Chifei Wu

Organic hybrid of chlorinated polyethylene and hindered phenol. I. Dynamic mechanical properties

Dynamic mechanical properties and microstructure of an organic hybrid consisting of chlorinated polyethylene (CPE) and 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were investigated. The AO-80 clearly exhibited two second-order transitions at 6 and 69 °C in addition to the melting: the transition at lower temperature is assigned to the glass transition, and the transition at higher temperature is considered to be caused by the dissociation of hydrogen bond between the hydroxyl groups of AO-80. When blending with CPE, part of AO-80 molecules was dispersed into the CPE matrix, and most of them formed an AO-80-rich phase. As a result, a novel transition appeared above the glass-transition temperature of the CPE matrix. It was assigned to the dissociation of the intermolecular hydrogen bond between the α-hydrogen of CPE and the hydroxyl groups of AO-80 within the AO-80-rich phase. Dynamic mechanical properties and microstructure of CPE/AO-80 hybrid were controlled by the thermal treatment. It was found that the CPE/AO-80 hybrid is a good damping material and shows a shape memory effect.

Organic hybrid of chlorinated polyethylene and hindered phenol. II. Influence of the chemical structure of small molecules on viscoelastic properties

The viscoelastic properties and stabilities of those properties of organic hybrids consisting of chlorinated polyethylene (CPE) and tetrakis[methylene-3-(3-5-di-tert-butyl-4-hydroxy phenyl)propionyloxy]methane (AO-60) and triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methyl phenyl)propionyloxy] (AO-70) were investigated. The CPE/AO-70 hybrids show only one transition, whereas for the CPE/AO-60 hybrids, one novel relaxation appears above the glass-transition temperature of CPE. This relaxation on the higher temperature side in the mechanical spectrum for CPE/AO-60 is associated with the appearance of the AO-60-rich phase. Furthermore, the stabilities of the viscoelastic properties and microstructures of the organic hybrids consisting of CPE and multifunctional hindered phenols are dominated by the strength of the intermolecular interaction between CPE and phenols and the conformations of the middle skeletal parts of hindered phenols.

Viscoelastic properties of an organic hybrid of chlorinated polyethylene and a small molecule

The dynamic mechanical properties of an organic hybrid consisting of chlorinated polyethylene (CPE) and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ) were investigated. All the CPE/DZ hybrids showed a single loss tangent (tan δ) peak in the mechanical spectra. The peak area under the tan δ/temperature curves around the mechanical loss peak was examined to characterize the damping properties of the CPE/DZ hybrids. We found that there exists a bending point in the relation between the glass-transition temperature (Tg) and DZ content and that the value of Tg is saturated in the higher DZ contents, suggesting that excess DZ molecules show self-aggregation and are reorganized.

Organic hybrid of chlorinated polyethylene and hindered phenol. IV. Modification on dynamic mechanical properties by chlorinated paraffin

Binary systems of chlorinated polyethylene (CPE) and chlorinated paraffin (CP) or 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) and their ternary systems were investigated by dynamic mechanical analysis, thermal analysis, and infrared spectrum analysis. Adding CP into CPE/AO-80, in which one novel relaxation appears above the glass-transition temperature of CPE, can increase not only the peak height but also the minimum value between two peaks. The tan δ value in the middle of the two peaks for CPE/CP/CPE was found to be proportional to the slope (d ln E′/dT) of the E′ curve at an identical temperature. The addition of CP caused changes in many of the hydrogen bonds: a decrease in hydrogen bonds between the hydroxyl groups of AO-80, a reinforcement of hydrogen bonds between the hydroxyl groups of AO-80 and α-hydrogens of CPE, and the formation of other hydrogen bonds between the carbonyl groups of AO-80 and α-hydrogens of CPE. Those changes are useful to improve the temperature dependence of tan δ and to enhance the stability of the dynamic mechanical properties.

Organic hybrid of chlorinated polyethylene and hindered phenol. III. Influence of the molecular weight and chlorine content of the polymer on the viscoelastic properties

The influences of the molecular weight and chlorine content of chlorinated polyethylene (CPE) on the dynamic mechanical propertiesof an organic hybrid consisting of CPE and 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were investigated. All CPE/AO-80 hybrids clearly exhibited two kinds of relaxations, and their magnitudes varied according to the molecular weight and chlorine content of CPE. This was due to a change in the ratio of AO-80 molecules dispersed in the CPE-rich domain and the AO-80-rich domain. A comparison of the jump intensity in differential scanning calorimetry curves with the maximum value of the second tan δ peak demonstrated that the second relaxation was caused by the dissociation of intermolecular hydrogen bonding within the AO-80-rich domain.