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177.1640 Polystyrene and rubber-modified polystyrene.

Home > Regulations > Indirect food additives: Polymers > 177.1640 Polystyrene and rubber-modified polystyrene.



[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR177.1640]

[Page 313-314]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED)
 
PART 177_INDIRECT FOOD ADDITIVES: POLYMERS--Table of Contents
 
Subpart B_Substances for Use as Basic Components of Single and Repeated 
                        Use Food Contact Surfaces
 
Sec.  177.1640  Polystyrene and rubber-modified polystyrene.

    Polystyrene and rubber-modified polystyrene identified in this 
section may be safely used as components of articles intended for use in 
contact with food, subject to the provisions of this section.
    (a) Identity. For the purposes of this section, polystyrene and 
rubber-modified polystyrene are basic polymers manufactured as described 
in this paragraph so as to meet the specifications prescribed in 
paragraph (c) of this section when tested by the method described in 
paragraph (d) of this section.
    (1) Polystyrene consists of basic polymers produced by the 
polymerization of styrene.
    (2) Rubber-modified polystyrene consists of basic polymers produced 
by combining styrene-butadiene copolymers and/or polybutadiene with 
polystyrene, either during or after polymerization of the polystyrene, 
such that the finished basic polymers contain not less than 75 weight 
percent of total polymer units derived from styrene monomer.
    (b) Optional adjuvants. The basic polymers identified in paragraph 
(a) of this section may contain optional adjuvant substances required in 
the production of such basic polymers. Such optional adjuvant substances 
may include substances permitted for such use by regulations in parts 
170 through 189 of this chapter, substances generally recognized as safe 
in food, and substances used in accordance with a prior sanction or 
approval.
    (c) Specifications. (1) Polystyrene basic polymers identified in 
paragraph (a)(1) of this section shall contain not more than 1 weight 
percent of total residual styrene monomer, as determined by the method 
described in paragraph (d) of this section, except that when used in 
contact with fatty foods of Types III, IV-A, V, VII-A, and IX described 
in table 1 of Sec.  176.170(c) of this chapter, such polystyrene basic 
polymers shall contain not more than 0.5 weight percent of total 
residual styrene monomer.
    (2) Rubber-modified polystyrene basic polymers identified in 
paragraph (a)(2) of this section shall contain not more than 0.5 weight 
percent of total residual styrene monomer, as determined by the method 
described in paragraph (d) of this section.
    (d) Analytical method for determination of total residual styrene 
monomer content--(1) Scope. This method is suitable for the 
determination of residual styrene monomer in all types of styrene 
polymers.
    (2) Principle. The sample is dissolved in methylene chloride. An 
aliquot of the solution is injected into a gas chromatograph. The amount 
of styrene monomer present is determined from the area of the resulting 
peak.
    (3) Apparatus--(i) Gas chromatograph. Beckman GC-2A gas 
chromatograph with hydrogen flame detector or apparatus of equivalent 
sensitivity.
    (ii) Chromatograph column. One-quarter inch outside diameter 
stainless steel tubing (0.028 inch wall thickness), 4 feet in length, 
packed with 20 percent polyethylene glycol (20,000 molecular weight) on 
alkaline treated 60-80 mesh firebrick.

[[Page 314]]

    (iii) Recorder. Millivolt range of 0-1, chart speed of 30 inches per 
hour.
    (4) Reagents. Compressed air, purified; helium gas; hydrogen gas; 
methylene chloride, redistilled; and styrene monomer, redistilled.
    (5) Operating conditions for the gas chromatograph. (i) The column 
is operated at a temperature of 100 [deg]C with a helium flow rate of 82 
milliliters per minute.
    (ii) The hydrogen burner is operated with 15 pounds per square inch 
of air pressure and 7 pounds per square inch of hydrogen pressure.
    (iii) The attenuation of the hydrogen flame detector is set at 
2x10\2\.
    (6) Standardization. (i) Prepare a standard solution by weighing 
accurately 15 to 20 milligrams of styrene monomer into a 2-ounce bottle 
containing 25.0 milliliters of methylene chloride. Cap the bottle 
tightly and shake to thoroughly mix the solution.
    (ii) By means of a microliter syringe, inject 1 microliter of the 
standard solution into the gas chromatograph. Measure the area of the 
styrene monomer peak which emerges after approximately 12 minutes.
    (7) Procedure. (i) Transfer 1 gram of sample (accurately weighed to 
the nearest 0.001 gram to a 2-ounce bottle and add several glass beads. 
Pipette 25.0 milliliters of methylene chloride into the bottle. Cap the 
bottle tightly and place on a mechanical shaker. Shake until the polymer 
is completely dissolved. If any insoluble residue remains, allow the 
bottle to stand (or centrifuge at a low speed) until a clear supernatant 
layer appears.
    (ii) By means of a microliter syringe, inject 3 microliters of the 
clear supernatant liquid into the gas chromatograph.
    (iii) Measure the area of the resulting styrene monomer peak. 
Compare the sample peak area with the area produced by the standard 
styrene monomer solution. Calculation:

Percent residual styrene monomer=Milligrams monomer in standardxpeak 
area of sample/Peak area of monomer standardxsample weight in gramsx30

    (e) Other specifications and limitations. The polystyrene and 
rubber-modified polystyrene identified in and complying with this 
section, when used as components of the food-contact surface of any 
article that is the subject of a regulation in parts 174, 175, 176, 177, 
178 and Sec.  179.45 of this chapter, shall comply with any 
specifications and limitations prescribed by such regulation for the 
article in the finished form in which it is to contact food.
    (f) Nonapplicability. The provisions of this section are not 
applicable to polystyrene and rubber-modified polystyrene used in food-
packaging adhesives complying with Sec.  175.105 of this chapter.





Additives that reference this regulation:


Source: U.S. Code of Federal Regulations - CFR Title 21, Part 177, Section 1640


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