The Mechanical Properties,Compatibility, and Thermal Stabilities of POE-Graft-Methyl Methacrylate and Acrylonitrile(POE-g-MAN)/ Styrene-Acrylonitrile Copolymer (SAN Resin) Blends

POE-graft-methyl methacrylate and acrylonitrile (POE-g-MAN) was prepared by graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto polyethylene-octene copolymers (POE) with suspension polymerization. POE-g-MAN/SAN resin blends (AOMS) were prepared by blending POE-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The mechanical properties, compatibility, and thermal stabilities of AOMS were studied. The notched impact strength of the blends reached 54.0 kJ/m² when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN, benzoyl peroxide dosage, and POE content in AOMS were 15 wt%, 1.0 wt%, and 25 wt%, respectively. Transmission electron microscopy analysis showed that the highest toughness occurred when the size of POE-g-MAN particles and the surface-to-surface inter-particle distance were proper. Scanning electron microscopy analysis indicated that the AOMS fracture surface had plastic flow visible, which looked like a fibril morphology when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN was 15 wt%. The toughening mechanism of AOMS was shear yielding of the matrix, which endowed AOMS with remarkable toughness. Dynamic mechanical thermal analysis showed that the compatibility of the POE phase and SAN phase improved after graft copolymerization of MMA and AN onto POE. When the grafting chain polarity was appropriate, the miscibility between POE-g-MAN and SAN resin was the best. Thermogravimetry analysis showed that thermal stability of AOMS increased with increasing AN units in POE-g-MAN.     

Toughening Effect of Poly(ethene-co-1-butene)-graft-methyl Methacrylate and Acrylonitrile on Styrene-acrylonitrile Copolymer (SAN)

Poly(ethene-co-1-butene)-graft-methyl methacrylate-acrylonitrile (PEB-g-MAN), synthesized by suspension grafting copolymerization of methyl methacrylate and acrylonitrile onto PEB, was blended with styrene-acrylonitrile copolymer (SAN). The mechanical properties, phase structure, toughening mechanism, miscibility, and thermal stability of the SAN/PEB-g-MAN blends were studied using a pendulum impact tester, tension tester, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TG). The results showed that PEB-g-MAN has an excellent toughening effect on SAN resin. The notched impact strength of the blends (containing 25 wt% PEB) was 63.3 kJ/m², which was nearly 60 times that of SAN resin. The brittle-ductile transition of SAN/PEB-g-MAN blends occurred when the weight percentage of PEB was between 17.5 and ～20 wt%. SAN and PEB-g-MAN were partially miscible. The toughening mechanism of the blends changed with the PEB content. When the PEB content was low, the toughening mechanism of the blends was branching and termination of cracks with slight cavitation. As the content of PEB increased, the toughing mechanism gradually changed from branching and termination of crack with slight cavitation to both branching and termination of crack and cavitation, to extensive cavitation, and finally to shear yielding accompanied by cavitation. The phase structure of the blends changed from a “sea-island’’ structure to a cocontinuous structure as the PEB content increased. ATG analysis showed that the thermal properties of the SAN resin in the blends were enhanced by adding the PEB-g-MAN.     

Toughening Effect of Ethylene Propylene DieneTerpolymer-Graft-Styrene-Acrylonitrile Copolymer (EPDM-g-SAN) on SAN Resin

The reaction product EPDM-g-SAN, synthesized by suspension graft copolymerization of styrene (St) and acrylonitrile (AN) in the presence of ethylene-propylene-diene terpolymer (EPDM), was blended with a commercial styrene-acrylonitrile copolymer (SAN resin) to prepare AES blends with high impact strength. The effects of AN mass percentage in the St-AN comonomer mixture (f _AN), EPDM mass percentage in the feed of EPDM and St-AN (f _EPDM) and reaction time on monomer conversion ratio (CR), grafting ratio (GR), and AES notched Izod impact strength were characterized. The notched Izod impact strength of AES containing 15 wt% EPDM reached its maximum with f _AN of 40 wt% and f _EPDM of 45 wt%; this was attributed to the polarity of the SAN copolymer obtained being appropriate with that of the SAN resin matrix. The dependences of GR and the notched Izod impact strength of AES containing 25 wt% EPDM on the reaction time were in rough agreement. The effect of EPDM content on the AES notched Izod impact strength indicated that the brittle-ductile transition of AES occurred for an EPDM content from 12.5 to 15 wt%. TEM and SEM analysis showed that the phase structure of AES exhibited a “salami” like structure, and the toughening mechanism of AES was shear yielding of the SAN resin matrix, which endowed AES with excellent toughness.     

A Study of the Synthesis of EPDM-g-MAN and Toughness of its Blend with SAN (AEMS)

Ethylene–propylene–diene–methyl methacrylate/acrylonitrile terpolymers (EPDM-g-MAN) were synthesized by comonomers methyl methacrylate and acrylonitrile (MMA-AN) grafted on EPDM macromolecules with solution graft copolymerization. The engineering plastics of the blend of EPDM-g-MAN with SAN (AEMS) were prepared by blending EPDM-g-MAN with SAN resin. The effect of AN/MMA-AN weight percentage (f _AN) on monomer conversion ratio, grafting ratio, and grafting efficiency of the graft copolymerization and the notched Izod impact strength of AEMS were investigated. The notched Izod impact strength of AEMS, prepared by blending SAN with EPDM-g-MAN, was synthesized under our optimum S2 reaction conditions, with EPDM/MMA-AN weight proportion of 50/50 and f _AN of 10 wt%, presenting a peak with the maximum value of 61.0 kJ/m². The microstructure of AEMS prepared with S2 reaction conditions showed that when the polarity of EPDM-g-MAN was appropriate, the EPDM phase formed a pseudocontinuous phase in the SAN matrix and the interfacial adhesion was strong, which could induce shear yielding of the SAN matrix. Differential scanning calorimetry analysis showed that there was good compatibility between SAN resin and EPDM-g-MAN synthesized with f _AN of 10 wt% and a EPDM/MMA-AN weight ratio of 50/50.     

Mechanical,Thermal, and Rheological Properties of EPDM-graft-methyl Methacrylate and Styrene (EPDM-g-MS)/Methyl Methacrylate-Styrene Copolymer (MS Resin) Blends

EPDM-graft-methyl methacrylate and styrene (EPDM-g-MS) were synthesized by solution graft copolymerization of methyl methacrylate (MMA) and styrene (St) onto ethylene-propylene-diene terpolymer (EPDM). EPDM-g-MS/MS resin blends (MES) tht were prepared by melt blending EPDM-g-MS and methyl methacrylate-styrene copolymer (MS resin). The mechanical properties, compatibility, thermal stabilities and rheological properties of MES were studied by the pendulum impact tester and the tension tester, differential scanning calorimetric (DSC), thermogravimetry analysis (TGA), and the capillary rheometry, respectively. The results showed that EPDM-g-MS had an excellent toughening effect on MS resin; the notched Izod impact strength of MES reached 20.7 kJ/m² when EPDM content in MES was 25 wt%, about 14 times that of MS resin. EPDM-g-MS and MS resin were partially compatible, and the compatibility increased with an increasing MMA/St ratio of EPDM-g-MS. MES had excellent heat-resistance, which increased as the EPDM content in MES and MMA/St ratio of EPDM-g-MS rose. MES melt flow confirmed pseudoplastic flow characteristics. The apparent viscosity (η _a ) of MES decreased with an increasing shearing rate (γ) and temperature, but increased with an increasing EPDM content in MES and MMA/St ratio of EPDM-g-MS. The flow activation energy of MES was lower than that of MS resin.     

Impact of γ-rays on constructional,optical and thermal behavior of alkaline and non alkaline low density polyethylene

ABSTRACT

In this study, we investigated the graft copolymerization of methyl methacrylate (MMA) onto low-density polyethylene (LDPE) in the presence of aniline as an inhibitor by gamma radiation. An alkaline treatment was carried out for the prepared graft copolymer. The structural properties of the prepared samples were examined via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD peaks were slightly shifted, indicating an interaction between MMA and the polyethylene matrix. The morphology of the samples confirmed the homogenous grafted phase scattered onto the LDPE surface. Analysis of the absorption spectra indicated an allowed indirect transition mechanism. The Urbach energy (E_U) results showed that the value of the E_U for grafted LDPE was found to be higher than that of pure LDPE—up to 15?kGy irradiation dose, although this value decreases upon grafting. However, the value of the E_U for alkaline-treated grafted films decreases systematically by increasing the degree of grafting. The thermogravimetric analysis (TGA) of the sample indicated that the thermal stability of LDPE samples is significantly changed by grafting MMA onto it. Horowitz and Metzger's models were utilized to measure the activation energy of the thermal decomposition of all samples.     

Effect of Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile)’s Core/shell Ratio on Mechanical and Thermal Properties of Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile)/α-methylstyrene-acrylonitrile Binary Blends

Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile) terpolymer (PBA-g-SAN) with different core/shell ratios and α-methylstyrene-acrylonitrile (α-MSAN) were mixed via melt blending (25/75, W/W). It was found that the core/shell ratio of PBA-g-SAN played an important role in the toughening of rigid α-MSAN. According to an analysis of the impact strength and the morphologies of the impact fractured surfaces, the optimum core/shell ratio with the highest toughening efficiency was 60/40. Considering the results of dynamic mechanical thermal analysis (DMTA), the blends retained the high glass transition temperature (T_g) of α-MSAN because of the immiscibility between the two components. Moreover, increasing the core/shell ratio did not result in sacrificing the heat distortion temperature of the blends, which was attributed to the almost unchanged high temperature T_g of α-MSAN. The tensile strength, flexural strength, and modulus declined slightly with the increasing core content of PBA-g-SAN, which suggested that the stiffness of the blends decreased with the increasing core/shell ratio. This study showed that 60/40 was the optimum core/shell ratio used for toughening modification; it achieved a good balance between mechanical and heat resistance performance.     

Ultrasound-assisted synthesis of poly(MMA–co–BA)/ZnO nanocomposites with enhanced physical properties

The present study reports synthesis and characterization of poly(MMA–co–BA)/ZnO nanocomposites using ultrasound-assisted in-situ emulsion polymerization. Methyl methacrylate (MMA) was copolymerized with butyl acrylate (BA), for enhanced ductility of copolymer matrix, in presence of nanoscale ZnO particles. Ultrasound generated strong micro-turbulence in reaction mixture, which resulted in higher encapsulation and uniform dispersion of ZnO (in native form – without surface modification) in polymer matrix, as compared to mechanical stirring. The nanocomposites were characterized for physical properties and structural morphology using standard techniques such as XRD, FTIR, particle size analysis, UV–Visible spectroscopy, electrical conductivity, TGA, DSC, FE-SEM and TEM. Copolymerization of MMA and BA (in presence of ZnO) followed second order kinetics. Thermal stability (T_10% = 324.9 °C) and glass transition temperature (T_g = 67.8 °C) of poly(MMA-co-BA)/ZnO nanocomposites showed significant enhancement (35.1 °C for 1 wt% ZnO and 15.7 °C for 4 wt% ZnO, respectively), as compared to pristine poly(MMA–co–BA). poly(MMA–co–BA)/ZnO (5 wt%) nanocomposites possessed the highest electrical conductivity of 0.192 μS/cm and peak UV absorptivity of 0.55 at 372 nm. Solution rheological study of nanocomposites revealed enhancement in viscosity with increasing ZnO loading. Maximum viscosity of 0.01 Pa-s was obtained for 5 wt% ZnO loading.     

Investigation of Pendant Group and Chain Segment Motions in P(MMA/BA) Copolymers by Thermally Stimulated Depolarization Current

Poly(methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (M_η ～2×10⁵) with different mass percentages of MMA were synthesized by the method of solution polymerization. Thermally stimulated depolarization current (TSDC) technique was used to investigate the effect of copolymerization on pendant group and chain segment motions. Three TSDC peaks were observed over the temperature range from 310 to 400 K. The highest temperature, ρ peak originates from the detrapping of trapped charge carriers. The lower temperature, α peak corresponds to the glass transition. The activation energy of the α relaxation decreases from 1.2 eV for PMMA to 0.98 eV for MMA(75)/BA(25). In the fitting process, another peak, β′, is separated on the low temperature side. The apparent energy barrier of the β′ for PMMA is 0.80 eV. The β′ relaxation is thought to correspond to the motion of pendant groups including intra‐ and inter‐molecular interactions. All three peaks move to lower temperatures with an increase in BA component, and the activation energy for the α and β′ relaxations also decreases with the increase of BA component in copolymers, indicating that the flexible side groups of BA have an effect of plasticization on the glass transition and motion of pendent groups. The temperatures of the α and β′ peaks of P(MMA/BA) copolymers follow the Fox equation. Fitting results gives the α peak at 238 K and β′ peak at 225 K for polybutyl acrylate (PBA).     

Thermal and mechanical properties of gamma-irradiated prevulcanized natural rubber latex/low nitrosamines latex blends

Thermal and mechanical properties of blended radiation prevulcanized natural rubber latex (RVNRL) and low nitrosamines latex (LNL) were studied. RVNRL was blended with LNL at various composition ratios. From the tensile test, it was found that the optimum tensile value was attained at a total blending ratio of 70% RVNRL and 30% LNL. Latex blending with optimum tensile strength was then subjected to gamma irradiation at various doses with the presence and absence of methyl methacrylate (MMA) at 10?pphr. It was found that the gamma irradiation of latex blend with the presence of MMA could help increase further the tensile value. Composition of blending at a specific ratio and gamma irradiation at a specific dose has led to a significant improvement in the mechanical properties of the latex blend. The formation of grafting in the latex blend was characterized by Fourier transform infrared spectra (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy confirmed that MMA could be grafted onto blended latex effectively under appropriate irradiation conditions. Two new peaks at 1731 and 1149?cm^?1 were observed after irradiation, indicating the presence of an ester group from poly(methyl methacrylate) (PMMA), which was grafted onto rubber chains. This finding was proved by the presence of new T_g in DSC analysis. The increase in new T_g indicates the movement of grafting chains, which are tightly bound onto rubber chains.     

Tetramethylpolyarylate-polyarylate block copolymer: Synthesis and miscibility with polyarylate and poly(styrene-co-acrylonitrile)

Abstract

Tetramethylpolyarylate-polyarylate (TMPAr-PAr) block copolymers of various block lengths were synthesized by the coupling reaction of hydroxy-terminated TMPAr and hydroxy-terminated PAr using triphosgene. The phase behavior of these block copolymers are discussed based on the thermal properties observed by differential scanning calorimetry (DSC). The thermal properties of binary blends of these block copolymers with PAr homopolymer or poly(styrene-co-acrylonitrile) whose acrylonitrile content is 9.5 wt% (SAN 10) were observed by DSC. The compatibilizing effect of the microphase-separated TMPAr-PAr block copolymer in PAr/SAN 10 blends was observed from thermal properties and morphology.     

Dielectric spectra of LiTFSI-doped chitosan/PEO blends

Solid-polymer-blend electrolyte consisting of chitosan and polyethylene oxide (PEO) in a 1:1 weight ratio and doped with lithium trifluoromethanesulfonimide (LiTFSI) salt was prepared by solution cast technique. The highest conducting film with conductivity value of 1.40 × 10^-6 S cm⁻¹ at room temperature consists of 30 wt% LiTFSI. The temperature dependence for the highest conducting film obeyed Arrhenius relationship. From loss tangent–frequency plots at different temperatures, the frequency f _max at which the plot is a maximum was obtained. From this, ln f _max vs 10³/T was plotted. The activation energy value obtained from the log σ vs 10³/T plot and ln f _max vs 10³/T plot is about the same, suggesting that the processes of conductivity and relaxation for the charge carriers are the same. This paper was presented at the International Conference on Solid State Science and Technology 2006, Kuala Terengganu, Malaysia, Sept. 4–6, 2006.     

Ag2O nanoparticle clusters coated with porous gelatin-g-PMMA copolymer

Herein a special nanoparticle cluster coated with a porous copolymer is designed and prepared. At first, Ag₂O nanoparticles (secondary particles) were fabricated in gelatin solution by a facile chemical approach. Then these nanoparticles were entrapped in a copolymerization system containing gelatin, methyl methacrylate (MMA), an initiator, and using water as a solvent. The nanoparticle clusters coated with porous gelatin-g-PMMA copolymer (Ag₂O/gelatin-g-PMMA) were prepared by grafting methyl methacrylate onto gelatin, followed by coating solidification. One significant feature for our approach is that every Ag₂O aggregated cluster has been coated with porous gelatin-g-PMMA copolymer film in a unique way, and the Ag₂O nanoparticle could penetrate and escape from the coating freely in water by ultrasonication. As a result, this study provides a new approach to prepare monodispersed nanoparticles by ordered porous copolymers with controlled releasing.     

Investigation of Cell Structure and Expansion Ratio of Microcellular Polypropylene Nanohomocomposites Prepared by a Solid-State Process

Microcellular poly(propylene-ethylene) random copolymer (r-PP-PE)/nanoclay (nanocomposite) and r-PP-PE/nanoclay/polypropylene fibers (nanohomocomposite) were autoclave-foamed via a solid-state microcellular foaming process using supercritical N₂ as a foaming agent. Polypropylene grafted with maleic anhydride (PP-g-MA) was used as a compatibilizer. Amount of PP-g-MA to nanoclay was 3:1. This study investigated the effects of clay content and the presence of polypropylene fiber on the expansion ratio and cell morphology of the samples. The results indicated that nanoclay increased the expansion ratio of the samples, but the expansion ratio for nanohomocomposites was slightly lower than the nanocomposites. In addition, scanning electron microscopy (SEM) observation showed that the nanoclay decreased the cell size and increased the cell density, except for the nanocomposite with the highest nanoclay content, 3 wt%, which had larger cell size compared to the samples with 1.5 wt% nanoclay and less. On the other hand, the simultaneous presence of nanoclay and polypropylene fibers synergistically increased the cell nucleation effect; thus there was a dramatic increase in cell density. The Differential scanning calorimetry (DSC) analysis showed that the microcellular foaming process decreased the crystallinity of both types of samples.     

Glass Transition Behavior and Dynamic Fragility of PMMA-SAN Miscible Blend-Clay Nanocomposites

An investigation of the segmental dynamics and glass transition behavior of a miscible polymer blend composed of poly(methyl methacrylate) (PMMA) and poly(styrene-ran-acrylonitrile) (SAN) and its melt intercalated nanocomposite by dynamic mechanical analysis is presented. The principle goal was to address the effect of intercalation on local molecular structure and dynamics. The results showed that the intercalation of polymer chains in the galleries of organoclay (Cloisite 30B) led to a lower temperature dependence of the relaxation time (fragility) and activation energy of α-relaxation. Moreover, calculation of the distribution of the segmental dispersion showed a narrower dispersion in the glass transition region so that the Kohlrausch-Williams-Watts (KWW) distribution parameter (β_KWW) increased from 0.21 for neat PMMA to 0.34 for the 50/50 PMMA/SAN blend nanocomposite containing 3 wt% organoclay. Furthermore, the relaxation behavior of the blends showed a negative deviation from mixture law predictions based on the responses of the neat PMMA and SAN. These behaviors were attributed to the lack of specific interactions between the blend components (PMMA, SAN, and nanoclay layers) and the less cooperative behavior, i.e., less constraint for segmental relaxation, of the intercalated chains.     

Rheological Behaviors of Polypropylene/Poly(1-butene) Blends

The rheological behaviors of polypropylene (PP)/poly(1-butene) (PB) blends with homo-polypropylene (PP₁) or impact polypropylene (PP₂), a poly(propylene-co-ethylene) as the PP component were studied. With increasing of PB resin content for both PP/PB blends, the blends showed higher G'(ω), G''(ω) and η*(ω) at low frequencies but lower values at high frequencies which implied that the processability was improved. A two-phase morphology was observed through the various rheological responses, including G'(ω)-ω terminal region curves, Cole-Cole plots and the weighted relaxation spectra with the PB contents up to 40?wt%. With the same PB content, the rheological parameters of the PP₂/PB blends were quite different from those of the PP₁/PB, which can be attributed to the stronger interaction between PB chains and the ethylene-co-propylene copolymer in PP₂. The impact strength of the PP₂/PB blends was improved dramatically over that of the PP₁/PB. The more significant toughening effect for the PP₂/PB blends can be attributed to the special responses of its rheological behaviors.     

Mechanical and Morphological Properties and Deformation Mechanisms of Acrylonitrile-Butadiene-Styrene/Poly(ϵ-Caprolactone) Blends with Varied Matrix Composition

Acrylonitrile-butadiene-styrene and poly(?-caprolactone) blends (ABS/PCL) were prepared by mixing styrene-co-acrylonitrile (SAN), polybutadiene-g-SAN (PB-g-SAN), and PCL with varied SAN and PCL composition. PCL is miscible with SAN and can improve the matrix toughness. The impact strength and elongation at break of the ABS/PCL blends increased with the PCL content. When the PCL content was lower than 20 wt%, the improvement of impact strength for the blends was not obvious. A significant increase of impact strength took place when the PCL content was between 20 and 25 wt%. When PCL content was more than 20 wt%, the impact strength was higher than 800 J/m which shows the super toughness. The addition of PCL improved the dispersed phase morphology of PB-g-SAN in the matrix and the interfacial adhesion increased. Deformation observations showed that, when the PCL content was lower than 20 wt%, crazing was the major deformation mode. When the PCL content was 20 wt%, crazing and slight shear yielding could be found. When the PCL content was more than 20 wt%, cavitation of rubber particles and shear yielding of the matrix were the major deformation modes. The cause of the change of the deformation mode lies in the varied matrix composition which modifies the crazing and yielding stresses of the matrix and the final fracture mode and impact toughness.     

Preparation of magnetic poly(methylmethacrylate–divinylbenzene–glycidylmethacrylate) microspheres by spraying suspension polymerization and their use for protein adsorption

Moderately uniform magnetic poly(methylmethacrylate–divinylbenzene–glycidylmethacrylate) microspheres (poly(MMA–DVB–GMA) microspheres) were prepared by spraying suspension copolymerization of methyl methacrylate, divinylbenzene and glycidyl methacrylate in the presence of Fe₃O₄ magnetic fluid. A protein adsorption assay indicated that these magnetic microspheres could significantly improve the capacity of protein adsorption.     

Effect of doping MnO2 on magnetic properties for M-type barium ferrite

The crystalline structure and magnetic properties of M-type barium ferrite doped with small amounts of MnO₂ (0, 0.25, 0.5, 0.75, 1.0, 1.5, and 2.0 wt%, respectively) have been investigated by means of XRD, SEM and VSM. The results show that the crystalline structures of barium ferrite are still M-type hexagonal structure and Mn ions are distributed homogeneously in both the grains and the grain boundaries. The saturation magnetization and magnetocrystalline anisotropy constants both reach the highest values when x=0.75 wt%. The displacement of Fe ions from 4f₁ to 2b site is mainly responsible for the appearance of the maximum values.     

Optical measurement of KB/KS divergence in nematics

A direct optical analysis of the divergence of the elastic constant ratio K_B/K_S in a nematic material near the T_AN transition temperature is presented. The results are in excellent agreement with what obtained from more complicated techniques. The method used exhibits a large number of advantage with respect to the conventional ones.