Mechanical enhancement of ripples and dimples in CaCO₃/low-density unsaturated polyester resin composites

Abstract

Incorporation of different fine grain calcium carbonate into CaCO 3 /low-density unsaturated polyester resin (LDUPR) composites was studied and evident mechanical enhancement of CaCO 3 on composites was investigated. Preliminary experiment results indicated that proper content of CaCO 3 was less than 30.00 phr (parts per hundreds of resin), suitable preparation temperature range was from 72.0°C to 80.0°C, and initiator content was 1.80 phr. Optimal preparation conditions of CaCO 3 /LDUPR samples were obtained with the presence of 25.00 phr CaCO 3 and 2.50 phr NH 4 HCO 3 at 76.0°C based on preliminary experiments. The lowest apparent density of A-CaCO 3 /LDUPR composite was 0.53±0.02 g·cm −3 with a compressive strength of 20.27±0.51 MPa·g −1 ·cm 3 , and the highest specific compressive strength of the sample was 38.25±1.43 MPa·g −1 ·cm 3 . It is attributed to the hindrance to cross-linking between unsaturated polyester and styrene, and to the decrease of exothermic heat of the polymerization, which was caused by the existence of CaCO 3 . Unusual matrix microstructure with regular ripples and dimples formed by CaCO 3 , and the particular mechanical enhancement of regular ripples and dimples in composites were explored. 'CaCO 3 reefs' concept, reefs-induced ripples, dimples of streams flowing, and resolution of external force with major force further being consumed models comprised the regulated mechanical enhancement of CaCO 3 in CaCO 3 /LDUPR composites. This particular polymerization retarding and mechanical strengthening were obvious for the finest grain CaCO

High Mechanic Enhancement of Chopped Carbon Fiber Reinforced-Low-Density Unsaturated Polyester Resin Composite at Low Preparation Temperature with Facile Polymerization

“…Different apparent densities of low-density unsaturated polyester resin samples were calculated and were in the range of 0.41~0.50 g·cm −3 with the presence of 2.00 phr NH 4 HCO 3 at temperature from 52.0 to 60.0 °C. These calculated values of apparent density matched those of low-density material in References of [ 5 , 18 , 19 ], which were between 0.30 g·cm −3 and 1.00 g·cm −3 . Therefore, 52.0~60.0 °C was set as the curing temperature for CCFR-LDUPR samples preparation.…”

“…In a commercial process, gel time of a resin glue was usually controlled between 23 and 35 min [ 20 , 21 , 22 ]. As reported previously in the literature, gel time was adjusted utilizing initiator of tert-butylperoxy benzoate (TBPB, AkzoNobel, Shanghai, China) alone for low-density unsaturated polyester resin or low-density unsaturated polyester resin composite materials preparation to control the polymerization to be slow enough to maintain the homogeneous distribution of bubbles, and low-density unsaturated polyester resin or its composite was treated from 70 to 84 °C [ 4 , 5 ]. In the study, synergistic effects of initiator methyl ethyl ketone peroxide (MEKP-II) and accelerator cobalt naphthenate were put forward and explored.…”

“…However, there are no “dimples” in the resin matrix of the low-density unsaturated polyester resin sample. It is deduced that external forces were decomposed and transmitted along each branch of the “dimples” produced by chopped fibers, resulting in the improvement of mechanic performance of the matrix [ 5 ].…”

“…As a novel light-weight material, low-density unsaturated polyester resin composites were prepared by foaming methods. It combined with chopped glass fibers or fillers to form composites, including chopped glass fiber-reinforced low-density unsaturated polyester resin (CGFR-LDUPR) [ 4 , 5 ]. In the future, researches of chopped carbon fiber-reinforced low-density unsaturated polyester resin (CCFR-LDUPR) composites will be the highlight of chopped carbon fiber-reinforced thermosetting resin-based composites or low-density unsaturated polyester resin based composites.…”

“…Different to the above applications of carbon fiber in epoxy resin, and different from previous preparation of low-density unsaturated polyester resin composites at moderate temperature [ 4 , 5 ], carbon fiber was used in unsaturated polyester resin and CCFR-LDUPR composite was prepared at a low temperature from 52.0 to 60.0 °C, NH 4 HCO 3 , a foaming agent with a wide decomposition temperature range, was used in the study. Synergistic effects at lower temperature were realized in this study in the presence of methyl ethyl ketone peroxide (MEKP-II) and an accelerator of cobalt naphthenate.…”