New insight into statistics of the autohesion origination in polymers: a symmetric amorphous polyether-polyether interface

For the first time, a comprehensive analysis of the statistical distribution of the lap-shear strength ( σ ) developed at a symmetric interface of amorphous poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at a temperature of the autohesion origination ( T _a ^origin ) is carried out. After the contact of the two PPO specimens for 24 h at a temperature well below the PPO bulk glass transition temperature ( T _g ^b ), at T _a ^origin = T _g ^b − 126 ^o C, the PPO−PPO interface was self-bonded and thereafter fractured at ambient temperature. The σ distribution dataset σ ( n ) including n measurements is investigated on its conformity to the Weibull and normal distributions. It is shown that the Weibull and normal probability plots, the Gaussian probability density function histogram, and a number of the standard tests for normality describe the σ distribution with varying degrees of success. Among those, the most favorable statistical results supporting the null hypothesis of normality are obtained in the standard tests for normality (in 6 out of 8 performed). An attempt to describe the distribution curve σ ( n ) more correctly is undertaken. It is found that the most appropriate distribution forms are the phenomenological logarithmic and exponential relationships log σ ∼ n , σ ∼ e ^{(a + b n )} and σ ∼ (1– e ^{a n} ) where a and b are the constants.