Extruded Biodegradable Cast Films from Polyhydroxyalkanoate and Thermoplastic Starch Blends: Fabrication and Characterization

PHA‐based extruded films were developed by blending PHAs with thermoplastic starch using extensive process engineering based on structure‐property correlations. Starch was destructurized and plasticized followed by melt‐blending with PHA and PBAT. Dynamic mechanical analysis coupled with Gibbs free energy values indicated that the starch plastic was performing the role of a dual compatibilizer in between the PHA and the PBAT phases in the blend. Aging, an inherent problem with starch‐based materials and PHA‐based materials, was effectively reduced by limiting the moisture uptake of the starch component, hindering the leaching of glycerol and inhibiting the secondary crystallization of the PHA component in the films.

     

十一烯酸/马来酸酐共聚物的制备与表征

以十一烯酸(UA)和马来酸酐(MAH)为原料,偶氮二异丁腈(AIBN)为引发剂,通过沉淀聚合的方法制备了十一烯酸/马来酸酐共聚物(UMA),研究了单体配比、引发剂用量及反应温度对共聚反应的影响,通过FT-IR、¹³C NMR、DSC分析和酸酐质量分数的测定对共聚物进行了表征。FT-IR和¹³C NMR结果表明：在实验条件下,十一烯酸(UA)与马来酸酐(MAH)发生了共聚反应。当反应温度为75 ℃、AIBN用量为0.75%时,随着MAH用量的增加,共聚物相对分子质量减小,得率和酸酐质量分数呈现先增大后略有减小的趋势,当UA与MAH的物质的量之比为40:60时共聚物的得率及酸酐质量分数均达到最大值,分别为61.78%和20.05%,与DSC曲线中玻璃化转变温度(T_g)的变化趋势基本一致,即当n(UA):n(MAH)为40:60,T_g达到最大值71.98 ℃。提高引发剂用量和反应温度有利于共聚反应的进行,但相对分子质量有所下降,因此可根据所需聚合物的性质来选择合适的反应条件。     

MA/EG与TBPA/EG聚酯化反应动力学

通过熔融缩聚反应对马来酸酐/乙二醇(MA/EG)和四溴邻苯二甲酸酐/乙二醇(TBPA/EG)两个聚酯化反应的动力学进行研究。考察了自催化条件下反应温度、原料配比对聚酯化反应速率的影响。在陈寿安模型的基础上,对反应级数的不同组合进行了比较研究。结果表明:1-1模型和实验结果吻合良好,且k_h[H₂O]为正值;温度越高,醇酸配比越大,则聚合反应程度越大。     

SMA接枝PHBA侧链液晶高分子的合成与性质

采用溶液缩聚法合成了苯乙烯－马来酸酐共取物接枝聚对羧基苯甲酸侧链液晶高分子,讨论了反应的接枝率和液晶侧链对高聚物热性质的影响。     

马来酸酐接枝茂金属聚乙烯制备及其粘接性能

以水为分散介质,茂金属聚乙烯为分散相,在过氧化苯甲酰引发下,制备了马来酸酐接枝茂金属聚乙烯(mPE-g-MAH)。研究了影响接枝率和凝胶率的主要因素。结果表明,在反应温度为80℃、反应时间为3h时,可以合成出无凝胶、接枝率为0.8%的mPE-g-MAH。通过DSC和XRD分析,表明接枝反应是在非晶区进行的,既没破坏聚乙烯分子骨架结构,又将极性单体接枝到聚乙烯分子链上。对接枝产物粘接性能测试显示:随接枝率增加,粘接性能提高,这主要是由于接枝产物中的极性基团与钢材表面间的化学键合作用。接枝率为0.76%的接枝产物的剪切强度和剥离强度分别由未接枝时的0.8MPa、0.22N/mm增加至7.9MPa、2.40N/mm。     

Synthesis and Biocompatibility of Maleic Anhydride Copolymers: 1. Maleic Anhydride–Vinyl Acetate,Maleic Anhydride–Methyl Methacrylate and Maleic Anhydride–Styrene

A series of maleic anhydride (MA)–vinyl acetate (VA), MA–methyl methacrylate (MM) and MA–styrene (S) copolymers were prepared and characterized. By employing various amounts of initiator, MA–VA, MA–MM and MA–S copolymers with molecular weights ranging between 18 000 and 219 000 were obtained. The ‘in vivo’ and ‘in vitro’ tests performed on K562 cellular cultures (human chronic myeloid leukaemia) and also on Westar rats (inoculated with the Walker 256 carcinosarcome) showed that, as a function of the molecular weight, the copolymers synthesized had a 50% in vitro cytotoxicity and a mean tumour regression of a maximum of 68%. © 1997 SCI.     

Reactive polymers in diagnostics: Syntheses and characterizations of nucleic acid probes and maleic anhydride-co-methyl vinyl ether polymers

Maleic anhydride-co-methyl vinyl ether copolymers were used as reactive polymers to link oligodeoxyribonucleotides (ODN) to make oligonucleotide-copolymer conjugates of potential applications in diagnostics. The anhydride moieties of the copolymers were used for the covalent binding, via the formation of a peptide bond, on reaction with DNA probes that were amino modified at the 5′ position. The best coupling yields were obtained by carrying out the reaction in a DMSO-borate buffer (95/5 volume ratio) mixture at high ionic strength. Copolymers and ODN-copolymer conjugates were characterized by size exclusion chromatography and multiangle laser light scattering detection. The average molecular weights of the formed conjugates were relatively high, in the 10⁶ g/mol range, resulting from the crosslinking of several copolymer molecules during coupling. Coupling DNA probes onto smaller molecular weight polymers did not result in the formation of very high molecular weight conjugates showing that copolymer chain interpenetration was a determining factor of the crosslinking process that occurs during the coupling reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2567–2577, 1997     

First-principles Study of Perovskite Ultrathin Films: Stability and Confinement Effects

In this first-principles study we investigate the atomic, electronic, and vibrational structure of BaZrO₃(001) ultrathin films and surfaces, using a hybrid functional and a local Gaussian-like basis set. The low-index nonpolar (001) surface is known to be the most stable. We considered both possible kinds of nonpolar terminations (BaO and ZrO₂) for the (001) surface. The systems were studied using a slab model. Ultrathin films were modeled using slabs with the number of atomic planes ranging from three to seven, whereas surfaces were modeled with much thicker slabs composed of 15 atomic planes. In order to estimate the Gibbs free energy at finite temperatures, lattice vibrational frequencies were also calculated. We found that phonons noticeably affect the relative thermodynamic stability of the two termination layers: while at room temperature the BaO termination has the lowest energy, at intermediate temperatures (500 K) both terminations can coexist, and at higher temperatures (900 K) the ZrO₂-terminated surface becomes the most stable. We considered the effect of two-dimensional confinement on the structural, electronic, and vibrational properties of these ultrathin films. We found these confinement effects to be short ranged, with the properties of three-plane films to be the only ones that noticeably differ from the bulk material. Finally, we briefly consider confinement effects in such ultrathin films containing neutral and fully charged oxygen vacancies (charge states 0 and +2). We show, in particular, how lattice vibrations affect the Gibbs formation energy of a neutral oxygen vacancy making it completely independent of the film thickness at high temperatures (1000 K), due to cancellation of enthalpy and entropy contributions.     

Polymer microspheres: Influence of composition and porosity on filtrate reduction from aqueous fluids

During the drilling and completion of oil wells, the drilling fluid flowing down the annulus can invade the rock formation, possibly causing irreversible damage to the reservoir. One of the main functions of these fluids is to form a film with low permeability on the borehole wall to prevent invasion of filtrate in the rock formation. Polymeric additives are increasingly used to control these infiltrations. Recent studies have shown the potential of using microspheres made of poly(methyl methacrylate‐co‐vinyl acetate) (PMMA‐co‐PVAc) with dimensions compatible with the size of the formation pores. In this study, PMMA and PMMA‐co‐PVAc polymers were synthesized by suspension polymerization, producing in the presence or absence of porogenic agents. The particles porosities influence the glass transition temperature, surface roughness and apparent density. The results also demonstrate that less rigid spheres with pores in their structure form a more efficient barrier against filtration to the rock formation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44484.     

Copolymerization of the pair maleic anhydride–dicyclopentadiene: I. Copolymerization and post‐copolymerization at high conversion

The present study describes the kinetic investigation of the complex binary copolymerization system maleic anhydride (MA)—dicyclopentadiene (DCPD). All syntheses were carried out in homogeneous solution; high conversions in soluble and linear copolymer are achievable when starting from an equimolecular monomer feed. Excess of DCPD would limit the attainable conversions, while surplus of MA would induce crosslinking of the copolymers. The findings of the thorough kinetic study were sustained by structural assessment from IR and NMR spectra recorded for various copolymers, both soluble and gels. Copyright © 2004 Society of Chemical Industry     

Effects of thermal treatment on the CO2 sorption of triblockcopolymers derived from polyimide and poly(methylmethacrylate)

ABA‐type triblock copolymers were synthesized using 4,4‐(hexafluoroisopropylidene) diphthalic anhydride‐2,3,5,6‐tetramethyl‐1,4‐phenylenediamine (6FDA‐TeMPD) and poly(methyl methacrylate) (PMMA). The films were characterized by determining the effects of different content ratios and thermal decomposition of PMMA block on CO₂ sorption properties. TGA results showed that a thermal labile block can be completely decomposed under a previously reported thermal condition. SEM results presented that the asperity was micro‐phase separation caused by the PMMA block content rate. Numerous pores with sizes of approximately 10 to 50 nm were detected on Block(28/72) and Block(10/90). The isotherms of all films fitted the dual‐mode sorption model, and CO₂ sorption decreased with increased PMMA content rate. Infinite‐dilution CO₂ solubility depended on the Langmuir's site of each polymer because S_H0/S₀ of PI and Block(PI/PMMA) varied from 0.84 to 0.92 CO₂ affinity was increased by thermal treatment as indicated by the higher b and S₀ values of thermally treated films than those of nontreated films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42208.     

Nanopaper: Thin Films Prepared from Polymeric Nanotubes

A novel mesoporous material (“nanopaper”) prepared from template‐synthesized, polyelectrolyte‐stabilized polymer nanotubes is reported. The stacked network of completely collapsed, flat nanotubes forms the porous structure, which has a water‐vapor permeability that can be tuned by the stabilizer. The transport mechanism is elucidated based on microscopy, thermal analysis, spectroscopy characterization, and mass‐transfer theory. The results suggest that the nanotube surface plays a key role in the through‐film transport process. This effect vanishes in the more open films formed from micro‐fibrillated cellulose having similar fibril diameters. Nanopaper mechanical properties are also reported. With a pore structure and functionality that can be varied, nanopaper is a promising functional membrane.

     

Processing and Characterization of Hexagonal Ferrite Thin Films from Organometallic Compounds

Thin films of BaFe₁₂O₁₉ were deposited on resistor-grade alumina by a chemical solution processing method involving the hydrolysis of a barium alkoxide and iron carboxylate. Conversion of the deposited organometallic precursor to an amorphous oxide was accomplished by a thermal decomposition/oxidation at 370°C. Subsequent development of the M-type hexagonal structure was accomplished with postannealing in air at temperatures in excess of 600°C. All films were characterized by scanning electron microscopy, X-ray diffraction, and magnetic measurements.     

Evaluation of CO2-philicity and thickening capability of multichain poly(ether-carbonate) with assistance of molecular simulations

Phenyl-centered tri-chain poly(ether-carbonate) (TMA-PEC), phenyl-centered double-chain poly(ether-carbonate) (TPA-PEC), and phenyl-centered four-chain poly(ether-carbonate) (TFA-PEC) were synthesized to act as CO₂ thickener. Their solubility in CO₂ was measured by cloud point pressure. In order to explore the material characteristics that affect the solubility, dynamic simulations were used to analyze intermolecular polymer interactions, and the interaction between polymers and CO₂. It was found that TPA-PEC and TMA-PEC has better solubility than TFA-PEC in CO₂ among the three polymers while the thickening effect is poor, TFA-PEC possess the best viscosity thickening effect while the solubility in CO₂ is unfavorable. The silicone unit 1,1,1,3,5,5,5-heptamethyl-3-(3-[oxiran-2-ylmethoxy] propyl)trisiloxane modified TFA-PEC (TFA-PEC-SAGE) combine good solubility and good thickening ability together. The molecular simulations show that TPA-PEC and TMA-PEC have weaker intermolecular interactions and TPA-PEC and TMA-PEC have stronger interaction with CO₂ which are beneficial to the solubility.     

The Fabrication and Characterization of Cellulose/Mesoporous Silica Composites Packaging Films with Adjustable Permeability by NMMO Technology

Cellulose-based composites containing various amounts of SBA-15 mesoporous silica were prepared by NMMO-technology, and their morphologies, mechanical properties, permeability for oxygen and water vapor were studied. The investigation suggested that both the modified and unmodified mesoporous silica materials can improve the elongation at break of the cellulose films. However, the incorporation of the mesoporous silica materials can reduce the tensile strength of the films, and the modified one has less effect on that than the unmodified one. The composites films with rational mechanical properties have adjustable oxygen permeability (7.90 × 10^?15–94.6 × 10^?15 cm³ · cm/cm² · s · Pa) and water vapor permeability (7.12 × 10^?13–4.10 × 10^?13 g · cm/cm² · s · Pa).     

Films made from poly(vinyl alcohol‐co‐ethylene) and soluble biopolymers isolated from municipal biowaste

Blends were obtained from poly(vinyl alcohol‐co‐ethylene) and water‐soluble biopolymers isolated from the alkaline hydrolysate of two materials sampled from an urban waste treatment plant: that is, an anaerobic fermentation digestate and a compost. The digestate biopolymers contained more lipophilic and aliphatic C and less acidic functional groups than the compost biopolymers. Evidence was obtained for a condensation reaction occurring between the biopolymers and the synthetic polymer. The thermal, rheological, and mechanical properties of the blends were studied. Films containing a low concentration (ca. 6–7%) of biopolymers exhibited up to three times higher yield strength than the neat synthetic polymer. The films' properties were found to be dependent on the concentration and nature of the biopolymers. The results offer a scope for investigating biopolymers sourced from other biowastes and for a better understanding of the reasons for the observed effects and exploiting their full potential for modifying or replacing synthetic polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41359.     

Polymerization of ϵ‐caprolactone with maleic anhydride: Synthesis and characterization

High‐molecular‐weight polymers of ϵ‐caprolactone (CL) and maleic anhydride (MA) with anhydride group content of about 1% wt have been synthesized and studied. The polymerization reaction was carried out in bulk under nitrogen atmosphere. Stannous octoate (Sn(oct)₂), and 2,2'‐azobisisobutyronitrile (AIBN) were used as a catalyst and an initiator, respectively. A two‐level design of experiments was used to study the effect of various conditions on the characteristics of the copolymer. Reaction time, temperature, and concentration ratio of various reactants (two monomers, monomer to catalyst, and monomer to initiator) were the independent variables used, and the dependent variables included the molecular weight and the anhydride content in the polymer. Nuclear magnetic resonance (NMR) studies indicate that the succinic anhydride units were incorporated individually either to the polymer chain end or backbone. Anhydride content in the polymer and gel permeation chromatograph (GPC) studies indicate that the maleic anhydride acts as the true initiating species rather than as a comonomer in the system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3189–3194, 2000     

Synthesis,characterization and use of polymer‐supported phase transfer catalyst in organic reactions

A polymer‐supported (PS) phase transfer catalyst, polyethylene‐g‐quaternary ammonium salt (PE‐g‐Q_N⁺), is prepared through a three‐step graft copolymerization of maleic anhydride (MAn) onto polyethylene (PE) by photochemical method using 1% benzophenone (Bz) as photosensitizer. Post grafted acid hydrolysis of polyethylene‐g‐maleic anhydride (PE‐g‐MAn) results in the preparation of PE‐g‐succinic acid which on further treatment with tetrabutylammonium bromide (TBAB) under basic conditions in tetrahydrofuran (THF) gives PE‐g‐Q_N⁺. Optimum conditions pertaining to maximum percentage of grafting have been evaluated as a function of concentration of maleic anhydride, amount of photosensitizer, and time of reaction. Maximum percentage of grafting (25%) was obtained using 3.57 mol of MAn and 0.5 mL of 1% Bz in 120 min. The PE and graft copolymers, PE‐g‐MAn, and PE‐g‐Q_N⁺ were characterized by FTIR Spectroscopy and thermogravimetric analysis (TGA). The ionic nature of quaternary ammonium salt, PE‐g‐Q_N⁺ has also been confirmed by conductance measurements. PE‐g‐Q_N⁺ reagent have been used successfully for polymerization, amidation, and esterification reactions. The products obtained were characterized by FTIR and H¹NMR spectral methods. The reagent was reused for the further reactions and it was observed that the polymeric reagent polymerize, amidate, and esterificate the compounds successfully but with little lower product yield. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A water‐soluble acrylamide hydrophobically associating polymer: Synthesis,characterization, and properties as EOR chemical

A water‐soluble acrylamide hydrophobically associating terpolymer for polymer flooding was successfully synthesized via free radical polymerization using acrylamide (AM), acrylic acid (AA), and N,N‐divinylnonadeca‐1,10‐dien‐2‐amine (DNDA) as raw materials. The terpolymer was characterized by IR spectroscopy and fluorescence spectra. Compared with partially hydrolyzed polyacryamide (HPAM), the terpolymer showed a stronger link and better dimensional network structure under the environmental scanning electron microscope (ESEM). The results of rheology indicated that the terpolymer (AM‐NaAA‐DNDA) showed an excellent shear‐resistance in high shear rate (1000 s^?1) and remarkable temperature‐tolerance (above 110°C). The salt‐resisting experiment revealed that this terpolymer had a better anti‐salt ability. According to the core flooding test, it could be obtained that oil recovery was enhanced more than 15% under conditions of 2000 mg/L terpolymer in the mineralization of 8000 mg/L at 60°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of poly(vinylidene fluoride) flat sheet membranes prepared in various ratios of water/ethanol for separator of li‐ion batteries: Morphology and other properties

PVDF, poly(vinylidene fluoride), membranes were prepared and investigated by a scanning electron microscope, a universal testing machine, and capillary porometer for its potential use as a separator in lithium ion batteries. The membranes were prepared by phase inversion with different polymer types, concentrations of solution, amounts of additive, and nonsolvent ratios of water/ethanol. The morphology of membranes is affected by the ratio of both the coagulation bath (water/ethanol) and a low molecular weight additive (polymer/solvent/additive). The results showed that significant variations in the membrane were detected when adding an additive to the casting solution or ethanol to the coagulation bath. With an increased concentration of ethanol, the upper structure was found to be transformed into a sponge‐like arrangement. In the case of Solef®1015 of the same polymer concentration, despite the higher molecular weight of 1015, a relatively small sized nucleus is formed, resulting in a denser network and relatively uniform membrane structure being formed. Mechanical testing showed that the tensile strength of the PVDF membranes increased when added to a 25 wt % ethanol coagulation bath, whereas it is decreased when added to higher concentrations of ethanol in the bath or additives in the casting solution. In a bath condition of water/ethanol = 75/25 wt % (Bath no. 2), the value of tensile strength is 7.11 and 7.52 MPa, for Solef®6010 20 wt % and Solef®1015 17 wt %, respectively. The thickness of the prepared membrane is 21–34 μm and the porosity is up to 50%. The electrolyte absorption changes of the fabricated membranes at different conditions are measured from 151 to 223 ± 15%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011