Rubber‐toughened polypropylene/acrylonitrile‐co‐butadiene‐co‐styrene blends: Morphology and mechanical properties

The RTPP/ABS (rubber toughened polypropylene/poly (acrylonitrile‐co‐butadiene‐co‐styrene) blends, both noncompatibilized and compatibilized with polypropylene‐g‐polystyrene, were prepared by melt mixing in a Brabender Plasti‐Corder. As the torque ratio of RTPP and ABS was about 2, phase cocontinuity in the blends was achieved at ABS volume fractions around 0.16, which was evidenced by both microscopic analysis and mechanical testing. A new microscopic and image analysis technique was introduced, whose combination provides two semiquantitative parameters: structure roughness and structure cocontinuity. The latter parameter is closely associated with the predictive scheme based on the equivalent box model and percolation theory, which was used in this study. The predicted mechanical properties were confronted with the experimental data for tensile modulus, yield strength, and tensile impact strength. While the modulus of noncompatibilized blends is reasonably fitted by the model, the compatibilizer accounts for a positive deviation attributed to a strong interaction between the compatibilizer and the matrix. The yield strength of noncompatibilized blends indicates poor interfacial adhesion, which is so enhanced by the compatibilizer that no phase debonding occurs before yielding. Tensile impact strength, in contrast to modulus and yield strength, passes through a deep minimum for both types of blends; two tentative explanations of this detrimental behavior were suggested. POLYM. ENG. SCI., 47:582–592, 2007. © 2007 Society of Plastics Engineers.     

Crystallization and melting behavior of blends comprising poly(3‐hydroxy butyrate‐co‐3‐hydroxy valerate) and poly(ethylene oxide)

Blends of poly(3‐hydroxy butyrate‐co‐3‐hydroxy valerate) (PHBV) and poly(ethylene oxide) (PEO) were prepared by casting from chloroform solutions. Crystallization kinetics and melting behavior of blends have been studied by differential scanning calorimetry and optical polarizing microscopy. Experimental results reveal that the constituents are miscible in the amorphous state. They form separated crystal structures in the solid state. Crystallization behavior of the blends was studied under isothermal and nonisothermal conditions. Owing to the large difference in melting temperatures, the constituents crystallize consecutively in blends; however, the process is affected by the respective second component. PHBV crystallizes from the amorphous mixture of the constituents, at temperatures where the PEO remains in the molten state. PEO, on the other hand, is surrounded during its crystallization process by crystalline PHBV regions. The degree of crystallinity in the blends stays constant for PHBV and decreases slightly for PEO, with ascending PHBV content. The rate of crystallization of PHBV decreases in blends as compared to the neat polymer. The opposite behavior is observed for PEO. Nonisothermal crystallization is discussed in terms of a quasi‐isothermal approach. Qualitatively, the results show the same tendencies as under isothermal conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2776–2783, 2006     

Effect of organoclays on the thermal,mechanical, and oxygen barrier properties of poly(methylmethacrylate‐co‐acrylonitrile)/clay nanocomposites

The nanostructured hybrid materials of poly(methylmethacrylate‐co‐acrylonitrile) copolymer were synthesized with incorporation of two organically modified clays, Cloisite® 30B and 93A by in situ intercalative emulsifier‐free emulsion polymerization method. The synthesized products were characterized by Fourier transform infrared spectroscopy to get evidence of copolymerization and formation of copolymer‐clay nanocomposite. X‐ray diffraction study and transmission electron microscopy analysis revealed that the clays were successfully intercalated and exfoliated into the copolymer matrix. Thermal properties of the nanocomposites were studied as a function of clay content of different clay types by thermogravimetric analysis. The results showed significant effect of both the clays in enhancing thermal resistance of the materials. Mechanical properties of the composites were also found to be improved at optimum clay loading. Oxygen barrier property of these materials was measured and it was found that the oxygen permeability was reduced almost by half due to incorporation of clays at 3% loading. Further, it was observed that Cloisite® 93A was more effective for improvement in properties when compared with Cloisite® 30B in the hybrid materials. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

A new nanocomposite based on polylactic acid/butadiene rubber/clay: Morphology development and mechanical properties

In this work, several samples based on poly(lactic) acid (PLA)/butadiene rubber (BR) blend with and without nanoclay (Cloisite 30B) were prepared using an internal mixer. Various methods were used to characterize the samples, including scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD), rheometric mechanical spectrometer, stress–strain, and impact strength tests. The SEM results showed the droplet-matrix morphology for all prepared samples. With the incorporation of nanoclay, the mean diameter of the BR droplets generated within the PLA matrix decreased. AFM test revealed the placement of nanoparticles in the PLA phase, which was consistent with the thermodynamic prediction of their location. The XRD test showed that the interlayer space of nanoclay expanded by 86% due to the diffusion of polymer chains between them. In the rheology test, this resulted in an increment in modulus and viscosity at low frequencies for the nanocomposites compared to the simple blend. The highest elongation at break was observed for the PLA/BR blend containing 10 wt% BR with approximately 40 times its value for the neat PLA, while the impact resistance increased up to three times.     

PVC‐clay nanocomposites: Preparation,thermal and mechanical properties

PVC‐clay nanocomposites were prepared by melt blending of the polymer with an organically modified clay, both in the presence and in the absence of di(2‐ethylhexyl) phthalate (DOP). The clay can serve as a plasticizer for PVC in the absence of DOP. The nanocomposites were characterized by using X‐ray diffraction and transmission electron microscopy, and the materials were found to be largely intercalated. Thermal properties were evaluated by using thermogravimetric analysis, and the thermal stability was determined to be variable, depending upon the amounts of clay and DOP that were present. The fraction of polymer that remained at 600°C was significantly reduced in the presence of the clay, a result indicating that the clay had an effect on the course of the degradation of the PVC. The tensile strength of the nanocomposites increased as the fraction of clay increased, and the addition of a small amount of clay increased the elongation, but when additional clay was added, the elongation decreased.     

The effect of polylactic acid (PLA)/poly‐d‐lactide stereocomplex on the thermal and mechanical properties of various PLA/rubber blends

This study investigated the effect of polylactic acid (PLA)/poly‐d ‐lactide (PDLA) stereocomplex (ST) on the improvement of the mechanical and thermal properties of various rubber‐toughened PLAs. In this work, natural rubber (NR), synthetic polyisoprene rubber (IR), silicone rubber (SI), acrylic rubber (ACM), acrylic core–shell rubber (CSR), thermoplastic copolyester (TPE) and thermoplastic polyurethane (TPU) were chosen as the toughening agents. 5 wt% PDLA was melt‐blended with PLA to form ST crystals in the presence of 15 wt% rubber in an internal mixer at 180 °C and 50 rpm. It was found that the melting temperature of ST crystal (T_m,sc) and the impact strength of ST/rubber blends were strongly correlated with the rubber domain size. For the blends of ST with compatible rubbers (ACM, CSR, TPE and TPU), the rubber domain sizes tended to be smaller with higher T_m,sc and higher impact strength than the blends with incompatible rubbers (NR, IR and SI). However, the presence of ST crystals in PLA/incompatible rubber blends, especially the blends with NR and IR, led to a significant increase in the rubber domain size and plunges in tensile toughness and impact strength. On the other hand, the presence of these crystals in PLA/compatible blends did not change the rubber size or the impact strength significantly compared with those without ST crystals except in the case of ST/ACM, which resulted in a large increase in the impact strength. Among all rubber types, CSR provided the highest impact strength for both the PLA and ST systems. © 2019 Society of Chemical Industry     

Effect of water and crude oil on mechanical and thermal properties of epoxy‐clay nanocomposites

Epoxy‐clay nanocomposites were synthesized by high shear mixing (HSM) technique using diglycidyl ether of bisphenol A (DGEBA) epoxy reinforced by Nanomer I.30E nanoclay. Disordered intercalated with some exfoliated structure were found in the resultant nanocomposites. The fabricated samples were exposed to water and crude oil to investigate the effect of nanoclay addition on diffusivity and amount of liquid uptake. The results showed good improvement in the barrier properties of epoxy as a result of clay addition. The average reduction in diffusivity and maximum water uptake for nanocomposites containing 1% nanoclay were 51% and 8%, respectively. The maximum water uptake was about double the maximum oil ingress for both neat epoxy and nanocomposites. Obvious degradations in thermal and mechanical properties of neat epoxy and nanocomposites were observed as a result of liquid uptake; with less severe impact on nanocomposites. The reduction in glass transition temperature was about 8% for each 1% of water uptake for nanocomposites as compared to 15% for neat epoxy. The tensile strength and the elastic modulus of neat epoxy and nanocomposites were adversely affected by water and oil uptake while the fracture strain was slightly improved; a behavior found to be proportional to the amount of liquid uptake. The diffusion mechanism of water in neat epoxy was well predicted by Fickian model, while that of the nanocomposites was better fitted with Langmuir model. POLYM. COMPOS., 35:318–326, 2014. © 2013 Society of Plastics Engineers     

异氰酸酯对聚乳酸/热塑性聚氨酯共混物性能的影响

以4,4^′-二苯基甲烷二异氰酸酯（MDI）为反应增容剂，采用熔融共混法制备了不同MDI含量的聚乳酸/热塑性聚氨酯（PLA/TPU）共混物，采用傅里叶变换红外光谱仪（FTIR）、万能试验机、冲击试验机、扫描电子显微镜（SEM）、差示扫描量热仪（DSC）和旋转流变仪对共混物力学性能、微观形态、热性能和流变性能进行了研究。结果表明：MDI可以有效改善共混物的力学性能，当MDI质量分数为1%时，共混物力学性能最佳，缺口冲击强度为40.0kJ/m²，断裂伸长率为214.1%，与未加MDI的共混物相比，分别增加了4.3倍和5.8倍，拉伸强度稍有下降（47.6MPa）；SEM表明，MDI的加入提高了共混物的相容性，加入MDI后，共混物的断面由海-岛结构变为核-壳包覆结构，相界面作用力增强；DSC测试表明，共混物的玻璃化转变温度、冷结晶温度和熔融温度随着MDI含量的增加而升高；流变测试表明，MDI质量分数的增加，共混物呈现更显著的剪切变稀行为，推测共混反应机理为：MDI质量分数的增加，体系内依次发生PLA的扩链、支化和TPU的交联。     

Effect of thermal annealing on the mechanical and thermal properties of polylactic acid–cellulosic fiber biocomposites

Polylactic acid (PLA) biocomposites were produced by a combination of extrusion and injection molding with three cellulosic reinforcements (agave, coir, and pine) and contents (10, 20, and 30%). In particular, some samples were subjected to thermal annealing (105 °C for 1 h) to modify the crystallinity of the materials. In all cases, morphological (scanning electron microscopy) and thermal (differential scanning calorimetry, dynamical mechanical thermal analysis) characterizations were related to the mechanical properties (Charpy impact, tensile and flexural tests). The results showed that annealing increased the crystallinity for all the materials produced, but different mechanical behaviors were observed depending on fiber type and content. For example, annealing increased the impact strength and flexural modulus of PLA and PLA biocomposites (agave, coir, and pine), while decreasing their flexural strength. But the main conclusion is that fiber addition combined with thermal annealing can substantially increase the thermal stability of the studied materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43750.     

Influence of LiClO4 on the thermal,mechanical, and morphological properties of P(DMS‐co‐EO)/ P(EPI‐co‐EO) blends

The UV‐vis absorption, thermal analysis, ionic conductivity, mechanical properties, and morphology of a blend of poly(dimethylsiloxane‐co‐ethylene oxide) [P(DMS‐co‐EO)] and poly(epichlorohydrin‐co‐ethylene oxide) [P(EPI‐co‐EO)] (P(DMS‐co‐EO)/P(EPI‐co‐EO) ratio of 15/85 wt %) with different concentrations of LiClO₄ were studied. The maximum ionic conductivity (σ = 1.2 × 10^?4 S cm^?1) for the blend was obtained in the presence of 6% wt LiClO₄. The crystalline phase of the blend disappeared with increasing salt concentration, whereas the glass transition temperature (T_g) progressively increased. UV‐vis absorption spectra for the blends with LiClO₄ showed a transparent polymer electrolyte in the visible region. The addition of lithium salt decreased the tensile strength and elongation at break and increased Young's modulus of the blends. Scanning electron microscopy showed separation of the phases between P(DMS‐co‐EO) and P(EPI‐co‐EO), and the presence of LiClO₄ made the blends more susceptible to cracking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1230–1235, 2004     

Effect of organomodified clay on the reaction kinetics,properties and thermal degradation of nanocomposites based on poly(styrene‐co‐ethyl methacrylate)

In this research, synthesis of novel nanocomposites based on a poly(styrene‐co‐ethyl methacrylate) copolymer matrix was investigated with different types and amounts of organomodified montmorillonite (MMT) clays. The in situ polymerization technique was selected with dispersion of the MMT nanoparticles into the comonomer mixture and subsequent bulk radical polymerization. Reaction kinetics was measured gravimetrically and it was found that the existence of rigid phenyl rings in the organomodifier may result in a hindered reaction rate especially at high clay loadings. Structural characteristics of the nanocomposites formed were verified with XRD and Fourier transform infrared analysis and mainly intercalated/partially exfoliated structures were verified; their glass transition temperature was measured with DSC, and their molecular weight distribution and average molecular weights were measured with gel permeation chromatography. The latter was also used to measure the variation of the copolymer average molecular weight with conversion. Slightly higher average molecular weight and T_g values for the copolymer in the nanocomposites were measured, compared with neat copolymer. The thermal stability of the nanocomposites was measured with TGA and found to be significantly improved. One‐step degradation revealed the existence of macromolecular chains without defective structures. Finally, pyrolysis of the nanocomposite copolymers resulted in the production of both comonomers in high amounts, followed by some dimers or trimers. © 2013 Society of Chemical Industry     

Morphology and mechanical properties of polypropylene and poly(ethylene‐co‐methyl acrylate) blends

The morphology and mechanical properties of isotactic polypropylene (iPP) and poly(ethylene‐co‐methyl acrylate) (EMA) blends were investigated. Various EMA copolymers with different methyl acrylate (MA) comonomer content were used. iPP and EMA formed immiscible blends over the composition range studied. The crystallization and melting reflected that of the individual components and the crystallinity was not greatly affected. The size of the iPP crystals was larger in the blends than those of pure iPP, indicating that EMA may have reduced the nucleation density of the iPP; however, the growth rate of the iPP crystals was found to remain constant. The tensile elongation at break was greatly increased by the presence of EMA, although the modulus remained approximately constant until the EMA composition was greater than 20%. EMA with a 9.0% MA content provided the optimum effect on the mechanical properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 175–185, 2003     

共溶剂对聚乳酸相对分子质量及热性能的影响

以超临界二氧化碳(SC-CO2)为载体,分别以丙酮、无水乙醚、六氟异丙醇为共溶剂,合成聚乳酸(PLLA),并采用FT-IR、GPC和DSC等对所获得的聚合物进行了相对分子质量测定和结构性能表征,探讨了3种共溶剂对用SC-CO2为溶剂合成的PLLA相对分子质量及热性能的影响。结果表明,共溶剂对PLLA的相对分子质量、相对分子质量分布指数以及热性能影响较大;以丙酮为共溶剂时,可以获得最高相对分子质量为47 690且热性能较好的PLLA。     

Effect of clay on the properties of poly(styrene‐co‐acrylonitrile)–clay nanocomposites

Clay‐dispersed poly(styrene‐co‐acrylonitrile) nanocomposites (PSAN) were synthesized by a free radical polymerization process. The montmorillonite (MMT) was modified by a cationic surfactant hexadecyltrimethylammonium chloride. The structures of PSAN were determined by wide‐angle X‐ray diffraction and FTIR spectroscopy. The dispersion of silicate layers in the polymer matrix was also revealed by transmission electron microscopy (TEM). It was confirmed that the clay was intercalated and exfoliated in the PSAN matrix. The increased thermal stability of PSAN with the addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of PSAN were measured in the frequency range 100 Hz to 1 MHz at 35–70°C. It was found that the dielectric constant from the dipole orientation had been suppressed due to the intercalation of clay. The dielectric loss is strongly related to the residual sodium content of clay, which increases as the sodium content increases by the addition of clay. Copyright © 2004 Society of Chemical Industry     

Rheological,thermal, and mechanical properties of P (3HB‐co‐4HB) and P (3HB‐co‐4HB)/EVA blends

Poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)] fiber and P(3HB‐co‐4HB)/EVA fiber were obtained by single screw extrusion machine. The rheology of P(3HB‐co‐4HB) and P(3HB‐co‐4HB)/EVA blends was characterized by capillary rheometer, and the chemical groups of the blends were characterized with Fourier transform infrared spectroscopy (FT‐IR). The crystallization behavior and thermal, mechanical and elastic properties of the fibers were measured by differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and single fiber strength tester, respectively. Besides, the moisture regain and drying shrinkage rates of the fibers were tested. These results showed that P(3HB‐co‐4HB)/EVA blends have better flowability, crystallinity, and thermal stability than P(3HB‐co‐4HB) fiber. The fracture strength of the P(3HB‐co‐4HB)/EVA fiber decreases with increasing the EVA content, but the elongation at break shows the contrary tendency. The rebound resilience ratio of P(3HB‐co‐4HB)/EVA fiber reaches 100%. Both moisture regain and drying shrinkage increase first and then decrease with increasing the EVA content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41206.     

Synthesis and properties of collagen/polylactic acid blends

Polylactic acid (PLA) is a biodegradable aliphatic polyester that is suitable for use in many fields related to medical treatment. This article reviews the glass transition temperature (T_g), the biodegradable rate of PLA blended with collagen (Col), and its mechanical properties through tensile, bending and impact testing, thermal analysis (DSC), scanning electron microscopy (SEM), and enzymatic hydrolysis. The results of the mechanical and SEM examination demonstrated partial biocompatibility. The T_g and crystallinity (x_c) of the blends decreased with increasing collagen content. The tensile strength and bending strength changed from 53.826Mpa and 102.261Mpa to 11.707Mpa and 24.994Mpa, respectively. It was also found that the enzymatic hydrolysis rate of PLA increased with increasing collagen content. The weight of the blends decreased to half of the original weight after more than five weeks. Viscosity([η]) and molecular weight (M_v) changed slowly in the period of enzymatic hydrolysis. It was concluded that the introduction of the collagen phase clearly diminished the mechanical properties of PLA, but the biodegradable property was improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1670–1675, 2004     

Effect of clay platelet dispersion as affected by the manufacturing techniques on thermal and mechanical properties of PMMA‐clay nanocomposites

In this work, the properties of Poly(methyl methacrylate) (PMMA)‐clay nanocomposites prepared by three different manufacturing techniques viz., solution mixing, melt mixing, and in‐situ bulk polymerization in presence of clay were studied. Morphological analysis revealed that the extent of intercalation and dispersion of the nanoclay were relatively higher in the in‐situ polymerized nanocomposites than those of solution and melt blended nanocomposites. Differential Scanning Calorimetric study indicated maximum increment in T_g of the PMMA in the in‐situ polymerized PMMA‐clay nanocomposites. Thermo gravimetric analysis showed improved thermal stability of PMMA in all the nanocomposites and the maximum improvement was for in‐situ polymerized nanocomposites. The storage moduli of all the nanocomposites were higher than the pure PMMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of curauá fiber content on the properties of poly(hydroxybutyrate‐co‐valerate) composites

Poly(hydroxybutyrate‐co‐valerate) (PHBV), a biodegradable polymer produced from a renewable microbiological source, was reinforced with varying amounts of curauá fibers (CFs). The composites were produced using a twin‐screw extrusion and injection process. Scanning electron microscopy showed poor adhesion between the matrix and fiber; however, mechanical testing showed that the addition of the fiber improved the mechanical properties. Composites with 20 and 30 wt% CF displayed the best properties; however, because of the difficulties in processing composites with a CF content of 30 wt%, it was concluded that the ideal content of CF was 20 wt%. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Effect of miscibility on mechanical and thermal properties of poly(lactic acid)/ polycaprolactone blends

Binary blends based on poly(lactic acid) (PLA) and polycaprolactone (PCL) were prepared by melt mixing in a twin‐screw co‐rotating extruder in order to increase the low intrinsic elongation at break of PLA for packaging applications. Although PLA and PCL show low miscibility, the presence of PCL leads to a marked improvement in the ductile properties of PLA. Various mechanical properties were evaluated in terms of PCL content up to 30 wt% PCL. In addition to tensile and flexural properties, Poisson's ratio was obtained using biaxial extensometry to evaluate transversal deformations when axial loads are applied. Very slight changes in the melt temperature and glass transition temperature of PLA are observed thus indicating the low miscibility of the PLA–PCL system. Field emission scanning electron microscopy reveals some interactions between the two components of the blend since the morphology is characterized by non‐spherical polycaprolactone drops dispersed into the PLA matrix. In addition to the improvement of mechanical ductile properties, PCL provides higher degradation rates of blends under conditions of composting for contents below 22.5% PCL. © 2016 Society of Chemical Industry     

Polyhydroxybutyrate/acrylonitrile‐g‐(ethylene‐co‐ propylene‐co‐diene)‐g‐styrene blends: Their morphology and thermal and mechanical behavior

Polyhydroxybutyrate (PHB) is a biodegradable bacterial polyester emerging as a viable substitute for synthetic, semicrystalline, nonbiodegradable polymers. An elastomer terpolymer of acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene (AES) was blended with PHB in a batch mixer and in a twin‐screw extruder to improve the mechanical properties of PHB. The blends were characterized with differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopy, and impact resistance measurements. Despite the narrow processing window of PHB, blends with AES could be prepared via the melting of the mixture without significant degradation of PHB. The blends were immiscible and composed of four phases: poly(ethylene‐co‐propylene‐co‐diene), poly(styrene‐co‐acrylonitrile), amorphous PHB, and crystalline PHB. The crystallization of PHB in the blends was influenced by the AES content in different ways, depending on the processing conditions. A blend containing 30 wt % AES presented impact resistance comparable to that of high‐impact polystyrene, and the value was about 190% higher than that of pure PHB. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008