Design of miscible polyolefin copolymer blends

Theoretical guidelines are established for designing miscible blends of amorphous polyolefin copolymers. On the basis of calculations for an athermal and incompressible model of copolymer melts, limits are placed on the compositions and structural differences between blend components that are consistent with thermodynamic stability of a single liquid phase. Specific cases analyzed include binary blends of random copolymers containing short branches and blends of graft polymers with long flexible branches, either periodically or randomly placed. The predictions are shown to be in good agreement with recent experimental studies of miscibility in model polyolefin copolymer blends. © 1995 John Wiley & Sons, Inc.     

Photoinitiated polymerization of acrylate,methacrylate, and vinyl ether end‐functional polyisobutylene macromonomers

Polyisobutylene‐based UV cured networks potentially useful as sealants were synthesized by photopolymerization of well‐defined polyisobutylene methacrylate (PIB‐MA), acrylate (PIB‐A) and vinyl ether (PIB‐VE) di‐ and trifunctional macromonomers. The kinetics of photocrosslinking were measured using an optical pyrometer apparatus and optimized with respect to different experimental parameters. PIB‐MA/A macromonomers displayed enhanced reactivity in radical photopolymerization in the presence of a bis(acylphosphine) oxide photoinitator. PIB‐VE macromonomers exhibited a high rates of photopolymerization with (4‐n‐octyloxyphenyl)phenyliodonium hexafluroantimonate as the photoinitiator. The rates as well as the ultimate monomer conversions were increased by increasing the irradiation light intensity. The inherent induction period associated with oxygen inhibition in the photopolymerization of PIB‐MA was significantly reduced by optimizing the choice of photoinitiator. A detailed investigation of the concentration of MA/A/VE end groups revealed the presence of a prominent saturation effect in the photopolymerization of PIB‐A, which was absent with PIB‐MA and PIB‐VE. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

The influence of PEG macromonomers on the size and properties of thermosensitive aqueous microgels

We describe the preparation and thermal response of aqueous microgels based on poly(N-vinyl caprolactam) containing grafted poly(ethylene glycol) (PEG) chains. These microgels were synthesized by free radical copolymerization of vinyl caprolactam and acetoacetoxyethyl methacrylate in the presence of methoxy-capped poly(ethylene glycol)methacrylate macromonomers. We show that variation of the amount of PEG macromonomer or the length of the PEG chain provides effective control of the microgel diameter in the range 60–220 nm. The presence of the grafted PEG chains improves the colloidal stability of the microgels. The incorporation of the PEG macromonomers into microgel structure decreases the swelling degree and induces a shift of the volume phase transition to higher temperatures. This paper is dedicated to Professor Haruma Kawaguchi in honor of his many contributions to the field of polymer particle synthesis and applications.     

Compatibility Studies on Dehydrated Castor Oil Epoxy Blend with Poly(Methacrylic Acid)

Blending is a useful technique to improve upon the physico‐mechanical properties of the polymers. Synergies of the properties of the two polymers occur best when they are miscible or compatible with each other. Vegetable oil epoxy can be used for blending with polymers to improve upon their physical and mechanical properties. Poly(methacrylic acid) (PMAA) is a hard, brittle and water sensitive material. Dehydrated castor oil epoxy (DCOE), a product from a sustainable resource, has been chosen to improve upon the physical and mechanical properties of PMAA through solution blending. Blends of DCOE/PMAA were prepared in the weight ratios 80/20, 60/40 and 20/80 through a solution method by mixing in dimethyl sulphoxide. In the first instance, the miscibility of the two components was investigated using the techniques of viscosity and ultrasonic measurements. The study revealed that the two components showed semicompatibility/semimiscibility in solution. The compatibility in the solid phase was examined by differential scanning calorimetry and scanning electron microscopy which revealed that DCOE–PMAA pair were incompatible in solid phase.     

The bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes for polyethylene macromonomers

The synthesis of long‐chain branched polyethylene includes the generation of vinyl‐terminated polyethylene macromonomers and the copolymerization of these macromonomers with ethylene. Four new bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes 1a–b, 2a–b were prepared and showed high activities for ethylene homopolymerization upon the activation of methylaluminoxane. The steric bulk of bridged substituent has a profound effect on the catalytic activity as well as on the molecular weight of resulting polyethylene. Complex 1b showed the highest activity of up to 5.32 × 10⁶ g PE/(mol Zr h) for ethylene homopolymerization at 70 °C, which was higher than that of Cp₂ZrCl₂. The polyethylenes produced with complexes 1a–d/MAO are mostly vinyl‐terminated, possess low molecular weight and fit as macromonomers. The (p‐MePh)₂C‐bridged cyclopentadienyl indenyl zirconocene complex 1a could produce polyethylene macromonomer with selectivity for the vinyl‐terminal as high as 94.9%. Copyright © 2010 John Wiley & Sons, Ltd.     

Gradient graft copolymers derived from PEO‐based macromonomers

Atom transfer radical polymerization (ATRP) of two poly(ethylene oxide) (PEO) macromonomers, with different polymerization degrees (DP_n) and different end groups, was conducted in solution via the grafting through method. Selection of a PEO methacrylate with a methyl end‐group (PEOMeMA, DP_PEO = 23) and a PEO acrylate end‐capped by a phenyl ring (PEOPhA, DP_PEO = 4) for the copolymerization led to a spontaneous gradient of PEO grafts along the copolymer backbone. Such a composition was formed because of significantly different reactivities of the two PEO macromonomers. The resulting copolymer has PEOMeMA at one end of the polymer chain, gradually changing through hetero‐sequences of PEOPhA at the other chain end. An increase in the initial feed ratio of PEO acrylate reduced the rate of change in the shape of the gradient. Amorphous–crystalline structure in the copolymers was demonstrated by DSC and WAXS. The mechanical measurements of copolymers consisting of an amorphous PEOPhA and crystallizable PEOMeMA segments indicated elastomeric properties in the range of a soft rubber (G′ ～ 10⁴ Pa, G′ ? G″). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1347–1356, 2006     

Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

Epoxy resins are widely used in coatings, adhesives and polymer composites, but the applications of cured epoxy resins are often restricted by their poor toughness. HBP can be used as toughener to improve the toughness of epoxy resins due to its high-dens…     

聚酯热熔胶增韧环氧树脂

利用扫描电子显微镜研究了聚酯热熔胶PE30增韧环氧树脂的微观相结构;利用DSC、DMA和TGA研究了聚酯热熔胶PE30对环氧树脂耐热性能的影响;测试了环氧树脂的冲击强度、弯曲强度和断裂韧性,考察了聚酯热熔胶PE30对环氧树脂力学性能的影响。结果表明,聚酯热熔胶PE30的最佳质量分数为15%,在固化过程中环氧体系发生诱导相分离,相结构由单相到连续相再到反转相;断裂韧性和冲击强度分别提高了127%和250%;弯曲强度和弯曲模量分别降低27%和44%;而体系玻璃化转变温度与起始热失重温度下降约1.5%,损耗峰温度下降约2.5%,说明聚酯热熔胶PE30可以在很大程度上提高环氧树脂的韧性,同时保持其耐热性能基本不变。     

Phase behavior and some calorimetric and physical properties of diurethanes from perfluoropolyether macromonomers

Density and calorimetric measurements have been carried out on copolymeric perfluoropolyethers of molecular weight ranging between 500 and 4700, terminated at both chain ends either with  CH₂OH or ethylurethane groups. Samples of the second series are models for perfluoropolyethers based polyurethanes. Density measurements point out that the terminal alcoholic group brings about a negative excess volume, which increases with decreasing the molecular weight; a lower excess volume is found for urethane‐terminated molecules. Calorimetric traces, T_g, and Δc_p at T_g show that alcoholic‐terminated molecules are amorphous and one phase systems, while urethane‐terminated compounds are crystalline; phase separation is observed for this last series when the molecular weight of the fluorinated segment is larger than 1000. The trend of T_g with molecular weight is discussed for one‐ and two‐phase systems in the light of current theories for the glass transition. The decrease of the melting point with increasing the molecular weight for the urethane series can be described by the Flory equation for random copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1609–1622, 1999     

Epoxy/poly(4-vinylphenol) blends crosslinked by imidazole initiation

Poly(4-vinylphenol) (PVPh) was used as thermoplastic modifier of epoxy resins. Binary epoxy/PVPh mixtures with high thermoplastic content rise high glass transition temperatures (T _g) after heating, due to the epoxy-phenol reaction. Blends with low PVPh percentages reach high T _g if 2-methylimidazole is added, which catalyses epoxy homopolymerisation and epoxy-phenol reaction. The cured blends do not present phase separation although the network structure depends on the epoxy/phenol ratio. At low PVPh percentage the main crosslinking reaction is epoxy-epoxy but, when the thermoplastic content increases, the epoxy-phenol reaction prevails, causing an important T _g increase and becoming less brittle.     

Synthesis and polymerization of first‐generation dendritic methacrylate macromonomers

First‐generation dendritic macromonomers with a methacryloyl end group on one side, long alkyl chains on the other side, and a biuret system with two urethane groups in the core have been synthesized. The synthesis comprises three steps with hexamethylene diisocyanate uretdione as the starting material. The branching points were introduced via biuret groups and the prepared macromonomers were polymerized by free and controlled radical polymerization. Depending on the reaction conditions linear dendronized polymers as well as branched dendronized polymers and microgels with long alkyl chains were obtained. Scanning force microscopy was used to visualize high molecular weight molecules spincoated on highly oriented pyrolytic graphite. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 614–628, 2007     

核／壳结构增韧剂对环氧树脂的抗冲改性

核／壳结构增韧剂对环氧树脂的抗冲改性张明耀，张会轩，杨海东，冯之榴（吉林工学院化学工程系长春１３００１２）（中国科学院长春应用化学研究所长春）关键词核／壳结构，增韧剂，环氧树脂，共混核／壳结构增韧剂是用分步乳液聚合技术制造的一种复合乳胶粒子，其核为橡...     

Mesomorphic phase formation of poly (macromonomer)s of polystyrene macromonomers

The liquid crystalline phase formation of poly(macromonomer)s associated with the specific multibranched architecture of high branch density was investigated. The poly(macromonomer)s were prepared by radical chain polymerizations of ω‐methacryloyloxyethyl polystyrene macromonomers. It was confirmed that the mesomorphic phase formation depended on the branching architecture, where sufficient length of the branch chains as well as the backbone chain is crucial for the formation of the mesomorphic phase. Formation of the optically anisotropic mesophase also depended on the nature of solvent. The mesophase was observed in the cast films prepared from p‐xylene, toluene, tetrahydrofuran, carbon disulfide and chloroform but not observed for cyclohexane. The effects of the branched structure and the solvent nature were explained by repulsive interaction between the polystyrene branch chains of high branch density. The repulsive interaction increases the chain stiffness of the central backbone and also prevents the interpenetration of the polystyrene branches of different molecules in solution, which allow poly(macromonomer) molecules to arrange with the orientational order. Copyright © 2000 John Wiley & Sons, Ltd.     

Formation and morphology of cellulose acetate butyrate (CAB)/polyolefin and CAB/polyester in situ microfibrillar and lamellar hybrid blends

Cellulose acetate butyrate (CAB)/iPP (isotactic polypropylene), CAB/HDPE (high density polyethylene), CAB/PET (poly ethylene terephthalate), CAB/PTT (poly trimethylene terephthalate), CAB/PBT (poly butylenes terephthalate) and CAB/IPET-PEG (poly(ethylene terephthalate-co-isophthalate)-poly(ethylene glycol)) in situ microfibrillar and lamellar hybrid blends at a weight ratio of 80/20 were prepared by melt extrusion. Microfibrillar and lamellar hybrid morphologies of CAB/polyolefin and CAB/polyester blends under different force fields were investigated. The formation process of in situ microfibrillar and lamellar hybrid blends were analyzed and proposed.     

Kinetics study of oil sorption with open‐cell polypropylene/polyolefin elastomer blend foams prepared via continuous extrusion foaming

The objective of the present work was to study the sorption kinetics of open‐cell polypropylene/polyolefin elastomer (PP/POE) blend foams. First, open‐cell PP/POE foams of different cell structures were prepared by controlling the foaming temperature via a continuous extrusion foaming process. Second, the effect of the cell structures on the sorption process, rate, and capacity was studied. Pseudo‐first order and pseudo‐second order models were applied to study the sorption kinetics of the PP/POE foams for cyclohexane. Third, the sorption rate and sorption capacity by both volume and weight of the PP/POE foam for different oils and solvents were studied to show how the intrinsic properties of the testing oils and solvents affected the sorption performance. The results showed that the sorption with the PP/POE foams followed the pseudo‐second order kinetics model. Both the cell structures of the foams and the intrinsic properties of the testing oils and solvents affected the sorption performance. For the same testing oil, a higher open‐cell content in the foam was favorable for a higher sorption rate, and a higher void fraction was favorable for a higher sorption capacity. For the same foam, a lower viscosity of the testing oil was favorable for a higher sorption rate. The sorption capacity by volume was closely related to the viscosity of the testing oil, while both the viscosity and the density of the testing oil determined the sorption capacity by weight.     

Amphiphilic comb-shaped polymers from poly(ethylene glycol) macromonomers

Comb-shaped amphiphilic graft copolymers composed of hydrophobic backbones and hydrophilic side chains were prepared by radical copolymerization of poly(ethylene glycol) monomethacrylate macromonomers, and methacrylate and acrylate comonomers in toluene. The copolymerizations were very sensitive to the reaction conditions, and insoluble cross-linked gels were easily formed. The yields of soluble copolymers were affected by the initiator concentration, the macromonomer concentration, and the choice of chain transfer agents and comonomers. Solubilities of the copolymers in water or methanol were found to depend on the sizes and the numbers of the PEG side chains. The copolymers showed surface activity with CMC:s in the order of 0.1–1.5 g/L and surface tensions of 36–56 dyn/cm. When tested as emulsifiers most of the copolymers gave oil-in-water type emulsions at room temperature. Polymers carrying MPEG 2000 side chains were crystalline with melting points of 38–44°C, while those based on PEG 400 and 1000 were mostly amorphous with glass transition temperatures between -55 and -60°C. © 1992 John Wiley & Sons, Inc.     

Polyolefin,olefin copolymers and polyolefin polyblend nanocomposites

This paper reviews recent studies done in academia or industrial laboratories on polymer nanocomposites based on various type of polyolefins like homopolymers, copolymers and polyblends reinforced with various mineral (montmorillonite, bentonite, closite, laponite, layered double hydroxide, etc.) carbon based (graphite, carbon nanotubes, carbon nanofibers, exfoliated graphite, graphene, carbon black, etc.) nanofillers. The review covers their preparation, their mechanical, thermal, flammability, gas barrier capability, electrical, dielectrical, antibacterial characteristics and their potential applications like low weight structural materials, part of optical devices, thermal interface materials, electric and electromagnetic components, absorption, antibacterial materials, etc.     

环氧树脂/聚碳酸酯固化共混物的结构及性能

相结构;酯交换反应;力学性能;环氧树脂/聚碳酸酯固化共混物的结构及性能     

降解型环氧树脂*

设计与合成带有可降解官能团的环氧树脂是热固性树脂回收领域的一个重要课题。本文首先简要概括了传统回收环氧树脂的方法并指出其缺点,然后分别对国内外热降解型、光降解型、生物降解型环氧树脂的降解特性、环氧固化物的降解条件和降解机理予以重点解释和举例介绍。最后,指出了降解型环氧树脂存在的问题并对将来的发展前景进行了展望。