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As a promising structural material, various tough hydrogels have been developed in recent years by incorporating different kinds of noncovalent bonds as the energy-dissipating segments. Among these systems, it is challenging to use hydrogen bonds due to their instability in aqueous environment. Here we report a tough hydrogel of poly(1-vinylimidazole-co-acrylic acid) (P(VI-co-AAc)) reinforced by the...
Nanoparticles reinforcement of polymers has been of great interest to researchers for the better part of a century. However, researchers are in confusion in describing the role of filler network. Herein we report a framework to solve both reinforcement and dissipation of nanocomposites with respect to strain amplification effect of dynamically retarded bulk polymer phase and jamming of nanoparticles...
Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared...
Nanoparticle reinforcement at low and moderately high loadings has been assigned to the hydrodynamic and networking effects, respectively while the conclusions are ambiguous without specifying the “frequency”-dependent polymer dynamics. Herein a unique time-concentration superpositioning (TCS) principle is disclosed for accounting for the hydrodynamic-to-jamming regime transition associated with the...
Filling significantly reinforces rubbers and introduces rheological nonlinearity, which is usually ascribed to filler networking and destructuring effects while conceptual conflicts still exist. Herein nonlinear rheology of compounds of fumed silica filled emulsion-polymerized styrene butadiene rubber is investigated with respect to silica type (hydrophilic and hydrophobic) and loading. The results...
A new strategy for fabricating polypropylene alloy with good low-temperature toughness was reported. Glass transition temperature (Tg) of rubber phase in polypropylene/ethylene-propylene rubber/poly(styrene-b-ethylene/propylene) diblock copolymer (PP/EPR/SEP) blend was continuously reduced through strengthening the interfacial tensile force on rubber phase by using the concept of mismatched thermal...
Filling can cause polymer melt to undergo a so-called fluid-to-solid transition usually assigned to filler networking effect and heterogeneously retarded polymer dynamics while theories developed nowadays could not account for the several important aspects involving in the reinforcement and dissipation of the composites including the influence of molecular weight of the matrix. Herein linear dynamic...
Supramolecular polymeric hydrogels, combining the responsiveness of noncovalent interactions and good mechanical properties of polymers, have received increasing attentions due to their high strength, multi-responses to stimuli, and good processability. In this article, we develop transparent physical hydrogels by simply casting and reswelling the films of copolymers synthesized by polymerization...
The rapid developments of tough hydrogels have promoted the applications of this kind of soft materials in loading bearing systems. However, tough gels usually have poor processibility, which is crucial for the construction of complex structures with gels. In this paper, we demonstrate the processing of tough polyion complex (PIC) hydrogels by simple compression moulding or extruding, which relies...
Toughening with little rigidity loss was achieved by adding high density polyethylene (HDPE) into polypropylene/ethylene-propylene random copolymer (PP/EPR) blends to fabricate a series of PP/EPR/HDPE ternary blends with core–shell dispersed particles. Morphology observations revealed that the addition of HDPE leads to the appearance of core–shell dispersed particles in PP matrix, i.e., HDPE core...
According to a two-step preparation technique consisting of temperature-gradient extraction fractionation (TGEF) and subsequent solution-mixing, a series of polypropylene/ethylene-propylene random copolymer/ethylene-propylene block copolymer (HPP/EPR/EbP) blends containing multilayered core–shell dispersed particle with bridges were prepared to explore the influences of dispersed phase on crystallization...
It is well-known that introduction of charged groups to poly(N-isopropylacrylamide) (PNIPAM) raises its phase transition temperature. However, the influence of charged groups on structural evolution and dehydration dynamics of weakly charged PNIPAM during phase transition still lacks systematic investigation. In the current study, armed with rheometer and two-dimensional Fourier transform infrared...
A series of dangling chain based-polyurethane/poly(methyl methacrylate) (DPU/PMMA) filled with exfoliated layered double hydroxides (LDH) were synthesized by methyl methacrylate in-situ intercalative polymerization. The dangling chains were introduced by using vegetable oils as chain extender. The effect of dangling chain and the contents of LDH on the molecular dynamics of DPU/PMMA was investigated...
Shell-crosslinked core–shell nanoparticles (SCCSN) of 63–104 nm in diameter and containing 79.1 wt% crosslinked polystyrene (PS) shell of 16.5–37.0 nm in thickness were prepared by miniemulsion polymerization of styrene in the presence of silane modified nanosilica. The PS shell was crosslinked using divinyl benzene in order to anchor the shell on the nanoparticle surface, to segregate the silica...
Dicumy peroxide (DCP) modification of low density polyethylene (LDPE) below gel point (GP) produces modified LDPE (mLDPE) with wide molecular weight distributions while the random crosslinking beyond GP yields crosslinked LDPE (XLPE). Molecular weight distributions of mLDPE below GP and the sol-fractions of XLPE above GP were investigated. The sol-fractions in XLPE were extracted to prepare XLPE gels...
Poly(methyl methacrylate)/poly(styrene-co-maleic anhydride) (PMMA/SMA) blends with various compositions were prepared through solution casting and melt blending. Two preparation routes, solution casting and melt blending, were used to achieve different degrees of molecular entanglement in the samples with solution casting giving rise to a lower degree of entanglement. Therefore, the effect of molecular...
The linear dynamic rheology for a series of filled polymer melts is investigated to take account for the respective contributions of the bulky polymer phase away from the filler inclusions and the “filler phase” composed of filler particles coated with polymer layer. Time-concentration superposition principles are introduced to the linear viscoelasticities of both the bulky polymer phase and the “filler...
The phase structure evolution of high impact polypropylene copolymer (IPC) during molten-state annealing and its influence on crystallization behaviour were studied. An entirely different architecture of the IPC melt was observed after being annealed, and this architecture resulted in variations of the crystallization behaviour. In addition, it was found that the core-shell structure of the dispersed...
A two phase model proposed for accounting for linear viscoelasticity of polymer nanocomposite melts [14] is applied to rubbers filled with nanoclay and conventional fillers (carbon black and silica) to probe mechanisms of the fluid- and the solid-like behaviors beyond the terminal flow region. This model shows strong applicability in linear rheology beyond terminal region for a variation of filled...
The morphology of impact polypropylene copolymer (IPC) was studied through scanning electron microscope (SEM) and transmission electron microscope (TEM) observation, and a modified dispersed phase model of IPC with core-shell structure was proposed. Through fractionation of IPC, the glass transitions of the ethylene–propylene random copolymer (EPR) fraction, ethylene–propylene block copolymer (EbP)...
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