Low‐temperature synthesis of Mg(OH)2 nanoparticles from MgO as halogen‐free flame retardant for polypropylene

Mg(OH)₂ (MH) nanoparticles were synthesized by hydration of the light‐burned MgO at low temperature (70°C). Effects of additives, such as magnesium nitrate and magnesium acetate, on the size, morphology and agglomeration of MH particles were investigated. MH nanoparticles have platelet‐like structure and approximately 20–40 nm in thicknesses. The supersaturation degree plays an important role in magnesia hydration and is defined. When magnesium acetate was used as the additive, the hydroxyl ion can be homogeneously introduced into the solution. The size and morphology of MH nanoparticles are more homogeneous. Modified by titanate coupling agent, MH nanoparticles were used as the flame retardant for polypropylene (PP). The combustibility, mechanical properties and thermal behaviors of the PP/MH composites were characterized. The mechanical properties of PP/MH composites are not seriously deteriorated with increasing MH content. When the amount of MH fraction reached 65, the limiting oxygen index (LOI) value and UL 94 testing result of MH65 are 33.8 and V‐0 grading, respectively. The onset temperature (T_10%) and the maximum thermal decomposition temperature (T_max) of MH65 separately increased by approximately 100°C and 77°C than those of neat PP. Copyright © 2012 John Wiley & Sons, Ltd.     

Kinetic thermal behavior of nanocellulose filled polylactic acid filament for fused filament fabrication 3D printing

Fused filament fabrication (FFF) with thermoplastic filaments is the most popular 3D printing technology. The continuous polymer filaments undergo a series of thermal processes, including heating, melting, cooling, and solidification. Therefore, it is necessary to investigate the thermal behavior of polymer filaments. The present study aims to provide a fundamental study of the thermal decomposition behavior and the isothermal melting crystallization behavior of nanocellulose filled polylactic acid (PLA) filaments. The influences of nanocellulose contents on the thermal decomposition properties such as onset temperature (137_onset), the temperature at 20-wt % conversion (T_α20), and the temperature at the peak decomposition rate (T_p) were examined by thermogravimetric analysis (TGA). The effects of nanocellulose contents on the glass transition temperature (T_g) and the melting temperature (T_m) were studied by differential scanning calorimetry (DSC). Effects of nanocellulose and polyethylene glycol (PEG) incorporation on the thermal decomposition activation energy, isothermal melting crystallization rate, and semi-crystallization time are also investigated. The addition of nanocellulose improves the thermal stability of PLA filament, whereas the addition of plasticizer PEG decreases the thermal stability. TGA and DSC kinetic analyses indicate that nanocellulose alone or together with PEG could drastically increase the crystallization rate and shorten the semi-crystallization time. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48374.     

Properties of flat‐pressed wood plastic composites containing fire retardants

This study investigated physical, mechanical, and fire properties of the flat‐pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) [5 or 15% by weight (wt)] at 50 wt % of the wood flour (WF). The WPC panels were made from dry‐blended WF, polypropylene (PP) with maleic anhydride‐grafted PP (2 wt %), and FR powder formulations using a conventional flat‐pressing process under laboratory conditions. The water resistance and strength values of the WPC panels were negatively affected by increasing the FR content as compared to the WPC panels without FR. The WPC panels incorporated with zinc borate (ZB) gave an overall best performance in both water resistance and strength values followed by the panels containing magnesium hydroxide (MH) and ammonium polyphosphate (APP). For these three FR's, the best fire resistance as measured in the cone calorimeter was obtained with the 15 wt % APP treatment and then followed by 15 wt % ZB, or 15 wt % MH formulations. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of high loaded wood flour and coupling agent (m-TMI-g-PP) content on properties of wood flour/polypropylene

The effects of wood flour content (60–80%) and m-TMI-g-PP content (0–14%) on the properties of wood flour/polypropylene composites (WF/PP) were investigated by means of mechanical properties, thermal analysis, dynamic rheological analysis, and scanning electron microscopy (SEM). The results demonstrated that WF significantly increased the mechanical properties, char yield, heat deflection temperature (HDT), vicat softening temperature (VST), T _c, G′, G″, and η ^?. However, WF above 70% led to decreased mechanical properties, so for the comprehensive consideration of the cost and environmental issues, 70% WF is the best. With the addition of m-TMI-g-PP, the mechanical properties, thermal stability, HDT, VST, △H _m, and T _m of composites were all got improvement, which was attributed to the strong interfacial interaction of m-TMI-g-PP on composites. However, when it exceeded 10%, the mechanical properties of the composites declined, it probably formed a separate phase in the PP matrix. Therefore, the 10% m-TMI-g-PP was chosen in WF/PP. In addition, the results were all further confirmed by SEM analysis.     

Kinetics of thermo-oxidative degradation of zinc borate/microcapsulated red phosphorus with magnesium hydroxide in flame retarded polypropylene composites

The flammability and the thermo-oxidative degradation kinetics of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with magnesium hydroxide (MH) in flame-retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), TGA, and FTIR spectroscopy. The results show that ZB/MRP is a good synergist for improving the flame retardancy of the PP composites. The Kissinger and Flynn-Wall-Ozawa methods were used to determine the activation energy (E) for degradation of PP composites. The results from the TGA curves indicate that the thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites is better than that of PP/MH composites. The kinetic results show that the values of E for degradation of PP/MH/ZB/MRP composites is much higher than those of PP/MH and PP/MH/ZB composites. The FTIR spectra data show that the incorporation of MH improves the thermo-oxidative stability of PP, especially for PP/MH composites with suitable content of MRP at higher temperatures. These data indicate that the synergistic flame retardants used in this work have a great effect on the mechanisms of pyrolysis and combustion of PP/MH composites.     

Thermal decomposition behavior of γ‐irradiated poly(vinyl acetate)/poly(methyl methacrylate) miscible blends

Miscible polymer blends based on various ratios of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were prepared in film form by the solution casting technique using benzene as a common solvent. The thermal decomposition behavior of these blends and their individual homopolymers before and after γ‐irradiation at various doses (50–250 kGy) was investigated. The thermogravimetric analysis technique was utilized to determine the temperatures at which the maximum value of the rate of reaction (T_max) occurs and the kinetic parameters of the thermal decomposition. The rate of reaction curves of the individual homopolymers or their blends before or after γ‐ irradiation displayed similar trends in which the T_max corresponding to all polymers was found to exist in the same position but with different values. These findings and the visual observations of the blend solutions and the transparency of the films gave support to the complete miscibility of these blends. Three transitions were observed along the reaction rate versus temperature curves; the first was around 100–200°C with no defined T_max, which may arise from the evaporation of the solvent. The second T_max was in the 340–380°C range, which depended on the polymer blend and the γ‐irradiation condition. A third transition was seen in the rate of reaction curves only for pure PVAc and its blends with PMMA with ratios up to 50%, regardless of γ‐ irradiation. We concluded that γ‐irradiation improved the thermal stability of PVAc/PMMA blends, even though the PMMA polymer was degradable by γ irradiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1773–1780, 2006     

Thermal degradation study of interpenetrating polymer network based on modified bismaleimide resin and cyanate ester

Interpenetrating polymer networks (IPNs) based on different ratios of a modified bismaleimide resin (BMI/DBA) and cyanate ester (b10) have been synthesized via prepolymerization followed by thermal curing. A systematic thermal degradation study of these new BMI/DBA‐CE IPN resin systems was conducted by thermogravimetric analysis at different heating rates both in N₂ (thermal stability) and in air (thermal‐oxidative stability). The cured BMI/DBA‐CE IPN resin systems show excellent thermal stability, which could be demonstrated by 5% weight loss temperature (T_5%) ranging between 409 and 423 °C, maximum decomposition rate temperature (T_max) ranging between 423 and 451 °C, and the char yields at 800 °C ranging from 37% to 41% in nitrogen at a heating rate of 10 °C min^?1. The apparent activation energy associated with the main degradation stage of the cured BMI/DBA‐CE IPN resin systems was determined using the Kissinger method. The obtained results provide useful information in drawing correlation between thermal properties and structure. © 2003 Society of Chemical Industry     

Preparation and characterization of wood-fiber-reinforced polyamide 6–polypropylene blend composites

In this study, we used lithium chloride (LiCl) as a modifier to decrease the melting temperature (T _m) of polyamide 6 (PA6), and then, we fabricated wood-fiber-reinforced PA6–polypropylene (PP) blend composites via hot pressing. From crystallization analysis, the composites exhibited a lower T _m and a lower processing temperature compared to PA6. Color and Fourier transform infrared analyses showed that severe thermal degradation and discoloration of the composites could be prevented by the incorporation of LiCl. LiCl had positive effects on the mechanical properties of the final product and the interfacial compatibility among PA6, PP, and wood fiber. The flexural strength increased by 8.5%. In addition, both maleic anhydride grafted PP and wood fiber improved the mechanical properties. The flexural strengths increased by 7.9 and 40%, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47413.     

Optimum compatibilization for the nonflammability of thermoplasticized crosslinked polyethylene/metal hydroxides composites with a compatibilizer

Nonflammability of the thermoplasticized crosslinked polyethylene (PE)/polyolefin elastomer (POE)/metal hydroxide flame retardant/compatibilizer composites were investigated. The thermoplasticized crosslinked PE was decrosslinked from the crosslinked high‐density PE under the supercritical methanol condition. Two types of metal hydroxides: aluminum hydroxide (AH) and magnesium hydroxide (MH), and a low‐density polyethylene‐g‐maleic anhydride (LM) were used as flame retardants and a compatibilizer, respectively. Nonflammability of both PE/POE/AH/LM and PE/POE/MH/LM composites was enhanced with metal hydroxide flame retardant concentration. PE/POE/MH/LM composites had better nonflammability than PE/POE/AH/LM composites at the same flame retardant concentration. Interestingly, nonflammability of the composites was also strongly influenced by the compatibilizer concentration. At low compatibilizer concentration, the nonflammability of the PE/POE/MH/LM composites was improved with the compatibilizer concentration. In contrast, at high compatibilizer concentration, the nonflammability of the PE/POE/MH/LM composites was deteriorated with the compatibilizer concentration. This demonstrates that optimum concentration of the compatibilizer can help to enhance the efficiency of the flame retardants in the development of the nonflammable polyolefin for the wire and cable industry. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of Wood Flour Content on the Thermal,Mechanical and Dielectric Properties of Poly(vinyl chloride)

Several composite formulations of poly(vinyl chloride)/olive wood flour (PVC/WF) were manufactured by dry‐blending PVC, wood flour, plasticizer and other processing additives in a high‐intensity mixer. The dry‐blended compounds were calendered into film samples (T = 180°C, calendered time = 8 min). The films obtained are cut into normalized samples for thermal, mechanical, and dielectric characterization. The results obtained show that stress as well as strain at break decrease sharply as the wood flour content increases. On the other hand, this filler content has little influence on the glass transition temperature. It decreases the temperature of decomposition setting and retards the PVC thermal decomposition. It increases permittivity as well as dielectric losses. The thermal stability, as measured by thermogravimetry (TGA) and differential scanning calorimetry (DSC) methods, is good enough to permit processing of these types of PVC compounds using conventional processing techniques and temperatures under 210°C.     

The effect of compatibilizers and organically modified nanoclay on the morphology and performance properties of poly(acrylonitrile–butadiene–styrene)/polypropylene blends

In this study, poly(acrylonitrile–butadiene–styrene)/polypropylene (ABS/PP) blends with various compositions were prepared by melt intercalation in a twin‐screw extruder. Modifications of the above blends were performed by using organically modified montmorillonite (OMMT, Cloisite 30B) reinforcement as well as two types of compatibilizers, namely polypropylene grafted with maleic anhydride (PP‐g‐MAH) and ABS grafted with maleic anhydride (ABS‐g‐MAH). Increasing the PP content in ABS matrix seems to increase the melt flow and thermal stability of their blends, whereas a deterioration of the tensile properties was recorded. On the other hand, the addition of ABS to PP promotes the formation of the β‐crystalline phase, which became maximum at 30 wt% ABS concentration, and increases the crystallization temperature (T_c) of PP. A tendency for increase of T_c was also recorded by incorporation of the above compatibilizers, whereas the glass transition temperature (T_g) of PP and SAN phase in ABS was reduced. Regarding the Young's modulus, the greatest improvement was observed in pure ABS/PP blends containing organically modified nanoclay. However, in reinforced pure PP, the use of compatibilizers is recommended in order to improve the elastic modulus. The addition of OMMT to noncompatibilized and compatibilized ABS/PP blends significantly improves their storage modulus. POLYM. ENG. SCI., 56:458–468, 2016. © 2016 Society of Plastics Engineers     

Mechanical properties,flame retardancy,hot‐air ageing,and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber/hydrogenated nitrile‐butadiene rubber/magnesium hydroxide composites

The mechanical properties, flame retardancy, hot‐air ageing, and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber (EVM)/hydrogenated nitrile‐butadiene rubber (HNBR)/magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/MH composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot‐air ageing resistance and hot‐oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (T_g) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot‐oil ageing, and hot‐air ageing resistance combined with good mechanical properties performance in a wide temperature range (?30°C to 150°C) make the EVM/HNBR/MH composites ideal for cables application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polypropylene/natural rubber composites filled with recycled newspaper: Effect of chemical treatment using maleic anhydride‐grafted polypropylene and 3‐aminopropyltriethoxysilane

A study on effect of chemical treatment using maleic anhydride‐grafted polypropylene (MAPP) and 3‐aminopropyltiethoxysilane (3‐APE) was investigated. The performance of the MAPP and 3‐APE were investigated by means of torque development, mechanical properties, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy morphology, and water absorption. The results revealed that the use of MAPP or 3‐APE in the composites has increased the stabilization torque, tensile strength, Young's modulus, water absorption, and thermal stability of the PP/NR composites. The incorporation of MAPP in the composites shows higher stabilization torque, tensile strength, E_B, Young's modulus, and lower water uptake when compared with the use of 3‐APE in the PP/NR composites. TGA and DSC results indicated that primary and secondary peak of DTG curve, initial degradation temperature (T₀), degradation temperature (T_deg), melting temperature (T_m), heat of fusion of composites (ΔH_f(com)), crystallinity of composites (X_PP), and PP (X_PP) increased, while total weight loss and thermal degradation rate decreased for both treated composites. The MAPP‐treated RNP‐filled PP/NR composites were found to be more thermal resistance and more crystalline than 3‐APE‐treated filled PP/NR RNP composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Characterisation of thermally treated and untreated polyethylene–polypropylene blends using DSC,TGA and IR techniques

Abstract

The thermal characteristics of thermally treated and untreated very low density polyethylene, isotactic polypropylene and their blends were investigated. Injection moulded blends containing five different weight percentages of VLDPE/iPP were prepared and thermally treated at 100°C for 2, 4, 7 and 14 days. Differential scanning calorimetry, thermogravimetry and infrared spectral analysis techniques were used to study the effect of thermal treatment and blending ratio on the thermal and chemical stability. The addition of PE had caused the T _m, heat of fusion and percentage crystallinity of PP main melting peak to decrease, indicating that both polymers are partially miscible. T _m has been found to increase with aging time, however, the heat of fusion is not significantly affected. The initial and final decomposition temperatures, maximum decomposition rate temperature, order of decomposition reaction, activation energy and activation enthalpy were calculated, in a dynamic nitrogen atmosphere, and discussed in terms of blending ratios and aging times. The IR spectra of all blends at different aging times do not show any degradation products.     

Particular thermal properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers

Telechelic hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s (PHBV-diols) were synthesized by transesterification with ethylene glycol, which could be used as the macromonomers for synthesis of block copolymers. PHBV-diols owned particular thermal properties. PHBV-diols had much lower the melting temperatures (T _m s) and better thermal stability than original PHBV. With the decrease of molecular weight, T _m s of PHBV-diols decreased gradually and maximum degradation temperatures (T _max s) increased gradually. T _max -T _m of PHBV-diol could increase by 57.9 °C in comparison with original PHBV. It was meaningful that PHBV block in the block copolymers based on PHBV-diol owned the good thermal stability and low melting temperature of its precursor PHBV-diol, which widened greatly the melt-processing window of PHBV. In addition, thermal degradation kinetics was studied by Ozawa method, the integration method and Kissinger method. The results showed that the thermal degradation of original PHBV and PHBV-diols proceeded by at least two steps including a random degradation process and subsequent thermal degradation process due to the auto-accelerated degradation reaction.     

Novel biodegradable flame retardant,poly(butyl methacrylate)/sodium silicate/Mg(OH)2 nanocomposite

Flame retardant poly(butyl methacrylate)/sodium silicate/Mg(OH)₂ (MH) nanocomposite has been prepared via in situ emulsion polymerization of BMA, benzoyl peroxide, layered silicate, and conventional fire retardant additive, MH. The morphology, thermal stability, and flammability properties of the nanocomposite were characterized by IR, XRD, TEM, TGA, cone calorimetry, and limiting oxygen index. The thermal stability and the flame retardant properties of the polymer‐silicate‐MH showed significant improvements in the decomposition temperature and the lower heat release rates due to the formation of nanocomposites with layered silicates. Biodegradation testing by Bacillus cereus (gram‐positive) revealed the ecofriendly nature of the nanocomposite. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

The influence of filler treatment on the properties of TPU/PP blends: I. Thermal properties and stability

Commercially available organosilane (3‐glycidoxypropyltrimethoxysilane (GPTMS)) coupling agent was used to treat talc in order to improve the affinity relative between the filler and the polymer in composites as well as filler and polymer in the thermoplastic polyurethane/polypropylene (TPU/PP) blends (talc content was 5 wt%). The talc particles were first modified with GPTMS and then introduced into TPU, PP as well as TPU/PP blends with different weight ratios of polymers using blending method and subsequently injection molded in a hydraulic press. The aim was to report the effect of silane coupling agent on the thermal and morphological properties of talc filled composites and blends. The results showed that the thermal properties of the TPU, PP composites and TPU/PP blends were improved with the addition of silane treated talc (higher melting (T_m), crystallization (T_c) temperatures and degree of crystallinity (χ_c)). The glass transition temperature (T_g) obtained by dynamic mechanical analysis (DMA) of the TPU soft segments in TPU/PP blends increased with the addition of untreated and silane treated talc due to lower mobility of the soft segments in TPU and better miscibility of TPU and PP. TPU/PP blends with the silane treated talc show better thermal stability than the TPU/PP blends with untreated talc. POLYM. ENG. SCI., 55:1920–1930, 2015. © 2014 Society of Plastics Engineers     

Synthesis and properties of polypropylene/layered double hydroxide nanocomposites with different LDHs particle sizes

In order to investigate whether the particle sizes of inorganic additives in polymer have an influence on the flame‐retardant and other properties of the polymer, five types of Mg₃Al–CO₃ layered double hydroxide (LDHs) with particle diameters of 80–100, 200–350, 500–550, 550–600, and 700–900 nm were synthesized using a hydrothermal method. The obtained Mg₃Al–CO₃ LDHs were treated using the aqueous miscible organic solvent treatment method to give highly dispersed platelets in Polypropylene (PP). The thermal stability, flame retardancy, and mechanical properties of the PP/AMO–LDH nanocomposites were investigated systematically. The results showed that the thermal stability and flame retardancy of PP could be improved after incorporating AMO–LDHs. The temperature at 50% weight loss (T_0.5) of PP/LDH (700–900 nm) nanocomposites with a LDH loading of 15 wt % was increased by 57 °C. When the LDHs loading was 40 wt %, the peak heat release rate (PHRR) of the PP/LDH nanocomposites with small LDHs particle sizes (<350 nm) was decreased by ca. 58%. The limiting oxygen index was increased by 5% for PP/LDH (80–100 nm) nanocomposites. The response surface regression results also indicated that both LDH particle size and loading have influence on PHRR, heat release capacity, tensile strength, and elongation at break. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46204.     

Thermal and mechanical properties of electron beam irradiated poly(vinyl chloride)/polystyrene blends

The effect of electron beam irradiation on the thermal and mechanical properties of poly(vinyl chloride)/polystyrene (PVC/PS) blends and PVC/PS blends containing epoxidized natural rubber (ENR) was studied. The thermogravimetric analysis study showed that the thermal decomposition of the plasticized PVC individual polymer goes through two stages, whereas PS decomposes through one stage. However, the temperature of the maximum rate of reaction (T_max) of PS is much higher than that for PVC and their blends. Meanwhile, the T_max was found to increase with increasing PS ratios in the blend. The thermal stability of PVC/PS blends was greatly increased after electron beam irradiation in comparison with unirradiated blends. Moreover, the addition of ENR to PVC/PS increased the thermal stability. On the other hand, the mechanical properties in terms of tensile strength and elongation at break of PVC/PS blends are lower than pure PVC polymer because of the immiscibility. However, the addition of ENR to the PVC/PS (80/20) blend increased the elongation at break from 114 to 321% associated with a small effect on the tensile properties. These behaviors were supported by structure morphology studies observations, which indicate an improvement in the interfacial adhesion between the phases. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

The influence of the compatibilizer on the morphology and thermal properties of polypropylene‐layered double hydroxide composites

Polypropylene (PP)/layered double hydroxide (LDH) composites were prepared via melt‐compounding using both a carbonate‐LDH and an organo‐LDH (dodecyl benzene sulfonate DBS‐LDH) in different concentrations. Transmission electron microscopy and X‐ray diffraction analysis were used to investigate the morphology. The results showed that only by using DBS‐LDH the intercalation of polymer chains and a partial delamination were obtained. However, the introduction of maleic anhydride‐grafted polypropylene (PP‐g‐MAH), as coupling agent, favored the aggregation of the particles generating localized domains of aggregates. The thermo‐gravimetric analysis showed that PP/DBS‐LDH composites have a higher thermal stability than the pure matrix. Differential scanning calorimetry evidenced that both LDH and DBS‐LDH particles acted as nucleating agents increasing the crystallization temperature, even if, in the case of LDH the effect was observed only with the addition of the compatibilizer. The results collected by dynamic mechanical thermal analysis, beyond showing a significant increase of the matrix stiffness by incorporation of DBS‐LDH, evidenced an increase of the PP glass transition temperature (T_g) indicating a restriction of PP chain segment mobility due to the strong polymer‐particle interactions. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers