JOINDER AGREEMENT

THIS JOINDER AGREEMENT, dated as of June 7, 2006 (this “Agreement”), by and
among AMEGY BANK NATIONAL ASSOCIATION (the “Lender”), KRATON POLYMERS LLC, a
Delaware limited liability corporation, as the borrower (“Company”), each of the
Guarantors listed on the signature pages hereto (the “Guarantors”), and UBS AG,
STAMFORD BRANCH, as Administrative Agent.

RECITALS:

WHEREAS, reference is hereby made to the CREDIT AND GUARANTY AGREEMENT, dated as
of December 23, 2003 (as amended pursuant to that certain Amendment No. 1 to
Credit and Guaranty Agreement dated as of March 4, 2004, that certain Amendment
No. 2 to Credit and Guaranty Agreement dated as of October 21, 2004, that
certain Amendment No. 3 to Credit and Guaranty Agreement dated as of
February 16, 2006, and that certain Amendment No. 4 to Credit and Guaranty
Agreement dated as of May 12, 2006, and as further amended, restated
supplemented or otherwise modified from time to time, the “Credit Agreement’’;
the terms defined therein and not otherwise defined herein being used herein as
therein defined), by and among the Company, the Guarantors, the Lenders party
thereto from time to time, Goldman Sachs Credit Partners L.P. and UBS Securities
LLC, as Lead Arrangers, and UBS AG, Stamford Branch, as Administrative Agent and
Collateral Agent;

WHEREAS, reference is hereby made to Amendment No. 4 to Credit and Guaranty
Agreement dated as of May 12, 2006 (“Amendment No. 4”) among the Company, the
Guarantors, the Lenders party thereto and the Administrative Agent.

WHEREAS, subject to the terms and conditions of Amendment No. 4, Company may
increase the existing Revolving Commitments by an amount up to $20,000,000 by
entering into one or more Joinder Agreements with Eligible Assignees.

NOW, THEREFORE, in consideration of the premises and agreements, provisions and
covenants herein contained, the parties hereto agree as follows:

The Lender hereby agrees to commit to provide its respective Commitment as set
forth on Schedule A annexed hereto, on the terms and subject to the conditions
set forth below:

The Lender (i) confirms that it has received a copy of the Credit Agreement and
the other Credit Documents, together with copies of the financial statements
referred to therein and such other documents and information as it has deemed
appropriate to make its own credit analysis and decision to enter into this
Joinder Agreement (this “Agreement”); (ii) agrees that it will, independently
and without reliance upon the Administrative Agent or any other Lender or Agent
and based on such documents and information as it shall deem appropriate at the
time, continue to make its own credit decisions in taking or not taking action
under the Credit Agreement; (iii) appoints and authorizes Administrative Agent
and Syndication Agent to take such action as agent on its behalf and to exercise
such powers under the Credit Agreement and the other Credit Documents as are
delegated to Administrative Agent and Syndication Agent, as the case may be, by
the terms thereof, together with such powers as are reasonably incidental
thereto; and (iv) agrees that it will perform in accordance with their terms all
of the obligations which by the terms of the Credit Agreement are required to be
performed by it as a Lender.

Each Lender hereby agrees to make its Commitment on the following terms and
conditions:

1.   Increase in Revolving Commitments. This Agreement represents Company’s
request to increase the amount of Revolving Commitments (the “New Revolving Loan
Commitments”) by an amount equal to that set forth opposite the name of the
Lender on Schedule A hereto as of the date hereof (the “Increased Amount Date”).

2.   Assignments and Purchases. The Lender hereby agrees, to the extent deemed
necessary by, and in such manner as is satisfactory to, the Administrative
Agent, (a) to purchase from each Lender holding Revolving Commitments, at the
principal amount thereof (together with accrued interest), interests in the
Revolving Loans outstanding on the Increased Amount Date and (b) to assign to
each other lender with New Revolving Loan Commitments from time to time after
the Increased Amount Date, in each case as shall be necessary in order that,
after giving effect to all such assignments and purchases, the Revolving Loans
will be held by existing Revolving Loan Lenders and lenders with New Revolving
Loan Commitments ratably in accordance with their Revolving Commitments after
giving effect to the addition of such New Revolving Loan Commitments to the
Revolving Commitments.

3.   New Lenders. If the Lender is not already a party to the Credit Agreement,
it acknowledges and agrees that upon its execution of this Agreement, it shall
become a “Lender” under, and for all purposes of, the Credit Agreement and the
other Credit Documents, and shall be subject to and bound by the terms thereof,
and shall perform all the obligations of and shall have all rights of a Lender
thereunder.

4.   Credit Agreement Governs. New Revolving Loan Commitments and any borrowings
made thereunder (“New Revolving Loans”) shall otherwise be subject to the
provisions of the Credit Agreement and the other Credit Documents.

5.   Eligible Assignee. By its execution of this Agreement, the Lender
represents and warrants that it is an Eligible Assignee.

6.   Notice. For purposes of the Credit Agreement, the initial notice address of
the Lender shall be as set forth below its signature below.

7.   Non-US Lenders. If the Lender is a Non-US Lender, delivered herewith to
Administrative Agent are such forms, certificates or other evidence with respect
to United States federal income tax withholding matters as the Lender may be
required to deliver to Administrative Agent pursuant to subsection 2.20(c) of
the Credit Agreement.

8.   Amendment, Modification and Waiver. This Agreement may not be amended,
modified or waived except by an instrument or instruments in writing signed and
delivered on behalf of each of the parties hereto.

9.   Entire Agreement. This Agreement, the Credit Agreement and the other Credit
Documents constitute the entire agreement among the parties with respect to the
subject matter hereof and thereof and supersede all other prior agreements and
understandings, both written and verbal, among the parties or any of them with
respect to the subject matter hereof.

10.   GOVERNING LAW. THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE
PARTIES HEREUNDER SHALL BE GOVERNED BY, AND SHALL BE CONSTRUED AND ENFORCED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

11.   Severability. Any term or provision of this Agreement which is invalid or
unenforceable in any jurisdiction shall, as to that jurisdiction, be ineffective
to the extent of such invalidity or unenforceability without rendering invalid
or unenforceable the remaining terms and provisions of this Agreement or
affecting the validity or enforceability of any of the terms or provisions of
this Agreement in any other jurisdiction. If any provision of this Agreement is
so broad as to be unenforceable, the provision shall be interpreted to be only
so broad as would be enforceable.

12.   Counterparts. This Agreement may be executed in counterparts, each of
which shall be deemed to be an original, but all of which shall constitute one
and the same agreement.

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IN WITNESS WHEREOF, each of the undersigned has caused its duly authorized
officer to execute and deliver this Joinder Agreement as of the date first
referenced above.

AMEGY BANK NATIONAL ASSOCIATION

By: /s/ Laif Afseth
Name: Laif Afseth
Title: Senior Vice President

Notice Address:
1801 Main Street
TH-A007-5765
Houston, Texas 77002

Attention: Maxine Hunter, Faye Cain
Telephone: 713-232-6355, 713-232-6363
Facsimile: 713-693-7467

KRATON POLYMERS LLC

By: /s/ Raymond K. Guba
Name: Raymond K. Guba
Title: Vice President and Chief Financial Officer

GUARANTORS:

POLYMER HOLDINGS LLC

ELASTOMERS HOLDINGS LLC
KRATON POLYMERS U.S. LLC
KRATON POLYMERS CAPITAL CORPORATION

By: /s/ Raymond K. Guba
Name: Raymond K. Guba
Title: Vice President and Chief Financial Officer

Consented to by:

UBS AG, STAMFORD BRANCH
as Administrative Agent

By: /s/ Richard L. Tavrow
Name: Richard L. Tavrow
Title: Director Banking Product Services, US

By: /s/ Vladimira Holeckova
Name: Vladimira Holeckova
Title: Associate Director Banking Product Services, US

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SCHEDULE A
TO JOINDER AGREEMENT

                  Name of Lender   Type of Commitment   Amount
AMEGY BANK NATIONAL ASSOCIATION
  New Revolving Loan Commitment
  $ 15,000,000  
 
               

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