PET degrades during melt processing, reducing molecular weight which leads to lower mechanical properties. Fibers based on recycled PET can use cleaned flake or pellets with lower molecular weight of the recycled PET. All other applications require improved molecular weight indicated by higher intrinsic viscosity (IV). Food contact bottle applications require improved IV (0.72-0.74 dL/g minimum) and removal of contaminants such as acetaldehyde. Recycled PET strapping requires 0.74 minimum IV, and film and sheet applications require minimum 0.7 IV. The established method to produce food-grade recycled PET from cleaned, post-consumer recycled flake are solid state polymerization (SSP), vacuum decontamination, and some depolymerization methods. These remove contaminants and also increase IV. An alternative process is promoted by the PTP Group, a Netherlands-based PET recycler. PTP uses a silicone modifier in its patented process to recycle post-consumer plastic into a food-grade, chemically modified PET-MTM. Silicon-based modifier acts as a catalyst to integrate low-molecular weight oligomers into the PET chain. The resulting PET-M resin has a slightly different molecular structure than conventional PET, but is competitive with virgin PET and recycled PET. PTP Group plans to offer the new silicone modifier in masterbatch form as well as liquid. PTP calls the new material PET-M (modified) to distinguish it from other food-grade recycled PET (rPET). It has better elasticity and better oxygen barrier. Elongation at break is 250% vs. about 120% for standard RPET. Acetaldehyde content is less than 0.5 ppm, suitable for water bottles. PET-M has received food-contact approval from the FDA. Clarity is slightly less than that of virgin PET. PET-M can be used in green or blue preforms, and up to 20% PET-M can be used in clear preforms without hurting clarity. Another new process is promoted by PTI Recycling Systems, a subsidiary of Plastic Technologies Inc. LLC's LNOTMC (The "C" in the brand name refers to the "compacted" resin that is the end result) process reduces flake to an extremely small particle size, which allows more efficient decontamination by devolatilizing under vacuum. Phoenix Technologies is a worldwide leader for the manufacture of recycled PET (rPET). Using a proprietary process developed at Phoenix in conjunction with its sister company, Plastic Technologies, Inc. (PTI), the LNOTM C technology palletizes and crystallizes recycled post-consumer PET for direct sale and reuse back in to consumer packaging applications. The patented fine mesh filtration process enables the production of rPET that processes like virgin PET but requires less energy to manufacture. And since it runs like virgin PET, no special process changes are needed to use our rPET. The process relies on Phoenix's patented "extremely small particle size" technology. The tiny particle size enables much more efficient decontamination compared to other processes, resulting in faster output and significant energy savings. The technology produces rPET with superior color and yield as compared to other methods. Further, it has lower acetaldehyde levels which positively impact taste properties. Another benefit is its higher intrinsic viscosity (IV) or molecular weight which more closely matches the IV found in virgin resins. This enables higher package performance. The resulting rPET is ideally suited for a variety of food and beverage applications including water, carbonated soft drinks, juices, fruit, baked goods, meats and cheeses. Package types include bottles, thermoformed containers and films, as well as drinking cups, vegetable oil and deli containers. Krones has developed complete PET recycling systems for bottle-to-bottle recycling, for recovery operation. This process produces PET flakes, which are suitable as a recyclate for re-use in direct contact with foods and beverages and meet the stipulations of both the American FDA (Food and Drug Administration) and the German BfR guidelines (Federal Institute for Risk Assessment). Krones’ modularised system concept can be used for outputs of 500 kg/hr or 1000 kg/hr. The PET recycling process comprises a washing module and a bottle-to-bottle (B2B) module. The steps in this process comprise material preparation, soaking/washing/rinsing, separation into PET and polyolefins (POs), subsequent mechanical/thermal drying and thick/thin separation, followed finally by the removal of migrated constituents in a “super-cleaning” function. An alternative method to increase intrinsic viscosity and restore properties of condensation polymers is to add chain extenders during melt processing. BASF's family of Joncryl® ADR chain extenders are multi-functional epoxy oligomers that react with the acid end groups of PET, "bridging" them back together to rebuild the molecular weight. Joncryl ADR is added at low levels (< 1%) to recycled PET during melt processing to restore mechanical properties of recycled PET to levels. ALLINCOTM CBC (carbonyl-bis-caprolactam from DSM CBC (carbonyl-bis-caprolactam) chain extender can be used in PA to upgrade properties of industrial regrind in products such as carpet fibers and film. CBC was found to react too slowly for use in PET, but a new developmental product, ALLINCOTM PBOX, reacts faster in PET and has no emission byproducts. This chain extender reacts with carboxylic end groups and also improves hydrolytic stability, which is important in some industrial PET yarn and monofilament markets. ALLINCOTM PBOX could find use in recycled PET in these markets. However, its higher cost has some constraints. Kenrich Petrochemicals' Ken-React titanate coupling agents catalyze in-situ copolymerization that extends chains during melt compounding. For PET, typical addition levels would be between 0.2 and 0.6% by weight. (References: Special Chem)