Tribological properties of bismaleimide composites with surface‐modified SiO2 nanoparticles

In this article, the surface of SiO₂ nanoparticles was modified by silane coupling agent N‐(2‐aminoethyl)‐γ‐aminopropylmethyl dimethoxy silane. The bismaleimide nanocomposites with surface‐modified SiO₂ nanoparticles or unmodified SiO₂ nanoparticles were prepared by the same casting method. The tribological performance of the nanocomposites was studied on an M‐200 friction and wear tester. The results indicated that the addition of SiO₂ nanoparticles could decrease the frictional coefficient and the wear rate of the composites. The nanocomposites with surface‐modified SiO₂ nanoparticles showed better wear resistance and lower frictional coefficient than that with the unmodified nanoparticles SiO₂. The specific wear rate and the steady frictional coefficient of the composite with 1.0 wt % surface‐modified SiO₂ nanoparticles are only 1.8 × 10^?6 mm³/N m and 0.21, respectively. The dispersion of surface‐modified SiO₂ nanoparticles in resin matrix was observed with transmission electron microscope, and the worn surfaces of pure resin matrix and the nanocomposites were observed with scanning electron microscope. The different tribological behavior of the resin matrix and the filled composites should be dependent on their different mechanical properties and wear mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of superhydrophobic nanocomposite fiber membranes by electrospinning poly(vinylidene fluoride)/silane coupling agent modified SiO2 nanoparticles

Superhydrophobic nanocomposite fiber membranes were prepared by blend electrospinning of poly(vinylidene fluoride) (PVDF) mixed with silane coupling agent modified SiO₂ nanoparticles. The nanoparticles were prepared by the sol–gel method, and the average particle diameter was measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The effects of the type of silane coupling agent, such as n‐octyltriethoxysilane, vinyltrimethoxysilane (A‐171), and vinyltriethoxysilane (A‐151), and the mass ratio of the modified silica particles and PVDF on the surface wettability of the composite fiber membrane were investigated. The results indicated that the incorporation of silane coupling agent modified silica particles into the PVDF membrane increased the roughness of the surface and formed micro/nano dual‐scale structure compared to the pristine PVDF membrane, which was responsible for the superhydrophobicity and self‐cleaning property of the nanocomposite fiber membranes. The value of water contact angle (CA) increased with the increase of the content of modified SiO₂ nanoparticles in the nanocomposite membrane, ranging from 149.8° to 160.1° as the mass ratio of modified 170 nm SiO₂ with PVDF matrix increased from 0.5:1 to 5:1, indicating the membrane possesses a superhydrophobic surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44501.     

Chemical surface treatment of ultrahigh molecular weight polyethylene for improved adhesion to methacrylate resins

Ultrahigh molecular weight polyethylene (UHMWPE) has high yield strength and modulus, but is nonpolar and chemically inert. For it to be used as an effective reinforcing agent for composites, methods to make the UHMWPE wettable or capable of reaction with the matrix are critical. In the current work, Spectra 900? (UHMWPE) fibers were surface modified by swelling in p‐xylene with: (1) methylmethacrylate (MMA) monomer; (2) PMMA; (3) camphorquinone (CQ); (4) 3‐methacryloxypropyltrichlorosilane (Cl‐MPS); (5) trimethoxysilyl modified polyethylene, N‐(triethoxysilylpropyl)‐dansylamide (fluorescent silane), or octadecyltrimethoxy silane (OMS), followed by hydrolysis and reaction with Cl‐MPS; and (6) by coating with SiO₂ films followed by reaction with MPS. These modifiers were used to improve wettability and provide sites for chemical interactions with the resin matrix. Beads of resin [60/40 BisGMA‐TEGMA (bis‐phenol A bis‐(2‐hydroxypropyl) methacrylate and tri(ethylene glycol) dimethacrylate)] were light‐cured around the treated fibers and the improvement in adhesion was tested by microbond shear strength (τ) tests. The improvements were comparable to those reported by acid etching and plasma treatments. The OMS, fluorescent silane, and SiO₂/Cl‐MPS treatments yielded the best results, that is fourfold increases in τ compared with untreated fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1564–1572, 2005     

A novel approach to prepare PBT nanocomposites with elastomer‐modified SiO2 particles

Poly(butylenes terephthalate) (PBT)/SiO₂ nanocomposites with uniform dispersion, strong interfacial adhesion, and improved mechanical properties have been prepared by a novel approach. Ethylene‐methyl acrylate‐glycidyl methacrylate (E‐MA‐GMA) elastomer chains were first chemically grafted onto the surface of SiO₂ nanoparticles. Fourier transform infrared spectra result shows that elastomer‐modified SiO₂ nanoparticles exhibit absorption at 2963–2862 cm⁻¹ of the stretching modes of C H, which suggests the reaction between the hydroxyl groups of SiO₂ surface and epoxy groups of E‐MA‐GMA. And the binding energy of Si2p and O1s of the elastomer‐modified SiO₂ shifts to lower binding energy, which further confirms the formation of Si O C bonds. This surface treatment allows SiO₂ nanoparticles homogeneously dispersing in PBT matrix. The morphology with loose aggregates contains networked SiO₂ particles with an interparticle distance ranging from 0 to 30 nm. As a result, the storage modulus and the tensile properties of PBT/E‐MA‐GMA‐SiO₂ nanocomposites are higher than those of pure PBT and PBT with untreated SiO₂. The incorporation of E‐MA‐GMA‐modified SiO₂ particles increases the tensile strength and modulus to 58.4MPa and 2661MPa respectively, which is 8% and 16% higher than those of pure PBT. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Architecture of colloidal crystals constructed by silica hybrid nanoparticles

Silica (SiO₂)‐crosslinked polystyrene (PS) particles possessing photofunctional N,N‐diethyldithiocarbamate (DC) groups on their surface were prepared by the free‐radical emulsion copolymerization of a mixture of SiO₂ (diameter D_n = 192 nm), styrene, divinyl benzene, 4‐vinylbenzyl N,N‐diethyldithiocarbamate (VBDC), and 2‐hydroxyethyl methacrylate with a radical initiator under UV irradiation. In this copolymerization, the inimer VBDC had the formation of a hyperbranched structure by a living radical mechanism. These particles had DC groups on their surface. Subsequently, poly(methyl methacrylate) brushes encapsulated SiO₂ particles were synthesized by the grafting from a photoinduced atom transfer radical polymerization (ATRP) approach of methyl methacrylate initiated by SiO₂‐crosslinked PS particles as a macroinitiator. We constructed the colloidal crystals using these photofunctional particles. Moreover, the SiO₂ particle array of colloidal crystals was locked by radical photopolymerization with vinyl monomer as a matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of a poly(methyl methacrylate) based composite bone cement containing poly(acrylate‐co‐silane) modified hydroxyapatite nanoparticles

The purpose of this study was to study the mechanical properties of poly(methyl methacrylate) (PMMA)‐based bone cement incorporated with hydroxyapatite (HA) nanoparticles after surface modification by poly(methyl methacrylate‐co‐γ‐methacryloxypropyl timethoxysilane) [P(MMA‐co‐MPS)]. PMMA and P(MMA‐co‐MPS) were synthesized via free‐radical polymerization. P(MMA‐co‐MPS)‐modified hydroxyapatite (m‐HA) was prepared via a dehydration process between silane and HA; the bone cement was then prepared via the in situ free‐radical polymerization of methyl methacrylate in the presence of PMMA and P(MMA‐co‐MPS)–m‐HA. Fourier transform infrared (FTIR) spectroscopy, ¹H‐NMR, and gel permeation chromatography were used to characterize the P(MMA‐co‐MPS). Thermogravimetric analysis and FTIR were used as quantitative analysis methods to measure the content of P(MMA‐co‐MPS) on the surface of HA. The effect of the proportion of m‐HA in the PMMA‐based bone cement on the mechanical properties was studied with a universal material testing machine. A 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay was also carried out to determine the cytotoxicity of the composite bone cement. The results showed that the surface modification of HA greatly improved the interaction between the inorganic and organic interfaces; this enhanced the mechanical properties of bone cement for potential clinical applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40587.     

PEGylated hollow pH‐responsive polymeric nanocapsules for controlled drug delivery

Novel pH‐responsive PEGylated hollow nanocapsules (HNCaps) were fabricated through a combination of distillation–precipitation copolymerization and surface thiol–ene ‘click’ grafting reaction. For this purpose, SiO₂ nanoparticles were synthesized using the Stöber approach, and then modified using 3‐(trimethoxysilyl)propyl methacrylate (MPS). Afterward, a mixture of triethyleneglycol dimethacrylate (as crosslinker), acrylic acid (AA; as pH‐responsive monomer) and MPS‐modified SiO₂ nanoparticles (as sacrificial template) was copolymerized using the distillation–precipitation approach to afford SiO₂@PAA core–shell nanoparticles. The SiO₂ core was etched from SiO₂@PAA using HF solution, and the obtained PAA HNCaps were grafted with a thiol‐end‐capped poly(ethylene glycol) (PEG) through a thiol–ene ‘click’ reaction to produce PAA‐g‐PEG HNCaps. The fabricated HNCaps were loaded with doxorubicin hydrochloride (DOX) as a model anticancer drug, and their drug loading and encapsulation efficiencies as well as pH‐dependent drug release behavior were investigated. The anticancer activity of the drug‐loaded HNCaps was extensively evaluated using MTT assay against human breast cancer cells (MCF7). The cytotoxicity assay results as well as superior physicochemical and biological features of the fabricated HNCaps mean that the developed DOX‐loaded HNCaps have excellent potential for cancer chemotherapy. © 2020 Society of Chemical Industry     

Grafting polymerization of 2‐[3‐(2h‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on vinyltriethoxysilane‐treated cotton for the preparation of ultraviolet‐protective fabrics

Vinyltriethoxysilane was used to modify the surface of cotton to provide polymerizable vinyl groups on the fiber surface. An ultraviolet‐absorbing monomer, 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate, was polymerized on the vinyltriethoxysilane‐treated fabric to prepare ultraviolet‐protective cotton. The effects of the amounts of the solvent, silane coupling agent, and 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on the surface morphology and ultraviolet‐protection factor of the treated cotton fabric were investigated. With a suitable process, poly{2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate} was successfully coated onto the fabric, and it significantly reduced ultraviolet transmission through the fabric, resulting in a cotton fabric with excellent ultraviolet‐protection properties. The use of a silane coupling agent helped to ensure a polymer coating with good uniformity and good resistance to washing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Novel synthesis of poly(methyl methacrylate) brush encapsulated silica particles

Silica (SiO₂)‐crosslinked polystyrene (PS) particles possessing photofunctional N,N‐diethyldithiocarbamate (DC) groups on their surface were prepared by the free‐radical emulsion copolymerization of a mixture of SiO₂ (diameter = 20 nm), styrene, divinyl benzene, 4‐vinylbenzyl N,N‐diethyldithiocarbamate (VBDC), and 2‐hydroxyethyl methacrylate with a radical initiator under UV irradiation. In this copolymerization, the inimer VBDC had the formation of a hyperbranched structure by a living radical mechanism. The particle sizes of such core–shell structures [number‐average particle diameter (D_n) = 35–40 nm] were controlled by the variation of the feed amounts of the monomers and surfactant, or emulsion system. The size distributions were relatively narrow (weight‐average particle diameter/D_n ≈ 1.05). These particles had DC groups on their surface. Subsequently, poly(methyl methacrylate) brush encapsulated SiO₂ particles were synthesized by the grafting from a photoinduced atom transfer radical polymerization approach of methyl methacrylate initiated by SiO₂‐crosslinked PS particles as a macroinitiator. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO₂) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO₂ was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO₂ and modified SiO₂ were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO₂ and modified SiO₂ on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO₂ and modified SiO₂ was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO₂‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature (T_g) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry     

Interface of polyimide–silica grafted with different silane coupling agents: Molecular dynamic simulation

In this article, the effects of different silane coupling agents: 3‐glycidyloxypropyltrimethoxysilane (GOTMS), 3‐aminopropyltriethoxysilane (APTES), and 3‐methacryloxypropyltrimethoxysilane (MPTS), on the interface between polyimide (PI) and silica (SiO₂), were investigated using molecular dynamic simulation. The results indicate that binding energy between PI molecules and SiO₂ surface mainly comes from van der Waals interaction. Proper silane coupling agents generate a thin membrane on the surface of SiO₂, which improves the thickness of the transition layer between PI molecules and SiO₂ surface. And density of the transition layer was enhanced by APTES significantly. In addition, amino group (? NH₂) improves the electrostatic interaction between PI molecules and SiO₂ surface rather than epoxy group (? CH? CH₂? O) and methacrylic oxide group (? O? CO? C(CH₃)?CH₂). As a result, APTES enhances the binding energy effectively. However, excessive silane coupling agent increases the distance between PI matrices and SiO₂, which deteriorates performance of the interface. In addition, GOTMS and MPTS generate a thick and dense membrane on SiO₂ surface, which induces the loose transition layer and poor binding energy. Overlap parameter between PI molecules and SiO₂ surface grafted with silane coupling agent can be employed to evaluate the transition layer successfully. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45725.     

Synthesis and characterization of PMMA/SiO2 organic–inorganic hybrid materials via RAFT‐mediated miniemulsion polymerization

In this article, we first carried out the surface modification of SiO₂ using silane coupling agent KH570, and then prepared PMMA/SiO₂ organic–inorganic hybrid materials by conventional free radical polymerization and RAFT polymerization in miniemulsion, respectively. The kinetics comparisons of these two polymerizations were studied. PMMA/SiO₂ hybrid materials were characterized by gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. Experimental results indicated that the polymerization behavior of MMA in miniemulsion showed controlled/living radical polymerization characteristics under the control of RAFT agent. Incorporation of RAFT agent and SiO₂ nanoparticles improved the thermal properties of polymers, the thermal stability of polymers increased with increasing content of SiO₂ nanoparticles. The structures and morphologies of SiO₂, modified SiO₂, and PMMA/SiO₂ hybrid materials were characterized by FT‐IR and TEM. TEM results showed that the addition of modified SiO₂ nanoparticles to miniemulsion polymerization system obtained different morphology latex particles. Most of modified SiO₂ nanoparticles were wrapped by polymer matrix after polymerization. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Synthesis of hybrid TiO2 nanoparticles with well-defined poly(methyl methacrylate) and poly(tert-butyldimethylsilyl methacrylate) via the RAFT process

Surface of titania nanoparticles (TiO₂) was modified by a coupling agent as 3-(trimethoxysilyl)propyl methacrylate (MPS) to form TiO₂-MPS polymerizable particles. Methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (MASi) were radically polymerized through the immobilized vinyl bond on the surface in the presence of the reversible addition-fragmentation chain transfer (RAFT) agent 2-cyanoprop-2-yl dithiobenzoate using 2,2′-azobisisobutylnitrile (AIBN) as an initiator. FTIR spectroscopy confirmed the presence of the coupling molecule and the methacrylate groups on the surface. Thermogravimetric analysis and elemental analysis revealed a surface coverage of the coupling molecule of 2.0 wt%. TGA measurements showed that grafted PMMA and PMASi were accounted for 10% and 4.8% of the particle mass, respectively. ¹H NMR and SEC were used to verify the livingness of the polymerization. Transmission electron microscopy (TEM) was used to study the morphology of the particles before and after the surface grafting.     

Synthesis and characterization of PMMA/SiO2 nanocomposites by in situ suspension polymerization

Poly(methyl methacrylate) (PMMA)/SiO₂ nanocomposites were prepared by in situ suspension polymerization. Two types of modified methods were used to modify nano‐SiO₂: one was modification by γ‐methacyloxypropyl trimethoxy silane (KH570) and lauryl alcohol (12COH) while the other was grafting PMMA onto the surface of KH570 treated SiO₂. Transmission electron microscopy (TEM) and Fourier transformed infrared (FTIR) were used to characterize the structures of the nanocomposites. The influence of synthetic conditions, for instance, surface modification, initial SiO₂ contents and reaction temperature, on the microsphere's size and molecular weight of the extracted PMMA were studied by gel permeation chromatograph (GPC) and optical microscopy (OM) in details. Thermal property of the nanocomposites was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that the presence and content of SiO₂ have a vital effect on the shape and size of the nanocomposite microspheres, as well as molecular weight of the extracted PMMA. Grafting polymer to the surface of SiO₂ is an effective way for the purpose of effective in situ suspension polymerization. Compared to pure PMMA, the thermal properties of the nanocomposites were improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of polymer–inorganic hybrid nanoparticles via radical polymerization initiated by surface‐immobilized photoiniferter

Polymer–inorganic hybrid nanoparticles were prepared through radical photo‐polymerization of methyl methacrylate initiated by N,N‐diethyldithiocarbamyl surface functionalized silica nanoparticles under UV irradiation at ambient temperature. IR analysis and UV spectroscopy confirmed the occurrence of Et₂NCS₂—end groups on the resulting poly(methyl methacrylate), and the morphology of these hybrid nanoparticles was observed directly by means of tapping mode atomic force microscopy (AFM). Copyright © 2003 Society of Chemical Industry     

Study on structure and properties of SSBR/SiO2 co‐coagulated rubber and SSBR filled with nanosilica composites

The morphological structure, glass transition, mechanical properties, and dynamic mechanical properties of star‐shaped solution‐polymerized styrene‐butadiene rubber (SSBR) synthesized by a multifunctional organic lithium initiator and SiO₂‐SSBR composite (N‐SSBR) prepared through adding a small amount of nanosilica modified by silane coupling agent to star‐shaped SSBR synthetic solution and co‐coagulating, and their nanocomposites filled with 20 phr nanosilica were investigated, respectively. The results showed that the silica particles were well dispersed with nanosize in N‐SSBR, which glass‐transition temperature (T_g) was 2°C higher than SSBR. N‐SSBR/SiO₂ nanocomposite exhibited lower Payne effect and internal friction loss, higher mechanical properties, and its T_g was 2°C higher than SSBR/SiO₂ nanocomposite. N‐SSBR might promote the dispersion of nanosilica powder in matrix and could be applied to green tire tread materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nano‐SiO2/PMMA‐PU composite particles with core‐shell structure via emulsion polymerization and their application in epoxy resin

A novel method of nano‐SiO₂/poly(methyl methacrylate)(PMMA)‐polyurethane(PU) composite particles modifying epoxy resin is reported. The composite particles with the obvious core‐shell structure were prepared by emulsion polymerization of PMMA and PU prepolymer on the surface of nano‐SiO₂. The diameter of the composite particles was 50–100 nm with dark core SiO₂ (30–60 nm) and light shell polymer of PMMA and PU (20–30 nm); moreover, PU was well distributed in PMMA with about 10 nm diameter. After nano‐SiO₂ was encapsulated by PMMA and PU, the Si content on the surface decreased rapidly to 2.08% and the N content introduced by PU was about 1.27%. The ratio of polymer to original nano‐SiO₂ (f_p), the grafting ratio of polymer to original nano‐SiO₂ (f_r) and the efficiency grafting ratio of polymer (f_e) were, respectively, about 116.7%, 104.4%, and 89.5%. The as‐prepared composite particles were an effective toughness agent to modify epoxy resin, and the impact strength of the modified epoxy resin increased to 46.64 kJ m^?2 from 19.12 kJ m^?2 of the neat epoxy resin. This research may enrich the field of inorganic nanoparticles with important advances toward the modification for polymer composite materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41919.     

Preparation of monodispersed and lipophilic attapulgite and polystyrene nanorods via surface‐initiated atom transfer radical polymerization

A new kind of initiator, 3‐(2‐bromo‐2‐methylacryloxy)propyltriethysiliane (MPTS‐Br), was prepared with a simply hydrobrominated commercial silane coupling agent (3‐methacryloxy‐proplytriethysilane, MPTS). It has been one‐step self‐assemble onto the surface of attapulgite (ATP) nanorods in the dispersion system, and by using this initiator‐modified nanorod (MPTS‐Br‐modified ATP nanoparticles, ATP‐MPTS‐Br) as macroinitiator for atom transfer radical polymerization (ATRP). Structurally well‐defined homopolymer polystyrene (PS) and block polymer poly(styrene‐b‐methyl methacrylate) (PS‐b‐PMMA) chains were then grown from the needle‐shaped nanorods surface to yield monodispersed nanorods composed of ATP core and thick‐coated polymer shell (ATP and PS). The graft polymerization parameters exhibited the characteristics of a controlled/”living” polymerization. The PS‐grafted ATP nanorods could be dispersed well in organic solvent with nanoscale. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of PMMA grafted calcium carbonate whiskers and its reinforcement effect in PVC

In this study, calcium carbonate (CaCO₃) whiskers were grafted with poly(methyl methacrylate) (PMMA) by in situ emulsion polymerization using γ‐methacryloxy propyl trimethoxyl silane (γ‐MPS) as a coupling agent, and the properties of resultant whisker were determined using Fourier transform infrared (FTIR) spectroscopy, energy dispersive spectroscopy (EDS), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The results show that PMMA has been successfully grafted onto the surface of CaCO₃ whiskers and the maximum grafting degree (Gd) is 3.75%. The scanning electron microscopy (SEM) micrographs of the tensile‐fractured surfaces show that modified CaCO₃ whiskers have strong interfacial adhesion to the poly(vinyl chloride) (PVC) matrix. The tensile strength increases from 44.0 MPa for PVC composite with unmodified whisker to 49.5 MPa for that with grafted whisker. The dynamic mechanical analysis (DMA) and TGA results indicate that the composites reinforced by modified CaCO₃ whiskers have much higher modulus, glass transition temperature, and better thermal stability than their counterparts reinforced by unmodified CaCO₃ whiskers. POLYM. COMPOS., 38:2753–2761, 2017. © 2015 Society of Plastics Engineers     

Fabrication and characterization of in situ synthesized nano‐CaCo3‐reinforced polypropylene composite materials

To improve the impact toughness of polypropylene (PP), nano‐CaCO₃ was prepared by an in situ synthesis. The surface of the nano‐CaCO₃ was modified by KH‐550 silane coupling agent and NDZ‐401 titanium acid ester coupling agent. Nano‐CaCO₃/PP composite materials were fabricated through a melt‐blending method and characterized, and their mechanical properties were analyzed. The impact toughness and the tensile strength of the PP were improved significantly by the incorporation of nano‐CaCO₃. When the weight fraction of nano‐CaCO₃ was 2%, the maximum impact toughness and tensile strength of the PP nanocomposites were 293% and 259%, respectively, of the values for neat PP. Observation of the impact fracture surface of the nanocomposites indicated that the dispersion of nano‐CaCO₃ modified by NDZ‐401 coupling agent was more homogeneous than that of nano‐CaCO₃ modified by the KH‐550 silane coupling agent. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers