Properties of PEG/thermally modified wood flour/polypropylene (PP) composites

In order to improve the dimensional stability of wood-polymer composites, wood flour pre-treated by polyethylene glycol （PEG） at two different concentrations and then thermally treated at 140℃, was used as raw material to produce wood flour/poly- propylene （PP） composites at a wood content of 40%. The structure of modified wood flour was analyzed with a scanning electron microscope （SEM） and its effect on the physical and mechanical properties of wood flour/PP composites was evaluated. The SEM results indicated the ＂bulking＂ effect of PEG on wood flour, which resulted in reduced water uptake. The combination of PEG and heat treatment further improved the moisture resistance of the composites. However, PEG modification had a negative effect on the flexural modulus of rupture （MOR） and the modulus of elasticity （MOE）; whereas heat treatment partly compensated for this reduc- tion. For dynamic mechanical properties, PEG treatment decreased the storage modulus （E＇）. However, the heat treatment resulted in an increase orE＇ of the wood flour/PP composites, with the temperature of loss factor peaks shifting to a higher temperature.

Preparation of Ultra-nano Talcum in Sand Mill and Its Application in the Polypropylene

The grinding of ultra-fine talcum powder and its application in a polypropylene （PP） matrix were investigated. Ultra-fine talcum powder was prepared by adjusting the grinding parameters of the physical milling process. The talcum powder exhibited polymodal distribution. The layered morphology of talcum particles in a horizontal sand mill was rarely damaged or destroyed. PP-talcum nanocomposites were prepared by melt blending using a twin-screw extruder. Nano talcum can be seen as a single particle, although it is not very apparent. The bending strength of talcum-filled PP was gradually increased by approximately 28%. The impact strength linearly decreased as the filler weight ratio increased. The overall maximum improvement in mechanical properties was recorded when the filler ratios increased from 15 wt% to 20 wt%.

Functionalization of Polypropylene with High Dielectric Properties: Applications in Electric Energy Storage

Biaxial-oriented polypropylene (BOPP) thin films are currently used as dielectrics in state-of-the-art capacitors that show many advantages, such as low energy loss and high breakdown strength, but a limited energy density ( 600 MV/m. The PP-OH dielectric demonstrates a linear reversible charge storage behavior with high releasing energy density > 7 J/cm3 (2 - 3 times of BOPP) after an applied electric field at E = 600 MV/m, without showing any significant increase of energy loss and remnant polarization at zero electric field. On the other hand, a cross-linked polypropylene (x-PP) exhibits an ε ~ 3, which is independent of a wide range of temperatures and frequencies, slim polarization loops, high breakdown strength (E = 650 MV/m), narrow breakdown distribution, and reliable energy storage capacity > 5 J/cm3 (double that of state-of-the-art BOPP capacitors), without showing any increase in energy loss.

Preliminary study of viscoelastic properties of MAPP-modified wood flour/polypropylene composites

Viscoelastic properties of maleated polypropylene （MAPP）-modified wood flour/polypropylene composites （WPC） were investigated by both a compression stress relaxation method and dynamic mechanical analyses （DMA）. Three wood to polymer ratios （40：60, 60：40, and 80：20） and five MAPP loading levels （0, 1, 2, 4 and 8%） were used to study their effects on the viscoelastic prop- erties of MAPP-WPC. The results show that： 1） higher wood to polymer ratio corresponds to higher stress relaxation levels for unmodified WPC. The modification with MAPP has an obvious effect on the stress relaxation of MAPP-WPC at higher wood to polymer ratios （60：40 and 80：20）, but almost no effect at the 40：60 wood to polymer ratio. The optimal MAPP loading level for the wood to polymer ratio of 60：40 appears at 1%; 2） the storage modulus reaches its maximum at a MAPP loading level of 1% for wood to polymer ratios of 40：60 and 60：40, while for the 80：20 wood to polymer ratio, a higher storage modulus is observed at higher MAPP loading levels, which is quite consistent with the stress relaxation results. The results suggested that a suitable loading level of MAPP has a positive effect on the viscoelastic properties of WPC at higher wood to polymer ratios. Excessive MAPP loading would have resulted in adverse effects.

Development and Application of Expanded Polypropylene Foam

The products of expanded polypropylene（EPP） is widely explored and used. the PP modification methods, the preparation methods of EPP and the molding technology of EPP were reviewed. The application of EPP in the field of sporting equipment were also discussed. This paper may provide theoretical foundation for the applications and developments of EPP.

Coupling effect of pond ash and polypropylene fiber on strength and durability of expansive soil subgrades:An integrated experimental and machine learning approach

This study explores the coupling effect of pond ash(PA)and polypropylene(PP)fiber to control the strength and durability of expansive soil.The PA is used to chemically treat the expansive soil and PP fiber is adopted as reinforcement against tensile cracking.The sustainable use of PA and PP fiber are demonstrated by performing mechanical(i.e.unconfined compressive strength,split tensile strength and ultrasonic pulse velocity),chemical(pH value,electrical conductivity and calcite content),and microstructural analyses before and after 2nd,4th,6th,8th and 10th freezing-thawing(F-T)cycles.Three curing methods with 7 d,14 d and 28 d curing periods are considered to reinforce the 5%,10%,15%and 20%PA-stabilized expansive soil with 0.25%,0.5%and 1%PP fiber.In order to develop predictive models for mechanical and durability parameters,the experimental data are processed utilizing artificial neural network(ANN),in association with the leave-one-out cross-validation(LOOCV)as a resampling method and three different activation functions.The mechanical and durability properties of the PA-stabilized expansive soil subgrades are increased with PP fiber reinforcement.The results of ANN modeling predict the mechanical properties perfectly,and the correlation coefficient(R)approaches up to 0.96.

One-step synthesis of hydrophobic magnesium hydroxide nanoparticles and their application in flame-retardant polypropylene composites

Hydrophobic magnesium hydroxide(MH) nanoparticles were prepared by a one-step synthesis method in a high-gravity environment generated by a novel impinging stream–rotating packed bed(IS-RPB) reactor. The reactant solutions were simultaneously and continuously pumped into the IS-RPB reactor, and then Tween80 was added as a surface modifier. The morphology, structure, and properties of blank and hydrophobic MH were characterized. The effects of MH nanoparticles on the flame retardancy, thermal stability, and mechanical properties of PP/MH composites were also studied. We found that the obtained MH nanoparticles exhibited hexagonal lamella with a mean size of 30 nm, excellent hydrophobic properties(e.g., high water contact angle of 112°), and improved thermal stability of MH. The limiting oxygen index(LOI) further showed that increased MH loading can significantly improve flame-retardant performance, which reached 29.3% for PP/MH composites with 30 wt% hydrophobic samples. The thermal stability and mechanical properties of the PP/MH composites with hydrophobic samples were also much higher than those of PP/MH composites with blank MH. Results showed that the one-step synthesis had high potential application in the large-scale production of hydrophobic MH nanoparticles.

Alternative Diesel Grade Fuel Transformed from Polypropylene (PP) Municipal Waste Plastic Using Thermal Cracking with Fractional Column Distillation

Day by day worldwide use of plastics is increasing because of their light weight and durable characteristics. Waste plastics are major environmental problems all over the world. Waste plastics are not bio-degradable, it remains in the landfill for a long period of time causing vegetation and aquatic ecosystem dilemmas. Abandoned waste plastic thrown into the ocean causes friction of ocean waves and then broken down by sunlight into small pieces and takes the shape of plastic like soup. Aquatic organism mistakes the plastic soup as their food and can’t digest, either they die or through food chain it affects human health. To avoid severe environmental degradation problems of waste plastics some countries and big cities banned or restricted the use of plastic products. The worldwide generation of waste plastics is approximately 280 million tons/year. All most all of these waste plastics are dumped either in land or ocean. City municipalities spend huge amount of money each year just to dispose of these waste plastics into landfill because most waste plastics are not recycled. When the waste plastics are subjected to incineration, they release harmful toxic gas into the environment causing severe pollution. These waste plastics gradually enhance the hazardous environmental problems. Generally plastics are made from crude oil, however crude oil is a very limited natural resource and non-renewable. Every year millions of barrels of crude oil are to produce the waste plastics and when plastics are discarded after use the energy source is lost. A new developed technology plan minimizes the environment pollution problems simultaneously boost up energy sector by renovating the waste plastics into high energy content fuel. The produced fuel is obtained using a unique thermal degradation of waste plastics and converting them into hydrocarbon fuel like materials. Preliminary tests proved that this fuel burns cleaner and the production cost is very low. Unique production setup demonstrated to produce 93% fuel from waste plastic in the pilot scale. The Fuel produced has been tested and proven to work on majority types of internal combustion engines. This technology utilized can avoid waste plastic pollution problem worldwide by the implementation of newly developed technology. Through the utilization of the technology the use of reliable plastics won’t need to be banned and serve as a very reliable alternate source of energy. The technology will also help reduce a significant amount of import oil from foreign countries and help provide a steady economy.

A Novel Approach for Observing Morphology of Polypropylene under Ultrasonic Vibration by SALS

In this paper, a set of ultrasonic vibration device connecting with small angle light scattering(SALS) for in-situ observing phase-transition of polymer under ultrasonic vibration was established. The experiments for verifying polypropylene(PP) indicated that ultrasonic vibration resulted in the decrease of the crystallization rate and made PP crystallizable at low temperature.

Application of FTA based on SDG-HAZOP for production of polypropylene

The SDG-HAZOP(Signed Directed Graph,Hazard and Operability Analysis) is a qualitative safety assessment method,which is comprehensive,systematic and complete.However the result is tedious and large.Fault tree analysis(FTA) is a logical and diagrammatic method,which is proved to be a useful quantitative analysis tool to evaluate the safety and reliability of complex systems.So a FTA based on SDG-HAZOP quantitative method was proposed in this paper.Firstly,the SDG-HAZOP and the FTA were established on the background of polypropylene production devices in the Sinopec Wuhan Branch.Secondly,the probability of top event was calculated by reliable data from the probability of basic events.Finally,the targeted measures were proposed to prevent fatal potential dangerous situations by probability calculation.

Mechanical, Thermal and Crystallization Properties of Polypropylene (PP) Reinforced Composites with High Density Polyethylene (HDPE) as Matrix

Our work aims to evaluate a complete outlook of virgin high density polyethylene (HDPE) and polypropylene (PP) polyblends. Virgin PP of 20, 30 and 50 weight% is compounded with virgin HDPE. The properties like tensile strength, flexural strength, Izod impact strength are examined. Scanning electron microscopy (SEM) and polarised light microscopy (PLM) are used to observe the surface and crystal morphology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) tests verify the non compatibility of both polymers. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques are used to study the thermal behaviour of composites. The results manifest co-occurring spherulites for polyblends;indicating the composite to be a physical blend of continuous and dispersed phases, but on the other hand PP improves the tensile and flexural properties of HDPE.

Interpenetrating polymers supported on microporous polypropylene membranes for the transport of chromium ions

Modifying polypropylene membranes with interpenetrating polymer networks(IPNs) through the incorporation of poly(glycidyl methacrylate-N-methyl-D-glucamine)(P(GMA-NMG)) was performed by in situ synthesis via radical polymerization. The surface of the polypropylene membrane was activated by hydrophilic grafted polyelectrolyte, and then, pressure injection was used for the impregnation of the reactive solution in the membrane.Two types of pore-filled membranes were synthesized, chelating interpenetrating homopolymer networks of P(GMA-NMG), and chelating-ion exchange interpenetrating polymer networks(e.g., P(GMA-NMG)/P(AA),P(GMA-NMG)/P(AMPSA), and P(GMA-NMG)/P(Cl VBTA)). After their synthesis, the modified polypropylene membranes were characterized using techniques such as the electrokinetic potential, SEM, FT-IR, and Donnan dialysis to corroborate the chromium ion transport. The P(GMA-NMG) and complex network membranes exhibited a hydrophilic character with a water-uptake capacity between 20% and 35% and a percentage of modification between 4.0% and 7.0% in comparison with the behavior of the unmodified polypropylene membrane.Hexavalent chromium ions were efficiently transported from the food chamber at p H 9.0 when the 65.2%MTA1 P(Cl VBTA) homopolymer IPN membrane and 48.5% MTAG P(GMA-NMG)/P(Cl VBTA) IPN membrane were used. Similarly, hexavalent chromium ions were removed from the food chamber at pH 3.0 when MTAG(63.30%) and MTA1(35.68%) were used in 1 mol·L^(-1)Na Cl solution as the extraction reagent.

Exploring the effect of cooling rate on non-isothermal crystallization of copolymer polypropylene by fast scanning calorimetry

Polypropylene is commonly used as a binder for ceramic injection molding,and rapid cooling is often encountered during processing.However,the crystallization behavior of polypropylene shows a strong dependence on cooling rate due to its semi-crystalline characteristics.Therefore,the influence of cooling rate on the quality of final product cannot be ignored.In this study,the fast differential scanning calorimetry(FSC)test was performed to study the influence of cooling rate on the non-isothermal crystallization behavior and non-isothermal crystallization kinetics of a copolymer polypropylene(PP BC03B).The results show that the crystallization temperatures and crystallinity decrease as the cooling rate increases.In addition,two exothermic peaks occur when cooling rate ranges from 30 to 300 K·s^(-1),indicating the formation of another crystal phase.Avrami,Ozawa and Mo equations were used to explore the non-isothermal crystallization kinetics,and it can be concluded that the Mo method is suitable for this study.

Characterization and Modeling of Mechanical Properties of Additively Manufactured Coconut Fiber-Reinforced Polypropylene Composites

In the face of the increased global campaign to minimize the emission of greenhouse gases and the need for sustainability in manufacturing, there is a great deal of research focusing on environmentally benign and renewable materials as a substitute for synthetic and petroleum-based products. Natural fiber-reinforced polymeric composites have recently been proposed as a viable alternative to synthetic materials. The current work investigates the suitability of coconut fiber-reinforced polypropylene as a structural material. The coconut fiber-reinforced polypropylene composites were developed. Samples of coconut fiber/polypropylene (PP) composites were prepared using Fused Filament Fabrication (FFF). Tests were then conducted on the mechanical properties of the composites for different proportions of coconut fibers. The results obtained indicate that the composites loaded with 2 wt% exhibited the highest tensile and flexural strength, while the ones loaded with 3 wt% had the highest compression strength. The ultimate tensile and flexural strength at 2 wt% were determined to be 34.13 MPa and 70.47 MPa respectively. The compression strength at 3 wt% was found to be 37.88 MPa. Compared to pure polypropylene, the addition of coconut fibers increased the tensile, flexural, and compression strength of the composite. In the study, an artificial neural network model was proposed to predict the mechanical properties of polymeric composites based on the proportion of fibers. The model was found to predict data with high accuracy.

Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres

Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete(FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force(up to 18%) while PP micro-fibres slightly increased the peak(3%-4%). FRUHPC significantly reduced the maximum midheight displacement by up to 30%(under 20°impact) and substantially improved the displacement recovery by up to 100%(under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.

Efficient and selective removal of Pb(Ⅱ) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

Utilization of Pineapple Crown Fiber and Recycled Polypropylene for Production of Sustainable Composites

Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the environment.Considering the large number of available biofibers in nature,their use in the development of polymeric composites has inevitably emerged,it is also necessary to take into account the countless discarded plastics that still have the potential to be reused.In this work,fibers were extracted from pineapple crown residues and utilized to compose sustainable composites using recycled polypropylene from cups discarded in the trash as a matrix.However,it is known that for good performance,it is necessary to achieve a good chemical interaction between the fiber and the matrix.In order to improve this interaction,alkaline mercerization treatment was carried out on the surface of the fibers removing some components incompatible with the polymer.In this work,the effect of the mercerization treatment on the properties of the fibers was studied,as well as their interaction with the matrix.The effect of fiber concentration on the mechanical and thermal properties of composites was also evaluated.Levels of 5 and 7 wt%were used for both natural and mercerized fibers.A decrease in the number of degradation stages was observed through thermogravimetry analyses(from four in natural fiber to two in mercerized fibers),showing that the mercerization performed on the fibers was effective.An increase in the degree of crystallinity of mercerized fibers was also observed through the results of X-ray diffraction.Both techniques indicate that amorphous compounds,such as hemicellulose and lignin,were partially removed.Through the tensile test,it could be noted that all composites presented higher values of de elastic modulus than recycled polypropylene without added load;however,there were no differences in the elastic modulus between the different types of fibers and load levels.Therefore,it is interesting to use fibers as reinforcing agents in polymers;however,the treatment did not increase the mechanical properties of the composites.In parallel,other factors,such as the dispersion of the components,must be taken into account to justify this result.

Effects of cement content, polypropylene fiber length and dosage on fluidity and mechanical properties of fiber-toughened cemented aeolian sand backfill

Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the toughening effect of fibers is analyzed,their influence on the slurry conveying performance should also be considered.Additionally,cement affects the interactions among the hydration products,fibers,and aggregates.In this study,the effects of cement content(8wt%,9wt%,and 10wt%)and PP fiber length(6,9,and 12 mm)and dosage(0.05wt%,0.1wt%,0.15wt%,0.2wt%,and 0.25wt%)on fluidity and mechanical properties of the fibertoughened CASB(FCASB)were analyzed.The results indicated that with increases in the three aforementioned factors,the slump flow decreased,while the rheological parameters increased.Uniaxial compressive strength(UCS)increased with the increase of cement content and fiber length,and with an increase in fiber dosage,it first increased and then decreased.The strain increased with the increase of fiber dosage and length.The effect of PP fibers became more pronounced with the increase of cement content.Digital image correlation(DIC)test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure,and reduce the stress concentration of the FCASB.Scanning electron microscopy(SEM)test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers.On the basis of single-factor analysis,the response surface method(RSM)was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS.The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established.In conclusion,the response law of the FCASB properties under the effects of cement and PP fibers were obtained,which provides theoretical and engineering guidance for FCASB filling.

Application of modified polypropylene （crude） fibers concrete to strengthen the support structures in deep mine roadway

The an thors developed a new composite cement base material by mixing the high tenacity polypropylene （coarse） fiber in plain cement base for the cement-layer-spray technology. By studying the key parameters of the fiber dosage, the spray layer thickness, and the fiber reinforced concrete injection time, etc. It is found that the ideal volume ratio of polypropylene （crude） fiber is 0.8% （V/V）, and the secondary lining fiber concrete spraying should start when the shrinkage rate is lower than 0.5 mm/d, and the optimal thickness of shotcrete is 120 mm. The supporting effects and the economic benefits were studied using a real project practice, and the result obtained can be a good reference for practical applications of this new supporting material in the future.

SYNTHESIS AND CHARACTERIZATION OF POLYPROPYLENE/MONTMORILLONITE NANOCOMPOSITES VIA AN in-situ POLYMERIZATION APPROACH

Polypropylene/montmorillonite (PP/MMT)nanocomposites were prepared by in-situ polymerization using aMMT/MgCl_2/TiCl_4-EB Ziegler-Natta catalyst activated by triethylaluminum(TEA). The enlarged layer spacing of MMT wasconfirmed by X-ray wide angle diffraction (WAXD), demonstrating that MMT were intercalated by the catalyst components.X-ray photoelectron spectrometry (XPS) analysis proved that TiCl_4 was mainly supported on MgCl_2 instead of on the surfaceof MMT The exfoliated structure of MMT layers in the PP matrix of PP/MMT composites was demonstrated by WAXDpatterns and transmission electron microscopy (TEM) observation. The higher glass transition temperature and higher storage modulus of the PP/MMT composites in comparison with pure PP were revealed by dynamic mechanical analysis (DMA).