Thermal Stability Of Polypropylene Research Articles

Covalent Bonding Enhanced Polypropylene Based T-ZIF-8 Masterbatch with Superior Photocatalytic and Antibacterial Performances.

In order to solve the problem of poor compatibility between modified-ZIF-8 nanoparticles and mask matrix polypropylene (PP) and melt-blown materials, in this work, PP based modified-ZIF-8 antibacterial masterbatch was prepared employing surface modification and torque blending method. IR, SEM, XRD, XPS, DSC results confirm that the antibacterial masterbatch maintains the chemical and crystal structure of modified-ZIF-8 and the thermal stability of PP. Photocatalytic performance indicates that the antibacterial masterbatch basically maintains the photoresponse range of modified-ZIF-8, has narrower band gap and the superior photocatalytic performance than that of modified-ZIF-8. The photocatalytic antibacterial mechanism of ·O2- and h+ as antibacterial active species is revealed according to the energy band structure and free radical capture experiment. The photocatalytic antibacterial activity of the antibacterial masterbatch against Staphylococcus aureus and Escherichia coli under different dosage holds that the relationship between antibacterial rate and antibacterial agent concentration conforms to Beta distribution, demonstrating second-order kinetic behavior. The antibacterial properties reach the maximum when the loading of modified-ZIF-8 is 2% of the total weight of PP and melt-blown materials. S. aureus and E. coli could be completely killed when the simulated sunlight is irradiated for 30min. These results indicate that PP based modified-ZIF-8 antibacterial masterbatch has potential application in photocatalytic antibacterial masks.

Preparation of Mn2+ Doped Piperazine Phosphate as a Char-Forming Agent for Improving the Fire Safety of Polypropylene/Ammonium Polyphosphate Composites.

A piperazine phosphate doped with Mn2+ (HP-Mn), as a new char-forming agent for intumescent flame retardant systems (IFR), was designed and synthesized using 1-hydroxy ethylidene-1,1-diphosphonic acid, piperazine, and manganese acetate tetrahydrate as raw materials. The effect of HP-Mn and ammonium polyphosphate (APP) on the fire safety and thermal stability of polypropylene (PP) was investigated. The results showed that the combined incorporation of 25 wt.% APP/HP-Mn at a ratio of 1:1 endowed the flame retardant PP (PP6) composite with the limiting oxygen index (LOI) of 30.7% and UL-94 V-0 rating. In comparison with the pure PP, the peak heat release rate (PHRR), the total heat release (THR), and the smoke production rate (PSPR) of the PP6 were reduced by 74%, 30%, and 70%, respectively. SEM and Raman analysis of the char residues demonstrated that the Mn2+ displayed a catalytic cross-linking charring ability to form a continuous and compact carbon layer with a high degree of graphitization, which can effectively improve the flame retardancy of PP/APP composites. A possible flame-retardant mechanism was proposed to reveal the synergistic effect between APP and HP-Mn.

Reactive processing of PA6/EPDM‐MA blends as modifier for application and development of high‐performance polypropylene

AbstractIn this work, PA6/EPDM‐MA was added as an impact modifier for high‐performance polypropylene (PP) production. PA6/EPDM‐MA compounds were processed in an internal mixer, aiming at chemical reaction between maleic anhydride of EPDM‐MA and the amine terminal groups of PA6. Afterward, PP/(PA6/EPDM‐MA) blends were processed by extrusion and injection molding. Rheological properties were evaluated using torque rheometry; additionally, Fourier transform infrared spectroscopy, Molau test, impact and tensile strengths, Shore D hardness, thermal deflection temperature, X‐ray diffraction, differential scanning calorimetry, thermogravimetry, water absorption, contact angle, and scanning electron microscopy tests were performed in injected specimens. PP/(PA6/EPDM‐MA) with 70/(15/15)% displayed quite high increase in impact and elongation at break, with gains of 850% and 265%, compared to neat PP. There were no drastic losses in tensile strength, elastic modulus, and Shore D hardness, due to PA6 addition. A significant increase was seen in the thermal stability of PP/(PA6/EPDM‐MA), corroborating the increase in structural stability seen in HDT. SEM images showed high interfacial adhesion between PP and PA6/EPDM‐MA corroborating higher mechanical properties. Summing up, PA6/EPDM‐MA premix acted as an efficient impact modifier for PP. Acquired data show that P6/EPDM‐MA system was effective in developing high‐performance PP with potential for application in the automotive and electronics industries.

Influence of polypropylene processing conditions on its thermal, physical and mechanical characteristics

The effect of the method and the number of processing cycles on polypropylene thermal and physical-mechanical properties is studied. It is shown that, regardless of the processing method, the thermal stability of polypropylene, expressed by the temperature of the onset of decomposition, decreases, the content of thermally stable compounds increases, and the degree of crystallinity of the polymer decreases by 5.6–6.5%. With an increase in the number of heating-cooling cycles simulating the multiplicity of thermoplastic polypropylene processing, the temperature of the onset of decomposition decreases from 211°C to 166°C, the mass of the sample decreases due to its partial decomposition, the melting point decreases from 166°C to 158°C, the degree of crystallinity of the polymer decreases. With an increase in the number of polypropylene processing cycles by compounding in the mixing chamber of the plastograph, an increase in the load on the rotation of the screws during plasticization and in the melt flow is observed, while the strength and elongation at break of the plastic sample consistently decrease..

A Sustainable Perspective for Macadamia Nutshell Residues Revalorization by Green Composites Development

Macadamia is a nut widely used globally in food, personal hygiene products, and human health. After removing the nut, high amounts of the shell residual, which is an underutilized material with high economic interest. This work presents a sustainable alternative to revalorize the macadamia nutshell residues (MR) developing the green composites. Polypropylene (PP) composites were prepared using different MR content (5, 10, 15, 20, 25, and 30 wt%) as a filler. The samples were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, scanning electron microscopy (SEM), mechanical tests (tensile and flexure) before and after water absorption tests, and Life Cycle Assessment (LCA). FTIR results indicated that the MR acted only by physical impediments, without chemical interactions between the filler and matrix. Thermal analysis showed a significant increase (~ 20 °C) in PP thermal stability after MR addition, probably due to the filler high lignin content, and SEM photomicrographs indicate that high MR contents resulted in little cracks and voids in the interface. However, the defects did not influence the mechanical performance, and the green composites showed superior elastic modulus (2401 MPa) than the pristine PP (1516 MPa) and similar tensile strength (~ 30 MPa), confirmed by the statistical analysis and corroborating with the theoretical percolation network (25 wt%). The composites showed low water absorption (up to 0.3%), reflecting in downward variations in the wet samples' mechanical behavior. It evidences the possibility to use these samples for water applications. LCA indicated that higher MR contents promoted lower environmental impacts than the classical handling of this residue, and the results indicated that 30 wt% MR is the better environmental option. However, the PP/MR-25% showed reduced environmental impacts and associated with other properties improvements, considered the better sample. This work shows the MR revalorization as a sustainable approach to expand green composites applications.

Thermal behavior and kinetic study of plasticized cellulose acetate magnesium hydroxide Polypropylene materials

The thermal stability of polypropylene (PP) materials containing the PP -grafted -maleic -anhydride (PPMA), plasticized cellulose acetate (CA*) and magnesium hydroxide (MH), was investigated. The thermogravimetric analysis (TGA) conducted under air conditions revealed distinct degradation patterns when CA*, MH or MH/CA* were added to PP*. The addition of MH to PP*/CA* improved the thermal stability by shifting the maximum rate of mass loss to a higher temperature. But the MH addition could not counterbalance the lower temperature for the onset of degrada- tion when CA* was blended with PP*. The improved thermal stability of PP*/CA* when MH was added is supported by the higher activation energy (E a ) of the MH/CA*/PP materials. This study also presents a numerical integration method that is recommended to improve the accuracy of E a estimates from TGA data at multiple heating rates. The results indicate that the combined use of MH and CA* leads to materials with the highest thermal stability.

Effect of Halloysite Nanotube on Mechanical Properties, Thermal Stability and Morphology of Polypropylene and Polypropylene/Short Kenaf Fibers Hybrid Biocomposites.

In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and thermal stability of polypropylene (PP) and PP/kenaf fiber biocomposites has been investigated. Different volume contents of HNTs ranging from 1 to 10 vol.% were melt mixed with PP and PP/kenaf fibers. The volume content of kenaf fibers was kept constant at 30%. The morphology of HNTs within the PP matrix has been studied via scanning electron microscopy (SEM). The morphological results revealed that HNT was uniformly dispersed in the PP matrix already at a low concentration of 1 and 2 vol.%. The mechanical properties of the manufactured nanocomposites and hybrid biocomposites such as Young’s modulus, tensile strength, elongation at break, flexural modulus, flexural strength, and notched Izod strength have been measured. The results show that Young’s modulus and strengths have been improved along with the addition of low content of HNTs. Moreover, the gain of notched Izod impact strength obtained by the addition of short kenaf fibers was maintained in hybrids with low concentrations of HNTs. Finally, the thermogravimetric analysis shows that at 10% and 50% weight loss, the thermal degradation rate of the PP and PP/kenaf biocomposites decreased by the addition of HNTs.

Mechanical properties, flame retardancy, and thermal stability of basalt fiber reinforced polypropylene composites

AbstractIn this article, the mechanical properties, flame retardancy, and thermal stability of basalt fiber reinforced polypropylene composites (BFRPPs) and polypropylene (PP) were investigated and compared. The combustion performance and thermal stability of BFRPPs and PP were evaluated by limiting oxygen index (LOI) test, cone calorimeter test (CCT), and thermogravimetric analysis (TGA). The results showed that basalt fibers could enhance mechanical properties, flame retardancy, and thermal stability of PP. With the increase of basalt fiber content, the strength and stiffness of BFRPPs increased significantly, and the elongation decreased obviously. Adding basalt fibers into PP could improve the LOI value. BFRPPs burned appreciably more slowly than PP under the same oxygen concentration. Simultaneously, BFRPPs indicated a better anti‐melt dripping effect than PP matrix. The heat release rate (HRR), total heat release (THR), rate of smoke release (RSR), and total smoke release (TSR) of BFRPPs decreased compared to PP matrix. Moreover, the addition of basalt fibers to PP could contribute to the formation of a more compact and continuous char layer, which effectively reduced the transfer of heat and oxygen, resulting in a better flame retardancy of BFRPPs.

Effect of artemisia argyi charcoal on the mechanical property and thermal stability of polypropylene

ABSTRACTNew polymer composite, composed of artemisia argyi charcoal (AAC) and polypropylene (PP), was produced by extrusion and injection moulding process. ACC acted as filler for PP, and different content (5, 15, 35 and 50 wt-%) of ACC was added. AAC-PP composites (AACPC) were characterised by X-ray diffraction (XRD) analysis, water absorption, scanning electron microscopy (SEM), mechanical test and thermogravimetric analysis (TGA). The sample without the addition of ACC was prepared for comparison. The results indicated that the addition of AAC influenced the crystallinity of PP and the interfacial adhesion between AAC and PP. The water absorption and flexural modulus of AACPC increased with increasing the content of AAC. The flexural strength of AACPC reached 42.0 MPa when the content of AAC was 5 wt-%. Moreover, the incorporation of AAC could improve the thermal stability of PP.

Flame‐retardant effects of cyclic phosphonate with HALS and fumed silica in polypropylene

ABSTRACTIn this study, an N‐alkoxy‐hindered amine‐based UV stabilizing agent (NOR‐116) and nanosized silica particles (Aerosil R‐972) were combined with a cyclic phosphonate based‐flame retardant (FR; PCO‐900) and incorporated into polypropylene via melt extrusion in a microcompounder. In order to stimulate the conditions in the favor of further processing such as fiber spinning, the content of additives in polypropylene was kept low (up to 6.5 wt %). The effects of the PCO‐900, alone and in combination with NOR‐116 and Aerosil‐R972, on the flammability and thermal stability of polypropylene were evaluated by limit oxygen index (LOI) tests, cone calorimetry, and thermogravimetric analysis. The proposed system with 3.5 wt % PCO‐900/1.5 wt % NOR‐116/1 wt % Aerosil‐R972 decreased the heat release, increased the LOI and thermo‐oxidative stability, and, thus, improved the fire resistance of polypropylene. The possible mode of FR activity was also discussed based on the analysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48308.

Influence of graphene‐based compounds on the mechanical toughness and thermal stability of polypropylene

ABSTRACTA study of the improvement of the mechanical and thermal properties of nanocomposites prepared with polypropylene (PP) and different graphene samples [graphene oxide (GO), reduced GO (RGO), and commercial graphene (G)] is presented. X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy characterization were applied to the graphene samples. The nanocomposites were characterized by thermogravimetric analysis, XRD, differential scanning calorimetry, transmission electron microscopy (TEM), tensile, and impact resistance tests. PP/RGO nanocomposites showed significant improvement in mechanical and thermal properties. Sample PP/RGO‐0.75 resulted in an increment in Young's modulus (51%), tensile strength (24%), and elongation at break (15%). This is attributed to a good dispersion state, a higher crystallinity percentage, and a good interfacial adhesion between PP and RGO. Sample PP/RGO‐0.50 exhibited an increase of 197 °C in the temperature at which a loss in weight of 5% occurred, compared to that for pure PP. The height of stacked layers calculated by XRD measurements was similar to the value observed by TEM. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48258.

A study of the thermal degradation of glass fibre sizings at composite processing temperatures

Although not fully understood, it is well recognized that optimal working of glass fibre sizings is necessary to maximize the performance of glass fibre reinforced polymer composites. It is important that the organic components in such sizings continue to function after exposure to the high temperatures often experienced during composite processing. This study presents the results on the thermal stability of polypropylene and epoxy compatible glass fibre sizings obtained using TGA, microbond adhesion measurement and composite mechanical testing. Test results indicate that the performance of commercial polypropylene compatible glass fibre sizings can be significantly compromised by thermo-oxidative degradation at normal composite processing temperatures. A significant reduction in composite performance is directly related to a loss of fibre-matrix adhesion caused by thermal degradation of some of the principal sizing components.

A Facile Approach for Preparing Ag Functionalized Nonwoven Polypropylene Membrane to Improve Its Electrical Conductivity and Electromagnetic Shielding Performance.

The commonly used preparation methods of polypropylene functionalization require special equipment to be put into use or take a long time, which limits its application. Therefore, a simple and economical method for preparing silver functionalized nonwoven polypropylene membrane was studied herein. Triethanolamine was first coated on the surface of the polypropylene, and then Ag was deposited on the surface of polypropylene using a continuous reduction reaction of triethanolamine and silver ions. Surface morphology, crystal structure, and surface chemistry during the preparation of Ag functionalized nonwoven polypropylene were investigated. The electrical conductivity, electromagnetic shielding properties, and washing durability of the treated nonwoven polypropylene were also studied. It was found that Ag was uniformly deposited on the surface of the nonwoven polypropylene, and the coating reaction did not change the chemical structure of the polypropylene. The crystallinity and thermal stability of polypropylene were improved after silver coated polypropylene. The washing experiment results showed that the weight gain rate of the treated nonwoven relative to the untreated sample after the 90 min washing ranged from 6.72% to 9.64%. The resistance test results showed that the maximum surface resistivity of Ag coated nonwoven polypropylene was about 1.95 × 105 Ω, which was 64,615 times lower than the original. In addition, the results showed that the maximum electromagnetic shielding effectiveness of the Ag coated nonwoven polypropylene was about 71.6 dB, showing a very good electromagnetic shielding effect.

Structure and Properties of Polypropylene/Polyolefin Elastomer/Organic Montmorillonite Nanocomposites

The crystallinity, mechanical properties, and thermal stability of polypropylene (PP)/organic montmorillonite (OMMT) and PP/polyolefin elastomer (POE)/OMMT composites, with polypropylene-g-maleic anhydride/styrene (PPMS) as a compatibilizer for both, were compared. The results showed that the strong interaction between the clay platelets and compatibilizer, which were generated by the maleic anhydride (MAH), improved the compatibility of the polymer matrices with the OMMT. A unique lamellar, flocculated structure of OMMT was formed after introduction of the POE. The highly dispersed clay layers could act as nucleating agents, resulting in smaller spherulites and higher crystallization temperatures. Compared with pure PP, the PP/OMMT nanocomposite showed enhanced mechanical properties and thermal stability; however, the PP/POE/OMMT had the best impact toughness.

Thermal degradation kinetics of PP/PLA nanocomposite blends

In this article, the effect of adding polylactide (PLA) and nanoclay on the thermal stability of polypropylene (PP) films was analyzed using thermogravimetric analysis. The thermal degradation kinetic parameters such as activation energy ( Ea), order of reaction ( n), and frequency factor (ln ( Z)) of the samples were studied over a temperature range of 30–550°C. Analyses were performed under nitrogen atmosphere with four different heating rates (i.e. 5, 10, 15, and 20°C min−1). The Ea was calculated by Kissinger, Kim–Park, and Flynn–Wall methods. The Ea value of PP was much higher than PLA, whereas the addition of PLA and nanoclay in PP decreased the Ea. The addition of compatibilizer increased the compatibility and Ea of blended films upto some extent. The lifetime of PP was found to be decreased with the addition of PLA and nanoclay. Studies indicated that the thermal degradation behavior and lifetime of the investigated samples depend on the fractions of constituents and heating rates.

Improvement of flame retardancy and thermal stability of polypropylene by P-type hydrated silica aluminate containing lanthanum

Raw kaolinite (kaol) was experimentally transformed to P-type hydrated silica aluminate (HSA-P). After treated by LaCl3·7H2O solution, the final product of La-loaded for P-type hydrated silica aluminate (HSA-P-La) was obtained. The middle and final products were characterized using fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM). Kaol, HSA-P, HSA-P-La was introduced into PP with intumescent flame retardants (IFR), respectively. And their effect on the flame retardant and thermal properties of PP composites was studied by limiting oxygen index (LOI), vertical burning test, cone calorimeter test (CCT) and thermogravimetric analysis (TGA). The LOI increases from 18.0% of neat PP to 31.2 in composite of 75 wt% PP/25 wt % IFR, further increases to 32.5, 35.1, 37.5 in 75 wt% PP/23.5 wt % IFR/1.5 wt% Kaol, HSA-P or HSA-P-La, respectively. CCT results show heat release content and rate is best controlled in PP/IFR/HSA-P-La composite. Morphology observation indicates the char layer of PP/IFR/HSA-P-La composite is most compact and thick, which guarantees excellent fire resistance. At same time the effect of HSA-P/HSA-P-La was also compared with generally used A-type hydrated silica aluminate (HSA-A)/HSA-A-La. Anyway HSA-P/HSA-P-La exhibited higher efficiency than HSA-A/HSA-A-La in both flame retardancy and thermostability.

Enhanced wettability and thermal stability of nano-SiO2/poly(vinyl alcohol)-coated polypropylene composite separators for lithium-ion batteries

To improve the electrolyte wettability and thermal stability of polypropylene (PP) separators, nano-SiO2/poly(vinyl alcohol)-coated PP composite separators were prepared using a simple but efficient sol–gel and dip-coating method. The effects of the tetraethoxysilane (TEOS) dosage on the morphology, wettability, and thermal stability of the composite separators were investigated using Fourier-transform infrared spectroscopy, scanning electron microscopy, and contact-angle measurements. All the composite separators gave a smaller contact angle, higher electrolyte uptake, and lower thermal shrinkage compared with the PP separator, indicating enhanced wettability and thermal stability. Unlike the case for a traditional physical mixture, SiOC covalent bonds were formed in the coating layer. The composite separator with a TEOS dosage of 7.5wt% had a unique porous structure combining hierarchical pores with interstitial voids, and gave the best wettability and thermal stability. The ionic conductivity of the composite separator containing 7.5wt% TEOS was 1.26mS/cm, which is much higher than that of the PP separator (0.74mS/cm). The C-rate and cycling performances of batteries assembled with the composite separator containing 7.5wt% TEOS were better than those of batteries containing PP separators.

Layered Double Hydroxide Nanoplatelets with Ultrahigh Specific Surface Area for Significantly Enhanced Crystallization Rate and Thermal Stability of Polypropylene

A facile method for the simultaneous delamination and the lateral size reduction of layered double hydroxides (LDH) is reported. This method directly resulted in the delaminated mesoporous LDH nanoplatelets (nanodot LDH) with the high specific surface area (lateral dimensions as low as 10–30 nm and featured a thickness of ∼1 nm). Such prepared LDH was used as fillers for isotactic polypropylene (iPP). For the purpose of comparison, LDH having different surface areas were also used as fillers for iPP. The incorporation of nanodot LDH showed a remarkable improvement in the polymer properties with only 1 wt % loading. The uniformly dispersed LDH particles have a significant effect on the nucleation ability, thermal stability, and mechanical properties of iPP. The nucleation ability of iPP in the presence of nanodot LDH is the best compared to other iPP nanocomposites reported using LDH as fillers in the literature. Furthermore, the microstructure of the iPP nanocomposites was systematically investigated at m...

Investigation on γ-irradiated PP/ethylene acrylic elastomer TPVs by rheological and thermal approaches

Polypropylene (PP) was melt blended with varying concentration of ethylene acrylic elastomer (AEM) in a twin screw extruder and then γ-irradiated at several radiation doses to achieve a series of thermoplastic vulcanizates (TPV). The effect of AEM concentration and γ-irradiation on flow characteristics, crystallization and thermal degradation of blends were explained using melt dynamic rheology, differential scanning calorimetry and thermogravimetric analysis. Gel content values and dynamic rheological data of PP and AEM at different radiation doses confirmed the incessant scissioning of PP chains with radiation doses except for highest radiation dose, where crosslinking of PP chains took place and the incessant crosslinking of AEM chains irrespective of radiation doses. Oxidative degradation of PP was confirmed by FTIR spectroscopy, which also exhibited absence of any chemical interaction between two constituent polymers. Normalized crystallinity and melting point of compositions, obtained from DSC, decreased with the radiation doses. Furthermore, with the radiation doses clear shifts of maxima of the melting peak towards the lower temperature were observed for neat PP and blends. Thermal stability of PP and blends, as observed by TGA, reduced significantly with irradiation; whereas for AEM, no discernable change was observed. Enhanced chain scissioning of PP in presence of AEM reduced the thermal stability of blends, especially at lower irradiation. This reduction of thermal stability was established by “rule of mixture”, applied to the activation energy of thermal degradation. Thus, optimization of radiation doses to prepare TPVs was established.

Fabrication and characterization of olive pomace filled PP composites

The aim of this study is to investigate the filling properties of an agricultural waste, olive pomace powder (OP), for polypropylene (PP) matrix material. Different weight fractions of OP (from 10 to 40 wt %), which has a median particle size of 21.36 μm (D50) μm, were loaded into PP by high-speed thermo kinetic mixer. In this research, the effects of weight fraction of OP within PP on mechanical, viscoelastic, thermal, chemical, crystallographic, and morphological properties of PP composites were investigated by tensile and three point bending test, dynamic mechanic analysis, thermogravimetric analysis and differential scanning calorimetry, Fourier transform infrared analysis, X-ray diffraction analysis, and scanning electron microscopy. When 40 wt% OP filler was loaded into PP, the Young's modulus and flexural modulus of PP increased by about 62.5% and 19%, respectively. The storage modulus and thermal stability of PP were remarkably enhanced with increasing OP weight fraction.