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The statistical distribution of the lap-shear strength ( σ) developed upon the contact of the thick (bulk) films of amorphous polystyrene (PS) and poly(methyl methacrylate) (PMMA) for a short-term (1 h) contact at healing temperatures ( T) in the surroundings or well below the bulk glass transition temperature ( T ), down to T = T − 50 K, has been analysed in the frameworks of the Weibull model. The Weibull modulus ( m) and the scale parameter ( σ ) have been estimated over a broad interval of T. It has been shown that, in general, the σ distribution follows a standard Weibull distribution function both at the compatible PS-PS and PMMA-PMMA and incompatible PS-PMMA interfaces. [ABSTRACT FROM AUTHOR]

For the first time, the strength distribution upon the bonding onset between the contacting glassy polymer samples has been analysed by employing the Weibull statistics. It has been found that the distribution of the lap-shear strength ( σ) developed between the contacting pieces of such representative amorphous polymers as atactic polystyrene (PS) and poly(methyl methacrylate) (PMMA) at the time-temperature healing conditions at which the interface bonding starts follows the Weibull distribution function. It has been shown that the σ distributions for the compatible PS-PS and PMMA-PMMA and incompatible PS-PMMA interfaces are not affected by the factor of thermodynamic compatibility of the PS and PMMA segments. The estimated values of the Weibull modulus m and of the scale parameter σ for the weak polymer-polymer interfaces investigated have been compared with those estimated for the tensile strength s of the PS and PMMA monolithic bulk samples which were used for the interface healing experiments and of the ultra-high-strength inorganic quasi-brittle materials reported in the literature. [ABSTRACT FROM AUTHOR]

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) has been employed to analyse the surfaces of poly(2,6-dimethyl-1,4-phenylene-oxide) (PPO) samples prior to contact and after fracture of the PPO-PPO auto-adhesive joints which formed during the contact of two identical PPO samples at temperatures of 146 or 156 °С that are lower than the PPO bulk glass transition temperature by 70 or 60 °С, respectively. The differences in the intensity of ATR-FTIR spectra for the original and fractured PPO surfaces found have been discussed in the frameworks of the molecular mechanisms of fracture. [ABSTRACT FROM AUTHOR]

In order to study the anharmonic elastic behaviour of solid polymers, we introduce a Brillouin technique, including the appropriate theoretical background, to obtain the complete tensor of elastic stiffness constants of third-order. First results are reported for glassy polycarbonate. [ABSTRACT FROM AUTHOR]

Measurements of the plastic deformation kinetics for several glassy (PS, PC, PI-polyimide, PET, epoxy-amine network), semi crystalline polymers (PBT, PET) and blends (ABS, PC:ABS, PC: PBT) were performed for the unidirectional compression loading conditions by using constant temperature deformation calorimetry. The experiments have permitted us to follow the changes of the mechanical work ( A), the heat of deformation ( Q) and differences between these quantities, i.e., internal energy (Δ U) stored in samples during their loading and unloading. Experiments have shown that the large portion (45-85%) of the mechanical work of deformation ( A) is converted to heat ( Q). The rest of A is converted to internal energy (Δ U) stored in deformed samples. Δ U is quite high as compared with metals [1,2]. After complete unloading of plastically deformed samples, i.e., samples carrying irreversible at Tplastic deformation (ɛ), some amount Δ(Δ U) of stored energy disappeared. The amount of (Δ U and Δ(Δ U) are different for different polymers. All data are analyzed in the framework of the model proposed in [3,4]. The experiments support the deformation model where the plasticity of glassy polymers is the process of nucleation and development of so-called PDs-plastic local shear defects of nonconformational and nondilatational nature. [ABSTRACT FROM AUTHOR]

The important role of the entanglements in the deformation of high-molecular-weight glassy polymers is demonstrated by two phenomena: the build-up of material resistance in polymethylmethacrylate after chain interpenetration and the intrinsic crazing of polycarbonate which is observed when the entanglement network reaches its limits of extension. [ABSTRACT FROM AUTHOR]