| EXHIBIT      10.5.7                                        |
|------------------------------------------------------------|
|  Seventh      Amendment to the                        |
|  Amended      and Restated Revolving Credit Agreement |
|                                                       |

| 1. | Amendment to Section      1.1. The Parties agree to amend Section 1.1 of the Credit      Agreement by Replacing the definition of “Scheduled Termination Date” with      the following definition: |
|----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2. | No Other Amendment or      Waiver. Except as expressly amended by this Amendment, the Credit      Agreement and all other Loan Documents remain in full force and effect in      accordance with their terms, and the Parties ratify and confirm the Credit      Agreement and all other Loan Documents in all  respects. |
|----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 3. | Execution in      Counterparts. This amendment may be executed in any number of      counterparts and and by different parties in separate counterparts, each      of which when so executed will be deemed to be an original and all of      which taken together will constitute one and the same agreement. Signature      pages may be detached from multiple separate counterparts and attached to      a single counterpart so that all signature pages are attached to the same      document. |
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| 4. | Governing Law.      This Amendment and the rights and obligation of the Parties to this      Amendment will be governed by, and construed and interpreted in accordance      with, the law of the State of NewYork. |
|----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 5. | Subsidiary      Guarantors. The Guarantors to this Agreement will only be bound by      their guarantees if they remain a wholly owned subsidiary of the      Borrower. |
|----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| LENDER:                       | SUBSIDIARY      GUARANTORS:              |
|-------------------------------|------------------------------------------|
|                          |                                     |
| THE      DOW CHEMICAL COMPANY | K-DOW      PETROCHEMICALS UC SUB C, INC. |

| By:    | /s/      FERNANDO RUIZ                                          |   | By:    | /s/      MICHAEL L. GLENN                           |
|--------|-----------------------------------------------------------------|--------|--------|-----------------------------------------------------|
| Name:  |      Fernando      Ruiz                |   | Name:  |      Michael      L. Glenn |
| Title: |      Corporate      Vice President and |   | Title: |      Secretary             |
|   |      Treasurer                         |   |   |                                                |

| BORROWER:                          |                                                           |
|------------------------------------|----------------------------------------------------------------|
|                               |                                                           |
|  UNION      CARBIDE CORPORATE | UNION      CARBIDE CHEMICALS &PLASTICS      TECHNOLOGY LLC |

| By:    | /s/      EUDIO GIL                                               |   | By:    | /s/      MARK A WHITEMAN                            |
|--------|------------------------------------------------------------------|--------|--------|-----------------------------------------------------|
| Name:  |      Eudio      Gil                     |   | Name:  |      Mark      A. Whiteman |
| Title: |      Chief      Financial Officer, Vice |   | Title: |      Vice      President   |
|   |      President,      and Treasurer      |   |   |                                                |

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