| Product | Generic | Company |
| OKITEN® | LDPE | DIOKI d.d. |
| OLEFLEX | Polyolefin, Unspecified, TPO (POE) | Japan Polyolefins Co., Ltd. (JPO) |
| Oleform | PP, Unspecified | Chisso America Inc. |
| Olehard | PP, Unspecified | Chisso America Inc. |
| Olesafe | PP, Unspecified | Chisso America Inc. |
| OMIKRON | PP Copolymer, PP Homopolymer, PP Random Copolymer | TECNOPOL |
| OMNICOLOR® | TP, Unspecified | Clariant Masterbatches |
| OnColor™ | PVC, Unspecified, TP, Unspecified | PolyOne Corporation |
| OnColor™ ComPete™ | Polyester, TP | PolyOne Corporation |
| OnFlex™ | TPE | GLS Thermoplastic Elastomers |
| OnFlex™ BIO | TPE | GLS Thermoplastic Elastomers |
| OnForce™ LFT | Nylon 66, PP Homopolymer | PolyOne Corporation |
| OP - ABS | ABS | Oxford Polymers |
| OP - Acetal | Acetal (POM) Copolymer, Acetal (POM) Homopolymer | Oxford Polymers |
| OP - PBT | PBT | Oxford Polymers |
| OP - PC - Filled | PC | Oxford Polymers |
| OP - PC - Filled/Lubricated | PC | Oxford Polymers |
| OP - PC - Lubricated | PC | Oxford Polymers |
| OP - PC - Unfilled | PC | Oxford Polymers |
| OP - PC/ABS | ABS+PC | Oxford Polymers |
| OP - PC/PBT | PC+PBT | Oxford Polymers |
| OP - PC/PEI | PEI+PC | Oxford Polymers |
| OP - PEI | PEI | Oxford Polymers |
| OP - PPO | PPE+PS | Oxford Polymers |
| OP - PPS | PPS | Oxford Polymers |
| OP - PSU | PSU | Oxford Polymers |
| OPNYL | Nylon 6, Nylon 66 | Ovation Polymers Inc. |
| Oppalyte™ | OPP Film | ExxonMobil Chemical |
| OPTAMID® | Nylon 6 | Schwartz Technical Plastic |
| Optema™ | EMA | ExxonMobil Chemical |
| OpteSTAT™ | PC, PEEK, PES, PETG, PP, Unspecified, PPS, TPU, Unspecified | Ovation Polymers Inc. |
| Opticarb | ABS+PC, PC | The Materials Group |
| OPTICITE™ | PE, Unspecified, Polyolefin, Unspecified, PS (GPPS), PS (HIPS), PS (Specialty) | Dow Plastics |
| Optigard | TS, Unspecified | Dow Corning Corporation |
| Optimum® | Copolyester | RAUH Polymers, Inc. |
| Optital | Acetal (POM) Copolymer | The Materials Group |
| Optix® | Acrylic (PMMA) | Plaskolite West, Inc. |
| OPTODYNE™ | Acrylic, Unspecified, Epoxy | DAIKIN AMERICA, INC. |
| OPTRENE | PP, Unspecified | Ovation Polymers Inc. |
| OPTUM® | Polyolefin, Unspecified | Ferro Corporation |
| Orevac® | EMA, EPE, EVA, HDPE, LLDPE, PE, Unspecified, PP Copolymer, PP Homopolymer, PP, Unspecified | Arkema |
| Orgalloy® | Nylon 6, Nylon 6 Alloy, Nylon 66 Alloy | Arkema |
| ORIENTENE | PP Homopolymer | Oriental Petrochemical Company |
| ORTHTEK® | PEEK | Greene, Tweed & Co. |
| Osterlene® | HDPE, LDPE, LLDPE, MDPE, PP Copolymer, PP Homopolymer, PP Impact Copolymer, PP Random Copolymer, PS (GPPS), PS (HIPS), PS (MIPS) | Osterman & Company |
| O'Tech OE | PVC, Unspecified | O'Tech Corporation |
| O'Tech OF | PVC, Unspecified | O'Tech Corporation |
| O'Tech OM | PVC, Unspecified | O'Tech Corporation |
| O'Tech OW | PVC, Unspecified | O'Tech Corporation |
| Owispol® | PS (GPPS), PS (HIPS) | Firma Chemiczna Dwory S.A. |
| OXNILON 6 | Nylon 6 | Oxford Polymers |
| OXNILON 66 | Nylon 66 | Oxford Polymers |
| OXPEKK® | PEKK | Oxford Performance Materials, Inc. |
| Oxy | PVC, Unspecified | Occidental Chemical Corp. (OxyChem) |
| OxyShield® | Nylon 6 | Honeywell |
| OxyShield® Plus | Nylon 6 | Honeywell |
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