Industrial melt index prediction with the ensemble anti‐outlier just‐in‐time Gaussian process regression modeling method

Several data‐driven soft sensors have been applied for online quality prediction in polymerization processes. However, industrial data samples often follow a non‐Gaussian distribution and contain some outliers. Additionally, a single model is insufficient to capture all of the characteristics in multiple grades. In this study, the support vector clustering (SVC)‐based outlier detection method was first used to better handle the nonlinearity and non‐Gaussianity in data samples. Then, SVC was integrated into the just‐in‐time Gaussian process regression (JGPR) modeling method to enhance the prediction reliability. A similar data set with fewer outliers was constructed to build a more reliable local SVC–JGPR prediction model. Moreover, an ensemble strategy was proposed to combine several local SVC–JGPR models with the prediction uncertainty. Finally, the historical data set was updated repetitively in a reasonable way. The prediction results in the industrial polymerization process show the superiority of the proposed method in terms of prediction accuracy and reliability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41958.     

A novel Bayesian inference soft sensor for real‐time statistic learning modeling for industrial polypropylene melt index prediction

A novel real‐time soft sensor based on a sparse Bayesian probabilistic inference framework is proposed for the prediction of melt index in industrial polypropylene process. The Bayesian framework consists of a relevance vector machine for predicting melt index and a particle filtering algorithm for soft sensor optimization. An online correcting strategy is also developed for improving the performance of real‐time melt index prediction. The method takes advantages of the probabilistic inference and using prior statistical knowledge of polymerization process. Developed soft sensors are validated with ten public databases from UCI machine learning repository and real data from industrial polypropylene process. Experimental results indicate the effectiveness of proposed method and show the improvement in both prediction precision and generalization capability compared with the reported models in literatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45384.     

Synthesis and properties of novel fluorescent‐tagged polyacrylate‐based scale inhibitors

The two fluorescent monomers N ‐allyl‐4‐methoxy‐1,8‐naphtalimide ( F1 ) and N ‐allyl‐2‐(6‐hydroxy‐3‐oxo‐3H ‐xanthen‐9‐yl)benzamide (N ‐allylamidefluorescein, F2 ) have been synthesized and then conjugated to either polyacrylate (PAA) or to a co‐polymer of fumaric and acrylic acids (MA‐AA) to give four novel fluorescent‐tagged antiscalants: nonbiodegradable PAA‐F1, PAA‐F2 and biodegradable MA‐AA‐F1 , MA‐AA‐F2 . All four reagents demonstrate the fluorescence intensity suitable for inhibitors monitoring with a detection limit within 0.40 mg dm^?3. A good linear relationship between antiscalant fluorescent intensity and its dosage is detected. PAA‐F1, PAA‐F2, MA‐AA‐F1, and MA‐AA‐F2 can be used for corresponding scale inhibitor content on‐line measurement. For some antiscalants, the fluorescence is found to be dependent on the background heavy metal ions normally present in the cooling water. This effect is explained by the corresponding complexes formation. PAA‐F1, PAA‐F2, MA‐AA‐F1, and MA‐AA‐F2 revealed a good antiscaling activity toward CaCO₃ and CaSO₄ deposition, comparable with that one of commercial polyacrylates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45017.     

Preparation of block copolymers via metal‐free visible‐light‐induced ATRP for the detection of lead ions

Polyacrylamide‐b‐poly(methacrylic acid) was prepared on the surface of Au electrode (Au/PAM/PMAA) for Pb²⁺ ion electrochemical sensing via metal‐free visible‐light‐induced atom transfer radical polymerization, which was very simple, convenient, and environmentally friendly. Au/PAM/PMAA was carefully examined by cyclic voltammetry, electrochemical impedance spectroscopy, and X‐ray photoelectron spectroscopy. Further, Au/PAM/PMAA was successfully used for the determination of Pb²⁺ ion by differential pulse anodic stripping voltammetry. Under the optimal conditions, a linear response from 1.0 × 10^?11 to 1.0 × 10^?4 mol/L with detection limit of 2.5 × 10^?12 mol/L (S/N = 3) was achieved from the results of experiments. Comparing with similar Pb²⁺ sensors, the broader linear range and lower detection limit suggested the promising prospect of Au/PAM/PMAA. In a word, the work of this article had an important significance for the polymer‐modified electrodes and the sensitive detection of Pb²⁺. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45863.     

A biosensor platform based on amine functionalized conjugated benzenediamine-benzodithiophene polymer for testosterone analysis

A novel benzenediamine-benzodithiophene polymer is synthesized for use in biosensor fabrication for the detection of testosterone. The sensory platform is constructed via drop coating on a screen-printed carbon electrode, using poly(benzenediamine-Bis[(2-ethylhexyl)oxy]benzodithiophene) (pBDBT) as the polymer layer. Testosterone antibodies are immobilized on the polymer-coated electrode surface via glutaraldehyde, which binds to the surface through the amino functional groups on the polymer backbone. The changes in the surface features due to testosterone binding are investigated via electrochemical techniques such as differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectrometry as well as contact angle measurements. Surface morphology of the modified electrodes is characterized by atomic force microscopy. The linear range and limit of detection of the sensor are calculated. Impact of possible interfering compounds is investigated. Furthermore, the sensory platform is utilized for testosterone analysis in synthetic biological fluids.     

Ultraviolet–visible/fluorescence behaviors of a spiropyran/polydimethylsiloxane composite film under acid vapors

A spiropyran (SP)/polydimethylsiloxane (PDMS) composite film was prepared in this study, and its ultraviolet–visible/fluorescence behaviors under acid vapors were investigated. With UV irradiation, the ring‐closed SP in the PDMS matrix transformed to a ring‐opened merocyanine, which contained phenolate oxygen and could be further protonated by the hydrogen offered by the acid vapor. Such a protonation process endowed the composite film with not only an obvious color change from purple to yellow but also a strong fluorescent emission. As a result, some common volatile acids, hydrochloric acid, hydrofluoric acid, nitric acid, trifluoroacetic acid, formic acid, acetic acid, and propionic acid, could be distinguished with this method either via color or fluorescent emission. Meanwhile, the film showed good recyclability during the processes of irradiation and protonation. The method, therefore, displayed good processing in real time and was fast and recyclable; this makes it suitable as an alternative for applications related to environmental and safety monitoring of acid vapors. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45199.     

Electrospinning of poly(γ‐benzyl–α,L‐glutamate) microfibers for piezoelectric polymer applications

One of the latest developments in the field of piezoelectric polymers is the use of poly(γ‐benzyl‐α,L‐glutamate) (PBLG), a poly(amino acid) that can be poled along its α‐helical axis and fabricated into thermally stable piezoelectric microfibers via electrospinning. This study demonstrates a method for improving the piezoelectricity of electrospun PBLG microfibers by controlling the orientation of fibers using a method based on a concentrated electric field. The piezoelectricity is verified via customized quasi‐static and dynamic measurement methods, while the correlation between fiber alignment and the piezoelectric constant, d₃₃, in the longitudinal mode of the electrospun PBLG fibers is investigated. When the level of alignment was varied from 50% to 90%, the piezoelectric constant increased linearly, showing a maximum d₃₃ of 27 pC N^?1 and a maximum force sensitivity of 65 mV N^?1 at peak alignment. A fabricated flexible prototype based on electrospun PBLG fibers provides a new solution for the use of PBLG fibers in wearable energy harvesters or composites based on piezoelectric polymer fibers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46440.     

Wireless in‐mold melt front detection for injection molding: A long‐term evaluation

Wireless sensing technology for injection molding is of increasing interest in literature. Recently, a purely mechanical in‐mold sensor for melt front detection was introduced. The sensor system is based on building resonant structures into the mold which are excited by the passing melt front generating structure‐borne sound, from which the melt front position is derived. A big advantage of this system is the possibility to implement a plurality of resonant structures while just having one receiver. One important aspect is the need to separate and assign the recorded impinging sounds. A novel algebraic approach was introduced separating the resonant structures by reference to their oscillatory behavior. In this article, measurement results for over 450 injection molding cycles are given proving functionality of the separation process. In addition, it is shown that the melt front detection is reliable and robust when comparing it with results obtained by cavity temperature sensors. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40346.     

Real‐time property prediction for an industrial rubber‐mixing process with probabilistic ensemble Gaussian process regression models

In internal rubber‐mixing processes, data‐driven soft sensors have become increasingly important for providing online measurements for the Mooney viscosity information. Nevertheless, the prediction uncertainty of the model has rarely been explored. Additionally, traditional viscosity prediction models are based on single models and, thus, may not be appropriate for complex processes with multiple recipes and shifting operating conditions. To address both problems simultaneously, we propose a new ensemble Gaussian process regression (EGPR)‐based modeling method. First, several local Gaussian process regression (GPR) models were built with the training samples in each subclass. Then, the prediction uncertainty was adopted to evaluate the probabilistic relationship between the new test sample and several local GPR models. Moreover, the prediction value and the prediction variance was generated automatically with Bayesian inference. The prediction results in an industrial rubber‐mixing process show the superiority of EGPR in terms of prediction accuracy and reliability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41432.     

Chromatic detection of glucose using polymerization of diacetylene vesicle

A polydiacetylene vesicle was used to fabricate glucose sensor, allowing feasible colorimetric detection. The vesicle was formed by sonication of 10,12‐pentacosadiynoic acid (PCDA). H₂O₂ formed by the reaction between glucose and glucose oxidase functioned as the initiator for the polymerization of PCDA in the presence of horseradish peroxidase. The solution turned blue after the polymerization of PCDA vesicle. Thus, the glucose concentration could be detected to the concentration level that turns the solution to blue. The ultraviolet absorbance of glucose solution was proportional to glucose concentration. The results of this study indicate that glucose concentration upto 1 mM can be detected by change in blue color by eyes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46394.     

Tailoring copper (II) methacrylate‐containing copolymers and its use as electrode modifier agent in electroanalytical applications

This work focuses on the synthesis of a new class of copolymer materials consisting of traditional vinyl monomers (essentially, vinyl acetate, ethyl acrylate, and methyl methacrylate) and copper (II) methacrylate (Cu(II)MA) intended to be used as surface modification agents in electrochemical quantifications of organic and inorganic analytes. Voltammetry assays showed that when deposited on glassy‐carbon electrode (GCE), Cu(II)MA‐based copolymers are very promising materials to be applied in electrochemical determinations, exhibiting high analytical signal in the oxidation and reduction peaks during quantification of potassium hexacyanoferrate (III) in comparison to a bare GCE, contributing to increase the effective electrode area. When employed for the determination of ascorbic acid, PVAcCu(II)MA/GCE exhibited performance similar to that of the bare GCE. Polymers characterizations showed that glass transition temperature of the Cu(II)MA‐based materials increased in approximately 10–20°C, as consequence of the copper present in molecular structure of the copolymer chains (bidentate bridging coordination mode). Energy‐dispersive X‐ray spectroscopy measurements of Cu(II)MA monomer and Cu(II)MA‐based copolymers showed strong characteristic peaks Kα and Kβ at 8.04 and 8.90 keV, respectively, with an average amount of copper of 99%. The performance of the Cu(II)MA‐based copolymers modified electrodes is strongly dependent on the amount of copper into the copolymer chains and consequently on the monomers conversion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43202.     

Melt index prediction with a mixture of Gaussian process regression with embedded clustering and variable selections

In this study, a penalized mixture of the Gaussian process regression model was proposed for the prediction of melt index (MI) in industrial polymer production. MI plays an important role in detecting the grade of a product. It is difficult to measure directly and is characterized by a large number of variables and multigrades. Because of multigrade products, in the development of soft sensors for MI prediction, it is not valid to assume unimodal Gaussian distribution of the data. To this end, the proposed method is capable of the simultaneous identification of significant variables and determination of important clusters of multigrade products. It is based on the shrinkage methods that have been shown to provide stable models that are more interpretable. Case studies are presented to show the features of the proposed method and its applicability to industrial MI prediction. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45237.     

Mechanical and piezo‐resistive properties of styrene–butadiene–styrene copolymer covalently modified with graphene/styrene–butadiene–styrene composites

As novel piezoelectric materials, carbon‐reinforced polymer composites exhibit excellent piezoelectric properties and flexibility. In this study, we used a styrene–butadiene–styrene triblock copolymer covalently grafted with graphene (SBS‐g‐RGO) to prepare SBS‐g‐RGO/styrene–butadiene–styrene (SBS) composites to enhance the organic solubility of graphene sheets and its dispersion in composites. Once exfoliated from natural graphite, graphene oxide was chemically modified with 1,6‐hexanediamine to functionalize with amino groups (GO–NH₂), and this was followed by reduction with hydrazine [amine‐functionalized graphene oxide (RGO–NH₂)]. SBS‐g‐RGO was finally obtained by the reaction of RGO–NH₂ and maleic anhydride grafted SBS. After that, X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and other methods were applied to characterize SBS‐g‐RGO. The results indicate that the SBS molecules were grafted onto the graphene sheets by covalent bonds, and SBS‐g‐RGO was dispersed well. In addition, the mechanical and electrical conductivity properties of the SBS‐g‐RGO/SBS composites showed significant improvements because of the excellent interfacial interactions and homogeneous dispersion of SBS‐g‐RGO in SBS. Moreover, the composites exhibited remarkable piezo resistivity under vertical compression and great repeatability after 10 compression cycles; thus, the composites have the potential to be applied in sensor production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46568.     

A sensitive voltammetric sensor based on synergistic effect of graphene–polyaniline hybrid film for quantification of calcium antagonist lercanidipine

A chemically modified sensor based on the synergistic effect of graphene and polyaniline for electrochemical sensing of calcium antagonist lercanidipine (LCP) has been developed. Scanning electron microscopy, electrochemical impedance spectroscopy, square‐wave voltammetry, and cyclic voltammetry were utilized to characterize the morphology and electroanalytical performance of the fabricated sensor. Under optimized conditions, reduction peak current was linear over the wide concentration range from 5 to 125 ng mL^?1 with correlation coefficient of 0.9998. The limit of detection and the limit of quantification were found to be 1.94 and 5.89 ng mL^?1. The developed sensor also exhibited good reproducibility and long‐term stability. In addition, the proposed method was successfully applied to the determination of LCP in pharmaceutical formulation which is proved by recovery studies. Graphene–polyaniline composites are expected to be promising material for biosensing applications because of the ease of fabrication, excellent electrochemical performance, and high electroactive surface area. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40959.     

A novel water‐soluble polythiophene derivatives based fluorescence “turn‐on” method for protein determination

A lable‐free, simple, and sensitive fluorescence “turn‐on” approach is designed to rapidly detect protein using a conjugated polythiophene derivative (PDPMT‐Cl). The fluorescence of PDPMT‐Cl solution can be efficiently quenched by PtCl42? ions. Upon adding trypsin to the (bovine serum albumin, BSA) PDPMT‐Cl–PtCl42? solution, the BSA is cleaved into amino acid or peptide fragments, which are stronger PtCl42? ions chelators to form more stable complexes with PtCl42? ions. Thus, the PtCl42? ion is displaced from PDPMT‐Cl and the fluorescence of PDPMT‐Cl is recovered. By triggering the “turn‐on” signal of PDPMT‐Cl, it is successful to detect the protein in real time. “Turn‐on” response as readout signal is able to effectively reduce background noise and increase detection sensitivity. This method offers good selectivity for detecting protein in the presence of other common amino acids and metal ions. Under optimized conditions, the concentration of BSA in the range of 0.0004–1.75 mg/mL exhibits a linear relationship with the relative fluorescence intensity, and the correlation coefficient is 0.9997. The limit of detection is 4.47 × 10?4 mg/mL. The system is successfully applied for detecting protein in milk and egg. Due to the simplicity, sensitivity, and rapid response, this assay shows great potential for protein detection in the future. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 939‐943, 2013     

Chemical‐vapor‐sensitive materials based on a multiwalled carbon nanotube/hydroxyl propyl methylcellulose/cellulose composite

A type of chemical vapor‐sensing material made from multiwalled carbon nanotubes/hydroxyl propyl methyl cellulose/cellulose composite films were prepared in the room‐temperature ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([BMIm]Cl). A typical negative vapor coefficient was observed when the film was placed in polar organic solvents, such as methanol and ethanol. The sensitivity of the film to vapors increased significantly with increasing temperature. Interestingly, the resistance of the films increased almost linearly with decreasing vacuum, and the changes in resistance with the vacuum show good repeatability. The surface morphology, thermostability, and stress–strain properties of the composite films were analyzed with scanning electron microscopy, thermogravimetric analysis, and an electrical universal testing machine, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41639.     

Development of a pressure–volume–temperature measurement method for thermoplastic materials based on compression injection molding

The pressure–volume–temperature (pvT) relationship of polymers is vitally important information in designing and manufacturing polymers. Because of the special behavior of polymers, however, it is extremely difficult to accurately measure the data in a way that matches the thermal conditions of injection molding, which is one of the most widely used processing methods. As neither widely used, commercially available measuring devices, nor special equipment mentioned in the literature can fully satisfy this need, it was decided to build a new device able to determine the pvT relationship during injection molding of the polymer. The new device consists of a special mold that can be used on an injection molding machine and a data collection system connected to it. With the help of this device, pvT data can be measured during processing according to the thermal conditions of injection molding, and also considerably faster, and even in an industrial setting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41140.     

Low noise ultraviolet photodetector with over 100% enhanced lifetime based on polyfluorene copolymer and ZnO nanoparticles

Stability and noise current of a hybrid UV photodetector with inverted planar heterojunction (PHJ) structure indium‐tin‐oxide/ZnO nanoparticles (NPs)/poly[9,9′‐dioctyl‐fluorene‐2,7‐diyl]‐copoly[diphenyl‐p‐tolyl‐amine‐4,4′‐diyl] (BFE)/Ag are investigated. ZnO NPs as the acceptor and BFE as the donor were deposited as the active layer. Under UV light illumination, light to dark current ratio of about 10² is observed at a very low bias voltage of ?1.5 V. The spectral response of the device is located near UV region with a maximum responsivity of ～57 mA/W at wavelength of 350 nm. In particular, the prepared device exhibits remarkably higher photoresponse (～350%) and stability (～115%) enhancement under ambient condition compared to the reference device. In addition, the presented results show that the noise current of our device with PHJ structure is about an order of magnitude lower than that of commonly used bulk heterojunction system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46533.     

Polythiophene based fluorescent probe for copper ions with high sensitivity

Two new conjugated polymers poly{3‐({4‐[(2‐hydrazino‐2‐oxoethyl)(methyl)amino]cyclohexylidene}methyl)thiophene}( P1 ) and poly{3‐({4‐[(3‐hydrazino‐3‐oxopropyl)(methyl)amino]cyclohexylidene}methyl)thiophene}( P2 ) were synthesized, and their optical properties were investigated. P1 exhibited excellent selectivity toward Cu²⁺ ions in 50% water solution, the fluorescence color of P1 changed distinctly from greenyellow to colorless in the presence of Cu²⁺ under UV‐light, while introduction of other metal ions could not induce such significant variation. Moreover, highly sensitive detection of Cu²⁺ ions was demonstrated in 90% water solution. Its high metal‐chelating capability allowed Cu²⁺ recognition with a detection limit of 3.2 × 10^?10 M. These results indicated that this kind of nonionic polymer containing multidentate ligand could be used as a highly selective and sensitive chemosensor for Cu²⁺ detection. The proposed binding mode of P1 with Cu²⁺ was supported by DFT calculation using Gaussian 03. Unlike P1 , P2 showed no obvious fluorescent change in the presence of various metal ions due to its space steric hindrance resulted from N/O distribution on the side chain of P2 . © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42440.     

Sensing and surface morphological properties of a poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐bithiophene] liquid‐crystalline polymer for optoelectronic applications

The sensing properties of a poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐bithiophene] (F8T2) polymer were investigated at different concentrations and volume percentages. The effects of the concentrations and volume percentages on the sensing parameters were investigated. The sensitivities of F8T2 were found to be 3.190, 1.434, and 0.362 dB/vol % at 290, 580, and 940 nm, respectively. The response of the F8T2 increased with increasing concentration. F8T2 exhibited good sensitivity and response behaviors. Then, the optical parameters based on the refractive indices of the F8T2 at different molarities were calculated. The dispersion energy, moment of the dielectric constant optical spectrum (M_?1, M_?3), oscillator strength, and contrast of the F8T2 increased with increasing molarity, whereas the average excitation energy or single‐oscillator energy decreased with increasing molarity. The surface morphological properties of the F8T2 polymer film were investigated, and the roughness parameters were obtained. The F8T2 polymer could be used in the fabrication of various sensors because of the good solubility, sensitivity, and response behaviors. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41659.