Modifying biodegradable plastics with additives based on condensed tannin esters

Condensed tannins derived from Pinus radiata bark have been esterified and added to biodegradable plastics as extrusion compounded functional plastic additives. The presence of longer alkyl chain hexanoate esters promoted tannin miscibility in the commercial polyesters Bionolle? and Biopol? whereas short chain acetate esters tended to remain as discrete domains, acting as fillers in the processed plastics. In the aliphatic polyester Bionolle the presence of tannin esters at typical plastic additive loadings did not alter plastic mechanical properties whereas at 5% content in Biopol the tannin‐additives reduced both flexural and tensile properties. Similarly tannin esters do not alter the melt or glass transition temperatures of the polyesters, but tannin hexanoate at 5% can influence the crystallization temperatures. Artificially aging plastics realized the functionality these plant extracts can impart to plastics in acting to reduce ultraviolet (UV)‐induced plastic degradation. Results indicate the tannin‐additives likely provide a stabilising role through inhibiting UV penetration into the plastic, with color analysis suggesting the tannin moiety itself was sacrificial and preferentially degrading. The imparted UV stability was linked to the dissolution of tannin esters in the plastic with longer chain esters providing greater protection against UV degradation. Tannin esters showed potential as functional additives for biodegradable polymers enhancing the UV stability of the plastic. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41626.     

Nanoclay‐reinforced,polypropylene‐based wood–plastic composites

Wood plastic composites (WPCs) are a new class of materials which combine the characteristics of plastic and wood. In appearance, they are similar to wood, but the low stiffness of plastics makes the composite modulus significantly lower than that of solid wood. Increasing the wood content in the WPCs can improve stiffness, but the rate of water absorption also goes up. Here, nanoclay was compounded with wood and plastic using a twin screw extruder to form a three‐component composite to improve the stiffness of WPCs. To overcome the previously observed reduction in strength and increase in the rate of water absorption, different compounding procedures were used. It was found that pre‐compounding wood flour with polymer followed by incorporation of clay in a second step resulted in an increase in stiffness, retention in strength, and a reduction in the rate of water absorption. Thus, adding nanoclays is an alternative for increasing properties instead of adding extra wood flour to a concentration in excess of 55 wt% as this involves processing difficulties. POLYM. ENG. SCI., 50:2013–2020, 2010. © 2010 Society of Plastics Engineers     

Preparation of Novel Fluorinated Copolyimide/Amine‐Functionalized Sepia Eumelanin Nanocomposites with Enhanced Mechanical,Thermal, and UV‐Shielding Properties

Novel fluorinated copolyimide/amine‐modified sepia eumelanin (ASE) nanocomposites are successfully fabricated via covalent bonds. To achieve this, the polyimide (PI) is synthesized by random co‐polycondensation. The effects of ASE on the structure and properties of the PI are investigated. A multilinked network is formed with ASE acting junctions in the nanocomposites. The mechanical properties of the PI are significantly improved by the addition of ASE, and the optimal tensile strength and elongation at break are 79.7 MPa and 85.42%, respectively. UV–vis transmittance, methylene blue (MB) photodegradation, and recyclability measurements confirm that the PI/ASE nanocomposites are transparent to visible light at low ASE loadings and show outstanding UV‐shielding properties and lifetimes under intense UV irradiation owing to the synergistic absorption of UV light by the PI matrix and ASE. Furthermore, the PI/ASE nanocomposites have enhanced thermal properties with initial degradation temperatures above 500 °C. These properties endow the nanocomposites with great potential for UV‐shielding in the conditions with high temperature and intense ultraviolet light.     

Influence of a long‐side‐chain‐containing reactive diluent on the structure and mechanical properties of UV‐cured films

The dimethacrylate reactive diluent (HEMA‐DDSA), a long‐side‐chain‐containing reactive diluent, was prepared by reacting 2‐dodecen‐1‐ylsuccinic anhydride with two equivalents of hydroxyethyl methacrylate. Its structure was characterized by IR and ¹H NMR spectroscopy. This new diluent was added into the formulation of UV‐curable epoxy acrylate networks. Results show that the formulation with the addition of HEMA‐DDSA has massively reduced viscosity and shows several attractive properties of epoxy acrylate oligomers. The mechanical resistance of the films is dramatically enhanced with the incorporation of long alkyl groups derived from HEMA‐DDSA, the plastic deformation zone expands, thus decreasing the inner stress of the polymer structure. Moreover, the cured coatings have a higher glass transition temperature as the percentage of HEMA‐DDSA is increased up to 5 wt%. Due to the excellent integrated performance of the polymeric films, HEMA‐DDSA proved to be an effective reactive diluent, which is of potential interest for applications in high performance materials. © 2016 Society of Chemical Industry     

Molecular weight studies of the γ‐irradiation degradation of poly(methyl methacrylate) doped with poly(p‐sulfanilamide)

The protection of some poly(methyl methacrylate) (PMMA) samples against γ rays was investigated in the absence and presence of poly(p‐sulfanilamide). Pure PMMA (without additives) and PMMA–poly(p‐sulfanilamide) blend samples were irradiated with γ rays for different exposure doses (5, 15, 25, 35, 50, 75, and 100 kGy). The viscosity‐average molecular weights were determined and thin‐layer chromatography measurements were carried out after each irradiation dose. The maximum protection against γ rays was found when 1% poly(p‐sulfanilamide) was used. The radiation chemical yield for main scission (G_s) was calculated and had lower values in the case of 1% poly(p‐sulfanilamide). The energy absorption per scission was maximum for 1% poly(p‐sulfanilamide), and this confirmed the obtained G_s data. From thin‐layer chromatography studies, it was observed that both the retention factor (R_f) values and polydispersity of the PMMA samples increased with an increasing exposure dose. The effect of γ irradiation on PMMA films doped with 1% poly(p‐sulfanilamide) was investigated with UV spectroscopy after the extraction of the additives. A change in the intensity of the absorption bands with an increasing irradiation dose was recorded. It is suggested that PMMA films doped with this type of polymer can be used as dosimeters. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Curing and combustion properties of a PU‐coating system with UV‐reactive phosphazene

A UV‐curable polyurethane (PU)‐coating system containing phosphorus is formulated by the combination of photoinitiator, PU acrylate oligomer, and UV‐reactive phosphazene monomer. PU acrylate oligomer is prepared by the addition of 2‐hydroxyethylmethacrylate (HEMA) to NCO‐terminated PU prepolymer. UV‐reactive phosphazene monomer is derived from the HEMA substitution reaction to hexachlorocyclotriphosphazene (NPCl₂)₃. The curing reaction of this PU‐coating system is carried out by UV irradiation. The resultant UV‐cured PU‐coated films demonstrated better performance properties than those of original UV‐cured PU acrylate (UV‐PU) without UV‐reactive phosphazene monomer. Furthermore, their thermal properties are investigated by a thermogravimetric analyzer and a dynamic mechanical thermal analyzer, respectively. The combustion behaviors of these UV‐cured PU‐coated films are evaluated by the measurements of a limiting oxygen index and a cone calorimeter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1980–1991, 2002     

Studying the mechanisms of titanium dioxide as ultraviolet‐blocking additive for films and fabrics by an improved scheme

Titanium dioxide (TiO₂) has good ultraviolet (UV)‐blocking power and is very attractive in practical applications because of such advantages as nontoxicity, chemical stability at high temperature, and permanent stability under UV exposure, for example. Development of nanoscience and ‐technology provides new ways for better treatment for UV‐resistant films and fabrics using TiO₂. However, the exact mechanisms of TiO₂ as a UV‐blocking additive are still not very clear, and researchers hold different views on this issue. The aim of this investigation was to study systematically the mechanisms of TiO₂ as a UV‐blocking additive for films and fabrics. To achieve this goal, the conventional scheme describing light interactions with fabrics was revised based on more recent progress in optical theory, and special experiments and analytic methods were used in the investigation. Several effects attributed to the nanoscale additives were identified. Moreover, detailed analyses based on the results yielded a few important suggestions useful in developing or improving both inorganic UV‐blocking agents and the UV‐protective films and textiles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3201–3210, 2004     

Mechanical properties development of sodium alginate films with additives by UV‐radiation processing

To improve mechanical properties of polymer films; sodium alginate (SA) films was prepared with ethylene glycol (EG) and photocured. The formulation was prepared at various concentration with EG and photoinitiator (2%) in methanol. The mechanical properties were optimized in case of monomer (EG) concentration, soaking time, and radiation dose of intensities. The highest polymer loading (PL) was 7.1% and tensile strength (TS) of the film was 37.9 MPa were found for 3 min soaking in 5% EG containing formulation at 20th pass of UV radiation; the highest value (22%) of elongation at break (Eb) was obtained at 1 min soaking time at 15th passes of UV doses. The mechanical properties improvement of the films varied acrylic monomers; such as 2‐ethylhexylacrylate (EHA), 1,4‐butanediol diacrylate (BDDA), and trimethylpropane triacrylate (TMPTA) were used as additives (2%) in the optimized formulation. The highest PL (12.7%) and TS (42.2 MPa) of the films are at 5% EG, 2% TMPTA, and 2% photoinitiator in methanol at 3 min soaking time at 20th pass of UV radiation. The highest Eb (25%) was obtained using additives 2% EHA additives in 5% EG and 2% photoinitiator in methanol at 3 min soaking time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Exceptionally good,transparent and flexible FeS2/poly(vinyl pyrrolidone) and FeS2/poly(vinyl alcohol) nanocomposite thin films with excellent UV‐shielding properties

Composites of nanocrystalline iron disulfide (FeS₂) coated with poly(vinyl pyrrolidone) (PVP) or poly(vinyl alcohol) (PVA) have been successfully synthesized using a solvothermal process, in which PVP and PVA serve as soft templates. Transparent, flexible thin films of these nanocomposites were prepared from homogeneous solution using a solution‐casting approach. X‐ray diffraction and thermogravimetric analysis and energy‐dispersive X‐ray, Fourier transform infrared and UV‐visible absorption spectroscopic techniques were employed to study the structural and optical properties of these nanocomposite films. UV‐visible spectra in transmission mode reveal the UV‐shielding efficiency of these nanocomposite films and the films are found to be exceptionally good for UV‐shielding applications in the wavelength range 200 to 400 nm. The present work aims at developing transparent and flexible UV‐shielding materials and colour filters using cost‐effective and non‐toxic inorganic–polymer nanocomposites. © 2012 Society of Chemical Industry     

Ultra‐high‐molecular‐weight functional siloxane additives in polymers. Effects on processing and properties

Two new types of solid siloxane additives for plastics are described which give improved benefits compared to previous silicone additives. Ultra‐high‐molecular‐weight (UHMW) siloxanes are used in the new additives; traditional silicone plastic additives have used much lower molecular‐weight silicones. The siloxane is converted into solid forms, either masterbatch pellets or powders, that are easy to feed, or mix, into plastics during compounding, extrusion, or injection molding. Ultra‐high‐molecular‐weight siloxanes can be compounded into masterbatch pellets at higher siloxane concentrations than previously possible, e. g., up to 50%. They impart improved processing and release, lower coefficient of friction, and broader performance latitude compared to conventional lower‐molecular‐weight silicones. These benefits can be delivered at reduced siloxane levels with increased concentration at the surface interface with a new functionalized UHMW siloxane which provides unique surface segregation characteristics. Ultra‐high‐molecular‐weight siloxanes have been formulated into powders that can also act as processing aids and mechanical property modifiers for highly filled polymers such as fire‐retardant systems. This paper uses polyolefins as a model. However, many of the effects shown in polyolefins have also been seen in other resin systems.     

Photobase‐generating new polyurethanes with oxime–urethane groups in the main chain

New polymeric photobase generators containing oxime–urethane groups were prepared by the polyaddition reaction of 2,4‐tolylene diisocyanate with terephthalaldehyde dioxime in the presence or absence of a polyol component to study the ability of these polymers to generate amines through the photolysis of oxime–urethane linkage. The amines induced the crosslinking of poly(glycidyl methacrylate), as proved by the variation of the amount of the insoluble fraction of polymer films with the heating temperature and/or irradiation time. UV and IR absorption spectra indicated that the thermal crosslinking of poly(glycidyl methacrylate) was catalyzed by the photogenerated amines. The photobehavior of the polymers was followed by a reduction of the absorption band at 290 nm, which was characteristic of oxime–urethane groups, as a function of the UV irradiation time. Blue fluorescence was visualized by the treatment of irradiated films with fluorescamine. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2324–2332, 2004     

High‐contrast,high‐sensitivity aqueous base‐developable polynorbornene dielectric

The impact of multifunctional epoxy‐based additives on the crosslinking, photolithographic properties, and adhesion properties of a tetramethyl ammonium hydroxide developable, polynorbornene (PNB)‐based dielectric was investigated. Three different multifunctional epoxy additives were investigated: di‐functional, tri‐functional, and tetra‐functional epoxy compounds. The tetra‐functional epoxy crosslinker enhanced the UV absorbing properties of the polymer at 365 nm wavelength. It was found that the epoxy photo‐catalyst could be efficiently activated without a photosensitizer when the tetra‐functional epoxy was used. The polymer mixture with additional (3 wt %) tetra‐functional epoxy crosslinker and without a UV sensitizer showed improved sensitivity by a factor of 4.7 as compared to a polymer mixture containing the same number of equivalents of non‐UV sensitive epoxy with a UV sensitizer. The contrast improved from 7.4 for the polymer mixture with non‐UV absorbing epoxy and a UV sensitizer to 33.4 for the new formulation with 3 wt % tetra‐functional epoxy and no UV sensitizer. The addition of the tetra‐functional epoxy crosslinker also improved the polymer‐to‐substrate adhesion, which permitted longer development times, and allowed the fabrication of high‐aspect‐ratio structures. Hollow‐core pillars were fabricated in 96‐µm thick polymer films with a depth‐to‐width aspect‐ratio of 14 : 1. The degree of crosslinking in the cured films was studied by nanoindentation and swelling measurements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

UV‐Triggered Optical Response and Oxygen Scavenging Ability of a Water‐Soluble Poly(N,N‐dimethylacrylamide‐co‐2‐vinylbenzylanthraquinone) Copolymer

A vinyl‐modified anthraquinone (AQ) derivative (Vinyl‐AQ) is synthesized through a palladium‐mediated Suzuki coupling reaction between vinylphenylboronic acid and 2‐chloromethylanthraquinone and, subsequently, copolymerized with N,N‐dimethylacrylamide (DMAM) through free radical copolymerization in organic solvent. The chemical structure of the resulting water‐soluble copolymer, P(DMAM‐co‐AQ), is verified using techniques such as proton nuclear magnetic resonance, attenuated total reflection‐infrared spectroscopy, thermogravimetric analysis, and UV–vis spectroscopy. The evolution of the oxygen scavenging abilities of aqueous P(DMAM‐co‐AQ) solutions after UV irradiation is monitored as a function of UV irradiation time, concentration of AQ moieties, and pH. The copolymer is proved an effective UV‐triggered oxygen scavenger, leading to dissolved oxygen contents below 1 ppm for the optimized experimental conditions. This behavior is related with the appearance of novel chemical species with interesting optical properties, as suggested by the respective evolution of the UV–vis absorption and photoluminescence spectra after UV irradiation.     

Fluorinated epoxides as surface modifying agents of UV‐curable systems

Two commercially available epoxy‐fluorinated monomers, 3‐(perfluorooctyl)‐1,2‐propenoxide and 3‐(1H, 1H, 9H‐hexadecafluorononyloxyl)‐1,2 propenoxide, were used as modifying additives for UV curable systems. These two fluorinated monomers were mixed, in small amounts (less than 1% w/w) with a hydrogenated epoxy monomer 1,4‐cyclohexanedimethanol‐diglycidyl ether. The mixtures were coated on glass substrate and UV‐cured, giving rise to transparent films. Notwithstanding their very low concentrations, the fluorinated monomers caused a change in the surface properties of the films, without changing their curing conditions and their bulk properties. The air side of the coatings became highly hydrophobic, while the substrate side was unmodified. As shown by XPS measurements, the fluorinated monomers were able to concentrate selectively on the air side of the films, forming a fluorinated layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1524–1529, 2003     

Green composites of organic materials and recycled post‐consumer polyethylene

Addition of organic fillers to post‐consumer recycled plastics can give rise to several advantages. First of all, the cost of these fillers is usually very low, the organic fillers are biodegradable contributing to an improved environmental impact and, last but not least, some mechanical and thermomechanical properties can be enhanced. Organic fillers are not widely used in the plastic industry although their use is increasing. Bad dispersion into the polymer matrix at high‐level content and poor adhesion with the matrix are the more important obstacles to this approach. In this work various organic fillers have been used with a post‐consumer plastic material originating from films for greenhouses. The properties of these green composites have been compared with those of materials filled with a conventional inorganic filler. The organic fillers cause slightly worse processability, due to an increase of viscosity, an enhancement of the rigidity and of the thermomechanical resistance similar to that measured for the inorganic filler, while a reduction of the impact strength is observed. Copyright © 2004 Society of Chemical Industry     

Nanometer‐thick patterned conductive films prepared through the self‐synthesis of polythiophene derivatives

The development of flexible electronics requires the patterning of conductive and active semiconductor films. Although inorganic materials such as indium tin oxide and metal nanoparticles have high conductivity and transparency, their poor interfacial adhesion with organic layers, lack of flexibility, high weight and high capital costs are drawbacks. In contrast, organic conducting polymers have great potential for use in commercial flexible electronic applications because of their low production costs, environmental stability and acceptable conductivities. A UV‐curable photoresist containing hydroxyl groups was prepared from a mixture of a photoinitiator, epoxy‐acrylate resin, hydroxyethyl methacrylate and tripropylene glycol diacrylate. Patterns having line widths/spaces of 100/100 µm and 10/5 µm were fabricated on a poly(ethylene terephthalate) (PET) substrate using lithography techniques. (3‐Methyl‐3,4‐dihydro‐2H‐thieno[3,4‐b]dioxepin‐3‐yl)methanol (ProDOT‐OH) was self‐synthesized through urethane linkages onto the surface of the patterned photoresist on the PET film, which was then dipped into a solution of another monomer, 3‐thienylethoxybutanesulfonate (TEBS), and initiator and polymerized in situ to form conductive poly(ProDOT‐OH‐co‐TEBS) films covering the surface of the patterned resist. The optimal conductivity of the poly(ProDOT‐OH‐co‐TEBS) films was ca 90 S cm^?1 with an optical transparency of ca 70%. A new bottom‐up technique has been developed for the preparation of patterned organic transparent conductive films: self‐synthesis of the monomer using urethane‐forming reactions and subsequent in situ polymerization. The conductivity of the films can be controlled by the polymerization reaction time and the resolution of the pattern. These conductive patterned films might be applicable to the manufacture of industrial touch panels or chemical/biological sensors. Copyright © 2009 Society of Chemical Industry     

Ultraviolet‐curing behavior and mechanical properties of a polyester acrylate resin

Ultraviolet (UV) curing technology has been widely used in many applications because it has several distinct advantages compared to solvent‐based processes or thermal‐curing technology. The effects of photoinitiator types and their contents as well as reactive diluent types and their contents on the UV‐curing behavior and mechanical properties of a UV‐curable polyester acrylate resin were investigated in this study. Three photoinitiators, Irgacure 184, Darocur 1173, and benzophenone, were used in this study. Hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylol propane triacrylate were used as reactive diluents to modify the properties of the acrylate resin. The change of chemical structure during UV curing was monitored by FTIR. A universal testing machine was used to measure the tensile properties of various UV‐cured acrylate films of different compositions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3921–3928, 2004     

Pyrene‐anchored ZnO nanoparticles through click reaction for the development of antimicrobial and fluorescent polyurethane nanocomposite

This work demonstrates the development of a multifunctional, antimicrobial and fluorescent polyurethane–ZnO hybrid nanocomposite coating with the aid of azide–alkyne click chemistry. Firstly, the surface of ZnO nanoparticles was successfully modified with 3‐azidopropyltriethoxysilane coupling agent. The azide‐terminated nanoparticles were then reacted with separately synthesized propargylpyrene in order to obtain pyrene‐anchored ZnO nanoparticles. The size of the modified nanoparticles was measured using dynamic light scattering and field emission scanning electron microscopy. Thermogravimetric analysis showed that the thermal stability of the nanoparticles decreased with surface modification. The intensities of UV absorption and fluorescence emission were improved with an increase of pyrene units on the ZnO surface. These nanoparticles were incorporated into a triazole‐rich hyperbranched polyurethane matrix in various weight percentages. It was observed that thermal stability and the intensity of UV absorption and fluorescence emission of the resulting polyurethane nanocomposite hybrid films were improved with loading of the modified nanoparticles. These hybrids are extremely resistant towards various bacterial and fungal attacks, which is attributed to the presence of the ZnO nanoparticles in the coatings. © 2014 Society of Chemical Industry     

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     

Influence of pigment properties on UV‐curing efficiency

The curable formulations containing monomer‐diacrylate, photoinitiator‐p‐methoxybenzoyldiphenylphosphine oxide/benzyldimethylketal, additive reactive‐triethylamine, and inorganic thermoresistant pigments‐white, red, green, and blue were cured by UV exposure films. A series of experiments was carried out to investigate the relationship between the particle size distribution of the inorganic pigment and the colorimetric and mechanical properties of the UV acrylic curable coatings. Pendulum hardness and appearance of the films depend on the content and particle size distribution of the pigment. Optimal particle size distribution and pigment content were established to obtain the best films concerning their pendulum hardness and chromatic parameters. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 247–252, 2007