Method for altering polymer properties for molding of parts

Patent metadata

Field	Value
Publication number	US-11401394-B2
Application number	US-202017014679-A
Country	US
Kind code	B2
Filing date	Sep 8, 2020
Priority date	Sep 6, 2019
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

A method for altering polymer properties for the molding of parts comprises exposing, to a scission-causing stressor, a region of a polymer form. The scission-causing stressor is controlled to achieve, in a relatively higher molecular-weight polymer at the region, an amount of scission that results in a reduction in the molecular weight of the relatively higher molecular-weight polymer, thereby forming a relatively lower molecular-weight polymer at the region.

First claim

What is claimed:

1. A method comprising:
exposing, to a first scission-causing stressor, a first region of a first polymer form, the first polymer form including fibers, wherein:
(a) a first parameter of the first scission-causing stressor is controlled to achieve a first amount of scission in a first relatively higher molecular-weight polymer at the first region,
(b) the first amount of scission resulting in a reduction in a weight average molecular weight of the first relatively higher molecular-weight polymer, thereby forming a first relatively lower molecular-weight polymer at the first region,
(c) the reduction is in a range of about 10 to about 50 percent, and
(d) the weight average molecular weight of the first relatively higher molecular-weight polymer at a second region of the first polymer form is not reduced; and

creating a desired surface finish of the first polymer form, or a part formed therefrom, by applying pressure to the first polymer form, the pressure causing the first relatively lower molecular-weight polymer to flow to a surface of the first polymer form, wherein the desired surface finish is characterized by a lack of a visible or physical presence of the fibers.

2. The method of claim 1 wherein the scission-causing stressor is selected from the group consisting of ultraviolet light, temperature, a chemical, and ultrasound.

3. The method of claim 1 wherein applying pressure comprises placing the first polymer form in a mold cavity and applying pressure to the mold cavity.

4. A method comprising:
exposing, to a first scission-causing stressor, a first region of a first polymer form, the first polymer form including fibers, wherein:
(a) a first parameter of the first scission-causing stressor is controlled to achieve a first amount of scission in a first relatively higher molecular-weight polymer at the first region,
(b) the first amount of scission resulting in a reduction in a weight average molecular weight of the first relatively higher molecular-weight polymer, thereby forming a first relatively lower molecular-weight polymer at the first region,
(c) the reduction is in a range of about 10 to about 50 percent, and
(d) the weight average molecular weight of the first relatively higher molecular-weight polymer at a second region of the first polymer form is not reduced; and

within a mold cavity, flowing the first relatively lower molecular-weight polymer into a first cavity for forming a fine feature, and completely filling the first cavity with the relatively lower molecular-weight polymer by applying pressure to the mold cavity.

5. A method comprising:
exposing, to a first scission-causing stressor, a first region of a first fiber-bundle-based preform, the first fiber-bundle-based preform including plural aligned fibers and resin,
exposing, to a second scission-causing stressor, a first region of a second fiber-bundle-based preform, the second fiber-bundle-based preform including plural aligned fibers and resin, wherein:
(a) a first parameter of the first scission-causing stressor is controlled to achieve a first amount of scission in a first relatively higher molecular-weight polymer at the first region of the first fiber-bundle-based preform,
the first amount of scission resulting in a reduction in a weight average molecular weight of the first relatively higher molecular-weight polymer, thereby forming a first relatively lower molecular-weight polymer at the first region of the first polymer form,
(b) a first parameter of the second scission-causing stressor is controlled to achieve a second amount of scission in a second relatively higher molecular-weight polymer at the first region of the second fiber-bundle-based preform, the second amount of scission resulting in a reduction in a weight average molecular weight of the second relatively higher molecular-weight polymer, thereby forming a second relatively lower molecular-weight polymer at the first region of the second fiber-bundle-based preform,
(c) the reduction in the weight average molecular weight of the first relatively higher molecular weight polymer is in a range of about 10 to about 50 percent,
(d) the reduction in the weight average molecular weight of the second relatively higher molecular weight polymer is in a range of about 10 to about 50 percent,
(e) the weight average molecular weight of the first relatively higher molecular-weight polymer at a second region of the first fiber-bundle-based preform, and of the second relatively higher molecular-weight polymer at a second region of the second fiber-bundle-based preform is not reduced; and wherein,

with the first fiber-bundle-based preform and the second fiber-bundle-based preform abutting one another at respective first regions thereof, applying heat to the first fiber-bundle-based preform and the second fiber-bundle based preform, wherein the heat is applied at or above the melt temperature of the first relatively lower molecular-weight polymer and the second relatively lower molecular-weight polymer, and below the melt temperature of the first higher molecular-weight polymer and the second relatively higher molecular weight polymer, thereby bonding the first region of the first fiber-bundle-based preform to the first region of the second fiber-bundle-based preform.

6. The method of claim 5 wherein the heat is uniformly applied to the first fiber-bundle-based preform and the second fiber bundle-based preform.

7. The method of claim 5 wherein the first relatively higher molecular-weight polymer and the second relatively higher molecular-weight polymer are the same polymer.

8. The method of claim 7 wherein first scission-causing stressor and the second scission-causing stressor are the same scission-causing stressor.

9. The method of claim 5 wherein the first relatively higher molecular-weight polymer and the second relatively higher molecular-weight polymer are different relatively higher molecular-weight polymers.

10. The method of claim 9 wherein the first scission-causing stressor and the second scission-causing stressor are the same scission-causing stressor.

11. The method of claim 10 wherein the first parameter of the first scission-causing stressor and the first parameter of the second scission-causing stressor are the same parameter.

12. The method of claim 11 wherein an amount of the reduction in the weight average molecular weight of the first relatively higher molecular-weight polymer and an amount of the reduction in the weight average molecular-weight polymer of the second relatively higher molecular-weight polymer are different amounts.

13. The method of claim 11 wherein a value for the first parameter of the first scission-causing stressor to achieve a first amount of scission in the first relatively higher molecular-weight polymer is different than a value for the first parameter of the second scission-causing stressor to achieve a first amount of scission in the second relatively higher molecular-weight polymer.

Assignees

• Arris Composites Inc

Inventors

• Reese Riley
• Escowitz Ethan

Classifications

• B29C71/04

  by wave energy or particle radiation {, e.g. for curing or vulcanising preformed articles (during moulding, e.g. in a mould B29C35/08)} · CPC title

• B29C66/91935

  lower than said fusion temperature · CPC title

• B29C66/028

  Non-mechanical surface pre-treatments, i.e. by flame treatment, electric discharge treatment, plasma treatment, wave energy or particle radiation (B29C65/14 takes precedence; non-mechanical surface treatment of plastics in general B29C59/08 - B29C59/16) · CPC title

• B29C2035/0827

  using UV radiation · CPC title

• B29C66/721

  Fibre-reinforced materials (B29C66/729 takes precedence) · CPC title