The aim of this work concerned the performances and limitations of uses of two commercial biocides, namely 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate and N 2 -tert-butyl-N 4 -ethyl-6-methylthio-1,3,5-triazine-2,4-diamine (Terbutryn), in low-density polyethylene mulching film for agricultural application. The effects of type and algaecide concentration as well as aging deterioration of low-density polyethylene film surfaces were studied in relation to the mechanical, physical, and antialgal properties of the low-density Downloaded from polyethylene films. For antialgal evaluation, disk diffusion test and chlorophyll-a measurement technique were carried out on Chlorella vulgaris, a single-cell green algae, and Phormidium angustissimum, a blue-green algae. The results suggested that adding 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate or Terbutryn tended to slightly increase the lightness value (L*) of specimens, but did not affect the film mechanical properties. The disk diffusion test indicated that only Terbutryn at 600-1000 ppm resulted in clear zone development against C. vulgaris for low-density polyethylene film specimens. Regarding the quantitative study by chlorophyll-a measurement technique, the antialgal activities of lowdensity polyethylene films gradually improved with increasing algaecide concentrations. Terbutryn appeared to show more effective antialgal efficacy than 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate. Under aging deterioration, Terbutryn-low-density polyethylene films showed less degradation of mechanical properties than neat low-density polyethylene films. However, the antialgal activity of Terbutryn-low-density polyethylene films at various algaecide concentrations was reduced under both accelerated UV weathering and natural outdoor exposure.

Crosslinking and processing characteristics of polyethylenes (PEs) with different molecular architectures, namely high‐density polyethylene (HDPE), linear low‐density polyethylene (LLDPE), and low‐density polyethylene (LDPE), were studied with regard to the effects of peroxide modifications and coolant flow rates. Dicumyl peroxide (DCP) and di‐tert‐butyl peroxide (DTBP) were used as free‐radical inducers for crosslinking the PEs. The characteristics of interest included normalized gel content, real‐time temperature profiles and their cooling rates, exothermic period, crystallinity level, crystallization temperature, and heat distortion temperature. The experiments showed that LDPE exhibited the highest normalized gel content. The real‐time cooling rates, taken from the temperature profiles for all PEs before the crystallization region, were greater than those after the crystallization region. The cooling rate of the PEs increased with the presence of DCP, whereas the crystallization temperature of the PEs was lowered. The HDPE appeared to show the longest exothermic period as compared with those of the LLDPE and LDPE. The exothermic period showed an increase with increasing coolant flow rate, but it was decreased by the use of DCP. As for the effect of peroxide type, the gel content and cooling rate of the PE crosslinked by DCP were higher than those for the PE crosslinked by DTBP. The DTBP was the more effective peroxide for introducing crosslinks and simultaneously maintaining the crystallization behavior of the PE. J. VINYL ADDIT. TECHNOL., 20:80‐90, 2014. © 2014 Society of Plastics Engineers

In this work, low-Density Polyethylene (LDPE) films incorporated with 2-methylthio-4-ethylamino-6-tert.butylamino-triazin-1,3,5, or Terbutryn (TT) was used as anti-algal agent, at different concentrations were evaluated for anti-algal performances. Clear zone test and chlorophyll a measurement method were used for anti-algal evaluations against Chlorella vulgaris (TISTR 8580) and Phormidium angustissimum (TISTR 8979) as testing algae. Mechanical properties and surface color changes of LDPE were also observed for the effect of algaecide addition. It was found that addition of TT in the LDPE specimen did not significantly alter the tensile strength, tensile elongation and toughness properties of materials. For anti-algal test, it should be noted that the greater clear zone area (clear zone test) or smaller chlorophyll a content (chlorophyll a measurement method) the better anti-algal activities. It was found that the clear zone of the TT filled LDPE sample was observed with C. vulgaris but was not seen with P. angustissimum. When the TT concentration in LDPE was greater than 600 ppm, the C. vulgaris did not grow.