Sub-micron scale mechanical properties of polypropylene fibers exposed to ultraviolet and thermal degradation

Nanoindentation using atomic force microscopy (AFM) was conducted to investigate the affect of accelerated ultraviolet (UV) and thermal degradation on the mechanical properties of polypropylene fibers. The affect of degradation on Young’s modulus across fiber cross-sections was investigated with progressive nanoindentation from the surface to the center of the fiber. UV degradation initially increases the Young’s modulus both at the center and the surface of the fibers until 120 h of exposure with the increase being more rapid at the surface. Moduli started to decrease beyond 120 h of exposure. Wide angle x-ray scattering shows an increase of crystallinity up to 120 h of exposure and total destruction of crystallinity at 144 h. Infrared spectra showed the formation of carbonyl bonds with UV exposure. To investigate thermal degradation, the fibers were exposed to 125 °C for four weeks. Young’s modulus increased near the surface after four weeks exposure. These results support the idea that surface degradation may lead to embrittlement of textile fibers.     

Thermal behaviour of compatibilised polypropylene nanocomposite: Effect of processing conditions

The thermal properties and fire behaviour of polypropylene (PP) nanocomposites were investigated using differential scanning calorimetry, dynamic-mechanical analysis, thermogravimetric analysis and glow wire test. In order to study the morphological structure of the materials obtained, TEM and XRD analyses were also carried out. The nanocomposites were prepared using the melt intercalation technique in a co-rotating intermeshing twin screw extruder. Particular attention was given to studying the influence of different processing conditions (barrel temperature profile and screw rate) and compositions of PP-nanoclay blends (clay content, use of compatibiliser) on the thermal properties of the nanocomposites.The results show that all the properties analysed were strongly influenced by the nanocomposite composition; instead, the processing conditions greatly affect only the dynamic-mechanical properties. DSC curves show that the crystallinity is deeply influenced by the presence of the clay in the matrix, owing to the fact that the filler acts as nucleating agent. DMA curves show that materials processed at low temperature profile and high shear stress, i.e. when a good clay dispersion is achieved, are characterised by an enhanced modulus, thus indicating that the incorporation of clay into the PP matrix remarkably enhances its stiffness and has good reinforcing effects. TGA traces in oxidizing atmosphere show a drastic shift of the weight loss curve towards higher temperature and no variation of the onset temperature (i.e. the temperature at which degradation begins). The TGA analyses in inert atmosphere show instead marked increase of this parameter (about 200 °C) and no shift of weight loss curves. Glow wire results highlight that polymer nanocomposites are characterised by enhanced fire behaviour.     

Thermal degradation behaviors of a novel nanocomposite based on polypropylene and Co-Al layered double hydroxide

The thermal degradation behaviors of a novel nanocomposite based on polypropylene and organic Co/Al layered double hydroxide (PP/CoAl-LDH) were studied via thermogravimetric analysis (TGA) in the present work. The thermal degradation activation energies of the PP/CoAl-LDH nanocomposite were determined via Friedman and Flynn-Wall-Ozawa methods, and were compared with those of neat PP. The relationship between the organic CoAl-LDH concentration and the activation energies in PP/CoAl-LDH nanocomposite also has been investigated. An internal reason and an outer reason leading to high fire retardancy of PP/CoAl-LDH nanocomposite were proposed. The presence of CoAl-LDH tended to increase significantly the decomposition activation energy of nanocomposite at full-scale temperature and had an important influence on both of internal and outer reasons.     

Synergistic effect of nanoflaky manganese phosphate on thermal degradation and flame retardant properties of intumescent flame retardant polypropylene system

Nanoflaky manganese phosphate (NMP) was synthesized from manganese nitrate and trisodium phosphate dodecahydrate, and used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame retardant (IFR) system. The thermogravimetric analysis (TGA), real time Fourier-transform infrared (RTFTIR) spectroscopy measurements, cone calorimeter (CONE) and microscale combustion calorimeter (MCC) were used to evaluate the synergistic effects of NMP on PP/IFR system. When IFR + NMP was fixed at 20 wt% in flame retardant PP system, the TGA tests showed that NMP could enhance the thermal stability of PP/IFR system at initial temperature from about room temperature to 440 °C and effectively increase the char residue formation. The RTFTIR results revealed that NMP could clearly change the decomposition behavior of PP in PP/IFR system, which promotes decomposition at the initial temperature from about room temperature to 260 °C and forms more effective barrier layer to protect PP from decomposing at high temperature from about 260 °C to 500 °C. The CONE tests indicated that the addition of NMP in PP/IFR system not only reduced the peak heat release rate (HRR), but also prolonged the ignition time. The MCC results revealed that PP/IFR/NMP system generated less combustion heat over the course of heating than that of PP/IFR system. And scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to explore the char residues of the PP/IFR systems with and without NMP.     

Effect of acid treated multi-walled carbon nanotubes on the mechanical, permeability, thermal properties and thermo-oxidative stability of isotactic polypropylene

The effect of acid treatment of multi-walled carbon nanotubes (MWCNTs) on the mechanical, thermal and mainly thermo-oxidative stability of isotactic polypropylene (iPP) was evaluated. From the acid treatment surface carboxylic groups were mainly formed, while the nanotubes' length was gradually reduced by increasing the treatment time. Young's modulus, tensile strength and storage modulus of the iPP/MWCNT nanocomposites were increased by increasing the treatment time of the MWCNTs, due to finer dispersion inside the polymer matrix, as revealed by TEM and micro-Raman spectroscopy. Furthermore, the nanotubes acted as nucleating agents, an effect more pronounced with finer filler dispersion. Thermal stability in an inert atmosphere also increased. Thermo-oxidative stability tests in air and O₂ revealed that oxidative degradation took place in two stages. In the first stage, corresponding to temperatures up to 230 °C, the MWCNTs accelerated the oxidation of iPP, while at higher than 300 °C temperatures the trend was reversed. Incubation studies proved that, at the first stages, oxidation was due to random chain scission of iPP and oxygen uptake. This behaviour was accelerated by the MWCNTs' surface carboxylic groups and, as found by O₂ permeability studies, was mainly a surface process. In the second stage, due to the shielding effect of MWCNTs, the removal of the gases produced during decomposition was hindered. At this stage the presence of MWCNTs resulted in more thermo-oxidatively stable nanocomposites.     

Effect of thermal history on the mechanical properties of three polypropylene impact-copolymers

The effect of thermal history on static mechanical properties and impact fracture behavior of three reactor polypropylene impact-copolymers (ICPPs) was investigated for three ICPPs prepared using commercial Innovene^®, Unipol^® and Spheripol^® polymerization technologies. Multiple extrusion employing a co-rotating twin-screw extruder resulted in a significant reduction of the molecular weight of the PP homopolymer phase evidenced by the increasing melt flow index (MFI). Neither cross-linking of the ethylene-propylene rubber (EPR) phase nor EPR particle coarsening was detected for any of the ICPPs after 5 consecutive extrusions. Decreasing molecular weight of the PP homopolymer phase caused change in the crystalline morphology of injection molded specimens due to the change in crystallization kinetics and reduction of the number of tie molecules, however, the overall degree of crystallinity did not change, significantly. The static tensile mechanical properties (E, σ_y, ?_b), critical strain energy release rate, G_c, and the Charpy notched impact strength, a_k, decreased with increasing MFI in a monotonous manner for all the ICPPs investigated. Despite significant differences between the absolute values of the mechanical properties for the three ICPPs, the MFI dependence of the σ_y and G_c relative to that for the unaffected ICPP fell on a single master curve for all of them. High-speed digital camera, used to follow the fracture process during the instrumented impact test, revealed no significant change of the small scale yielding fracture process with increasing MFI. This was in an agreement with the negligible change in the size of the crack tip plastic zone, R_p, predicted using simple mixed mode fracture model. The plane strain value of the critical strain energy release rate, G_1c, calculated from the measured G_c for the INN (2.4 kJ/m²), UNI (2.8 kJ/m²) and SPH (3.5 kJ/m²) using a simple LEFM model did not exhibit significant dependence on the number of extruder passes. The observed differences between the three ICPPs were ascribed to the significantly larger EPR content in UNI compared to the other two ICPPs and significantly larger content of isotactic PP homopolymer in the INN compared to the remaining two ICPPs.     

Microencapsulation of bisphenol-A bis (diphenyl phosphate) and influence of particle loading on thermal and fire properties of polypropylene and polyethylene terephtalate

Microencapsulated flame retardant, bisphenol-A bis (diphenyl phosphate) (BDP), with a silane shell was prepared by sol–gel process with the goal of incorporating them in polymeric matrices by melt blending to improve the flame retardancy of isotactic polypropylene (iPP) and polyethylene terephtalate (PET). The influence of the loading content on thermal transitions has been studied by differential scanning calorimetry (DSC), the thermal stability of the polymer/microcapsules composites has been assessed by thermogravimetric analysis (TGA) and cone calorimetry has been used to study the fire reaction. It was noticed that the microcapsules have a limited influence on the thermal transitions of iPP matrix, but a decrease of the melting and glass transition temperatures was detected for the PET microcomposites. TGA results showed that the addition of microcapsules could improve char formation of the PET systems both in nitrogen and in air atmospheres, whereas only a small improvement of the thermal stability was detected in oxidative atmosphere for the iPP samples. Furthermore, cone calorimeter experiments show that the incorporation of microcapsules in the iPP gives almost no improvement in the iPP fire reaction. However, the microcapsules act as flame retardant in PET reducing the heat release rate during the combustion and the total heat evolved. Therefore, microcapsules can act as a char promoter agent to enhance the fire resistance in the case of PET.     

Crystallization,mechanical, thermal and rheological properties of polypropylene composites reinforced by magnesium oxysulfate whisker

Polypropylene(PP) composites containing magnesium oxysulfate whisker(MOSw) or lauric acid(LA) modified MOSw(LAMOSw) were prepared via melt mixing in a torque rheometer. The heterogeneous nucleating effect of LAMOSw was clearly observed in polarized light microscopy(PLM) pictures with the presence of an abundance of small spherulites. MOSw exhibited no nucleation effect and formed a few spherulites with large size. Compared with PP/MOSw composites, PP/LAMOSw exhibited better impact strength, tensile strength and nominal strain at break, ascribing to three possible reasons:(i) more β-crystal PP formed,(ii) better dispersity of LAMOSw in PP matrix and(iii) the plasticizing effect of LA. The results of dynamic mechanical thermal analysis(DMTA) indicated that brittleness of the PP matrix at low temperature was improved by the addition of LAMOSw, while the interfacial interactions between MOSw and PP matrix were actually weakened by LA, as evidenced by the higher tanδ values over the entire range of test temperatures. In terms of the rheological properties of the composites, both the η* and G′ at low frequencies increase with the addition of MOSw or LAMOSw, indicating that the PP matrix was transformed from liquid-like to solid-like. However, a network of whiskers did not form because no plateau was found in the G′ at low frequencies. With low filler content, LAMOSw produced a stronger solid-like behavior than MOSw mainly due to the better dispersion of the LAMOSw in PP matrix. However, for highly-filled composites, the η* of PP/LAMOSw at low frequencies was smaller than that of PP/MOSw composite, since the particleparticle contact effect played a major role.     

Effect of compatibilisers on mechanical and thermal properties of bentonite filled polypropylene composites

Bentonite filled polypropylene composites were prepared using a Polydrive Thermo Haake, internal mixer at 180 °C and at 50 rpm of rotor speed. Effect of compatibilisers on mechanical, thermal, water absorption and morphological properties of bentonite filled polypropylene composites was investigated. Two types of compatibilisers namely, palm oil fatty acid additive (POFA) and polypropylene grafted-maleic anhydride (PPMAH) have been used in this study. The mixing of the composites improved with the addition of POFA. The impact strength and elongation at break increased with the presence of both compatibilisers whilst, tensile strength and Young's modulus improved only with addition of PPMAH. Morphological investigation using SEM revealed that the improvement in impact strength and elongation at break was due to enhancement of the interfacial adhesion between bentonite and PP. The thermal stability of bentonite filled PP improved with the incorporation of POFA and PPMAH. Less percentage of water absorption has been observed in PP-bentonite system with PPMAH.     

Effect of nano-filler dispersion on the thermal, mechanical and water sorption properties of green environmental polymer

Partially exfoliated nanocomposite（2） has been synthesized by intercalation of poly（propylene carbonate）（PPC） into commercial clay,Cloisite 20B（PPC/C-20B）.Nanocomposite 2 was characterized phiso-chemically and exhibited high thermal,mechanical and anti-water sorption properties as compared to PPC and intercalated nanocomposite（1） of PPC/C-20B having same amount of clay.TGA results revealed that the thermal decomposition temperature(T_d,50%) of 2 increased significantly,being 40 K and 17 K higher than that of pure PPC and 1,respectively,while DSC measurements indicated that the nano-filler dispersion of 2 increased the glass transition temperature from 21℃to 31℃.Accordingly,2 showed high elastic modulus,hardness and anti-water absorption capacity.These thermal,mechanical and anti-water absorption improvements are of great importance for the application of PPC as packaging and biomaterials.     

Structure and properties of composites of highly crystalline cellulose with polypropylene: Effects of polypropylene molecular weight

Composite of highly crystalline fibrous cellulose (CE) and polypropylene (PP) of different molecular weights () was prepared via melting-mixing, maleic anhydride grafted polypropylene (MAPP) was used as a compatibilizer. And the effects of molecular weight of PP on the properties of the composites were investigated. Through the studying of mechanical properties, dynamic mechanical properties, melting and crystallization behaviors, thermo-oxidative properties, water absorption behaviors, and the morphology of the composites, it was found that PP with higher molecular weight revealed stronger interfacial interaction with cellulose in the composites. Compared with the lower molecular weight, the composites derived from higher molecular weight of PP exhibited stronger tensile strength at the same cellulose content.     

Effect of a novel charring-foaming agent on flame retardancy and thermal degradation of intumescent flame retardant polypropylene

A new triazine polymer was synthesized by using cyanuric chloride, ethanolamine and ethylenediamine as raw materials. It is used both as a charring agent and as a foaming agent in intumescent flame retardants, designated as charring-foaming agent (CFA). Effect of CFA on flame retardancy, thermal degradation and mechanical properties of intumescent flame retardant polypropylene (PP) system (IFR-PP system) has been investigated. The results demonstrated that the intumescent flame retardant (IFR) consisting of CFA, APP and Zeolite 4A is very effective in flame retardancy of PP. It was found that when the weight ratio of CFA to APP is 1:2, that is, the components of the IFR are 64 wt% APP, 32 wt% CFA and 4 wt% Zeolite 4A, the IFR presents the most effective flame retardancy in PP systems. LOI value of IFR-PP reaches 37.0, when the IFR loading is 25 wt% in PP. It was also found that when the IFR loading is only 18 wt% in PP, the flame retardancy of IFR-PP can still pass V-0 rating, and its LOI value reaches 30.2. TGA data obtained in pure nitrogen demonstrated that CFA has a good ability of char formation itself, and CFA shows a high initial temperature of the thermal degradation. The char residue of CFA can reach 35.7 wt% at 700 °C. APP could effectively promote the char formation of the APP-CFA system. The char residue reaches 39.7 wt% at 700 °C, while it is 19.5% based on calculation. The IFR can change the thermal degradation behaviour of PP, enhance T_max of the decomposition peak of PP, and promote PP to form char, based upon the results of the calculation and the experiment. This is attributed to the fact that endothermic reactions took place in IFR charring process and the char layer formed by IFR prevented heat from transferring into inside of IFR-PP system. TGA results further explained the effective flame retardancy of the IFR containing CFA.     

Influence of SEBS-g-MA on morphology, mechanical, and thermal properties of PA6/PP/organoclay nanocomposites

Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organically modified clay (organoclay) toughened with maleated styrene-ethylene-butylene-styrene (SEBS-g-MA) were prepared by melt compounding using co-rotating twin-screw extruder followed by injection molding. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the structure of the nanocomposites. The mechanical properties of the nanocomposites were determined by tensile, flexural, and notched Izod impact tests. The single edge notch three point bending test was used to evaluate the fracture toughness of SEBS-g-MA toughened PA6/PP nanocomposites. Thermal properties were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). XRD and TEM results indicated the formation of the exfoliated structure for the PA6/PP/organoclay nanocomposites with and without SEBS-g-MA. With the exception of stiffness and strength, the addition of SEBS-g-MA into the PA6/PP/organoclay nanocomposites increased ductility, impact strength and fracture toughness. The elongation at break and fracture toughness of PA6/PP blends and nanocomposites were increased with increasing the testing speed, whereas tensile strength was decreased. The increase in ductility and fracture toughness at high testing speed could be attributed to the thermal blunting mechanism in front of crack tip. DSC results revealed that the presence of SEBS-g-MA had negligible effect on the melting and crystallization behavior of the PA6/PP/organoclay nanocomposites. TGA results showed that the incorporation of SEBS-g-MA increased the thermal stability of the nanocomposite.     

The mechanical and thermal behaviors of glass bead filled polypropylene

Notch Izod impact strength of poly(propylene) (PP)/glass bead blends was studied as a function of temperature. The results indicated that the toughness for various blends could undergo a brittle‐ductile transition (BDT) with increasing temperature. The BDT temperature (T_BD) decreased with increasing glass bead content. Introducing the interparticle distance (ID) concept into the study, it was found that the critical interparticle distance (ID_c) reduced with increasing test temperature correspondingly. The static tensile tests showed that the Young's modulus of the blends decreased slightly first and thereafter increased with increasing glass bead content. However, the yield stress decreased considerably with the increase in glass bead content. Dynamic mechanical analysis (DMA) measurements revealed that the heat‐deflection temperature of the PP could be much improved by the incorporation of glass beads. Moreover, the glass transition temperature (T_g) increased obviously with increasing glass beads content. Differential scanning calorimetry (DSC) results implied that the addition of glass beads could change the crystallinity as well as the melting temperature of the PP slightly. Thermogravimetric analysis (TGA) measurements implied that the decomposition temperature of the blend could be much improved by the incorporation of glass beads. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of magnetic nanoparticles on the thermal properties of some hydrogels

Magnetic hydrogels (ferrogels) based on poly(vinyl alcohol) (PVA) and poly(hydroxyethyl methacrylate) (PHEMA) with magnetite (Fe₃O₄) nanoparticles were prepared. PVA ferrogels were synthesised by submitting the aqueous solution of polymer and Fe₃O₄ to freezing-thawing (F-T) cycles yielding a physical gel. Different samples were prepared by varying (i) the concentration of PVA, (ii) the concentration of magnetite and (iii) the number of F-T cycles applied. PHEMA ferrogels were prepared by a crosslinking polymerization reaction in the presence of magnetite yielding chemical gels. Different samples were prepared by varying (i) the concentration of HEMA, (ii) the concentration of EGDMA and (iii) the concentration of magnetite nanoparticles. All ferrogel samples were first dried before been analysed in a thermogravimetric analyzer. The resulting thermograms showed that the concentration of magnetite nanoparticles does affect the thermal stability of either ferrogels system, a general improvement in comparison with PVA and PHEMA hydrogels, respectively, being observed. The apparent activation energy (E_a) of the thermal degradation for PVA ferrogels was evaluated and calculated applying the Flynn-Wall and the Kissinger methods. Values of apparent E_a increased with the content of Fe₃O₄ in the ferrogel sample.     

The thermal degradation behaviour of polydimethylsiloxane/montmorillonite nanocomposites

A series of novel polydimethylsiloxane/montmorillonite (PDMS/MMT) nanocomposites was prepared. The thermal degradation behaviour of these nanocomposites was studied by means of Thermal Volatilization Analysis (TVA) and Thermogravimetric Analysis (TGA). The major degradation products were identified as cyclic oligomeric siloxanes from D₃ to D_7, and higher oligomeric siloxane residues. Other minor degradation products include methane, bis-pentamethylcyclotrisiloxane, propene, propanal, benzene and dimethylsilanone. The results demonstrate that the nanoclay significantly alters the degradation behaviour of the PDMS network, modifying the profile of the thermal degradation and reducing the overall rate of volatiles evolution. The results also indicate that the nanoclay promotes the formation of dimethylsilanone and benzene by inducing low levels of radical chain scission.     

Effect of ZnO and organo-modified montmorillonite on thermal degradation of poly(methyl methacrylate) nanocomposites

Since a few years ago, a topic of interest consists in developing composites filled with nanofillers to improve thermal degradation and flammability property of poly(methyl methacrylate) (PMMA). In the present work, the effects of ZnO nanoparticles and organo-modified montmorillonite (OMMT) on the thermal degradation of PMMA were investigated by thermogravimetric analysis (TGA). PMMA-ZnO and PMMA-OMMT nanocomposites were prepared by melt blending with different (2, 5, and 10 wt%) loadings. SEM and TEM analyses of nanocomposites were performed in order to investigate the dispersion of nanofillers in the matrix. According to TGA results, the addition of ZnO nanoparticles does not affect the thermal degradation of PMMA under an inert atmosphere. However, in an oxidative atmosphere, two contrary effects were observed, a catalytic effect at lower concentration of ZnO in the PMMA matrix and a stabilizing effect when the ZnO concentration is higher (10 wt%). In contrast, the presence of OMMT stabilizes the thermal degradation of PMMA whatever be the atmosphere. Differential thermal analysis (DTA) curves showed surprising results, because a dramatic change of exothermic reaction of the PMMA degradation process to an endothermic reaction was observed only in the case of OMMT. During the degradation of PMMA-ZnO nanocomposites, pyrolysis-gas chromatography coupled to mass spectrometer (Py-GC/MS) showed an increase in the formation of methanol and methacrylic acid while a decrease in the formation of propanoic acid methyl ester occurred. In the case of PMMA-OMMT systems, a very significant reduction in the quantity of all these degradation products of PMMA was observed with increasing OMMT concentration. It is also noted that during PMMA-OMMT degradation less energy was released as the decomposition is an endothermic reaction and the material was cooled.     

Effect of thermal degradation on rheological properties for poly(3-hydroxybutyrate)

Thermal degradation at processing temperature and the effect on the rheological properties for poly(3-hydroxybutyrate) have been studied by means of oscillatory shear modulus and capillary extrusion properties, with the aid of molecular weight measurements. Thermal history at processing temperature depresses the viscosity because of random chain scission. As a result, gross melt fracture hardly takes place with increasing the residence time in a capillary rheometer. Moreover, it was also found that the molecular weight distribution is independent of the residence time, whereas the inverse of the average molecular weight is proportional to the residence time. Prediction of average molecular weight with a constant molecular weight distribution makes it possible to calculate the flow curve following generalized Newtonian fluid equation proposed by Carreau as a function of temperature as well as the residence time.     

Effect of new melamine-terephthaldehyde resin modified graphene oxide on thermal and mechanical properties of PVC

In this study a new melamine-terephthaldehyde resin modified graphene oxide was synthesized and used as a reinforcement of poly(vinyl chloride) (PVC). Characterization, morphology, thermal and mechanical properties of the nanocomposites were examined by means of attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and tensile properties. The first hydrochloric acid releasing data of poly(vinyl chloride) was removed by incorporation of the modified graphene oxide as compare to the neat polymer. The temperatures at 2 wt% losses, main decomposition temperatures, maximum decomposition temperatures, also shift to higher temperature in the corresponding nanocomposites as compared to the neat PVC. The tensile strength and elongation at break of the nanocomposite films was increased as compared to the neat PVC. The interesting results in crystallinity of PVC were observed with adding 5 wt% of the modified graphene oxide.     

Kinetics of thermal degradation and estimation of lifetime for polypropylene particles: Effects of particle size

The thermal stability and degradation behavior of polypropylene (PP) particles having diameter varying from few micrometers to nanometers were studied by thermogravimetric analysis (TGA). The PP particles of average diameter ∼20 μm, ∼10 μm, ∼5 μm, ∼1 μm and <500 nm were studied over a range of temperature from 25 to 600 °C in N₂ atmosphere and heating rates of 5, 10 and 15 °C/min. Thermal stability of PP particles initially decreases and then increases as particle size further decreases to nanometer scale. The five single heating rate techniques such as Friedman, Freeman-Carroll, Chang, Coats-Redfern and second Kissinger; and three multiple heating rate techniques such as the first Kissinger, Kim-Park and Flynn-Wall were used to compute the kinetic parameters of degradation reaction, e.g., activation energy (E_a), order of reaction (n) and frequency factor [ln(Z)]. The lifetime of macro-, micro- and nanosized PP particles was also estimated by a method proposed by Toop. It was found that the activation energy and lifetime of nanosized PP particles are moderately high compared to the microsized PP particles. Moreover, the decomposition temperature, order of reaction (n), frequency factor [ln(Z)] not only depend on the heating rate and calculation technique but also on the particle size of polymer. The results are compared with macrosized PP.