Fractionated crystallization of compatibilized LDPE/PA6 blends

The paper presents differential scanning calorimetry and electron microscopy of the fractionated crystallization and polydispersity of the dispersed PA6 phase in compatibilized LDPE/PA6 75/25 w/w blends. The compatibilizers used were (i) an acrylic acid functionalized polyethylene, Escor 5001 (EAA); (ii) an ethylene-glycidylmethacrylate copolymer, Lotader GMA AX8840 (EGMA); (iii) a polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer comprising 2 wt.% maleic anhydride grafts, Kraton FG 1901X (SEBS-g-MA). The compatibilizer SEBS-g-MA has the strongest reduction effect upon the size of PA-6 droplets. Its implementation provides the best fractionated crystallization. The fractionated crystallization has not been observed for the blend compatibilized with EGMA. The results show that the degree of compatibilization could be evaluated qualitatively by the progress of the fractionated crystallization. So, the three compatibilizers could be rated according to their effectiveness as follows: SEBS-g-MA > EAA > EGMA. The self-nucleation experiments have demonstrated that the lack of active nuclei in the finely dispersed PA6 droplets is the determining factor for the fractionated crystallization at high supercooling, and not the considered absolute particle size. The measurement of the Vickers microhardness of the compatibilized blends confirms that the compatibilizing activity of SEBS-g-MA and EAA is stronger than that of EGMA.     

Influence of compatibilization on the mechanical behavior of poly(trimethylene terephthalate)/poly(ethylene-octene) blends

Poly(trimethylene terephthalate) (PTT) based blends toughened with up to 30 wt.% of a partially maleinized poly(ethylene-octene) copolymer (mPEO) were obtained by melt mixing. The blends were composed of two pure amorphous phases and a partially crystalline PEO phase. The rubber modification clearly compatibilized the blends leading to a decrease in the dispersed phase size. The decrease was not enough to attain the brittle-tough transition, but an increase in the shear rate gave rise to an additional decrease in the dispersed phase size and in the interparticle distance (IDc) that led to very high toughness values (15-fold the notched impact strength of the matrix) at rubber contents above 25 wt.%. The critical interparticle distance of the blends was 0.17 μm. A comparison between this IDc and those of PBT/mPEO and PET/mPEO blends was explained in terms of their interfacial tensions.     

Preparation of flame retardant polyamide 6 composite with melamine cyanurate nanoparticles in situ formed in extrusion process

This paper is focused on in situ preparation of melamine cyanurate (MCA) nanoparticles from reaction of melamine (MEL) and cyanuric acid (CA) and their flame retardant polyamide 6 (PA6) composite in the extrusion process through a novel reactive processing method. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were utilized to characterize the in situ formed MCA nanoparticles and their blends with PA6. Introduction of pentaerythritol (LTP) and water-bound plasticizer dioctyl phthalate (DPT) into the extrusion reaction system greatly inhibits the evaporation of water required for melamine and cyanuric acid reaction at high temperature (higher than 180 °C), laying a foundation for successful in situ preparation of MCA through reactive processing. XRD and FT-IR measurements indicate that under the effect of pentaerythritol, dioctyl phthalate and water, melamine really reacts with cyanuric acid to in situ form MCA in extrusion process. The reaction degree is close to 100%. A very important finding through SEM is that the in situ formed MCA particles, which were found to have aspect ratio of about 7.5, radial size in the range of 70-300 nm (mostly 70-90 nm) and crystallite size of less than 22 nm, are uniformly dispersed in the matrix PA6 at nanoscale. The in situ formed MCA nanoparticles greatly improve the flame retardancy and the mechanical properties of flame-retarded PA6 materials, and the introduced plasticizer dioctyl phthalate also ameliorates the related impact property. The obtained flame-retarded PA6 materials have good comprehensive performance with flame retardancy UL-94 V-0 rating at 1.6 and 3.2 mm thickness, tensile strength 48.0 MPa, elongation at break 106.3% and Izod notched impact strength 8.92 kJ/m². Compared with flame-retarded PA6 material with in situ formed MCA, the one prepared through conventional blending of PA6 with commercial MCA product has improved tensile strength but deteriorated impact strength and flame retardancy.     

Photooxidative behaviour of polyethylene/polyamide-6 blends

The photochemical behaviour of several polyethylene/polyamide-6 blends was studied under conditions of artificial accelerated weathering. Particular attention was paid to five different compositions ranging from pure polyethylene to pure polyamide with blends of PE/PA-6 of various compositions: 75/25, 50/50 and 25/75 wt/wt%. Analysis by infrared spectroscopy of the chemical modifications caused by photooxidation showed that exposing the polyethylene/polyamide-6 blends to UV-light irradiation led to the formation of oxidation photoproducts in both polymer phases. In agreement with both the mechanical and spectroscopic analyses, the photooxidation rate of the blends was observed to be much higher than that of the homopolymers. The results given in this paper suggest that photooxidation of the PE/PA blends starts in the polyamide phase and that the subsequent photooxidation of the polyethylene phase may be initiated by the radicals coming from the oxidation of PA.     

壳-核结构增韧剂超高增韧非晶共聚酯的形貌和形态

研究了马来酸酐接枝的壳核结构增韧剂 (TPEg)对非晶热塑共聚酯 (PETG)的增韧和增强效果 ,并与马来酸酐接枝的纯橡胶类增韧剂 (POEg)作了对比 .TPEg对PETG具有显著的增韧效果 ,当TPEg含量由 5%增加到 1 0 %时 ,共混物就可以发生由脆性到超高韧性的快速转变 .而POEg虽然也可以使PETG发生由脆性到韧性的快速转变 ,但转变是在较高的增韧剂含量下发生的 ,这意味着共混物的抗张强度和模量损失更多 .利用扫描电镜观察、分析了随增韧剂含量的增加 ,共混物的形貌、形态的演化过程 .共混物的缺口冲击韧性与其形貌、形态之间存在很好的对应关系 .     

Effects of polybutadiene-g-SAN impact modifiers on the morphology and mechanical behaviors of ABS blends

A series of PB-g-SAN impact modifiers with different ratio of PB to SAN ranging from 20.6/79.4 to 91.9/8.1 were synthesized by seeded emulsion polymerization. ABS blends were prepared by blending these PB-g-SAN impact modifiers and SAN resin. The rubber concentration of these ABS blends was kept at a constant value of 15 wt%. The influences of different impact modifier on the mechanical behavior and morphology of ABS blends have been investigated. The dynamic mechanical analysis on ABS blends shows that T_g of the rubbery phase shifts to a lower temperature, (tan δ)_max of the rubbery phase increases and then decreases with the increase of PB concentration in PB-g-SAN impact modifier. A uniform dispersion of rubber particles in the matrix can be observed when PB/SAN ratio in PB-g-SAN impact modifier is in the range from 20.6/79.4 to 71.7/28.3. When it exceeds 71.7/28.3, an agglomeration of rubber particles occurs. The mechanical tests indicate that the ABS blend, in which PB/SAN ratio in the impact modifier is 71.7/28.3, has the maximum impact strength and yield strength.     

Thermal and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) plasticized by biodegradable soybean oils

The effects of soybean oil (SO) and epoxidized soybean oil(ESO) as biodegradable plasticizers for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were studied using thermal and mechanical analyses. PHBV/SO and PHBV/ESO blends were prepared by evaporating solvent from blend solutions. The levels of additive in the blend varied from 5% to 30%. As a plasticizer for PHBV, ESO was more effective than SO in depression of the glass transition temperature as well as in increasing the elongation at break and the impact strength of the films with increasing levels of additive. Biodegradation of the plasticized PHBV films was carried out by accelerated compost method. The degradation rates of the blend films with SO or ESO were found to be faster than that of PHBV film. From the thermogravimetric analysis, it was found that the thermal reaction between the epoxide groups of ESO and PHBV fragments with carboxylic chain ends, occurred during the degradation of PHBV/ESO blends.     

Studies on the blends of cardanol-based epoxidized novolac resin and CTPB

Cardanol-based novolac-type phenolic resins were synthesized with different mole ratios of cardanol-to-formaldehyde, viz., 1:0.6, 1:0.7, and 1:0.8. These novolac resins were epoxidized with molar excess of epichlorohydrin at 120 °C in basic medium. The epoxidized novolac resins were, separately, blended with different weight ratios of carboxyl-terminated polybutadiene liquid rubber ranging between 0-25 wt% with an interval of 5 wt%. All the blends were cured at 150 °C with 40 wt% polyamide. The formation of various products during the curing of blend samples has been studied by Fourier-transform infra-red spectroscopic analysis. The tensile strength and elongation-at-break of the cured samples increased up to 15 wt% in the blend and decreased thereafter. This blend sample was also found to be most thermally stable system. The blend morphology, studied by scanning electron microscopy analysis, was finally correlated with the structural and property changes in the blends.     

Analysis of thermomechanical reprocessing effects on polypropylene/ethylene octene copolymer blends

The impact of recycling by grinding and re-extrusion on the physical and mechanical properties of polypropylene (PP)/ethylene octene copolymer (EOC) blends was investigated. The considered EOC content was 0 wt. %, 10 wt. % and 20 wt. %, and the investigated number of recycling passes (extrusions) was 0, 1, 3 and 6. Up to 6 re-extrusions, an increase of the melt flow index (MFI), a slight increase of the crystallinity, a slight decrease of the decomposition temperature (T_onset), and no significant oxidation were noted. Therefore, the recycling of the blends induces thermomechanical degradation by chain scission without oxidation. Increasing the content of EOC increases the MFI and the T_onset of the PP blends. The first recycling procedure induced an increase of the Young's modulus and tensile yield stress, while for higher recycling numbers, these two parameters dropped. The EOC inclusions stabilized the tensile elongation at break up to 3 recycling procedures due to a decrease of their size and a homogenization of their shape, while that of neat PP continuously decreased with recycling numbers.     

Analyse de la relations structure-proprietes des melanges PVC-PMMA

Analysis of Structure-Properties Relationship of PVC-PMMA Blends. This paper presents a study of the structure-properties relationship of PVC-PMMA blends. For that purpose, blends of variable compositions from 0 to 100 wt % were prepared. Their physico-chemical characterization was carried out by differential scanning calorimetric analysis (DSC) and Fourier Transform Infrared spectroscopy (FTIR). The analysis of thermograms showed polymer miscibility up to 60 wt % PMMA. This miscibility is due to a specific interaction of hydrogen bonding type between carbonyl groups (C+O) of PMMA and hydrogen from (CHCl) groups of PVC. The two-band deconvolution showed an increase in associated groups percentage in the domain of miscibility. The variation of mechanical properties such as tensile behaviour, hardness and impact resistance was investigated for all blend compositions. The effect of a plasticizer on the same properties was considered. The obtained results show that a range of properties can be generated according to the blend compositions.     

RHEOLOGICAL BEHAVIOR OF POLYPHENYLENE SULFIDE/POLYAMIDE-66 BLENDS

Blends of polyphenylene sulfide (PPS) containing trace amounts of branching and/orcross-linking in chain and Polyamide-66(PA-66) have been prepared by melt blending. Therheological behavior of PPS/PA-66 blends has been studied by means of capillary rheo-meter, and compared with PPS. The effects of shear rate, shear stress and temperature onthe flow of PPS/PA-66 blends and PPS are discussed. The non-Newtonian indexes andthe activation energies of viscous flow are obtained. The results show that the apparentviscosity of PPS/PA-66 blends is not sensitive to shear rate and stress, but decreases withthe elevation of temperature. On the contrary, the apparent viscosity of the PPS decreasesobviously with the increasing of shear rate and shear stress, but it is increased by theelevation of temperatue.     

Photochemical aging of in situ polymerized blends of polystyrene and poly[acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene] (AES)

The influence of photochemical aging of in situ polymerized PS/AES blends on their mechanical properties has been studied. The PS/AES blends were subjected to photochemical aging for 168 h and 720 h. Tensile properties and Izod impact resistance of aged and non-aged samples were evaluated. The mechanical properties of the PS/AES blends are influenced by the polymerization temperature and blend composition and represent a balance between the toughness of EPDM and the stiffness of SAN in the PS matrix. Even though the impact resistance and strain at break of HIPS are higher than those of the PS/AES blends, after the aging period all PS/AES blends showed higher strain at break than HIPS. PS/AES blends present higher photochemical stability than HIPS.     

Nanostructure formation in polymer thin films influenced by humidity

The influence of relative humidity (RH) during the film preparation on the surface morphology and on the material distribution of the resulting technical polymer blend films consisting of poly (methyl methacrylate) (PMMA) and poly (vinyl butyral) (PVB) is investigated by atomic force microscopy. Both pure polymers and polymer blends with different compositions of PVB/PMMA dissolved in tetrahydrofuran (THF) were used. Polymer films prepared under dry conditions (RH < 20%) are compared with those that have the same polymer composition but were prepared under increased humidity conditions (RH > 80%). The films consisting of the pure polymers showed a nonporous surface morphology for low‐humidity preparation conditions, whereas high‐humidity preparation conditions lead to porous PVB and PMMA films, respectively. These pores are explained as the result of a breath figure formation. In the case of the polymer blend films containing both polymers, porous or phase‐separated surface structures were observed even at low‐humidity conditions. A superposition of the effects of phase separation and breath figure formation is observed in the case of polymer blend films prepared under high‐humidity conditions. Atomic force microscopy (AFM) images taken before and after the treatment with ethanol as a selective solvent for PVB indicate that PMMA is deposited on top of a PVB layer in the case of the low‐humidity preparation process whereas for high‐humidity conditions the silicon substrate is covered with a PMMA film. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of EVM/EVA‐g‐MAH ratio on the structure and properties of nylon 1010 blends

The nylon 1010/ethylene‐vinyl acetate rubber (EVM)/maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) ternary blends were prepared. The effect of EVM/EVA‐g‐MAH ratio on the toughness of blends was examined. A super tough nylon 1010 blends were obtained by the incorporation of both EVM and EVA‐g‐MAH. Impact essential work of fracture (EWF) model was used to characterize the fracture behavior of the blends. The nylon/EVM/EVA‐g‐MAH (80/15/5) blend had the highest total fracture energy at a given ligament length (5 mm) and the highest dissipative energy density among all the studied blends. Scanning electron microscopy images showed the EVM and EVA‐g‐MAH existed as spherical particles in nylon 1010 matrix and their size decreased gradually with increasing EVA‐g‐MAH content. Large plastic deformation was observed on the impact fracture surface of the nylon/EVM/EVA‐g‐MAH (80/15/5) blend and related to its high impact strength. Then with increasing EVA‐g‐MAH proportion, the matrix shear yielding of nylon/EVM/EVA‐g‐MAH blends became less obvious. EVM and EVA‐g‐MAH greatly increased the apparent viscosity of nylon 1010, especially at low shear rates. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 877–887, 2009     

Miscibility and interfacial property studies of the blends of ethyl cellulose with copolyamide6/66/1010

Interfacial properties governing reverse osmosis separations were studied by using liquid chromatography data with respect to ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends. The miscibility of ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends was investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared, while the interfacial properties of the blends, including the interfacial adsorption, hydrophobicity, polar and non-polar parameters and β-parameters, were studied by using liquid chromatography. The results show that EC and PA-130 are miscible at compositions of (80/20), (70/30) and (50/50). The hydrophobicity of EC/PA-130 increases with the of PA-130 content. The EC/PA-130(70/30) is superior to the other blends for separating non-dissociable polar organic solute and is more suitable for use as desalting membrane material. It seems that liquid chromatography is an effective tool for studying the interfacial properties of polymer blend materials and selecting high performance of membrane materials.     

Polymer blends of sPS/PA6 compatibilized by sulfonated syndiotactic polystyrene

Syndiotactic polystyrene (sPS) and polyamide-6 (PA6) are immiscible and incompatible and have been recognized. In this study, sulfonated syndiotactic polystyrene (SsPS-H) is employed as compatibilizer in the blend of sPS/PA6. During melt blending, the sulfonic acid groups of the SsPS-H can interact strongly with the amine end-groups of PA6 through acid-base interaction. In addition, SsPS-H is miscible with sPS when SsPS-H content is less than 20 wt.%. Therefore, the addition of SsPS-H to sPS/PA6 blends reduces the dispersed phase size and improves the adhesion between the phases. The glass transition temperatures of the PA6 component in the compatibilized blends shift progressively towards higher temperature with the content of SsPS-H-12 increase, indicating enhanced compatibility. On the other hand, the progressive lowering of the melting point and crystallization temperatures of PA6 in the blends with increasing SsPS-H contents compared to the incompatibilized blend, provide some insight into the level of interaction between the PA6 and SsPS-H. The compatibilized blends have significantly higher impact strength than the blends without SsPS-H. The best improvement in the impact strength of the blends was achieved with the content of the SsPS-H (11.9 mol%) about 5 wt.%.     

Effect of fillers on fire retardancy of intumescent polypropylene blends

Addition of Ammonium Polyphosphate/Polyamide-6 system is known to provide flame retardancy in many polymers blends via an intumescent process. Particulate fillers (talc and calcium carbonate) are used in large quantities in PP. Combination of fillers in PP can modify the properties of the polymeric matrix. This study investigates the effect of fillers (talc and calcium carbonate) on the fire performance of the Polypropylene/Ammonium polyphosphate/Polyamide-6 blend. It is shown that the fire performance strongly depends on the nature of the filler used. Talc increases and calcium carbonate decreases in the fire performance of the blend.     

New super‐tough poly(butylene terephthalate) materials based on compatibilized blends with metallocenic poly(ethylene‐octene) copolymer

New super‐tough poly(butylene terephthalate) (PBT)/poly(ethylene‐octene) copolymer (PEO) blends containing 2 wt% poly(ethylene‐co‐glycidyl methacrylate) (EGMA) as a compatibilizer were obtained by extrusion and injection molding. The blends comprised of an amorphous PBT‐rich phase with some miscibilized EGMA, a pure PEO amorphous phase, and a crystalline PBT phase that was not influenced by the presence of either PEO or EGMA. The blends showed a fine particle size up to 20 wt% PEO content. Super‐tough blends were obtained with PEO contents equal to or higher than 10%. The maximum toughness was very high (above 710 J/m) and was attained with 20% PEO without chemical modification of the commercial components used. Copyright © 2003 John Wiley & Sons, Ltd.     

Structure and properties of blend membranes prepared from cellulose and alginate in NaOH/urea aqueous solution

Regenerated cellulose (RC)/alginic acid (AL) blend membranes were satisfactorily prepared from 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl₂ aqueous solution, and then treated with 3 wt % HCl. Morphology, crystallinity, mechanical properties, and thermal stability of the membranes were investigated by scanning electron microscopy (SEM), IR and UV spectroscopes, X‐ray diffraction, tensile tests, and thermogravimetric analysis (TGA). The RC/AL blends were miscible in all weight ratios of cellulose to alginate. The membranes have homogeneous mesh structures, and the mesh sizes of the blend membranes (200–2000 nm) significantly increased with increasing alginate content. The crystalline state of the AL membrane prepared from 6 wt % NaOH/4 wt % urea aqueous solution was broken completely, and the crystallinity of the blend membranes decreased with an increase of AL. Comparing with AL membranes, the tensile strength and breaking elongation of the blend membranes were obviously improved in dry and wet states. Therefore, the RC/AL blends offer a promising way of alginate as separate and functional materials used in the wet state. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 451–458, 2001     

A new route to obtain PVDF/PANI conducting blends

Electrically conductive poly(vinylidene fluoride)(PVDF) - polyaniline blends of different composition were synthesized by chemical polymerization of aniline in a mixture of PVDF and dimethylformamide (DMF) and studied by electrical conductivity measurement, UV-Vis-NIR and FTIR spectroscopy. The samples were obtained as flexible films by pressing the powder at 180 °C for 5 min. The electrical conductivity showed a great dependence on the syntheses parameters. The higher value of the electrical conductivity was obtained for the oxidant/aniline molar ratio equal to 1 and p-toluenesulfonic acid-TSA/aniline ratio between 3 and 6. UV-Vis-NIR and FTIR spectra of the blend are similar to the doped PANI, indicating that the PANI is responsible for the high electrical conductivity of the blend. The electrical conductivity of blend proved to be stable as a function of temperature decreasing about one order at temperature of 100 °C. The route used to obtain the polymer blend showed to be a suitable alternative in order to obtain PVDF/PANI-TSA blends with high electrical conductivity.