Performance Of Polypropylene Research Articles

Relationship between Xylene Solubles and Crystallization Elution Fractionation of Polypropylene.

The Xylene Soluble (XS) is one of the most important parameters closely related to the performance of polypropylene (PP) materials. In order to obtain precise and accurate XS data, ASTM D 5492-17, based on the wet chemistry separation mechanism, strictly specifies each and every step of the procedure, such as a glassware setup, heating and cooling rates, etc. Meanwhile, crystallization elution fractionation (CEF), a newly developed technique, is capable of quantifying polyolefin structural regularity and comonomer distribution in a fast and automated manner. There have been a few pieces of preliminary work aiming to provide XS value from the CEF test with a limited number of samples. It is important to gain deep insights into the relationship between XS and the purge fraction of CEF by studying a large number of diverse polypropylene materials. In this paper, close to 300 commercial polypropylene and/or homemade polypropylene, both homopolypropylene (hPP) and propylene-ethylene copolymers (P/E) made with various catalysts under different conditions, were employed. XS values were obtained via CRYSTEX QC calibration. It was found that XS and the soluble fraction (SF) from CEF yielded a linear relationship with R 2 = 0.9942. This linearity is applicable regardless of polymer types, which can differ significantly in terms of molecular weight distribution, tacticity, chemical composition, and melt flow rate. One of the prominent advantages of using the CEF test instead of ASTM D 5492-17 is the elimination of the time-consuming procedure for much-improved precision and high productivity. In addition, the catalytic system was found to have an influence on SF and crystalline fractions of copolymers.

Effect of the synergistic interaction of zinc adipate, hydrotalcite and ethylene propylene rubber on the performances of polypropylene

Polypropylene (PP) is widely used in a range of areas due to its excellent physical and chemical properties, but its low-temperature brittleness and low-impact resistance largely limits its application. Hence, this study investigated the changes in mechanical and thermal properties of isotactic polypropylene (iPP) modified by the addition of the β-nucleating agent zinc adipate (ZnAA), the inorganic rigid particle hydrotalcite (HT), and the rubber elastomer bipropylene rubber (EPR). The structure and properties of modified PP were investigated by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electronic universal material testing machine, and simple-beam impact testing machine. At last, the non-isothermal crystallization kinetics of iPP was investigated by the Caze method. It was found that with the addition of EPR reached 30 wt%, the notched impact strength of iPP was 34.74 kJ/m2, which was 542.43 % higher than that of pure iPP, and more than twice as high as that of ZnAA and HT modification, and the relative crystallinity ( K β) value of the β-crystalline form reached 79.66 % when 10 wt% EPR was added to the iPP. The addition of ZnAA, HT and EPR could significantly increase the crystallisation peak temperature ( T c), shorten the half-crystallisation time ( t 1/2) and increase the crystallisation activation energy ( ΔE) of iPP.

Dielectric performance improvement of polypropylene film by hierarchical structure design for metallized film capacitors

In this paper, hierarchical structure design method is proposed for improving the dielectric performance of polypropylene (PP) for metallized film capacitors. The results show that the composite film with 0.02 wt% terephthalaldehyde doping and functional layer thickness occupying 25% shows the best dielectric properties. The leakage conductivity declines by 89.0%–94.3%, the DC breakdown strength grows by 15.6%–19.7% and the discharged energy density improves by 50.6%–53.4%. Terephthalaldehyde doping introduces sites that could capture free holes, thereby blocking the carrier migration path. The hierarchical structure design results in the holes accumulating in the functional layer and the reverse electric field formed suppresses the charge injection from the anode. Furthermore, the probability of intrinsic charge excitation due to the band gap width reduction is greatly reduced. The method provides a reference for improving the dielectric performance of PP films from the perspective of regulating the charge transmission behavior.

Study on thermal cycling ageing resistance of performances of polypropylene/elastomer/boron nitride nanocomposites for high voltage direct current cable insulation

AbstractThe influences of thermal cycling ageing on structures and insulation performances of polypropylene (PP)/elastomer/boron nitride (BN) nanocomposites are investigated. The Melt blending method was used to prepare the nanocomposites, in which propylene‐based elastomer (PBE) or ethylene‐octene copolymer elastomer (EOC) was contained for comparison. Then, the samples were treated using a thermal cycling process with a temperature range from −30 to 150°C, and the number of thermal cycles was set from 0 to 15. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry and X‐ray diffraction measurements were taken to facilitate the comprehension of structural changes. Additionally, measurements were taken to assess the trap distribution and direct current (DC) breakdown strength of the samples. The obtained results revealed that following thermal cycling ageing, the morphology and crystallinity of PP/PBE/BN remained almost unchanged. In contrast, PP/EOC/BN exhibited substantial microstructural damage accompanied by a significant reduction in crystallinity. As the number of thermal cycles increased, the trap level and DC breakdown strength of PP/PBE/BN were maintained at high levels, while those of PP/EOC/BN initially remained stable but then experienced a sharp decline. It is suggested that the addition of BN nanoparticles enhances the thermal cycling ageing resistance of the PP/PBE blend, whereas it weakens this resistance of the PP/EOC blend.

Preparation of a High‐Performance Anti‐Aging Polypropylene Composite with Titanium Oxide and Calcium Sulfate Shielding Agents

AbstractPolypropylene is a thermoplastic synthetic resin that is widely used across industries. However, it tends to fracture easily and get oxidized under ultraviolet light and high temperatures. This not only reduces its service life but also causes pollution and waste. Although the use of TiO2 as a shielding agent has improved the aging performance of PP composite materials, it still has poor mechanical and processing properties that do not meet the actual demand for high‐performance polypropylene.This limitation seriously impacts the development of polypropylene products. In this paper, we propose the use of the ATRP method with UV shielding titanium dioxide (TiO2) and high‐toughness calcium sulfate whiskers (CSW) coated with coupling agent KH570 surface modification after grafting acrylonitrile (AN). This material has a dual shielding effect on UV light. TiO2‐PAN (TP) mainly plays the role of anti‐aging, whereas CSW‐PAN(CP) mainly enhances the compatibility and mechanical strength between TP and CP. Additionally, CP has a certain UV shielding function due to grafting acrylonitrile. When added to PP in a certain proportion, TP and CP work together to improve the overall performance of polypropylene.

Influence of graphene nanoplatelets (GnPs) and titanium dioxide (TiO2) hybrid fillers on the mechanical, thermal, and morphological performance of polypropylene (PP) based hybrid composites

The main objective of the present study was to investigate the influence of graphene nanoplatelets (GnPs), Titanium dioxide (TiO2), and its hybrid filler on the mechanical, thermal, and morphological characteristics of polypropylene (PP) based hybrid composites for structural applications. The PP-based hybrid composites were prepared using a twin-screw extruder for different filler compositions and then molded into tensile specimens with a mini-jet injection molding setup. Tensile, thermal, and morphological analyses were performed to determine the hybrid capability of the PP-based composites. The results showed that the values of tensile modulus and tensile yield strength show significant improvement at about ∼24% and ∼17%, while the values of elongation at break show a slightly decreasing trend for the hybrid composites compared to PP composites. The thermal stability analysis shows that the higher the hybrid filler content, the higher the temperature. Further, the SEM micrographs for the hybrid fillers show good dispersion onto the PP matrix, which may increase the interfacial adhesion between PP and fillers, thus enhancing the mechanical and thermal properties of PP-based hybrid composites.

Corrigendum to “Influence of graphene nanoplatelets (GnPs) and titanium dioxide (TiO2) hybrid fillers on the mechanical, thermal, and morphological performance of polypropylene (PP) based hybrid composites”

Corrigendum to “Influence of graphene nanoplatelets (GnPs) and titanium dioxide (TiO₂) hybrid fillers on the mechanical, thermal, and morphological performance of polypropylene (PP) based hybrid composites”

Enhancement of ductility characteristics of fiber-reinforced ternary geopolymer mortar

There is a need for ambient-cured geopolymer as a potential replacement for conventional ordinary Portland cement (OPC) based concrete. But geopolymers, that belong to the ceramic family, behave in a brittle manner and hence this research focusses on the enhancement of ductility using fibers. Thus, this experimental work was conducted to investigate the performance of polypropylene (PP) and micro steel fiber (MS) of fiber-reinforced geopolymer mortar (FRGM) on the hardened properties. The volume fractions of fiber used were 0%, 0.5%, 1%, and 1.5%. The ternary blended geopolymer mortar consisted of fly ash (FA), ground granular blast furnace slag (GGBS), and palm oil fuel ash (POFA). The hardened properties investigated are compressive strength, splitting tensile strength, modulus of elasticity (MoE), and ultrasonic pulse velocity (UPV). Furthermore, the load-deflection response was investigated in terms of deflection, load, flexural, and toughening mechanisms. The morphology of matrix mortar with the bonding of the fibers was examined through field emission scanning electron microscope (FESEM). The results revealed that the splitting tensile strength was enhanced with the inclusion of 0.5% of PP fibers and up to 1.5% of MS fibers by 27% and 177%, respectively. The enhancements in the ultimate flexural strength with 1.5% fiber were found 173% and 33% higher for MS and PP fibers, respectively compared to the control mixes. The inclusion of both MS and PP fibers showed a significant enhancement in the post-cracking flexural and toughness energy measured at L/150 mm. Furthermore, the addition of fiber volume of 0.5–1.5% enhanced the toughness by 33% (T600), 62% (T150), and 28% (T600), 46% (T150) for MS and PP mixes, respectively.

Significantly improved high-temperature capacitive performance in polypropylene based on molecular semiconductor grafting

The high-temperature dielectric properties and energy storage performance of capacitive materials are of great significance for the sustainable development of new energy-related fields. However, the most widely used commercial capacitor dielectric biaxially oriented polypropylene (BOPP) films fail to satisfy the requirements of continuous operation above 105 °C at high electric fields. Here we demonstrate a molecular semiconductor-grafted polypropylene (PP) composite that possesses substantially enhanced dielectric and capacitive performance up to 120 °C by virtue of the modulated carrier transport behavior. The organic molecular semiconductor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is chemically grafted onto PP chains (PCBM-g-PP) to achieve strong interaction and decent compatibility between the PCBM and the polymer matrix. Based on computational simulation and experimental verification, it is confirmed that the grafted molecular semiconductor introduces deep traps to inhibit the migration of high-energy charge carriers excited by heat. In the meantime, the grafting also helps to intensify the regulation effect by exerting positive influences on the microstructure of the polymer. The PCBM-g-PP/PP composite films possess reduced leakage current and dielectric loss, as well as suppressed electric field distortion and elevated breakdown strength. At 120 °C, the energy storage density of the composite with an efficiency above 90% reaches 1.59 J/cm3, which is 683.62% that of the original PP film. The reported molecular semiconductor-grafting strategy is expected to promote the capacitive performance of polypropylene under hash-temperature conditions, facilitating the development of lightweight and compact-size dielectric capacitors.

Enhancement of fire resistance and mechanical performance of polypropylene composites containing cellulose fibres and extracellular biopolymers from wastewater sludge

In the present research, a bio-based flame retardant (FR) was prepared using a biopolymer derived from wastewater sludge to improve the fire performance of polypropylene (PP). Extracellular polymeric substances (EPS), which were extracted from wastewater aerobic granular sludge, were absorbed into cellulose-based fibres, such as flax and toilet papers. Thermogravimetric analysis results indicated that the EPS-cellulose fibres played a significant role in enhancing the char formation of PP composite. Furthermore, the incorporation of the bio-based FR into PP restricted its vertical burning characteristics, and at the same time enhanced the tensile moduli of the composites. The reaction between phosphoric acids from EPS and hydroxyl groups of cellulose fibres improved dehydration and char formation of the composites to enhance the overall fire reaction properties. This study opens up new possibilities for the wastewater-derived biopolymer “EPS” to prepare the bio-inspired FRs for cellulose-based fibres and composites, and enhance sustainability of wastewater sludge treatment.

Microwave heating of silicon carbide and polypropylene particles in a fluidized bed reactor

Microwave-assisted recycling of plastics has become an increasingly attractive technology. In this study, the effects of microwave power, fluidization velocity, particle size and mass ratio on heating performances of polypropylene (PP), silicon carbide (SiC), and the binary mixed (PP/SiC) particles in a microwave fluidized bed reactor were experimentally investigated. The maximum temperature of SiC particles was increased when the microwave power, particle size increased and fluidization velocity decreased. The maximum temperature of SiC particles was 965.7 °C in this study, whereas the maximum temperature of PP particles was only 113.5 °C, and the heating rate of SiC particles was about 7.8–77.2 times that of PP particles. For SiC/PP mixture particles, when the microwave power was 400 W, fluidizing velocity was 3.54 × 10−3 m/s, and the mass ratio of SiC-to-PP was 40:5, the temperature of the mixture particles increased to 600 °C rapidly and then fixed at 600 °C. However, when the fluidizing velocity was slow (1.18 × 10−3 m/s) or the mass ratio was changed (40:1 and 40:10), the temperature decreasing phenomenon appears during the microwave heating process of mixture particles.

Polypropylene/Date Palm Fiber Nano Filler Biocomposites: Investigation of some Rheological Aspects

Rotational rheology was used to analyze the performance of polypropylene (PP) composites reinforced with date palm nanofiber (DNF) in the molten state in this study. In the first stage, mechanical ball milling was used to obtain date nanofillers with average filler sizes ranging from 30–110 nm in width and 1–10 mm in length. Dry blending technique was used to reinforce this filler to the polypropylene in the 1-5wt. % loading. The resulting PP/DNF biocomposites were subsequently tested using a rotating rheometer with a 25 mm parallel plate geometry. The broad range of angular frequency from 0.1 rad·s−1 to 100 rad·s−1 was applied to study their complex viscosity (η*) at a fix strain (1%). The decrease in complex viscosity with angular frequency in all the samples was observed compared to the neat PP. The complex viscosity of the neat PP and the 5 wt.% of filler samples at 0.1 rad·s−1 frequency was found to have 18170 Pa. s and 5335 Pa. s, respectively. Therefore, this analysis revealed that this biocomposites exhibits typical viscoelastic behavior of entangled polymeric liquid.

Sliding wear performance of novel millet husk reinforced polypropylene composites

The current research aims to investigate the influence of novel millet husk, finger millet husk (FMH), and barnyard millet husk (BMH) as fillers on the sliding wear performance of polypropylene (PP) composites. The composites were prepared with 10 wt% loading of FMH and BMH by the extrusion injection molding (EIM) process. The sliding wear testing was performed at different combinations of sliding velocity (0.5, 1, and 1.5 m/sec), load (10, 20, and 30 N), and sliding distance (300 m) against the 1000-µm silicon carbide abrasive paper as counter surface. It was observed from the micrographs that FMH and BMH established improved adhesion with the PP matrix and lowered the specific wear rate. At higher load and velocity values, tribofilm development was observed, which lowered the rate at which composites wear out. The wear mechanism, bonding behavior, and worn-out surface have also been discussed and supported with surface analysis using a scanning electron microscope.

Study on the Fatigue Strength of Welding Line in Injection Molding Products under Different Tensile Conditions.

The fatigue performance of polypropylene (PP) at various amplitudes and frequencies on fatigue cycles under tensile test conditions is investigated in this study. The results show that increasing the frequency leads to a decrease in fatigue cycles due to increased cycle time. The decline rate can be divided into two stages, between 1 and 5 Hz. The first stage rapidly decreases fatigue performance as the frequency increases from 1 Hz to 2 Hz or 3 Hz. The second stage has a lower reduction rate, which occurs between 2 Hz or 3 Hz and 5 Hz due to the strengthening effect of increasing frequency. Furthermore, increasing the amplitude from 0.1 mm to 0.4 mm reduces the fatigue cycle due to the higher deformation rate. In summary, expanding both amplitude and frequency reduces the fatigue performance of the PP material. Moreover, according to the scanning electron microscope microstructure, increasing the frequency results in more microcracks in the polymer matrix.

Electrochemical noise analysis to evaluate the localized anti-corrosion properties of PP/graphene oxide nanocomposite coatings

• Electrochemical noise was used to evaluate the localized corrosion of PP-based NCCs. • PP|Graft|GO = 0.1 illustrated the best localized corrosion performance. • PP|Graft|GO = 0.1 was able to re-passive and prevent the growth of large & deep pits. • In the presence of GO, the transients shift to the higher frequencies at all times. Electrochemical noise analysis was applied to evaluate the localized anti-corrosion performance of polypropylene (PP)-based nanocomposite coatings (NCC). In this regard, the NCCs were developed on mild steel from a solution containing PP, MAH-grafted PP, and different percentages of graphene oxide (GO). The coated samples were subjected to thermal tests, salt spray, and electrochemical noise (EN) analysis. Electrochemical potential and current noise (EPN & ECN) signals were evaluated to find information about localized corrosion. First, the raw signals were analyzed based on the empirical mode decomposition (EMD), then the 3D diagrams (intensity, time, and frequency) were plotted using the Hilbert transform. The results showed in the presence of GO, the transients shift to the higher frequencies at all times, which confirms more tendency to uniform corrosion instead of localized. Introducing 3 wt% of GO NPs into the coating leads to the electrochemical noise resistance increasing by 5 times (>10 8 Ω.cm 2 ), pit initiation rate decreasing, and pit radius reduction (by ∼5 times). As a result, MAH-grafted PP and GO in these NCCs can act as effective barriers against corrosive agents, especially the agents that cause pitting corrosion.

Improving Polypropylene Matrix Composites Reinforced with Aligned Hemp Fibre Mats Using High Fibre Contents.

The main goal of this study was to improve the mechanical performance of polypropylene (PP) matrix composites through high hemp fibre content. In order to achieve high fibre content, the possibilities of different polymer sheet thicknesses and stacking arrangements were investigated. It was found that decreasing the overall thickness of fibre mats between two polymer sheets within the stacking arrangements of composites and so decreasing the distance the polymer needs to travel improved the fibre wetting and therefore improved the tensile properties. The strongest composite produced had a fibre content of about 60 wt%. At this fibre content, tensile strength and Young’s modulus of the composites were found to be 3.0 and 6.9 times, respectively, higher than the control samples (polymer only samples), while figures for flexural strength and flexural modulus were 3.4 and 3.6, respectively.

Fabrication of hierarchical core–shell carbon microspheres@ layered double hydroxide@ polyphosphazene architecture in flame‐retarding polypropylene

Developing advanced performance polypropylene (PP) composites with less smoke, eco-friendly and efficient flame retardants (FRs) has been a growing focus of research. In particular, it was significant to reduce the emissions of smoke and toxic gases generated during the burning of PP so that it meets green and safe industrial requirements. In this work, a CMSs@LDH@PZN hierarchical core–shell framework was designed and synthesized by using carbon microspheres (CMSs) and layered double hydroxides (LDHs) nanosheets connected to CMSs by electrostatic forces with polyphosphazene (PZN). The structure, composition and morphology of CMSs@LDH@PZN were characterized by SEM, TEM, FT-IR, XRD and TG, and the results were shown the triumphant preparation of the well-designed hierarchical core–shell structure CMSs@LDH@PZN. Additionally, the total smoke production, peak heat release rate and total heat release rate of PP/CMSs@LDH@PZN composites were decreased by 56.2%, 41% and 43.4%, respectively. With the addition of 20 wt% CMSs@LDH@PZN alone, the PP/CMSs@LDH@PZN composites reached a V-0 rating in the Vertical combustion tester (UL-94), and had a limiting oxygen index (LOI) value of 29.6%. Moreover, the heat release and toxic smoke emission were significantly lessened, which can be own to the adsorption of core–shell hybrid materials and the barrier effect of the P and N element crosslinked carbon layer. Herein, this work extends the idea of preparing multipurpose high-performance composites and designs and synthesizes an eco-friendly and efficient flame retardant with a double shell structure.

Study on the Weathering Performance of Polypropylene by Artificial Accelerated Aging and Natural Aging

Study on the Weathering Performance of Polypropylene by Artificial Accelerated Aging and Natural Aging

Dielectric Property and Breakdown Strength Performance of Long-Chain Branched Polypropylene for Metallized Film Capacitors.

At high temperatures, the insulation performance of polypropylene (PP) decreases, making it challenging to meet the application requirements of metallized film capacitors. In this paper, the dielectric performance of PP is improved by long-chain branching modification and adding different kinds of nucleating agents. The added nucleating agents are organic phosphate nucleating agent (NA-21), sorbitol nucleating agent (DMDBS), rare earth nucleating agent (WBG-Ⅱ) and acylamino nucleating agent (TMB-5). The results show that the long-chain branches promote heterogeneous nucleation and inhibit the motion of molecular chains, thereby enhancing the dielectric properties at high temperatures. Nucleating agents modulate the crystalline morphology of long-chain branched polypropylene (LCBPP), which leads to a decrease in the mean free path of carriers and an increase in trap energy level and trap density. Therefore, the conductivity is reduced and the breakdown strength is improved. Among the added nucleating agents, NA-21 showed a significant improvement in the electrical properties of LCBPP films. At 125 °C, compared with PP, the breakdown strength of the modified film is increased by 26.3%, and the energy density is increased by 66.1%. This method provides a reference for improving the dielectric properties of PP.

Phytonutrient content, antioxidant potential and acceptability of muffins functionalized with soy and citrus industry waste

The study aimed to effectively utilize soy (okara) and citrus juice (citrus peel) industry waste for developing functionalized bakery product. Muffins were prepared using composite flours having okara along with candied citrus peel. Flours were evaluated for the change in techno-functional properties with increasing level of okara addition. Muffins were analyzed for their physical, chemical, functional and sensory characteristics. Muffins with 15% okara with 2% candied citrus peel were found to be highly acceptable with improved protein (12.70%), dietary fiber (8.26%), total mineral (1.86%), phenols (88.12 mg 100 g−1) and flavonoid content (96.31 μmole Trolox 100 g−1) with insignificant changes in mouthfeel and total calorific value. Majorly, citrus peel contributed to the antioxidants (phenols and flavonoids) of functionalized muffins. Okara addition resulted in ~22% increase in protein and ~45% increase in dietary fiber content of the muffins. Performance of polypropylene was superior over cling film in terms of muffin quality during 9 days ambient storage. Functionalized muffins, high in protein, dietary fiber, total ash and antioxidants, can be developed by effective utilization of waste from soy (okara) and citrus juice industry (citrus peel). The naturally colored candied peel can serve as an alternate to the synthetically colored tutti fruitti that is added to the baked products to improve their appearance and taste. Almost similar baking losses and raw material input cost associated with the optimized product shows its possible adoption by any bakery industry. Practical applications Functionalized muffins, high in protein, dietary fiber, total ash and antioxidants, can be developed by effective utilization of waste from soy (okara) and citrus juice industry (citrus peel). The naturally colored candied peel can serve as an alternate to the synthetically colored tutti fruitti that is added to the baked products to improve their appearance and taste. Almost similar baking losses and raw material input cost associated with the optimized product shows its possible adoption by any bakery industry.