Cellulose/syndiotactic polypropylene composites: Effects of maleated polypropylene as a compatibilizer and silanized cellulose on the morphology and tensile properties

To improve the interaction between syndiotactic polypropylene (SPP) and fibrous cellulose (FC), the effects of the addition of maleated polypropylene (MAPP) and FC surface modification with 3‐aminopropyltriethoxysilane (APTES) on SPP/FC composites were studied with respect to the morphology and the tensile properties. The addition of MAPP brought about an improvement in the interfacial adhesion between SPP and FC according to scanning electron microscopy observations and tensile testing. This improvement was, however, less effective than the improvement in the interfacial adhesion between isotactic polypropylene (IPP) and FC. SPP and MAPP partially or microscopically phase‐separated because of the IPP‐like polymer chain structure of MAPP. With respect to the compatibility between SPP and FC, FC surface modification with APTES was more suitable. The increase in Young's modulus was remarkable in the SPP/silanized FC composite with APTES. The tensile strength of the SPP/silanized FC composite with APTES was, however, considerably lower than that of the SPP/FC/MAPP composite. These results suggest that interfacial improvement between SPP and FC requires a compatibilizer or a surface modifier with a suitable primary structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and mechanical properties of composite of fibrous cellulose and maleated polyethylene

Fibrous cellulose and maleated polyethylene (FC–MPE) composites were prepared under melt mixing by maleation of polyethylene (PE) to obtain maleic anhydride (MA) grafted PE (MPE) and successive compounding of the resultant MPE with fibrous cellulose (FC). When increasing the content of added MA to 2 wt %, the grafting efficiency of MA decreases gradually to 84% and the grafted MA chains become longer. Scanning electron microscopy (SEM) reveals strong adhesion of MPE to FC in the FC–MPE composite, which is probably due to the increased compatibility between MPE and FC, in contrast to no adhesion of unmaleated PE (UPE) to FC in the FC–UPE composite. This difference in interfacial structure between the FC–MPE and FC–UPE composites results in quite different mechanical properties for them. With an increase in the FC content to 60 wt %, the tensile strength of the FC–MPE composite increases significantly and reaches 125% that of pure PE. Furthermore, the larger Young's modulus, larger bending elastic modulus, and smaller elongation of the FC–MPE composite strongly indicate effective transfer of the high tensile strength and elasticity of FC to the MPE matrix through the strong adhesion between FC and MPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1971–1980, 2002; DOI 10.1002/app.10428     

Morphology,crystalline features,and tensile properties of syndiotactic polypropylene blends

Syndiotactic polypropylene (sPP) was modified with ethylene–octene copolymer (EOC) and ethylene–propylene rubber (EPR), with test samples prepared in a twin‐screw extruder and then injection‐molded. The phase morphology, rheology, and thermal and tensile properties of the modified sPP were investigated. Atomic force microscopy studies showed how the phase morphology of the sPP blends with elastomers depended on the blend compositions, and the results compared with the storage modulus at low frequency. EOC and EPR were dispersed phase in an sPP matrix with spherical shapes when the dispersed content was 20 wt % or lower. The phase cocontinuity started around 40 wt % EOC for the sPP–EOC blends and around 60 wt % EPR for the sPP–EPR. The dispersed phase then formed more complex elongated shapes. The rheological and thermal properties were affected by the sPP–elastomer interphase. EOC promoted the crystallization of sPP; this increased the crystallization temperature and rate. In contrast, EPR had the opposite effect on the crystallization behavior, and the results indicate that sPP and EPR were not completely separated. The tensile properties were studied from ?20 to 100 °C. We found that the tensile properties at low temperature could be improved without a loss in high‐temperature properties. In the particular case of 20 wt % EOC, both the strain at yield and strain at break of the sPP–EOC blend were improved at both ?20 and 100 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44611.     

Influence of maleated polypropylene on mechanical properties of composite made of viscose fiber and polypropylene

The purpose of this work was to study how viscose fiber behaves in polypropylene (PP) matrix when maleated polypropylene (MAPP) is used as a coupling agent. The influences of processing conditions on composite properties was of interest. Composites were characterized by FTIR and mechanical testing. The most notable result was the effect of the MAPP concentration on the tensile strength of the composites; the tensile strength increased from 40 to 69 MPa when MAPP was added in amounts up to 6 wt % of the fiber weight. The interaction between MAPP and fiber was confirmed with FTIR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1895–1900, 2003     

Syndiotactic polypropylene/microfibrous cellulose composites: Effect of filler size on tensile properties

Syndiotactic polypropylene (SPP)/ethanol swelled microfibrous cellulose (MFC) composite was prepared by a melting mixer, and its morphology and tensile properties were studied. The scanning electron microscope microphotograph did not show the aggregated MFC part up to the 40 wt % MFC loading content, and the Young's modulus was exponentially increasing with the increase of the MFC loading content. These results suggested that the MFC was well‐dispersed in the SPP matrix by an ethanol surfactant work. The Young's modulus was much higher than that of the composite with commonly used fibrous cellulose and moreover, exceeded the theoretical one obtained from the Halpin‐Tsai equation. The differential scanning calorimetry and wide‐angle X‐ray diffraction measurements showed that the MFC acted as a good α‐nucleation agent for SPP. It was found that the excessive Young's modulus of the MFC composite was originated from an increase of that of the SPP matrix induced by the α‐nucleation effect. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characteristics of composites of high‐crystalline cellulose with polypropylene: Effects of maleated polypropylene and cellulose content

Binary composites of high‐crystalline fibrous cellulose with polypropylene (PP) or maleic anhydride‐grafted polypropylene (MAPP) were prepared by melt‐mixing with different contents of cellulose from 0 to 60 wt %. Ternary composites of cellulose with PP and MAPP were also prepared to investigate the effects of MAPP as a compatibilizer between cellulose and PP. Scanning electron microscopy revealed that the addition of MAPP generates strong interactions between a PP matrix and cellulose fibers: All cellulose fibers are encapsulated by layers of the matrix and connected tightly within the matrix. Thus, the tensile strength and Young's modulus of MAPP‐containing composites increase with an increase in MAPP and cellulose content, in contrast to the decrease in tensile strength of a PP‐based binary composite with an increase in cellulose. Cellulose fibers act as a nucleating agent for the crystallization of PP, which is promoted by the addition of MAPP through an increase of the crystallization temperature of PP in the composite. Accordingly, both cellulose and MAPP facilitate the thermooxidative stability of PP composites in the following order: MAPP/cellulose > PP/MAPP/cellulose > PP/cellulose > PP. Relative water absorption increases with an increase in cellulose content, decreasing with the addition of MAPP. MAPP‐containing cellulose composites have high potential for applications as environmentally friendly materials. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 337–345, 2003     

Composition,tensile properties,and dispersion of polypropylene composites reinforced with viscose fibers

The reinforcement mechanics of viscose‐fiber‐reinforced polypropylene (PP) composites were studied. The effect of the coupling agent, maleated polypropylene (MAPP), was of special interest. The fibers, coupling agent, and PP were extruded and injection‐molded. The composition, mechanical properties, fracture morphology, and dispersion of the composites were examined. Thermogravimetric analysis showed that the fiber content in the tensile specimens varied slightly with the sample location; however, the differences in the values were within 1.0%. Scanning electron microscopy images of the fracture surfaces of the composites showed that the surfaces of the composites without MAPP were covered with fibers pulled out from the matrix. A lack of adhesion further appeared as a cracked matrix–fiber interface. A new scanning thermal microscopy method, microthermal analysis, was used to study the dispersion of the fibers in the composites. Local thermal analyses gave further information about the location of the fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2676–2684, 2004     

Effect of hydrocarbon resin on the morphology and mechanical properties of isotactic polypropylene/clay composites

The article reports an investigation of the effect of a hydrocarbon resin, Necirés TR100, on the structure, morphology, and properties of two isotactic polypropylene/clay composites. The clays are Dellite HPS, a purified montmorillonite, and Dellite 67G, a purified and modified montmorillonite with a high content of quaternary ammonium salt. Necirés TR100 contains hydroxyl and acid groups, which were expected to interact during the melt mixing with the polar surface of the clays to have intercalation with Dellite HPS and/or exfoliation of Dellite 67G, which is already intercalated by the quaternary ammonium salt. The morphological results indicate that the composite isotactic polypropylene/Dellite HPS presents large and coarse clay domains, whereas the composite isotactic polypropylene/Dellite 67G presents a better distribution of the clay clusters, although the presence of some clay domains of a few μm are also detected. Although results from Wide Angle X‐ray Diffraction have indicated that Necirés TR100 has no effect on the layers distance of Dellite HPS and Dellite 67G its addition produces composites with clay particles homogenously distributed in the polyolefin matrix, better tensile properties (higher values of Young's modululs and elongation to break) and decrease of permeability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cellulose/polypropylene composites: Influence of the molecular weight and concentration of oxidatively degraded and maleated polypropylene compatibilizers on tensile behavior

To improve interactions between fibrous cellulose (FC) and polypropylene (PP), oxidatively degraded polypropylene (DgPP) and maleated polypropylene (MAPP) were studied as compatibilizers. Both compatibilizers had the same mechanism, using esterification between the OH group in FC and the reactive (γ‐lactone, acid, and maleic anhydride) groups in the compatibilizers. However, the adhesion style with the ester bond was considerably different because of the arrangements of the reactive groups. DgPP had reactive groups at the polymer chain end, and the tensile behavior of the FC/PP/DgPP composite exhibited comparatively ductile behavior. However, MAPP had inner reactive groups, and the tensile behavior of the FC/PP/MAPP composite was quite brittle. Observation of these fracture surfaces suggested that the adhesion performance of the interface between FC and PP was strongly influenced by the arrangements of the reactive group. In addition, the performance was influenced by the molecular weight of DgPP and by the content of maleic anhydride groups in MAPP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Gas turbine environment effect on morphology and mechanical properties of pultruded composite

The effect of gas turbine lubricant oil soaking, thermal cycling and their combination on morphology and tension and flexure properties of pultruded composite was studied. Two types of lubricant oils were used: Mil‐L‐7808 and Mil‐L‐23699. Composite samples were oil soaked for 720 h and microscopic analysis and mechanical tests were conducted. Samples were thermal cycled for 600 cycles (RT to 315°C) and measured tension and flexure properties. Samples were oil soaked, thermal cycled and then tested. Results of these three groups of environmentally aged samples were compared with non‐aged samples. The significance of aging effect is discussed in the article. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Exploring a highly dispersible silica–elastomer composite for tire applications

In this article, we provide an extensive analyses of various properties that are required for tire tread based on developed highly dispersible (HD) silica‐filled epoxidized natural rubber composites. Silica in an HD form has become a staple filler in tire tread applications because of its inherent advantages. In this study, epoxidized natural rubber with 25 mol % epoxide (ENR 25) and natural rubber were mixed with two different types of HD silica for superior reinforcement. A standard tire tread formulation was used as the base compound. The magic triangle properties were conspicuously influenced by the viscoelastic characteristics of the vulcanizates. The introduction of polar rubber (ENR 25) into the HD silica greatly improved rheological, physicomechanical, bound rubber content, and dynamic mechanical properties, and this led to a better, fuel‐efficient tire. We successfully achieved this, even in the absence of a silane coupling agent. ENR 25 played an imperative role in showing an extraordinary rubber–filler interactions and was primarily responsible for these observations. In this study, we explored the HD silica dispersion with transmission electron microscopy observations. Morphological studies revealed well‐dispersed HD silica with the formation of a rubber–filler network. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43531.     

Bamboo fiber reinforced polypropylene composites and their mechanical,thermal, and morphological properties

Short bamboo fiber reinforced polypropylene composites were prepared by incorporation of various loadings of chemically modified bamboo fibers. Maleic anhydride grafted polypropylene (MA‐g‐PP) was used as compatibilizer to improve fiber–matrix adhesion. The effects of bamboo fiber loading and modification of the resin on the physical, mechanical, thermal, and morphological properties of the bamboo reinforced modified PP composites were studied. Scanning electron microscopy studies of the composites were carried out on the interface and fractured surfaces. Thermogravimetric analysis and IR spectroscopy were also carried out. At 50% volume fraction of the extracted bamboo fiber in the composites, considerable increase in mechanical properties like impact, flexural, tensile, and thermal behavior like heat deflection temperature were observed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology,deformation behavior and thermomechanical properties of polypropylene/maleic anhydride grafted polypropylene/layered silicate nanocomposites

Nanocomposites polypropylene (PP) with 3 and 7 wt % of clay were prepared by melt mixing. Four types of maleic anhydride grafted PP (MAPP) in broad range of MA groups content (0.3–4 wt %) and molecular weights (MW) were used as polar compatibilizers. The effect of the MAPP kind on both the clay dispersion and miscibility with PP was studied. The mixed intercalated/exfoliated morphologies of nanocomposites in the presence of all studied compatibilizers were revealed by XRD and TEM. The oligomer compatibilizer with 4 wt % of MA groups increases the intercalation ability of polymer into clay galleries but this one has limited miscibility with PP and worsens crystalline structure of polymer matrix. The MAPPs with 0.3–1.3% of MA are characterized by the lower intercalation ability but well cocrystallize with PP. Maximum reinforcing effect is attained using high MW MAPP with 0.6% MA and for nanocomposite with 7 wt % (3.8 vol %) of clay it averages almost 1.7 times relative to neat PP and 1.3 times relative to noncompatibilized composite. Dynamic storage moduli of nanocomposites compatibilized by MAPPs with 0.3–1.3% of MA containing 7 wt % of clay increase up to 1.4–1.5 around 30–75°C and over the whole temperature range remain higher compared with both neat PP and uncompatibilized composite. On the contrary, the oligomer MAPP with 4 wt % of MA groups decreases the thermal–mechanical stability of nanocomposite at high temperature compared with both PP and uncompatibilized composites. The study of nanocomposites flammability showed that creating complex composites containing both layered silicate and relatively small amount of magnesium hydroxide can be a successful approach to reduce the combustibility of PP‐based nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Engineering properties of compatibilized polypropylene/liquid crystalline polymer blends

Polypropylene (PP) and Vectra A950, a thermotropic liquid crystalline polymer (LCP), blends were prepared in a single‐screw extruder with the variation in Vectra A950 content in presence of fixed amount (2%, with respect to PP and LCP mixture as a whole) of ethylene‐acrylic acid (EAA) copolymer as a compatibilizer. Mechanical analysis of the compatibilized blends within the range of LCP incorporations under study (2–10%) indicated pronounced improvement in the moduli, ultimate tensile strength (UTS), and hardness. Fourier transform infrared (FTIR) spectroscopy studies revealed the presence of strong interaction through H‐bonding between the segments of Vectra A950 and the compatibilizer EAA. Morphological studies performed by scanning electron microscopy (SEM) manifested the development of fine fibrillar morphology in the compatibilized PP/Vectra A950 blends, which had large influence on the mechanical properties. Differential scanning calorimetry studies showed an initial drop of the melting point of PP in the presence of EAA followed by enhancement of the same in presence of Vectra A950. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP. Rheological studies showed that a very small quantity of Vectra A 950 was capable of reducing the melt viscosity of PP particularly in the lower shear rate region and hence facilitated processibility of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dynamic mechanical properties,crystallization behaviors,and low‐temperature performance of polypropylene random copolymer composites

In this study, polypropylene random copolymer (PPR) composites were prepared by the addition of either three kinds of thermoplastic rubber (TPR) modifiers (types 2088A, 2095, and 2096) or an ethylene–octene copolymer (POE)/high‐density polyethylene (HDPE; 2 :1 w/w) blend. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and dynamic mechanical analysis were used to characterize the crystallization behaviors and dynamic mechanical properties of the PPR composites. The results indicated that PPR/POE/HDPE and PPR/TPR2088A had better comprehensive mechanical properties, especially the low‐temperature toughness among all of the samples. The obtained PPR/POE/HDPE blends showed a high toughness and good stiffness in the temperature interval from ?10 to 23°C with the addition of only 10 wt % POE/HDPE. When the temperature continued to fall below ?10°C, the PPR/TPR2088A composites exhibited a better impact toughness without a loss of too much stiffness. The good low‐temperature toughness of those two composites was attributed to both the decrease in the crystallinity and the uniform dispersion, obvious interfacial adhesion, and cavitation ability of POE/HDPE and TPR2088A in the PPR matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42960.     

Interfacial properties of highly oriented coextruded polypropylene tapes for the creation of recyclable all‐polypropylene composites

The creation of highly oriented, coextruded polypropylene (PP) tapes allows the production of novel, wholly thermoplastic, recyclable “all‐polypropylene” (all‐PP) composites, which possess both a large temperature processing window (>30°C) and a high volume fraction of reinforcement phase (highly oriented PP tapes: >90%). This large processing window is achieved by using coextruded, highly drawn PP tapes. To achieve coherent all‐PP composites the interfacial characteristics following consolidation must be understood. This article investigates the interfacial characteristics of these coextruded tapes by using microcomposite models to create interfaces between tapes of varying draw ratios, drawing temperatures, skin/core ratios, and skin layer thicknesses. The tape drawing parameters are seen to control the interfacial properties in subsequent microcomposite models. The failure mode of these specimens, and hence bond strength, varies with consolidation temperature, and a model is proposed describing and explaining this behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 118–129, 2007     

Melt flow properties,mechanical properties,thermal properties and morphology of polycarbonate/highly branched polystyrene blends

A highly branched polystyrene (HBPS) was synthesized via the copolymerization of 4‐(chloromethyl) styrene with styrene using the self‐condensing atom transfer radical polymerization method. The addition of HBPS as a melt modifier for polycarbonate (PC) was attempted. Melt flow properties, mechanical properties, thermal properties and morphology of the blends were studied. The results showed that a significant drop in the blend viscosity occurs immediately on addition of HBPS. Impact strength, tensile strength and glass transition temperature (T_g) of all the blends have not been significantly reduced compared with those of pure PC. The TGA analyses showed that an initial weight loss temperature of all the blends is above 458 °C and slightly low compared with that of pure PC, but all the blends still have excellent thermal stability. Morphological studies using SEM showed that a two‐phase morphology is characteristic of all the blends, with more or less spherical droplets of the minor HBPS phase dispersed in the continuous PC phase. Copyright © 2006 Society of Chemical Industry     

Lightweight investigation of long chain branching polypropylene/cellulose nanofiber composite foams

Long chain branching polypropylene (LCBPP)/cellulose nanofiber (CNF) composite foams were prepared by short shot foam injection molding method and their morphological, mechanical, and thermal properties were also investigated. The cellular structure of LCBPP/CNF composite foams was improved with weight reduction (WR) ratios increasing. The cell densities of LCBPP/CNF composite foams were dramatically increasing with WR ratios rising. More, the fine and uniform cellular structures were obtained due to the incorporation of CNF. The highest cell density, specific flexural strength, and modulus could achieved 20 × 10³ cell/cm², 65 MPa/(g/cm³) and 2.7 GPa/(g/cm³), respectively. Furthermore, the specific Charpy impact strengths were also higher than the ones of solid samples. At last, the thermal insulation properties were discussed accordingly.     

Nano‐crystalline cellulose,chemical blowing agent,and mold temperature effect on morphological,physical/mechanical properties of polypropylene

Polypropylene (PP)/nano‐crystalline cellulose (NCC) composites and foams were produced through extrusion compounding combined with injection molding. From the samples produced, a complete morphological, physical, and mechanical analysis was performed to study the effect of NCC concentration (0–5wt %), foaming agent content (0 to 2wt %) and mold temperature (30°C and 80°C). NCC was very effective to reduce cell size (42–71%) and increase cell density (5–37 times) of the foams, while slightly increasing the overall density (2–7%). The results showed that NCC addition increased the specific tensile modulus (15–22%), specific tensile strength (1–14%) and specific flexural modulus (13–26%) of PP, but decreased specific impact strength (10–20%) and specific elongation at break (50–96%). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42845.     

A compatibilized composite of recycled polypropylene filled with cellulosic fiber from recycled corrugated paper board: Mechanical properties,morphology, and thermal behavior

This article deals with the feasibility of using recycled corrugated paper board (rPF) as the reinforcing material for recycled plastics. The composites of recycled polypropylene (rPP) and rPF were prepared by extrusion compounding and injection molding, and the rPP/rPF composites compatibilized by maleic anhydride grafted PP (PP‐g‐MA), maleic anhydride grafted ethylene‐1‐octene copolymer (POE‐g‐MA), and maleic anhydride grafted styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA) were also prepared. The crystallization and melting behavior, mechanical properties, thermal stability, and morphology of these composites were studied. The results indicated that rPF promoted the crystallization, enhanced the strength and toughness of rPP/rPF composites to some extent while decreased thermal stability at the same time. PP‐g‐MA and POE‐g‐MA improved the dispersion and interface adhesion of rPF, and further upgraded the mechanical properties and vicat softening temperatures. Among these compatibilizers, PP‐g‐MA was most favorable to the strength improvement while POE‐g‐MA was most favorable to the toughness improvement. As for SEBS‐g‐MA, it had no obvious modification effect. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011