posted on 2024-01-26, 14:36authored byDongcang Sun, Dong Chen, Chuang Wang, Liu Yang, Changtong Song, Yuhong Ma, Xianhong Zhang, Wantai Yang
This
contribution reported the radical copolymerization of vinyl
acetate (VAc) with vinyl carboxylates bearing branched C7–C9 chains, including vinyl neononanoate (VV-9),
vinyl neodecanoate (VV-10), and vinyl 2-ethylhexanoate (VV-EH), and
the VAc units of the as-prepared copolymers were subsequently hydrolyzed
to vinyl alcohol units in a base medium. With reactivity ratios of r1 = 0.94 (VV-9) and r2 = 0.96 (VAc), the copolymerization of VV-9 and VAc demonstrates
an ideal azeotropic copolymerization. By simply adjusting the initial
feed ratios, terpolymers of VV-9, VAc, and vinyl alcohol (PVVOH) with
different compositions have been successfully prepared. As a proof-of-concept,
their application as modifiers to improve the adhesive, hydrophilic,
and oxygen barrier properties of low-density polyethylene (LDPE) was
evaluated. When the PVVOH with 40 wt % VV-9 units was blended with
LDPE, the dispersed PVVOH phase formed microdomains with a size of
about 1 μm, and there was no observable two-phase structure.
The water contact angles of the PVVOH/LDPE blends were reduced from
103.7 ± 0.9° to 51.1 ± 1.3° and retained after
being soaked in water at ambient conditions for 30 days. PVVOH is
also effective in improving the adhesion between LDPE and aluminum
alloys. With the addition of 25 wt % PVVOH (20 wt % VV-9), the ultimate
shear strength of the lap joint was effectively enhanced from 3.60
± 0.17 MPa (pristine LDPE) to 4.87 ± 0.02 MPa. Furthermore,
the addition of 20 wt % PVVOH reduced the oxygen transmission rates
(OTR) of LDPE film from 145.3 to 52.2 cm3·mm·m–2·day–1·bar–1.