Effect of Maleic‐Anhydride Grafting on the Physical and Mechanical Properties of Poly(L‐lactic acid)/Starch Blends

MA is grafted onto both PLLA and starch in an internal mixer in the presence of DCP in a one‐step reactive compatibilization process. The effect of maleation of MA on the physical and mechanical properties and morphology of the blends was assessed. The onset decomposition temperature of the PLLA/starch blends decreased as the starch content increases due to the lower thermal stability of starch and the low effect of the maleation reaction on the thermal stability of the blends. PLLA/starch blends without grafted MA showed higher crystallinity as the starch content increased. Reactive compatibilized blends with less than 20 wt% starch had higher storage modulus, indicating that the compatibility between the two phases was improved.

     

Production of bioethanol from waste money bills – A new cellulosic material for biofuels

Waste money bills that are no longer legal tender are non-recyclable and are usually destroyed. In this study, we used this cellulose-rich material for bioethanol fermentation for the first time. Glucose production was enhanced by using diluted H₂SO₄ during pretreatment. Different incubation periods were tested for saccharification and subsequent bioethanol fermentation. The highest yield of glucose (41.90 mg/ml) was shown to increase with 27.20% and 25.90% respectively by increasing the reaction period by 30 min and by increasing the acid concentration by 0.5%. Bioethanol production was enhanced by adding 0.4 mM benzoic acid under anoxic condition. In accordance with three different conditions, the highest amount of bioethanol (22.01 mg/ml) was obtained and bioethanol fermentation was increased by 59.38%, 110.02% and 64.13% respectively with 30 min of reaction periods, 0.5% of acid concentrations and under anoxic condition with benzoic acid. This procedure for the production of bioethanol from a waste material would reduce waste money bill management costs and make a profit from ethanol.     

Preparation and characterization of maleic anhydride‐g‐polypropylene/diamine‐modified clay nanocomposites

Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005     

Shelf‐life prediction of perilla oil by considering the induction period of lipid oxidation

Kinetic models for the induction period (IP) of lipid oxidation were developed to predict the shelf‐life of perilla oil during storage. The degree of lipid oxidation was measured in terms of peroxide values (PV). The perilla oil was stored in the dark at various temperatures. The IP was measured at the intersection point of two linear lines and in terms of time and PV at the IP. The IP was expressed by an Arrhenius‐like relationship. Before and after the IP, the reaction followed pseudo‐zero‐order kinetics. The oxidation degrees according to storage times were computed by considering the variables, IP and reaction rate constants. The prediction model equation that was developed to determine shelf‐life is more accurate than in previous studies. Conclusively, considering the IP of lipid oxidation is essential for predicting the shelf‐life of perilla oil and is expected to be applicable to other vegetable oils. Practical applications : In kinetic modeling for shelf‐life estimation in terms of lipid oxidation, induction period (IP) is rarely considered. Thus the estimation of peroxide values (PV) from such models might be inaccurate. The IP was observed in perilla oil oxidation and kinetic models involving the IP were developed. This work enables a better estimation of oxidation. Besides, a shelf‐life diagram of perilla oil has been constructed as a valuable tool for quality control in the food industry.     

Synthesis of liquid crystalline epoxy and its mechanical and electrical characteristics—curing reaction of LCE with diamines by DSC analysis

An aromatic liquid crystalline epoxy monomer based on biphenyl mesogen was synthesized and cured with three different aromatic diamines. The curing reaction characteristics were analyzed by DSC, and the data were introduced to the Kissinger equation to attain the kinetic parameters. Diglycidyl ether of 4,4′‐biphenyl (DGEBP)/4,4′‐diaminobiphenyl (DABP), and DGEBP/4,4′‐methylenediamine (MDA) systems showed an exotherm curing reaction after comelting of the monomers; the DGEBP/p‐phenylenediamine (PDA) system's curing reaction took place in the solid state without melting of monomers. The activation energy and preexponential factor for the DGEBP/DABP system were 55.6 kJ/mol and 4.0 × 10⁶ min^?1, respectively. Those values for DGEBP/MDA and DGEBP/PDA systems were 55.1 kJ/mol and 1.0 × 10⁶ min^?1 and 148.8 kJ/mol and 7.7 × 10¹⁹ min^?1, respectively. The rate constant at 100°C for DGEBP/PDA is 2 times higher than those for DGEBP/DABP and DGEBP/MDA, which have almost the same values. Strictly speaking, the rate constant of DGEBP/DABP is a little higher than that of DGEBP/MDA, and these results are in good agreement with the DSC curves. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2419–2425, 2002     

Preparation of core–shell type nanoparticles of diblock copolymers of poly(L‐lactide)/poly(ethylene glycol) and their characterization in vitro

Core–shell type nanoparticles of poly(L ‐lactide)/poly(ethylene glycol) (LE) diblock copolymer were prepared by a dialysis technique. Their size was confirmed as 40–70 nm using photon correlation spectroscopy. The ¹H‐NMR analysis confirmed the formation of core–shell type nanoparticles and drug loading. The particle size, drug loading, and drug release rate of the LE nanoparticles were slightly changed by the initial solvents that were used. The drug release behavior of LE core–shell type nanoparticles showed an initial burst during the first 12 h and then a sustained release until 100 h. The degradation behavior of LE block copolymer nanoparticles was divided into three phases: the initial rapid degradation phase, the stationary phase, and the rapid degradation phase until complete degradation. It was suggested that lidocaine release kinetics were predominantly governed by the diffusion mechanism in the initial burst phase and after that by both of the diffusion and degradation mechanisms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2625–2634, 2002     

Poly(L‐lactic acid) with added α‐tocopherol and resveratrol: optical,physical, thermal and mechanical properties

Poly(L ‐lactic acid) (PLLA) films containing various concentrations of two natural antioxidants, α‐tocopherol and resveratrol, were fabricated by a melt compounding and compression molding process. The influence of the antioxidants on the optical properties such as color and UV‐visible light transmission was analyzed. The thermal, mechanical, rheological and physical properties of PLLA films with added antioxidants were assessed. PLLA films with added α‐tocopherol and resveratrol showed a yellowish brown color and the lightness was influenced by the presence of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. PLLA films with added antioxidants were slightly more hydrophobic than neat PLLA. The combination effect of plasticizing and enhancement of the elastic modulus with differing concentrations of two antioxidants played a critical role in the mechanical and thermomechanical properties of PLLA films. The melt viscosity of the PLLA films with added antioxidants was substantially higher than that of neat PLLA. The higher melt viscosity and G′(ω) could be an indication of formation of entanglement between PLLA and the two antioxidants. Copyright © 2012 Society of Chemical Industry     

Molecular dynamics simulations and experimental studies of the thermomechanical response of an epoxy thermoset polymer

We report a detailed comparison between molecular dynamics predictions and experimental results for a wide range of thermo-mechanical properties of an epoxy resin system: diglycidyl ether of bisphenol A (DGEBA) cured with 3,3′ diamino-diphenyl sulfone (33DDS). A set of carefully designed and characterized experiments provides validation data for the simulations that predict the molecular structure and properties of the thermoset. Our results show that current state-of-the-art molecular dynamics simulations provide quantitative predictions for this epoxy system in its glassy state, including elastic moduli, coefficient of thermal expansion and specific heat. The glass transition temperature is also accurately predicted once a correction is included to account for the difference in cooling rates between the simulations and experiments. Our results also indicate that viscoelastic and thermal properties of the thermoset polymer in its rubbery state are more challenging to predict since the effect of timescales is not well understood.     

Effects of an external electric field on the collection efficiency of air filters: Filtration mechanisms with an external e-field

An external electric field was applied on the filter to improve its collection efficiency, and the collection efficiencies of the different filters under various conditions were evaluated. Dominant electrical filtration mechanisms for each condition were investigated using experimental and theoretical approaches. Four types of air filters were used as test filters: a charged fiber filter, a low-grade filter with 50% collection efficiency in the most penetration particle size (MPPS) zone, and two high-grade filters with more than 95% collection efficiency in the MPPS zone. Three different particle charge states—neutralized, single-charged and uncharged—were considered. For neutralized particles, the external electric field led to a 14.5%p. and 2.5%p. increase in the collection efficiencies of the low-grade filter and charged fiber filter, respectively. With the electric field, the collection efficiency of the low-grade filter increased by 30%p. for single-charged particles. The electric field also affected the collection efficiencies of the charged filter and high-grade filters, but the effect was not significant. For uncharged particles, the electric field did not lead to a remarkable increase in the collection efficiencies of any of the filters. Through experimental and theoretical analysis, it was found that the polarization force imposed on the charged fiber was the dominant factor for the charged fiber filter regardless of application of the external electric field. The Coulombic force imposed on the electric field was the dominant factor for the low-grade filter, while both the Coulombic and the polarization forces affected the collection efficiency of the high-grade filter.

Copyright © 2017 American Association for Aerosol Research     

Soft-, shape changing materials toward physicochemically powered actuators

A shape changing material (SCM) morphs its shape upon external stimulus, and it offers a design of complex 3-dimensional structures remotely, which can be potentially useful for biomedical tools, drug delivery, and soft robotics. To actuate such structures through a physicochemical stimulus, stimuli-responsive materials have been studied over the past few decades. Several SCMs have been reported by combining novel stimuli-responsive materials, micropatterning techniques and a unique actuation cue. In this review, we introduce a recent development in SCMs within the aspects of their materials and structures to describe how the materials can be designed and actuated on demand. Finally, we discuss the future direction and challenges for SCMs as physicochemically-powered actuators.