UHMWPE/SBA-15 nanocomposites synthesized by in situ polymerization

Abstract

Different nanocomposites have been attained by in situ polymerization based on ultrahigh molecular weight polyethylene (UHMWPE) and mesoporous SBA-15, this silica being used for immobilization of the FI catalyst bis [N-(3-tert-butylsalicylidene)-

Effect of mesoporous SBA-15 silica on the thermal stability of isotactic polypropylene based nanocomposites prepared by melt extrusion

“…Anyway, the partial overlapping of the high temperature weight loss of PP13 with the low temperature weight loss of PP80 allows suspecting some PP degradation within SBA-15 particles. Some DSC results for nanocomposites based on ultra-high molecular weight polyethylene and SBA-15 particles and on polyethylene and decorated MCM-41 have pointed out the existence of confined polymer within the mesoporous channels 43,44 .…”

UHMWPE/HDPE in-reactor blends, prepared by in situ polymerization: Synthetic aspects and characterization

“…On the other hand, when fixing the Ti:Zr proportion at 50:50, the results seem to point out a decrease of the molar mass of the blends at increasing Al/M T ratios (compare FIM010,and FIM013 or FIM001 and FIM006). This trend may be related to the role of trimethylaluminum, TMA (one of the different species present in MAO) on deactivation pathways that contribute to a loss of the polymerization control and that will reduce the polymer chain growth [19,25]. Figure 3 shows the thermogravimetric curves under inert and oxidative environments for the blends prepared at the longest times.…”

“…The synthesis and characterization of pure SBA-15 was carried out as described elsewhere [19]. Briefly, 13.2 g of P-123 were first dissolved in 500 mL of water at room temperature, followed by the addition of 45 mL of 37% aq.…”

“…SBA-15 was characterized by powder X-ray diffraction on a Panalytical X'Pert pro diffractometer using Cu K α radiation filtered by Ni and a X'Celerator detector. The powder pattern (not shown) indicates the typical ordered hexagonal structure identified by the three diffraction peaks that can be indexed as (100), (110) and (200) associated with the p6mm hexagonal symmetry [19]. The textural properties were assessed by nitrogen adsorption at -196 ºC using an ASAP 2010 Micromeritics equipment.…”

“…The pre-activation (PA) method, which consists in the contact of both catalysts with methylaluminoxane, MAO, before their further interaction with the SBA-15 particles, has been selected as immobilization approach. Our previous results have shown that the diffusion of the catalyst within the support may be facilitated in the PA approach and that very high molar masses can be attained [19]. In this study UHMWPE/HDPE blends with different compositions, molar masses and filler contents (around 5 and 10 wt% of SBA-15) were prepared by varying the Ti:Zr molar proportion between the two single-site catalysts, the Al/M T ratio (Al = aluminum; M T = transition metal) and the polymerization time.…”