Studies of polylactide/zinc oxide nanocomposites: influence of surface treatment on zinc oxide antibacterial activities in textile nanocomposites

Polylactide (PLA)/zinc oxide (ZnO) nanocomposite filaments were produced with a melt‐spinning process, with the aim of obtaining antibacterial textiles. ZnO, an inorganic antibacterial nanofiller, is used to impart antibacterial properties to PLA. These nanoparticles suit the melt‐spinning process because of their high thermal stability and low granulometry. Generally, metallic oxides (e.g., ZnO) are used to recycle PLA via catalyzed unzipping depolymerization. In this study, we used different ways to finely disperse ZnO in PLA and produce filaments with a minimum degradation of the thermal and mechanical properties. Optimized antibacterial properties were obtained with a fabric containing ZnO with specific surface treatments. The reasons for this better antibacterial activity, related to the study of the antibacterial mechanism of ZnO, were investigated with different characterization techniques [X‐ray, electron probe microanalysis, inductively coupled plasma mass spectrometry, and electron paramagnetic resonance (EPR)]. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41776.     

Structural,electrical, thermal,and gas sensing properties of new conductive blend nanocomposites based on polypyrrole/phenothiazine/silver‐doped zinc oxide

The main aim of this study is to investigate the effect of silver‐doped zinc oxide (Ag‐ZnO) loading on the structural, morphological, thermal and electrical properties, and gas sensing behavior of polypyrrole (PPy)/phenothiazine (PTZ)‐blend nanocomposites. The composites are characterized by FTIR, XRD, SEM, TEM, DSC, TGA, and impedance studies. FTIR spectra exhibit the presence of Ag‐ZnO in the PPy/PTZ blend. XRD analysis shows that the semicrystalline behavior of the polymer blend is greatly enhanced by the addition of Ag‐doped ZnO particles. Uniform dispersion of nanoparticles in the polymer is obtained from SEM analysis. The TEM images confirm the presence of spherically shaped nanoparticles in PPy/PTZ blend with a size of 10–25 nm. The DSC measurement indicates that the glass transition temperature of PPy/PTZ blend was significantly improved in the presence of Ag‐doped ZnO nanoparticles. The thermal decomposition temperature of nanocomposite obtained from TGA shows an increase with increase in the content of Ag‐ZnO particles. The incorporation of Ag‐doped ZnO nanoparticles to PPy/PTZ blend exhibit increase in the AC conductivity and dielectric properties of the nanocomposite, due to the pilling of charges at the extended interface of the composite system. The DC conductivity of the nanocomposite increases with the loading of nanoparticles. The ammonia gas sensing performance of PPy/PTZ/Ag‐ZnO nanocomposite is analyzed, and the result shows that the fabricated blend composite can be used as a promising candidate for the easy access of gas molecules. J. VINYL ADDIT. TECHNOL., 26:187–195, 2020. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.     

Influence of zinc oxide on thermoplastic elastomer‐based composites: Synthesis,processing, structural,and thermal characterization

It was aimed to investigate how thermal conductivity and stability properties of synthesized thermoplastic elastomers were influenced by zinc oxide (ZnO) additives which differed in size and surface treatment. ZnO particles were prepared by the homogeneous precipitation method by mixing aqueous solutions of hexamethylenetetramine (HMT) and zinc nitrate. The obtained particles were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Poly(vinyl pyrrolidone) (PVP) was used as a modifier to reduce aggregation among the ZnO particles. The composites, prepared by melt compounding method, were characterized in terms of their morphology and thermal properties. Uniformly distributed surface treated particles caused an enhancement in thermal conductivity properties. At 10 wt% ZnO concentration the thermal conductivity of composite reached 1.7 W/mK compared with 0.3 W/mK for the neat polymer. At the same filler loading, ZnO nanoparticles exhibited a greater effect on thermal conductivity compared with submicron sized particles. It was found that the coefficient of thermal expansion of composites decreased at low temperature (55°C) with increasing ZnO content. Thermal gravimetric analysis (TGA) showed that the neat polymer and the composites were resistant up to 340°C without significant mass loss. POLYM. COMPOS., 37:2369–2376, 2016. © 2015 Society of Plastics Engineers     

Barrier,rheological, and antimicrobial properties of sustainable nanocomposites based on gellan gum/polyacrylamide/zinc oxide

In this study, we used a solution casting method to prepare gellan gum (G)-based ternary nanocomposite films containing polyacrylamide (P) and zinc oxide (ZnO) nanoparticles. All composites were prepared using the chemical cross-linker N,N-methylenebisacrylamide. The nanocomposites were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and scanning electron microscopy. Attenuated total reflectance FTIR revealed strong hydrogen bonding interactions among gellan gum, polyacrylamide, and ZnO, which enhanced the physiochemical, thermal, and mechanical properties of the GPZnO nanocomposites. The addition of ZnO nanoparticles increased the glass transition temperature (T_g: 181.8–196.3°C), thermal stability (T_5%: 87.8–96.5°C), and char yield (23.9–29.1%) of the GP composite films, as well as their the tensile strength (from 33.5 to 43.8 MPa) and ultraviolet (UV) blocking properties (~99.2% protection against UVB [280–320 nm]). ZnO significantly influenced the rheological properties of the GP composite. The prepared GP and GPZnO nanocomposites exhibited shear thinning behavior and their viscosities decreased when there is an increase in shear rate. Storage and loss modulus increased with frequency with the addition of ZnO nanoparticles. The GPZnO films exhibited reduced hydrophilicity, moisture content, and water barrier properties compared with the GP film. The GPZnO nanocomposites exhibited effective antimicrobial activity against six different pathogens. The prepared GPZnO films could be useful in biodegradable packaging applications.     

Reinforcement of polymethyl methacrylate with silane-treated zinc oxide nanoparticles: fire retardancy,electrical and mechanical properties

Polymethyl methacrylate (PMMA)/zinc oxide (ZnO) composites were prepared using melt mixing process. A nano ZnO-treated with aminopropyl triethoxysilane (APTS) was used as reinforcing particles. PMMA composites were obtained with different ZnO loadings of 0, 0.5, 1 and 2 parts by weight. This research was focused on determination of the influence of different loadings of silane-treated ZnO particles on the morphology, electrical, mechanical and flammable properties of the PMMA composites. Addition of ZnO to the PMMA composite was observed to enhance the thermal properties and char formation. The results from cone calorimeter showed 21% reduction in the peak heat release rate for the composite loaded with 1.5 wt% of ZnO as compared to that of neat PMMA. The surface resistivity, volume resistivity and EMI shielding properties of the composites as a function of ZnO loading were estimated. The results showed that the surface and volume resistivity of the composites reinforced with ZnO particles decreased and the EMI shielding increased almost linearly with increasing ZnO volume content. However, the tensile strength of the composites showed a slight decrease with increase in ZnO content. The SEM micrographs and AFM images showed dispersion of ZnO particles in the PMMA matrix. The nanoparticles were distributed evenly on the surface. Nevertheless the pockets of agglomerates could be seen at higher ZnO loading level.     

Effects of zinc oxide nanoparticles on the physical properties of polyacrylonitrile

Polyacrylonitrile (PAN)/zinc oxide (ZnO) nanocomposites were prepared by solution mixing in dimethylacetamide, followed by film casting, and their physical properties were investigated. The heating scan of differential scanning calorimetry displayed only a single crystallization peak (T_c) without a melting peak, regardless of the presence of ZnO. The incorporation of ZnO nanoparticles decreased T_c by 13°C, and increased the heat of crystallization by 18%. Further, it greatly improved the thermal stability of PAN, even at the ZnO content as low as 0.1 wt %. The nanocomposites showed the UV transmittance peak at 365 nm, whose intensity was increased as ZnO content was increased. The presence of ZnO did not produce new peak nor shift the peaks with respect to PAN in wide angle X‐ray diffraction pattern. Introduction of a small amount of ZnO nanoparticles did not have notable effect on the tensile properties. However, 5 wt % loading of the nanoparticles increased the tensile modulus of PAN by 14.5% and decreased elongation at break dramatically. PAN nanocomposites with 5 wt % ZnO did not show any plateau region in stress–strain curve. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1854–1858, 2006     

The effect of alginate on the mechanical,thermal, and rheological properties of nano calcium carbonate‐filled polylactic acid composites

Traditional plasticizers to modify polylactic acid (PLA) usually leads to limited biodegradation, due to its inherent non‐biodegradability of additives. In this work, we report a melt blending method to modify PLA using the alginic acid and two different alginates combined with nano CaCO₃, a fully sustainable and biodegradable component. And, the mechanical, thermal, and rheological properties of the composites are investigated. We demonstrated that the filled samples show a lower tensile strength and higher impact strength which means a toughening effect occurs. Dynamic mechanical analysis experiments showed that the calcium alginate‐filled samples show higher performances than other filled samples not only in static mechanical but also dynamic mechanical properties. The fracture morphology of the samples shows that a better interfacial reaction has been constituted for gel calcium alginate between CaCO₃ and PLA. Nevertheless, the thermogravimetric analysis results indicate that a lower thermal stability has been achieved in alginate filled samples. Chemorheological study indicated the alginate‐filled samples also show a lower modulus and viscosity than neat PLA. It was found that the complex viscosity decrease with the addition of alginates, in comparison with PLA/CaCO₃ composites, and the samples filled with calcium alginate show a higher viscosity than those of sodium alginate and alginic acid. The alginate derivatives showed interesting potential as new green plastic additives attributed to origin from the biodegradable natural resources with a polymeric matrix. POLYM. ENG. SCI., 59:1882–1888, 2019. © 2019 Society of Plastics Engineers     

Hydrolysis and thermal degradation of poly(L‐lactide) in the presence of talc and modified talc

Talc and talc modified with trimethoxy(octadecyl)silane (O‐talc) were melt compounded with poly (L ‐lactide) (PLA). The crystallization behavior, tensile properties, and impact strength of the PLA composites were examined before and after the incorporation of talc and O‐talc. The molecular weight of PLA in the PLA composites was measured as a function of the hydrolysis time and temperature. The effect of talc and O‐talc on the thermal stability of PLA was examined and quantified by the activation energy of thermal degradation and the integral procedural decomposition temperature value determined from the corresponding thermo‐gravimetric analysis weight loss profiles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

New multifunctional poly(lactide acid) composites: Mechanical,antibacterial, and degradation properties

The aim of this work was to study the effect of the innovative combination of microcrystalline cellulose (MCC) and silver nanoparticles (Ag) on the poly (lactide acid) (PLA) composite properties, to modulate the PLA mechanical response and induce an antibacterial effect. The preparation and characterization of PLA‐based composites with MCC and Ag nanoparticles by twin‐screw extrusion followed by injection molding is reported. A film procedure was also performed to obtain PLA and PLA composite films with a thickness ranged between 20 and 60 μm. The analysis of disintegrability in composting conditions by means of visual, morphological, thermal, and chemical investigations was done to gain insights into the post‐use degradation processes. Tensile test demonstrated the MCC reinforcing effect, while a bactericidal activity of silver‐based composites against a Gram‐negative bacteria (Escherichia coli) and a Gram‐positive bacteria (Staphylococcus aureus) was detected at any time points and temperatures analyzed. Moreover, the disintegrability in composting showed that MCC is able to promote the degradation process. The combination of MCC and Ag nanoparticles in PLA polymer matrix offers promising perspectives to realize multifunctional ternary composites with good mechanical response and antibacterial effect, maintaining the optical transparency and the disintegrability, hence suitable for packaging applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Poly(lactic acid)/low‐density polyethylene blends and its nanocomposites based on sepiolite

Poly(lactic acid) (PLA) nanocomposite ternary blends based on unmodified sepiolite were prepared by melt blending using a corotating twin‐screw extruder. Two grafted polymers were used as compatibilizer agents, in an effort to increase the PLA tensile toughness. The influence of incorporating a low‐cost commodity low‐density polyethylene, as dispersed phase to the composites on thermal degradation, and rheological and tensile properties was studied. The morphology of the blends and composites was determined through transmission and scanning electron microscopy techniques. Results showed that the compatibilized blends prepared without clay have higher thermal degradation susceptibility and tensile toughness than those prepared with sepiolite and significant changes in complex viscosity and melt elasticity values were observed between them. The nanocomposite blends exhibited similar thermal degradation, lower tensile strength, and Young's modulus values and increased elongation at break and tensile toughness, complex viscosity, and storage modulus compared with those of the nanocomposite of PLA. These results are related to the clay dispersion, to the type of morphology of the different blends, to the localization of the sepiolite in the different phases, the thermomechanical degradation of the PLA matrix phase during melt blending and the grafting degree of the compatibilizers used. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

In situ intercalation green polymerization,characterization, and kinetics of poly(lactic acid)/zinc oxide pillared saponite nanocomposites

Poly(lactic acid) (PLA)/Zinc oxide (ZnO) pillared saponite nanocomposites were prepared with ZnO pillared saponite as the green catalyst and lactic acid as monomer through in situ intercalation polymerization method. The optimum polymerization parameters were as follows the addition content of ZnO pillared saponite was 1% (wt) and the reaction was running at 180°C for 7 h. The Fourier transform infrared and ¹H NMR results showed that the polymerization sample was PLA; Gel permeation chromatography result showed the PLA had a narrow molecular weight distribution, which arranged from 3,000 to 5,000 and the polydispersity index of PLA was 1.2. Differential scanning calorimetry showed ZnO pillared saponite improved the crystallinity of PLA. Thermogravimetric analysis showed the thermal stability of PLA‐based nanocomposites were improved by ZnO pillared saponite. It was shown that in situ intercalative polymerization kinetics model of PLA/ZnO pillared saponite nanocomposites accorded with third order, and the activation energy of polymerization reaction was 49.3 kJ/mol under the polymerization reaction conditions as follows: the vacuum degree was 0.085 MPa, the temperature was 130°C, and the reaction extent was 2.35∼47.69%, the content of ZnO pillared saponite catalyst was 1 wt%. POLYM. COMPOS., 35:1023–1030, 2014. © 2013 Society of Plastics Engineers     

The effects of modified zinc oxide nanoparticles on the mechanical/thermal properties of epoxy resin

Characterized by its strength, durability, and thermal properties, epoxy resin has been widely used as an adhesive, paint, and coating in many applications in the aerospace, civil and automotive industries. Despite this, the thermoset polymer resin has been known for its brittleness and low fracture resistance. This study focuses on the reinforcement of an epoxy resin system (diglycidyl ether of bisphenol A) with zinc oxide (ZnO) nanoparticles in their pristine form and a further modified form. The modification took place in two ways: coating with polydopamine (PDA) and covalently functionalizing them with (3-aminopropyl)triethoxysilane (APTES) and (3-glycidoxypropyl)trimethoxysilane (GPTMS). Therefore, four different types of nanoparticles were used: pristine ZnO, ZnO/PDA, ZnO/GPTMS, and ZnO/APTES aiming to improve the interfacial bonding between the polymeric matrix and the reinforcement. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, and scanning electron microscopy characterization and imaging techniques were used to prove that the ZnO nanoparticles were successfully modified prior to manufacturing the epoxy composites. While tensile testing showed that using pristine ZnO increases the composite's strength by 32.14%, the fracture toughness of the resin was improved by 9.40% when reinforced with ZnO functionalized with APTES. TGA showed that the addition of functionalized nanoparticles increases the material's degradation temperature by at most 7.31 ± 4.9°C using ZnO/APTES. Differential scanning calorimetry and dynamic mechanical analysis testing proved that the addition of any type of nanoparticles increases the resin's glass transition temperature by as much as 7.83°C (ZnO/APTES).     

Thermal,thermomechanical, and morphological characterization of poly(vinyl chloride) (PVC)/ZnO nanocomposites: PVC molecular weight effect

Poly(vinyl chloride) (PVC)‐based nanocomposites containing 2 wt% zinc oxide (ZnO) nanoparticles were prepared by solution casting and the effect of the PVC molecular weight (MW) on the morphology, thermal properties, and thermogravimetric behavior was studied. The addition of ZnO nanoparticles to PVCs of different MWs increased the glass transition temperature (T_g) of the resulting nanocomposites, the extent of which was dependent upon the MW of the PVC matrix. The nanocomposite samples exhibited broadened transition zones as compared with their unfilled PVC matrices. The extent of transition zone broadening was also controlled by the MW of the PVC matrix in the nanocomposites. In the absence of ZnO nanoparticles, the increase in MW of PVC had no effect on the breadth of the transition zone. The TGA results showed that the incorporation of ZnO nanoparticles into PVC matrices of different MWs accelerated the first stage weight loss via the nanoparticle catalytic effect through removal of HCL from the polymeric chains. The presence of ZnO nanoparticles lowered the second stage weight loss, and the char yield obtained for nanocomposites samples was significantly greater than that obtained for neat PVC samples. At low MWs, the presence of ZnO nanoparticles had no effect on the first stage of thermal degradation process. The presence of ZnO nanoparticles in the matrix in different nanocomposites was revealed by SEM observations, and the EDX analysis demonstrated a progressive improvement in the distribution and dispersion state of ZnO nanoparticles in the PVC‐based nanocomposites as the MW of PVC matrix gradually increased. J. VINYL ADDIT. TECHNOL., 25:E63–E71, 2019. © 2018 Society of Plastics Engineers     

Enhancing the durability of poly(lactic acid) composites by nucleated modification

Biodegradable poly(lactic acid) (PLA) composites were prepared using an innovative combination of wood fiber (WF) and 1,3,2,4‐bis(3,4‐dimethylobenzylideno)sorbitol (DMDBS). DMDBS acted as an effective nucleating agent, which improved the mechanical properties and slowed down the degradation of the WF/PLA composites. The enzymatic degradation of the composites was examined by immersing in proteinase K or cellulase buffer. The presence of DMDBS resulted in a 26.7% increase of the crystallinity compared to the WF/PLA composites. The increase in crystallinity enhanced the thermal stability and tensile strength of the WF/DMDBS/PLA composites by 8.5%. The durability of the WF/DMDBS/PLA composites after nucleated modification was enhanced after enzymolysis. After nucleated modification, the surface of the WF/PLA composites showed clear cracks due to degradation, while these appeared about 2 weeks later in the case of the WF/DMDBS/PLA composites. The results revealed that the introduction of cellulase degraded WF in the composites, which increased hydrolysis or enzymolysis sites. The combination of nucleated modification and enzyme buffer gave an expanded downstream application of WF/PLA composites in packaging and agricultural materials. © 2019 Society of Chemical Industry     

Preparation of highly emissive,thermally stable,UV‐cured polysilsesquioxane/ZnO nanoparticle composites

A high molecular weight polysilsesquioxane (LPMSQ)/ZnO nanocomposite was prepared by blending a methacryl‐substituted polysilsesquioxane and PMMA‐coated ZnO nanoparticle (NP) followed by UV‐curing process. These LPMSQ/ZnO nanocomposites gave high thermal and mechanical stabilities originated from the rigid ladder structured siloxane backbone of LPMSQ. The polysilsesquioxane and surface‐modified ZnO nanoparticles showed excellent compatibility between MMA groups in LPMSQ‐ and PMMA‐capped ZnO nanoparticles to give well‐dispersed LPMSQ/ZnO nanocomposites. Mechanically pliant and flexible free standing films were obtained, and the photo and optical properties of these hybrid nanocomposites were examined. The high photoluminescent properties were maintained even after severe thermal treatments exceeding 400°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42333.     

Melt rheology of poly(lactic acid): Consequences of blending chain architectures

The rheology of blends of linear and branched poly(lactic acid) (PLA) architectures is comprehensively investigated. Measurement of the melt rheological properties of PLA is complicated by degradation effects but the addition of 0.35 wt% tris(nonylphenyl) phosphite (TNPP) provides excellent stabilization over a range of temperatures. Master curves of dynamic viscosity constructed using time‐temperature superposition show significant dispersion for unstabilized samples; this behavior is accompanied by a loss of molecular weight. TNPP stabilized samples show excellent superposition throughout the entire frequency range and minimal loss in molecular weight. For the linear architecture, the Cox‐Merz rule is valid for a large range of shear rates and frequencies. The branched architecture deviates from the Cox‐Merz equality and blends show intermediate behavior. Both the zero shear viscosity and the elasticity (as measured by the recoverable shear compliance) Increase with increasing branched content. The viscosities of both the unstabilized samples and the TNPP stabilized samples roughly obey a log additivity mixing rule. The recoverable shear compliance is monotonic in blend composition and a mixing rule for this property is also presented. For the linear chain, the compliance is independent of temperature but this behavior is apparently lost for the branched and blended materials. Tensile and thermal properties of the blends are also measured and found to be roughly equal within the statistical error of the experiments. The results suggest that excellent control over rheological behavior of PLA is possible through blending chain architectures without compromising mechanical properties.     

Effect of modified ZnO nanoparticle on the properties of polylactide ultrafine fibers

Zinc oxide (ZnO) was modified with hexadecyltrimethoxysilane (HDTMS) to obtain hydrophobicity and used to reinforce polylactide (PLA), an environmentally friendly polymer. The PLA/HDTMS-modified ZnO (m-ZnO) nanocomposite prepared by adding m-ZnO to the PLA matrix was fabricated into ultrafine fiber using electrospinning. Neat PLA and PLA/ZnO were used for comparisons. Structural analysis of the nanoparticles proved that the ZnO was modified successfully, and that the modification affected dispersibility and hydrophobicity, as observed by morphological, visual, and water repellency tests. The morphological analysis of the electrospun ultrafine fabrics under suitable conditions confirmed that the nanoparticles were well incorporated, and the desired functional changes were observed. Measurement of water repellency and mechanical, thermal properties were used to analyze the effect of nanoparticle modification and composition on fabrics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47446.     

Effects of mixing technique and filler content on physical properties of bovine bone‐based CHA/PLA composites

This study presented influence of mixing technique as well as filler content on physical and thermal properties of bovine bone‐based carbonated hydroxyapatite (CHA)/poly(lactic acid) (PLA) composites. CHA/PLA composites at various contents of CHA were prepared by either melt‐mixing or solution‐mixing techniques. Thermal properties, morphologies, and mechanical properties of the CHA/PLA composites including molecular weight deterioration of PLA matrices were investigated. Average molecular weights of PLA in the composites prepared by both techniques decreased with increasing CHA content, whereas their molecular weight distributions (MWDs) increased. Nonetheless, average molecular weights of PLA in melt‐mixed composites were lower than those of solution‐mixed composites. With increasing CHA content, elongation at break, tensile strength, and impact strength of the composites were decreased, whereas the tensile moduli of the composites were increased. In comparison between two mixing techniques, the melt‐mixing distributed and dispersed CHA into PLA matrix more effectively than the solution‐mixing did. Therefore, tensile moduli, tensile strength, and impact strength of the melt mixed composites were higher than those of the solution‐mixed composites of the corresponding CHA content. Moreover, decomposition temperatures and % crystallinity of the melt‐mixed composites were higher than those of the solution‐mixed composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

On the interesting optical properties of highly transparent,thermally stable,spin‐coated polystyrene/zinc oxide nanocomposite films

In the present work, polystyrene/zinc oxide (PS/ZnO) nanocomposite films are prepared by simple mixing followed by film deposition, using spin‐coating technique. Although there are a few reports on the UV‐shielding properties of PS/ZnO nanocomposite films, these reports deal with rather thick films obtained by solution casting. Spin coating is a more advantageous technique where one can control the film thickness by suitably adjusting the viscosity of the solution and the spinning speed and get homogeneous films with thickness around a few hundreds of nanometers. These aspects provide the motivation for the present work where emphasis is given to investigating the optical properties of PS/ZnO nanocomposite films obtained by spin coating and analyzing the effects of each component of the composite (PS/ZnO) on the properties of the other. The nanocomposite films are found to be highly transparent throughout the visible region and the thermal stability is better compared with PS. The optical absorption of the composite films in the UV region is quite high, and this aspect highlights the prospects of applications of these films in UV shielding. The PS matrix brings about considerable surface modification of ZnO nanoparticles, resulting in the reduction of defect states within ZnO and facilitating sharp, near band edge photoluminescence emission. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Zinc oxide nanoparticles catalyze rapid hydrolysis of poly(lactic acid) at low temperatures

Poly(lactic acid) (PLA), a biobased, degradable polymer has been used recently in the field of oil and gas. These applications require rapid hydrolytic degradation of PLA especially at low temperatures. This work reports a simple and ready‐to‐scale up chemistry of using zinc oxide nanoparticles (ZnO NPs) to catalyze the hydrolytic degradation of PLA at the temperatures well below its glass transition temperature. Furthermore, for the first time, we have applied the nondestructive analytical method of ¹H T₂ NMR relaxometry to measure the apparent rate constants of PLA hydrolysis in solid, heterogeneous/composite systems that have multiple and complex reaction kinetics. We demonstrate that the activation energy for ZnO catalyzed PLA hydrolysis is about 38% lower than that of pure PLA hydrolysis. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40287.