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. 2021 Sep 10;13(18):3062.
doi: 10.3390/polym13183062.

The Effect of Dialkyl Peroxide Crosslinking on the Properties of LLDPE and UHMWPE

Pollyana S M Cardoso  1   2 , Marcelo M Ueki  2 , Josiane D V Barbosa  1 , Fabio C Garcia Filho  3 , Benjamin S Lazarus  4 , Joyce B Azevedo  5
Affiliations

The Effect of Dialkyl Peroxide Crosslinking on the Properties of LLDPE and UHMWPE

Pollyana S M Cardoso et al. Polymers (Basel). .

Abstract

Peroxide has been considered a chemical agent that can be used to tune the properties of polymeric materials. This research evaluated the influence of different concentrations of dialkyl peroxides on the mechanical, thermal, and morphological properties of linear low-density polyethylene (LLDPE) and ultra-high molecular weight polyethylene (UHMWPE). The neat polymer, as well as those with the addition of 1% and 2% by mass of dialkyl peroxides, were subjected to compression molding and immersion in water for 1 h, under controlled temperatures of 90 °C. The values of the gel content found in the samples indicated that the addition of peroxide to the LLDPE and to the UHMWPE promoted the formation of a reticulated network. The structure obtained by the crosslinking led to less reorganization of the chains during the crystallization process, resulting in the formation of imperfect crystals and, consequently, in the reduction in melting temperatures, crystallization and enthalpy. The mechanical properties were altered with the presence of the crosslinker. The polymers presented had predominant characteristics of a ductile material, with the occurrence of crazing with an increased peroxide content.

Keywords: LLDPE; UHMWPE; crosslinking; peroxide.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Thermal map of the plateaus of the press. (a) Lower and (b) upper.
Figure 2
Figure 2
Particle size distribution of LLDPE and UHMWPE.
Figure 3
Figure 3
SEM images of pure polymer powders: (a) LLDPE; (b) UHMWPE.
Figure 4
Figure 4
Typical strain versus stress curves for (a) LLDPE and (b) UHMWPE with the addition of 1% and 2% by mass peroxide.
Figure 5
Figure 5
Variation of tension at the rupture of LLDPE and UHMWPE with 0%, 1% and 2% peroxide.
Figure 6
Figure 6
Deformation at the rupture of LLDPE and UHMWPE with 1% and 2% peroxide.
Figure 7
Figure 7
LLDPE and UHMWPE elastic modulus with 1% and 2% peroxide.
Figure 8
Figure 8
Resistance to the impact of LLDPE and UHMWPE with 1% and 2% peroxide.
Figure 9
Figure 9
Gel contents of LLDPE and UHMW PE with 1% and 2% peroxide.
Figure 10
Figure 10
Thermograms of LLDPE peroxide: (a) melting peak and (b) crystallization peak.
Figure 11
Figure 11
Thermograms of UHMWPE peroxide: (a) melting peak and (b) crystallization peak.
Figure 12
Figure 12
Thickness of the lamella determined by DSC for the LLDPE is UHMWPE with 0%, 1% and 2% peroxide.
Figure 13
Figure 13
Variation in the degree of crystallinity of LLDPE and UHMWPE with 0%, 1% and 2% peroxide.
Figure 14
Figure 14
SEM images of crosslinked LLDPE (a) 0% peroxide, (b) 1% peroxide and (c) 2% peroxide.
Figure 15
Figure 15
SEM images of UHMWPE with (a) 0% peroxide, (b) 1% peroxide and (c) 2% peroxide.
See this image and copyright information in PMC

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