1, 1-Bis (aryl) propane-2-O-aryl ether type lignin-based polymers (lignophenols) were synthesized through the phase-separation system composed of phenols and a concentrated acid. Ligno-p-cresol (LP-P), ligno-2, 4-dimethylphenol (LP-24X), ligno-pcresol : 2, 4-dimethylphenol=1 : 1 (LP-P/24X) were hydroxymethylated (HM) to give network (N)-, linear (L)-and semi-network (N/L)-type structures, respectively. In order to use these as matrices of various composites, HM-lignophenols were hybridized with powdery inorganic materials such as glass, iron, or talc, by applying heat and pressure. The resulting composites with a glossy surface had high dimensional stability. Talc-HM-LP-P composites, which formed rigid network structures, had the highest resistance to solvents such as acetone and THF. Furthermore, using the switching functionality of lignophenols (nucleophilic attack of C1-phenols to C2), the composites were re-separated into lignophenol fractions and inorganic materials. The physical and recycling properties of composites could be controlled by the structure of lignophenol matrices and/or density, morphology and accessibility for reagents of inorganic materials.

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The corrosion tests of two kinds of epoxy resins were conducted by immersing them in an alkaline (KOH) solution. One was the resin of low resistant to alkaline cured with an acid anhydride, the other was the resin of high resistant cured with an amine. They were ground and used for recycling as fillers of the both epoxy resins.Variation in the combination of matrix resin (M) and filler (F) was as follows : C1=M cured with acid anhydride (Ac)/F cured with Ac; C2=M cured with Ac/F cured with amine (Am);C3=M cured with Am/F cured with Am; C4=M cured with Am/F cured with Ac. For C1, potassium hydroxide penetrated into interfaces of the fillers exposed on the surface of a specimen and promoted dissolution around the filler. Although the strength decreased due to dissolution of fillers at the surface, no more penetration occurred inside the specimen. For C2, potassium hydroxide penetrated deeply inside the specimen through filler/matrix interfaces. Because of fillers on the surface falling off and inner matrix around fillers dissolving gradually, the strength decreased remarkably. On the other hand, for C3, potassium hydroxide penetrated into the layer close to the surface and the strength decreased.The strength recovered by drying the specimen reversibly. For C4, fillers at the surface dissolved and potassium hydroxide penetrated deeply inside through the interfaces.Fillers inside the specimen dissolved gradually. The strength decreased and did not recover by drying it. In general, chemical degradation is thought to be one of important factors for these recycled materials, since they have low resistance to alkaline environment caused by filling ground resins.

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We have studied the chemical recycling of wastes from unsaturated polyester resin products such as buttons for clothes.The resin wastes were ground and decomposed in glycol with an acid, base or ester exchange catalyst. The decomposition rate by the basic catalyst was larger than that by the acid or the ester exchange catalyst. When they were treated with ethylene glycol and NaOH catalyst for 2.0 hrs at 290°C, the decomposition of 84.6% was attained and the molecular weight of a resulting product showed Mn = 156 and Mw / Mn = 1.06. The decomposition at 200°C gave a phthalic glycol. The destruction of crosslinking in a styrene/fumarate copolymer was observed at the temperatures over 230°C. The same phenomenon could occur, too, in the case of a styrene / maleic anhydride (75/25) copolymer in glycol at such a high temperature. The degradation product was then reacted with maleic anhydride to give a new unsaturated polyester (Mn = 846, Mw = 7,468 : cf., the commercial one; Mn = 1,646, Mw = 5,366). The bending strength of the recycled resin was 77.8 MPa (the commercial one : 92.1 MPa).

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Through the phase-separation system, lignocellulosics were converted and separated to lignin-based polymers (lignophenols) and hydrolyzed carbohydrates. The resulting lignophenols had unique functions such as highly phenolic characteristics, very light colors and high stabilities which conventional lignins did not have. The phase-separation system composed of phenol derivatives and a concentrated acid was brought to act by a simple stirring operation for about 60 minutes at ambient temperature in an open container. To enhance the efficiency of the phase-separation reaction, the system interface between the phenolic and aqueous phases was irradiated by ultrasound. The ultrasonication greatly accelerated both the hydrolysis of carbohydrates and the grafting of p-cresol to native lignin to give ligno-p-cresol in a high yield (ca. 90% of Klason lignin). The ligno-p-cresol from the treatment with ultrasonication had high molecular weight (about 30,000) and a high dispersion index, due to effectiveness in the hydrolysis of carbohydrates, compared to that derived by the control reaction.

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The main objectives of this study were to investigate the use of polymeric MDI (P-MDI) with recycle chips from a used particleboard to a new one again. Using melamine-urea-formaldehyde resin (MUF) and replacing 20% of wood chips by the recycled-chips, the bending strength of PB decreased 26% from that of the original.
But using P-MDI, the lowering of board characteristics was depressed comparing with the PB made with MUF resins.
The P-MDI-based PB with formaldehyde-catching additives showed a formaldehyde emmission of 0.3mg/l, and was classified as JIS-EO grade.

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Supercritical water, which has unique properties and is environment-friendly, attracts much attention as a medium for conducting chemical reactions. Decomposition of plastic waste in supercritical water has been studied as an innovative technology for recycling. This article shows an overview of fundamental investigations and processing consideration on the decomposition of plastics in supercritical water, including details regarding the effects of temperature and pressure. PET and Nylon 6, which are condensation polymerization plastics, were able to hydrolyze with high efficiency in supercritical water to respective monomers (terephthalic acid and ε-caprolactam). Decomposition in supercritical water is also a powerful-method for liquefaction of addition polymerization plastics such as polyethylene and polypropylene. Decomposition of thermosetting resins in supercritical water could afforded chemical raw materials, but in less satisfactory yields. Flow-reaction processing concepts, which are indispensable to put this method to practical use, were developed for recovery of monomer or oil conversion.

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Recycling of such waste plastics (MWP) has progressed since the recycling law was carried out in 1997 because expensive recycling fee was paid. Especially, recycling of used PET bottles advances and is to be applied in chemical recycling as B to B due to its purity and the recycling fee. The recycling fee made possible even the chemical recycling of chlorine-containing MWP and their recycling amount increased drastically. The processes and fundamental dechlorination in thermal degradation and in NaOH solutions were reviewed briefly. A plan using such dechlorinated MWP for reduction of carbon dioxide has been proposed and it has been stressed that the goal of dropping the recycling fee should be that for the garbage treatment cost.

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