Mechanical properties of biodegradable composites from poly lactic acid (PLA) and microcrystalline cellulose (MCC)

Biodegradable composites were prepared using microcrystalline cellulose (MCC) as the reinforcement and polylactic acid (PLA) as a matrix. PLA is polyester of lactic acid and MCC is cellulose derived from high quality wood pulp by acid hydrolysis to remove the amorphous regions. The composites were prepared with different MCC contents, up to 25 wt %, and wood flour (WF) and wood pulp (WP) were used as reference materials. Generally, the MCC/PLA composites showed lower mechanical properties compared to the reference materials. The dynamic mechanical thermal analysis (DMTA) showed that the storage modulus was increased with the addition of MCC. The X‐ray diffraction (XRD) studies on the materials showed that the composites were less crystalline than the pure components. However, the scanning electron microscopy (SEM) study of materials showed that the MCC was remaining as aggregates of crystalline cellulose fibrils, which explains the poor mechanical properties. Furthermore, the fracture surfaces of MCC composites were indicative of poor adhesion between MCC and the PLA matrix. Biodegradation studies in compost soil at 58°C showed that WF composites have better biodegradability compared to WP and MCC composites. The composite performances are expected to improve by separation of the cellulose aggregates to microfibrils and with improved adhesion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2014–2025, 2005     

Influence of clay modification on the reinforcement of vinyl‐terminated polydimethylsiloxane networks

A novel method was attempted to reinforce a vinyl‐terminated polydimethylsiloxane (PDMS) with two commercially available clays, sodium montmorillonite and Cloisite^® 25A. The two clays were functionalized with bis(3‐triethoxysilylpropyl)tetrasulfide (TESPT) to prepare Na⁺MMTS₄ and C25AS₄, respectively. Incorporation of the tetrasulfide group‐containing clays, especially Na⁺MMTS₄, was found to be effective for the enhancement of the interfacial interaction between PDMS and the clays by way of a plausible chemical reaction between the tetrasulfide groups (TSS) and the vinyl‐terminated PDMS. Compounding of PDMS with the TESPT‐modified clays improved the mechanical properties significantly. In particular, the elongation at break of PDMS/Na⁺MMTS₄ composite was almost twice as high as that of neat PDMS, even if the silicate layers were not fully exfoliated in the PDMS matrix. The tear strength of PDMS was also improved greatly as a result of the incorporation of Na⁺MMTS₄. According to toluene swelling test results, the crosslinking density of the composites was lower than that of neat PDMS, indicating that the improved mechanical properties of the composites arise from enhanced compatibility between the constituents and not from increased crosslinking density. Copyright © 2009 Society of Chemical Industry     

Novel synergistic flame‐retardant system of Mg–Al–Co–LDHs/DPCPB for ABS resins

Acrylonitrile‐butadiene‐styrene (ABS) resins are widely used in many sectors of the industry due to excellent mechanical properties, low temperature resistance, heat resistance, and chemical resistance. However, its flammability constitutes a key limitation in their applications. Consequently, development of flame‐retarding ABS resins is imperative. Herein, we report a novel synergistic system composed of Mg–Al–Co–layered double hydroxides (LDHs) prepared via a co‐precipitation method, and [4‐(diphenoxy‐phosphorylamino)‐6‐phenyl‐[l,3,5] triazin‐2‐y1]‐phosphoramidic acid diphenyl ester (DPCPB), a novel intumescent flame retardant. The properties of the as‐prepared LDHs/DPCPB/ABS composites are evaluated using standard combustion performance tests including limiting oxygen index (LOI) and vertical burning test (UL‐94). Novel ABS resins with the composition of ABS/DPCPB = 100/25 and ABS/DPCPB/LDHs = 100/2l/4 exhibit higher LOIs, 23.9 and 24.7, respectively, compared to 18.1 for the pure ABS. Meanwhile, they meet the V‐2 and A‐1 level, respectively, in UL‐94 tests. Moreover, the prepared composites exert flame‐retarding effects in gas phase and condensed phase simultaneously. Our results reveal synergistic effects between Mg–Al–Co–LDHs and DPCPB for the flame retardation of ABS resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46319.     

Preparation and properties of L‐lactide‐grafted sisal fiber–reinforced poly(lactic acid) composites

Pretreatment of the sisal fiber (SF) grafting with L‐lactide (LA) monomer via a ring‐opening polymerization catalyzed by a Sn(II)‐based catalyst was performed to improve the interfacial adhesion between SF and poly (lactic acid) (PLA). Biocomposites from LA‐grafted SF (SF‐g‐LA) and PLA were prepared by compression molding with fiber weight fraction of 10, 20, 30, and 40%, and then were investigated in contrast with alkali‐treated sisal fiber (ASF) reinforced PLA composites and untreated SF reinforced PLA composites. PLA composites reinforced by half‐and‐half SF‐g‐LA/untreated SF (half SF‐g‐LA) were prepared and studied as well, considering the disadvantages of SF‐g‐LA. The results showed that both the tensile properties and flexural properties of the SF‐g‐LA reinforced PLA composites were improved noticeably as the introduction of SF‐g‐LA, compared with pure PLA, untreated SF reinforced PLA composites and ASF reinforced PLA composites. The mechanical properties of the half SF‐g‐LA reinforced PLA composites were not worse, even better in some aspects, than the SF‐g‐LA reinforced PLA composites. Fourier transform infrared analysis and differential scanning calorimetry analysis exhibited that both the chemical composition and crystal structure of the SFs changed after LA grafting. In addition, the fracture surface morphology of the composites was studied by scanning electron microscopy. The morphological studies demonstrated that a better adhesion between LA‐grafted SF and PLA matrix was achieved. POLYM. COMPOS., 37:802–809, 2016. © 2014 Society of Plastics Engineers     

Polylactide toughening with epoxy‐functionalized grafted acrylonitrile–butadiene–styrene particles

Glycidyl methacrylate functionalized acrylonitrile–butadiene–styrene (ABS‐g‐GMA) particles were prepared and used to toughen polylactide (PLA). The characteristic absorption at 1728 cm^?1 of the Fourier transform infrared spectra indicated that glycidyl methacrylate (GMA) was grafted onto the polybutadiene phase of acrylonitrile–butadiene–styrene (ABS). Chemical reactions analysis indicated that compatibilization and crosslinking reactions took place simultaneously between the epoxy groups of ABS‐g‐GMA and the end carboxyl or hydroxyl groups of PLA and that the increase of GMA content improved the reaction degree. Scanning electron microscopy results showed that 1 wt % GMA was sufficient to satisfy the compatibilization and that ABS‐g‐GMA particles with 1 wt % GMA dispersed in PLA uniformly. A further increase of GMA content induced the agglomeration of ABS‐g‐GMA particles because of crosslinking reactions. Dynamic mechanical analysis testing showed that the miscibility between PLA and ABS improved with the introduction of GMA onto ABS particles because of compatibilization reactions. The storage modulus decreased for the PLA blends with increasing GMA content. The decrease in the storage modulus was due to the chemical reactions in the PLA/ABS‐g‐GMA blends, which improved the viscosity and decreased the crystallization of PLA. A notched impact strength of 540 J/m was achieved for the PLA/ABS‐g‐GMA blend with 1 wt % GMA, which was 27 times than the impact strength of pure PLA, and a further increase in the GMA content in the ABS‐g‐GMA particles was not beneficial to the toughness improvement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modification of poly(lactic) acid by reactive extrusion and its melt blending with acrylonitrile–butadiene–styrene

Poly(lactic) acid (PLA) is a biodegradable polymer that has attracted interest as a potential substitute for some thermoplastic polymers. However, its advanced brittleness at room temperature represents one of the major drawbacks for its general use. In this work, PLA was modified by reactive extrusion (PLA_REx) to enhance the rheological behaviour and to limit its degradation. The modified material was melt blended with acrylonitrile–butadiene–styrene (ABS), and the resultant morphology, rheological, thermo‐mechanical and fracture behaviour were analysed. Since PLA does not have reasonable compatibility with ABS, maleic‐anhydride‐grafted ABS (ABS‐g‐Ma) was used as compatibilizer. The morphology of the PLA_REx/ABS samples resulted in the formation of small ABS rods in the matrix. The presence of maleic anhydride contributed to reducing the interfacial energy of the blends and to obtaining finer micro‐domains of the ABS‐rich phase in the PLA_REx matrix. In the compatibilized blends, the presence of elongated ABS‐rich phases opposed free crack propagation and contributed to the increase in fracture energy in comparison to neat PLA. © 2020 Society of Chemical Industry     

Crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites

The isothermal crystallization behavior of α‐cellulose short‐fiber reinforced poly(lactic acid) composites (PLA/α‐cellulose) was examined using a differential scanning calorimeter and a petrographic microscope. Incorporating a natural micro‐sized cellulose filler increased the spherulite growth rate of the PLA from 3.35 μm/min for neat PLA at 105°C to a maximum of 5.52 μm/min for the 4 wt % PLA/α‐cellulose composite at 105°C. In addition, the inclusion of α‐cellulose significantly increased the crystallinities of the PLA/α‐cellulose composites. The crystallinities for the PLA/α‐cellulose composites that crystallized at 125°C were 48–58%, higher than that of the neat PLA for ～13.5–37.2%. The Avrami exponent n values for the neat and PLA/α‐cellulose composites ranged from 2.50 to 2.81 and from 2.45 to 3.44, respectively, and the crystallization rates K of the PLA/α‐cellulose composites were higher than those of the neat PLA. The activation energies of crystallization for the PLA/α‐cellulose composites were higher than that of the neat PLA. The inclusion of α‐cellulose imparted more nucleating sites to the PLA polymer. Therefore, it was necessary to release additional energy and initiate molecular deposition. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Bleached extruder chemi‐mechanical pulp fiber‐PLA composites: Comparison of mechanical,thermal, and rheological properties with those of wood flour‐PLA bio‐composites

An environmentally friendly bleached extruder chemi‐mechanical pulp fiber or wood flour was melt compounded with poly(lactic acid) (PLA) into a biocomposite and hot compression molded. The mechanical, thermal, and rheological properties were determined. The chemical composition, scanning electron microscopy, and Fourier transform infrared spectroscopy results showed that the hemicellulose in the pulp fiber raw material was almost completely removed after the pulp treatment. The mechanical tests indicated that the pulp fiber increased the tensile and flexural moduli and decreased the tensile, flexural, and impact strengths of the biocomposites. However, pulp fiber strongly reinforced the PLA matrix because the mechanical properties of pulp fiber‐PLA composites (especially the tensile and flexural strengths) were better than those of wood flour‐PLA composites. Differential scanning calorimetry analysis confirmed that both pulp fiber and wood flour accelerated the cold crystallization rate and increased the degree of crystallinity of PLA, and that this effect was greater with 40% pulp fiber. The addition of pulp fiber and wood flour modified the rheological behavior because the composite viscosity increased in the presence of fibers and decreased as the test frequency increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44241.     

Development of lightweight thermoplastic composites based on polycarbonate/acrylonitrile–butadiene–styrene copolymer alloys and recycled carbon fiber: Preparation,morphology, and properties

Thermoplastic composites of polycarbonate (PC)/acrylonitrile–butadiene–styrene copolymer (ABS) alloys reinforced with recycled carbon fiber (RCF) were prepared by melt extrusion through a twin‐screw extruder. The RCF was first cleaned and activated with a concentrated solution of nitric acid and was then surface‐coated with diglycidyl ether of bisphenol A as a macromolecular coupling agent. Such an approach is effective to improve the interfacial bonding between the fibers and the PC/ABS matrix. As was expected, the reinforcing potential of the RCF was enhanced substantially, and furthermore, the mechanical properties, heat distortion temperature, and thermal stability of PC/ABS alloys were significantly improved by incorporating this surface‐treated RCF. The composites also obtained a reduction in electrical resistivity. The morphologies of impact fracture surfaces demonstrated that the RCF achieved a homogeneous dispersion in the PC/ABS matrix due to good interfacial adhesion between the fibers and the matrix. In addition, the introduction of RCF into PC/ABS alloys also resulted in an increase in the storage moduli of the composites but a decrease in the loss factors. It is prospective that, with such good performance in mechanical data, heat resistance, and electrostatic discharge, the RCF‐reinforced PC/ABS composites exhibit a potential application in industrial and civil fields as high‐performance and lightweight materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flexural,compression, chemical resistance,and morphology studies on granite powder‐filled epoxy and acrylonitrile butadiene styrene‐toughened epoxy matrices

Granite powder is an inexpensive material that can reduce the overall cost of a composite if used as a filler in epoxy and acrylonitrile butadiene styrene (ABS)‐toughened epoxy matrices. Epoxy and ABS‐toughened epoxy resins filled with granite powder were cast into sheets. To enhance the properties of these composites, granite powder was treated with triethoxymethyl silane coupling agent. Flexural properties, compression properties, chemical resistance, and morphology of these composites were studied. The filler used varied from 0 to 60 wt %. Composites consisting of ABS‐toughened epoxy with treated granite powder were found to be superior in mechanical properties to composites with treated and untreated granite powder. Composites with 50 wt % of granite powder was found to have maximum mechanical properties in all cases. All the three composites, i.e., untreated, treated and ABS toughened composites showed good resistance toward, acids, alkalis, and solvents. Treating granite powder with silane coupling agent enhances its mechanical properties and improves the interfacial bond between granite powder and the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 171–177, 2007     

Characterization of lignocellulosic–poly(lactic acid) reinforced composites

The effects of adding poly(lactic acid) (PLA) to the physical strength of paper test sheets prepared from three unbleached loblolly pine kraft pulps with different amounts of lignin and an aspen bleached chemothermomechanical pulp were studied. The physical strength studies demonstrated that relatively low levels of PLA addition (0.5–4.0%) could dramatically improve the tensile and burst strength properties as a function of the amount of PLA added. Hot pressing the test sheets was shown to be an important treatment for enhancing the strength properties. An analysis of untreated and PLA‐treated hot‐pressed test sheets by atomic force microscopy indicated that the addition of PLA markedly altered the surface properties of the sheets. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1346–1349, 2006     

Thermomechanical properties of poly(lactic acid) films reinforced with hydroxyapatite and regenerated cellulose microfibers

Novel composite films constituted of poly(lactic acid) (PLA), hydroxyapatite (HAp), and two types of regenerated cellulose fillers—particulate and fibrous type—were produced by melt extrusion in a twin‐screw micro‐compounder. The effect of the film composition on the tensile and dynamic mechanical behavior and the HAp dispersion in the PLA matrix were investigated thoroughly. Appearance of crazed regions and prevention of HAp aggregation in the PLA matrix were elucidated in the composites with up to 15 wt % particulate cellulose content, which was the main reason for only slight reduction in the tensile properties, and consequently trivial degradation of their pre‐failure energy absorption as compared to neat PLA films. Superior dynamical energy storage capacities were obtained for the particulate cellulose modified composites, while their fibrous counterparts had not as good properties. Additionally, the anisotropic mechanical behavior obtained for the extruded composites should be favorable for use as biomaterials aimed at bone tissue engineering applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40911.     

Electromagnetic interference shielding effectiveness and mechanical sliding behavior for electroless nickel/phosphorous–poly(tetrafluoroethylene) codeposition on carbon fiber/acrylonitrile–butadiene–styrene composites

Poly(tetrafluoroethylene) (PTFE) powders were mounted on an electroless nickel/phosphorous (Ni/P) film on the surface of a carbon fiber by an electroless codeposition method. This type of carbon fiber filler, denoted FENCF, was then compounded with acrylonitrile–butadiene–styrene (ABS) for use in electromagnetic interference shielding. For the suspension of the PTFE powders, a surfactant was used. Although the adhesion between the electroless Ni/P–PTFE films and the fiber was reduced, the PTFE powders on the surface of FENCF reduced the torque values when compounded into the ABS matrix because of a self‐lubricating effect. The two‐step FENCF composites exhibited particularly significant advantages. The torque values for the two‐step FENCF/ABS composites were about one‐half of those for carbon fiber/ABS composites in compounding processes; in addition, the former had an average mean fiber length almost 2.5 times that of the latter. The multiyield phenomena in stress–strain curves of FENCF/ABS composites implied that the PTFE powders mounted on Ni/P films slid during stress–strain action. The electromagnetic interference shielding effectiveness of FENCF/ABS composites did not decrease significantly even though the PTFE powders formed a discontinuous phase on the electroless Ni/P films. The mechanical properties of FENCF composites were enhanced because of the larger fiber length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1661–1668, 2002     

Cellulose fiber‐reinforced polylactic acid

Polymer composites from polylactic acid (PLA) and two types of cellulose fibers obtained either by acid hydrolysis of microcrystalline cellulose (HMCC) or by mechanical disintegration of regenerated wood fibers (MF) were prepared and characterized. To enhance the compatibility of the cellulose fibers with PLA matrix, a surface treatment based on 3‐aminopropyltriethoxysilane (APS) was performed. The Fourier Transform Infrared (FTIR) spectroscopy was used to determine the chemical groups involved in the surface modification reaction. The silanization treatment resulted in different modifications on both types of cellulose fibers because of their different structural and morphological characteristics. The composites were prepared by incorporating 2.5% of the treated or untreated HMCC and MF into a PLA matrix using a melt‐compounding technique. An improved adhesion between the two phases of the composite materials was observed by scanning electron microscopy thanks to treatment. The dynamic mechanical thermal analyses showed that both untreated and silane treated fibers led to an improvement of the storage modulus of PLA in the glassy state. A higher enhancement of the storage modulus in the case of PLA/HMCC composites than the composites containing MF was obtained as a result of the high aspect ratio of these fibers which allows better matrix‐to‐filler stress transfer. Furthermore, the storage modulus of PLA composites was enhanced by silanization even at higher temperatures especially after thermal treatment. The cellulose fibers addition in PLA matrix modified significantly the relaxation phenomenon as observed in tan δ curves, emphasizing strongly modified molecular mobility of PLA macromolecules and crystallization changes. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.     

Maleated high oleic sunflower oil‐treated cellulose fiber‐based styrene butadiene rubber composites

Surface treatment of cellulose fibers was performed with maleated high oleic sunflower oil (MSOHO). The MSOHO‐treated cellulose fibers and unmodified cellulose fibers were dispersed in styrene butadiene rubber (SBR) using a two roll mill. Vapor grown carbon nanofibers (VGCNF) were also incorporated at only one parts per hundred rubber (phr) in unmodified cellulose fibers/SBR composites. The curing characteristics, mechanical properties, and water absorption of the resulting composites were determined. MSOHO‐treated fibers completed curing at much slower rate and also decreased the cure density of composites, compared to unmodified fibers. In contrast, the combination of VGCNF and unmodified cellulose fibers accelerated the SBR curing process, but reduced the cure density. MSOHO treatment improved the dispersion of the fibers in the SBR, which resulted in improved mechanical properties of composites. The composite incorporating 1 phr VGCNF and 15 phr unmodified cellulose fibers showed the greatest increase in tensile strength as compared with neat SBR. POLYM. COMPOS. 37:1113–1121, 2016. © 2014 Society of Plastics Engineers     

Effects of in‐situ functionalization of carbon nanotubes with bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES) on properties of epoxidized natural rubber–carbon nanotube composites

Composites of carbon nanotubes (CNT) and epoxidized natural rubber (ENR) were prepared by in‐situ functionalization of CNT with two alternative silane coupling agents: bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES). The reactions of ENR molecules with the functional groups on CNT surfaces and with the silane molecules were characterized by Fourier transform infrared. Furthermore, cross‐link density, relaxation behaviors, curing, mechanical, electrical, and morphological properties of pristine ENR and the ENR composites were investigated. Very low percolation thresholds, at CNT concentrations as low as 1 phr, were observed in the ENR–CNT and the ENR–CNT–TESPT composites. This might be attributed to improvements in the chemical linkages between ENR molecules and functional groups on CNT surfaces that led to a homogenous dispersion of CNTs in the ENR matrix, with loose CNT agglomerates. POLYM. ENG. SCI., 55:2500–2510, 2015. © 2015 Society of Plastics Engineers     

Study of the influence of adding styrene–ethylene/butadiene–styrene in acrylonitrile–butadiene–styrene and polyethylene blends

This work studies the recovery of two grades of acrylonitrile–butadiene–styrene (ABS) contaminated with low‐density polyethylene (LDPE), by adding styrene–ethylene/butadiene–styrene (SEBS). To simulate contaminated ABS, virgin ABS was mixed with 1, 2, 4, and 8% of LDPE and then extruded at 220°C. After this, the ABS with the highest percentage of LDPE (8%) was mixed with 1, 2, 4, and 8% of SEBS and then extruded. Different blends were mechanically, rheologically, optically, and dimensionally characterized to study how different percentages of LDPE and SEBS modify their properties. The results obtained show how the tensile strength, Young modulus, elongation, and impact strength linearly decrease as the LDPE amount increases, for both natural and black ABS. Through the addition of SEBS to contaminated ABS, it is possible to improve its impact strength and elongation values nearly to those of virgin ABS. However, its tensile strength and Young modulus show no improvement, and even show a slight reduction. Regarding the rheological properties, the LDPE contamination in ABS causes a remarkable decrease in viscosity, and adding SEBS to the blend lowers its viscosity even further for both natural and black grades. This reduction is not a negative aspect, but rather quite the reverse, as the more fluid the material, the easier the mold injection process becomes. POLYM. ENG. SCI., 54:1313–1324, 2014. © 2013 Society of Plastics Engineers     

Synthesis and characterization of polypropylene reinforced with cellulose I and II fibers

Recently, cellulose fiber–thermoplastic composites have played an important role in some applications. Plastics reinforced with cellulose and natural fibers have been widely studied. However, composites with regenerated cellulose have rarely been investigated. In this study, the lyocell fiber of Lenzing AG (cellulose II) and its raw material a bleached hardwood pulp (cellulose I) were used as reinforcement materials. The mechanical and thermal properties of polypropylene (PP) reinforced with pulp and lyocell fibers were characterized and compared with regard to the content of the fiber and the addition of maleated polypropylene (MAPP). PPs with cellulose I or II as a reinforcement material had similar mechanical properties. However, when MAPP was used as coupling agent, the mechanical properties of the composites were different. The crystallinity of the composites were determined by differential scanning calorimetry. Cellulose I (pulp) promoted the crystallization of PP, whereas cellulose II did not. MAPP reduced this effect in cellulose I fibers, but it induced crystallization when cellulose II (lyocell) was used as a reinforcement material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 364–369, 2006     

Mechanical and thermal properties of poly(acrylonitrile–butadiene–styrene) copolymer reinforced with potassium titanate whiskers

Potassium titanate (K₂Ti₆O₁₃) whisker treated with tetrabutyl orthotitanate was used to improve the mechanical and thermal properties of the poly(acrylonitrile–butadiene–styrene) (ABS) copolymer. The composites were prepared in a twin‐screw extruder followed by injection molding. Static tensile measurements showed that both the modulus and breaking stress of ABS/K₂Ti₆O₁₃ composites increase considerably with increasing whisker content; the strain at break of ABS was almost unaffected by the incorporation of a whisker content up to 15 wt %. Izod impact tests indicated that the composites showed a decrease in the impact strength with increasing whiskers content. Thermogravimetric analysis showed that the K₂Ti₆O₁₃ whisker additions have little effect on the thermooxidative stability of ABS. Scanning electron microscopic observations revealed that the whiskers were aligned along the melt‐flow direction in the thin surface layer, whereas the whiskers were oriented randomly as well as perpendicular to the injection direction in the thick core region of the composites. The Tsai–Halpin equation was used to evaluate the moduli of the ABS/K₂Ti₆O₁₃ composites. The theoretical calculations generally correlated well with the experiment data by assuming K₂Ti₆O₁₃ whiskers to have an aspect ratio of 12. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2985–2991, 1999     

Effect of surface modifiers and surface modification methods on properties of acrylonitrile–butadiene–styrene/poly(methyl methacrylate)/nano‐calcium carbonate composites

Nano‐calcium carbonate (nano‐CaCO₃) was used in this article to fill acrylonitrile–butadiene–styrene (ABS)/poly(methyl methacrylate) (PMMA), which is often used in rapid heat cycle molding process (RHCM). To achieve better adhesion between nano‐CaCO₃ and ABS/PMMA, nano‐CaCO₃ particles were modified by using titanate coupling agent, aluminum–titanium compound coupling agent, and stearic acid. Dry and solution methods were both utilized in the surface modification process. ABS/PMMA/nano‐CaCO₃ composites were prepared in a corotating twin screw extruder. Influence of surface modifiers and surface modification methods on mechanical and flow properties of composites was analyzed. The results showed that collaborative use of aluminum–titanium compound coupling agent and stearic acid for nano‐CaCO₃ surface modification is optimal in ABS/PMMA/nano‐CaCO₃ composites. Coupling agent can increase the melt flow index (MFI) and tensile yield strength of ABS/PMMA/nano‐CaCO₃ composites. The Izod impact strength of composites increases with the addition of titanate coupling agent up to 1 wt %, thereafter the Izod impact strength shows a decrease. The interfacial adhesion between nano‐CaCO₃ and ABS/PMMA is stronger by using solution method. But the dispersion uniformity of nano‐CaCO₃ modified by solution method is worse. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013