Oligoester and Polyester Production via Acido-alcoholysis of PET Waste

A new chemical way has been introduced to recycle poly(ethylene terephthalate) via acido-alcoholysis. Acido-alcoholysis has been developed as a green way to produce oligoesters from PET waste which can be used as building blocks to new compostable polyesters. Organic acids and 1,4-butanediol were used as reagents. The solvolysis products were further reacted with diglycidyl ethers of different diols to obtain higher molecular weight polyesters. The resulted materials were tested with GPC, FTIR, TGA, functional group analysis methods and composting. It was found that the reagents in acido-alcoholysis fully incorporated into the reaction product obtaining oligoesters with carboxyl and hydroxyl end groups. Significant mass loss and fragmentation was observed on oligo- and polyesters after composting

A versatile characterization of poly(N-isopropylacrylamideco- N,N'-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology

Poly(N-isopropylacrylamide-co-N,N"-methylene-bisacrylamide) (P(NIPAAm-co-MBA)) hydrogels were prepared in water using redox initiator. The copolymer composition at high conversion (> 95%) was determined indirectly by HPLC (high performance liquid chromatography) analysis of the leaching water and directly by solid state 13C CP MAS NMR (cross polarization magic angle spinning nuclear magnetic resonance) spectroscopy of the dried gels, and was found to be close to that of the feed. The effect of cross-linker (MBA) content in the copolymer was investigated in the concentration range of 1.1–9.1 mol% (R:90–10; R = mol NIPAAm/mol MBA) on the rheological behaviour and mechanical strength of the hydrogels. Both storage and loss modulus decreased with decreasing cross-linker content as revealed by dynamic rheometry. Gels R70 and R90 with very low cross-linker content (1.2–1.5 mol% MBA) have a very loose network structure, which is significantly different from those with higher cross-linker content manifesting in higher difference in storage modulus. The temperature dependence of the damping factor served the most accurate determination of the volume phase transition temperature, which was not affected by the cross-link density in the investigated range of MBA concentration. Gel R10 with highest cross-linker content (9.1 mol% MBA) behaves anomalously due to heterogeneity and the hindered conformation of the side chains of PNIPAAm

Effect of Composting on the Behavior of Polyolefin Films - A True-to-Life Experiment

Commercial polypropylene (PP), high-, medium- and low density polyethylene (HDPE, MDPE, LDPE) films, as well as MDPE films containing pro-oxidative additives and thermoplastic starch (TPS) were composted for six weeks together with biologically degradable films, such as poly (lactic acid) (PLA), Ecovio (BASF), Mater Bi(Novamont) and cellophane. Visual appearance of the polyolefin-based films did not change significantly, while the biologically degradable films fell apart. Thickness and mechanical properties of the polyolefin-based films also did not vary significantly after composting. The thickness of the degradable films however increased due to biofilm formation and finally decreased due to biodegradation, and their mechanical properties drastically dropped. FTIR proved the formation of carbonyl absorption of commercial and of the additive-containing films respectively) after composting due to oxidation. The FTIR-spectrum of the biodegradable films showed drastic change after composting. Formation of free radicals was detectable by ESR-spectroscopy, if pro-oxidative additive containing MDPE film was exposed for one week to sunlight, and the intensity of free radical formation increased after composting. The number-average molecular mass of MDPE films containing pro-oxidative additives decreased, low molecular mass fractions appeared and polydispersity increased after composting. Commercial polyolefin films were covered by microorganisms much more densly than films containing pro-oxidative additives detected by SEM. Even TPS did not increase the quantity of microorganisms. Biodegradable films were densly covered by microorganisms of different types and they became porous and holes were observable on their surface. It can be concluded that composting had no significant effect on the behaviour of the commercial PP and PE films. Signs of initial degradation were observable on MDPE films with pro-oxidative additives and TPS after 6 weeks composting, although it cannot be considered as biological degradation. Non of the tested polyolefin films suffered such degree of degradation in compost, as the biologically degradable films. It may be concluded that polyolefin films neither degrade in compost nor they undergo biodegradation

Ferroelectric liquid crystal polymers

The ferroelectricity of liquid crystal polymers can be utilized in electro-optic display devices. Liquid crystal polymers (LCP´s) unite the properties of liquid crystals and of polymers, where the mesophase can be frozen in the polymer glass. The mesophase responsible for ferroelectricity is the chiral smectic C$^*$ phase (SmC$^*$), which can be generated by mesogen side groups bearing chiral carbon atoms. This also means that ferroelectric liquid crystal polymers are side chain polymers with the mesogen groups in the side chain. According to the main chain, polysiloxanes, polyacrylates, polyethers and polyvinylethers are the most important groups of FLCP´s. Our work can be divided into two main parts: One is the synthesis and characterization of the mesogen side groups, the other is the preparation of the corresponding polymer via polymerization or polymeranalog reaction. As the polymer main chain, polysiloxanes and polyacrylates were selected for the syntheses. For polysiloxanes the following mesogen groups were synthesized: Br-(CH2)10-COO-C6H4-COO-C6H4-COO-CH2-C*H(CH3)-C2H5 (S)-4´-(2-methyl-butyloxicarbonyl)-phenyl-4-[11-bromo-undecanoyloxi]-benzoate The polymer can be prepared by the addition of poly(methyl-hydrogen-siloxane) to the double bond of the mesogen monomer: For polyacrylates the following mesogen side group was prepared: CH2=CH-(CH2)n-O-C6H4-COO-C6H4-O-CH2-C*H(CH3)-C2H5 n = 8 (S)-4`-(2-methyl-butyloxy)-phenyl-4-(9-decenyloxy)-benzoate n = 9 (S)-4`-(2-methyl-butyloxy)-phenyl-4-(10-undecenyloxy)-benzoate The mesogen side group can be transferred to the polymer acrylate via a polymeranalog reaction. The synthesis of the mesogen side group for polysiloxanes is described in detail

Monitoring the degradation of partly decomposable plastic foils

We have monitored the behaviour of different polyethylene foils including virgin medium density polyethylene (MDPE), MDPE containing pro-oxydative additives (238, 242) and MDPE with pro-oxydative additives and thermoplastic starch (297) in the soil for a period of one year. A foil based on a blend of polyester and polylactic acid (BASF Ecovio) served as degradable control. The experiment was carried out by weekly measurements of conductivity and capacity of the soil, since the setup was analogous to a condenser, of which the insulating layer was the foil itself. The twelve replications allowed monthly sampling; the specimen taken out from the soil each month were tested visually for thickness, mechanical properties, morphological and structural changes, and molecular mass. Based on the obtained capacity values, we found that among the polyethylene foils, the one that contained thermoplastic starch extenuated the most. This foil had the greatest decrease in tensile strength and elongation at break due to the presence of thermoplastic starch. The starch can completely degrade in the soil; thus, the foil had cracks and pores. The polyethylene foils that contained pro-oxydant additives showed smaller external change compared to the virgin foil, since there was no available UV radiation and oxygen for their degradation. The smallest change occurred in the virgin polyethylene foil. Among the five examined samples, the commercially available BASF foil showed the largest extenuation and external change, and it deteriorated the most in the soil