Rheological behavior of polyester blend and mechanical properties of the polypropylene–polyester blend fibers

The article deals with method of preparation, rheological properties, phase structure, and morphology of binary blend of poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) and ternary blends of polypropylene (PP)/(PET/PBT). The ternary blend of PET/PBT (PES) containing 30 wt % of PP is used as a final polymer additive (FPA) for blending with PP and subsequent spinning. In addition commercial montane (polyester) wax Licowax E (LiE) was used as a compatibilizer for spinning process enhancement. The PP/PES blend fibers containing 8 wt % of polyester as dispersed phase were prepared in a two‐step procedure: preparation of FPA using laboratory twin‐screw extruder and spinning of the PP/PES blend fibers after blending PP and FPA, using a laboratory spinning equipment. DSC analysis was used for investigation of the phase structure of the PES components and selected blends. Finally, the mechanical properties of the blend fibers were analyzed. It has been found that viscosity of the PET/PBT blends is strongly influenced by the presence of the major component. In addition, the major component suppresses crystallinity of the minor component phase up to a concentration of 30 wt %. PBT as major component in dispersed PES phase increases viscosity of the PET/PBT blend melts and increases the tensile strength of the PP/PES blend fibers. The impact of the compatibilizer on the uniformity of phase dispersion of PP/PES blend fibers was demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4222–4227, 2006     

Rheological and physical properties of polyarylate/LCP blend systems

A polyarylate Unitika U-Polymer 100 (PAR) was melt blended with a thermotropic liquid crystalline polymer (LCP) Vectra A950, and the processingmorphology-properties relations were investigated. Inclusion of LCP slightly reduced T_g of PAR. The PAR/LCP blend with the LCP content higher than 50 wt% exhibited a noticeable yield stress, particularly in the vicinity of crystal-to-nematic transition temperature (T_cn). LCP lowered the blend viscosity above T_cn and seemed to play a role as processing aid. The tensile strength of the blends was increased with increasing spin draw ratio and level of LCP, and the spinning temperature influenced tensile strength. The relaxation behavior under dynamic shear and resultant blend morphology based on WAXD and SEM analyses are discussed as well.     

Structure and physical properties of silk fibroin/polyacrylamide blend films

This article deals with the characterization of blend films obtained by mixing silk fibroin (SF) and polyacrylamide (PAAm). The DSC curves of SF/PAAm blend films showed overlapping of the main thermal transitions characteristic of the individual polymers. The exothermic peak at 218°C, assigned to the β‐sheet crystallization of silk fibroin, slightly shifted to a lower temperature by blending. The weight‐retention properties (TG) of the blend films were intermediate between those of the two constituents. The TMA response was indicative of a higher thermal stability of the blend films, even at low PAAm content (≤25%), the final breaking occurring at about 300°C (100°C higher than pure SF film). The peak of dynamic loss modulus of silk fibroin at 193°C gradually shifted to lower temperature in the blend films, suggesting an enhancement of the molecular motion of the fibroin chains induced by the presence of PAAm. Changes in the NH stretching region of silk fibroin were detected by FTIR analysis of blend films. These are attributable to disturbance of the hydrogen bond pattern of silk fibroin and formation of new hydrogen bonds with PAAm. The values of strength and elongation at break of blend films slightly improved at 20–25% PAAm content. A sea–island structure was observed by examining the air surface of the blend films by scanning electron microscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1563–1571, 1999     

Structural and physical properties of silk fibroin/alginate blend sponges

Silk fibroin/alginate blend sponges were examined through IR spectroscopy, X‐ray diffractometry, and differential scanning calorimetry to determine the structural changes of silk fibroin. The effects of fibroin/alginate blend ratios on the physical and mechanical properties were investigated to discover the feasibility of using these blend sponges as biomedical materials such as wound dressings. The compressive modulus of silk fibroin was increased up to 30 kPa, from 7.1 kPa, by blending with alginate. Thermal crystallization behavior of fibroin induced by heat treatment was restricted by blending with alginate. In spite of that, the structural characteristics of fibroin were not changed by incorporation with alginate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2174–2179, 2004     

舒适性聚酯纤维研究Ⅰ.添加剂含量对共混纤维碱水解性能的影响

将含有间苯二甲酸双羟乙酯 5 磺酸钠(SIPE)成分的添加剂与聚酯共混纺丝形成系列共混聚酯纤维,其碱水解行为有别于传统的聚酯纤维:在一定温度下,它的碱减量率与时间之间呈现较好的线性关系,并且取决于初始碱浓度。由于结构因素上的原因,碱减量的程度随添加剂添加数量的增加而增大,而且这种影响随处理条件如处理时间、碱浓度以及处理温度等的提高而加剧。在一定数量的添加剂(<50%)下,添加剂组分与聚酯组分间能较好地相容并成微纤状形式分散于聚酯纤维中,这种分散形式对纤维的碱处理性能有较大的影响。从碱处理后的SEM照片可以看到许多微细狭长的缝隙,它们的形成将有助于水分的快速散发。     

Reaction kinetics and physical properties of unsaturated polyester modified with methylacyloxylpropyl-POSS

The polyhedral oligomeric silsesquioxanes which contains methylacryloylpropyl group (MAP-POSS) was synthesized and used to modify unsaturated polyester resin (UPR). The cure kinetics was investigated by isothermal DSC technique. The mechanical and electrical properties of fiberglass-reinforced laminate were determined. The result shows that the reaction can be described by a Kamal autocatalytic model which has two reaction rate constants k ₁ and k ₂, and two apparent activation energies E _a1 and E _{a 2} are 98.12 kJ/mol and 74.01 kJ/mol, respectively. UPR and MAP-POSS can co-cure in free radical polymerization. When the MAP-POSS content is 5 wt%, the impact and tensile strength of fiberglass-reinforced laminate enhanced 10% and 6%, respectively, and has better electrical properties than no MAP-POSS. The dielectric constant ε and dielectric loss tanδ are all decrease. The surface resistance ρ _s is 4.7 times higher than pure UPR laminates     

Proton conducting blend membranes: physical,morphological and electronic properties

Blend membranes of sulfonated poly(ether ether ketone) (SPEEK) and sulfonated polyetherimide (SPEI) have been prepared and investigated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cell (DMFC). Polymers were dissolved in N-methyl-2-pyrrolidone (NMP) in different mixing ratios and membranes were casted using a semi-automatic casting machine on a pre-cleaned glass plate. The influence of SPEI percentage on ion exchange capacity (IEC), water uptake, methanol permeability and proton exchange capacity have been investigated. Blend membranes showed slightly better IEC, water uptake and methanol crossover properties as compare to pure SPEEK; but proton conductivity was slightly lower than that of pure SPEEK membrane. Membrane morphology was investigated by FESEM, TGA and AFM. Overall, a homogeneous surface was observed for most of the blend membranes, with minor phase separation at higher SPEI contents samples. AFM image of the membrane surface shows nanoscale surface roughness.     

Alkaline dyeing of polyester and polyester/cotton blend fabrics using sodium edetate

An alkaline dyeing of polyester with an alkali‐stable disperse dye, Dianix® Scarlet AD‐RG, was developed using sodium edetate as an alkaline buffering agent. The results obtained indicate the suitability of using sodium edetate for alkaline dyeing of polyester when compared with the control alkaline dyeing using Dianix AD system. Selected mono and bifunctional reactive dyes were used in combination with the alkali‐stable disperse dye for dyeing of polyester/cotton blend. Different dyeing methods for cotton and polyester/cotton blend fabrics using sodium edetate were evaluated in comparison with their respective control alkaline dyeing methods. The results of using sodium edetate in one‐bath two‐stage and two‐bath dyeing of polyester/cotton blend were comparable with that of the control dyeing method. Particularly, no change in the leveling and fastness properties was evaluated for all samples irrespective of the dyeing method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and physical properties of konjac glucomannan–polyacrylamide blend films

The blend films of konjac glucomannan (KGM) and polyacrylamide (PAAm) were prepared by using the solvent‐casting technique. Transparent blend films were obtained in all blending ratios. The physical properties of the films were investigated by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and by measurement of mechanical properties. The results indicated the occurrence of intra‐ and intermolecular interactions of the pure components, as well as the intermolecular interactions between KGM and PAAm through hydrogen bond formation. The thermal stability and mechanical properties of both tensile strength and elongation at break of the films were improved by blending KGM with PAAm. It was worth noting that the blend film had the greatest tensile strength when the KGM content in the blend films was around 30 wt %. Surface morphology of the films observed by SEM was consistent with the above‐noted results. Furthermore, the water absorbability of the blend films was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 882–888, 2001     

Study on physical properties of blend films from gelatin and polyacrylamide solutions

Blend films of gelatin and polyacrylamide (PAAm) were prepared by casting the mixed aqueous solutions of both samples in different ratios. All blend films obtained are optically clear to the naked eye. The structure and physical properties of the films were studied by FT‐infrared (FTIR), wide‐angle X‐ray diffraction (WAXD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The experimental results show that the blend films exhibit the higher thermal stability and improved mechanical properties of both tensile strength and elongation at break in dry states, which suggests the occurrence of interaction detected by FTIR between gelatin, PAAm, and water molecules in the films. The morphological transition of the blend films from gelatin‐like to PAAm‐like was observed by SEM. Furthermore, moisture content and water swelling property of the blend films were also investigated, which was consistent with the results from SEM. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 949–955, 2002     

A compatibilizer for a blend of polysulfone with a liquid crystalline polyester

A ternary blend of polysulfone (PSF), a thermotropic liquid crystalline polymer (TLCP), and a compatibilizer was investigated. The TLCP was composed of terephthalic acid (TPA), m-phthalic acid (MPA), p-acetoxybenzoic acid (Ac-HBA), and 4,4′-diacetoxy bisphenyl (Ac-BP). The compatibilizer was a block copolymer of low molecular weight polysulfone and a rigid-rod chain. Morphological investigations showed that the TLCP in the ternary system exhibited improved adhesion and dispersion in a much finer scale than in binary blends of PSF/TLCP prepared under the same processing conditions. Differential scanning calorimetry confirmed this result. Significant improvements were seen in the values of tensile modulus and strength.     

Improvement of physical properties of crosslinked alginate and carboxymethyl konjac glucomannan blend films

Blend films from carboxymethyl konjac glucomannan and sodium alginate in different ratios were prepared by blending 4 wt % sodium alginate aqueous solution with 2 wt % konjac glucomannan aqueous solution. After crosslinking with 5 wt % calcium chloride aqueous solution, the blend films formed a structure of semi‐interpenetrating networks. The structure and physical properties of both uncrosslinked and crosslinked films were characterized by Fourier transformed infrared spectra (FTIR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests. The results indicated that the mechanical properties and the thermal stability of the films were improved by blending sodium alginate with carboxymethyl konjac glucomannan due to the intermolecular hydrogen bonds between sodium alginate and carboxymethyl konjac glucomannan. The crosslinked blend films with Ca²⁺, compared with uncrosslinked blend films, exhibited further improved physical properties due to the formation of a semi‐IPN structure. Furthermore, the degree of swelling of the crosslinked films was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2554–2560, 2002     

乙基纤维素与聚苯乙烯共混体系的相溶性研究

用紫外光谱、X射线衍射和DSC、偏光显微锐、相差显微镜和电镜等方法研究了乙基纤维素-聚苯乙烯共混体系的相溶性。结果表明该体系为部分相溶体系。     

Low‐profile mechanisms in a PVAc/polyester blend

The different steps associated with the curing of a PVAc/polyester blend are identified and correlated to the mechanism of shrinkage control in the presence of a low‐profile additive (LPA). Poly(vinyl acetate) (PVAc) is used as a LPA and is shown to induce a phase separation upon curing that leads to an interconnected globule morphology. This morphology strongly modifies the rheokinetics of the blend compared to that of the neat polyester resin. In particular, the presence of PVAc delays the cure kinetics and the gel time. A comparison between these delays, called shift times, demonstrates an increase in the gel conversion of polyester in the presence of PVAc. This, coupled to the thermal expansion of PVAc at the early stages of curing, contributes to the low‐profile effect. Microvoids in the LPA‐rich phase, which are believed to play a key role in the mechanism of shrinkage control, are efficient at the later stages of curing and during cooling and complete the low‐profile effect. However, it is also shown that the formation of microvoids may indirectly induce macroscopic voids that could be at the origin of pinholes at the surface of the parts molded with this material. POLYM. ENG. SCI. 46:303–313, 2006. © 2006 Society of Plastics Engineers     

Self-vulcanizable rubber blend based on neoprene and carboxylated nitrile rubber: Effect of blend ratio on miscibility and physical properties

Mill mixed blend of neoprene and carboxylated nitrile rubber can be vulcanized during molding at high temperatures (180°C) in the absence of any vulcanizing agent, which is supported by FTIR studies. The extent of vulcanization reaction depends not only upon the molding time but also on the blend ratio. Dynamic mechanical analyses and differential scanning calorimeter studies show that neoprene and carboxylated nitrile rubber are not miscible at the segmental level in the self-vulcanized blend.     

硅灰石/高岭土共混物对NR硫化胶物理性能的影响

研究硅灰石 /高岭土共混物对NR硫化胶物理性能的影响。结果表明 ,无论硅灰石和高岭土是否改性 ,当二者共混比为 2 5 / 2 5时 ,填充NR硫化胶的拉伸强度最大 ,其它物理性能均较好 ;改性硅灰石或改性高岭土填充NR硫化胶的综合物理性能分别优于未改性硅灰石或未改性高岭土填充胶。     

Effect of nano-sized calcium carbonate on cure kinetics and properties of polyester/epoxy blend powder coatings

Today's strict environmental laws pose significant challenges for coating's formulators to look for eco-friendly products. Powder coatings, particularly polyester/epoxy blends have demonstrated their ability as alternatives to traditional solvent-borne coatings. Recently, the use of nanoparticles such as nano-CaCO₃ (nCaCO₃) has been suggested as a beneficial strategy towards powder coating application with improved properties. Here, we study the effect of nCaCO₃ on morphology, cure behavior, adhesion and hardness of polyester/epoxy systems. The nanoparticles shape, size and dispersion state were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. Furthermore, isothermal cure characterization of the neat and filled systems was performed using a torque rheometer. The most important finding based on the rheological studies was the catalytic effect of nCaCO₃ on cure reaction of polyester/epoxy, leading to the shorter curing time. Moreover, the kinetic analyses of rheograms revealed a marked decrease in the activation energy of the cure process upon raising nCaCO₃ content. Interestingly, pull-off adhesion and hardness tests showed that the hardness and adhesion strength were dramatically increased by the addition of nCaCO₃ into the polyester/epoxy system compared to pure blend resin. Therefore, considering the strong competition in powder coating market, the use of nCaCO₃ as a commercial and inexpensive nanofiller is necessary not only to reduce the dwell time which has benefits in terms of the energy consumption and economics, but also to improve the performance of final polyester/epoxy coating.     

Formulation and optimization of sucrose polyester physical properties by mixture response surface methodology

The physical properties of sucrose polyester (SPE), prepared from different composite blends of fatty acid methyl esters (FAME) of safflower oil, palm oil, and peanut oil, were evaluated by mixture response surface methodology. Optimum combinations of fatty, acids to achieve specific physical properties of SPE were determined. The SPE most similar in physical properties to peanut oil was obtained with a 55:45 molar ratio of mixed FAME from safflower oil and peanut oil. The physical properties of SPE were significantly affected by the degree of saturation and the average chainlength of their composite fatty acids.     

Influence of air-cooling time on physical properties of thermoplastic polyester powder coatings

Properties such as the specular gloss, adhesive strength, viscoelasticity, and impact resistance of thermoplastic polyester powder coating film were studied as a function of air-cooling time. Thermoplastic polyester resin is known for the fact that the heating condition has an effect on the degree of crystallinity. We focused on the relationship between the air-cooling time employed in the film preparation process and the degree of crystallinity. The test pieces were dipped into a fluidized polyester powder vessel, and then cooled in air to form the film. We refer to this cooling time in air as the “air-cooling time”. It was found that the degree of crystallinity increased as the air-cooling time increased. As the degree of crystallinity increased, the specular gloss, adhesive strength, viscosity and impact resistance decreased. We therefore found that the improvement in film performance is related to the reduction in the air-cooling time. The importance of this phenomenon is considered in relation to the widespread use of thermoplastic polyester resin. Similar behavior is expected for other polyester powder coatings.     

回用聚酯的熔融共混改性研究进展

综述了国内外回用聚对苯二甲酸乙二酯(R-PET)熔融共混改性的研究进展。异氰酸酯及均苯四酸二酐等扩链剂共混改性R-PET,通过共混熔融挤出,可提高R-PET的相对分子质量;有机聚合物如常规PET、聚烯烃(聚乙烯、聚丙烯以及接枝共聚物)、聚碳酸酯及聚碳酸酯的多组分混合物等共混改性R-PET,可提高共混材料力学性能;玻璃纤维、岩石纤维以及纳米有机粘土共混改性R-PET,可获取增强复合材料。