Adhesion Improvement between PE and PA in Multilayer Rotational Molding

Abstract

The aim of this study is to investigate a multilayer structure made of polyethylene and polyamide by rotational molding. Due to the different polarity of these polymers, it is difficult to ensure enough adhesion between created layers. Two methods leading to improve adhesion are introduced. Plasma modification of polyethylene powder, after which new functional groups are bound to the treated surface, may enhance specific adhesion by forming hydrogen bonds with-CONH groups of polyamide. Different strategies of adding material to the mold give rise to complicated interlayer which increases joint strength by mechanism of the mechanical adhesion. Mechanical tests show a significant improvement of joint strength, where treated samples reached two-fold values of peel strength (7.657 ± 1.024 N∙mm−1) against the untreated sample (3.662 ± 0.430 N∙mm−1). During bending test, delamination occurred only in samples that were made of the untreated polyethylene. Adding polyamide during the melting stage of polyethylene powder in rotomolding resulted in the formation of entanglements which improve the peel strength almost eight times in comparison with the sample where the polyethylene was left to completely melt and create smooth interlayer surface.

Experimental Studies on the Influence of Plasma Treatment of Polyethylene in Carbon Fiber Composites: Mechanical and Morphological Studies

“…The other combinations (13P, 13N, 15P, and 15N) follow the same principle. In previous studies, it was shown that oxygen-plasma-treated Dowlex TM 2629.10UE had good wettability, which enhanced the adhesion of matrix with fillers [ 3 , 8 ]. It was evident from the SEM results shown in Figure 3 that the plasma treatment of PE enhanced the adhesion behavior of non-polar polyethylene polymer by providing better chemical interaction and mechanical interlock in the matrix.…”

“…The presence of these polar groups induced creation of polymer chains with free radicals, making it possible to add or interlock functional groups to the surface of the polymers. This would have had a favorable impact on the polymer surface activation by increasing the adhesive nature of the composites [ 3 , 8 ]. Agglomeration of carbon fibers resulted in reduction in the flexural properties of the polymer composites [ 12 ].…”

“…Delamination was observed in untreated PE samples. A flexural strength of 35.4 MPa was observed with PE and PE with plasma treatment, far higher than an untreated combination [ 8 ]. Plasma-treated PE showed better tensile, flexural and impact properties while incorporating natural reinforcements.…”

Development of an Ultrasonic Method for the Quality Control of Polyethylene Tanks Manufactured Using Rotational Molding Technology

“…where n is the number of experiments; p is the number of input (independent) parameters; i is the serial number of the experiment; y i is the actual value of the output parameter in the i experiment; yc i is the calculated value of the output parameter, calculated using a multifactor mathematical model, for the conditions (values of input parameters) of the i experiment; and ym is the average value of the actual value of the output parameter for all n experiments (the general average). Using the obtained particular dependencies, shown in Figures 12-14, a multifactor mathematical model (7) was built based on the generalized Protodyakonov Equation (5) as follows:…”

“…Products obtained via the rotational molding of plastics are characterized by a long service life, chemical resistance, and low cost [ 4 , 5 , 6 ]. At present, the development of new formulations based on various polymers [ 7 , 8 , 9 , 10 ] and fillers for rotational molding is being carried out at an accelerated pace; compositions with clay [ 11 , 12 ], quartz [ 13 ], halloysite [ 14 ], glass fiber or powder [ 15 , 16 , 17 ], copper slag [ 18 ], or graphite [ 19 , 20 ] have also been proposed.…”