EXPRESS: Simultaneous Measurement of Two-Trace Two-Dimensional (2T2D) Near-Infrared (NIR) Asynchronous Correlation Spectra and Small Angle X-ray Scattering (SAXS) to Characterize Thermally Aged Polypropylene (PP).

In this study, a new system was developed to carry out simultaneous near-infrared (NIR) and small-angle X-ray scattering (SAXS) measurements. Aged PP was examined with the NIR-SAXS system to demonstrate how it can be utilized to derive pertinent information about polymer structure. Pairs of SAXS profiles and NIR spectra of PP in its initial state and after aging were measured to derive an in-depth understanding of the aging phenomenon. The SAXS profiles of the PP samples showed a clear shift of the SAXS peak to the lower q direction induced by the thermal aging, indicating an increase in the length of the long-period structure. Two-trace two-dimensional (2T2D) asynchronous correlation spectra derived from NIR spectra clearly revealed that the aging treatment leads to the substantial increase in the spectral intensity of the regularity bands representing the longer helix present in a folded lamellar structure. In other words, it suggest that the long helix structure is more abundantly present than the short helix structure in the aged PP than in the initial PP. By combining the information derived from the SAXS profiles and NIR spectra, the details of the aging-induced variation were clearly determined. Namely, aging causes additional crystallization of the PP by developing more helix structures, which involves an increase in lamellar thickness as well as a decrease in the amorphous region. The growth of the rigid crystalline phase restricts the elastic deformation in the amorphous structure, which eventually induces the deterioration of PP by making the polymer hard but brittle. Such observation, in turn, implies that the retarding or accelerating the crystallized structure of PP substantially works to control the progress of the aging.

Pyrolytic Depolymerization of Polyolefins Catalyzed by Zirconium-based UiO-66 Metal-Organic Frameworks.

Polyolefins such as polyethylenes and polypropylenes are the most-produced plastic waste globally, yet are difficult to convert into useful products due to their unreactivity. Pyrolysis is a practical method for large-scale treatment of mixed, contaminated plastic, allowing for their conversion into industrially-relevant petrochemicals. Metal-organic frameworks (MOFs), despite their tremendous utility in heterogenous catalysis, have been overlooked for polyolefin depolymerization due to their perceived thermal instabilities and inability of polyethylenes and polypropylenes to penetrate their pores. Herein, we demonstrate the viability of UiO-66 MOFs containing coordinatively-unsaturated zirconia nodes, as effective catalysts for pyrolysis that significantly enhances the yields of valuable liquid and gas hydrocarbons, whilst halving the amounts of residual solids produced. Reactions occur on the Lewis-acidic UiO-66 zirconia nodes, without the need for noble metals, and yields aliphatic product distributions distinctly different from the aromatic-rich hydrocarbons from zeolite catalysis. We also demonstrate the first unambiguous characterization of polyolefin penetration into UiO-66 pores at pyrolytic temperatures, allowing access to the abundant Zr-oxo nodes within the MOF interior for efficient C-C cleavage. Our work highlights the potential of MOFs as highly-designable heterogeneous catalysts for depolymerization of plastics which can complement conventional catalysts in reactivity.

Chitosan-based biopolyelectrolyte complexes intercalated montmorillonite: A strategy for green flame retardant and mechanical reinforcement of polypropylene composites.

Due to dwindling petroleum resources and the need for environmental protection, the development of bio-based flame retardants has received much attention. In order to explore the feasibility of fully biomass polyelectrolyte complexes (PEC) for polyolefin flame retardant applications, chitosan (CS), sodium alginate (SA), and sodium phytate (SP) were used to prepare CS-based fully biomass PEC intercalated montmorillonite (MMT) hybrid biomaterials (SA-CS@MMT and SP-CS@MMT). The effects of two hybrid biomaterials on the fire safety and mechanical properties of intumescent flame-retardant polypropylene (PP) composites were compared. The SP-CS@MMT showed the best flame retardancy and toughening effect at the same addition amount. After adding 5 wt% SP-CS@MMT, the limiting oxygen index (LOI) value of PP5 reached 30.9 %, and the peak heat release rate (pHRR) decreased from 1348 kW/m2 to 163 kW/m2. In addition, the hydrogen bonding between polyelectrolyte complexes significantly improved the mechanical properties of PP composites. Compared with PP2, the tensile strength of PP5 increased by 59 %. This study provided an efficient and eco-friendly strategy for the large-scale production of renewable biomaterials with good thermal stability and expanded the application of macromolecular biomaterials in the field of fire safety.

Diet composition and plastic ingestion in Poecilia reticulata from urban streams.

Fish are excellent bioindicators and can reveal the presence of plastic in the environment. Diagnosing the composition and abundance of polymers in the fish diet makes it possible to evaluate their point sources and possible trophic transfers. We aimed to use the gastrointestinal contents of Poecilia reticulata in subtropical urban streams to detect the occurrence, shape, color, size, and chemical composition of polymers. For this, the diet of 240 individuals was analyzed using the volumetric method, and the microplastics (MPs; < 5 mm) recorded were characterized using Raman spectroscopy. Individuals predominantly consumed organic detritus and aquatic macroinvertebrates, with higher proportions of Diptera. A total of 111 plastic particles (< 0.5 to 12 mm) were recorded, and a subset of 14.4% was subjected to a micro-Raman spectrometer (830 nm excitation). The occurrence of polyethylene terephthalate (PET) and polypropylene (PP) with phthalocyanine dye was recorded. Some fragments could not be identified by Raman, but they contained indigo blue dye. Poecilia reticulata had a predominantly detritivorous diet with a record of plastic consumption, reflecting environmental pollution. Our results demonstrate that individuals of P. reticulata have ingested MPs in urban streams. This reinforces the need for future studies on the relationship between the presence of MPs in fish and the level of pollution in streams, comparisons with species of different feeding habits, and the potentially harmful effects on the entire biota.

Functionalization of Polypropylene by TiO2 Photocatalytic Nanoparticles: On the Importance of the Surface Oxygen Plasma Treatment.

A new two-step method for developing a nanocomposite of polypropylene (PP) decorated with photocatalytically active TiO2 nanoparticles (nTiO2) is proposed. This method involves the low-temperature plasma functionalization of polypropylene followed by the ultrasound-assisted anchoring of nTiO2. The nanoparticles, polymeric substrate, and resultant nanocomposite were thoroughly characterized using nanoparticle tracking analysis (NTA), microscopic observations (SEM, TEM, and EDX), spectroscopic investigations (XPS and FTIR), thermogravimetric analysis (TG/DTA), and water contact angle (WCA) measurements. The photocatalytic activity of the nanocomposites was evaluated through the degradation of methyl orange. The individual TiO2 nanoparticles ranged from 2 to 6 nm in size. The oxygen plasma treatment of PP generated surface functional groups (mainly -OH and -C=O), transforming the surface from hydrophobic to hydrophilic, which facilitated the efficient deposition of nTiO2. Optimized plasma treatment and sonochemical deposition parameters resulted in an active photocatalytic nTiO2/PP system, degrading 80% of the methyl orange under UVA irradiation in 200 min. The proposed approach is considered versatile for the functionalization of polymeric materials with photoactive nanoparticles and, in a broader perspective, can be utilized for the fabrication of self-cleaning surfaces.

The Effects of Polypropylene Microplastics on the Removal of Nitrogen and Phosphorus from Water by Acorus calamus, Iris tectorum and Functional Microorganisms.

Polypropylene microplastics (PP-MPs), an emerging pollutant, adversely affect the ability of aquatic plants to restore water bodies, thereby compromising the functionality and integrity of wetland ecosystems. This study examines the effects of microplastic stress on the nitrogen and phosphorus removal capacities of Acorus calamus and Iris tectorum, as well as on functional microorganisms within the aquatic system. The findings indicate that under PP-MP stress, the nitrogen and phosphorus absorption capabilities of both plants were diminished. Additionally, there was a significant reduction in the metabolic enzyme activities related to nitrogen and phosphorus in the plants, alongside a notable decrease in leaf nitrogen content. PP-MPs hinder the nutrient uptake of plants, affecting their growth and indirectly reducing their ability to utilize nitrogen and phosphorus. Specifically, in the 10 mg·L-1 treatment group, A. calamus and I. tectorum showed reductions in leaf nitrogen content by 23.1% and 31.0%, respectively, and by 14.8% and 27.7% in the 200 mg·L-1 treatment group. Furthermore, I. tectorum had higher leaf nitrogen levels than A. calamus. Using fluorescent tagging, the distribution of PP-MPs was traced in the roots, stems, and leaves of the plants, revealing significant growth impairment in both species. This included a considerable decline in photosynthetic pigment synthesis, enhanced oxidative stress responses, and increased lipid peroxidation in cell membranes. PP-MP exposure also significantly reduced the abundance of functional microorganisms involved in denitrification and phosphorus removal at the genus level in aquatic systems. Ecological function predictions revealed a notable decrease in nitrogen cycling functions such as nitrogen respiration and nitrite denitrification among water microorganisms in both treatment groups, with a higher ecological risk potential in the A. calamus treatment group. This study provides new insights into the potential stress mechanisms of PP-MPs on aquatic plants involved in water body remediation and their impacts on wetland ecosystems.

Identification and quantification of micro-nano-plastics in polypropylene-bottled injections.

Micro-nano-plastic (MNP) particles (p) in the environment can enter the human body and pose a potential threat to human health. However, it is unknown whether these substances are present in polypropylene (PP) plastic-bottled injections, which are used as high-frequency intravenous infusions to treat diseases. Therefore, the objective of this study was to identify and quantify insoluble MNP particles in 16 batches of injectable formulations within the validity period. Primarily, ethylene-propylene copolymer or P(E-P) micro-plastic (MP) particles (2-10 µm, 216 p/mL) were identified by micro-Raman spectroscopy, and nano-particles (<50 nm, 2.1 × 104 p/mL) similar to PP containing only carbon were detected by scanning electron microscopy-energy-dispersive X-ray spectroscopy (photoelectron). Furthermore, P(E-P) MP particles (1 × 103 to 1 × 105 ng/L) from the injections were enriched on the GF-B filter, and PP or P(E-P) nano-plastic (NP) particles (1 × 103 to 4 × 104 ng/L) enriched on the alumina film were detected by pyrolysis-gas chromatography/mass spectrometry. Finally, the total insoluble particles in injections were 6 × 104 to 1 × 107 p/mL (0.02-100 µm). Our findings are the first to identify and quantify MNPs in PP-bottled injections. Considering that they can enter the blood circulation, so whether cause disease remains to be investigated.

Eco-toxicity assessment of polypropylene microplastics in juvenile zebrafish (Danio rerio).

In recent years, everyone has recognized microplastics as an emerging contaminant in aquatic ecosystems. Polypropylene is one of the dominant pollutants. The purpose of this study was to examine the effects of exposing zebrafish (Danio rerio) to water with various concentrations of polypropylene microplastics (11.86 ± 44.62 µm), including control (0 mg/L), group 1 (1 mg/L), group 2 (10 mg/L), and group 3 (100 mg/L) for up to 28 days (chronic exposure). The bioaccumulation of microplastics in the tract was noted after 28 days. From the experimental groups, blood and detoxifying organs of the liver and brain were collected. Using liver tissues evaluated the toxic effects by crucial biomarkers such as reactive oxygen species, anti-oxidant parameters, oxidative effects in protein & lipids, total protein content and free amino acid level. The study revealed that the bioaccumulation of microplastics in the organisms is a reflection of the oxidative stress and liver tissue damage experienced by the group exposed to microplastics. Also, apoptosis of blood cells was observed in the treated group as well as increased the neurotransmitter enzyme acetylcholine esterase activity based on exposure concentration-dependent manner. The overall results indicated bioaccumulation of microplastics in the gut, which led to increased ROS levels. This consequently affected antioxidant biomarkers, ultimately causing oxidation of biomolecules and liver tissue injury, as evidenced by histological analysis. This study concludes that chronic ingestion of microplastics causes considerable effects on population fitness in the aquatic environment, as well as other ecological complications, and is also critical to understand the magnitude of these contaminants' influence on ichthyofauna.

Machine learning prediction of the mechanical properties of injection-molded polypropylene through X-ray diffraction analysis.

Predicting the mechanical properties of polymer materials using machine learning is essential for the design of next-generation of polymers. However, the strong relationship between the higher-order structure of polymers and their mechanical properties hinders the mechanical property predictions based on their primary structures. To incorporate information on higher-order structures into the prediction model, X-ray diffraction (XRD) can be used. This study proposes a strategy to generate appropriate descriptors from the XRD analysis of the injection-molded polypropylene samples, which were prepared under almost the same injection molding conditions. To this end, first, Bayesian spectral deconvolution is used to automatically create high-dimensional descriptors. Second, informative descriptors are selected to achieve highly accurate predictions by implementing the black-box optimization method using Ising machine. This approach was applied to custom-built polymer datasets containing data on homo- polypropylene and derived composite polymers with the addition of elastomers. Results show that reasonable accuracy of predictions for seven mechanical properties can be achieved using only XRD.

This study proposes a strategy to generate appropriate descriptors, which realize highly accurate predictions of mechanical properties via machine learning from the XRD analysis of the molded polypropylene samples.

Antarctic wastewater: A local source of microplastic pollution.

Microplastic (MP) particles can be found all around the planet, even in Antarctica where they can be locally originated or transported by marine currents and winds. In this communication, we identify and report for the first time the contribution of a wastewater treatment plant (WWTP) as a local source of MP particles in the region. The analysis of the entire sample using micro-Raman spectroscopy revealed an MP concentration that ranged from 64 to 159 particles per liter of wastewater. >90 % of the identified particles were smaller than 50 µm. Among those analyzed, microplastics were identified as polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyethylene terephthalate, and polystyrene. These findings demonstrate the need for urgent policies and technologies to mitigate this MP contamination source.

Investigation of pulmonary inflammatory responses following intratracheal instillation of and inhalation exposure to polypropylene microplastics.

BACKGROUND: Microplastics have been detected in the atmosphere as well as in the ocean, and there is concern about their biological effects in the lungs. We conducted a short-term inhalation exposure and intratracheal instillation using rats to evaluate lung disorders related to microplastics. We conducted an inhalation exposure of polypropylene fine powder at a low concentration of 2 mg/m3 and a high concentration of 10 mg/m3 on 8-week-old male Fischer 344 rats for 6 h a day, 5 days a week for 4 weeks. We also conducted an intratracheal instillation of polypropylene at a low dose of 0.2 mg/rat and a high dose of 1.0 mg/rat on 12-week-old male Fischer 344 rats. Rats were dissected from 3 days to 6 months after both exposures, and bronchoalveolar lavage fluid (BALF) and lung tissue were collected to analyze lung inflammation and lung injury. RESULTS: Both exposures to polypropylene induced a persistent influx of inflammatory cells and expression of CINC-1, CINC-2, and MPO in BALF from 1 month after exposure. Genetic analysis showed a significant increase in inflammation-related factors for up to 6 months. The low concentration in the inhalation exposure of polypropylene also induced mild lung inflammation. CONCLUSION: These findings suggest that inhaled polypropylene, which is a microplastic, induces persistent lung inflammation and has the potential for lung disorder. Exposure to 2 mg/m3 induced inflammatory changes and was thought to be the Lowest Observed Adverse Effect Level (LOAEL) for acute effects of polypropylene. However, considering the concentration of microplastics in a real general environment, the risk of environmental hazards to humans may be low.

Evaluation of polypropylene CSF low-bind collection tubes for trace metal contamination.

BACKGROUND: Due to the ability of metal ions to cross the blood-brain barrier, there has been interest in analyzing cerebrospinal fluid (CSF) for trace element concentrations to investigate possible correlations with neurodegenerative diseases. In this study, Sarstedt polypropylene CSF collection tubes were analyzed to determine the contamination levels of aluminum, titanium, chromium, manganese, cobalt, nickel, molybdenum, gadolinium, vanadium, arsenic, cadmium, mercury, lead, thallium, selenium, copper, zinc, and iron. METHODS: Sarstedt polypropylene CSF collection tubes from 2 separate lots (n = 10 per lot) were filled with a 2 mL aliquot of a CSF pool with known element concentrations. After 24 hours of leaching at room temperature, all 18 elements were analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Results were subtracted from the initial pool concentration to determine contamination levels. RESULTS: No detectable contamination above the assay limit of detection was found in 11 analytes. Molybdenum and selenium contamination was measured in all tubes, and aluminum, titanium, manganese, thallium, and zinc had minimal levels of sporadic detectable contamination in 25% or fewer of the tubes tested. CONCLUSIONS: Sarstedt polypropylene CSF tubes are an acceptable collection tube for the analysis of most assessed metals in CSF.

Triaxiality and Plastic-Strain-Dependent Proposed PEAK Parameter for Predicting Crack Formation in Polypropylene Polymer Reservoir Subjected to Pressure Load.

This article raises the topic of the critical examination of polypropylene, a key polymeric material, and its extensive application within the automotive industry, particularly focusing on the manufacturing of brake fluid reservoirs. This study aims to enhance the understanding of polypropylene's behavior under mechanical stresses through a series of laboratory destruction tests and numerical simulations, emphasizing the finite element method (FEM). A novel aspect of this research is the introduction of the PEAK parameter, a groundbreaking approach designed to assess the material's resilience against varying states of strain, known as triaxiality. This parameter facilitates the identification of critical areas prone to crack initiation, thereby enabling the optimization of component design with a minimized safety margin, which is crucial for cost-effective production. The methodology involves conducting burst tests to locate crack initiation sites, followed by FEM simulations to determine the PEAK threshold value for the Sabic 83MF10 polypropylene material. The study successfully validates the predictive capability of the PEAK parameter, demonstrating a high correlation between simulated results and actual laboratory tests. This validation underscores the potential of the PEAK parameter as a predictive tool for enhancing the reliability and safety of polypropylene automotive components. The research presented in this article contributes significantly to the field of material science and engineering by providing a deeper insight into the mechanical behavior of polypropylene and introducing an effective tool for predicting crack initiation in automotive components. The findings hold promise for advancing the design and manufacturing processes in the automotive industry, with potential applications extending to other sectors.

Composites from Recycled Polypropylene and Carboxymethylcellulose with Potential Uses in the Interior Design of Vehicles.

This research investigates novel polymeric composite materials for automotive interior trim applications. The composites utilize recycled polypropylene (PPr) matrix and carboxymethylcellulose (CMC) as filler (PPr/CMC: 100/0, 95/5, and 90/10 wt.%). The materials were processed by extrusion and injection molding. Considering their intended application, the composites were evaluated for resistance to key climatic factors, i.e., temperature, humidity, and UV radiation. In addition, structural analyses and FTIR analyses were performed to assess potential heterogeneity and thermal stability. Following FTIR tests, the incorporation of carboxymethyl cellulose in polypropylene is confirmed by the detection of characteristic CMC bands for -OH, C=O, and C-O-C groups. The results indicate slight structural heterogeneity in the 5% and 10% CMC composites. However, no thermal distortions were observed in either the composites or the PPr matrix itself. The behavior of PPr/CMC composites under the action of the mentioned climatic factors has been assessed from the variation of dielectric characteristics with frequency. The strong polarization of CMC leads to a sharp increase in composites electrical conductivity after submersion in water for 480 h, suggesting weakening of the composite structure. After exposure to UV radiation, a sharp increase in conductivity is observed even after the first cycle (72 h) of UV radiation. Following the experimental results obtained in our study, it is recommended to use the PPr +10% CMC composite for obtaining different interior ornaments (carpets, supports, etc.). At the same time, the use of these materials also has the advantage of lightening the mass of the vehicle due to their lower density than polymers.

Fabric structure and polymer composition as key contributors to micro(nano)plastic contamination in face masks.

The surge in face mask use due to COVID-19 has raised concerns about micro(nano)plastics (MNPs) from masks. Herein, focusing on fabric structure and polymer composition, we investigated MNP generation characteristics, mechanisms, and potential risks of surgical polypropylene (PP) and fashionable polyurethane (PU) masks during their wearing and photoaging based on stereomicroscope, µ-Fourier transform infrared spectroscopy (µ-FTIR), and scanning electron microscope (SEM) techniques. Compared with new PP and PU masks (66 ± 16 MPs/PP-mask, 163 ± 83 MPs/PU-mask), single- and multiple-used masks exhibited remarkably increased MP type and abundance (600-1867 MPs/PP-mask, 607-2167 MPs/PU-mask). Disinfection exacerbated endogenous MP generation in masks, with washing (416 MPs/PP-mask, 30,708 MPs/PU-mask) being the most prominent compared to autoclaving (219 MPs/PP-mask, 553 MPs/PU-mask) and alcohol spray (162 MPs/PP-mask, 18,333 MPs/PU-mask). Photoaging led to massive generation of MPs (8.8 × 104-3.7 × 105 MPs/PP-layer, 1.0 × 105 MPs/PU-layer) and NPs (5.2 × 109-3.6 × 1013 NPs/PP-layer, 3.5 × 1012 NPs/PU-layer) from masks, presenting highly fabric structure-dependent aging modes as "fragmentation" for fine fiber-structure PP mask and "erosion" for 3D mesh-structure PU mask. The MNPs derived from PP/PU mask caused significant deformities of Zebrafish (Danio rerio) larvae. These findings underscore the potential adverse effects of masks on humans and aquatic organisms, advocating to enhance proper use and rational disposal for masks.

Multiple Traces of Families of Epoxy Derivatives as New Inhibitors of the Industrial Polymerization Reaction of Propylene.

In this study, the impact of ethylene oxide, propylene oxide, 1,2-butene oxide, and 1,2-pentene oxide on the polymerization of propylene at an industrial level was investigated, focusing on their influence on the catalytic efficiency and the properties of polypropylene (PP) without additives. The results show that concentrations between 0 and 1.24 ppm of these epoxides negatively affect the reaction's productivity, the PP's mechanical properties, the polymer's fluidity index, and the PP's thermal properties. Fourier transform infrared spectroscopy (FTIR) revealed bands for the Ti-O bond and the Cl-Ti-O-CH2 bonds at 430 to 475 cm-1 and 957 to 1037 cm-1, respectively, indicating the interaction between the epoxides and the Ziegler-Natta catalyst. The thermal degradation of PP in the presence of these epoxides showed a similar trend, varying in magnitude depending on the concentration of the inhibitor. Sample M7, with 0.021 ppm propylene oxide, exhibited significant mass loss at both 540 °C and 600 °C, suggesting that even small concentrations of this epoxide can markedly increase the thermal degradation of PP. This pattern is repeated in samples with 1,2-butene oxide and 1,2-pentene oxide. These results highlight the need to strictly control the presence of impurities in PP production to optimize both the final product's quality and the polymerization process's efficiency.

Elaborating more realistic model microplastics by simulating polypropylene's environmental ageing.

In this work, we propose a new protocol for producing model microplastics from an industrial polymer and compare it to a conventional method, cryomilling. Polypropylene industrial pellets were chosen due to their widespread production and frequent presence in the environment, making them a notable source of microplastics. Both protocols start with aging under Ultra-Violet light of the pellets but differ in the subsequent mechanical stress applied-strong vs. soft-to break down the photodegraded pellets into microplastics. All generated particles were fully characterized in terms of size, shape, oxidation rate, and stability in aqueous media. Microplastics produced via cryomilling exhibited significant size and oxidation heterogeneity and tended to aggregate in water. Although the new protocol involving soft mechanical stress required a longer preparation time, it simulated more accurately the environmental degradation of raw plastic. This method successfully produced oxidized microplastics with a controlled size distribution centered around 50 µm which remained stable in water without stabilizers.

Synthesis and Flame Retardant Behavior of Phosphorous- and Nitrogen-Containing Copolymer and Its Application in Polypropylene.

In this study, a 4-(hydroxymethyl)-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxide (PEPA)-functionalized acrylate monomer, PEPAA, is designed and utilized for the synthesis of macromolecular flame retardants poly(PEPAA-co-AM) with varying PEPAA/AM ratio through copolymerization with acrylamide (AM). The poly(PEPAA-co-AM) is then incorporated into polypropylene (PP) to prepare PP/poly(PEPAA-co-AM) composites. The flame retardant effect of poly(PEPAA-co-AM) on PP is investigated using cone calorimetric test (CCT), and compared with that of PEPAA homopolymer (P-PEPAA), AM homopolymer (PAM), and blends of P-PEPAA/PAM. The results demonstrate that, in comparison with P-PEPAA, PAM, and blends of P-PEPAA/PAM, the incorporation of poly(PEPAA-co-AM) significantly enhances the flame retardancy of PP. Notably, the best flame retardancy is achieved when the ratio of PEPAA/AM copolymerization in poly(PEPAA-co-AM) is 2/8. The morphology and composition of residual chars from combustion are analyzed using SEM-EDS while the residual graphitization degree is examined through Raman spectroscopy. Additionally, TG-FTIR-MS is utilized to investigate the pyrolysis products in gas phase during thermal decomposition of poly(PEPAA-co-AM). Based on these experimental results, a flame retardant mechanism for poly(PEPAA-co-AM) is proposed. The PP/poly(PEPAA-co-AM) composites not only retain the excellent processing properties of pure PP but also exhibit enhanced mechanical properties.

Properties of Fiber-Reinforced Geopolymer Mortar Using Coal Gangue and Aeolian Sand.

Geopolymers, as a novel cementitious material, exhibit typical brittle failure characteristics under stress. To mitigate this brittleness, fibers can be incorporated to enhance toughness. This study investigates the effects of varying polypropylene fiber (PPF) content and fiber length on the flowability, mechanical properties, and flexural toughness of coal gangue-based geopolymers. Microstructural changes and porosity variations within the Fiber-Reinforced Geopolymer Mortar(GMPF) matrix were observed using scanning electron microscope (SEM) and Low field NMR(LF-NMR) to elucidate the toughening mechanism of PPF-reinforced geopolymers. The introduction of fibers into the geopolymer matrix demonstrated an initial bridging effect in the viscous geopolymer slurry, with a 3.0 vol% fiber content reducing fluidity by 5.6%. Early mechanical properties of GMPF were enhanced with fiber addition; at 1.5 vol% fiber content and 15 mm length, the 3-day flexural and compressive strengths increased by 30.81% and 17.4%, respectively. Furthermore, polypropylene fibers significantly improved the matrix's flexural toughness, which showed an increasing trend with higher fiber content. At a 3.0 vol% fiber content, the flexural toughness index increased by 198.35%. The data indicated that a fiber length of 12 mm yielded the best toughening effect, with an 84.03% increase in the flexural toughness index. SEM observations revealed a strong interfacial bond between fibers and the matrix, with noticeable damage on the fiber surface due to frictional forces, and fiber pull-out being the predominant failure mode. Porosity testing results indicated that fiber incorporation substantially improved the internal pore structure of the matrix, reducing the median pore diameter of mesopores and converting mesopores to micropores. Additionally, the number of harmless and less harmful pores increased by 23.01%, while the number of more harmful pores decreased by 30.43%.

Experimental Study on Impact Performance of Basalt-Polypropylene Fiber Reinforced High-Performance Concrete.

To enhance the impact resistance of high-performance concrete (HPC), a novel efficient solution was adopted by incorporating basalt fibers (BF) and polypropylene fibers (PF) as reinforcement materials in this work. To this end, the effects of single BF (BHC) and PF (PHC) as well as their combinations (BPHPC) on the impact energy consumption, ductility ratio, and toughness factor were explored through drop weight impact test of concrete considering fiber volume contents (0.1%, 0.15%, 0.2%) to evaluate the impact resistance of the concrete. The Weibull distribution function model is used to fit the drop weight impact test results and predict the probability of failure. Moreover, the fracture-resistance enhancement mechanism of fiber is analyzed at a microscopic level. Test results showed that the number of impacts resisted by the HPC can follow well the two-parameter Weibull distribution. Compared with the single BF and single PF, the combination of 0.15% BF and 0.1% PF yields favorable impact resistance, thus exhibiting a positive hybrid effect.