Morphology and thermal degradation studies of melt‐mixed PLA/PHBV biodegradable polymer blend nanocomposites with TiO2 as filler

The morphology and thermal stability of melt‐mixed poly(lactic acid) (PLA)/poly(hydroxybutyrate‐co‐valerate) (PHBV) blends and nanocomposites with small amounts of TiO₂ nanoparticles were investigated. PLA/PHBV at 50/50 w/w formed a co‐continuous structure, and most of the TiO₂ nanoparticles were well dispersed in the PLA phase and on the interface between PLA and PHBV, with a small number of large agglomerates in the PHBV phase. Thermogravimetric analysis (TGA) and TGA–Fourier‐transform infrared spectroscopy was used to study the thermal stability and degradation behavior of the two polymers, their blends, and nanocomposites. The thermal stability of PHBV was improved through blending with PLA, whereas that of the PLA was reduced through blending with PHBV, and the presence of TiO₂ nanoparticles seemingly improved the thermal stability of both polymers in the blend. However, the degradation kinetics results revealed that the nanoparticles could catalyze the degradation process and/or retard the volatilization of the degradation products, depending on their localization and their interaction with the polymer in question. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42138.     

In Situ synthesis of inorganic filler‐filled polyethylene using polyethersulfone‐supported TiCl4 catalyst system

In situ ethylene polymerizations with inorganic fillers were performed using catalyst based on titanium tetrachloride supported on polyethersulfone. The inorganic fillers used were MgO, TiO₂, and CaCO₃, which were pretreated with cocatalyst (methylaluminoxine) for better dispersion onto the polymer matrix. The formation of polyethylene (PE) within the whole matrix was confirmed by Fourier transform infrared studies. The wide‐angle X‐ray diffraction profile of the synthesized PEs indicated the presence of crystalline region. It was found that the nature of inorganic filler did not have any remarkable effect on the melting characteristics of the polymer, but the degree of crystallinity of PE was found to be higher for TiO₂‐filled PE. The amount of filler incorporated into the matrix was also evaluated through thermogravimetric analysis, where TiO₂‐filled PE showed ～ 49% of filler material, which was also reflected in the higher productivity obtained by this system. The morphology of the filler‐filled PEs was different, whereas the elemental dispersion was found to be uniform on the surface as elucidated through energy‐dispersive X‐ray spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biodegradable poly(L‐lactic acid)/TiO2 nanocomposites: Thermal properties and degradation

Poly(L ‐lactic acid)‐titanium dioxide nanocomposites (with various loadings of TiO₂: 0.5, 1, 2, 5, and 10 wt %) were produced by solution casting method. The influence of TiO₂ on thermal properties and crystallinity of PLA was investigated by DSC and FTIR spectroscopy. The TiO₂ nano filler has no significant influence on the characteristic temperatures (T_g, T_c, and T_m), but has high impact on the crystallinity of these systems. The degree of crystallinity X_c significantly increases for PLA nanocomposites loaded with up to 5 wt % of TiO₂, while for 10 wt % load of TiO₂ it drops below X_c of the pure resin. The degradation of the prepared composites was evaluated hydrolytically in 1N NaOH, enzymatically in α‐amylase solutions, and under UV irradiation. The catalytic effect of TiO₂ nano particles on the degradation processes under UV light exposure (λ = 365 nm) and hydrolytic degradation was confirmed with the increase of the filler content. The opposite effect was identified in enzymatic degradation experiments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Studying the degradation of polyhydroxybutyrate‐co‐valerate during processing with clay‐based nanofillers

Polyhydroxybutyrate‐co‐valerate (PHBV) is attracting interest as a new material for packaging applications and nanoparticulate layered silicates are being increasingly explored as a way to improve PHBV film properties. In this context, it is essential to understand how different types of nanofillers could influence polymer properties. PHBV was processed with three‐layered clay types using different mixing methods, and we examined the effect of processing time, clay type, and clay content on polymer molecular weight and composite morphology. PHBV molecular weight (M_w) decreased by 38% after extrusion processing and was further reduced in the presence of montmorillonite (MMT). However, when PHBV was processed with kaolinite as the additive, no further reduction in polymer molecular weight was observed. Molecular weight also decreased as the MMT clay content increased from 1 to 5 wt %. The results suggest that release of tightly bound water from clay surfaces at elevated temperature may be responsible for PHBV degradation during processing. Evidence also points to the possibility that the surface modifier present in organically modified MMT may catalyze PHBV degradation in some way. X‐ray diffraction studies indicated an intercalated morphology in the presence of modified montmorillonite but good dispersion was also achieved when unmodified kaolinite was blended with PHBV. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of cerium‐doped titanium dioxide/ultrahigh‐molecular‐weight polyethylene porous composites with excellent photocatalytic activity

Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO₂ nanoparticles (Ce–TiO₂/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO₂ nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO₂/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce⁴⁺ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO₂ attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO₂/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydrolysis of poly(hydroxybutyrate‐co‐hydroxyvalerate) nanoparticles

Poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) is a natural polyester known for its biocompatibility and biodegradability. The hydrolysis of PHBV nanoparticles (90–150 nm) and microparticles (33–58 µm) was investigated. Particles were formulated from preformed polymer(s) by miniemulsification/solvent evaporation technique to obtain nanoparticles or by emulsification/solvent evaporation technique to obtain microparticles. The morphology of the nanoparticles was studied by Field Emission Gun‐Scanning Electron Microscopy (FEG‐SEM). The kinetics of PHBV degradation was followed by gel permeation chromatography. After storage of PHBV nanoparticles for 25 days at 37 °C, the M_n and M_w of PHBV was reduced up to 85 and 80%, respectively. PHBV nanoparticles stored at 4 °C presented a much lower molecular weight reduction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydrophobic and tribological behaviors of a poly(p‐phenylene benzobisoxazole) fabric composite reinforced with nano‐TiO2

1H,1H,2H,2H‐Perfluorooctyl trichlorosilane (PFTS) was used to modify TiO₂ nanoparticles, and hydrophobic PFTS–TiO₂ nanoparticles were obtained by an ultrasonic reaction method. The PFTS–TiO₂ surface morphological and hydrophobic properties were analyzed with scanning electron microscopy (SEM), Fourier transform infrared spectrometry, and contact angle (CA) testing. Then, the poly(p‐phenylene benzobisoxazole) fabric–phenolic composite filled with PFTS–TiO₂ as a lubricant additive was fabricated by a dip‐coating process. The tribological properties of the composite were investigated, and the wear surface morphology was observed by SEM. The experimental results show that the water CA of the composite filled with PFTS–TiO₂ was 158°, and the composite containing 4 wt % PFTS–TiO₂ exhibited excellent antifriction and abrasion resistance. The hydrophobic surface of the composite showed excellent durable performance with a static water CA of 126.7° after abrasion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45077.     

Effect of titanium dioxide on the UV‐C ageing behavior of silicone rubber

The ultraviolet (UV)‐C ageing behavior of silicone rubber (SiR) incorporated with titanium dioxide nanoparticles (nano‐TiO₂) was studied under UV‐C radiation. The SiR incorporated with nano‐TiO₂ displayed excellent physical properties when exposed to UV‐C radiation. With the increase of the ageing time, the SiR with nano‐TiO₂ showed no significant change in crosslinking density and Shore A hardness. Moreover, compared with the SiR without nano‐TiO₂, the SiR incorporated with nano‐TiO₂ also exhibited high retention ratio in tensile properties, especially elongation at break. It was found that nano‐TiO₂ was a good ultraviolet light stabilizer during the UV ageing process of SiR and the optimum content of nano‐TiO₂ was 2 phr. The results of Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy showed the appearance of O? H and C?O and the decrease of the intensity of SiC₂O₂ in SiR samples during the process of UV‐C ageing. Based on these results, a possible UV ageing mechanism of SiR could be proposed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46099.     

Fabrication of functionally graded nano‐TiO2‐reinforced epoxy matrix composites

Functionally graded nano‐TiO₂ epoxy matrix composites were successfully fabricated using a centrifugal method. In the preparation of the composite, the aggregation of nano‐TiO₂ occurred during curing, which had a negative effect on the composite performance. To solve this problem, we introduced a silane coupling agent to modify the surface of the nano‐TiO₂, thereby improving the performance and mechanical properties simultaneously. The modified nano‐TiO₂ (s‐TiO₂) had better dispersion in the epoxy resin, making it possible to produce depth gradients of the mechanical properties of functionally graded materials (FGMs). The s‐TiO₂ was characterized with respect to functional groups, morphology, and chemical elements using transmission electron microscopy, X‐ray photoelectron spectroscopy, and Fourier‐transform infrared spectroscopy. The results show that a silane layer was successfully coated on the surface. Also, the gradients of the mechanical and permittivity properties of the FGM indicated that by modifying the surface of the nano‐filler, it is possible to fabricate nano‐filler‐reinforced epoxy matrix FGMs using a centrifugal method. POLYM. COMPOS., 35:557–563, 2014. © 2013 Society of Plastics Engineers     

Novel chitosan‐TiO2 nanohybrid: Preparation,characterization, antibacterial,and photocatalytic properties

In this report, chitosan (CS) encapsulated titanium dioxide (TiO₂) nanohybrid was prepared by chemical precipitation method. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD) confirmed the formation of nanohybrid. Transmission electron microscopy (TEM) analysis showed the immobilization of TiO₂ nanoparticles on the surface of CS. The nanohybrid was also characterized by thermogravimetric analysis (TGA) and zeta potential. The nanohybrid exhibited high photocatalytic activity as evident from the degradation of methylene blue (MB) dye. The result revealed substantial degradation of the MB dye (90%) under UV‐light illumination. The catalytic efficiency was unaltered even after five cycles of reuse. In addition, the nanohybrid exhibited a superior antibacterial activity of 100% within 24 h of treatment against Escherichia coli (E. coli) was measured by colony forming units (CFU). POLYM. COMPOS., 35:327–333, 2014. © 2013 Society of Plastics Engineers     

Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by ⁶⁰Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (T_o) and the temperature of maximum weight‐loss rate (T_p) of control and irradiated PHBV were in line with the heating rate (°C min^?1). T_o and T_P of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that ⁶⁰Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (T_m) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry     

Synthesis,characterization, and performance evaluation of PES/EDA‐functionalized TiO2 mixed matrix membranes for CO2/CH4 separation

Poor adhesion between hydrophobic polymers and hydrophilic inorganic fillers is a challenge that encumbers a high separation performance of mixed matrix membrane (MMM). In this study, Titanium(IV) oxide (TiO₂) nanoparticles were functionalized using ethylenediamine (EDA) before embedment in poly(ether sulfone) (PES) polymer matrix. MMMs were synthesized through dry phase inversion technique. Membranes morphology and nanoparticles dispersion was drastically enhanced posterior amine modification indicating an improved adhesion between the polymer and filler particles. Membranes thermal stability was likewise improved as higher degradation temperatures were perceived for PES/EDA–TiO₂ MMMs. Gas separation evaluation for pure carbon dioxide (CO₂) and methane (CH₄) gases revealed a remarkably enhanced separation performance upon amine‐grafting of TiO₂ as EDA‐TiO₂ MMMs exhibited a higher separation performance as compared to MMMs with pristine TiO₂. The highest ideal separation factor achieved was 41.52 with CO₂ permeability of 10.11 Barrer at an optimum loading of 5% wt of EDA‐TiO₂ which is threefold higher as compared to neat PES membrane and approximately twofold higher than MMMs with pristine TiO₂, respectively, at the same filler loading. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45346.     

Preparation of aerochitin‐TiO2 composite for efficient photocatalytic degradation of methylene blue

An aerochitin–titania (TiO₂) composite was successfully synthesized and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and N₂ adsorption isotherms. The photocatalytic activity of the composite was investigated on the degradation of the model organic pollutant, methylene blue (MB) dye, under UV irradiation. The aerochitin–TiO₂ composite showed excellent adsorptive and photocatalytic activity with a degradation degree of 98% for MB. The first‐order rate constants for the photodegradation MB by TiO₂ nanoparticles and aerochitin–TiO₂ composite were found to be (3.49 ± 0.04) × 10^?3 and (1.82 ± 0.02) × 10^?2 min^?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45908.     

Decomposition of gas‐phase aromatic hydrocarbons by applying an annular‐type reactor coated with sulfur‐doped photocatalyst under visible‐light irradiation

BACKGROUND: Unlike many water pollution applications, visible‐light‐driven photocatalysis of gas‐phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S‐doped visible‐light‐induced TiO₂ to treat gas‐phase aromatic hydrocarbons, using a continuous air‐flow annular‐type reactor. RESULTS: The prepared S‐enhanced TiO₂ powders, along with a commercially available TiO₂ powder (Degussa P‐25), were characterized using diffuse reflectance UV‐VIS‐NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p‐xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency. CONCLUSIONS: The S‐doped TiO₂ and undoped P25 TiO₂ powders exhibited different catalyst characteristics. The results demonstrate that an annular‐type reactor coated with visible‐light‐activated S‐doped TiO₂ can serve as an effective tool to treat gas‐phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry     

Preparation of novel nano/submicrofiber catalyst containing nano‐TiO2 particles

A novel Nano/submicrofiber catalyst was prepared via electrospinning technology from poly (vinyl pyrrolidone) (PVP) and nano‐TiO₂. First, nano‐TiO₂ particles were added into the mixture of ethanol and deionized water, the mass ratio of ethanol and deionized water was 1 : 1, the TiO₂ suspension was obtained after 1 h with ultrasonic treatment and centrifugal effect, Then PVP was added into the above‐mentioned suspension and the content of PVP in the sol was 28%. The TiO₂/PVP solution was electrospun with different voltage. The effects of the content of TiO₂ and electrospinning voltage on diameter of nano/submicrofiber were studied. The nano/submicrofiber catalyst was characterized by scanning electron microscopy, transmission electron microcopy, X‐ray diffraction, and Fourier transform infrared. The results show that the diameter of nano/submicrofiber increases with an increase of the content of nano‐TiO₂ and decreases with the increase of electrospinning voltage. The analytical result showed that the nano‐TiO₂ particles were well dispersed in the matrix of PVP, moreover, the crystal type of nano‐TiO₂ was a mixture of anatase and rutile and the diameter of nano‐TiO₂ particles in the nano/submicrofiber is in the range of 20–60 nm and the nano‐TiO₂ particle was monodisperse, and the nano‐TiO₂ particle and PVP molecule was connected by a hydrogen bonding. This nano/submicrofiber catalyst has a high efficiency on degradation on CH₂O. 56.8 percent of CH₂O was degraded under ultraviolet radiation in 80 min when the content of nano‐TiO₂ is 20% in nano/submicrofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Direct grafting poly(methyl methacrylate) from TiO2 nanoparticles via Cu2+‐amine redox‐initiated radical polymerization: An advantage of monocenter initiation

Cu²⁺ can oxidize amines to generate radicals to initiate radical polymerization of electron‐deficient monomers under mild conditions. Here, CuSO₄‐catalyzed redox‐initiated radical polymerizations of methyl methacrylate from amino‐functionalized TiO₂ nanoparticles (TiO₂‐NH₂ nanoparticles) was performed to prepare TiO₂ nanoparticles grafted with poly(methyl methacrylate) (TiO₂‐g‐PMMA hybrid nanoparticles) in dimethylsulfoxide or N,N‐dimethylformamide at 90°C. Infrared spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy confirmed the presence of the grafted PMMA and the grafting yield was about 50 wt%. Microscopy and particle‐size analysis indicated that TiO₂‐g‐PMMA nanoparticles had a good affinity to organic media. Because only aminyl radical (? NH?) on TiO₂ nanoparticles formed in Cu²⁺‐amine redox‐initiation step, there was no free PMMA chains formed during polymerization. Thus, our protocol provides a facile strategy to prepare inorganic/organic hybrid nanoparticles via one‐pot Cu²⁺‐amine redox‐initiated free radical polymerization. POLYM. ENG. SCI., 55:735–744, 2015. © 2014 Society of Plastics Engineers     

Preparation of poly(methyl methacrylate‐co‐maleic anhydride)/SiO2?TiO2 hybrid materials and their thermo‐ and photodegradation behaviors

The optically transparent poly(methyl methacrylate‐co‐maleic anhydride) P(MMA‐co‐MA)/SiO₂? TiO₂ hybrid materials were prepared using 3‐aminopropyl triethoxysilane as a coupling agent for organic and inorganic components. Real‐time FTIR was used to monitor the curing process of hybrid sol, indicating that imide group formation decreased with increasing titania content. scanning electron microscopy, atomic force microscopy, and differential scanning calorimetry results confirmed their homogeneous inorganic/organic network structures. TGA analysis showed that incorporated titania greatly prohibits the thermodegradation of hybrid films, especially at the content of 5.3 wt %, showing an increase of about 32.6°C at 5% loss temperature in air. The UV degradation behavior of P(MMA‐co‐MA) studied by quasi‐real‐time FTIR showed that TiO₂ incorporated in the hybrid network provides a photocatalytic effect rather than a UV‐shielding effect. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1714–1724, 2005     

Hybrid polyaniline–TiO2 nanocomposite Langmuir–Blodgett thin films: Self‐assembly and their characterization

Polyaniline (PANi)–titanium dioxide (TiO₂) nanocomposite materials were prepared by chemical polymerization of aniline doped with TiO₂ nanoparticles. Surface pressure–area (π‐A) isotherms of these nanocomposites show phase transformations in the monolayer during compression process. Multiple isotherms indicate that the monolayer of the nanocomposite material can retain its configuration during compression‐expansion cycles. Langmuir–Blodgett thin films of PANi–TiO₂ nanocomposite were deposited on the quartz and indium tin oxide coated conducting glass substrates. Fourier transfer infrared spectroscopy and UV–visible spectroscopy study indicates the presence of TiO₂ in PANi, whereas X‐ray Diffraction study confirmed the anatase phase of TiO₂ and particle size (～nm) of PANi–TiO₂. The morphology of Langmuir–Blodgett films of these nanocomposites was also characterized by atomic force microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41386.     

Preparation and characterization of electrospun polyurethane/inorganic‐particles nanofibers

To develop a novel functional fibrous scaffold, a blend‐electrospinning technique was applied to transfer polyurethane/inorganic‐particles solutions into nanofibers, in which titanium dioxide, copper, or/and silver nanoparticles were used. The resultant nanofibers were subsequently characterized by means of scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and tensile mechanical test. Furthermore, the structural change and the thermal properties of the electrospun fabrics were examined by X‐ray diffraction and differential scanning calorimetry, respectively. Antibacterial performance of the resulting nanofibrous mats on Escherichia coli and Staphylococcus aureus was also measured. Experimental results have shown that when the ratio of polyurethane solution and titanium dioxide sol was in 3.5:1, 89.55% of the Escherichia coli and 82.35% of the Staphylococcus aureus bacteria were killed under a UV‐light activation. However, the introduction of silver or/and cuprum nanoparticles into the polyurethane/TiO₂ (in the ratio of 3.5:1) nanofibers led to a significant improvement in their antibacterial ability without any photocatalysis.POLYM. COMPOS., 33:2045–2057, 2012. © 2012 Society of Plastics Engineers     

Biobased blends of poly(propylene carbonate) and poly(hydroxybutyrate‐co‐hydroxyvalerate): Fabrication and characterization

Poly(propylene carbonate) (PPC), a CO₂‐based bioplastic and poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) were melt blended followed by injection molding. Fourier transform infrared spectroscopy detected an interaction between the macromolecules from the reduction in the OH peak and a shift in the C?O peak. The onset degradation temperature of the polymer blends was improved by 5% and 19% in comparison to PHBV and PPC, respectively. Blending PPC with PHBV reduced the melting and crystallization temperatures and crystallinity of the latter as observed through differential scanning calorimetry. The amorphous nature of PPC affected the thermal properties of PHBV by hindering the spherulitic growth and diluting the crystalline region. Scanning electron micrographs presented a uniform dispersion and morphology of the blends, which lead to balanced mechanical properties. Incorporating PHBV, a stiff semi‐crystalline polymer improved the dimensional stability of PPC by restricting the motion of its polymer chains. © 2016 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44420.