Gas and water vapour transport in a polyketone terpolymer

Gas and water vapour transport properties of a polyketone terpolymer (0.93/0.07/1 ethylene/propylene/carbon monoxide) have been investigated and related to the polymer structure. Permeability tests have been performed at several temperatures (from 25 to about 65°C) with five different gases (oxygen, nitrogen, methane, ethane and carbon dioxide), evaluating permeabilities, diffusivities and solubilities. Their dependence on temperature was interpreted on the basis of apparent activation energies of permeation and diffusion (E_P and E_D) and of heats of solution (ΔH_S). The investigated polymer was found to be rubbery at the test temperatures (glass transition temperature is about 17°C), but the detected permeabilities are comparable to those of the glassy polymers widely used for packaging applications. Data obtained in this investigation on samples exposed to moulding temperatures (240°C) for 3 min were compared to gas permeation data (presented in a previous paper) obtained for samples exposed at that temperature for 33 min in order to assess possible effects on gas transport properties. Water vapour transport was analysed by performing both sorption (35, 34, 55 and 65°C) and permeation (35°C) experiments at several activities. The analysis of sorption isotherms revealed the occurrence of water clustering, which was confirmed by a reduction of water diffusivity as a function of water concentration in the polymer.     

Yield modeling of an aliphatic polyketone terpolymer in multiaxial stress states

A continuum yield model for pressure dependent anisotropic materials that accounts for the stress state has been combined with a thermally activated model to account for the temperature and rate dependence of yield stress. The resulting model has been applied to describe the yield behavior of a semicrystalline aliphatic polyketone terpolymer. Utilizing biaxial data from this thermoplastic, best‐fit values for loading along principal directions were determined. With these principal values, predictions for the yield strength under biaxial loading conditions were made. These predictions have been compared to experimental data obtained from the material at four different temperatures and three different strain rates. The experimental and theoretical results appear to compare quite well with each other.     

脂肪族聚酮技术进展

评述了脂肪族聚酮的最新进展，讨论了乙烯和CO共聚的钯催化体系、共聚机理和聚合工艺以及脂肪族聚酮的结构、性能和应用。     

Study of compatibility between aliphatic polyketone terpolymer and poly(styrene-r-acrylonitrile)

Compatibility studies have been conducted for polyketone (PK) and styrene–acrylonitrile (SAN) blends in which SAN polymers have different acrylonitrile (AN) contents. Measurements of mechanical properties exhibit the immiscibility of PK/SAN blends. Glass transition temperature shifts and width broadening of the glass transition mean partial compatibility in the amorphous region of the PK/SAN blends. Peak shifts of the CO functional group are larger for PK/SAN48 than that of PK/SAN40 blend. In morphological observations, the dispersed domains appear more refined for the PK/SAN48 blend and the PK/SAN48 blend has better boundary adhesion between the two phases. The Flory–Huggins interaction parameters simulated for the PK/SAN mixture were at a low level and the PK/SAN48 blend showed lower values than the PK/SAN40 blend. This means that the PK/SAN polymer blend is partially compatible in the amorphous region. The level of compatibility tends to increase as the AN content of the SAN polymer increases. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48743.     

Gas barrier changes and structural alterations induced by retorting in a high barrier aliphatic polyketone terpolymer

Analysis of the consequences of a typical humid thermal plastic food packaging sterilization (retorting) process over the crystalline morphology and gas barrier properties of a high barrier aliphatic polyketone terpolymer was carried out by in situ simultaneous synchrotron WAXS and SAXS experiments an by DSC, ATR‐FTIR spectroscopy, and oxygen transmission rate measurements. From a structural view point, it was observed that the retorting process led to a less crystalline material; however, crystallinity was fully restored by a postdrying process. The humid thermal treatment also favored the sorption of moisture in the amorphous phase to a saturation level, i.e., 2% water uptake. As a result, the oxygen permeability at 21°C was observed to increase by about nine times immediately after the humid treatment, but the barrier character was observed to quickly recover over time. From the results, it is suggested that a simple postdrying process at moderate temperatures can restore morphology and barrier properties. In the overall, it is also suggested that aliphatic polyketones withstand far better the process of retorting in comparison with, for instance, other high barrier polymers such as ethylene‐vinyl alcohol copolymers reported earlier and can therefore offer even as a monolayer an alternative in retortable food‐packaging applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3348–3356, 2006     

Influence of molecular weight on the fracture properties of aliphatic polyketone terpolymers

The influence of polymer molecular weight on the mechanical properties of aliphatic polyketones was investigated. The molecular weight varied from 100,000 to 300,000 g mol⁻¹. The crystallinity was found to be independent of polymer molecular weight, as was the glass transition temperature. The yield strength and stiffness of the aliphatic polyketone terpolymers were also found to be independent of molecular weight. The post yield behaviour showed strong dependency on polymer chain length. The draw stress was increased significantly with higher molecular weight material. The impact resistance was increased with molecular weight, resulting in ductile fractures with large energy consumption upon fracture. The brittle-to-ductile transition temperature was lowered with increasing chain length. The difference in material deformation was linked to the higher mechanical connectivity and more stable post yield behaviour of the polymers with an increased molecular weight.     

Effect of processing conditions on the structure and properties of polypropylene spunbond fabrics

The structure and properties of a spunbond fabric are determined by numerous process variables. The development of fiber morphology is influenced and controlled by extrusion and quenching conditions. The properties of the fabric are the result of the properties of the filaments, their arrangement in the web, and the bonding conditions. It is therefore critical to understand the relationship between the process conditions and the properties of the fabrics produced. This study was conducted to investigate the effects of some of the important process variables on the structure and properties of the filaments and ultimately on that of the fabrics. Process variables such as polymer throughput rate, cooling and suction air speed, web basis weight, and bonding temperature were investigated. Filament samples were collected before bonding and were analyzed for various properties such as crystallinity, crystallite size, birefringence, density, thermomechanical stability, and tensile properties. The fabric samples were analyzed for tensile properties, tear strength, stiffness, and crystallinity. Ruptured strips obtained from the tensile test were observed with a scanning electron microscope to understand the failure mechanism. The results were statistically analyzed to evaluate the effect of process variables on the properties and to predict the properties for different process conditions. The findings are helpful in determining the optimum processing conditions so as to achieve the desired properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2355–2364, 2005     

Effect of exfoliation and dispersion on the yield behavior of melt‐compounded polyethylene–montmorillonite nanocomposites

The yield behavior of melt‐mixed nanocomposites containing 5 wt % organically modified montmorillonite in matrices of a linear low‐density polyethylene (LLDPE) or a modified polyethylene was studied as a function of the temperature and strain rate. In the melt‐mixed LLDPE nanocomposite, the montmorillonite showed a slight increase in the clay spacing, which suggested that the clay was at best intercalated. Transmission electron microscopy (TEM) images showed that the dispersion in this nanocomposite was poor. The use of the modified polyethylene promoted exfoliation of the clay tactoids in the nanocomposite, as assessed by X‐ray diffraction and TEM. In both nanocomposites, the yield mechanisms were insensitive to the addition of the organoclay, even though modest increases in the modulus were produced. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3044–3049, 2006     

Synthesis of novel bipyridyl ligands and application in preparation of polyketone

In this article, novel 2,2′‐bipyridyl derivatives were synthesized and the excellent bipyridyl ligands were chosen as catalyst to apply in the copolymerization of carbon monoxide (CO) and styrene (ST) to prepare polyketone. 4,4′‐Dicarboxyl‐2,2′‐bipyridine(4,4′‐dcpy) was synthesized by use of synthesized 4,4′‐dimethyl‐2,2′‐bipyridine(4,4′‐dmpy). The products (4,4′‐dmpy and 4,4′‐dcpy) were characterized by melting point, NMR, IR, GC‐MS, and elemental analysis. The effects of different ligands and various reaction conditions incuding the usage of ligand, p‐toluenesulfonic acid, solvent, p‐benzoquinone, the CO pressure, and reaction temperature on catalytic activity of the copolymerization were investigated. The catalytic activity of 4,4′‐dmpy, 4,4′‐dcpy and 2,2′‐bipyridine were compared. The results showed that the addition of the electron‐donating substituent can enhance catalytic activity, with the sequence as follows: 4,4′‐ dimethyl‐2,2′‐bipyridine > 2,2′‐bipyridine > 4, 4′‐carboxy 2,2′‐ bipyridine. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2012     

Copolymerization of carbon monoxide with exo‐methylenecycloalkane and dienes: synthesis of functionalized aliphatic polyketones

Synthesis of functional aliphatic polyketones was achieved by co‐ and terpolymerization of the strained exo‐methylenecycloalkane, methylenecyclopropane (MCP), and also the dienes 1,5‐hexadiene, 1,7‐octadiene and 1,6‐heptadien‐4‐ol, with carbon monoxide and propene, using the dicationic palladium(II) phosphine complex [Pd(dppp) (NCCH₃)₂](BF₄)₂ (I) (dppp is 1,3‐bis(diphenyl‐phosphino)propane) as the catalyst precursor. The resulting MCP/CO copolymer contains both ring‐opened and cyclic microstructures. Ring‐opening copolymerization yields exo‐methylene functionalized polyketone. In contrast to hexadiene/carbon monoxide copolymer (Hx/CO), no ring structures were observed in the alternating octadiene/carbon monoxide (Oc/CO) and heptadien‐4‐ol/carbon monoxide (Hp‐ol/CO) copolymers. The remaining double bonds were left intact to yield polymers with olefinic functionalities in the side chains. © 2001 Society of Chemical Industry     

Effect of processing conditions on flash generation

Reduction of flash during injection molding is of great concern for manufacturers of electrical parts. In a previous report, we proposed a theoretical model for flash generation. The present study investigates the effect of processing conditions on flash generation and then attempts to analyze the flash data in terms of the flash model. Specifically, we carry out flow analyses to predict the temperature and pressure of materials when the flash generates. With the thus‐computed parameters, and material properties such as melt viscosity and crystallization temperature, a flash parameter defined in the model is calculated. In the end, it is shown that the flash parameter is correlated with the length of flash generated under various processing conditions. POLYM. ENG. SCI. 45:238–247, 2005. © 2005 Society of Plastics Engineers     

Thermodynamic theory of the viscoelasticity and yield of glassy polymers: Internal time theory

A nonlinear viscoelastic constitutive equation of glassy polymers has been developed on the basis of the internal time and irreversible thermodynamics of internal variables. The constitutive equation is a generalization of spring–dashpot models and describes the yield behavior of glassy polymers. With this constitutive equation, the rate of entropy production has been determined to show a peak near the yield. We propose a new yield criterion, that yield occurs at the maximum rate of entropy production. The yield criterion is almost equivalent to that of peak stress and a thermodynamic interpretation of yield. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2400–2411, 2003     

Effect of processing parameters on the surface resistivity of ethylene propylene diene terpolymer/multiwalled carbon nanotube nanocomposites

In this study, ethylene propylene diene terpolymer (EPDM) is melt‐mixed with multiwalled carbon nanotube (MWCNT). To realize full‐scale application of MWCNT to the rubber industries, the effect of melt‐processing parameters on the surface resistivity in the rubber/MWCNT nanocomposites should be well understood. The effect of rotor speed, mixing temperature, and annealing time on the surface resistivity of the EPDM/MWCNT nanocomposites has been investigated. The surface resistivity of EPDM/MWCNT nanocomposites with 3 phr MWCNT increases with increasing the rotor speed and decreasing the mixing temperature. Tensile strength and tensile modulus of EPDM/MWCNT (3 phr) nanocomposites are higher than those of EPDM, respectively. For the nanocomposite with 3 phr MWCNT loadings, surface resistivity increases as the annealing time at room temperature increases. This is the first report that surface resistivity of rubber/MWCNT nanocomposites increases significantly on annealing at room temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40129.     

Impact modification of aromatic/aliphatic polyamide blends: Effects of composition and processing conditions

Blends of aromatic/aliphatic polyamides of varying compositions were extrusion compounded with an impact modifying reactive elastomer and injection molded. The effect of two different twin-screw blending configurations on the physical and mechanical properties of the blends was evaluated. Effects of processing conditions on blend morphology were also examined. The experimental results indicate that the extrusion sequence affects the extent of polyamide matrix-elastomer reaction as well as the morphology. The relationship between blend morphology, blend components structure and reactivity, and processing conditions with ultimate properties is discussed. © 1996 John Wiley & Sons, Inc.     

Effect of processing conditions on the gloss of polypropylene films

A study of the effect of three processing variables, melt temperature, quench temperature, and air pressure, on the gloss of polypropylene films shows that although these processing parameters are used to control this property they do not constitute the primary cause of gloss variations. The main causes of gloss variations were found to be changes in the polymer melt index, i.e., melt roughness, and film crystallinity, both of which can be controlled by changing the processing conditions.     

Effect of cavitation on the plastic deformation and failure of isotactic polypropylene

To clarify the effect of cavitation, which is mostly induced by crystalline phase, on the plastic deformation and failure of isotactic polypropylene, solid‐state annealing at 160°C for 1.5 h is adopted to change the crystalline phase only while the amorphous phase keeps nearly intact. With aid of a special video setup, the relation of true stress and strain as well as the evolution of volume strain with axial strain has been derived. Enhancing crystalline phase due to annealing increases the yield stress and volume strain simultaneously. Moreover, the strain corresponding to steep increasing of volume strain is comparable with that related to yield, indicating that cavitation at early stage is accompanied with process of yield. With knowledge of toughness derived from impact tensile stretching and essential work of fracture (EWF), respectively, the relationship between cavitation and toughness has been correlated to some degree. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Study of the coagulated structure and fiber strength with wet spinning of aliphatic polyketone with aqueous composite metal salt solutions

Poly(1‐oxotrimethylene) (ECO) was dissolved in aqueous calcium chloride (CaCl₂)/zinc chloride (ZnCl₂) composite metal salt solutions, and the solutions had phase‐separation temperatures greater than 0°C. A higher proportion of CaCl₂ with respect to ZnCl₂ increased the phase‐separation temperature of the ECO solutions. When wet spinning was carried out with a coagulation bath at 2°C, an ECO solution with a higher phase‐separation temperature tended to produce greater ECO fiber strength. Therefore, a higher phase‐separation temperature resulted in coagulated filaments with a denser and more homogeneous cross‐sectional structure. When the metal salt concentration of the coagulation bath was increased with an ECO solution with a phase‐separation temperature of 22°C and a coagulation‐bath temperature of 2°C, the strength of the ECO fibers tended to be lower. Although little difference was observed in the uniformity of the fiber cross sections, a higher metal salt concentration in the coagulation bath facilitated greater spherical growth of the coagulated particles. Large, spherical coagulated particles promoted defects during drawing and thus lowered the strength of the ECO fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1250–1258, 2005     

Effect of thermal treatments on the yielding of polycarbonate

Two different thermal treatments were applied to polycarbonate (PC) in terms of slow cooling (annealed samples) after a thermal treatment at a temperature above the glass‐transition temperature or abrupt cooling in a liquid‐nitrogen environment (quenched samples). Tensile and compression experiments were performed on the two types of samples at three different effective strain rates. A viscoplastic model based on the fundamental assumptions of the Eyring model and on a kinematic formulation, which separated the viscoelastic and plastic strain, developed in previous works, was used to describe the yield and postyield behavior of thermally treated PC. The different thermal treatments affected the parameters of the material microstructure. A satisfactory agreement between the experimental data and calculated results was found. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 796–805, 2005     

抗静电硫化胶的加工条件对其导电性的影响

该文讨论了硫化体系，硫化模具温度和胶料的加工工艺对导电橡胶电性能的影响。