Polypropylene recycling

Steps ia polypropylene recycling iaclude size reduction of grinding, washing, rinsing, and dryiag to remove contaminants and produce PP flakes... 

Eew of the products in which polypropylene are used can be recovered in commercial quaUties. An exception is battery casings. In 1994, U.S. capacity for recycling polypropylene from battery casings was 265 million pounds aimuaHy (45). About 75% of the recovered polypropylene is used in new battery cases which have a recycled PP content of about 50%. Total polypropylene recycling capacity was 350 million pounds aimuaHy for an operating rate estimated at 71—90% (45). 

Ismail, H. and Suryadiansyah, S., Thermoplastic elastomers based on polypropylene/natural rubber and polypropylene/recycle rubber blends. Polymer Test., 21, 389, 2002. 

Anonymous. (2010). Scoping study into food grade polypropylene recycling. Available... 

Orgablend Polyamide/polypropylene recycled alloys, PA/PP Elf Atochem... 

Taepaiboon P, Junkasem J, Dangtungee R, Amornsakchai T and Supaphol P (2006) In situ micro-fibrillar-reinforced composites of isotactic polypropylene/recycled poly(ethylene terephthalate) system and effect of compatibilizer, J Appl Polym Sci 102 1173-1181. 

Polypropylene. Polypropylene (PP) is used ia packagiag appHcations as films and ia rigid containers. Battery cases could be considered another packagiag appHcation. Dead batteries are often collected at the poiat of sale of new batteries. In the U.S., some states have laws mandating this. Lead, acid, and plastics, particularly PP from battery casiags is recovered and recycled (3). Care must be taken to limit worker exposure to lead duting this process (44). PP is also recovered from bale wrap and other PP fabrics used for wrappiag ia the textile iadustry and from other containers (45). 

Laboratory tests indicated that gamma radiation treatment and cross-linking using triaHylcyanurate or acetylene produced a flexible recycled plastic from mixtures of polyethylene, polypropylene, general-purpose polystyrene, and high impact grade PS (62). 

Most off-quahty or scrap polypropylene fibers may be repeUetized and blended in small percentages with virgin polymer to produce first-grade spunbonded fabrics. The economics are of great importance in a process where high yields are required in order to be competitive. Some manufacturing equipment direcdy recycles edge-trim back into the extmder where it is blended back into the polymer melt (see Fibers, olefin). 

Polypropylene-derived branched alkyl (0 2) benzene (BAB) has been batch sulfonated using 60—70% oleum in Hquid SO2 solvent at temperatures of — 1 to —8°C, with SO2 serving as a self-refrigerant and viscosity reducer in the process. After sulfonation and digestion, SO2 is stripped, recovered, and recycled (256). 

Processing is relatively easy. In general, products based on S—B—S are processed under conditions appropriate for polystyrene, whereas products based on S—EB—S are processed under conditions appropriate for polypropylene. Pre-drying is not needed and scrap is recycled. 

Prior to smelting, batteries are usually broken up and sorted into their constituent products. Fractions of cleaned plastic (such as polypropylene) case are recycled into battery cases or other products. The dilute sulfuric acid is either neutralized for disposal or recycled to the local acid market. One of the three main smelting processes is then used to reduce the lead fractions and produce lead bullion. 

Figure 12-3. The Himont Inc. Spheripol process for producing polypropylene in a liquid-phase (1) tubular reactor, (2,4) two-stage flash pressure system (to separate unreacted monomer for recycle), (3) heterophasic copolymerization gas-phase reactor, (5) stripper.

In many countries starter batteries are almost 100 percent recycled PVC separators can cause some problems here [67]. A prior separation of PVC from other battery components, which is quite tedious, would be desirable, because a PVC content decreases the recycling purity of the container polypropylene and makes further processing of this plastic more difficult. Also, any chlorine compounds liberated can form environmentally hazardous products with other substances the usual remedy is to install costly filter stations, with the residues representing possibly toxic wastes requiring special disposal methods. 

Dow ABS Nylon 6/6 Polycarbonate Polyethylene, HDPE, LDPE, LLDPE, ULDPE Polypropylene HPPP, CPPP Polystyrene HIPS, GPPS, Recycled, Advanced Styrenic Resin SAN Polyurethane Elastomers Polyolefin Plastomer PC/ABS Crystalline Polymer ABS/TPU... 

Once a consumer has purchased a material made of a polymer, the likelihood of it being recycled is dramatically reduced. In the United States there are three resins that are commonly recycled polyethylene, polypropylene, and polyethylene terephthalate, SPI (The Society of the Plastics Industry) recycling codes, found on the bottom of food containers, provide the consumer with information as to the recyclability of the material. Table 17,1 lists these codes. 

Plastic lumber can be manufactured from mixed-polymer post-consumer recycled materials. One example incorporates polyethylene and polypropylene into a final material. How do processors achieve this incorporation in light of the immiscibility of the two polymers ... 

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