Development of Bio-based Unsaturated Polyester Resins from Natural Oils or their Derivates - Green Materials from Plant Oils - page 169

8.2.5.5 Mass Spectrometry
The mass spectra were recorded on a WATERS Q-TOF Premier mass spec-
trometer with electrospray ionization (ESI-MS).
8.2.5.6 Gel Permeation Chromatography
Samples were analyzed at 25 1C using a GPC with a 515 pump (Waters
Corporation, USA) equipped with a 2414 refractive index detector (Waters).
The columns were Styragel HR1 and HR2 (300 7.8 mm, Waters). The flow
rate of the eluent tetrahydrofuran (THF) was 1.0 mL min 1 . Samples in THF
were passed through a 0.45 mm filter (Millipore Corporation, USA) into a
200 mL loop. A series of narrow distributed polystyrene standards (Polymer
Laboratories, USA) with molar masses of 580-10 5 gmol 1 were used for the
calibration of molar mass.
8.2.5.7 Gel Time
The t gel measurements of the cured oil-based UPRs were tested following
the procedure specified in GB/T 7193-2008. Typically, 100 parts of the UPR/
COPERMA resin and 2.0 parts benzoyl peroxide as initiator were placed
together in a beaker and then the beaker was placed in a water bath at
25 0.5 1C. After mixing for 1 h, 0.02 parts N,N-dimethylaniline as a pro-
moter was added by a pipette and the time was recorded immediately by a
stopwatch. When the resin liquid was able to be drawn out like silk, the t gel
of the resin was recorded.
8.2.5.8 Linear Shrinkage
The l s tests of the cured oil-based UPRs were performed by measuring the
lengths of the impact-test samples with a Vernier caliper.
8.2.5.9 Mechanical Properties
Tensile and flexural tests of the polymer matrices were evaluated using a
SANS7 CMT-4304 universal tester (Shenzhen Xinsansi Jiliang Instrument
Corporation, China). Impact tests of the samples were performed in a XJJY-5
impact tester (Chengde Xinguo Instrument Corporation, China). All the
above tests followed the procedure specified in GB/T 2567-2008. Dumbbell
specimens with a size of 50 10 4mm 3 at the narrow middle part were
produced for tensile tests at a constant draw speed of 5.0 mm min 1 . Cuboid
specimens with a size of 100 15 4mm 3 were produced for flexural tests at a
constant cross-head speed of 10 mm min 1 . Cuboid specimens with a size of
80 10 4mm 3 were produced for impact tests. All the specimens were
polished with abrasive papers to remove surface defects before testing.