Preparation of LLDPE/MgAI-LDH Exfoliation Nanocomposites with Enhanced Thermal Properties by Melt Intercalation

The interlayer surface of MgAl layered double hydroxide （MgAl-LDH） was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions （DS） to get MgAl（H-DS） LDH, and then the MgAl（H-DS） was melt intercalated by LLDPE to get the LLDPE/MgAl-LDH exfoliation nanocomposites. The samples were characterized by Fourier transform infrared （PTIR） spectroscopy, X-ray diffraction （XRD）, ion chromatography, transmission electron microscopy （TEM）, and thermogravimetry analysis （TGA）. The nanoscale dispersion of MgAl-LDH layers in the LLDPE matrix was verified by the disappearance of （001） XRD reflection of the modified MgAl-LDH and by the TEM observation. The TGA profiles of LLDPE/MgAl-LDH nanocomposites show a faster charring process between 210 and 370 ℃ and a higher thermal stability above 370 ℃than LLDPE. The decomposition temperature of the nanocomposites with 10 wt% MgAl（H-DS） can be 42 ℃ higher than that of LLDPE at 40% weight loss.

Modification of Nanocomposites by Melting Intercalation of Polypropylene in Montmorillonite

The polypropylene wax modified by ultraviolet irradiation. The polypropylene-montmorillonite nanocomposiles were prepared by direct melting intercalation oj polypropylene powders. The structure of polypropylene , the polyproprlene irradiated, montmorillinote and polypropylene-montmorillonite composites were studied by XRD, 1R and DSC. The results show that the PP molecules can are oxidized during ultraviolet irradiation , melt polypropylene can intercalate into montmorillonite layer. As a result, the layered distance ( d0.01) of montmorillonite increases, and the melt absorption peak of polypropylene in layer is eliminated.

STUDY OF COMPOSITE BY MELTING INTERCALATION OF POLYACRYLAMIDE IN MONTMORILLONITE

The synthesis of polyacrylamide (PAM)-montmorillinote composite by direct melting intercalation of polymer powders is studied using XRD, IR and DSC. The results show that melt PAM can intercalate into montmorillonite layer. The layered distance(d//0//0//1) of montmorillonite increases, and the melt absorption peak of PAM in layer has eliminated. (Author abstract) 8 Refs.

Melting Intercalation Method to Prepare Lauric Acid/Organophilic Montmorillonite Shape-stabilized Phase Change Material

A kind of novel shape-stabilized phase change material （SSPCM） was prepared by using a melting intercalation technique. This kind of SSPCM was made of lauric acid （LA） as a phase change material and organophilic montmorillonite （OMMT） as a support material. And the thermal properties and morphology of the SSPCM were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM）, scanning electronic microscope （SEM）, scanning calorimeter （DSC）, and differential thermal cravimetry （TG）. The DSC result shows that the phase change temperature of the SSPCM is close to that of LA, and its latent heat is equivalent to that of the calculated value based on the mass ratio of LA measured by TG. The XRD, SEM and TEM results demonstrate that the LA intercalates into the silicate layers of the OMMT, thus forming a typically intercalted hybrid, which can restrict the molecular chain of the LA within the structure of OMMT at high temperature. And consequently SSPCM can keep its solid state during its solid-liquid phase change processing.

Preparation and Properties of Phenolic Resin/Montmorillonite Intercalation Nanocomposites

Phenolic resin/montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation.Properties and structure of the composites were investigated by using XRD,TG and test of softening point.It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/organo-montmorillonite intercalation nanocomposites.Compared with phenolic resin,the intercalation nanocomposites have better heat-resistance,higher decomposition temperatures and less thermal weight-loss.However,these two intercalation methods have different effects on the softening point of the intercalation nanocomposites.Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites,while melt intercalation significantly increases the softening point of the intercalation nanocomposites, probably due to the chemical actions happening in the process of melt intercalation.

SYNTHESIS AND CHARACTERIZATION OF ORGANOMONTMORILLONITE AND POLYAMIDE 66/MONTMORILLONITE NANOCOMPOSITES

The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods prior to the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), and termed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were called modified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG and WAXD. The results show that interlayer spacings of CTAB and nylon modified MMTs are larger than that of sodium MMTs. Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. The nanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs disperse homogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexural properties, were also measured and show a tendency to increase with increase of MMT content and reach the maximum values at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher than that of pure PA 66.

Comparison of Effects of Different Organo-montmorillonites on PA 66 / Clay Nanocomposites

Different organo-montmorillonites （OMMTs） are prepared by modifying montmorillonites （MMTs） with CTAB, PA 1010 salts/CTAB, PEG/CTAB, PVA/CTAB, PVP, PVP/ CTAB and PA 6/CTAB, respectively. These OMMTs were studied by X-ray diffraction and TG. The gallery sizes of them are all larger than that of sodium MMTs. And the decomposition temperatures of them are all much higher than that of MMT and the processing temperature of PA 66, especially OM - 6 and OM - 7, the decomposition temperatures of which are 451.6℃ and 439.1℃, almost the collapse temperature of the native MMT crystal lattice which is more than 5080C. Then PA 66/Clay nanocomposites were synthesized by mixing these OMMTs with PA 66 matrix via melt intercalation. Experimental results indicate that the tensile and flexural properties increase significantly, especially those of PCN - 08. The combination property of PCN- 08 is the best. TEaM photos show that some clay platelets are present in the matrix as exfollated layers, while most of the clay platelets are present as intercalated layers.

Chemical resistance tests on PP-ternary nanocomposite for its application in bioreactor liner fabrication

Continuous usage of bioreactor causes early degradation of most bioreactor liner materials due to the effects of various chemicals, consequently resulting in contamination in the bioprocess. Performance of PP-ternary nanocomposite (PPTN) for its potential application in the fabrication of bioreactor liner material was investigated in this study. The chemical resistance of the composite samples obtained was tested by exposing them to chemicals such as acid, alkaline, water and bacterial solutions, according to ASTM 543-06, and their effects on the composite samples were carefully observed. Specifically, the investigation focused on the changes in the physico-mechanical properties of PPTN following long term of exposure to these chemicals. The results show slight increase in the weight and dimensions of samples in the first few days, followed by constant reading for the period of 4 weeks. The performance in terms of physical properties was in the range of PPTN with 0.61% MWCNT > PPTN 0.45% > PPTN 0.17%. The maximum percentage change in tensile properties, observed in this study, was approximately 10% against PPTN (0.17%), which indicates stable mechanical properties of the composite and invariably suggests that the nanocomposites could serve as a better alternative for bioreactor liner fabrication.