Crosslinking of low‐density polyethylene by diisocyanates for superior barrier properties

Abstract

ABSTRACT:The chemical modification of low-density polyethylene (LDPE) resins with hexamethylene diisocyanate and toluene diisocyanate was achieved. The reaction of LDPE with diisocyanate was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 3326, 1620, and 1572 cm Ϫ1 corresponding to ONOH stretching, O(CAO)ONH 2 stretching, and ONOH bending in an amide moiety, respectively, was observed. Modified films of excellent clarity and uniform thickness were obtained by the solution casting of crosslinked polyethylene. The oxygen transmission rate (OTR), water vapor transmission rate (WVTR), grease resistance, and thermal properties of the modified films were studied. The results clearly indicate that the OTR was improved by 35% and that grease resistance was improved by 90 -125% in the crosslinked LDPE films with little change in their strengths. The heat seal characteristics, however, showed that relatively higher temperatures were needed to achieve efficient sealing in these films. Differential scanning calorimetry showed a decrease in the melting temperature from 104°C for LDPE to 101°C for both of the crosslinked LDPE films.

Properties of bacterial cellulose produced in grape medium by native isolate Gluconacetobacter sp

“…Synthetic polymers normally have low WVTR (18–20 g/m 2 /day) and a high OTR (8000–14000 cc/m 2 /day). 24 Hence the present result is reverse of synthetic polymers.…”

Modelling Gas Transmission in Cylindrical Dynamic Accumulation Oxygen Transmission Rate Chambers to Explore Implications of Oxygen Sensor Location Relative to Samples

“…The pressure or volume of the oxygen receiving chamber is monitored over time, and the OTR is determined from the change in volume or pressure. This method has been used by several researchers …”

“…This method has been used by several researchers. [10][11][12] A common method for measuring OTR is described by ASTM D3985 13 and is based on a steady state approach. This method is cited in a number of studies.…”

Comparison of New Dynamic Accumulation Method for Measuring Oxygen Transmission Rate of Packaging against the Steady‐State Method Described by ASTM D3985

“…The pressure or volume of the oxygen receiving chamber is monitored over time, and the OTR is determined from the change in volume or pressure. This method has been used by several researchers, including George et al, 2 Laohakunjit and Noomhorm 3 and Raj et al, 4 but is experimentally difficult and not considered as accurate as other methods. One of the most popular methods for measuring OTR is ASTM D3985, 5 which is used by many researchers, including Brennan et al, 6 Dufrense et al, 7 Kim et al 8 and Mexis et al 9 ASTM D3985 is considered to be a steady-state, isostatic method using a coulometric sensor.…”

“…As oxygen accumulates over time, AOR tends to zero. Equation (4) suggests that plotting the natural logarithm of AOR versus time should yield a straight line with a slope proportional to OTR. Converting from moles to conventional OTR units of cubic centimetres of O 2 at standard temperature and pressure (STP) yields Equation (5):…”