Jia De-min

Preparation and Properties of Polypropylene/Clay Nanocomposites using an Organoclay Modified through Solid State Method

In this article, the organically modified clay (organoclay) was prepared by treating Na-montmorillonite with alkylammonium ions through a solid state method. Polypropylene (PP)/organoclay nanocomposites were prepared by melt intercalation. X-Ray Diffraction (XRD) and Transmission Election Microscopy (TEM) indicated that PP chains could intercalate into the gallery of organically modified clay to form the exfoliated PP/organoclay nanocomposites. The crystallization peak temperature of PP/organoclay nanocomposites was higher than that of neat PP by Differential Scanning Calorimetry (DSC). According to XRD, the addition of organoclay did not change the crystal structure of PP. Thermalgravimetric analysis showed that the thermal decomposition temperature of PP/organoclay nanocomposite was higher than that of PP. A mechanical properties test indicated that the impact strength of PP/organoclay nanocomposites were better than that of neat PP when the organoclay content was below 7wt%.

Influence of Organoclay Prepared by Solid State Method on the Morphology and Properties of Polyvinyl Chloride/Organoclay Nanocomposites

In this study, organically modified clay (organoclay) is prepared by treating Na+ montmorillonite with alkylammonium ions and silane coupling agent KH-560 through a solid phase method. Polyvinyl chloride (PVC)/ organoclay nanocomposites are prepared by melt intercalation. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate that PVC chains can intercalate into the gallery of the organoclay to form exfoliated PVC/ organoclay nanocomposites. The glass transition temperatures (T g) of PVC/ organoclay nanocomposites are studied with differential scanning calorimetry (DSC), and the result shows the T g of PVC/organoclay nanocomposites are higher than that of neat PVC. Thermogravimetric analysis shows that organoclay can slow down the speed of thermal decomposition and tend to increase the on-set thermal decomposition temperature of the PVC. Mechanical properties test indicates that when the organoclay content is below 7 phr, the impact strength of PVC/organoclay nanocomposites are better than that of neat PVC.

Study on the Crystallization Properties of Polypropylene/Montmorillonite Composites

The crystalline size of polypropylene (PP) filled with montmorillonite (MMT) was studied by X-ray diffraction (XRD). The isothermal crystallization behavior of polypropylene was studied by means of differential scanning calorimetry (DSC). The Avrami equation was used to describe the isothermal crystalline kinetics of PP/MMT composites. The result showed that the addition of MMT decreased the crystalline size L hkl of the polymer. MMT was used as nucleating agent during isothermal crystallization process of polypropylene. The addition of montmorillonite decreased the crystallization time of the polypropylene and the melt point was raised. The value of Avrami exponent n was related with the crystallization temperature. The value of Avrami pre-index factor k of PP/MMT composite was decreased with increasing crystallization temperature. The value of half crystallization time t 1/2 of PP/MMT composite was less than that of PP at a given crystallization temperature, signifying that montmorillonite acted as nucleating agent, accelerated the overall crystallization process.

Preparation and mechanical properties of solid-phase grafting nanocomposites of PVC/graft copolymers/MMT

In order to improve the mechanical properties of PVC, by solid-phase grafting reaction, grafting on and nano-modifying the PVC process synchronously, acrylic monomers not only graft on PVC, but also are intercalated into the layers of MMT in the heating process. Blending PVC and the MMT-PVC grafting copolymers, we can get nanocomposites of PVC/grafters/MMT, and the mechanical performance of the material is improved.

Effect of Interfacial Modifiers on Physical Properties and Flammability Properties of PE/Wood Composites

The ternary-monomer graft copolymers of polyethylene (GPE) were used as interfacial modifiers for recycled polyethylene (rPE)/wood flour (WF) composites. How the interfacial modifiers and WF processing methods affected the mechanical properties, thermal stability and flammability properties of the composites were investigated. Results show that the steam-braising on WF could increase the mechanical properties of the composites. The interfacial modifiers were excellent compatilizers for the rPE/WF composites that significantly increased the mechanical properties of the composites. Wood flour acted as charring agent during the combustion of the composites to improve the flame retardancy of PE/wood flour composites. Due to the improved interface compatibility between rPE and WF by GPE, the rPE/WF composites maintained excellent mechanical properties and flame retardancy even at higher filler content.

Influence of Adjustable Grafted Side Chains on the Non-isothermal Crystallisation of a Ternary-monomer Solid Phase Graft Copolymer of Polypropylene

A solid phase graft copolymer with an adjustable structure was prepared by grafting maleic anhydride, methyl methacrylate and butyl acrylate onto polypropylene (PP). How the grafted side chains affected the crystallisation of the graft copolymer was studied by differential scanning calorimetry and polarised optical micrographs. Results show that the grafted side chains not only promoted heterogeneous nucleation but also hindered the whole crystal growth of the copolymers. The Jeziorny method and Mo method were successful in describing the non-isothermal crystallisation kinetics. The Jeziorny method showed that the Avrami exponent ranged from 2 to 3, indicating that the crystal tended to grow in a three-dimensional mode. The Mo method showed that the graft copolymer (known here as PPTM) needed a lower crystallisation rate than PP to attain the same crystallinity at unit time, due to the hetero-nucleation of the grafted side chains. Meanwhile, the hetero-nucleation of the grafted side chains caused a decrease in the crystallisation half-time and in the spherulite size of PPTM. Hindrance of the grafted side chains was shown by the incomplete crystallisation images and by the increase in the non-isothermal crystallisation activation energy of PPTM.

Mechanical and thermal properties of FPM/PHACM/ACM blends

The bisphenol AF/benzyltriphenylphosphonium chloride (BPP) vulcanization system is the most commonly used fluoroelastomer (FPM) vulcanization system. In this article, polyphenol hydroxy acrylic rubber (PHACM) was prepared through a two-step reaction: grafting polymerization and condensation. The properties of FPM/PHACM/acrylic rubber (ACM) blends including vulcanization properties, mechanical properties, aging properties, oil resistance and thermal properties were studied. The results of vulcanization properties show that under the bisphenol AF/BPP vulcanization system, the FPM can achieve covulcanization with PHACM without adding bisphenol AF and get longer scorch time than that of FPM with the same level of bisphenol AF, which means that FPM/PHACM/ACM blends have better processability and curing security. Furthermore, the blends show better mechanical properties and thermal stability. The results of differential scanning calorimeteric analysis show that the FPM and PHACM achieve co-cross-linking and have good compatibility. The glass transition temperature (T g) of the blends has been reduced to −18.57°C, which is 8.33°C lower than that of pure FPM, when the content of blends is equal to 100/100. The scanning electron microscopy shows that PHACM can improve interfacial adhesion between the FPM and ACM.

In situ Preparation of Epoxy-Based Conductive Nanocomposites Containing Nanosilver-Decorated Carbon Nanotubes

Nanosilver-decorated carbon nanotubes(CNTs)were prepared by introducing CNTs and silver acetate into an epoxy-imidazole curing system and simultaneous in situ thermal degradation of an Ag-imidazole complex.Differential scanning calorimetry(DSC)results indicated that modified CNTs played a certain role in promoting the curing of the epoxy.The structure of the silver acetate-imidazole complex was characterized by X-ray diffraction(XRD).The size of the nano-silver particles resulting from degradation of the Ag-imidzole complex was between 21 and 24 nm,and between 11 and 13 nm when the Ag-imidzole complex was added to the epoxy matrix.When silver flakes with a mass fraction of 80%was added to the composites,the volume resistivity of the nanosilver-decorated CNTs/epoxy conductive composite was as low as 9×10 -5 Ω·cm.The optimum conductivity and shear strength were achieved when the ratio of nanosilver and CNTs was 80:20(mass ratio).Scanning electron microscopy(SEM)revealed the structural morphology of the composite.

Crystallization Behavior of PP in Composites with EPDM and a Surface Modified Nano-Calcium Carbonate

A modified nano-CaCO3 (RCCR) was prepared by mixing the stearic acid treated nano-CaCO3 (CCR) with organic agent containing —OH, —COOH, and C=C groups and it was then melt compounded with polypropylene PP and Ethylene-propylene-diene mischpolymer (EPDM) to prepare PP/EPDM/nano-CaCO 3 composites. The effects of RCCR on the crystallization behavior of PP in the composites were studied by DSC. The crystal type structure of PP in the composites was studied by X-ray diffraction and polarized optical microscope (POM). It was found that RCCR acts as a nucleating agent. It initiates PP crystallizing at higher temperature, and lowers degree of crystallinity and crystal size, and induces the formation of β crystallite. RCCR in collaboration with EPDM can obviously increase the content of β crystallite. Isothermal crystallization studies reveal that the activation energy of PP in PP/EPDM/RCCR is lower than that of PP/EPDM/CCR.A modified nano-CaCO3 (RCCR) was prepared by mixing the stearic acid treated nano-CaCO3 (CCR) with organic agent containing —OH, —COOH, and C=C groups and it was then melt compounded with polypropylene PP and Ethylene-propylene-diene mischpolymer (EPDM) to prepare PP/EPDM/nano-CaCO 3 composites. The effects of RCCR on the crystallization behavior of PP in the composites were studied by DSC. The crystal type structure of PP in the composites was studied by X-ray diffraction and polarized optical microscope (POM). It was found that RCCR acts as a nucleating agent. It initiates PP crystallizing at higher temperature, and lowers degree of crystallinity and crystal size, and induces the formation of β crystallite. RCCR in collaboration with EPDM can obviously increase the content of β crystallite. Isothermal crystallization studies reveal that the activation energy of PP in PP/EPDM/RCCR is lower than that of PP/EPDM/CCR.

Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin

The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field. This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2, an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A (E51)/HTDE-2 hybrid resin in detail. Fourier transform infrared (FT-IR) spectrometer, scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMA) and molecular simulation technology are used to study the structure of HTDE-2, performance and toughening and reinforcing mechanism of the HTDE-2/E51 hybrid resin. It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin, and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content. The impact strength and fracture toughness of the hybrid resin with 9 wt-% HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively, furthermore, the tensile and flexural strength can also be enhanced about 20.7% and 14.2%, respectively. The glass transition temperature and thermal degradation temperature, however, are found to decrease to some extent.