W. S. Chow

Mechanical, Morphological and Thermal Properties of Polycarbonate/SEBS-G-MA/Montmorillonite Nanocomposites

Nanocomposites based on polycarbonate (PC) containing sodium montmorillonite (NaMMT) and maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MA) were prepared by melt compounding method followed by injection molding. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed the formation of intercalated nanocomposites. Incorporation of SEBS-g-MA into the PC/MMT nanocomposites enhanced ductility and impact strength but slightly reduced tensile strength and stiffness. The glass transition temperature (T g – detected from DMTA) and onset temperature (T onset – detected from TGA) of the PC nanocomposites was increased in the presence of SEBS-g-MA. For this PC/NaMMT system, SEBS-g-MA could act as an effective toughening agent.

Thermal Properties, Fracture Toughness and Water Absorption of Epoxy-Palm Oil Blends

Epoxidized palm oil (EPO) was blended with cycloaliphatic epoxide, epoxy novolac and diglycidyl ethers of bisphenol-A. The fracture toughness and thermal properties of epoxy/EPO blends were characterized using single-edge notched bending tests and differential scanning calorimetry. Increased EPO loading improved the fracture toughness (K IC ) of the epoxy blends. The epoxy blends with higher EPO loading exhibited higher degree of conversion. The glass transition temperature (T g ) of the epoxy blends shifted to higher temperature as the increasing of DSC heating rate. Water absorption caused T g reduction of epoxy blends but it was determined that the water molecules absorbed were totally reversible.

Fracture Toughness Enhancement of Epoxy by Organo-Montmorillonite

Epoxy nanocomposites were prepared by addition of organo-montmorillonite (OMMT). The intercalation-ability of the OMMT was characterized using X-ray diffraction (XRD). The fracture toughness of the epoxy/OMMT nanocomposites was examined using single edge notched bending (SENB) tests. The OMMT (1–4 wt%) was successfully exfoliated in the epoxy matrix, however, the epoxy/OMMT (5 wt%) exhibited intercalated structure. Surprisingly, the fracture toughness of epoxy nanocomposites was increased by the increasing loading of OMMT. The result correlated well with the observation of FESEM micrographs where the epoxy/OMMT (5 wt%) exhibited highest degree of plastic deformation, attributed to the high toughness imparted by the incorporation of OMMT.

Water Absorption and Hygrothermal Aging Behaviors of SEBS-g-MAH Toughened Poly(lactic acid)/Halloysite Nanocomposites

Poly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were exposed to hygrothermal aging at three different temperatures, i.e., 30, 40 and 50°C. The analysis was focused on the water diffusion kinetics and physical changes induced by the hygrothermal degradation. The water absorption kinetics of the PLA/HNC composites at immersion temperature of 30 and 40°C conforms to Ficks law. The equilibrium water absorption (Mm ) and diffusion coefficient (D) values are dependent on the SEBS-g-MAH content and immersion temperatures. Hydrolytic chain scission provoked significant molecular weight reduction. Nevertheless, adding SEBS-g-MAH improved hygrothermal stability of the PLA/HNC nanocomposites.

Water Absorption Kinetics and Hygrothermal Aging of Poly(lactic acid) Containing Halloysite Nanoclay and Maleated Rubber

AbstractnPoly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were produced using melt compounding followed by compression molding. The effects of hygrothermal aging on the thermal properties and functional groups changes of the HNC reinforced PLA (with and without SEBS-g-MAH) at three different temperatures (i.e., 30, 40 and 50xa0°C) were analyzed using differential scanning calorimetry and Fourier transform infrared spectroscopy techniques. The diffusion coefficient (D) of PLA was decreased by the incorporation of HNC and SEBS-g-MAH. The activation energy of water diffusion (Ea) of PLA/HNC/SEBS-g-MAH nanocomposites was higher than that of pure PLA. The glass transition temperature (Tg), cold-crystallization temperature (Tcc) and melting temperature (Tm) of the PLA sample were shifted to lower temperature and the effect was more pronounced at 50xa0°C. The carbonyl index values of all PLA samples increased after immersed in 40 and 50xa0°C, which is due to the formation of higher amount of carboxyl groups during the hydrolysis process.

Mechanical and Thermal Properties Enhancement of Poly(Lactic Acid)/Halloysite Nanocomposites by Maleic-Anhydride Functionalized Rubber

Poly(lactic acid) (PLA)/halloysite composites were prepared using melt compounding followed by compression molding. Maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) was used to toughen the PLA composites. The mechanical properties of the PLA composites were studied through tensile, flexural, and impact tests. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The fracture surfaces of the composites were assessed by using field emission scanning electron microscopy (FESEM). The impact strength and thermal properties of the PLA/halloysite composites were increased by addition of SEBS-g-MAH.

Thermal and Antistatic Properties of Polypropylene/Organo Montmorillonite Nanocomposites

Both polypropylene (PP) and PP/organo-montmorillonite (OMMT) masterbatch containing antistatic agent (3–9 wt%) were prepared by using co-rotating twin screw extruder followed by injection molding. PP/OMMT masterbatch was prepared by mixing PP, OMMT and maleated PP (PPgMAH). The PP nanocomposites were characterized by using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), thermogravimetry analyzer (TGA), hardness and surface resistivity tests. XRD results indicated that AA could promote the intercalation in PP/OMMT nanocomposites. The decomposition temperature of PP/OMMT/AA nanocomposites is higher than that of PP/OMMT. The hardness, degree of crystallinity and surface resistivity of PP nanocomposites was influenced by the addition of antistatic agent.

Mechanical and Hygrothermal Aging Study on Polystyrene/Organo-montmorillonite Nanocomposites

Melt intercalation blending of polystyrene (PS)/organo-montmorillonite (OMMT) was prepared using the extrusion technique followed by compression molding. The loading of OMMT ranged from 2–10 wt.%. Maleic-anhydride grafted poly(styrene-block-(ethylene-co-butadiene)-block-styrene) (SEBSgMAH) was added to PS/OMMT composites in order to improve the impact strength of the composites. The concentration of SEBSgMAH ranged from 5–15%. The mechanical properties of PS/OMMT were characterized using flexural and impact tests. The morphological properties of the composites were studied using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Intercalation of the OMMT layered silicates in the PS matrix was conformed by the XRD spectra. The incorporation of SEBSgMAH improved the flexural strength, flexural displacement, and impact strength of PS/OMMT significantly. The percentage of retention and recovery in impact strength of PS/OMMT nanocomposites after being subjected to hygrothermal aging were increased by the addition of SEBSgMAH.

Effects of N,N′-Ethylenebis(stearamide) on the Properties of Poly(ethylene terephthalate)/Organo-montmorillonite Nanocomposite

Poly(ethylene terephthalate)/organo-montmorillonite (PET/OMMT) nanocomposites were melt-compounded using twin screw extruder followed by injection molding. N,N′-ethylenebis(stearamide) (EBS) was selected as a dispersing agent to improve the dispersibility and exfoliation of OMMT clay in PET matrix. Morphological properties of the PET/OMMT nanocomposites were examined by using X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy. Thermal properties of the nanocomposites were characterized by using dynamic mechanical thermal analysis. It was found that the OMMT are well dispersed and exfoliated in the presence of EBS. Remarkable enhancement in impact strength and storage modulus of PET/OMMT was achieved by the addition of EBS.

Impact, Thermal, and Morphological Properties of Poly(Lactic Acid)/Poly(Methyl Methacrylate)/Halloysite Nanotube Nanocomposites

ABSTRACT Poly(lactic acid)/poly(methyl methacrylate) blends containing halloysite nanotube (2 and 5 phr) and epoxidized natural rubber (5–15 phr) were prepared by melt mixing. The impact strength of poly(lactic acid)/poly(methyl methacrylate) blend was slightly improved by the addition of halloysite nanotube. Adding epoxidized natural rubber further increased the impact strength of poly(lactic acid)/poly(methyl methacrylate)/halloysite nanotube nanocomposite. Single Tg of poly(lactic acid)/poly(methyl methacrylate) is observed and this indicates that poly(lactic acid)/poly(methyl methacrylate) blend is miscible. The addition of halloysite nanotube into poly(lactic acid)/poly(methyl methacrylate) slightly increased the Tg of the blends. The epoxidized natural rubber could encapsulate some of the halloysite nanotube and prevent the halloysite nanotube from breaking into shorter length tube during the melt shearing process. GRAPHICAL ABSTRACT