grow in the next several years. In this study, material recovery facility (MRF)-recovered post-consumer PP was utilized to determine its suitability for extrusion blow molded bottle food packaging. PP was sorted and removed from mixed-polymer MRF-recovered bales, ground, trommel-washed, then washed following the Association of Plastics Recyclers' protocols. The washed PCR-PP flake was pelletized then manually blended with virgin PP resin at 25%, 50%, 75, and 100% PCR-PP concentrations and fed into the extrusion blow molding (EBM) machine. The EBM bottles were then tested for physical performance and regulatory compliance (limits of TPCH: 100 μg/g). The results showed an increased crystallization temperature but no practical difference in crystallinity as a function of PCR-PP concentrations. Barrier properties (oxygen and water vapor) remained relatively constant except for 100% MRF-recovered PCR-PP, which was higher for both gas types. Stiffness significantly improved in bottles with PCR-PP (p-value < 0.05). In addition, a wider range of N/IAS was detected in PCR-PP due to plastic additives, food additives, and degradation byproducts. Lastly, targeted phthalates did not exceed the limits of TPCH, and trace levels of BPA were detected in the MRF PCR-PP. Furthermore, the study's results provide critical information on the use of MRF recovered in food packaging applications without compromising performance integrity.

Chain microstructure comparison of two transparent polypropylene resins fractionated by temperature rising elution fractionation

Chain microstructure comparison of two transparent polypropylene resins fractionated by temperature rising elution fractionation

Analysis of GMT Composite Material-based Building Formwork

GMT (Glass Mat Reinforced Thermoplastics) is a new type of composite material made of mica and glass fiber blended into a polypropylene resin substrate, and it is durable, lightweight, high-strength, translucent and easy to install, what’s more, it can be recycled and reused to meet the needs of energy conservation and environmental protection. It is one of the mainstream building formwork materials at present. This paper analyzes and summarizes the performance of the new formwork of GMT, compares it with the traditional mainstream template, studies the problems existing in the development of GMT formwork and conducts corresponding analysis. It is pointed out that through continuous improvement of GMT formwork construction technology and the entire formwork system, its technical advantages can be fully utilized and maintained, in order to provide reference for the further development of GMT new building formwork.

Effect of Ethylene Comonomer Content on the Foam Processing Window of Long-Chain Branched Polypropylene

The non-optimized foam processing window (FPW) can create processing challenges and limit the possible materials with which a polymer of interest can be processed in emerging foaming technologies. To address this drawback, we aim to investigate the effect of ethylene comonomer content on the foaming behavior of polypropylene (PP), particularly the FPW. Two PP resins containing 0.75 and 1.5 wt % of ethylene comonomers were studied, while using a PP homopolymer as a control. High-pressure differential scanning calorimetry confirmed the decrease in the onset crystallization (Tc-onset) and end melting (Tm-end) temperatures with increasing ethylene comonomer content as a result of the defects the ethylene units induce in the crystalline structure of PP. Rheological measurements suggest that the addition of ethylene comonomer content resulted in negligible changes in the extensional and shear rheological responses of the PP-based resins. In addition, the foam expansion results and the observed morphologies reveal no significant change in the resins’ foamability, characterized by the shape of their expansion profiles with respect to the foaming temperature. Interestingly, the FPW was found to be the sole affected parameter, as 1.5 wt % of ethylene comonomers resulted in a 10 °C shift in the FPW toward lower temperatures, compared to the PP homopolymer. The resins with 0 and 1.5 wt % of ethylene comonomer content showed similar mechanical responses under compression tests for their optimally expanded samples. These findings reveal a potentially effective approach for tuning the FPW of processed PP resins without compromising their foaming and mechanical performances. Consequently, foam processing techniques are further enhanced, resulting in a wider span of potential applications.

Synthesis of silylamine and siloxyamine compounds: A novel approach to flame retardancy of polypropylene and Epoxy resins

A series of innovative flame retardants containing N-Si and N-O-Si bonds have been synthesized. Their chemical structures were verified by nuclear magnetic resonance (NMR) spectroscopy and thermal stabilities determined by thermogravimetric analysis (TGA). The results indicate that their thermal and hydrolytic stabilities could be adjusted by fine tuning their silylamine (N-Si) and siloxyamine (N-O-Si) skeletons. Thus, the substituents bonded to the phthalimides, such as diphenylmethylsilyl, dimethylphenylsilyl, diphenyl‑tert-butylsilyl, triisopropylsilyl or diphenylmethylsiloxy; whichever was attached to the imide played a significant role on its thermal and hydrolytic properties. Upon thermal dissociation, the N-Si and N-O-Si compounds were shown to yield aminyl, silyl and oxygen-centered radicals that provided fire proofing effect in polypropylene (PP) films alone and a synergistic effect in combination with conventional phosphorous flame retardant in PP, linear low-density polyethylene (LLDPE) and epoxy resins (EP). Their efficacy as flame retardants alone in thin PP films were evaluated according to the DIN4102-B2 test. Both N-Si and N-O-Si significantly slowed down the burning of PP films. Moreover, their potential as adjuvants with a conventional phosphorous based flame retardant, i.e., spirocyclic phosphonate (AFLAMMIT® PCO 900) in PP and EP resins was evaluated according to the UL-94 V fire standard. A synergistic effect was observed when the phosphorous flame retardant was combined with either N-Si or N-O-SI containing compounds, since none of the flame retardants by themselves could provide V-0 rating in the UL94-V test in PP, LLDPE or EP resins even at much higher loadings. The thermogravimetric analysis carried out under inert atmosphere revealed enhanced and earlier onset of decomposition and thermal activation of phosphorous based flame retardant in the presence of N-Si or N-O-Si in comparison to spirocyclic phosphonate, N-Si or N-O-Si used alone, respectively. The interaction of the phosphorus flame retardant with N-Si was verified by 31P NMR.

Polyplastics targets PLASTRON® long cellulose fiber reinforced resin for automotive applications

On March 24, 2023, Polyplastics Group announced that its newly developed long cellulose fiber reinforced polypropylene (PP) resin, PLASTRON® LFT, is being targeted for automotive applications such as door module carriers, center consoles, and armrest cores. PLASTRON® LFT reportedly offers lower density and reduced greenhouse gas (GHG) emissions than short glass-reinforced resins while delivering the same mechanical properties.

Extraction and Estimation of antistatic agent Glycerol Mono Stearate in Polypropylene by Gas Chromatography Coupled with Flame Ionisation Detector

A new method has been developed for the estimation of an antistatic agent Glycerol Mono Stearate (GMS) in Polypropylene (PP) over Gas Chromatography coupled with Flame ionization detector (GC-FID). In the present work, selection of suitable sample specimen, sample weight, solvent mixture, extraction time, and temperature have been identified for the extraction of GMS in the PP resin. In-house Polypropylene pellet has been used for study and the GMS extorted into n-hexane-Ethyl acetate and quantified using GC-FID over 100% Dimethylpolysiloxane column. The method limit of detection is 1 mg/L and the limit of quantification is 5-750 mg/kg in PP resin with a correlation coefficient greater than 0.999. This method is accurate and has not found any interference with other co additives used in the propylene.

Kendrick mass defect analysis-based data mining technique for trace components in polyolefins observed by pyrolysis-gas chromatography/high-resolution mass spectrometry

Pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) is utilized as an effective technique to characterize additives and degradation products of polyolefins. However, non-target analysis of trace components buried in complex chromatograms or mass spectra is a difficult task without prior information on sample composition. In this report, we propose a data mining method that extracts meaningful trace components by combining Py-GC/time-of-flight MS (Py-GC/TOFMS) and Kendrick mass defect (KMD) analysis. In our first demonstration, we characterized the additives in the polyethylene (PE) cap of a polyethylene terephthalate (PET) beverage bottle using Py-GC/TOFMS. The summed mass spectrum, built by summing all the mass spectra over the entire range of the pyrogram, was converted to a two-dimensional KMD plot. Specific dots on the KMD plot at a distance from the dots relating to a series of hydrocarbon-derived fragment ions suggested the presence of additives. The types of additives could be identified by a library search for the extracted ion chromatograms (EICs) derived from the corresponding mass of the specific dots. The second demonstration was related to the detection of oxidized products in polypropylene (PP) resin. A “Remainders of KM” (RKM) plot was able to highlight the presence of a series of fragment ions of trace PP pyrolysates with one and two oxygen atoms. Relative peak intensities of the ions containing oxygen atoms were useful as an oxidation index to evaluate the degree of degradation in the very early stages of degradation.