Interfacial and mechanical properties of γ‐Fe2O3/segmented polyurethane/poly(vinyl chloride) composites

Segmented polyurethane (SPU)/poly(vinyl chloride) (PVC) blends were particulated with γ‐Fe₂O₃. Interfacial properties of the composite were studied through the adsorption behaviors of SPU and PVC and their blends on γ‐Fe₂O₃ particles surface. Mechanical properties of the composite were measured with dynamic mechanical analysis and tensile test measurements. PVC with functional groups (FPVC), because of strong interactions, showed preferential adsorption on γ‐Fe₂O₃ compared with SPU and PVC. Moreover, the γ‐Fe₂O₃ particles were covered by FPVC in the γ‐Fe₂O₃/SPU/FPVC composite. The adsorption layer of FPVC protected SPU from catalytic degradation by γ‐Fe₂O₃, resulting in increasing hydrolytic stability for SPU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3030–3035, 2001     

Lifetime expectancy of polyurethane binder as magnetic recording media

The effects of the chemical structure and addition of cross-linking agent and polyvinyl chloride (PVC) on the tensile strength of polyurethanes (PU) binder have been investigated. An expectation of the lifetime of PU binder as magnetic recording media has been performed based on the tensile strength change in different environmental conditions.

It was found that a small number of ester bonds which are directly responsible for the polymer degradation and suitable storage temperature are required to extend the lifetime of the recording media. In addition, the presence of PVC and polyisocyanate (CL) as cross linking agent extends the lifetime of PU binder. For example, poly(hexamethylene carbonate) diol-based polyurethane PU(PCD) in a mixture system such as PU(PCD)/CL/PVD can be expected to have a tensile half life of about 200 years at 20°C.     

Miscibility of segmented polyurethane/poly(vinyl chloride) blends

Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X‐ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard‐segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard‐segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3022–3029, 2001     

Microphase separation and surface properties of segmented polyurethane-Effect of hard segment content

A series of segmented polyurethanes (SPU), based on 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as hard segments (HS) and poly(propylene glycol) (Mn = 1000) as soft segments, were synthesized. Relationships between microphase separation and the surface and adhesive properties were characterized by thermal analysis, X-ray diffraction, contact angle, electron spectroscopy for chemical analysis, T-peel and tensile test measurements. Microphase separation occurred for SPU with an HS content of more than 50 wt% and influenced not only the bulk properties, but also the surface properties. Young's modulus and tensile strength increased abruptly for SPU with an HS content of more than 50wt%. Surface free energy also increased in a stepwise manner at an HS content of about 50wt%. The optimum HS content of SPUs for adhesion, based on T-peel test results, also gave good thermal and mechanical properties.     

Asian Mussel Watch Program: contamination status of polybrominated diphenyl ethers and organochlorines in coastal waters of Asian countries

Mussel samples were used in this study to measure the levels of polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs) in the coastal waters of Asian countries like Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, the Philippines, and Vietnam. PBDEs were detected in all the samples analyzed, and the concentrations ranged from 0.66 to 440 ng/g lipid wt. Apparently higher concentrations of PBDEs were found in mussels from the coastal waters of Korea, Hong Kong, China, and the Philippines, which suggests that significant sources of these chemicals exist in and around this region. With regard to the composition of PBDE congeners, BDE-47, BDE-99, and BDE-100 were the dominant congeners in most of the samples. Among the OCs analyzed, concentrations of DDTs were the highest followed by PCBs > CHLs > HCHs > HCB. Total concentrations of DDTs, PCBs, CHLs, and HCHs in mussel samples ranged from 21 to 58 000, 3.8 to 2000, 0.93 to 900, and 0.90 to 230 ng/g lipid wt., respectively. High levels of DDTs were found in mussels from Hong Kong, Vietnam, and China; PCBs were found in Japan, Hong Kong, and industrialized/urbanized locations in Korea, Indonesia, the Philippines, and India; CHLs were found in Japan and Hong Kong; HCHs were found in India and China. These countries seem to play a role as probable emission sources of corresponding contaminants in Asia and, in turn, may influence their global distribution.