Effect of ethylene ionomers on the properties of crosslinked polyethylene

Most premature failure of underground crosslinked polyethylene (XLPE) cables in service, a matter of great concern, is due to aging induced by water treeing. To improve the water‐tree resistance, sodium‐neutralized poly (ethylene‐co‐acrylic acid) (EAA–Na) ionomers were blended with XLPE; the EAA–Na ionomers were prepared through the neutralization of sodium hydroxide and poly(ethylene‐co‐acrylic acid). A series of XLPE/EAA–Na ionomer blends were investigated through the measurement of the water absorption ratio, water treeing, and mechanical and dielectric testing; the results strongly suggested that EAA–Na ionomers could improve the water‐tree resistance of XLPE, and the XLPE/EAA–Na blends retained excellent mechanical properties and dielectric properties. Moreover, through the characterization of XLPE/EAA–Na blends with Fourier transform infrared spectrometry, dynamic mechanical analysis, and scanning electron microscopy, it was found that the neutralization reaction could be achieved completely; the XLPE and EAA–Na ionomers were partially compatible, so the EAA–Na ionomers could be dispersed well in the matrix with the process examined in this study. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3483–3490, 2007     

Mechanical properties of blends of HDPE and recycled urea‐formaldehyde resin

The mechanical properties of blends of high‐density polyethylene (HDPE) with a recycled thermosetting filler, urea‐formaldehyde grit (UFG), were evaluated in the range of 0–23% of filler by volume. Ethylene‐acrylic acid (EAA) copolymers and an ionomer based on EAA were evaluated as compatibilizers. The observed tensile modulus of the ionomer‐treated blends was raised to three times the modulus of virgin polyethylene, whereas the modulus of the untreated blends reached double that of polyethylene. The ionomer‐treated blends also showed a higher tensile strength than the blends without filler treatment. The improvement in the properties was assigned to an increased interaction between the filler and the polymer matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3220–3227, 2000     

Morphology,rheological and mechanical properties of poly(phenylene ether) and polyamide-6 blends with a compatibilizer

Summary The compatibilizing effect of styrene-acrylic acid random copolymers (SAA) on the morphology, rheological and mechanical properties of poly(phenylene ether) (PPE) and polyamide-6 (PA6) blends was investigated. By addition of a small amount (ca. 3wt%) of SAA copolymer, the blends show non-Newtonian power-law behavior at low frequency and the contribution of the storage modulus (G) to the total response increases. The blends containing SAA copolymer having acrylic acid content higher than 36mol% show more regular and finer dispersion and exhibit about 10% increased mechanical properties. It is believed from Molau test and MFI data that these results seem to attribute to the branch formation and MWD broadening by chemical reaction between terminal amine groups of PA6 and carboxyl groups of SAA.     

The effect of hydrogen bonding on the phase behavior of poly(ethylene-co-acrylic acid)-ethylene-cosolvent mixtures at high pressures

Experimental cloud-point data to 260 °C and 2,500 bar are reported to demonstrate the impact of two cosolvents, acetone and methanol, on the phase behavior of polyethylene, poly(ethylene-co-2.4 mol% acrylic acid) (EAA_2.4), poly(ethylene-co-3.9 mol% acrylic acid) (EAA_3.9), poly(ethylene-co-6.9 mol% acrylic acid) (EAA_6.9), and poly(ethylene-co-9.2 mol% acrylic acid) (EAA_9.2) in ethylene. In pressure-temperature (P-T) space, the miscibility of EAA copolymers in ethylene decreases significantly with temperature and with increasing acrylic acid content of EAA due to self-association of the acrylic acid segments. Acetone and methanol, both dramatically enlarge the solubility of EAA copolymers due to the hydrogen bonding with acrylic acids in the EAA. At low concentrations, methanol is a better cosolvent than acetone. However, the impact of methanol diminishes rapidly with increasing methanol concentration once all the acrylic acids in the EAA are hydrogen bond with methanol molecules.     

从聚苯乙烯大单体—丙烯酸丁酯—丙烯酸三元共聚物中和制得的热塑性弹性体的力学性能

研究了经离子中和的聚苯乙烯大单体与丙烯酸及丙烯酸丁酯共聚物的力学性能,包括中和方法、羧酸含量、中和度、金属离子种类及聚苯乙烯支链的含量及分子量等对力学性能的影响。这种双重物理交联产物的强度为未中和的三元共聚物或经离子中和的丙烯酸—丙烯酸丁醋共聚物的二倍。动态力学谱表明有二个玻璃化温度,呈现微观相分离。     

Effects of Dynamic Vulcanization and Acrylic Acid on Properties of Recycled Poly(vinyl chloride)/Acrylonitrile Butadiene Rubber (PVCr/NBR) Blends

Effects of dynamic vulcanization and acrylic acid (AAc) on processability, mechanical properties, swelling behavior, morphology, and thermal stability of recycled poly(vinyl chloride)/acrylonitrile butadiene rubber (PVCr/NBR) blends were investigated. Blends were prepared in a Haake Rheomix at a temperature of 150°C and a rotor speed of 50 rpm. Recycled poly(vinyl chloride)/acrylonitrile butadiene rubber (PVCr/NBR) blends were also prepared as comparison. It was found that the dynamic vulcanization and the addition of acrylic acid improved the stabilization torque, mechanical energy, stress at peak, stress at 100% elongation (M₁₀₀), swelling resistance, and thermal stability but decreased the elongation at break of the blends. The introduction of a cross-link into the elastomer phase and better compatibility between PVCr and NBR are responsible for the enhancement of thermal stability and mechanical properties of dynamically vulcanized PVCr/NBR + AAc as evidence from the scanning electron microscopy (SEM) of the tensile fracture surfaces and infrared spectroscopy study of the dynamically vulcanized of PVCr/NBR + AAc shows.     

Miscibility of poly(vinyl acetate) and vinyl acetate-ethylene copolymers with styrene-acrylic acid and acrylate-acrylic acid copolymers

Poly(vinyl acetate) and vinyl acetate-ethylene (VAE) copolymers compose one of the more important polymeric materials, widely employed in coating and adhesive applications. A new class of miscible polymer blends involving poly(vinyl acetate) and VAE with styrene-acrylic acid and acrylate-acrylic acid copolymers has been found. Experimental windows of miscibility as a function of the ethylene content for VAE copolymers and the acrylic acid content of the acrylate-acrylic acid copolymers are observed (acrylate = methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate). Employing well-established analog heat of mixing measurements, predicted windows of miscibility were compared with experimental results. Fair qualitative agreement was observed and supported the hypothesis that specific rejection arguments can be employed to explain the observed miscibility. Failure to quantitatively predict miscibility based on the analog heat of mixing measurements may be due to the higher association tendencies of the model compounds relative to acrylic acid units in the high molecular weight polymers. No miscible combinations were found for methyl methacrylate-acrylic acid copolymers or acrylate-methacrylic acid copolymers in admixture with poly(vinyl acetate) or the VAE copolymers, thus indicating the sensitivity of phase behavior to minor structural changes. VAE (30 wt % ethylene) copolymers were also noted to be miscible with several polymers previously noted to be miscible with poly(vinyl acetate), namely, poly(vinylidene fluoride), poly(ethylene oxide), and nitrocellulose. © 1995 John Wiley & Sons, Inc.     

聚氯乙烯／聚丙烯酸共混体系增容剂的合成及性能研究

利用聚氯乙烯的化学反应制备了丙烯酸代聚氯乙烯,用此与丙烯酸共聚,合成了聚氯乙烯接枝聚丙烯酸接枝共聚物;利用红外光谱仪表征了它们的化学结构,用此接枝共聚物作为ＰＶＣ／ＰＡＡ供混体系的增容剂;利用ＤＳＣ等实验方法研究了ＰＶＣ／ＰＡＡ增容体系的热性能及力学性能。实验结果表明,所合成的接枝共聚物能够显著提高聚氯乙烯与聚丙烯酸的相容性,当接枝率为０．５７时,增容效果最佳。     

增容剂EAA对PA6／POE共混体系的相态及性能的影响

采用乙烯－丙烯酸共聚物（EAA）作为尼龙6／乙烯－1－辛烯共聚物弹性体（POE）共混体系的增容剂,详细研究了增容剂用量与共混体系的相态、力学性能和流变性能的关系。结果表明相容剂的加入使共混体系的分散性大大改善,分散相POE粒子明显细化,粒子较均匀地分散在PA6连续相中;相容剂的加入使体系韧性明显提高,拉伸强度和弯曲弹性模量下降,加工性能也得到改善,而且当每100份PA6／POE用量为85／15、EAA用量在4月份左右时,其增容作用达到饱和,综合性能达到最优。     

Dynamic–Mechanical Properties of Bioartificial Polymeric Materials

Bioartificial polymeric materials represent a new class of polymeric materials based on blends of synthetic and natural polymers, designed with the purpose of producing new materials with enhanced properties with respect to the single components. The mechanical properties of bioartificial materials prepared using poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as synthetic components, and collagen (SC), gelatin, starch, hyaluronic acid (HA) and dextran as biological components, were investigated by dynamic mechanical thermal analysis. The materials were prepared in the form of films or hydrogels and treated by glutaraldehyde (GTA) vapour or thermal dehydration in order to reduce their solubility in water. The results indicate that SC/PVA, gelatin/PVA and starch/PVA films behave as biphasic systems, showing good mechanical properties over a wide range of temperature. It was observed that the GTA procedure affects only the biological component of the SC/PVA and gelatin/PVA blends, whilst the thermal treatment influences mainly the synthetic polymer. In the case of HA/PVA hydrogels, a modulus variation was found with the HA content related to the organization degree and perfection of the PVA network structure. It seems evident that, in the experimental conditions used, dextran/PAA mixtures behave as miscible blends showing a glass transition intermediate between those of the pure components. With both untreated and GTA-treated gelatin/PMAA blends, it was not possible to evaluate the miscibility of the systems; it could only be affirmed that these materials show good mechanical properties over a wide range of temperature. © 1997 SCI.     

Physicochemical characterization of hydrogels based on polyvinyl alcohol–vinyl acetate blends

Hydrogels made of polyvinyl alcohol–vinyl acetate and its blends with water soluble polymer were studied in terms of swelling behavior, microstructure, and dynamic mechanical properties. Hydrogels prepared by blending polyvinyl alcohol–vinyl acetate with either polyacrylic acid or poly(4‐vinyl pyridine) exhibited a strong pH dependency. When poly(vinyl pyrrolidone) was used for blending, an unusual pH dependency was observed. An increase in the equilibrium water content in all systems resulted in an increase in the freezable water as determined by DSC. Critical point drying led to a striated surface on polyacrylic acid–polyvinyl alcohol–vinyl acetate hydrogels, whereas a porous structure was observed on the freeze‐dried poly(vinyl pyrrolidone)–polyvinyl alcohol–vinyl acetate gels. Hydrogels with elevated storage modulus were obtained when either polyvinyl alcohol–vinyl acetate alone or polyacrylic acid–polyvinyl alcohol–vinyl acetate blends were thermally treated at high temperatures (i.e., 150°C). Low storage modulus was observed for both poly(vinyl pyrrolidone) and poly(4‐vinyl pyridine)‐containing hydrogels. Temperature dependency of storage modulus from 20 to 60°C was observed only for poly(4‐vinyl pyridine)–polyvinyl alcohol–vinyl acetate hydrogels. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3578–3590, 2001     

Studies on miscibility of blends of poly (ethylene acrylic acid) and ethylene‐co‐vinyl acetate by melt rheology

Rheological behavior of blends of poly (ethylene‐acrylic acid) (EAA) and ethylene vinyl acetate (EVA) copolymer have been carried out at various temperatures, namely, 100, 110, and 120°C, and different shear rates from 61.33 to 613.30 s^?1 using a Monsanto Processability Tester. The melt viscosity of the blends shows synergism during processing. The activation energy of the blends is in the range 20.7–44.6 kJ/mol. Highest activation energy was observed for the blends containing 40–60% of EVA by weight. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1947–1954, 2005     

Morphology,mechanical, and rheological properties of poly(lactic acid)/ethylene acrylic acid copolymer blends processing via vane extruder

This work aimed to study, for the first time, the melt blending of poly(lactic acid) (PLA) and ethylene acrylic acid (EAA) copolymer by a novel vane extruder to toughen PLA. The phase morphologies, mechanical, and rheological properties of the PLA/EAA blends of three weight ratios (90/10, 80/20, and 70/30) were investigated. The results showed that the addition of EAA improves the toughness of PLA at the expense of the tensile strength to a certain degree and leads the transition from brittle fracture of PLA into ductile fracture. The 80/20 (w/w) PLA/EAA blend presents the maximum elongation at break (13.93%) and impact strength (3.18 kJ/m²), which is 2.2 and 1.2 times as large as those of PLA, respectively. The 90/10 and 80/20 PLA/EAA blends exhibit droplet‐matrix morphologies with number average radii of 0.30–0.73 μm, whereas the 70/30 PLA/EAA blend presents an elongated co‐continuous structure with large radius (2.61 μm) of EAA phase and there exists PLA droplets in EAA phase. These three blends with different phase morphologies display different characteristic linear viscoelastic properties in the low frequency region, which were investigated in terms of their complex viscosity, storage modulus, loss tangent, and Cole‐Cole plots. Specially, the 80/20 PLA/EAA blend presents two circular arcs on its Cole‐Cole plot. So, the longest relaxation time of the 80/20 blend was obtained from its complex viscosity imaginary part plot, and the interfacial tension between PLA and EAA, which is 4.4 mN/m, was calculated using the Palierne model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40146.     

Storage modulus changes with temperature in poly(vinyl alcohol), PVA,/poly(acrylic acid), PAA, blends

Summary Poly(vinyl alcohol), PVA, and poly(acrylic acid), PAA, blends were prepared by solution casting. These polymers were found to be miscible in the whole composition range as determined by DSC even though some crystallinity remains in blends with PVA concentrations above 50wt%. Dynamic mechanical measurements of these blends and PAA as a function of temperature show an increase in storage modulus, E', when they reach a temperature of 140°C that is well beyond their softening point. The E' increase in PAA beyond 140°C is attributed to an intramolecular reaction of cyclic anhydride formation that stiffens the chain. Isothermal storage modulus test as a function of time and FTIR measurements at 160°C of PAA and three blends show that this increase in E' is due to cyclic anhydride formation. Received: 4 November 1998/Revised version: 11 March 1999/Accepted: 11 March 1999     

Mechanical properties–morphology relationships in nano‐/microstructured epoxy matrices modified with PEO–PPO–PEO block copolymers

Epoxy‐based blends containing poly(ethylene oxide)‐co‐poly(propylene oxide)‐co‐poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of the generated morphologies and interactions between components on the mechanical properties of the blends. Mechanical, morphological and dynamic mechanical analyses indicate that the observed increase of flexural modulus can be related to the decrease of free volume. In modified systems that remain miscible, an increase of flexural modulus, strength and fracture toughness can be observed. Also, macrophase‐ and microphase‐separated systems show an increase of fracture toughness but not of flexural modulus and strength at low contents of block copolymers. Copyright © 2007 Society of Chemical Industry     

r-PET/POE/EAA共混材料性能的研究

以回收聚对苯二甲酸乙二醇(酯r-PET)为基体材料,乙烯-辛烯共聚(物POE)为增韧材料,乙烯-丙烯酸共聚物(EAA)为相容剂,制备了r-PET/POE/EAA共混材料。用DSC、SEM分析了POE及EAA对r-PET结晶性能、断面结构的影响,并测试了共混材料的力学性能。结果表明:加入12%POE后,r-PET/POE共混材料的熔融温度降低了1.76℃,结晶度降低了16.49%,断裂伸长率及缺口冲击强度明显提高,弯曲强度和拉伸强度略有下降;在r-PET/POE共混材料中加入1.5%EAA后,POE球状粒子嵌入r-PET基体中,二者相容性提高,结晶速率加快;与纯r-PET相比,r-PET/POE/EAA共混材料的断裂伸长率和缺口冲击强度分别提高了698.01%和227.45%柔,韧性也大幅度提高。     

Polyblends. I. Mechanical properties of polyblends of butadiene–acrylonitrile elastomers and copolymers of vinyl stearate and vinyl chloride

Several nitrile rubber elastomers were polyblended, across the composition range, with selected polymeric compositions containing vinyl chloride. The compositions incorporated were (a) bulk poly(vinyl chloride) (PVC); (b) copolymers of vinyl stearate and vinyl chloride containing, respectively, 0.21, 0.36, and 0.47 weight fraction of the vinyl ester; and (c) mixtures containing the same weight fractions of di-2-ethylhexyl phthalate (DOP) with PVC. Mechanical, viscoelastic, optical, and volatility properties were studied on all blends in this first paper. To accurately compare the mechanical properties of polyblends of different systems, a criterion of mechanical equivalence was taken as the observance of similar stresses at break for compositions selected to have identical 100% moduli. Optimum mechanical equivalence, therefore, occurred at the largest ratios of 100% modulus to break stress for all systems compared. Optimum mechanical property equivalence was observed for NBR blends with PVC and for similar blends of both internally and externally plasticized systems containing 0.21 weight fraction of plasticizer. However, considerably more nitrile rubber was needed for PVC blends to acquire the properties of the plasticized systems. Mechanical equivalence was observed, but was not optimum for systems having more plasticizer because tensile strengths were lower. Polyblending with NBR improved the toughness and low-temperature properties of starting vinyl stearate copolymers. Improved toughness was indicated by the expansion of areas under stress–strain curves. Refractive index matching appeared to explain the transparency of the best films and their relative freedom from haze. On heating at 85°C, poly(vinyl chloride) and the copolymer polyblends suffered no volatility loss. Volatility of DOP from the blends was 1.5 times greater than for PVC–DOP mixtures. Because modulus–temperature curves and mechanical T_g values of the filler component shifted with composition, the mechanical behavior of these blends was in harmony with an accepted standard of interdomain compatibility.     

Interpolymer complexes of novel linear and crosslinked acrylic acid–Schiff base copolymers

Novel linear and crosslinked copolymers of acrylic acid and Schiff base, containing the amine groups in the main chain and the carboxylic groups in the side chain, have been synthesized by the Michael addition reaction followed by radical copolymerization. The copolymers that exhibited poly(ampholyte–electrolyte) behaviour were used to prepare complexes by reaction with anionic (poly(acrylic acid), poly(styrene sodium sulfonate)), cationic (polyethyleneimine, poly(hexamethylene guanidine)) and non‐ionic (poly(N‐vinylpyrrolidone), poly(ethylene glycol), poly(vinyl alcohol)) polymers. The influence of external factors, such as solvent quality, temperature, pH and ionic strength, on phase (coil–globule) and volume (swelling–collapse) transitions has been studied. © 2003 Society of Chemical Industry     

Injection moldability and properties of compatibilized PA6/LDPE blends

An ethylene‐acrylic acid copolymer (EAA), either alone or combined with a low molar mass bis‐oxazoline compound (PBO), has been used as a compatibilization promoter for blends of polyamide‐6 (PA6) with low‐density polyethylene (LDPE). The effect of compatibilization on blend processability in injection molding operations and on the properties of the molded specimens has been studied. In the absence of compatibilization, the injection molded articles were shown to have low‐quality surface appearance and poor mechanical properties. Both these characteristics were appreciably improved as a result of reactive compatibilization of the blends with EAA and, even more, with the EAA‐PBO couple. In fact, the finished articles prepared by injection molding of the quaternary blends were shown to possess good surface appearance, fine and stable morphology and satisfactory mechanical properties. The results confirm the conclusion of a previous study, i.e., that the PBO fourth component may promote the in situ formation of PA6‐g‐EAA copolymers, by reaction with both the functional groups of PA6 and the carboxyl groups of EAA. Polym. Eng. Sci. 44:1732–1737, 2004. © 2004 Society of Plastics Engineers.     

Synthesis of acrylate modified vinyl chloride and vinyl isobutyl ether copolymers and their properties

With acrylic acid, butyl acrylate and methyl methacrylate as the monomers, acrylate modified vinyl chloride and vinyl isobutyl ether copolymers were prepared by solution polymerization. Firstly, vinyl chloride and vinyl isobutyl ether copolymers were grafted with acrylic monomers to obtain a product containing acrylate grafted vinyl chloride and vinyl isobutyl ether copolymers and polyacrylate, which was then neutralized by triethylamine and dispersed into water to get a self-emulsified emulsion. The acrylate modified vinyl chloride and vinyl isobutyl ether copolymers were characterized by Fourier transform infrared spectroscopy. The mean molecular weight of grafted polymer was determined by gel permeation chromatography, and the particle sizes and their distributions of the dispersions were measured by laser light scattering. The influences of initiator concentration, acrylate content, acrylic acid content and neutralization degree upon the properties of the modified copolymers were discussed. The results show that the emulsion will be with good storage stability, and the modified polymer will be with high water resistance, impact resistance and excellent adhesion when initiator concentration is 1.5%, acrylate content is 50%, acrylic acid content ranges from 9% to 11%, and neutralization degree is between 80% and 100%.