Polymer Processing Technologies Research Articles

Meisenheimer Complex Inspired Catalyst- and Solvent-Free Synthesis of Noncyclic Poly(aryl ether sulfone)s

Identifying solvent- and catalyst-free conditions for polymerizations of engineering thermoplastics is of increasing interest due to new polymer processing technologies such as 3-D printing. We report the selective formation of linear poly(aryl ether sulfone)s (PESs) from the polycondensation of trimethylsilyl-protected bisphenol A (TMS-BPA) with nitro-substituted diaryl fluorides without added solvent or catalyst. DFT calculations show that nitro groups strategically placed in the ortho-position to the fluoride leaving group form a stable Meisenheimer complex during polyether synthesis. This strategy represents a route to linear PESs that employs anionic conditions, destabilizing propagating phenoxide chain ends preventing backbiting while simultaneously stabilizing the Meisenheimer complex intermediate. Thermodynamic over kinetic control in the polycondensation minimizes cyclic PES formation and promotes the formation of pure linear PESs.

Prediction of solubility of carbon dioxide in different polymers using support vector machine algorithm

This paper concerns with implementation of support vector machine algorithm for developing improved models capable of predicting the solubility of CO2 in five different polymers namely polystyrene (PS), poly vinyl acetate (PVAC), polypropylene (PP), poly butylene succinate-co-adipate (PBSA) and poly butylene succinate (PBS). Validity of the presented models has been evaluated by utilizing several statistical parameters. The predictions of the developed models for polymers of PS, PVAC, PP, PBSA, PBS are in excellent agreement with corresponding experimental data with the average absolute relative deviation percent (%AARD) equal to %0.151, %0.500, %1.381, %0.158, %0.239 and R2 values of greater than 0.999. Furthermore, the estimation capability of the proposed models has been compared to a well-known equation of state (EOS) as well as artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models. According to the results of comparative studies, it was found that the developed models are more robust, reliable and efficient than other existing techniques for improved analysis and design of polymer processing technology.

High Strength and High Modulus Electrospun Nanofibers

Electrospinning is a rapidly growing polymer processing technology as it provides a viable and simple method to create ultra-fine continuous fibers. This paper presents an in-depth review of the mechanical properties of electrospun fibers and particularly focuses on methodologies to generate high strength and high modulus nanofibers. As such, it aims to provide some guidance to future research activities in the area of high performance electrospun fibers.

Significantly Improving Oxygen Barrier Properties of Polylactide via Constructing Parallel-Aligned Shish-Kebab-Like Crystals with Well-Interlocked Boundaries

Recently, some attempts have been made to enhance the gas barrier properties of semicrystalline polymers by precisely controlling the arrangement of their impermeable crystalline lamellae. However, it is still a great challenge to achieve regular arrangement of the lamellae along the direction perpendicular to the gas diffusion path, especially using conventional polymer processing technologies. This work presents a novel and simple strategy to dramatically improve oxygen barrier performance of biobased and biodegradable polylactide (PLA) through constructing parallel-aligned shish-kebab-like crystals with well-interlocked boundaries with the aid of a highly active nucleating agent. The nucleating agent was introduced into PLA by melting compounding and the sheet-like specimens were fabricated by compression molding. We demonstrate that the fibrillar nucleating agent dispersed in PLA melt can serve as shish to induce the change of crystallization habit of PLA from isotopic spherulitic crystals to unique shish-kebab-like crystals and the shear flow in the compression molding can induce the highly ordered alignment of the nucleating agent fibrils as well as the subsequent shish-kebab-like crystals along the direction parallel to the sheet surface. More importantly, the growing lamellae are found to interpenetrate and tightly interlock with each other at the boundary regions of the shish-kebab-like crystals in the later stage of the crystallization, forming a densely packed nanobrick wall structure to prevent gas molecules from permeating through the crystals and thus imparting the PLA sheets with unprecedentedly low oxygen permeability. This work provides not only a successful example of preparing semicrystalline polymer with super gas barrier properties by tailoring crystal superstructure but also a promising route to rapidly fabricate high-performance food packaging materials via industrially meaningful melt processing.

Mechanics of Platelet-Reinforced Composites Assembled Using Mechanical and Magnetic Stimuli

Current fabrication technologies of structural composites based on the infiltration of fiber weaves with a polymeric resin offer good control over the orientation of long reinforcing fibers but remain too cumbersome and slow to enable cost-effective manufacturing. The development of processing routes that allow for fine control of the reinforcement orientation and that are also compatible with fast polymer processing technologies remains a major challenge. In this paper, we show that bulk platelet-reinforced composites with tailored reinforcement architectures and mechanical properties can be fabricated through the directed-assembly of inorganic platelets using combined magnetic and mechanical stimuli. The mechanical performance and fracture behavior of the resulting composites under compression and bending can be deliberately tuned by assembling the platelets into designed microstructures. By combining high alignment degree and volume fractions of reinforcement up to 27 vol %, we fabricated platelet-reinforced composites that can potentially be made with cost-effective polymer processing routes while still exhibiting properties that are comparable to those of state-of-the-art glass-fiber composites.

INVESTIGATION OF THE INFLUENCE OF MOLD ROTATIONAL SPEED ON THE CAST WALL THICKNESS IN THE ROTATIONAL MOLDING PROCESS

This paper presents the rotational molding process. The general principles of this polymer processing technology have been described. The main applications have been introduced and leading advantages and typical disadvantages of rotational molding process have been discussed. Based on the conducted experimental tests, the influ ence of changing one selected technological parameter, which characterized rotational molding process, on selected geometrical features of the polymer cast has been determined. Rotational mold’s speed around axes was changed and a thickness of cast walls has been measured. Laboratory test stand, processing properties of polymer, also test program and experimental test methodology have been described.

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate (TEC) was used as plasticizer. Melt strength decreases whereas melt extensibility increases with increasing plasticizer content. Melt strength was further studied as a function of zero shear viscosity. The typical draw resonance of the Rheotens curve shifts to higher drawdown velocity and the amplitude of the draw resonance decreases with increasing TEC content. With respect to foam extrusion, not only are melt strength and melt extensibility important but the elongational behavior at low strain rates and the area under the Rheotens curve are also significant. Therefore, elongational viscosity as well as specific energy input were calculated and investigated with respect to plasticizer content. Preliminary foam extrusion tests of externally plasticized CA using chemical blowing agents confirm the results from rheological characterization.

Conformal cooling channel design and CAE simulation for rapid blow mould

Blow moulding is one of the most important polymer processing technologies to produce hollow-shaped parts at a short time. The cooling stage takes up approximately two thirds of the complete blow moulding cycle. It becomes the major factor to determine the productivity and the quality of the blow-moulded part. The cooling time and the quality part are controlled by an adequate cooling channel design inside the blow mould. Inappropriate cooling channel design will increase the cooling time after part ejection. Recently, the success of integrating conformal cooling channel (CCC) design in the injection moulding process has been proven by different research publications and practices. The merit of the applications of CCC can also be extended to the existing blow moulding process. In this study, an effective design method is proposed for integrating CCC into the blow mould with the aid of computer-aided design and analysis tools. The fabrication of integrating CCC into the blow mould by rapid tooling technology is explored. Computer-aided engineering simulation is employed to verify the cooling performance of the CCC corresponding to the blow mould surface geometry. The analysed results are compared with those using the traditional straight line-drilled cooling channel (SLDCC) used in the blow moulding process. The results indicated that the cooling time and temperature uniformity of the blow-moulded part can be effectively improved. The proposed CCC design has a shorter cooling time and a lower part temperature than the SLDCC one.

A Concept of Differential-Integral Method Applied in Polymer Processing and Molding

In order to solve the bottleneck problem of polymer product processing striving for micro scale and precision or macro scale and complication in modern manufacturing, a concept of differential and integral method applied in advanced manufacture of polymer materials is brought up. On the base of this concept, principles of injection molding, extrusion, electrostatic spinning, nano-composite processing and structure innovation of polymer products have been studied; a series of new methods of polymer processing and molding, new equipments, and new technologies of product application have been invented. Some industrial application results prove that, the concept of differential and integral method applied in advanced manufacture of polymer materials is a valuable guide to break through the restriction of traditional manufacturing mode, and to develop new method of polymer processing and new technologies of polymer products application.

Raman Spectroscopy in Polymer Processing Technologies

Presented paper describes the application of Raman spectrometry in polymer processing technologies. Quick and reliable material identification is becoming and serrious issue in polymer processign technologies . Vibrational spectroscopy was long time used in polymer analysis. Preferred technique was the infrared spectroscopy (IR), but actual progress allows easy application of Raman spectroscopy and its main advantages. Raman spectroscopy detects vibrations that generate a change in the molecule's polarizability. The Raman effect arises when a photon is incident on a molecule and interacts with the electric dipole of the molecule. It is a form of electronic (more accurately, vibronic) spectroscopy, although the spectrum contains vibrational frequencies. Modern palm-sized Raman spectrometers allows simplified infield application. Quick online material identification on site is possible, or more specifical material characteristic is possible offline, when evaluating measured data with specialized software.

Research of Polymerization Reactor Fault Diagnosis Based on Acoustic Emission

With the development and improvement of polymer processing technology, safety production requires higher and higher levels of reactor fault diagnosis and assessment. In this paper, a new method is put forward for the polymer reactor on-line fault diagnosis basing on acoustic emission (AE). During the loading process of the reactor, sensors detect the AE signals. According to the acoustic emission and location theory, the fault or flaws of the reactor can be found and located. Further, the assessment of the reactor can be got and it can guide the safety production of the reactor.

In the expectation toward three dimensional evolution in polymer processing technology

In the expectation toward three dimensional evolution in polymer processing technology

Trend in Polymer Processing Technology of Europe

Trend in Polymer Processing Technology of Europe

The Role of Polymer Processing Technology to Progress the Sport Equipment

The Role of Polymer Processing Technology to Progress the Sport Equipment

Reduction of Carbon Dioxide and Polymer Processing Technologies

Reduction of Carbon Dioxide and Polymer Processing Technologies

Computer simulation of reactive extrusion processes for free radical polymerization

AbstractThe reactive extrusion for polymerization is an integrated polymer processing technology. A new semi‐implicit iterative algorithm was proposed to deal with the complicated relationships among the chemical reaction, the macromolecular structure and the chemorheological property. Then the numerical computation expressions of the average molecular weight, the monomer conversion, and the initiator concentration were deduced, and the computer simulation of the reactive extrusion process for free radical polymerization was carried out, on basis of which reactive processing conditions can be optimized. POLYM. ENG. SCI., 47:667–674, 2007. © 2007 Society of Plastics Engineers.

Numerical Solutions for Micropolar Transport Phenomena over a Nonlinear Stretching Sheet

We present a numerical study for the steady, coupled, hydrodynamic, heat and mass transfer of an incompressible micropolar fluid flowing over a nonlinear stretching sheet. The governing differential equations are partially decoupled using a similarly transformation and then solved by two numerical techniques – the finite element method and the finite difference method. The dimensionless translational velocity, microrotation (angular velocity), temperature and mass distribution function are computed for the different thermophysical parameters controlling the flow regime, viz the nonlinear (stretching) parameter, b, Grashof number, G and Schmidt number, Sc. All results are shown graphically. Additionally skin friction and Nusselt number, which provide an estimate of the surface shear stress and the rate of cooling of the surface, respectively, are also computed. Excellent agreement is obtained between both numerical methods. The dimensionless translational velocity (f′) for both micropolar and Newtonian fluids is shown to decrease with an increase in nonlinear parameter b. Dimensionless microrotation (angular velocity), g, generally increases with a rise in nonlinear parameter b (in particular in the vicinity of the wall) and decreases with a rise in convective parameter, G. The effects of other parameters on the flow variables are also discussed. The flow regime has significant applications in polymer processing technology and metallurgy.

Polymers and Supercritical CO 2 - An Invention to New Polymer Processing Technologies -

Polymers and Supercritical CO 2 - An Invention to New Polymer Processing Technologies -

Materials processing in supercritical carbon dioxide: surfactants, polymers and biomaterialsElectronic supplementary information (ESI) available: video clips relating to work carried out in the Howdle research group. See http://www.rsc.org/suppdata/jm/b3/b315262f/

Supercritical carbon dioxide (scCO2) is a unique solvent with a wide range of interesting properties. This review focuses upon recent advances in the use of scCO2 in materials synthesis and materials processing. In particular, we consider the advances made in three major areas. First the design and application of new surfactants for use in scCO2, which enable the production of metal nanoparticles, porous polymers and polymers of high molecular weight with excellent morphology. Second the development of new polymer processing and polymer blend technologies in scCO2, which enable the synthesis of some very complex polymer composites and blends. Finally, the application of scCO2 in the preparation of novel biomedical materials, for example biodegradable polymer particles and scaffolds. The examples described here highlight that scCO2 allows facile synthesis and processing of materials, leading to new products with properties that would otherwise be very difficult to achieve.

高圧力の可能性に挑む 高圧力流体による高分子材料の可塑化と加工

Subcritical and supercritical carbon dioxide (CO2), as an alternative solvent, is one of the unique fluids playing an important role in the development of environmentally favorable technologies. It acts as not only a good solvent to dissolve many low molecular substances, but also a good plasticizing agent for polymeric materials. Plasticization is the underlying principle in various polymer processing technologies with high-pressure CO2, such as low-temperature molding, polymer foaming, impregnation and surface modification. The purpose of this article is to review recent advances in polymer processing using CO2 fluid.