Preparation of polyamide 6/polystyrene quasi‐nanoblends by diffusion and subsequent polymerization of styrene in water‐sorbed polyamide 6 pellets

Abstract

Polyamide 6 (PA6)/polystyrene (PS) blends with an average particle size of 103 nm were prepared by diffusion and subsequent polymerization of styrene in water-sorbed PA6 pellets. The pretreatment of PA6 pellets in hot water is prerequisite for successful styrene diffusion. The diffusion process involves replacement of free water in the pellets by styrene, and should be carried out in neat styrene medium to provide concentration gradient between inside and outside of the pellets. The polymerization step was carried out in water medium with benzoic peroxide as the initiator. The diametrical distribution of PS in the blend pellets was investigated by Micro-FTIR, and molecular weight of PS was measured by GPC. DSC measurements showed that the diffusion and polymerization of styrene occur in the amorphous regions of PA6 where the pre-sorbed water locates. PA6/PS quasi-nanoblends reported in this work cannot be obtained by conventional methods.

Morphology and Mechanical Properties of Polyamide 6/Polystyrene Blends Prepared by Diffusion and Subsequent Polymerization of Styrene in Polyamide 6 Pellets

“…PA6 and PS are non-compatible. Further, the maximum PS content in PA6/PS blend pellets prepared by the method of diffusion and subsequent polymerization of styrene in commercial PA6 pellets in the previously reported small-scale procedure was only 6.7% [ 26 ]. Thus, in this work, the conditions for obtaining the maximum PS content were used to carry out large-scale preparation (40 times) in order to obtain sufficient PA6/PS blend pellets for injection molding and evaluating the mechanical properties of this unique blend.…”

“…The distribution of PS in both blend pellets and bars was investigated by Micro-FTIR for A 1 /A 3 (i.e., the ratio of the peak areas of absorption at 758 cm −1 , a characteristic peak of PS, and 1122 cm −1 , a characteristic peak of PA6), as a measure of the PS/PA6 ratio at each measured position. As shown in Figure 1 a, the PS distribution along the diameter direction of a pellet was almost homogeneous and the average value of A 1 /A 3 was slightly higher than that in the small-scale preparation [ 26 ], indicating a slightly higher PS content. ATR-FTIR was used to measure the PS content using a previously-reported calibration curve [ 27 ] and the value was 7.3%, slightly higher than that of the small-scale procedure, and basically in agreement with the Micro-FTIR results.…”

“…Polyamide 6 (PA6) is an important engineering plastic [ 20 , 21 , 22 , 23 ], and PS is a widely used commodity plastic. To take the advantages of both PA6 and PS and overcome the shortages of single polymers, PA6/PS blends have been extensively investigated [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. PA6 and PS are non-compatible due to the large difference in polarity, and PA6/PS blends obtained by traditional melt mixing have very poor mechanical properties [ 30 , 31 ].…”

“…Recently, we reported the preparation of PA6/PS quasi-nanoblend pellets with an average PS particle size of about 100 nm using diffusion and subsequent polymerization of styrene in commercial PA6 pellets [ 26 ]. Although styrene can barely diffuse into dry PA6 due to the small free volume of PA6, the diffusion paths can be opened up by presorbing water, because the sorbed water drastically decreases the glass transition temperature (Tg) and increases the free volume of PA6.…”

Influence of thermo‐oxidative aging on the dynamical mechanical properties and thermal degradation kinetics of glass fiber‐reinforced PA10T composites

“…Among these polymers, most of the PAs with the potential to become valuable materials are always considered as the product with excellent mechanical and thermal properties . More importantly, the emphasis will be put on the nylon polymer materials as a consequence of their significant advantages such as low material cost, low density, corrosion resistance, compound customization, insulation qualities, and good load bearing capacity .…”