Properties of polypropylene/aluminum trihydroxide composites containing nanosized organoclay

Montmorillonite is a promising substitute for aluminum trihydroxide in flame‐retardant polypropylene/aluminum trihydroxide (PP/ATH) composites. Study was made of the partial substitution of organoclay for ATH in PP/ATH composites. The total concentration of filler was kept at 30 wt%. The composites were compatibilized with two types of compatibilizer: commercial maleic anhydride functionalized polypropylene (PP‐g‐MA) and hydroxyl‐functionalized polypropylene (PP‐co‐OH) prepared with metallocene catalyst. The effect of compatibilization on the morphology was studied by the transmission electron microscopy and the scanning electron microscopy. Mechanical properties were characterized by tensile and impact measurements, and flammability properties with a cone calorimeter. Addition of compatibilizer and stearic acid (SA) treatment of the ATH particles contributed to the dispersion of the fillers. Both compatibilizers produced organoclay with exfoliated structure and improved adhesion between the fillers and the matrix. Toughness improved and decomposition and flammability were reduced. POLYM. ENG. SCI. 45:1568–1575, 2005. © 2005 Society of Plastics Engineers     

Influence of incorporation methods of ATH on microstructure,elastomeric properties,flammability, and thermal decomposition of dynamically vulcanized NR/PP blends

Flame‐retardant thermoplastic vulcanizates (TPVs) of natural rubber (NR)/polypropylene (PP) (60/40 wt %) blends filled with alumina trihydrate (ATH) were prepared with an internal mixer. To increase the properties of flame‐retardant NR/PP TPV, the new mixing method, stepwise masterbatch mixing (SMB) method was adopted. The effects of SMB method along with different ATH loadings on microstructure and properties of NR/PP TPVs were investigated. Conventional one‐step mixing (CV) method was also studied for comparison. Transmission electron microscopy analysis showed that different processes led to a variation in microstructural homogeneity, which imposed various effects on blend properties. The mechanical properties of TPVs changed with ATH loading, and the strength of the samples obtained from SMB method was higher than those of CV method. LOI and cone calorimetry tests revealed that the flame retardancy of NR/PP blends dramatically increased at higher ATH loading. Furthermore, the increment level of flame retardancy was accelerated in the blends produced particularly through SMB method, resulting from homogeneity of local ATH distribution in NR/PP blend. Greater combustion resistance of blends prepared from SMB route were confirmed by thermogravimetry and pyrolysis‐gas chromatography–mass spectrometry techniques. Finally, a burning mechanism between filler structure and flammability of NR/PP TPVs obtained from CV and SMB methods was discussed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46231.     

Electrical and flammability properties of alumina trihydrate filled polypropylene/ethylene propylene diene monomer composites as insulators in cable applications

Polymeric insulators role in power systems and insulation is one of the most important subjects in high voltage applications. This study investigates the effect of alumina trihydrate (ATH) loading on electrical and flammability properties of polypropylene (PP)/ethylene propylene diene monomer (EPDM) blend. ATH fillers were incorporated into the matrix to improve the tracking and flammability resistance of the composites. PP/EPDM (60:40) was used as matrix and compounding of ATH filled PP/EPDM composites was done using a twin‐screw extruder. Electrical and flammability tests of composites were performed. The results show that flammability decreased with increasing ATH loading in PP/EPDM composites. The effects of electrical stresses are investigated by measuring the carbon tracking (CT) and leakage current (LC) on the surface of composites. The CT and LC of PP/EPDM/ATH composites were found to decrease with increasing ATH content; however calculating the normalized degradation index (NDI) illustrated that all the sample were in accepted range. Field emission scanning electron microscope was used to relate the electrical properties with the morphological analysis, which showed that addition of ATH prevents the degradation of the matrix. POLYM. ENG. SCI., 54:493–498, 2014. © 2013 Society of Plastics Engineers     

Influence of polyamide 6 as a charring agent on the flame retardancy,thermal, and mechanical properties of polypropylene composites

In this work, polyamide 6 (PA6) as a charring agent has been used in combination with thermoplastic polyurethane (TPU)‐microencapsulated ammonium polyphosphate (MTAPP) forming intumescent flame retardants (IFRs) which applies in polypropylene (PP). The effects of the IFRs on the flame retardancy, morphology of char layers, water resistance, thermal properties and mechanical properties of flame‐retardant PP composites are investigated by limiting oxygen index (LOI), UL‐94 test, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical properties test. The results show that the PP/MTAPP/PA6 composites exhibit much better flame‐retardant performances than the PP/MTAPP composites. The higher LOI values and UL‐94 V‐2 of the PP/MTAPP composites with suitable amount of PA6 are obtained, which is attributed to the thick and compact char layer structure evidenced by SEM. The results from TGA and DSC demonstrate that the introduction of PA6 into PP/MTAPP composites has a great effect on the thermal stability and crystallization behaviors of the composites. Furthermore, the mechanical properties of PP/MTAPP/PA6 composites are also improved greatly due to the presence of PA6 as a charring agent. POLYM. ENG. SCI., 55:1355–1360, 2015. © 2015 Society of Plastics Engineers     

Crystallization,melting behavior,and crystal structure of reactive,intumescent, flame‐retardant polypropylene

Polypropylene (PP)/2‐({9‐[(4,6‐diamino‐1,3,5‐triazin‐2‐yl) amino]‐3,9‐dioxido‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro [5.5] undecan‐3‐yl} oxy) ethyl methacrylate (EADP) composites were prepared by the blending of PP with EADP as a new flame‐retardant material. The nonisothermal crystallization and melting behaviors of composites were investigated with differential scanning calorimetry (DSC). Their crystal morphologies and structures were studied by polarized optical microscopy (POM) and X‐ray diffraction (XRD), respectively. The DSC results show that the addition of EADP increased the crystallization onset temperature, crystallization peak temperature, and degree of crystallinity of PP in the PP/EADP composites. The melting onset temperature and melting end temperature of the PP/EADP composites decreased slightly, whereas the melting peak temperature of the PP/EADP composites increased. The POM results show that the addition of EADP greatly reduced the crystal size of PP in the composites. When the content of EADP in the PP/EADP composites was increased, the crystal size of PP became smaller. The XRD results indicate that the addition of EADP changed the crystal structure of PP in the PP/EADP composites, which exhibited both α‐form and β‐form crystal structures. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41374.     

Polypropylene/date stone flour composites: Effects of filler contents and EBAGMA compatibilizer on morphology,thermal, and mechanical properties

This work aims to study the effects of date stone flour (DSF) on morphology, thermal, and mechanical properties of polypropylene (PP) composites in the absence and presence of ethylene‐butyl acrylate‐glycidyl methacrylate (EBAGMA) used as the compatibilizer. DSF was added to the PP matrix at loading rates of 10, 20, 30, and 40 wt %, while the amount of compatibilizer was fixed to the half of the filler content. The study showed through scanning electron microscopy analysis that EBAGMA compatibilizer improved the dispersion and the wettability of DSF in the PP matrix. Thermogravimetric analysis (TGA) indicated a slight decrease in the decomposition temperature at onset (T_onset) for all composite materials compared to PP matrix, whereas the thermal degradation rate was slower. Differential scanning calorimetry (DSC) data revealed that the melting temperature of PP in the composite materials remained almost unchanged. The nucleating effect of DSF was however reduced by the compatibilizer. Furthermore, the incorporation of DSF resulted in the increase of stiffness of the PP composites accompanied by a significant decrease in both the stress and strain at break. The addition of EBAGMA to PP/DSF composites improved significantly the ductility due to the elastomeric effect of EBAGMA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structural characterization of LDPE/EVA blends containing nanoclay‐flame retardant combinations

The combination of different types of organo‐modified montmorillonite (MMT) with aluminum hydroxide (aluminum trihydrate—ATH), as a flame retardant system for polyethylene‐ethylene vinyl acetate (LDPE/EVA), blends were studied. Five different types of organically modified montmorillonite clays, each with different modifier, were used. The structural characterization was carried out by X‐ray diffraction (XRD) and scanning electron microscopy in transmission mode (STEM). The mechanical and rheological properties were also evaluated. The XRD analysis showed a clear displacement of the d₀₀₁ signal, which indicates a good degree of intercalation, especially for the MMT‐I28 and MMT‐20, from Nanocor and Southern Clay Products, respectively. The presence of ATH and the compatibilizer did not have any effect on the exfoliation of the studied samples. The thermal stability and flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI—ASTM D2863), and flammability tests (Underwriters Laboratory—UL‐94). The effect of different compatibilizers on the clay dispersion and exfoliation was studied. The results indicated that the addition of montmorillonite makes it possible to substitute part of the ATH filler content while maintaining the flame retardant requirements. The thermal stability of MMT/ATH‐filled LDPE/EVA blends presented a slight increase over the reference ATH‐filled LDPE/EVA blend. Compositions with higher clay content (10 wt %) showed better physicochemical properties. The increased stability of the higher clay content compositions results from the greater inorganic residual formation; this material has been reported to impart better performance in flammability tests. The mechanical properties and flame retardancy remained similar to those of the reference compound. The reduced ATH content resulted in lower viscosities and densities, facilitating the processing of the polymer/ATH/clay compounds. Extrusion of these compounds produced a lower pressure in the extrusion head and required reduced electrical power consumption. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate grafted polypropylene on the interfacial interaction of wood‐flour/polypropylene composites

In this article, the effects of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate grafted polypropylene (m‐TMI‐PP) on the interfacial interaction of wood‐flour/polypropylene (WF/PP) were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry, dynamic rheological analysis, and mechanical properties tests. The experimental results demonstrated that m‐TMI‐PP greatly improved the interfacial interaction between WF and PP. According to the DSC results, m‐TMI‐PP made the crystallization temperature and the crystallization degree of PP in WF/m‐TMI‐PP/PP decrease when compared with WF/PP composite without m‐TMI‐PP, but it was still higher than pure PP. These results demonstrated that WF presented the nucleate effect for the crystallization of PP and m‐TMI‐PP improved the interfacial adhesive, which restrained the mobility of PP chain. The rheological analysis indicated that the complex viscosity, storage, and loss modular of WF/PP composite increased, and the tan δ decreased with the addition of m‐TMI‐PP. This was attributed to the strong improvement effects of m‐TMI‐PP on the interfacial interaction of the composites, and was further confirmed by the mechanical properties tests and SEM analysis of the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Co‐microencapsulation of ammonium polyphosphate and aluminum hydroxide in halogen‐free and intumescent flame retarding polypropylene

In this article, co‐microencapsulated ammonium polyphosphate (APP) and aluminum hydroxide (ATH) [M(A&A)] was prepared by using 4,4'‐diphenylmethane diisocyanate (MDI) and melamine (MEL) via in situ surface polymerization method. The chemical composition of M(A&A) was confirmed by Fourier transform‐infrared spectra (FT‐IR). Thermal behavior and surface morphology of M(A&A) were systematically analyzed by thermogravimetric analysis (TGA) and scanning electron microscope (SEM), respectively. Water solubility tests indicate that water solubility of M(A&A) decreases greatly than un‐microencapsulated ones. Besides, flame retardant properties of polypropylene (PP) compositing with M(A&A) were investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94) and cone calorimeter. The results demonstrate the LOI value of PP composites is improved after combining with co‐microencapsulated flame retardants. Compared with PP/A&A, the peak heat release rate of PP/M(A&A) decreases from 210 to 120 kW/m² at the same flame retardant loading level. Moreover, in order to investigate the flame retardant mechanism, the char residue of PP composites after combustion was studied by optical photos, X‐ray photoelectron spectroscopy (XPS) spectra and FT‐IR. POLYM. COMPOS., 35:715–729, 2014. © 2013 Society of Plastics Engineers     

Flame retardancy and toughening of high impact polystyrene

Flame retardant high impact polystyrene (HIPS) was prepared by melt blending HIPS, nano‐modified aluminum trihydrate (nano‐CG‐ATH), red phosphorus masterbatch (RPM), and modified polyphenylene oxide (MPPO). Styrene‐butadiene‐styrene (SBS) was used as a toughener in this research. The effects of nano‐CG‐ATH, RPM, MPPO, and SBS on properties of HIPS composites were studied by combustion test, mechanical tests, and thermogravimetric analysis. The morphologies of fracture surfaces and char layers were characterized through scanning electron microscopy (SEM). The HIPS/nano‐CG‐ATH/RPM/MPPO (60/6/9/25) composite and its combustion residues at various temperatures were characterized by Fourier transform infrared (FTIR) spectra analysis. The results showed that the UL‐94 rating of the HIPS/nano‐CG‐ATH/RPM/MPPO (60/6/9/25) composite reached V‐0 and its char layer after flame test was integrated, but its impact strength was low. Addition of SBS improved its impact property and did not influence its thermal and flame retardant properties but lowered its tensile strength and flexural modulus to some extent. The FTIR spectra confirmed that the P O C group was present in the charred substance. POLYM. COMPOS., 28:551–559, 2007. © 2007 Society of Plastics Engineers     

Study of effect of old corrugated cardboard in properties of polypropylene composites: Study of mechanical properties,thermal behavior,and morphological properties

The investigation of the economical use of lignocellulose waste, which is one of the environmental problems facing nations, is ongoing. In this study, waste cardboard paper fiber reinforcing polypropylene (PP) composites was developed. In order to modify the PP matrix maleated PP (MA‐g‐PP) a 5 wt% and a grafting rate of 1 and 2 wt% was used as a compatibilizer. The effects of fiber and compatibilizer content as well as graft content are evaluated by mechanical, thermal property measurements, and scanning electron microscopy (SEM). The compatibilizer improved all mechanical properties significantly. Thus, the tensile strength of MA‐g‐PP‐containing composites increases compared to PP/cardboard composites paper content increases. However, the tensile modulus of a PP‐based composite increases with an increase in paper fiber with the compatibilizer having little effect. SEM revealed that the addition of MA‐g‐PP generates strong interactions between a PP matrix and paper fibers. However, the addition of the MA‐g‐PP compatibilizing agent gives a significant improvement on the crystallization of the composites, whereas the compatibilized PP/old corrugated cardboard (OCC) composites have higher crystallinity (Xc) than uncompatibilized PP/OCC composites. The MA‐g‐PP also diminished the water absorption in the composites. J. VINYL ADDIT. TECHNOL., 22:231–238, 2016. © 2014 Society of Plastics Engineers     

Using PA6 as a charring agent in intumescent polypropylene formulations based on carboxylated polypropylene compatibilizer and nano‐montmorillonite synergistic agent

The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M = 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA‐6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6‐g‐EPP cocrystallized with PA6, and EPP‐g‐PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano‐montmorillonite (nano‐MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano‐MMT enhanced the mechanical strength by 44.3%. SEM showed that nano‐MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano‐MMT was an effective flame retardant in improving combustion properties of polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 739–746, 2006     

氢氧化铝无卤阻燃乙烯醋酸乙烯共聚物的结构与性能

以表面修饰的氢氧化铝（ATH）作为无卤阻燃剂,以线形低密度聚乙烯接枝物为相容剂制备了阻燃性能和力学性能优良的无卤阻燃乙烯醋酸乙烯（EVA）复合材料。通过扫描电子显微镜、力学性能测试、动态热力学分析、极限氧指数、垂直燃烧测试表征了AHT阻燃EVA复合材料的结构与性能。研究了表面处理及相容剂的引入对ATH在EVA中的分散性和界面相容性的影响,以及AHT粒径大小、添加量对EVA阻燃性能和力学性能的影响。结果表明,界面相容剂和表面处理剂同时使用,能显著提高ATH与基体之间的界面相容性,从而提高了EVA的力学性能和阻燃效果,ATH尺寸越小,阻燃性能越好。     

PET/PP blending by using PP‐g‐MA synthesized by solid phase

In attempts to improve the compatibility of polypropylene (PP) with polyethylene terephthalate (PET), a maleic anhydride grafted PP (PP‐g‐MA) was evaluated as a compatibilizer in a blend of 30/70 wt % PP/PET. PP‐g‐MA was produced from isotactic homopolymer PP utilizing the technique of solid phase graft copolymerization. Qualitative confirmations of the grafting were made by Fourier transform infrared spectroscopy (FTIR). Three different weight percent of compatibilizer, PP‐g‐MA, i.e., 5, 10, and 15 wt % have been used in PP/PET blends. The compatibilizing efficiency for PP/PET blend was examined using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM) of crycrofractured surfaces, and energy dispersive X‐ray spectrum (EDAX). The results show that the grafted PP promotes a fine dispersed phase morphology, improves processability, and modifies the crystallization behavior of the polyester component. These effects are attributed to enhance phase interaction resulting in reduced interfacial tension. Also, the results show that the compatibilizing effects of the three amounts of grafted PP in blend are different and dependent on the amount used. Adding 10 wt % of compatibilizer into blend produced the finest dispersed morphology. Elemental analysis results show that PP is matrix. DSC determination revealed that the melting temperature (T_m) of the PET component declined to some extent by comparison with neat PET. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3986–3993, 2007     

PP无卤阻燃复合材料性能研究

采用双辊塑炼机制备了不同组分的聚丙烯(PP)无卤阻燃复合材料。利用差示扫描量热仪(DSC)、偏光显微镜(POM)和扫描电子显微镜(SEM)研究了Mg(OH)2、乙烯-辛烯共聚物(POE)、相容剂PP-g-MAH对PP无卤阻燃复合材料的热行为、结晶形态和微观结构的影响。结果表明:Mg(OH)2和POE两种成核剂的异相成核作用提高了共混物中PP的结晶温度和结晶速率;Mg(OH)2的加入使球晶颗粒变得细小且有碎晶产生;POE大分子链使PP分子链的扩散和堆积受阻,阻碍了晶粒的生长,从而导致PP/Mg(OH)2/POE复合材料结晶度的降低。PP-g-MAH的加入可以提高PP与Mg(OH)2的界面相容性,当PP/Mg(OH)2/POE/PP-g-MAH的配比为80/100/20/2时,PP无卤阻燃复合材料可以同时拥有良好的力学性能和阻燃性能。     

The flame retardancy and mechanical properties of jute/polypropylene composites enhanced by ammonium polyphosphate/polypropylene powder

Surface flame retarded jute/polypropylene composites (J/P/A) were prepared via a modified strategy: the mixture of PP and APP powder was spread over the surface of jute/PP nonwoven felts, and then transformed into the flame retarded layer by the hot pressing process. The flame retardancy and thermal properties of composites were analyzed by limit oxygen index (LOI), horizontal burning rate (HBR), thermogravimetric analyses (TGA), and differential scanning calorimetry (DSC). We demonstrated that the flame retardancy and mechanical properties of composites was significantly improved compared with those obtained by presoaking the nonwoven fiber felts in flame retardant (FR) solvent before hot pressing. The mechanism of thermal degradation of jute fiber and flame‐retardant mechanism of composites were analyzed by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and scanning electron microscope (SEM). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43889.     

Viscoelastic,thermo-mechanical and environmental properties of composites based on polypropylene/poly(lactic acid) blend and copper modified nanoclay

Poly(lactic acid) (PLA)/polypropylene (PP) blends composites were prepared by incorporating 3 wt.% of copper modified montmorillonite (MMT-Cu²⁺), obtained using cation exchange in a CuSO₄ solution, and 10 wt.% of polypropylene-graft-maleic anhydride (PP-g-MA) as a compatibilizer then varying the PLA content until 50 wt.%. These materials were subjected to several investigations such as X-rays diffraction, dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile and environmental tests. The DMTA analysis showed that the glassy PLA high stiffness and the PP crystalline phase compensate the decrease in the storage modulus occurring during the PP and PLA glass transitions, respectively. The variations of tan δ revealed no changes on the PP and PLA phases glass transitions temperatures which indicate the immiscibility of the two polymers, as supported by DSC analysis. Blends composites SEM micrographs stated the immiscibility of the system resulting in the poor adhesion of the PLA droplets to the PP matrix. Also, the blends composites exhibited intermediate tensile properties between those of PP and PLA. The incorporation of MMT-Cu²⁺ to the (50/50) PP/PLA blend accentuated its aptitude to water absorption and ensured an efficient antimicrobial activity over a satisfactorily long period of around six months.     

Morphological structure and mechanical properties of In situ microfibrillar composites of modified PA66 with PP

In situ microfibrillar composites (PP/mPA66) of modified polyamide66 (mPA66) with polypropylene (PP) were prepared by using a “post‐compatibilization” technique. The mPA66 was firstly obtained by reactive extrusion of PA66 resin with a specially designed compatibilizer, which was then blended with PP through extrusion combined with a hot stretching and subsequently quenching process. The PP/mPA66 in situ microfibrillar composites were comparatively studied with simply blended samples of PP/PA66 that were prepared by blending PA66 and PP together with (or without) the same compatibilizer through extrusion. PA66‐g‐PP (and/or elastomers) graft copolymer formation in mPA66 was identified by dissolution test and infrared spectroscopy measurement, the compatibilizer is unevenly dispersed with large domains in PA66 as observed by scanning electron microscope (SEM). In PP/mPA66 composites, the in situ generated PA66 microfibrils have a rather nonuniform diameter distribution and a very rough surface. SEM observations for the fractured surface illustrated that PP/mPA66 composites have structural characteristics of stronger adhesion and moderate flexibility of the interface. Enhanced compatibilization between the PA66 microfibrils with the PP matrix resulted in improved mechanical properties of the PP/mPA66 composites. With optimized composition, the PP/mPA66 composite has notched Izod impact strength, flexural modulus, and tensile yield stress of 1.49, 1.16, and 0.99 times as those of the neat PP, respectively. Such enhanced mechanical properties balance and improved interface adhesion were not found in the simply blended samples of PP/PA66 with or without the specially designed compatibilizer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of fire retardants on mechanical properties of a green bio-epoxy composite

To improve fire retardant behavior of bio-epoxy resin, composites were prepared with three fire retardants (FRs); ammonium polyphosphate, aluminum trihydrate, and magnesium hydroxide. Fractured surfaces of prepared composites were observed with the scanning electron microscope (SEM). Tensile strength and Charpy toughness were evaluated and analyzed statistically using analysis of variance (ANOVA). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to determine the thermal stability. SEM analysis results revealed fractured surfaces were altered with addition of FRs. Adding FRs can be regarded as a decrease in tensile strength and toughness complemented by improved stiffness. ANOVA analysis showed FR/bio-resin composites have a statistically significant loss in tensile strength, stiffness, elongation, and Charpy toughness. The DSC results showed the glass transition temperature was not affected significantly by adding FRs and ranged from 66 to 69 °C. TGA showed the initial, midway, and maximum decomposition temperatures for composites and their ability to form improved ash yields compared to pure resin. Aluminum trihydrate and Mg(OH)₂ had higher T₅₀ suggesting an increase in thermal stability compared to pure bio-epoxy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47398.     

Fatigue life of coir fiber reinforced PP composites: Effect of compatibilizer and coir fiber contents

The fatigue behavior of polypropylene/coir fiber composites was investigated. Composites were prepared according to an experimental statistical design, in which the independent variables coir fiber and compatibilizer content were varied. The compatibilizer used was maleic anhydride grafted polypropylene (PP‐g‐MA). Compatibilizer free composites were also prepared. Composites were prepared in a corotating twin‐screw extruder and the mechanical behavior of polypropylene/coir fiber composites were assessed through monotonic (tensile) and cyclic (fatigue) tests. Fatigue load controlled tests were conducted under tension–tension loads at a frequency of 6 Hz. The fracture mechanism was accompanied by surface fracture analyses using scanning electron microscopy (SEM). The results indicated the need for using compatibilizer in the composites; however, increase in compatibilizer content did not affect composite fatigue lifetime. Coir content was the variable with the strongest effect on composite properties; increasing this variable caused significant increase in fatigue life. POLYM. ENG. SCI., 53:2159–2165, 2013. © 2013 Society of Plastics Engineers