Effects of inorganic nano‐particles on plasticizers migration of flexible PVC

The influences of nano‐particles (nano‐sized CaCO₃ and nano‐sized SiO₂) on plasticizers volatility, solvent extraction stability, and exudation stability of flexible PVC were studied. The results showed that nano‐particles could reduce migration of plasticizers, thus improved the ability of anti‐migration of flexible PVC. Further more, nano‐sized SiO₂ shows excellent property than nano‐sized CaCO₃ in resistance migration of plasticizers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Plasticizer migration in bloodmeal‐based thermoplastics

Tri‐ethylene glycol (TEG) is an effective plasticizer for many protein‐based thermoplastics because of its low volatility, however, partial miscibility with the protein matrix may still lead to some phase separation. Spatial variation of TEG concentration in bloodmeal‐based thermoplastics as a result of processing was investigated using synchrotron‐based FT‐IR micro‐spectroscopy. Although TEG forms strong hydrogen bonding with proteins, for the protein to fold into β‐sheets bound plasticizer must be released. TEG can then migrate, pooling into localized areas, rich in plasticizer. Further heating causes further migration towards the edge of plasticized bloodmeal particles where the TEG may evaporate. Thermo‐gravimetric analysis confirmed that loss of TEG by evaporation may occur at 120°C, given enough time for diffusion. Efficient mixing combined with a short residence time at elevated temperature mean significant plasticizer loss is unlikely during processing. However, it does limit long‐term use at elevated temperatures. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39969.     

Syntheses and properties of cross‐linked polymers from functionalized triglycerides

A number of functionalized triglycerides were synthesized from glyceryl trioleoate via epoxidation followed by reduction to give glyceryl tris(9‐hydroxy)trioleoate (a triol) or hydrolytic ring opening to obtain glyceryl tris(9,10‐dihydroxy)trioleoate (a hexaol). A selective monoepoxidation reaction of glyceryl trioleoate was also carried out and the resulting monoepoxide was hydrolyzed to give glyceryl 9,10‐dihydroxytrioleoate (a diol). Glyceryl tris(9‐hydroxy)trioleoate was brominated followed by displacement with sodium azide and reduction to give glyceryl tris(9‐amino)trioleoate (a triamine) and glyceryl tris[9‐(N‐isopropylamino)]trioleoate. These functionalized triglycerides were crosslinked with 1,4‐phenylene diisocyanate. The crosslinked polymers exhibit thermoset characteristics. Thermal analysis results suggest that the polymers are in amorphous states, and their thermal stability was significantly affected by crosslink degree. The crosslinked polymer derived from the diol retained 56% of its weight at 408°C, whereas the polymers derived from the aforementioned hexaol with higher crosslink degree retained only 36% of the original weight. Glass transition temperatures of these polymers range from ?1.0°C to 10.2°C. The thermal stable polymer, 12 , derived from the aforementioned diol exhibits a linear viscoelastic character and can be used as thermoplastics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structures and properties of waste silicone cross‐linked polyethylene de‐cross‐linked selectively by solid‐state shear mechanochemical technology

Waste silicone cross‐linked polyethylene (Si‐XLPE) recycling effectively by using solid‐state shear mechanochemical (S³M) technology was investigated to make the better performance thermoplastic polyethylene. To make this thermoplastic material, the cross‐linked structures of waste Si‐XLPE that was consisted of the siloxane bonds must be de‐cross‐linked selectively instead of the destruction of the material main chains. The properties of recycled Si‐XLPE materials were investigated by gel fraction measurements, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter, torque rheological measurements, scanning electron microscope (SEM) and thermogravimetric analyzer (TG). From the results, it could be seen that the cross‐linking bonds of the Si‐XLPE were destroyed selectively by S³M technology and the mechanochemical milling also played a significant role in improving the materials process‐ability and mechanical properties. Gel fraction measurements, GPC and FTIR showed that S³M technology could interrupt the cross‐linked structures of Si‐XLPE rather than the backbone chains by initiating the de‐cross‐linking reaction obviously; Torque rheological results further confirmed that the recycled Si‐XLPE materials gained better plastic characteristics and process‐ability after mechanochemical milling. Compared with the untreated Si‐XLPE, the tensile strength and elongation at break of Si‐XLPE samples after 10 cycles milling increased by 118.4% and 330.4%, respectively. J. VINYL ADDIT. TECHNOL., 25:149–158, 2019. © 2018 Society of Plastics Engineers     

Novel cross‐linked sericin films: Characterization and properties

In the present study, an attempt has been made to convert sericin into film form and further make it insoluble by forming sericin–aluminum metal complex using alum salt, which may lead to some extent of cross‐linking. After complex formation sericin becomes insoluble in warm water as well as thermal stability and tensile strength improves significantly with increasing alum content. Metal complexed sericin films show good antimicrobial property and both the pure and alum modified sericin (AM‐Sericin) films show a very good oil barrier property. But after complex formation moisture content and swelling percentage of sericin film decreases quite significantly with increasing aluminum concentration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41400.     

Effects of poly(1,2‐propylene glycol adipate) and nano‐CaCO3 on DOP migration and mechanical properties of flexible PVC

Nano‐CaCO₃ was used as nano‐scale filler and poly(1,2‐propylene glycol adipate) (PPA) was used as polymeric plasticizer in flexible poly(vinyl chloride) (PVC) sheets for the partial replacement of di(2‐ethyl hexyl) phthalate (DOP) in this paper. The effect of PPA and nano‐CaCO₃ on restraining DOP migration was evaluated via extraction tests. The results showed that the introduction of nano‐CaCO₃ can decrease the extraction rate of DOP in the PVC matrix. The tensile strength and elongation at break of CaCO₃‐1/PPA‐20/DOP‐30/PVC were similar to those of DOP‐50/PVC, and CaCO₃‐1/PPA‐20/DOP‐30/PVC exhibited the superior suppression of DOP migration compared with DOP‐50/PVC. Thermogravimetry analysis (TGA) indicated that the addition of nano‐CaCO₃ effectively improved the thermal stability of the nanocomposites. Therefore, the combination of PPA and nano‐CaCO₃ is an effective approach to suppress the migration of DOP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polyimides cross‐linked with amino group‐containing compounds

The commercially available linear polyimide Matrimid^® 9725 was crosslinked with amino groups containing both high‐molecular‐weight and low‐molecular‐weight compounds. The multi‐functional amine‐terminated hyperbranched polyimide precursor (hyperbranched polyamic acid), based on 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 4,4′,4″‐triaminotriphenylmethane, and its fully imidized form (amine‐terminated hyperbranched polyimide), bifunctional amine, 4,4′‐diaminodiphenylamine and trifunctional amine, 4,4′,4″‐triaminotriphenylamine, were used as the crosslinkers. Theoretically, 10% or 20% of the Matrimid imide groups was reacted with the amino groups of the crosslinking agent during the formation of the amide groups. The insoluble content (gel) in the final materials was very low at the crosslinking temperature of 80°C and was in the 55–90% range at the crosslinking temperature of 200°. The permeability coefficients of hydrogen, carbon dioxide and methane in the self‐standing, mechanically tough film (membrane) based on the combination of Matrimid and hyperbranched polyimide were approximately 30–45% higher compared with those in the membrane made of pure Matrimid at a comparable separating ability (selectivity). POLYM. ENG. SCI., 57:1367–1373, 2017. © 2017 Society of Plastics Engineers     

PVC中增塑剂迁移和抽出问题

讨论了聚氯乙烯（PVC）中增塑剂抽出和迁移的危害性和基本原理,重点介绍了影响增塑剂抽出和迁移的主要因素,如：增塑剂相对分子质量和分子结构、环境温度、增塑剂含量、介质和时间。归纳总结了各种能有效抑制PVC中增塑剂抽出及迁移问题的解决办法及研究成果,主要为添加聚酯增塑剂、添加纳米粒子、使用离子液体、表面改性、表面交联、表面喷涂防护涂层等。     

Effects of polyisocyanate on properties and pot life of epoxy resin cross‐linked soybean meal‐based bioadhesive

In this study, polyisocyanate (pMDI) was introduced into epoxy resin modified soybean meal‐based bioadhesive to address the issue of low dry bond strength. Specifically, we investigated the effects of adding pMDI in terms of amount and storage time on dry bond strength, water resistance, and pot life of adhesive. Factors examined included shear strength, apparent viscosity, chemical reaction, crystallinity, and morphology of modified adhesives. Results indicated that the dry bond strength and water resistance of the resultant plywood was respectively improved 29.5% and 39.7% by adding 2% pMDI. In addition, the pot life of modified adhesive reached in 4 h. Results also shown that the cross‐linking reactions between epoxy group and carbonyl as well as isocyano and amino increased the cross‐linking density and formed a denser cross‐linking network structure of cured adhesive. The composite cross‐linked soybean meal‐based adhesive is environmental‐friendly and high‐performance, which will promote the industrial application of the soy protein‐based adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43362.     

Morphology development of EPDM/PP uncross‐linked/dynamically cross‐linked blends

Ethylene‐propylene‐diene‐terpolymer (EPDM) and polypropylene (PP)‐based uncross‐linked and dynamically cross‐linked blends were prepared both in an internal mixer and in a corotating twin‐screw extruder. The effects of composition, plasticization and mixing equipment on the morphology development and the final viscoelastic properties were studied. In the uncross‐linked blends, the plasticization resulted in a coarser morphology. Furthermore, it was shown that the majority of the plasticizer resided in the EPDM phase, enabling its deformation in the flow direction. In addition, the intensive mixing conditions inside the twin‐screw extruder resulted in a finer morphology. In the dynamically cross‐linked blends, the twin‐screw extrusion process resulted in a higher level of gel content with larger EPDM domains. The plasticization showed again a coarsening effect, resulting in interconnected cross‐linked EPDM domains. An interesting interfacial phenomenon was observed especially in the plasticized vulcanized blends where nanometer size occluded PP domains were stripped off and eroded into the EPDM phase. With the exception of the nonplasticized uncross‐linked blends, the viscoelastic properties of all other blending systems were found to be directly affected by the morphology, gel content (in the case of cross‐linked blends), and the presence of the plasticizer. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Plasticizer transfer from plasticized PVC into ethanol–water mixtures

The transfer of plasticizer from compression-molded sheets of plasticized poly(vinyl chloride) into ethanol–water mixtures was studied over the temperature range of 30–55°C. A simultaneous diffusion occurred for ethanol and water into polymer and for dioctylphthalate plasticizer from polymer into liquid. The concentration of ethanol transferred into the polymer was found to increase, rise to a maximum, and then decrease. Equations of diffusion in unsteady state were found to correlate well with experiments on plasticizer transfer, over the plasticizer concentration range of 25–50 wt %. Stirring, temperature, water concentration in ethanolic solutions, and plasticizer concentration were found to play important roles.     

Genipin‐cross‐linked chitosan‐based hydrogels: Reaction kinetics and structure‐related characteristics

The main aim of this work is the synthesis and characterization of cross‐linked chitosan systems. Chitosan hydrogels can be prepared by physical or chemical cross‐linking of polymer chains. Chemical cross‐linking, leading to the creation of hydrogel networks possessing improved mechanical properties and chemical stability, can be achieved using either synthetic agents or natural‐based agents. In this work, the cross‐linker Genipin, a naturally derived compound, was selected because of the lower acute toxicity compared to many other commonly used synthetic cross‐linking reagents. In particular, the chemical stabilization of chitosan through genipin cross‐linking molecules was performed and characterized by calorimetric analyses (differential scanning calorimetry), swelling measurements in different pHs, and ionic strength. The reaction kinetics was carried out by means of rheological measurements, and both the activation energy (E_a) and the reaction order (m) were calculated. The hydrogel analyses were carried out at different concentrations of genipin (GN1 and GN2). The results were used to evaluate the possibility to use the chemical cross‐linked chitosan–genipin hydrogel for biomedical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42256.     

Microwave preparation and adsorption properties of EDTA‐modified cross‐linked chitosan

A novel chitosan‐based adsorbent (CCTE) was synthesized by the reaction between epichlorohydrin O‐cross‐linked chitosan and EDTA dianhydride under microwave irradiation (MW). The chemical structure of this new polymer was characterized by infrared spectra analysis, thermogravimetric analysis, and X‐ray diffraction analysis. The results were in agreement with the expectations. The static adsorption properties of the polymer for Pb²⁺, Cu²⁺, Cd²⁺, Ni²⁺, and Co²⁺ were investigated. Experimental results demonstrated that the CCTE had higher adsorption capacity for the same metal ion than the parent chitosan and cross‐linked chitosan. In particular, the adsorption capacities for Pb²⁺ and Cd²⁺ were 1.28 mmol/g and 1.29 mmol/g, respectively, in contrast to only 0.372 mmol/g for Pb²⁺ and 0.503 mmol/g for Cd²⁺ on chitosan. Kinetic experiments indicated that the adsorption of CCTE for the above metal ions achieved the equilibrium within 4 h. The desorption efficiencies of the metal ions on CCTE were over 93%. Therefore, CCTE is an effective adsorbent for the removal and recovery of heavy metal ions from industrial waste solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of color on expectations of drug effects: A cross‐gender cross‐cultural study

To study the role of color in expectations of drug effects, 80 Chinese participants (40 females and 40 males) were asked to classify each of seven single colored capsules and six differently colored two‐piece capsules into one of four classifications of drug effects. The results from the Chinese sample were also compared with that from four other cultural groups studied elsewhere. The Chi‐square test results showed that all seven single colored capsules yielded non‐chance distributions in classifications of drug effects, with six showing specific effects; and that five two‐colored capsules had non‐chance distributions, with four significantly associated with specific effects. Notable gender differences were observed in the expectations of drug effects. While the cross‐group comparison revealed consistent red‐stimulant and blue‐depressant associations across the five cultural groups, disagreements existed for other colors among the groups. The findings emphasized the importance of color in drug design and administration in support of drug differentiation, medication adherence, and drug efficacy, and suggest gender and cultural implications on the basis of color to achieve better drug effects. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 124–130, 2017     

Acetamide‐modified hyper‐cross‐linked resin: Synthesis,characterization, and adsorption performance to phenol from aqueous solution

Acetamide‐modified hyper‐cross‐linked resin, HCP‐HMTA‐AA, was prepared and its adsorption performance was evaluated using phenol as the adsorbate. The prepared HCP–HMTA–AA owned predominant micro/mesopores and medium polarity, making it possess a superior adsorption to phenol as compared with polystyrene (PS), chloromethylated polystyrene (CMPS), hyper‐cross‐linked polymer (HCP) and amino‐modified hyper‐cross‐linked resin (HCP–HMTA). The adsorption enthalpy was ?99.56 kJ/mol at zero fractional loading, multiple hydrogen bonding contributed to such a great adsorption enthalpy and an approximately planar hexahydric ring was formed between acetamide of HCP–HMTA–AA and phenol. The dynamic capacity of phenol on HCP–HMTA–AA was 291.3 mg/g at a feed concentration of 946.2 mg/L and a flow rate of 48 mL/h and the resin column was almost regenerated by a mixed solvent including 50% of ethanol (v/v) and 0.01 mol/L of sodium hydroxide (w/v). HCP–HMTA–AA was repeatedly used for five times and the equilibrium adsorption capacity for the five time reached 94.2% of the equilibrium adsorption capacity for the first time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41597.     

Synthesis and properties of cross‐linked polymers from epoxidized rubber seed oil and triethylenetetramine

A series of epoxidized oils were prepared from rubber seed, soybean, jatropha, palm, and coconut oils. The epoxy content varied from 0.03 to 7.4 wt %, in accordance with the degree of unsaturation of the oils (lowest for coconut, highest for rubber seed oil). Bulk polymerization/curing of the epoxidized oils with triethylenetetramine (in the absence of a catalyst) was carried out in a batch setup (1 : 1 molar ratio of epoxide to primary amine groups, 100°C, 100 rpm, 30 min) followed by casting of the mixture in a steel mold (180°C, 200 bar, 21 h) and this resulted in cross‐linked resins. The effect of relevant pressing conditions such as time, temperature, pressure, and molar ratio of the epoxide and primary amine groups was investigated and modeled using multivariable nonlinear regression. Good agreement between experimental data and model were obtained. The rubber seed oil‐derived polymer has a T_g of 11.1°C, a tensile strength of 1.72 MPa, and strain at break of 182%. These values are slightly higher than for commercial epoxidized soybean oil (T_g of 6.9°C, tensile strength of 1.11 MPa, and strain at break of 145.7%). However, the comparison highlights the potential for these novel resins to be used at industrial/commercial level. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42591.     

Kinetics and equilibrium of cobalt ion adsorption on cross‐linked polyethylenimine membrane

The kinetics and equilibrium of cobalt ion adsorption on crosslinked polyethylenimine (PEI) membrane were studied by the spectroscopic method in terms of time, cobalt ion concentration, and temperature. It was found that the adsorption of cobalt ion on crosslinked PEI membrane obeyed the pseudofirst‐order kinetic model and the equilibrium adsorption amount of cobalt ion on crosslinked PEI membrane was closely related to the initial cobalt ion concentration. The equilibrium adsorption amount increased with the decrease of temperature and obeyed a Langmuir isotherm to give the equilibrium constant for the adsorption of cobalt ion on crosslinked PEI membrane under various temperatures. Based on Van't Hoff equation the enthalpy and entropy of the adsorption of cobalt ion on crosslinked PEI membrane were determined to be ?12.9 kJ mol^?1 and ?107 J mol^?1 K^?1, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Electrospinning of highly aligned and covalently cross‐linked hydrogel microfibers

Smart polyelectrolyte hydrogels are increasingly studied toward the realization of soft microactuators. This study focuses on the fabrication of highly aligned and covalently cross‐linked polyacrylamide hydrogel microfibers by electrospinning technique following two‐stage polymerization. The engineering of the reaction timescale of the precursor, such that the material gels shortly after spinning, is described and the design of the electrospinning setup, to generate highly aligned fibers, is presented. In addition the effect of the operating parameters on the fibers average diameter is investigated. The generated fibers are 15 cm long with average diameter ranging between 100 nm and 1.10 μm. The fibers diameter is controlled by adjusting the thickener type and concentration in the precursor and the electrospinning processing parameters. Thinner fibers are generated at lower thickener molecular weights and concentrations as well at lower flow rate and higher voltage. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41092.     

Studies on structure property correlation of cross‐linked glycidyl azide polymer

Glycidyl azide polymer (GAP) has been evaluated for use as binder for solid propellants. The effects of various parameters like cross‐linking conditions, concentration of crosslinker, and the ratio of isocyanate to hydroxyl functional groups (NCO/OH ratio) on the mechanical properties were studied in detail. It was observed that the type of curing agent and the NCO/OH ratio have a strong influence on the gum‐stock properties. Similar impact was seen for cross‐linker concentration also. The swelling characteristics of the cross‐linked binder prepared with different NCO/OH ratios were evaluated with toluene and tetrahydrofuran (THF). The polarity and the solubility parameter of the solvents were found to influence the swelling of GAP. The NCO/OH ratio and cross‐linker concentration of the polymer were also found to affect the swelling characteristics. The sol fraction determined for the polymer was found to follow a similar pattern. The cross‐link density and average molecular weight between crosslinks (Mc) were determined from the swelling studies and also from the stress–strain relationship. The Mc values were found to be influenced by the NCO/OH ratio. Finally, the Mc values determined from the swelling data were correlated to the gum‐stock properties, and the model parameters were estimated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009