<PAGE>   1

                                                                  EXHIBIT 10.15B

                                    GUARANTY


                  THIS GUARANTY (as amended, supplemented, amended and restated
or otherwise modified from time to time, this "GUARANTY") dated as of October
30, 1997 made by THE GEON COMPANY, a Delaware corporation (the "GUARANTOR"), in
favour of Canadian Imperial Bank of Commerce (the "LENDER").

                              W I T N E S S E T H :

                  WHEREAS pursuant to a Letter Agreement dated as of the date
hereof (as amended, supplemented, amended and restated or otherwise modified
from time to time, the "LETTER AGREEMENT"), between the Borrower (as defined
below) and the Lender, the Lender has extended a $15,000,000 demand operating
facility (the "Facility") in favour of the Borrower;

                  AND WHEREAS pursuant to the terms of the Letter Agreement, the
Guarantor is required to execute and deliver this Guaranty;

                  AND WHEREAS the Guarantor has duly authorized the execution,
delivery and performance of this Guaranty;

                  AND WHEREAS it is in the best interests of the Guarantor to
execute this Guaranty inasmuch as the Guarantor, as the beneficial owner of all
of the issued and outstanding capital stock of the Borrower, will derive
substantial direct and indirect benefits from the extension of credit pursuant
to the Facility made from time to time to the Borrower by the Lender pursuant to
the Letter Agreement;

                  AND WHEREAS the Lender and the Borrower have entered into an
agreement dated as of October 27, 1997, pursuant to which the Lender provided
the Borrower with a bridge credit in the maximum principal amount of
$135,000,000 (the "Credit Agreement");

                  NOW THEREFORE, for good and valuable consideration, the
receipt of which is hereby acknowledged, and in order to induce the Lender to
establish the Facility pursuant to the Letter Agreement, the Guarantor agrees,
for the benefit of the Lender, as follows:


                                    ARTICLE I

                                   DEFINITIONS

         SECTION 1.1 CERTAIN TERMS. The following terms (whether or not
underscored) when used in this Guaranty, including its preamble and recitals,
shall have the following meanings (such definitions to be equally applicable to
the singular and plural forms thereof):


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                                     -2-

         "ACCRUED LIABILITIES" means, at any time, all Obligations which are (or
         but for demand by the Lender (which the Lender is precluded from doing
         by operation of law or court order) would be) due and payable by the
         Borrower to the Lender at the time in accordance with the terms and
         conditions of the Letter Agreement.

         "AGREED CURRENCY" is defined in Section 2.10.

         "BORROWER", means 1250828 Ontario Inc., a corporation existing under
         the laws of the Province of Ontario, and its successors by amalgamation
         or otherwise.

         "CONTINGENT LIABILITIES" means all Obligations, other than the
          Accrued Liabilities.

         "CREDIT AGREEMENT" is defined in the FIFTH RECITAL.

         "FACILITY" is defined in the FIRST RECITAL.

         "GUARANTOR" is defined in the PREAMBLE.

         "GUARANTY" is defined in the PREAMBLE.

         "INTERCORPORATE INDEBTEDNESS" is defined in Section 2.8.

         "JUDGMENT CURRENCY" is defined in Section 2.10.

         "LENDER" is defined in the preamble and includes its successors and
         assigns permitted under the Letter Agreement.

         "LETTER AGREEMENT" is defined in the FIRST RECITAL.

         "OBLIGATIONS" means all indebtedness, liabilities and obligations of
         the Borrower to the Lender arising under the Letter Agreement, whether
         present or future, direct or indirect, absolute or contingent, matured
         or not, at any time owing or remaining unpaid by the Borrower to the
         Lender in any currency, including all principal, interest, commissions,
         fees, reasonable fees and expenses, reasonable legal fees and other
         out-of-pocket costs, indemnities, charges and expenses payable
         thereunder.

         "OTHER CURRENCY" is defined in Section 2.10.

         "RATE OF EXCHANGE" is defined in Section 2.10.

         "U.S. CREDIT AGREEMENT" means that certain credit agreement dated as of
         August 16, 1994, among the Guarantor, Citibank, N.A. as administrative
         agent, Nationsbank of North Carolina, N.A. as co-agent and the other
         institutions noted therein. For greater certainty,



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         the term "U.S. Credit Agreement" as used herein shall include any
         amendments, modifications, supplements, waivers or restatements to such
         agreement only until such date as CIBC Inc. remains a lender to the
         Guarantor pursuant to such agreement.

                  SECTION 1.2. CREDIT AGREEMENT DEFINITIONS. Unless otherwise
defined herein (and except for Article III hereof) or should the context
otherwise require, terms used in this Guaranty, including its preamble and
recitals, have the meanings provided in the Credit Agreement.


                                   ARTICLE II

                               GUARANTY PROVISIONS

         SECTION 2.1. GUARANTY. The Guarantor hereby absolutely, unconditionally
and irrevocably:

         (a) guarantees the full and punctual payment when due in accordance
         with the terms of the Letter Agreement, whether at stated maturity, by
         required prepayment, declaration, acceleration, demand or otherwise, of
         all Obligations whether for principal, interest, fees, expenses or
         otherwise; and

         (b) indemnifies and holds harmless the Lender for any and all
         reasonable out-of-pocket costs and expenses (including reasonable
         attorney's fees and expenses) incurred by the Lender in enforcing any
         rights under this Guaranty after the occurrence of a demand for payment
         of all Accrued Liabilities is made hereunder;

PROVIDED HOWEVER, that the Guarantor shall be liable under this Guaranty for the
maximum amount of such liability that can be hereby incurred without rendering
this Guaranty, as it relates to the Guarantor, voidable under applicable law
relating to fraudulent conveyance or fraudulent transfer, and not for any
greater amount. This Guaranty constitutes a guaranty of payment when due and not
of collection, and the Guarantor specifically agrees that it shall not be
necessary or required that the Lender exercise any right, assert any claim or
demand or enforce any remedy whatsoever against the Borrower (or any other
Person) before or as a condition to the obligations of the Guarantor hereunder.

         SECTION 2.2. ACCELERATION OF GUARANTY. The Guarantor agrees that in the
event of an actual or deemed entry of an order for relief with respect to the
Guarantor under the United States Bankruptcy Code the Guarantor agrees that it
will pay to the Lender promptly following demand the full amount which would be
payable hereunder by the Guarantor in respect of any Accrued Liabilities as if
all such Accrued Liabilities were then due and payable.

         SECTION 2.3. GUARANTY ABSOLUTE ETC. This Guaranty shall in all respects
be a continuing, absolute, unconditional and irrevocable guaranty of payment,
and shall remain in full force and 


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effect until all Obligations have been paid in full in cash, all obligations of
the Guarantor hereunder shall have been paid in full in cash and the Facility
has been terminated. The Guarantor guarantees that the Obligations will be paid
strictly in accordance with the terms of the Letter Agreement, regardless of any
law, regulation or order now or hereafter in effect in any jurisdiction
affecting any of such terms or the rights of the Lender with respect thereto.
The liability of the Guarantor under this Guaranty shall be absolute,
unconditional and irrevocable irrespective of:

         (a)      any lack of validity, legality or enforceability of the Letter
                  Agreement;

         (b)      the failure of the Lender

                  (i) to assert any claim or demand or to enforce any right or
                  remedy against the Borrower or any other Person under the
                  provisions of the Letter Agreement or otherwise, or

                  (ii) to exercise any right or remedy against any other
                  guarantor of, or collateral securing, any Obligations:

         (c) any change in the time, manner or place of payment of, or in any
         other term of, all or any of the Obligations, or any other extension,
         compromise or renewal of any Obligation;

         (d) any reduction, limitation, impairment or termination of the
         Obligations for any reason, other than payment, including any claim of
         waiver, release, surrender, alteration or compromise, and shall not be
         subject to (and the Guarantor hereby waives any right to or claim of)
         any defense or setoff, counterclaim, recoupment or termination
         whatsoever by reason of the invalidity, illegality, nongenuineness,
         irregularity, compromise or unenforceability of, or any other similar
         event or occurrence affecting the Obligations;

         (e) any amendment to, rescission, waiver, or other modification of, or
         any consent to departure from, any of the terms of the Letter
         Agreement;

         (f) any addition, exchange, release, surrender or non-perfection of any
         collateral, or any amendment to or waiver or release or addition of, or
         consent to departure from, any other guaranty, held by the Lender
         securing any of the Obligations;

         (g) the insolvency of, or voluntary or involuntary bankruptcy,
         assignment for the benefit of creditors, reorganization or other
         similar proceedings affecting the Borrower or any of its assets; and

         (h) any other circumstance (other than payment) which might otherwise
         constitute a defense available to, or a legal or equitable discharge
         of, the Borrower, any surety or any guarantor.


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         SECTION 2.4. REINSTATEMENT ETC. The Guarantor agrees that this Guaranty
shall continue to be effective or be reinstated, as the case may be, if at any
time any payment (in whole or in part) of any of the Obligations is rescinded or
must otherwise be restored by the Lender, upon the insolvency, bankruptcy or
reorganization of the Borrower or otherwise, all as though such payment had not
been made.

         SECTION 2.5. WAIVER, ETC. The Guarantor hereby waives promptness,
diligence, notice of acceptance and any other notice with respect to any of the
Obligations and this Guaranty and any requirement that the Lender protect,
secure, perfect or insure any security interest or lien, or any property subject
thereto, or exhaust any right or take any action against the Borrower or any
other Person or entity or any collateral securing the Obligations.

         SECTION 2.6. POSTPONEMENT OF SUBROGATION, ETC. The Guarantor agrees
that it will not exercise any rights which it may acquire by way of rights of
subrogation, reimbursement, exoneration, or indemnification, or any other right
to participate in any claim or remedy under this Guaranty, by any payment made
hereunder, until the payment in full in cash of all Accrued Liabilities demanded
under Section 2.1; PROVIDED, HOWEVER, that if:

         (a)      the Guarantor has made payment to the Lender of all Accrued
                  Liabilities demanded under Section 2.1, and

         (b)      all such Accrued Liabilities have been paid in full in cash,

the Lender agrees that, at the Guarantor's request, the Lender will promptly
execute and deliver to the Guarantor appropriate documents (without recourse and
without representation or warranty, save that such Accrued Liabilities are due
and owing to the Lender and the Lender has not assigned or encumbered such
Accrued Liabilities) requested by the Guarantor to transfer to the Guarantor the
right to receive payment of the Accrued Liabilities so paid by the Guarantor.

         SECTION 2.7.  SUCCESSORS, TRANSFEREES AND ASSIGNS. This Guaranty shall:

         (a)      be binding upon the Guarantor, and its successors, transferees
                  and assigns; and

         (b)      inure to the benefit of and be enforceable by the Lender.

Without limiting the generality of CLAUSE (B), the Lender may, subject to the
terms of the Letter Agreement, assign or otherwise transfer (in whole or in
part) any or all of the Credit to any other Person or entity, and such other
Person or entity shall thereupon become vested with all rights and benefits in
respect thereof granted to the Lender under this Guaranty.

         SECTION 2.8.  POSTPONEMENT.

         (a) All obligations, liabilities and indebtedness, present and future,
         of the Borrower to



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         the Guarantor of any nature whatsoever and all security therefor (the
         "INTERCORPORATE INDEBTEDNESS") are hereby postponed to the Obligations;
         PROVIDED that, until the Lender shall have demanded the repayment of
         any of the Obligations from the Borrower and notice by the Lender to
         the Guarantor that its liability hereunder has become due and payable,
         the Guarantor (subject to the terms and provisions of this Guaranty)
         shall have the right to receive payments in respect of the
         Intercorporate Indebtedness in accordance with the terms thereof.

         (b) If the liabilities of the Guarantor hereunder become due and
         payable, the Lender shall be entitled to receive payment of the
         liabilities of the Guarantor hereunder then due and payable in full
         before the Guarantor shall be entitled to receive any payment on
         account of the Intercorporate Indebtedness. After notice by the Lender
         to the Guarantor that the liabilities of the Guarantor hereunder have
         become due and payable, and for so long as any such liabilities then
         due and payable shall remain unpaid, the Guarantor shall not purport to
         release or withdraw the Intercorporate Indebtedness.

         SECTION 2.9.  WITHHOLDING TAXES.

The Guarantor hereby agrees that:

         (a) All payments by the Guarantor hereunder shall be made free and
         clear of and without deduction for any present or future income,
         excise, stamp or franchise taxes and other taxes, fees, duties,
         withholdings or other charges of any nature whatsoever imposed by any
         taxing authority, but excluding franchise taxes and taxes imposed on or
         measured by the net income, capital or receipts of the Lender (such
         non-excluded items being called "TAXES"). In the event that any
         withholding or deduction from any payment to be made by the Guarantor
         hereunder is required in respect of any Taxes pursuant to any
         applicable law, rule or regulation, then the Guarantor will:

                  (i) pay directly to the relevant authority the full amount
                  required to be so withheld or deducted;

                  (ii) promptly forward to the Lender an official receipt or
                  other documentation satisfactory to the Lender evidencing such
                  payment to such authority; and

                  (iii) pay to the Lender such additional amount or amounts as
                  is necessary to ensure that the net amount actually received
                  by the Lender will equal the full amount the Lender would have
                  received had no such withholding or deduction been required.

                  Moreover, if any Taxes are directly asserted against the
Lender with respect to any payment received by the Lender hereunder, the Lender
may, after requesting the Guarantor to pay the same, allowing a reasonable time
for the Guarantor to do so and the lapse of such reasonable



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                                      -7-

time without payment, pay such Taxes and the Guarantor will promptly pay such
additional amounts (including any penalties, interest or expenses) as is
necessary in order that the net amount received by the Lender after the payment
of such Taxes (including any Taxes on such additional amount) shall equal the
amount the Lender would have received had such Taxes not been asserted.

         (b) If the Guarantor fails to pay any Taxes when due to the appropriate
         taxing authority or fails to remit to the Lender the required receipts
         or other required documentary evidence, the Guarantor shall indemnify
         the Lender for any incremental Taxes, interest or penalties that may
         become payable by the Lender as a result of any such failure.

         (c) Without prejudice to the survival of any other agreement of the
         Guarantor hereunder, the agreements and obligations of the Guarantor
         contained in this Section 2.9 shall survive the payment in full of the
         Obligations.

         (d) If the Lender receives payment from the Guarantor of any Taxes
         pursuant to this Section 2.9 and the official receipts or other
         documentation related thereto referred to in clause (a)(ii) above, the
         Lender shall apply (provided that the Guarantor pays all costs and
         expenses incurred by the Lender in connection with such application)
         for a refund in respect of such Taxes to the extent it is entitled to
         do so under applicable law and promptly pay such refund when received
         to the Guarantor; provided, however, that the Guarantor agrees to
         return such portion of such refund to the Lender promptly after it
         receives notice from the Lender that the Lender is required to return
         any portion of such refund to the relevant taxing authority. Nothing in
         this clause shall be construed to require the Lender to disclose any of
         its tax returns or other confidential or proprietary information to the
         Guarantor or to conduct its business or to arrange or to alter in any
         respect its tax or financial affairs so that it is entitled to receive
         any refund of any Taxes.

         SECTION 2.10.  JUDGMENT CURRENCY.

                  (a) The Guarantor hereby agrees that payments hereunder on
         account of the Obligations shall be made in the currency agreed to
         (the"AGREED CURRENCY")with respect to each such Obligation and if any
         payment is received in another currency (the "OTHER CURRENCY"), such
         payment shall constitute a discharge of the liability of the Guarantor
         only to the extent of the amount of the Agreed Currency which the
         Lender is able to purchase with the amount of the Other Currency
         received by it on the Banking Day next following such receipt in
         accordance with normal procedures and after deducting any out-of-pocket
         costs of exchange.

                  (b) If, for the purpose of obtaining judgment in any court in
         any jurisdiction, it becomes necessary to convert into a particular
         currency (the "JUDGMENT CURRENCY") any amount due in the Agreed
         Currency, then the conversion shall be made on the basis of the rate of
         exchange prevailing on the Banking Day next preceding the day on which
         judgment is given. For the foregoing purposes "RATE OF EXCHANGE" means
         the rate at which the Lender, 



<PAGE>   8
                                      -8-

         in accordance with its normal banking procedures, is able on the
         relevant date to purchase the Agreed Currency with the Judgment
         Currency after deducting any out-of-pocket costs of exchange.

                  (c) The obligation of the Guarantor in respect of any sum due
         to the Lender hereunder shall, notwithstanding any judgment in a
         currency other than the Agreed Currency, be discharged only to the
         extent that on the Banking Day following receipt by the Lender of any
         sum adjudged to be so due in such other currency, the Lender may, in
         accordance with normal banking procedures, purchase the Agreed Currency
         with such other currency after deducting any out-of-pocket costs of
         exchange. In the event that the Agreed Currency so purchased is less
         than the sum originally due to the Lender in the Agreed Currency, the
         Guarantor, as a separate obligation and notwithstanding any such
         judgment, hereby indemnifies and holds harmless the Lender against such
         loss. In the event that the Agreed Currency so purchased is more than
         the sum originally due, the Lender will refund the excess to the
         Guarantor.


                                   ARTICLE III

                    REPRESENTATIONS, WARRANTIES AND COVENANTS

         SECTION 3.1. REPRESENTATIONS AND WARRANTIES. The Guarantor makes and
gives the following representations and warranties to the Lender, upon each of
which the Lender has relied in entering into the Letter Agreement and in
accepting this Guaranty from the Guarantor. Each term used but not defined in
this Article III shall have the meanings provided in the U.S. Credit Agreement.

         (a) The Guarantor is a corporation duly organized, validly existing and
         in good standing under the laws of the State of Delaware.

         (b) The execution, delivery and performance by the Guarantor of this
         Guaranty and the consummation of the transactions contemplated hereby,
         are within the Guarantor's corporate powers, have been duly authorized
         by all necessary corporate action, and do not contravene (i) the
         Guarantor's charter or by-laws or (ii) any law or any contractual
         restriction binding or affecting the Guarantor.

         (c) No authorization or approval or other action by, and notice to or
         filing with, any governmental authority or regulatory body or any other
         third party is required for the due execution, delivery and performance
         by the Guarantor of this Guaranty.

         (d) This Guaranty constitutes a legal, valid and binding obligation on
         the Guarantor, enforceable against the Guarantor in accordance with its
         terms (except as such enforceability may be limited by applicable
         bankruptcy, insolvency, re-organization or


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                                      -9-

         other similar laws affecting creditors' rights generally and by
         principles of equity).

         (e) The Consolidated balance sheet of the Guarantor and its
         Subsidiaries as at December 31, 1996, and the related Consolidated
         statements of income and cash flows of the Guarantor and its
         Subsidiaries for the fiscal year then ended, accompanied by an opinion
         of Ernst & Young, independent public accountants, and the Consolidated
         balance sheet of the Guarantor and its Subsidiaries as at June 30, 1997
         and the related Consolidated statements of income and cash flows of the
         Guarantor and its Subsidiaries for the six months then ended, duly
         certified by the Chief Financial Officer of the Guarantor, copies of
         which have been furnished to the Lender, fairly present, subject, in
         the case of said balance sheet as of June 30, 1997 and said statements
         of income and cash flows for the six months then ended, to year end
         audit adjustments, the Consolidated financial condition of the
         Guarantor and its Subsidiaries as at such dates and the Consolidated
         results of the operations of the Guarantor and its Subsidiaries for the
         periods ended on such dates, all in accordance with generally accepted
         accounting principles consistently applied. Since December 31, 1996,
         there has been no Material Adverse Change (as defined in the Credit
         Agreement).

         (f) To the best of the Guarantor's knowledge, there is no pending or
         threatened action, suit, investigation, litigation or proceeding,
         including, without limitation any Environmental Action, affecting the
         Guarantor or any of its Subsidiaries before any court, governmental
         agency or arbitrator that (i) could be reasonably likely to have a
         Material Adverse Effect other than the litigation identified in
         Schedule A hereto or (ii) purports to affect the legality, validity or
         enforceability of this Guaranty.

         (g) It is not engaged in the business of extending credit for the
         purpose of purchasing or carrying margin stock (within the meaning of
         Regulation U issued by the Board of Governors of the Federal Reserve
         System).

         (h) No ERISA Event has occurred or is reasonably expected to occur with
         respect to any Plan.

         (i) Neither the Guarantor nor any of its ERISA Affiliates has incurred
         or is reasonably expected to incur any Withdrawal Liability to any
         Multiemployer Plan.

         (j) Neither the Guarantor nor any of its ERISA Affiliates has been
         notified by the sponsor of a Multiemployer Plan that such Multiemployer
         Plan is in reorganization or has been terminated, within the meaning of
         Title IV of ERISA, and no such Multiemployer Plan is reasonably
         expected to be in reorganization or to be terminated, within the
         meaning of Title IV of ERISA.

         (k) Except as set forth in the financial statements referred to in
         Section 3.1(e), the Guarantor and its Subsidiaries have no material
         liability with respect to "expected post


<PAGE>   10
                                      -10-

         retirement benefit obligations" within the meaning of Statement of
         Financial Accounting Standards No. 106.

         (l) The operations and properties of the Guarantor and each of its
         Subsidiaries comply in all material respects with all Environmental
         Laws, all necessary Environmental Permits have been obtained and are in
         effect for the operations and properties of the Guarantor and its
         Subsidiaries, the Guarantor and its Subsidiaries are in compliance in
         all material respects with all such Environmental Permits, and no
         circumstances exist that could be reasonably likely to (i) form the
         basis of an Environmental Action against the Guarantor or any of its
         Subsidiaries or any of their properties that could have a Material
         Adverse Effect or (ii) cause any such property to be subject to any
         restrictions on ownership, occupancy, use or transferability under any
         Environmental Law that could have a Material Adverse Effect.

         (m) None of the properties currently or formerly owned or operated by
         the Guarantor or any of its Subsidiaries is listed or proposed for
         listing on the National Priorities List under the Comprehensive
         Environmental Response, Compensation and Liability Act of 1980 ("NPL")
         or on the Comprehensive Environmental Response, Compensation and
         Liability Information System maintained by the U.S. Environmental
         Protection Agency ("CERCLIS") or any analogous state list of sites
         requiring investigation or cleanup, the listing, or proposed listing of
         which would be reasonably likely to have a Material Adverse Effect,
         except as described in the registration statement, Registration No.
         33-70998, declared effective by the Securities and Exchange Commission
         on November 23, 1993 or, to the best knowledge of the Guarantor, is
         adjacent to any such property.

         (n) Except where noncompliance would not individually or in the
         aggregate have a Material Adverse Effect (i) neither the Guarantor nor
         any of its Subsidiaries has transported or arranged for the
         transportation of any Hazardous Materials to any location that is
         listed or proposed for listing on the NPL or on the CERCLIS or any
         analogous state list, and (ii) all Hazardous Materials generated, used,
         treated, handled or stored at or transported to or from any property
         currently or formerly owned or operated by the Guarantor or any of its
         Subsidiaries have been disposed of in compliance with all Environmental
         Laws and Environmental Permits.


         SECTION 3.2. COVENANTS. The Guarantor will, during the term of this
         Guaranty:

         (a) Comply, and cause each of its Subsidiaries (other than Synergistics
         and, subsequent to the Amalgamation the Borrower (as each such term is
         defined in the Credit Agreement)) to comply, in all material respects,
         with all applicable laws, rules, regulations and orders, such
         compliance to include, without limitation, compliance with ERISA and
         Environmental Laws as provided in Section 3.2(j).

         (b) Pay and discharge, and cause each of its Subsidiaries to pay and
         discharge, before 



<PAGE>   11
                                      -11-

         the same shall become delinquent, (i) all taxes, assessments and
         governmental charges or levies imposed upon it or upon its property and
         (ii) all lawful claims that, if unpaid, might by law become a Lien upon
         its property; provided, however, that neither the Guarantor nor any of
         its Subsidiaries shall be required to pay or discharge any such tax,
         assessment, charge or claim that is being contested in good faith and
         by proper proceedings and as to which appropriate reserves are being
         maintained, unless and until any Lien resulting therefrom attaches to
         its property and becomes enforceable against its other creditors.

         (c) Maintain, and cause each of its Subsidiaries to maintain, insurance
         with responsible and reputable insurance companies or associations in
         such amounts and covering such risks as is usually carried by companies
         engaged in similar business and owning similar properties in the same
         general areas in which the Guarantor or such Subsidiary operates;
         provided, however, that the Guarantor and its Subsidiaries may
         self-insure to the same extent as is consistent with its past practice
         and to the extent consistent with prudent business practice.

         (d) Preserve and maintain, and cause each of its Subsidiaries to
         preserve and maintain, its corporate existence, rights (charter and
         statutory) and franchises; provided, however, that the Guarantor and
         its Subsidiaries may consummate any merger or consolidation permitted
         under Section 5.02(b) of the U.S. Credit Agreement; and provided that
         the Borrower and Synergistics may consummate any Second Step
         Transaction or an Amalgamation (as each such term is defined in the
         Credit Agreement); and provided further that neither the Guarantor nor
         any of its Subsidiaries shall be required to preserve any right or
         franchise if the Board of Directors of the Guarantor or such Subsidiary
         shall determine that the preservation thereof is no longer desirable in
         the conduct of the business of the Guarantor or such Subsidiary, as the
         case may be, and that the loss thereof is not disadvantageous in any
         material respect to the Guarantor, such Subsidiary or the lender under
         the U.S. Credit Agreement.

         (e) At any reasonable time and from time to time, permit the Lender or
         its agents or representatives thereof, to examine and make copies of
         and abstracts from the records and books of account of, and visit the
         properties of, the Guarantor, and to discuss the affairs, finances and
         accounts of the Guarantor and any of its Subsidiaries with any of the
         officers or directors of the Guarantor and with their independent
         certified public accountants.

         (f) Keep, and cause each of its Subsidiaries to keep, proper books of
         record and account, in which full and correct entries shall be made of
         all financial transactions and the assets and business of the Guarantor
         and each such Subsidiary in accordance with generally accepted
         accounting principles in effect from time to time.

         (g) Maintain and preserve, and cause each of its Subsidiaries (other
         than Synergistics and, subsequent to the Amalgamation, the Borrower (as
         each such term is defined in the Credit Agreement)) to maintain and
         preserve, all of its properties that are used or useful in



<PAGE>   12
                                      -12-

         the conduct of its business in good working order and condition,
         ordinary wear and tear excepted.

         (h) Conduct, and cause each of its Subsidiaries to conduct, all
         transactions otherwise permitted under the U.S. Credit Agreement with
         any of their Affiliates on terms that are fair and reasonable and no
         less favourable to the Guarantor or such Subsidiary than it would
         obtain in a comparable arm's-length transaction with a Person not an
         Affiliate.

         (i)      Furnish to the Lender:

                  (i) as soon as available and in any event within 60 days after
                  the end of each of the first three quarters of each fiscal
                  year of the Guarantor, Consolidated balance sheets of the
                  Guarantor and its Subsidiaries as of the end of such quarter
                  and Consolidated statements of income and cash flows of the
                  Guarantor and its Subsidiaries for the period commencing at
                  the end of the previous fiscal year and ending with the end of
                  such quarter, duly certified (subject to year-end audit
                  adjustments) by the chief financial officer or the controller
                  of the Guarantor as having been prepared in accordance with
                  GAAP, it being agreed that delivery of the Guarantor's
                  Quarterly Report on Form 10-Q will satisfy this requirement;

                  (ii) as soon as available and in any event within 120 days
                  after the end of each fiscal year of the Guarantor, a copy of
                  the annual audit report for such year for the Guarantor and
                  its Subsidiaries, containing Consolidated balance sheets of
                  the Guarantor and its Subsidiaries as of the end of such
                  fiscal year and Consolidated statements of income and cash
                  flows of the Guarantor and its Subsidiaries for such fiscal
                  year, in each case accompanied by an opinion acceptable to the
                  Lender by Ernst & Young or other independent public
                  accountants acceptable to the Lender; and

                  (iii) such other information respecting the condition or
                  operations, financial or otherwise, of the Guarantor or any of
                  its Subsidiaries as the Lender may from time to time
                  reasonably request.

         (j) Comply, and cause each of its Subsidiaries and all lessees and
         other Persons operating or occupying it's properties to comply, in all
         material respects, with all applicable Environmental Laws and
         Environmental Permits; obtain and renew and cause each of its
         Subsidiaries to obtain and renew all Environmental Permits necessary
         for its operations and properties; and conduct, and cause each of its
         Subsidiaries to conduct, any investigation, study, sampling and
         testing, and undertake any cleanup, removal, remedial or other action
         necessary to remove and clean up all Hazardous Materials from any of
         its properties pursuant to the order of any regulatory authority and
         generally in accordance with the requirements of all Environmental
         Laws; provided, however, that neither the Guarantor nor any of its
         Subsidiaries shall be required to undertake any such cleanup, removal,
         remedial or

<PAGE>   13
                                      -13-

         other action to the extent that its obligations to do so is being
         contested in good faith and by proper proceedings and appropriate
         reserves are being maintained with respect to such circumstances.


                                   ARTICLE IV

                            MISCELLANEOUS PROVISIONS

         SECTION 4.1.  DOCUMENT.  This Guaranty is executed pursuant to the 
Letter Agreement.

         SECTION 4.2. INFORMATION. The Guarantor assumes all responsibility for
being and keeping itself informed of the Borrower's financial condition and
assets, and of all other circumstances bearing upon the risk of nonpayment of
the Obligations and the nature, scope and extent of the risks that the Guarantor
assumes and incurs hereunder, and agrees that the Lender will have no duty to
advise the Guarantor of information known to it regarding such circumstances or
risks.

         SECTION 4.3. BINDING ON SUCCESSORS, TRANSFERRED ASSIGNS; ASSIGNMENT. In
addition to, and not in limitation of, Section 2.7, this Guaranty shall be
binding upon the Guarantor and its successors, transferees and assigns and shall
inure to the benefit of and be enforceable by the Lender and its successors,
transferees and assigns (to the full extent provided pursuant to Section 2.7);
PROVIDED, HOWEVER, that the Guarantor may not delegate any of its obligations
hereunder without the prior written consent of the Lender, such consent not to
be unreasonably withheld, and any purported assignment in the absence of such
consent shall be void.

         SECTION 4.4. AMENDMENTS, ETC. No amendment to or waiver of any
provision of this Guaranty, nor consent to any departure by the Guarantor
herefrom, shall in any event be effective unless the same shall be in writing
and signed by the Lender and then such waiver or consent shall be effective only
in the specific instance and for the specific purpose for which given.

         SECTION 4.5. ADDRESSES FOR NOTICES TO THE GUARANTOR. Any notice or
communication to be given under this Guaranty to the Guarantor may be
effectively given by delivering the same to either the Guarantor at One Geon
Center, P.O. Box 122, Avon Lake, Ohio 44012, U.S.A., Attention: Jean M.
Miklosko, Treasurer or to the Guarantor c/o Fasken Campbell Godfrey, 4200 -
Toronto Dominion Bank Tower, Box 20, Toronto-Dominion Centre, Toronto, Ontario,
M5K 1N6, Attention: Jon J. Holmstrom, and marked URGENT or by sending the same
by prepaid registered mail to it at such address. Any notice so delivered or
mailed shall be effective when received. Any notice or communication to be given
under this Guaranty to the Lender shall be effective if given in accordance with
the provisions of the Letter Agreement as to the giving of notice to it, and the
Lender may change its address for notices in accordance with the said
provisions.

         SECTION 4.6. NO WAIVER; REMEDIES. In addition to, and not in limitation
of, Sections 2.3



<PAGE>   14
                                     -14-

and 2.5, no failure on the part of the Lender to exercise, and no delay in
exercising, any right hereunder shall operate as a waiver thereof; nor shall any
single or partial exercise of any right hereunder preclude any other or further
exercise thereof or the exercise of any other right. No waiver of any of such
rights and no modification, amendment or discharge of this Guaranty shall be
deemed to be made by the Lender or shall be effective unless the same shall be
in a writing executed and delivered by the Lender and then such waiver shall
apply only with respect to the specific instance involved and shall in no way
impair the rights of the Lender or the obligations of the Guarantor to the
Lender in any other respect at any other time. The remedies herein provided are
cumulative and not exclusive of any remedies provided by law.

         SECTION 4.7. CAPTIONS. Captions used in this Guaranty are for
convenience of reference only, and shall not affect the construction of this
Guaranty.

         SECTION 4.8. SETOFF. In addition to, and not in limitation of, any
rights of the Lender under applicable law, the Lender shall, after demand of all
Accrued Liabilities is made hereunder, have the right to appropriate and apply
to the payment of the obligations of the Guarantor owing to it hereunder,
whether or not then due any and all balances, credits, deposits, accounts or
moneys of the Guarantor then or thereafter maintained with the Lender, or any
agent or bailee for the Lender. The Lender agrees to promptly notify the
Guarantor after any such setoff and application, provided that the failure to
give such notice shall not affect the validity of such setoff and application.

         SECTION 4.9. SEVERABILITY. Wherever possible each provision of this
Guaranty shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Guaranty shall be prohibited by or
invalid under such law, such provision shall be ineffective to the extent of
such prohibition or invalidity, without invalidating the remainder of such
provision or the remaining provisions of this Guaranty.

         SECTION 4.10. WAIVERS. The Guarantor hereby waives notice of acceptance
of this Guaranty, notice of the creation, renewal or accrual of any of the
Obligations and notice or proof of reliance by the Lender upon this Guaranty,
and waives diligence, protest, notice of protest, presentment, demand of
payment, notice of dishonor or nonpayment of any of the Obligations, suit or
taking other action or making any demand against, and any other notice to the
Borrower or any other party liable thereon.

         SECTION 4.11. VARIOUS MATTERS. So far as the Guarantor is concerned,
the Lender may, at any time and from time to time, without the consent of, or
notice to the Guarantor, and without impairing or releasing any of the
obligations of the Guarantor hereunder, upon or without any terms or conditions
and in whole or in part:

                  (a) modify or change the manner, place or terms of, and/or
         change or extend the time of payment of, renew or alter, any of the
         Obligations, any security therefor, or any liability incurred directly
         or indirectly in respect thereof, provided that such modification,
         change, extension, renewal or alteration, or the manner in which it was
         implemented, does 



<PAGE>   15
                                      -15-

         not violate the provision of the Letter Agreement, and this Guaranty
         shall apply to the Obligations as so modified, changed, extended,
         renewed or altered;

                  (b) sell, exchange, release, surrender, realize upon or
         otherwise deal with, in any manner and in any order, any property by
         whomsoever at any time pledged or mortgaged to secure, or howsoever
         securing the Obligations or any liabilities (including any of those
         hereunder) incurred directly or indirectly in respect thereof or
         hereof, and/or any offset or right with respect thereto;

                  (c) exercise or refrain from exercising any rights against the
         Borrower or others;

                  (d) settle or compromise any of the Obligations, any security
         therefor or any liability (including any of those hereunder) incurred
         directly or indirectly in respect thereof or hereof, and subordinate
         the payment of all or any part thereof to the payment of any liability
         (whether due or not) of the Borrower to creditors of the Borrower other
         than the Lender;

                  (e) apply any sums paid by or howsoever realized from any
         Person (other than the Borrower or Guarantor) to any of the Obligations
         regardless of what liability or liabilities of the Borrower remain
         unpaid; provided however that any sums paid to the Lender by reason of
         the Obligations shall be applied to satisfy the Obligations to the
         extent paid; and

                  (f) amend or otherwise modify the Letter Agreement, consent to
         or waive any breach of, or any act, omission or default under the
         Letter Agreement, or any agreements, instruments or documents referred
         to therein or executed and delivered pursuant thereto or in connection
         therewith, and this Guaranty shall apply to the Obligations as set
         forth in each of such documents as so amended and modified. Any such
         action, shall not impair or release any of the obligations of the
         Guarantor hereunder.

         SECTION 4.12. SURVIVAL. Notwithstanding any other provision of this
Guaranty, the liabilities of the Guarantor under this Guaranty in respect of the
Contingent Liabilities shall survive for a period of five years from the date
all principal and interest, fees and other Accrued Liabilities have been paid to
the Lender, whether pursuant to the Letter Agreement, this Guaranty or
otherwise.

         SECTION 4.13. KNOWLEDGE. All provisions contained herein requiring the
Guarantor to make a determination or assessment of any event or circumstance or
other matter to the best of its knowledge shall be construed to represent the
actual knowledge of the President and Chief Executive Officer, Senior Vice
President Technology/Engineering, Senior Vice President Commercial, Vice
President Operations, Vice President General Counsel and Secretary and Chief
Financial Officer and Senior Vice President, Human Resources of the Guarantor,
after such individuals have made all inquiries and investigations as may be
reasonably necessary in the 



<PAGE>   16
                                      -16-

circumstances before making any such determination or assessment.

         SECTION 4.14. GOVERNING LAW. This Guaranty shall be governed by, and
construed in accordance with, the laws of the State of New York.

         SECTION 4.15.  JURISDICTION, ETC.

                  (a) The Guarantor hereby irrevocably and unconditionally
         submits, for itself and its property, to the non-exclusive jurisdiction
         of any New York State court or Federal court of the United States of
         America sitting in New York City, and any appellate court from any
         thereof, in any action or proceeding arising out of or relating to this
         Guaranty, or for recognition or enforcement of any judgment, and the
         Guarantor hereby irrevocably and unconditionally agrees that all claims
         in respect of any such action or proceeding may be heard and determined
         in any such New York State court or, to the extent permitted by law, in
         such Federal court. The Guarantor agrees that a final judgment in any
         such action or proceeding shall be conclusive and may be enforced in
         other jurisdictions by suit on the judgment or in any other manner
         provided by law. Nothing in this Guaranty shall affect any right that
         the Lender may otherwise have to bring any action or proceeding
         relating to this Guaranty in the courts of any jurisdiction.

                  (b) The Guarantor hereby irrevocably and unconditionally
         waives, to the fullest extent it may legally and effectively do so, any
         objection that it may now or hereafter have to the laying of venue of
         any suit, action or proceeding arising out of or relating to this
         Guaranty in any New York State or Federal court. The Guarantor hereby
         irrevocably waives, to the fullest extent permitted by law, the defense
         of an inconvenient forum to the maintenance of such action or
         proceeding in any such court.

         SECTION 4.16. WAIVER OF JURY TRIAL. The Guarantor hereby irrevocably
waives all right to trial by jury in any action, proceeding or counter-claim
(whether based on contract, tort or otherwise) arising out of or relating to
this Guaranty or the actions of the Lender in the negotiation, administration or
enforcement thereof.

         IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be duly
executed and delivered by its officer thereunto duly authorized as of the date
first above written.


                                            THE GEON COMPANY



                                            By: /s/ Jean M. Miklosko
                                               -------------------------------
                                                     Name:  Jean M. Miklosko
                                                     Title: Treasurer