Bitter potato starch-based film enriched with copaiba leaf extract obtained using supercritical carbon dioxide: Physical–mechanical,antioxidant, and disintegrability properties

Films based on bitter potato starch (BPS) and its blends with chitosan (BPS-Ch) or soy protein isolate (BPS-SPI) loaded with copaiba leaf extract (E) are prepared via the casting method. The physical–mechanical and antioxidant properties of the as-prepared films are compared with those of a control. Moreover, the half-maximal degradation (t₅₀) of the prepared films is calculated by fitting the Hill model to disintegrability kinetic data. Among the analyzed films, BPS-Ch-E exhibits the lowest (p < 0.05) solubility in water and opacity, strongest water vapor-barrier (3.58 × 10⁻¹¹ g m⁻¹ s⁻¹ Pa⁻¹), and highest tensile strength and elongation at break. The Fourier transform infrared spectra of BPS-Ch-E and BPS-SPI-E demonstrate new peaks at 1550, 1239, and 1070 cm⁻¹ corresponding to N H and C O stretching. The BPS-E and BPS-Ch-E surfaces are devoid of scratches and phase separation. The incorporation of E significantly increases the antioxidant activity of the films. BPS-SPI-E and BPS-Ch-E demonstrate the lowest (t₅₀ ≈ 1.4 days) and highest (t₅₀ ≈ 3.5 days) disintegration rates, respectively, among the prepared films. E loading facilitates the development of films possessing beneficial physical–mechanical and antioxidant properties as well as rapid disintegrability, enabling their potential application as a eco-friendly packaging material.     

Type transition in onset condition of turbulent fluidization

The type transition in onset condition of turbulent fluidization in gas fluidized beds was investigated to obtain the relation representing more precise roles of physical properties of gas and solid particles. The type transition in onset condition of turbulent fluidization occurs at Archimedes number of 20.87 by type transition of bubble breakup. The maximum stable bubble diameter (d _bmax ) is greater than the equilibrium bubble diameter (d _beq ) in the region, Ar< 20.87, but d_beq>d _bmax in the region, Ar>20.87. Therefore, the onset of turbulent fluidization is determined in the region, Ar<20.87, by d _beq and in the region, Ar>20.87, by d _bmax as the limit of bubble growth. The uc decreases in the region, Ar<20.87, but increases in the region, Ar>20.87 as temperature increases.     

Experimental study on fire properties of interior materials used in low‐floor light‐rail trains

In this work, cone calorimeter tests were conducted to investigate fire properties of interior materials (floor covering [FC], aluminum plate covered with paint [APCP], light diffuser [LD], and gel coat [GC]) used in low‐floor light‐rail trains. Ignition time (t_ig) of each material decreases with the increase of radiative heat flux. The decreasing order of the four samples by ignition time under the same radiative heat flux is LD > APCP > FC > GC. The heat release rate (HRR), peak value of HRR (PHRR), time from ignition to PHRR (t_p), fire growth rate index (FIGRA), and fire growth index (FGI) rise with the increasing radiative heat flux. For the FC, LD, and GC, single HRR peak is observed in the HRR history while three peaks are observed for APCP. For PHRR, LD > FC > APCP > GC, while for t_p, GC < FC < APCP < LD. Under most conditions, the FIGRA and FGI of the FC is the highest among the four materials. Results of this work are beneficial to evaluate fire hazard of low‐floor light‐rail train and determine the emphasis of fire prevention.     

Preparation and characterization of styrene/styryl–polyhedral oligomeric silsesquioxane hybrid copolymers

BACKGROUND: Organic–inorganic nanocomposites were prepared by copolymerization of various monomers and polyhedral oligomeric silsesquioxane (POSS) derivatives. Preliminary results showed that styrene/styryl–POSS copolymers could be obtained using CpTiCl₃ catalyst. In the work reported here, the copolymerization of styrene and styryl‐substituted POSS was studied in detail for a more effective catalyst, Cp*TiCl₃. RESULTS: The glass transition temperature (T_g) of the copolymers prepared increased with increasing POSS content. The degradation temperature (T_d) of the copolymers was 60 °C higher than that of syndiotactic polystyrene under nitrogen. Although the thermal properties were improved by incorporation of POSS, the catalytic activity decreased with POSS content. The racemic triad and syndiotactic index of the copolymers decreased with increasing POSS content. Gel permeation chromatograms of the copolymers exhibited multimodal distribution due to the presence of multi‐active centres, which were formed by interaction of Ti with the POSS siloxane linkage. CONCLUSION: With the incorporation of POSS, the thermal properties of polystyrene were improved. The styrene/styryl–POSS copolymers are formed through the various active sites arising from the interactions of Ti with POSS. Copyright © 2008 Society of Chemical Industry     

Can the gel point of a cross-linking polymer be detected by the G′ – G″ crossover?

Dynamic mechanical measurements allow direct determination of the instant at which a network polymer gels. In such an experiment, the evolution of G′(t,ω₀) and G″ (t,ω₀) is measured in small amplitude oscillatory shear as a function of cross-linking time t. The frequency ω₀ is kept constant throughout. At the beginning of the experiment, G″ is orders of magnitude larger than G′, and at completion of reaction, this order is reversed. It recently has been suggested by Tung and Dynes that the gel point (GP) might occur at the time at which G′ and G″ cross each other. However, there is much dispute whether GP occurs exactly at the crossover or just somewhere in its vicinity. This study resolves the dispute by modeling the rheological behavior at GP: There is only one class of network polymers for which GP coincides with the crossover. This class of polymers exhibits, when reaching GP, power law relaxation G(t) ～ t_?n with a specific exponent value n = 1/2. Examples are stoichiometrically balanced network polymers and networks with excess cross-linker, however, only at temperatures much above the glass transition. Otherwise, the power law behavior would be masked by vitrification. Power law relaxation seems to be property of polymers at GP in general. However, some polymers have a different exponent value, n ≠ 1/2, in which case the crossover occurs before GP (for n < 1/2) or after GP (for n > 1/2); i.e. the crossover cannot be used for detecting GP. While there are no networks known to us with n < 1/2, recent experiments showed that network polymers that are lean on cross-linker exhibit power law relaxation with n > 1/2. A new method is suggested for measuring GP of these imbalanced networks.     

A novel hybrid functional nanoparticle and its effects on the dielectric,mechanical, and thermal properties of cyanate ester

A novel hybrid functional nanoparticle (denoted POSS‐MPS) was synthesized by aminopropyl‐functionalized mesoporous silica (AP‐MPS) with glycidyl polyhedral oligomeric silsesquioxane (G‐POSS). The G‐POSS was employed as molecular caps to envelop the MPS and improve the interaction with the polymer matrix. The POSS‐MPS hybrids were designed to improve the properties of cyanate ester (CE) without affecting its inherent properties. The POSS‐MPS/CE composites exhibited excellent improvement in dielectric properties, mechanical properties, and thermal properties due to increase of voids volume in the composites and reinforcement of interface interaction between organic and inorganic phase. The dielectric constant (κ) and loss factor (tan δ) of composites with 4 phr of POSS‐MPS reduced to 2.78 and 0.008 in comparison to pure CE with the value of 3.27 and 0.012, respectively. Moreover, the composites exhibited 14.3, 4.9, 57.5, and 8.7% enhancement in flexural strength, flexural modulus, impact strength, and glass transition temperature (T_g) in comparison to pure CE, respectively. The results manifested that introduction of POSS‐MPS into CE exhibited toughening and reinforcing effects on the composites. POLYM. COMPOS., 37:2142–2151, 2016. © 2015 Society of Plastics Engineers     

Terminal settling velocity and drag coefficient of biofilm‐coated particles at high Reynolds numbers

The drag force (F_d) on bio‐coated particles taken from two laboratory‐scale liquid–solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (u_t) and Reynolds numbers (Re_t) of particles observed were higher than reported in the literature. Literature equations for determining u_t were found inadequate to predict drag coefficient (C_d) in Re_t > 130. A new equation for determining F_d as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm‐coated particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Re_t of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Dynamic rheological properties of polyetherimide/polyetheretherketone/liquid crystalline polymer ternary blends

The dynamic rheological properties of poly(etherimide)/poly(etheretherketone)/liquid crystalline polymer (LCP) ternary blends were measured in order to correlate these properties with the morphology obtained after extrusion. The viscosity radio, η_d/η_m, where η_d = disperse phase viscosity and η_m = matrix viscosity, had to be redefined. Below 50 wt% LCP, η_d = η_LCP, η_m = η_PEEK+PEI and η_d/η_m < 1. Above 50 wt% LCP, η_d = η_PEEK+PEI, η_m = η_LCP and η_d/η_m > 1. Fibrillar morphologies were obtained in both cases, except below a concentration of 20 wt% LCP. At low concentrations of LCP the ternary blends had lower viscosities than the component polymers, showing a flow promotion effect of the LCP on the PEI- and PEEK-rich phases.     

High‐Speed Preparation of <111>‐ and <110>‐Oriented β‐SiC Films by Laser Chemical Vapor Deposition

Highly oriented <111> and <110> β‐SiC films were prepared on Si(100) single crystal substrates by laser chemical vapor deposition using a diode laser (wavelength = 808 nm) and HMDS (Si(CH₃)₃–Si(CH₃)₃) as a precursor. The effects of laser power (P_L), total pressure (P_tot), and deposition temperature (T_dep) on the orientation, microstructure, and deposition rate (R_dep) were investigated. The orientation of the β‐SiC films changed from <111> to random to <110> with increasing P_L and P_tot. The <111>‐, randomly, and <110>‐oriented β‐SiC films exhibited dense, cauliflower‐like, and cone‐like microstructures, respectively. Stacking faults were observed in the <111>‐ and <110>‐oriented films, and aligned parallel to the (111) plane in the <111>‐oriented film, whereas they were perpendicular to the (110) plane in the <110>‐oriented film. The highest R_dep of the <111>‐oriented β‐SiC film was 200 μm/h at P_tot = 200 Pa and T_dep = 1420 K, whereas that of the <110>‐oriented film was 3600 μm/h at P_tot = 600 Pa and T_dep = 1605 K.     

Novel phenyl‐POSS/polyurethane aqueous dispersions and their hybrid coatings

A facile and rapid preparation of 3‐(2‐aminoethylamino)propylheptaphenylPOSS (AA‐POSS), a special phenyl‐POSS that contains two functional amino groups (Scheme 1), is demonstrated by the corner‐capping method. Then AA‐POSS forms a series of novel phenyl‐POSS/PU aqueous dispersions. The structure of AA‐POSS has been confirmed by ¹H, ¹³C, ²⁹Si NMR, and ESI‐MS. The POSS/PU hybrid films are studied by Fourier transform infrared spectrometer (FT‐IR), gel permeation chromatography (GPC), scanning electron microscope (SEM), X‐ray diffraction (XRD) spectra, differential scanning calorimetry (DSC) analysis, and thermal gravimetric analyzer (TGA). FT‐IR and GPC are conducted to validate the chemical structure of the hybrid PU. The properties of hybrid films display significant changes with notable increases in T_g, thermal properties, tensile strength, as well as surface hydrophobicity. These changes are attributed to the incorporation of novel POSS into PU. Moreover, these significant material property enhancements are achieved at low levels of POSS incorporation (only 4%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1611–1620, 2013     

Oxygen barrier and enthalpy of melting of multilayer EVOH films after pressure‐assisted thermal processing and during storage

Pressure‐assisted thermal processing (PATP) is an advanced thermal process involving application of elevated pressures above 600 MPa on a preheated food for a holding time of 3 to 5 min, causing the volumetric temperature of food to increase above 100°C, to inactivate bacterial spores and enzymes. This study evaluated the influence of PATP on two state‐of‐the‐art multilayer EVOH films. Flexible pouches containing water as the food simulant were made from the two films and processed at 680 MPa for 3 min at 105°C and 680 MPa for 5 min at 100°C. Each film was investigated for its oxygen transmission rates (OTRs), melting temperature (T_m), enthalpy of melting (ΔH), and overall crystallinity before (control) and after processing. The changes in OTRs and total ΔH of the two films were also analyzed during a storage period of 240 days in ambient conditions after processing. Results showed a significant (P < 0.05) increase in the OTRs of the two films after PATP. However, PATP did not cause a significant (P > 0.05) change in the T_m and ΔH of the two films. The overall crystallinity of film A decreased, but improved slightly for film B after PATP. A recovery in the OTRs of the two films occurred during storage. The films also showed changes in the total ΔH measured during the storage period, which was used to explain the changes in the oxygen barrier properties. The OTR of both films remained below 2 cc/m² day, which is required in packaging applications for shelf‐stable foods with a 1‐year shelf life. This work demonstrates the advantages of using multilayer films containing EVOH as the barrier layer in PATP applications to produce shelf‐stable foods. This work also highlights the advantage of, DSC analysis for studying the physical ageing of polymers during storage. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Application of paraffin and silver coated titania nanoparticles in polyethylene nanocomposite food packaging films

In this work, 3% and 5% TiO₂/Ag nanoparticles were dispersed in low‐density polyethylene through melt blending process, and subsequently nanocomposite films were prepared by hot pressing. Paraffin was used for the first time in this work as compatibilizer agent. The effect of TiO₂/Ag nanoparticle content, as well as compatibilizer dosage on the antimicrobial, morphological, mechanical, and optical performance of the nanocomposite films was investigated. Improved mechanical properties of the nanocomposite films were found on using paraffin as compatibilizer in comparison with the neat low‐density polyethylene (LDPE) films. The optical study results also showed that the addition of TiO₂/Ag to the LDPE films does not drastically change the film appearance other than making them more reddish. The fabricated nanocomposites presented in this study could be a suitable choice for food packaging (subject to further investigation of the food packaging behavior). The results showed that both TiO₂/Ag nanoparticle and compatibilizer are needed to prevent the bacteria growth in the film. The best result was obtained by using 5% nanoparticle and 4% paraffin compatibilizer where the bacteria growth rate was significantly reduced by 95%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45913.     

Synthesis and characterization of organic–inorganic hybrid polymers with a well‐defined structure from diamines and epoxy‐functionalized polyhedral oligomeric silsesquioxanes

A new class of organic‐inorganic hybrid polymers with well‐defined structure was prepared by reacting diepoxyhexavinyl polyhedral oligomeric silsesquioxanes (DehvPOSS) with diamines of different chain lengths. The structures and properties of these hybrid polymers were well characterized by FTIR, ²⁹Si‐NMR, GC‐MS, and TGA. A modeling characterization was employed to help identify the structures of organic tethers linked between the POSS cages. The results indicated that at the stoichiometric ratio of DehvPOSS to diamine, well‐defined organic–inorganic hybrid polymers with controlled variation of the organic tether architecture can be made, and each organic tether connected four POSS cages. Thermal stability (T_dec) increased with an increase in the tether length of the diamine molecules, and the highest T_dec was obtained with butanediamine (rather than propanediamine or ethanediamine) as the organic tether. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3730–3735, 2006     

Synthesis and liquid‐crystalline properties of poly(4‐vinylpyridinium) bromides N‐substituted with dialkyloxyterphenyl groups

Poly(4‐vinylpyridine)s (P4VPs) fully and partially quaternized with dialkyloxyterphenyl groups were synthesized and characterized. These new polymers developed both liquid‐crystalline (LC) properties and a light emission (luminescence) in the blue region. The mesomorphic behavior of the polymers was initially characterized by differential scanning calorimetry and polarizing optical microscopy and was further corroborated by X‐ray diffraction analyses. The X‐ray diffraction patterns showed in the low‐angles region several equidistant diffraction peaks (d₀₀₁, d₀₀₂, d₀₀₃, …) and in the wide‐angles region a broad peak typical of nonordered mesophases. From d₀₀₁ and the length of the monomers, we deduced that the molecular arrangement in the mesophase corresponded to a double‐layered stacking of molecules with mesogens tilted with respect to the smectic plane and the backbones sandwiched between. In this arrangement, the different parts of mesogens are segregated from one another in layered domains. The longer smectic periods observed for copolymers indicated that the nonsubstituted pyridine cycles were sandwiched between two smectic layers. The emission spectra of these polymers were characterized by a broad signal centered at 365 nm. The combination of LC properties with luminescence in the polymers is interesting for the preparation of thin films with aligned emitters, particularly for linearly polarized light emission. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis, characterization, and properties of chain terminated polyhedral oligomeric silsesquioxane-functionalized perfluorocyclobutyl aryl ether copolymers

A new class of perfluorocyclobutyl (PFCB) polymers covalently functionalized with polyhedral oligomeric silsesquioxane (POSS) is presented. Three discreetly functionalized POSS monomers possessing thermally reactive trifluorovinyl aryl ether (TFVE) were prepared in good yields. The POSS TFVE monomers were prepared by initial corner-capping of cyclopentyl (-C₅H₉), iso-butyl (-CH₂CH(CH₃)₂), or trifluoropropyl (-CH₂CH₂CF₃) functionalized POSS trisilanols with acetoxyethyltrichlorosilane followed by sequential acid-catalyzed deprotection and coupling with 4-(trifluorovinyloxy)benzoic acid. TFVE-functionalized POSS monomers were thermally polymerized with 4,4′-bis(4-trifluorovinyloxy)biphenyl or 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomers via a condensate-free, [2 + 2] step-growth polymerization. The polymerization afforded solution processable PFCB polymers with POSS macromer installed on the polymer chain ends. POSS monomers and their corresponding copolymers were characterized by ¹H, ¹³C, ¹⁹F, and ²⁹Si NMR, GPC, ATR-FTIR, and elemental combustion analysis. GPC trace analysis showed agreeable number-average molecular weight for various weight percent of cyclopentyl or iso-butyl and trifluoropropyl chain terminated POSS PFCB copolymers. DSC analysis showed the introduction of increasing POSS weight percent in the endcapped PFCB copolymers lowers the glass transition temperatures as high as 31 °C. On the other hand, the trifluoropropyl POSS endcapped PFCB polymer glass transition temperature was unaffected when copolymerized with the more fluorinated 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomer. TGA analysis of POSS PFCB copolymers showed step-wise decomposition of copolymers resulting from the initial degradation of the POSS cages at 297-355 °C in nitrogen and air which was confirmed by pyrolysis coupled with GC-MS. This initial weight loss was proportional to the weight percent of POSS incorporated into the polymer. The balance of decomposition was observed at 450-563 °C in nitrogen and air which is higher than the PFCB homopolymers in most cases. Polymer surface characterization was performed on spin cast transparent, flexible films. These composite films exhibited good POSS dispersion within the matrix PFCB polymer as was shown by TEM analysis.     

Dispersion at Single Unit TiO2 Nanoparticles Reduced Tg,Induced Chain Disentanglement and Reduced Tensile Modulus in Waterborne Acrylic Coatings

Spatially distributed TiO₂ nanoparticles induced an order of magnitude decrease of glass transition temperature, T_g, and chain disentanglement in waterborne acrylic coatings. Acrylic/TiO₂ coatings are synthesized in situ by batch emulsion polymerization. The copolymer is based on butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) with composition 56:42:2 mol%, and nano-TiO₂ (ca. 12 nm) is incorporated up to 3 wt% content. Transmission electron microscopy (TEM) showed that TiO₂ is dispersed at nearly single unit throughout the acrylic matrix. The nanoparticle reduced T_g and broadened the temperature range of the glass transition, δT_g. The considerable increase of δT_g suggests gradients of dynamics. Shear rheometry demonstrated that TiO₂ induced chain disentanglement, the rubbery modulus G_e decreased two orders of magnitude with only 1 wt% TiO₂ content thus increasing the packing length p (and the reptation tube diameter as d_t = kp, k > 1). Consequently, the tensile Young's modulus E decreased an order of magnitude, relative to the neat copolymer. The reduction of T_g, the slowdown of macromolecular dynamics, the chain disentanglement and the increase of d_t suggests dynamics modification due to intercalation of the entangled web by the TiO₂ nanoparticles, and these results may be ascribed to a nanoconfinement effect.     

The effect of hybrid nanoparticle additives on epoxy‐nanocomposite behavior and morphology

Amine modified polyhedral oligomeric silsesquioxane (POSS‐NH₂) was used to modify sodium montmorillonite (MMT) nanoclays for improved dispersion in epoxy resin. The dispersion of the clay particles was inspected using scanning electron microscopy, energy dispersive spectroscopy (EDS) and X‐Ray diffraction and the thermal properties compared using differential scanning calorimetry (DSC) and thermogravametric analysis. The introduction of the amine‐POSS was found to have a positive effect on the dispersion of the MMT clays and prevented agglomeration. The absence of clay agglomerates lead to an increase in glass transition temperature (T_g) from 44°C in the samples with the untreated clay up to 54°C in the samples with 10% additional POSS‐NH₂. The addition of POSS‐NH₂ initial increase of the weight loss (T_{d 5%}) but slowed down the rate of degradation due to the formation of an inert silica layer and eventually leading to an increased charyield. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study on the preparation of PU/HBP‐NH2 blend film and its properties

The blend films of polyurethane (PU) and amino‐terminal hyperbranched polymers (HBP‐NH₂) were prepared successfully by mixing HBP‐NH₂ solution and PU. The rate of moisture absorption and mechanical properties were determined. The results showed that the rates of moisture absorption and vapor permeability were improved from 0.34% to 7.51% and from 161 gm^?2 d^?1 to 879 gm^?2 d^?1, respectively. The addition of HBP‐NH₂ is helpful to improve the hygiene properties of PU films. Then, the structures of the blend films were characterized by IR, XRD, TG, and SEM at the same time. The results indicated that HBP‐NH₂ and PU had hydrogen‐bond interaction and a certain phase separation. The blend films had good heat stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41383.     

Diffusion of miscible polymers in multilayer films

Thermal and optical properties of multilayer films of miscible polyethyloxazoline (PEOx) and poly(styrene-co-acrylonitrile) have been studied as a function of time and temperature. Differential scanning calorimetry showed that the distinct, characteristic T_g's of the component polymers of the original films disappear after only short heating periods above T_g, and a single transition appears. The new transition region is broad at first, but narrows on subsequent heating. The measurement of light transmittance as a function of wavelength through the heat-treated films also confirms the diffusion of the miscible polymers and gives results which are comparable to the thermal measurements. Films from immiscible polymers of polystyrene and PEOx retain their properties after various heat treatments. A qualitative discussion of the diffusion process as examined by the thermal measurements is presented.     

Facile preparation and characterization of soluble aramid

It remains a problem to prepare cost‐effective aramid with good solubility via a simple method since the commercialization of aromatic polyamides such as Kevlar and Nomex by DuPont in 1960s. Herein, we report the facile preparation and properties of an aromatic polyamide copolymerized by 2,6‐naphthalene dichloride (26N‐COCl), 4,4′‐oxydianiline, and m‐phenylenediamine. The synthetic route is very facile and cost‐effective. The modified aramids possess excellent comprehensive properties. The polymers are soluble in some organics. Their thermal stabilities are excellent, with 5% weight loss temperatures (T_d,5%'s) in air higher than 460 °C and glass transition temperatures (T_g's) higher than 280 °C. These polymers are easily processed into films, fibers, and tubes. The products exhibit high strength. For example, the films have excellent mechanical strength, with a tensile strength up to 139 MPa, a tensile modulus up to 3.45 GPa, and an elongation of 11%. The films are also transparent and fluorescent. The overall properties are better than those of the commercial Nomex. The facilely prepared aramids with good solubility are very promising for commercial use. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46341.