Impact of electron beam treatment on copolymers of polylactide and poly(trimethylene carbonate) in an air atmosphere

Abstract

The effect of exposure of polylactide (PLA) and poly(trimethylene carbonate) (PTMC) statistical copolymers to ionizing radiation was studied by means of EPR spectroscopy. In addition, the influence of radiation‐induced processes on thermal properties, miscibility of the components, weight average molecular weight (Mw) and number average molecular weight (Mn) were investigated for doses in the range of 0–200 kGy. In copolymers containing PLA and PTMC components in a ratio of 30:70 and 70:30 PLA radicals identified in the homopolymer under cryogenic conditions were dominant. This showed that PTMC radical centers either recombine or are transferred to PLA along the macromolecules. The results obtained for the non‐irradiated and irradiated samples showed that the glass transition values measured by differential scanning calorimetry and calculated using the Fox equation were similar and indicated compatibility between the constituents of the tested copolymers and their miscibility. Mw and Mn changes measured by gel permeation chromatography were used to determine the radiation yield of scission G(S) and cross‐linking G(X). In the case of PLA and PLA‐rich copolymers, the difference between G(S) and G(X) with increasing dose increased, thus the chain scission predominated over cross‐linking. For PTMC rich copolymer, the effect was opposite.

Regulation of polylactic acid using irradiation and preparation of PLA–SiO2–ZnO melt-blown nonwovens for antibacterial and air filtration

“…34 The chain damage caused by this effect will inhibit the movement and crystallization of the PLA chain. 18 Viscosity will certainly decrease when PLA molecular weight drops, which is good for melt flow and curing moulding of PLA melt during melt-blown spinning processes. 38 As depicted in Fig.…”

“…The possible reason is that the chain structures of PLAγ50 and PLAγ100 were destroyed by irradiation, and PLA with different lengths of chain can't be spun uniformly in the melt-blown spinning process, resulting in an uneven fiber diameter distribution. 18 Furthermore, when the fiber diameter of MBs is less than 2 μm, it is difficult to wind.…”

“…16 As reported previously, the number average molecular weight of PLA decreased with the increase in irradiation dose, which is caused by two degradation mechanisms of PLA exposed to gamma rays in the air, namely, main chain breakage and hydrogen abstraction chain breakage. 17,18 Thus, the irradiation technology provides feasibility for increasing the melt index and improving the melt-blown spinnability of PLA.…”

A Comprehensive Investigation of the Structural, Thermal, and Biological Properties of Fully Randomized Biomedical Polyesters Synthesized with a Nontoxic Bismuth(III) Catalyst

“…The temperature value of the minimum of the effect generated on the dDSC curve was taken for this purpose [ 24 ]. Additionally, in order to estimate T g of the copolymers, a simple Fox Equation (11) was used [ 25 ]. where T g is the glass transition of copolymers constructed from components 1 and 2 with weight fractions w 1 and w 2 , respectively.…”