MODIFICATION OF POLYAMIDE 6 WITH POLYAMINOAMIDE-g-POLY(ETHYLENE GLYCOL)VIA HYDROLYTIC POLYMERIZATION

To enhance the impact strength of polyamide 6, hydrolytic polymerization modification by the polyaminoamide-g-poly(ethylene glycol) (PAAEG) derivatives with poly(ethylene glycol) (PEG) molecular weight of 400-10000 was studied. Amide groups of polyaminoamide segments were postulated to form hydrogen bonding with polyamide 6, and hydroxy groups of PAAEG units were expected to react with carboxylic acid groups of polyamide 6 forming copolymers during the polymerization. The improved compatibility in amorphous regions of blends has been confirmed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) of fracture surfaces. The effects of PAAEG on the water absorption and notch sensitivity of blends were investigated, using water uptake measurement and mechanical testings, respectively. For comparison, pure polyamide 6 and the blend of PEG/polyamide 6 were also investigated. The addition of PAAEG retarded the crystallization of polyamide 6, but did not make remarkable influences on its crystalline structure. As a consequence of the strong interactions between the dispersed phases and polyamide 6 matrices, PAAEG was a more suitable additive for improving the notched impact strength of polyamide 6 than PEG.

Morphology and Crystalline Structure of Inclusion Compounds Formed between Poly(ethylene glycol) and Urea

The poly（ethylene glycol） （PEG, with Mw 2000）-urea inclusion compound （IC） crystallized at high temperature region showed two typical orientations, flat-on and edge-on crystals. 2D-XRD and polarized FTIR spectroscopy revealed that the PEG chains within urea channels were perpendicular to the substrate in fiat-on oriented crystals, while PEG chain axes were parallel to the substrate and lay along the growth direction in the edge-on crystals. FT1R absorption bands of PEG in the ICs are sensitive to orientation of the crystals. A scheme of PEG chain packing in the urea IC channel was proposed, which could explain the orientation of the crystal nucleus causing the two types of morphologies. Furthermore, functioning of PEG2000 chain end with analine had significantly influence on the morphology and orientation of the inclusion compound crystals, due to the defects caused by large terminal groups included in the urea channel.

Observation of banded spherulites and lamellar structures by atomic force microscopy

Lamellar structures of banded spherulites of poly(?caprolactone)/poly(vinyl chloride) (PCL/PVC) blends are observed using tapping mode atomic force microscopy (AFM). The surface of the PCL/PVC banded spherulites presents to be concentric periodic ups and downs. The period of the bands corresponds to the extinction rings under the polarized optical microscopy observa-tion. The lamellae with edge-on orientation in the ridges and the flat-on lamellae in the valleys of the banded spherulites are observed clearly. The twisting between the edge-on and flat-on lamel-lae is also observed.

Preparation of Core-Shell Structured Polyacrylic Modifiers and Effects of the Core-Shell Weight Ratio on Toughening of Poly(butylene terephthalate)

Core-shell structured polyacrylic（named CSSP） impact modifiers consisting of a rubbery poly（n-butyl acrylate） core and a rigid poly（methyl methacrylate） shell with a size of about 353 nm were prepared by seed emulsion polymerization. The CSSP modifiers with different core-shell weight ratios（90/10, 85/15, 80/20, 75/25, 70/30, 65/35 and 60/40） were used to modify the toughness of poly（butylene terephthalate）（PBT） by melt blending. It was found that the polymerization had a very high instantaneous conversion（ 95.7%） and overall conversion（99.7%）. The morphology of the core-shell structure was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. Differential scanning calorimeter was used to study the crystallization behaviors of PBT/CSSP blends. The dynamic mechanical analyses of PBT/CSSP blends showed two merged transition peaks of PBT matrix, with the presence of CSSP core-shell structured modifier, that were responsible for the improvement of PBT toughness. The results indicated that the notch impact strength of PBT/CSSP blends with a core-shell weight ratio of 75/25 was almost 8.64 times greater than that of pure PBT, and the mechanical properties agreed well with the SEM observation.