Polymer Blends (or Alloys)

A practical guide to polymer miscibility

The weathering of polymers is reviewed with attention concentrated on the mechanisms of degradation and stabilization, the methods of testing weatherability, and the predictive modelling of weathering behaviour. An introduction to the chemical mechanisms of degradation and stabilization is given and reference made to some of the many reviews available in the literature. Significant emphasis is placed here on engineering aspects, such as the way that weathering influences fracture mechanisms. The difficulties associated with relating accelerated laboratory tests with outdoor service behaviour are discussed. The complexities of the degradation processes limit modelling of the rate of degradation to rather specific systems and the predictions cannot be generalized.

Weathering of polymers: mechanisms of degradation and stabilization, testing strategies and modelling

Influence of tacticity of poly(methyl methacrylate) on the compatibility with poly(vinylidene fluoride)

A brief overview of the important issues governing the behavior of polymer blends is presented. Thermodynamic issues which determine the phase behavior of blends are reviewed and qualitatively related to physical interactions between blend components. The influence of melt processing conditions on the resulting properties and behavior of both miscible and immiscible blends is reviewed. The physical properties of blends are reviewed and illustrated by examples from recent work on miscible blends of polycarbonate with a copolyester and on the immiscible blends of polystyrene with high density polyethylene.

Polymer blends and alloys—a review of selected considerations

Transition temperatures by thermo-optical analysis (TOA) and by DSC were measured on films of polystyrene (PS), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO resin) and nine homogeneous blends of these polymers. The TOA procedure consists of automatically monitoring light transmission through birefringent scratches in a film during heating at constant rate in a microscope hot stage between crossed (90°) plane polarizers. The TTOA transition temperature, defined as the temperature of birefringence disappearance in the scratches, increased monotonically from 113°C for pure PS to 222°C for pure PPO resin at a 10°/min heating rate. The Tg (DSC) similarly ranged from 99°C to 212°C at a 20°/min heating rate. The TOA technique as described should be a useful addition to thermomechanical studies of transparent polymers and polymer blends.

Thermo-optical and differential scanning calorimetric observations of mobility transitions in polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) blends

The glass transition temperatures (Tg) and specific heat increments (ΔCp) at Tg of S/AMS statistical copolymers having weight fractions AMS of 0.00, 0.09, 0.17, 0.26, 0.36, and 0.44 are (by DSC) 380.0 (0.280), 384.2 (0.275), 388.8 (0.284), 391.5 (0.275), 398.3 (0.272), and 405.9 (0.27) °K (J·g− ·deg−), respectively. The Tg (ΔCp) for the PPO resin are 492.2 (0.221). The glass transitions of P(S/AMS) (1) + PPO resin (2) blends having w2 = 0.25, 0.50, and 0.75 were also measured. Examination of the copolymer and blend Tg vs. composition data indicates that a relation recently proposed by Couchman gives a somewhat better approximation than the simple Fox relation. However, the nonadjustable k = ΔCp2/ΔCp1 constant in the Couchman relation must be replaced by a smaller empirical k to give a true match of calculated to observed Tg.

Glass transitions of styrene/α‐methylstyrene statistical copolymers and of their blends with PPO® resin

Blending of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO resin) with a triblock butadiene–styrene–butadiene copolymer (Kraton 101) monotonically increases the softening temperature of the latter as measured by TOA. The TOA transition temperatures of the styrene/PPO resin phases closely approximate those of polystyrene/PPO resin blends having the same styrene/aromatic ether unit compositions. Uniform mixtures of the styrene blocks with the poly(2,6-dimethyl-1,4-phenylene oxide) molecules is inferred.

Thermo‐optical analysis of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/triblock styrene–butadiene–styrene copolymer blends

An explicit expression is derived for the weight distribution function of polymer molecules in a photodegraded film. A most probable weight distribution of linear molecules is assumed initially present; normally incident, monochromatic light obeying a single Beer-Lambert absorption relation is the photolyzing radiation. The dependence of the weight distribution upon the film's optical thickness and the integrated incident light flux is illustrated by curves computed according to the derived functions. Predicted gel permeation chromatograms are indicated.

Molecular weight distribution in a polymer film degraded by light

Discussion de «regle du pouce»: il faut doubler la concentration en absorbant UV pour avoir la meme duree de vie d'un plastique lorsque l'intensite des UV augmente de 50%

Allan R. Shultz

Papers

Thermo-optical and differential scanning calorimetric observations of mobility transitions in polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) blends

Glass transitions of styrene/α‐methylstyrene statistical copolymers and of their blends with PPO® resin

Thermo‐optical analysis of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/triblock styrene–butadiene–styrene copolymer blends

Molecular weight distribution in a polymer film degraded by light

Protection of polymers from degradation by ultraviolet light: Compensation for increased UV light intensity by increased UV absorber concentration