Polymer composites susceptible to biodegradation

Abstract

Kompozyty polimerowe podatne na (bio)degradacjêStreszczenie -Na podstawie przegl¹du literatury (obejmuj¹cej publikacje a¿ do roku 2007 w³¹cznie) scharakteryzowano metody wytwarzania i niektóre w³aoeciwooeci u¿ytkowe mieszanin polimer syntetyczny/skrobia ze szczególnym uwzglêdnieniem mo¿liwooeci zwiêkszenia podatnooeci na biodegradacjê tego rodzaju uk³adów na podstawie polietylenu. W ramach badañ w³asnych okreoelono wp³yw wprowadzenia 10 % samego epoksydowanego kauczuku naturalnego (ENR) lub mieszaniny ENR z nadtlenkiem dikumylu (DCP) na biodegradacjê otrzymywanych metod¹ reaktywnego wyt³aczania kompozytów polietylenu lub polipropylenu zawieraj¹cych 60 % skrobi plastyfikowanej gliceryn¹ (SG). Stwierdzono, ¿e po 36 miesi¹cach przebywania próbek w glebie ubytek masy wynosi 30-35 % w zale¿nooeci od sk³adu kompozytu, przy czym ubytek ten zwi¹zany jest g³ównie z degradacj¹ fazy skrobiowej. Zmiany w³aoeciwooeci mechanicznych podczas rozci¹gania w toku trwaj¹cego do 36 miesiêcy testu glebowego sugeruj¹ tak¿e istotne zmiany struktury matrycy poliolefinowej, zw³aszcza sieciowanie PE i degradacjê PP. Na zaobserwowane zmiany istotny wp³yw wywiera obecnooeae dodatków (ENR, DCP), czas degradacji oraz odczyn gleby. S³owa kluczowe: biodegradacja w glebie, polietylen, polipropylen, plastyfikowana skrobia, kompozyt, w³aoeciwooeci mechaniczne. POLYMER COMPOSITES SUSCEPTIBLE TO BIODEGRADATIONSummary -On the basis of the literature data (review covering publications up to 2007) the methods of preparation and some useful properties of the systems synthetic polymer/starch were characterized. Especially the possibility to increase the susceptibility to degradation of the systems based on polyethylene/starch with compatibilizers or polyesters (polycaprolactone)/starch made by reactive extrusion has been discussed. The results of own research concerned the effect of the introduction of 10 % of epoxidized natural rubber (ENR) or the mixture of ENR with dicumyl peroxide (DCP) into the composites of polyethylene or polypropylene (produced by reactive extrusion), containing 60 % of starch plastified with glycerol (SG), on their biodegradation (Table 1). It was found that after 36-month hold time of the samples in the soil, the weight loss was in the range 30-35 % dependently on the composition (Fig. 1) but of course the weight loss concerned mainly the starch phase (Table 1). Changes of tensile properties during 36-month soil test ( Fig. 2 and 3) suggest also significant changes in the structure of polyolefin matrix, especially PE crosslinking and PP degradation. These observed changes are strongly dependent on the presence of additives (ENR, DCP), degradation time and soil reaction.

Degradation of Polyethylene and Biocomponent-Derived Polymer Materials: An Overview

“…This is confirmed by the relatively large number of scientific papers investigating the properties of starch and polyethylene mixtures [5,[29][30][31][32][33][34][35]. Starch is an easily available and cheap vegetable feedstock and, thanks to its properties, it is widely used in many branches of the economy, above all, in the industry of high-molecular-weight plastics as a biodegradable filler [1]. As it was demonstrated by Broeren et al [36], the possibility of obtaining starch for the production of biodegradable polymer materials does not only concern plant feedstocks.…”

“…They are usually a mixture of compounds (homologs) with different chain length, i.e. compounds of different molecular weights [1,2]. Molecular weight is an important feature that determines the properties of a polymer and is closely related to polymerisation, i.e.…”

“…Considering the above, it can be concluded that the structure of the resulting polymer can be controlled by choosing the appropriate polymerisation conditions and initiators. Many authors emphasise that the spatial structure of a polymer is very important for its properties, as it decides, among others, about its density, thermal stability, and mechanical strength [1,3,8]. However, the use of polymers with unmodified and singlecomponent structures is currently relatively rare.…”

“…By origin, polymers are divided into: natural polymers (biopolymers), synthetic polymers (obtained by chemical synthesis), and modified polymers (natural or synthetic polymers whose structure was chemically or physically changed) [1,4,5]. Natural polymers are an indispensable element of the animate world (e.g.…”

“…carbohydrates, proteins, fats, nucleic acids, cellulose, starches, oils), and are subject to natural decomposition processes in the environment (photodegradation, chemical degradation, mechanical degradation, biodegradation). These processes take place simultaneously and complement each other [1]. In turn, synthetic polymers are produced mainly from petrochemical feedstocks (crude oil, natural gas), and usually constitute a foreign body in the environment, whose decomposition can last from dozens to even hundreds of years.…”