PPS/recycled PEEK/ carbon nanotube composites: Structure,properties and compatibility

Blends of poly(phenylene sulfide) (PPS) and recycled poly(ether ether ketone) (r‐PEEK) were prepared using a twin‐screw extruder. The carbon nanotube (CNT) added to the blends not only improved the compatibility of the two polymers, but also affected the morphology of the immiscible PPS/r‐PEEK blends. R‐PEEK always forms the dispersed phase and PPS the continuous phase in such blends. In the composite, CNT particles were observed in the PPS phase, mostly distributes in the interface between PPS and PEEK. The results show that r‐PEEK improves the impact and tensile strength of PPS, but does not provide nucleation effect on PPS. However, CNT improved the flexural modulus of PPS/r‐PEEK blends and promoted the crystallization of r‐PEEK rather than that of PPS. The prepared PPS/r‐PEEK blends provided larger electrical conductivity than neat polymers. Adding 20 wt % CNT to blend resulted in composite with the minimum volume resistivity, a reduction of four orders of magnitude, compared with that of the neat blend. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42497.     

Effect of TPU hard segment content on the rheological and mechanical properties of PLA/TPU blends

Blends of an amorphous polylactide (PLA) with three different thermoplastic polyurethane (TPU) grades having various hard segment (HS) contents are prepared at the blending ratio of 85/15 wt% through a twin-screw extruder (TSE) at processing temperatures of 150 and 190°C. Blends of a semicrystalline PLA with 15 wt% of the noted TPU grades are also processed in the TSE at 190°C to investigate the matrix crystallization effect on the morphology and property enhancements. The rheological experiments reveal that the increase in TPU HS content significantly increases the phase compatibility between PLA and TPU as also suggested by the finer morphology of the TPU phase, although the use of lower HS TPUs is more favorable to enhance the ductility and impact properties of the blends.     

Effects of thermoplastic poly(ether-ester) elastomer and bentonite nanoclay on properties of poly(lactic acid)

This work presented the influence of thermoplastic poly(ether-ester) elastomer (TPEE) and bentonite (BTN) on improving the mechanical and thermal properties of poly(lactic acid) (PLA). PLA was initially melt mixed with TPEE at six different loadings (5–30 wt%) on a twin screw extruder and then injection molded. The mechanical tests revealed an increasing impact strength and elongation at break with increasing TPEE loading, but a diminishing Young's modulus and tensile strength with respect to pure PLA. The blend at 30 wt% TPEE provided the optimum improvement in toughness, exhibiting an increase in the impact strength and elongation at break by 3.21- and 10.62-fold over those of the pure PLA, respectively. Scanning electron microscopy analysis illustrated a ductile fractured surface of the blends with the small dispersed TPEE domains in PLA matrix, indicating their immiscibility. The 70/30 (wt/wt) PLA/TPEE blend was subsequently filled with three loadings of BTN (1, 3, and 5 parts by weight per hundred of blend resin [phr]), where the impact strength, Young's modulus, tensile strength and thermal stability of all the blends were improved, while the elongation at break was deteriorated. Among the three nanocomposites, that with 1 phr BTN formed exfoliated structure and so exhibited the highest impact strength, elongation at break, and tensile strength compared to the other intercalated nanocomposites. Moreover, the addition of BTN was found to increase the thermal stability of the neat PLA/TPEE blend due to the barrier properties and high thermal stability of BTN.     

PPS/CaCO3复合材料的结晶行为及动态力学研究

采用DSC、DMA等测试手段研究了PPS/CaCO_3复合材料的结晶行为和动态力学性能。通过对冷结晶峰值温度T_(?)、半结晶时间t_(1/2)、结晶焓△H_c等参数的分析,结果表明:CaCO_3的添加阻碍了PPS分子链的运动,导致了体系结晶速率减小,结晶能力下降,且阻碍作用在CaCO_3含量为3%时最为明显。同时,通过DMA测试,表明CaCO_3的添加使PPS的储能模量和损耗模量都有所增加,其中损耗模量也在CaCO_3含量为3%时达到最大。     

TPU增韧改性POM的研究

利用双螺杆挤出机制备了聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)和POM/TPU/异氰酸酯预聚物(Z)共混物.采用力学性能测试方法、偏光显微镜(PLM)、傅立叶转换红外线光谱 (FTIR)、扫描电子显微镜(SEM)等研究了共混物的力学性能、结晶行为及形态结构.结果表明,不同种类TPU增韧的共混物的缺口冲击强度和断裂伸长率都随TPU含量的增加而增加,TPU(95A)增韧的POM/TPU共混物的刚性较好,TPU(250)增韧的POM/TPU共混物的韧性较好;Z能促进TPU在基体树脂中的均匀分散,增强两相界面的粘结力,并能细化球晶.     

Effect of rubber interparticle distance distribution on toughening behavior of thermoplastic polyolefin elastomer toughened polypropylene

In this study, a blend of polypropylene (PP) and two types of thermoplastic polyolefin elastomers (TPO) were prepared by melt mixing. The TPOs were either ethylene‐ or propylene‐based copolymer. The mechanical response and morphology of the blends were investigated using tensile and impact tests and scanning electron microscopy technique. There was significant increase in the impact strength of the TPO‐modified PP, which was an outcome of fine dispersion of TPO inclusions. In particular, the blends containing PP‐based TPO exhibited dramatic enhancement in toughness energy as featured by a plastic deformation in tensile test. The brittle‐tough transition had several deviations from theoretical models, in which generally the interparticle distance criterion was realized as a single parameter, only controlled the transition of brittle to tough behavior. Moreover, the brittle‐tough transition in tensile and impact mode tests was not coincident in the blend with a broad distribution of interparticle distance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44068.     

Effects of the chain‐extender content on the structure and performance of poly(lactic acid)–poly(butylene succinate)–microcrystalline cellulose composites

Composites of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) and microcrystalline cellulose (MCC) as reinforcements of the polymer matrix were prepared by melt blending to improve the brittleness of PLA. As a reactive compatibilizer, a chain extender was used in an attempt to solve the composites’ interfacial problems and to improve their mechanical properties; Fourier transform infrared spectroscopy indicated that the chain extender functionally reacted with PLA, PBS, and MCC mainly through end carboxyls or end hydroxyls. Scanning electron microscopy indicated that the chain extender significantly improved the cohesive interfacial forces. Differential scanning calorimetry and X‐ray diffraction showed that the chain extender inhibited crystallization, and these effects were greater when its percentage was increased. The addition of chain extender improved the tensile and impact strength of the composites, and this improvement was proportional to the chain‐extender percentage. However, the elongation at break decreased when the chain‐extender percentage was over 0.5% because of mild crosslinking within the resin matrix. Rheology indicated that the complex viscosity and storage and loss moduli of the composites increased with increasing amount of chain extender; this indicated that the addition of chain extender improved the melt strength and processability of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44895.     

Scrutinizing the influence of peroxide crosslinking of dynamically vulcanized EVA/TPU blends with special reference to cable sheathing applications

A novel thermoplastic vulcanizate (TPV) based on the blends of ethylene vinyl acetate/thermoplastic polyurethane (EVA/TPU) at various blend ratios has been developed via dynamic vulcanization at 180 °C using di‐(2‐tert‐butyl peroxy isopropyl) benzene (DTBPIB) peroxide as the cross‐linking agent. Modification of the EVA/TPU blends via dynamic crosslinking significantly improves the tensile strength and modulus of the system and the improvement is more significant for EVA/TPU 50/50 and 60/40 blends. AFM study shows that crosslinked EVA particles are dispersed in the continuous TPU matrix and the dispersed EVA domain sizes are relatively smaller in EVA/TPU 50/50 and 60/40 blends leading to good mechanical properties. FTIR spectroscopy has been used to characterize the specific chemical changes occurring due to dynamic vulcanization. This TPV has excellent retention of physico‐mechanical properties even after reprocessing twice and the blends also have very good thermal resistance as indicated by aging study. The samples were found to exhibit remarkable improvement in oil resistance property as compared to their uncrosslinked counterpart. The creep behavior of the blends significantly improves after dynamic crosslinking and blends with higher TPU content show better creep resistance. Volume resistivity of all the peroxide vulcanized blends is in the range of 10¹³ ohm cm, which is suitable for cable sheathing application. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43706.     

Impact modification of polyacetal by thermoplastic elastomer polyurethane

The main goal of this study was impact modification of polyacetal [polyoxymethylene (POM)] with thermoplastic elastomer polyurethane (TPU). We modified the impact strength of POM 10‐fold. The mechanical properties, thermal behavior, and morphology of POM/TPU blends consisting of 5 to 50% of TPU were studied. It was found that the best impact modification of the blends was at 15% concentration of TPU and the maximum elongation at break was at 30% concentration of TPU. The impact strength of POM/TPU blends can be improved by using diphenylmethane diisocyanate (MDI) as compatibilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2573–2582, 2002     

An efficient plasticization method for poly(lactic acid) using combination of liquid‐state and solid‐state plasticizers

A combined use of solid plasticizer [poly(ethylene glycol), PEG] with a nominal M_w of 2000 g/mol and liquid plasticizer (epoxidized soybean oil, ESO) for plasticizing poly(lactic acid) (PLA) is proposed in this study. This plasticization method brought an obvious improvement in the melting flowability of the modified PLA, which has been verified by a lower balance torque during blending and a four times increase in the melt flow index compared to neat PLA. Meanwhile, the brittleness of this glassy polymer was also improved significantly; all composites with different contents of combined plasticizers displayed an obvious yield stage and toughness fracture surfaces. The mechanisms of the plasticizing effects were investigated by polarizing optical microscopy and scanning electron microscopy. The PLA/ESO/PEG blends formed a complex reinforcement structure. ESO existed as tiny droplets and uniformly dispersed in the PLA spherulites, and strip‐shaped PEG accumulated along the boundaries of interspherulites. The combined use of these two plasticizers, a liquid one and a solid one, had an excellent effect on plasticizing PLA, not only on melt flowability but also on mechanical properties. Thus, the application areas for PLA could be further expanded, such as melt blowing and melt extrusion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46669.     

Study on effects of short glass fiber reinforcement on the mechanical and thermal properties of PC/ABS composites

This article mainly investigated the length distributions of the alkali‐free short glass fibers in specimens and their effect on the mechanical and thermal properties of the composites. The results show that the initial length, addition level and feed way of the fibers have obvious effects on the length distributions of fibers in specimens, and thereby the mechanical and thermal properties of the composites. The main‐direction feed way has an intense shear action on the fibers in specimens. With the increase of the fiber content, the reinforcing effect of fibers on the tensile strength, flexural strength and flexural modulus of the composites is increased, while the impact strength is decreased first and then tends to be stable, and the strength factor (F) of the tensile strength to weld line is significantly reduced. The longer the fiber lengths in specimens are, the more obvious the reinforcing and toughening effects are. To some extent, with the increase of the fiber content, the storage modulus (E′) and loss modulus (E′′) of the specimens are increased, but the loss factor (Tan δ) is reduced. The effect of the fiber initial lengths on the heat‐degradation of composites is smaller than that of the fiber content. Meanwhile, adding fibers can improve the thermal stability of the composites, and this law is also confirmed by the heat deflection temperature (HDT) test. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40697.     

The overall crystallization behavior of polyethylene/wax blends as phase change materials for thermal energy storage: A mini review

This review paper deals with the overall crystallization behavior of polyethylene/wax blends as phase change materials (PCMs) for thermal energy storage with the determination of their thermal properties. The addition of molten wax to the polyethylenes decreases the crystallization and melting temperatures of the blends. However, incorporating fillers to the polyethylene/wax blends can either decrease or increase the crystallization and melting temperatures of the composites depending on the filler type. The normalized enthalpy values of linear low-density polyethylene showed no significant change when increasing the wax content. On the contrary, the normalized enthalpy values of the wax in the blends were lesser than that of pure wax and increased with increasing wax content. Since the wax in the blend had a lower crystallinity compared to pure wax, this influences its effectiveness as a PCM for thermal energy storage. The effect of different polyethylenes on the wax morphology gave rise to enhance phase separation when wax was blended to high-density polyethylene as compared to the other polyethylenes. On the contrary, the effect of various waxes on the morphology of polyethylene resulted in different morphologies due to the molecular weight of the wax used and the structure of the polyethylene chain. The addition of fillers to the polyethylene (PE)/wax samples resulted in enhanced phase separation. The overall isothermal crystallization rate and the equilibrium melting temperature of PEs in the PEs/wax blends were depressed by wax addition due to the wax dilution effect.     

Improved thermal conductivity of ceramic filler‐filled polyamide composites by using PA6/PA66 1:1 blend as matrix

Polyamide‐type composites with improved thermal conductivity are prepared by using polyamide 6(PA6)/polyamide 6,6 (PA66) 1:1 blend as the matrix and aluminum nitride (AlN) as the filler through melt compounding. Field emission scanning electron microscopy coupled with energy dispersive spectrometry (EDS) mapping of Al is used to investigate distribution of AlN. Differential scanning calorimeter is used to investigate the crystallization behavior of the composites. The thermal conductivity of PA6/PA66/AlN composite with 50 wt % AlN is 1.5 W m^?1 K^?1, 88% enhancement compared to those of single polymer based PA6/AlN or PA66/AlN composites. The reason for the improved thermal conductivity is the increased effective volume concentration of AlN in one (probably PA66) phase. The experimental data are fitted into Bruggeman and Agari–Uno model. Composites with similar thermal conductivity are also prepared using silicon carbide as the filler instead of AlN, showing that using PA6/PA66 1:1 blend as the matrix is a universal method to prepare thermally conductive composites with less filler loading. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45371.     

Mechanical,thermal, and conductivity performances of novel thermoplastic natural rubber/graphene nanoplates/polyaniline composites

Conventional polymer blending has a shortcoming in conductivity characteristic. This research addresses the preparation of conductive thermoplastic natural rubber (TPNR) blends with graphene nanoplates (GNPs)/polyaniline (PANI) through melt blending using an internal mixer. The effect of PANI content (10, 20, 30, and 40 wt %) on the mechanical and thermal properties, thermal and electrical conductivities, and morphology observation of the TPNR/GNPs/PANI nanocomposites was investigated. The results showed that the tensile and impact properties as well as thermal conductivity of nanocomposite had improved with the incorporation of 3 wt % of GNPs and 20 wt % of PANI as compared to neat TPNR and reduced with further increase of the PANI content. It was observed that the GNPs and PANI acted as a critical component to improve the thermal stability and electrical conductivity of the TPNR/GNPs/PANI nanocomposites. The most improved conductivity of 5.22 E-5 S/cm was observed at 3 wt % GNPs and 40 wt % PANI. Variable-pressure scanning electron microscopy micrograph revealed the good interaction and distribution of GNPs and PANI within TPNR matrix at PANI loadings lower than 30 wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48873.     

Influence of thermal and morphological characteristics on mechanical responses of polypropylene/γ‐irradiated elastomer blends

The approach of this paper is to examine the mechanical responses of polypropylene (PP)/γ‐irradiated ethylene acrylic elastomer blends and subsequently compare them with the PP/unirradiated ethylene acrylic elastomer blends. Thorough correlations were drawn between the mechanical characteristics of blends and their morphological, thermal, thermomechanical, and fractured surface morphological aspects. The idea of carrying out γ‐irradiation was to introduce crosslinking points in the elastomer phase. For better understanding, correlations between the impact test results and the fractured surface morphologies were analyzed. The limited tensile properties of PP/γ‐irradiated elastomer blends were attributed not only to the poor interfacial adhesion, obtained by fitting with several theoretical mechanical models, but also to the substantially higher elastomer particle size in the blends than in the PP/unirradiated elastomer blends. The higher loss modulus and tan δ values for PP/unirradiated elastomer blends along with the attainment of much smaller particles of elastomers were responsible for the phenomenal increase in impact properties, which was actually attributed to the formation of crazes inside the dispersed phase during applied impact stress. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46597.     

Toughening of an epoxy resin with hydroxy‐terminated poly(arylene ether nitrile) with pendent tertiary butyl groups

Hydroxy‐terminated poly(arylene ether nitrile) oligomers with pendent tert‐butyl groups (PENTOH) were synthesized by the nucleophilic aromatic substitution reaction of 2,6‐dichlorobenzonitrile with tert‐butyl hydroquinone in N‐methyl‐2‐pyrrolidone medium with anhydrous potassium carbonate as a catalyst at 200°C in a nitrogen atmosphere. The PENTOH oligomers were blended with diglycidyl ether of bisphenol A epoxy resin and cured with 4,4′‐diaminodiphenyl sulfone. The curing reaction was monitored with infrared spectroscopy and differential scanning calorimetry. The morphology, fracture toughness, and thermomechanical properties of the blends were investigated. The scanning electron micrographs revealed a two‐phase morphology with a particulate structure of the PENTOH phase dispersed in the epoxy matrix, except for the epoxy resin modified with PENTOH with a number‐average molecular weight of approximately 4000. The storage modulus of the blends was higher than that of the neat epoxy resin. The crosslink density calculated from the storage modulus in the rubbery plateau region decreased with an increase in PENTOH in the blends. The fracture toughness increased more than twofold with the addition of PENTOH oligomers. The tensile strength of the blends increased marginally, whereas the flexural strength decreased marginally. The dispersed PENTOH initiated several toughening mechanisms, which improved the fracture toughness of the blends. The thermal stability of the epoxy resin was not affected by the addition of PENTOH to the epoxy resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermal and mechanical properties of polypropylene/wood‐flour composites

In this research, polypropylene/wood‐flour composites (WPCs) were blended with different contents of wood and/or maleated polypropylene (MAPP) and clay. We found that the addition of MAPP or clay in the formulation greatly improved the dispersion of the wood fibers in the composite; this suggested that MAPP or clay may have played the role of an adhesion promoter in the WPCs. The results obtained with clay indicate that it also acted as a flame retardant. The thermal tests carried out with the produced samples showed an increased crystallization temperature (T_c), crystallinity, and melting temperature (T_m) with wood loading. The increase of the two former parameters was explained by the incorporation of wood flour, which played the role of nucleating agent and induced the crystallization of the matrix polymer. On the other hand, the T_m increase was ascribed to the insulating properties of wood, which hindered the movement of heat conduction. The effects of UV irradiation on T_m and T_c were also examined. T_c increased with UV exposure time; this implied that UV degradation generated short chains with low molecular weight that could move easily in the bulk of the sample and, thus, catalyze early crystallization. The flexural strength and modulus increased with increasing wood‐flour content. In contrast, the impact strength and tensile strength and strain decreased with increasing wood‐flour content. All of these changes were related to the level of dispersion of the wood flour in the polymeric matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reactive compatibilization of PLA/TPU blends with a diisocyanate

This study focuses on the compatibilization of poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends by using 1,4 phenylene diisocyanate (PDI) for the first time, as the compatibilizer. Because of the potential interactions of diisocyanates with ? OH/? COOH, they are useful for reactive processing of PLA/TPU blends in the melt processing. To have insight on the reactively compatibilized structure of PLA/TPU blends, phase morphologies are observed by means of scanning electron microscopy. The mechanical, thermal, and rheological responses of the blends are investigated. The observations are that the brittle behavior of PLA changes to ductile with the addition of TPUs. The addition of PDI improves the tensile properties of the blends. The compatibilization action of PDI is monitored with DMA and rheological experiments. Cross‐over in the G′ and G″ curves of compatibilized blends indicates the relaxation of branches formed in the presence of PDI. The dispersed phase size of TPU decreases in PLA in the presence of PDI due to the improved compatibility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40251.     

Polystyrene and polyester polyurethane elastomer blends compatibilized by SMA

Blends of polystyrene (PS) with polyester polyurethane elastomer (PU‐es) were compatibilized by addition of poly(styrene‐co‐maleic anhydride) (SMA) containing 7 wt % of maleic anhydride. Binary nonreactive (PS/PU‐es) blends, binary reactive (SMA/PU‐es) blends, and ternary reactive blends (PS/SMA/PU‐es) were prepared with 10 and 20 wt % of PU‐es. The maleic anhydride content in the ternary reactive blends was varied through addition of different SMA amounts from 0.5 to 5 wt %. Polyurethane in the blends was crosslinked by using dicumyl peroxide or sulfur to improve its mechanical properties. The experimental processing conditions, such as temperature and rotor speed in an internal mixer, were analyzed before blend preparation by processing the individual polymers, PS and SMA, and the PS/PU‐es nonreactive blend (90/10), to prevent the degradation of the polymer during melt mixing and to assure macroscopic homogeneity. The torque behavior during the mixture indicated a grafting copolymerization, which was responsible for the significant drop of the PU‐es domain size in the glassy matrix, as observed by scanning electronic microscopy (SEM). The miscibility of the glassy matrix, which was shown to be dependent on the composition and the phase behavior of ternary blends, became very complex as the SMA concentration increased, as concluded from dynamical–mechanical analysis. Blends containing 20 wt % of PU‐es presented an increase up to a factor of 2 in the deflection at break in relation to PS. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2297–2304, 2004     

Structure–property relationship in PP/LDPE blend composites: The role of nanoclay localization

This article reports, for the first time, on how the kinetics and thermodynamics of the melt‐processing control the nano/micro‐structure development and properties of nanoclay‐filled polypropylene (PP)/low‐density polyethylene (LDPE) blend ternary composites. Morphological characterization suggests that the nano/micro‐structure of the PP/LDPE (80/20) blend can be controlled by incorporating nanoclay alone or by adding a mixture of organoclay and maleated compatibilizers. Simultaneous mixing of PP, LDPE, maleated compatibilizers, and organoclay results in homogeneous distribution of intercalated silicate layers in all the phases of the blend, a feature which profoundly affects the thermal stability and tensile and rheological properties of the blend composites. For example, the elongation‐at‐break for PP increases from 28.1 to 155.6% for composite containing both organoclay and maleated compatibilizers, whereas the thermal stability for PP increases from 269.8 to 303.3 °C for the same composite. However, the impact strength of the PP/LDPE blend decreases with incorporation of organoclay, regardless of the phase in which the nanoclay particles are localized. In summary, the obtained results show that regardless of the phase in which the nanoclay is localized, the morphology, and hence the properties, of the ternary composites are superior to those of the neat blend. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46193.